Inventors:

Yufen Hu, Stanislaw Rachwal, and Bogumila Rachwal

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of priority to U.S. Provisional Patent Application No. 61/986,620, filed April 30, 2014, which is fully incorporated herein by reference for all purposes.

BACKGROUND

Field

[0002] Embodiments generally relate to a wavelength conversion film. The wavelength conversion film comprises an optically transparent polymer matrix and fluorescent composite particles, wherein the fluorescent composite particles are individually between about 5 nm and 1 μιη in diameter and are dispersed within the optically transparent polymer matrix, and wherein the fluorescent composite particles comprise an inorganic oxide matrix and a chromophore, wherein the chromophore is embedded into the inorganic oxide matrix, and wherein the chromophore converts incoming photons of a particular wavelength to a different wavelength. In some embodiments the inorganic oxide matrix comprises silica. The wavelength conversion film is useful for several applications including, improving the solar harvesting efficiency of solar energy conversion devices, and greenhouse roofing materials. The wavelength conversion film disclosed herein provides stable optical wavelength converting function for significantly longer time periods than conventional films.

Description of the Related Art

[0003] Wavelength conversion films are often used in optical applications to convert photons of a specific wavelength to a different wavelength. These applications include solar energy conversion devices and greenhouse roofing materials. With regards to the former, the utilization of solar energy offers a promising alternative energy source to the traditional fossil fuels, and therefore, the development of devices that can convert solar energy into electricity, such as photovoltaic devices (also known as solar cells), has drawn significant attention in recent years. Several different types of mature photovoltaic devices have been developed, including a Silicon based device, a III-V and II- VI PN junction device, a Copper-Indium-Gallium-Selenium (CIGS) thin film device, an organic sensitizer device, an organic thin film device, and a Cadmium Sulfide/Cadmium Telluride (CdS/CdTe) thin film device, to name a few. Information related to these devices can be found in the literature, such as Lin et al, "High Photoelectric Conversion Efficiency of Metal Phthalocyanine/Fullerene Heterojunction Photovoltaic Device" (International Journal of Molecular Sciences 201 1). However, the photoelectric conversion efficiency of many of these devices still has room for improvement and development of techniques to improve this efficiency has been an ongoing challenge for many researchers.

[0004] One technique that may improve the efficiency of photovoltaic devices is to utilize a wavelength down-shifting film. Many of the photovoltaic devices are unable to effectively utilize the entire spectrum of light as the materials on the device absorb certain wavelengths of light (typically the shorter UV wavelengths) instead of allowing the light to pass through to the photoconductive material layer where it is converted into electricity. Application of a wavelength down-shifting film absorbs the shorter wavelength photons and re-emits them at more favorable longer wavelengths, which can then be absorbed by the photoconductive layer in the device, and converted into electricity.

[0005] There have been numerous reports related to the utilization of a wavelength down-shifting material to improve the performance of photovoltaic devices. For example, U.S. Patent Application Publication No. 2009/0151785 relates to a silicon based solar cell which contains a wavelength down-shifting inorganic phosphor material. U.S. Patent Application Publication No. US 2011/0011455 relates to an integrated solar cell comprising a plasmonic layer, a wavelength conversion layer, and a photovoltaic layer. U.S. Patent No. 7,791, 157 relates to a solar cell with a wavelength conversion layer containing a quantum dot compound. U.S. Patent Application Publication No. 2010/0294339 relates to an integrated photovoltaic device containing a luminescent down-shifting material, however no example embodiments were constructed. U.S. Patent Application Publication No. 2010/0012183 relates to a thin film solar cell with a wavelength down-shifting photo- luminescent medium; however, no examples are provided. U.S. Patent Application Publication No. 2008/0236667 relates to an enhanced spectrum conversion film made in the form of a thin film polymer comprising an inorganic fluorescent powder.

[0006] Additionally, wavelength conversion materials have also been used in greenhouse roofing materials. Plants use the energy in sunlight to convert carbon dioxide from the atmosphere, plus water, into simple sugars. These sugars are then used as building blocks and form the main structural component of the plant. It is well known that plants through their development stages react differently to the intensity and wavelengths of the light. According to U.S Patent Application No. 201 1/0016779, plants grow best when exposed to light in the violet-blue region and in the orange-red region, while light in the green region is usually not used by the plant (often reflected by the leaves). Given this knowledge, several techniques have been developed to improve plant growth.

[0007] Several applications exist which relate to the use of luminescent dyes in greenhouse roofing materials to alter the solar spectrum that is incident on the plants within the greenhouse. Japanese patent JP4141025 and Chinese Patent 1380351 relate to the use of a luminescent dye to convert UV wavelengths into blue wavelengths, which can be used in greenhouse roofing materials. Japanese Patents 5227894, 4141025, 7170865, and Chinese Patents 1269393, 1385490, 1 186835, and European Patent 0579835, all relate to methods of using luminescent dyes which convert green wavelengths into red wavelengths, which are incorporated into greenhouse roofing materials to improve plant growth. However, these systems have two major issues. One issue is greenhouses which use photoluminescent dyes often lose a large amount of the emitted light because it remains trapped in the polymeric or glass matrix which comprises the dyes. The second issue is the stability of the dyes, which degrade quickly especially with exposure to UV light.

[0008] Further, some greenhouse roofing materials have attempted to incorporate solar cells or photovoltaic devices, which use a portion of the incident solar radiation to convert to electricity, which can be used for other applications within the greenhouse system. While the utilization of solar energy offers a promising alternative energy source to the traditional fossil fuels, the placement of the photovoltaic modules on greenhouses comes into competition with the plant species for the use of the light available. U.S. Patent Application No. 2013/01 11810 relates to a photovoltaic module for greenhouses which also incorporates a luminescent material to improve the efficiency of photovoltaic devices and enhance the plant growth. However, no examples are given and the luminescent material is not defined.

[0009] While many theories exist on how to improve both the plant growth and obtain sufficient electricity generation with greenhouse roofing materials, we have yet to see successful implementation of these products, specifically because their cost is too high for their limited ability to provide sufficient electrical generation and sustained plant growth. Therefore, a significant amount of development effort is ongoing to find greenhouse roofing materials with photovoltaic devices which provide sufficient electrical generation efficiency and the desired plant growth for an acceptable cost. U.S. Patent 6, 135,665 relates to a polymer sheeting comprising an inorganic luminescent material, yttrium-europium, for use in greenhouses. The use of inorganic luminescent compounds have been shown to be much more photostable. However, the cost to synthesize inorganic luminescent compounds is considerably higher than the cost to synthesize organic luminescent compounds, and therefore may not be economically feasible. However, according to U.S. Patent Application No 2011/0016779, the use of greenhouse roofing materials which incorporate organic luminescent dyes has not been possible due to the poor photostability of these dyes, with the known commercially available dyes exhibiting photobleaching typically within days of exposure to solar radiation.

[0010] While there have been numerous references related to wavelength conversion mediums, their poor photostability has thus far limited their application to the photovoltaic and agriculture industry. Recent efforts to improve the photostability of fluorescent compounds are referred to in the following: U.S. Patent 8,298,677; U.S. Patent 8,513,031 ; U.S. Patent 8,501,301; Y. Kobayashi, K. Misawa, M. Kobayashi, M. Takeda, M. Konno, M. Satake, Y. Kawazoe, N. Ohuchi, and A. Kasuya, "Silica-coating of fluorescent polystyrene microspheres by a seeded polymerization technique and their photo-bleaching property", Colloids and Surfaces A: Physiochem. Eng. Aspects, 242, 47 (2004); U.S. Patent Application No. 13/582,226; and U.S. Patent Application No. 10/542,569. The methods in these references are designed for use in biosubstance labeling (in vitro imaging), and thus are not useful for the photovoltaic and agriculture industries which require films with greater than 3 years of stable wavelength converting function. U.S. Patent Application Nos. 13/978,370 and 13/626,679 to Nitto Denko Inc., relate to novel organic photostable chromophore compounds.

SUMMARY

[0011] Some embodiments include a wavelength conversion film comprising an optically transparent polymer matrix and fluorescent composite particles, wherein the fluorescent composite particles are individually between about 5 nm and 1 μιη in diameter and are dispersed evenly throughout the optically transparent polymer matrix, and wherein the fluorescent composite particles comprise an inorganic oxide matrix and a chromophore, wherein the chromophore is embedded into the inorganic oxide matrix, and wherein the chromophore converts incoming photons of a particular wavelength to a different wavelength. In some embodiments the inorganic oxide matrix comprises silica. The wavelength conversion film may be useful for improving the solar harvesting efficiency of solar energy conversion devices. In some embodiments, the chromophore is an organic dye. In some embodiments, the chromophore is selected from perylene derivative dyes, benzotriazole derivative dyes, benzothiadiazole derivative dyes, diazaborinine derivative dye, or benzo heterocyclic system dyes.

[0012] In some embodiments of the wavelength conversion film, the inorganic oxide matrix is preferably selected from the group consisting of silica, titania, ceria, ytteria, zirconia, alumina, antimony oxide, boron oxide, tin oxide, zinc oxide, or any combination thereof.

[0013] Some embodiments provide a wavelength conversion film. In some embodiments the wavelength conversion film is formed by curing a layer of the photostable wavelength conversion composition disclosed herein.

[0014] In some embodiments, the wavelength conversion film further comprises an additional polymer layer containing a UV absorber, stabilizers, plasticizers, solar absorbers, and/or any combination thereof.

[0015] Some embodiments provide a method of improving the performance of a solar energy conversion device. Solar energy conversion devices include any type of photovoltaic device, solar cell, solar module, or solar panel. In some embodiments, the method of improving the performance of a solar energy conversion device comprises applying the wavelength conversion film disclosed herein, to the light incident surface of the device. In some embodiments, the solar energy conversion device contains a device selected from the group consisting of a III-V or II-VI PN junction device, a Copper-Indium-Gallium- Selenium (CIGS) thin film device, an organic sensitizer device, an organic thin film device, or a Cadmium Sulfide/Cadmium Telluride (CdS/CdTe) thin film device, an amorphous Silicon solar cell, a microcrystalline Silicon solar cell, a crystalline Silicon solar cell, or a polycrystalline Silicon solar cell.

[0016] Some embodiments include a method for increasing the growth rate of a plant. In some embodiments the method for increasing the growth rate of a plant comprises exposing a plant to light that has been filtered through the wavelength conversion film disclosed herein. In some embodiments, the growth rate is increased by about 5% to about 30%, relative to a plant not exposed to light that has been filtered. In some embodiments, a method for increasing the fruit yield of a plant comprises exposing a plant to light that has been filtered through the wavelength conversion film as disclosed herein. In some embodiments, the fruit yield is increased by about 5% to about 30%, relative to a plant not exposed to light that has been filtered.

[0017] Some embodiments include a compound represented by formula (I):

wherein Ri, R2, and R3 comprise and alkyl, a substituted alkyl, or an aryl.

[0018] Some embodiments include a compound represented by formula (Il-a) or (II- b):

wherein:

R is selected from the group consisting of substituted alkyl, optionally substituted alkenyl, optionally substituted cycloalkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted alkoxyalkyl, optionally substituted heteroalkenyl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, and optionally substituted carboxy, optionally substituted carbonyl, optionally substituted ether, optionally substituted ketone, optionally substituted sulfone, and optionally substituted sulfonamide; or R is an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocycloalkyl, or heteroaryl; R ⁴ , R ⁵ , and R ⁶ are independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, optionally substituted cycloalkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted alkoxyalkyl, optionally substituted heteroalkenyl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted heteroarylalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, and optionally substituted carboxy, and optionally substituted carbonyl, optionally substituted ether, optionally substituted ketone, optionally substituted sulfone, and optionally substituted sulfonamide; or R ⁴ and R ⁵ , or R ⁴ and R ⁶ , or R ⁵ and R ⁶ , or R ⁴ and R ⁵ and R ⁶ , together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclalkyl, or heteroaryl; and

L is selected from the group consisting of optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted alkylene, and optionally substituted heteroalkylene, optionally substituted alkynylene, optionally substituted arylene, optionally substituted heteroarylene.

[0019] Some embodiments include a compound represented by a formula:

wherein R ⁴ is C _1-12 alkyl or C _3-12 cycloalkyl; R is -C _a H _2a -R ^* , -CJ O-R ¹ , - CJ COR ¹ , or -CJ OCOR ¹ ; a is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18, 19, or 20; R ^* is optionally substituted C _3-10 cycloalkyl, optionally substituted phenyl, optionally substituted isoindolin-l,3-dion-2-yl, or R ⁿ ; R ¹ is H, optionally substituted C _3-10 cycloalkyl, optionally substituted phenyl, optionally substituted isoindolin-l,3-dion-2-yl, or R ⁿ ; and R ⁿ is C _b H _c N _d O _e , wherein b is 1, 2, 3, 4, 5, 6, 7, or 8; c is 3, 4, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, or 18; d is 0 or 1; and e is 0, 1, 2, 3, or 4.

[0020] Some embodiments include a compound represented by a formula:

w herein is C _1-12 alkyl or C _3-12 cycloalkyl; and L is -CfH ₂ r, wherein f is 1, 2, , 4, 5, 6, 7, or 8.

[0021] Some embodiments include a compound represented by a formula:

-9-

For purposes of summarizing some embodiments and the advantages achieved over the related art, certain objects and advantages of some embodiments are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved by any particular embodiment. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 illustrates an embodiment of a fluorescent composite particle, wherein a chromophore is embedded inside a silica nanoparticle.

[0023] Figure 2 illustrates an embodiment of wavelength conversion film comprising an optically transparent polymer matrix and fluorescent composite particles.

DETAILED DESCRIPTION

[0024] Embodiments include a wavelength conversion (WLC) film. The film comprises a dispersion of fluorescent composite particles capable of converting one photon with a specific wavelength to a different wavelength. The photostability of the chromophore in the WLC film is environmentally sensitive and singlet oxygen molecules often degrade fluorescent chromophore molecules in the excited state. In order for WLC films to be applicable to photovoltaic devices and greenhouses, the wavelength converting function (fluorescence) of the chromophores must remain stable after long-term use/exposure. The inventors found that embedding/impregnating the chromophores into an inorganic oxide matrix significantly improved the photostability of the WLC film by providing protection of the chromophores from various aggressive environments such as sunlight, humidity, and free radicals such as alkoxy radicals caused by organic peroxide decomposition during crosslinking of the film. The wavelength conversion films using the chromophores that were embedded into an inorganic oxide matrix exhibit significantly enhanced photostability compared to wavelength conversion films using chromophores without inorganic oxide matrix protection after a long-term accelerated UV test. The wavelength conversion films with chromophores embedded into the inorganic oxide matrix also showed strong resistance to peroxide decomposition. Prior art might cause a person of ordinary skill in the art to expect that the optical properties of the chromophore may be altered when embedded into a metal oxide matrix such as silica. Surprisingly, the inventors found that the optical properties of the wavelength conversion films are not significantly altered by embedding the chromophores into an inorganic oxide matrix.

[0025] Some embodiments include a wavelength conversion film comprising an optically transparent polymer matrix and fluorescent composite particles. The fluorescent composite particles are individually between about 5 nm and 1 μιη in diameter and are dispersed evenly throughout the optically transparent polymer matrix. The fluorescent composite particles comprise an inorganic oxide matrix and a chromophore, wherein the chromophore is embedded into the inorganic oxide matrix, and wherein the chromophore converts incoming photons of a particular wavelength to a different wavelength.

[0026] The structure of the fluorescent composite particles may vary. In some embodiments the fluorescent composite particles may comprise aggregated or agglomerated particles. In some embodiments, the fluorescent composite particles may comprise non- spherical particles. In some embodiments, the fluorescent composite particles may comprise spherical particles. In some embodiments, the fluorescent composite particles may comprise a chromophore core surrounded by an inorganic oxide matrix shell, wherein the inorganic oxide matrix shell comprises multiple inorganic oxide particles. In some embodiments, the fluorescent composite particles may comprise the chromophore ionically bonded to an inorganic oxide matrix. In some embodiments, the fluorescent composite particles may comprise the chromophore covalently bound inside an inorganic oxide matrix.

[0027] Depending on the application it may be desirable to have the chromophore embedded into the inorganic oxide matrix such that it will not dissolve or leak out of the inorganic oxide matrix with exposure to solvent. In some embodiments, the chromophore is covalently bound inside the inorganic oxide matrix. In some embodiments, to form the fluorescent composite particles, a modified St5ber method may be used. The St5ber method is a physical chemistry process for the generation of particles of silica. The process typically consists of tetraethyl silicate addition to an excess of water containing a low molar-mass alcohol such as ethanol and containing ammonia, the reaction of which forms silica particles. In some embodiments, the St5ber method is modified such that the chromophore is also present in the reaction solution so that the particles are formed with the chromophore covalently embedded into the silica particles. Prior art may cause a person of ordinary skill in the art to expect that the fluorescent properties of the chromophore will be quenched compared to the free dye when it is covalently bound inside an inorganic oxide matrix. However, the inventors have surprisingly found that the fluorescent composite particles comprising a chromophore covalently embedded into silica particles retains its fluorescent properties while also exhibiting increased photostability. In some embodiments, the modified St5ber method is used to synthesize silica nanoparticles with the chromophore permanently embedded into the silica nanoparticle.

[0028] The wavelength conversion film may be improved where there is an even dispersion of chromophore throughout the film with high optical transmission for all visible light. Therefore, it may be helpful for the fluorescent composite particles to be small enough to not significantly block the transmission of light through the film. For example, the material may have a transmittance of at least 50%, 70%, 90%, or 99%. As defined herein, the "diameter" of a particle is the length of a straight line drawn from one point on the particle to a second point on the particle which yields the maximum value for that particle. Particles which have a diameter larger than 1 μιη may cause a decrease in the transmission of light through the film. Therefore, it may be helpful if the fluorescent composite particles are not be larger than 1 μιη in diameter. In some embodiments the fluorescent composite particles are less than 1 μιη in diameter. In some embodiments, the fluorescent composite particles are less than 500 nm in diameter. In some embodiments, the fluorescent composite particles are spherical. In some embodiments, the fluorescent composite particles are non-spherical. In some embodiments, the fluorescent composite particles are spherical or non-spherical nanoparticles of less than 500 nm in diameter. In some embodiments, a fluorescent composite particle may have a diameter of about 1 nm to about 20 nm, about 20 nm to about 40 nm, about 40 nm to about 60 nm, about 60 nm to about 80 nm, about 80 nm to about 100 nm, about 100 nm to about 120 nm, about 120 nm to about 140 nm, about 140 nm to about 160 nm, about 160 nm to about 180 nm, about 180 nm to about 200 nm, about 200 nm to about 220 nm, about 220 nm to about 240 nm, about 240 nm to about 260 nm, about 260 nm to about 280 nm, about 280 nm to about 300 nm, about 300 nm to about 320 nm, about 320 nm to about 350 nm, about 350 nm to about 400 nm, about 400 nm to about 450 nm, or about 450 nm to about 500 nm.

[0029] Figure 1 illustrates an embodiment of a fluorescent composite particle, wherein the chromophore 100 is embedded inside an inorganic oxide matrix 101 comprising a silica nanoparticle, wherein the fluorescent composite particle is less than 1 μιη in diameter, and wherein the chromophore converts incoming photons of a particular wavelength to a different wavelength.

[0030] The inorganic oxide matrix may comprise a variety of materials. In some embodiments, the inorganic oxide matrix comprises silica (or S1O2), titania, ceria, ytteria, zirconia, alumina, antimony oxide, boron oxide, tin oxide, zinc oxide, or any combination thereof. In some embodiments, the inorganic oxide matrix comprises silica. In some embodiments, the silica forms a protective shell around the at least one chromophore. In some embodiments, the mass ratio of silica to chromophore is between about 40 to about 100.

[0031] A variety of materials are possible for use as an optically transparent polymer matrix in the wavelength conversion film. In some embodiments, the optically transparent polymer is selected from the group consisting of ionomer, thermoplastic polyurethane, thermoplastic polyolefin, polymethyl methacrylate, polyvinyl butyral, polydimethyl silicon, ethylene vinyl acetate, ethylene methyl methacrylate, ethylene propylene diene monomer (EPDM), (modified) polyethylene and combinations thereof. In some embodiments, the optically transparent polymer comprises one host polymer, a host polymer and a co-polymer, or multiple polymers. In some embodiments of the wavelength conversion film, the optically transparent polymer may be crosslinkable. In some embodiments, the optically transparent crosslinkable polymer or resin comprises one or more polymers. In some embodiments, the optically transparent crosslinkable polymer is selected from the group consisting of ionomer, thermoplastic polyurethin (TPU), thermoplastic polyolefin (TPO), polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), polydimethyl silicone (PDMS), ethylene vinyl acetate (EVA), ethylene methyl methacrylate (EMMA), and combinations thereof. In some embodiments, the optically transparent crosslinkable polymer comprises one host polymer, a host polymer and a co-polymer, or multiple polymers. Those skilled in the art will appreciate that the use of the term "polymer" herein includes copolymers.

[0032] The refractive index of the optically transparent polymer may vary. In some embodiments the refractive index of the polymer is in the range of about 1.4 to about 1.7. In some embodiments, the refractive index of the optically transparent polymer is in the range of about 1.45 to about 1.55.

[0033] The wavelength conversion film may have a high transmission of visible light, which can be modified by the amount of fluorescent composite particles present in the film. In some embodiments, the fluorescent composite particles are present in the polymer matrix in an amount in the range of about 0.01 wt% to about 3.0 wt%.

[0034] Figure 2 illustrates an embodiment of a wavelength conversion film comprising an optically transparent polymer matrix 102 and fluorescent composite particles 103, wherein the fluorescent composite particles are individually less than 1 μιη in diameter and are dispersed evenly throughout the optically transparent polymer matrix, and wherein the fluorescent composite particles comprise an inorganic oxide matrix and a chromophore, wherein the chromophore is embedded into the inorganic oxide matrix, and wherein the chromophore converts incoming photons of a particular wavelength to a different wavelength.

[0035] Various methods may be used to form the fluorescent composite particles. In some embodiments, the fluorescent composite particles are formed by using a sol gel method. In some embodiments, the fluorescent composite particles comprising silica as the inorganic oxide matrix are formed by using a modified St5ber method.

[0036] In some embodiments, the method of forming the fluorescent composite particles comprising silica as the inorganic oxide matrix is as follows: 1) Dispersing a fluorescent chromophore into a solution (i.e. ethanol, isopropanol, etc.) at a wt. ratio of 1 to 100 to obtain a chromophore solution. In some embodiments, the chromophore dissolves into the solution. In some embodiments, the chromophore does not dissolve into the solution and is instead dispersed into the solution similar to colloids. 2) Place the chromophore solution in an ultrasonicator for 30 min or more to provide even dispersing of the chromophore particles in the solution, and then further stirring the chromophore solution for at least 30 min. 3) Add tetraethoxysilane (TEOS) and isopropanol (IP A) into a round bottom flask at a wt. ratio of 1 to about 10-50 and stir at room temperature for about 5-10 min. In some embodiments, the mole ratio of chromophore to TEOS is about 1 : 4-20. 4) Pour the obtained chromophore solution gradually into the flask and continuously stir the mixture to obtain a homogenous dispersion. 5) Add a trace amount of diethanolamine as a catalyst into the mixture and stir at room temperature for at least 30 min, and then further simultaneously stir and heat the mixture at about 60-100 °C for at least 30 min for gelation. 6) Cool the mixture to obtain precipitates and separate the precipitates by filtration. 7) Wash the filtrate by ethanol, or water to remove the solvent and catalyst completely. 8) Vacuum dry the filtrate at about 100-120 °C for 1-2 hours to obtain a solid powder of the fluorescent composite particles.

[0037] Various methods may be used to incorporate the fluorescent composite particles into the wavelength conversion film. In some embodiments, the wavelength conversion film is formed according to the procedure described below.

General procedure for forming a wavelength conversion film

[0038] In some embodiments, a wavelength conversion film, which comprises fluorescent composite particles and an optically transparent polymer is fabricated by (i) preparing a polymer solution by dissolving polymer powder or pellets in a soluble solvent such as a hydrocarbon, an aromatic hydrocarbon, or an alcohol, or a combination thereof, such as cyclopentanone, dioxane, toluene, etc., at a predetermined ratio; (ii) preparing a fluorescent composite particle solution by dispersing the fluorescent composite particles into the same solvent as the polymer solution at a predetermined concentration; (iii) preparing a wavelength conversion (WLC) solution by mixing the polymer solution with the fluorescent composite particle solution, and (iv) forming the wavelength conversion layer by directly casting the wavelength conversion solution onto a non-stick polymer sheet or transferring the WLC solution to a non-stick PTFE dish, then drying the WLC solution at room temperature for at least 24 hours and further drying the mixture under vacuum at about 40-60 °C for about 3-6 hours, completely removing the remaining solvent by further vacuum hot pressing at about 80-140 °C for 5-10 min; (vi) the film thickness can be adjusted as desired during hot pressing. [0039] In some embodiments, the wavelength conversion film, once formed, is easily attached to a glass or polymer substrate by pressing or laminating. In some embodiments, an adhesive may be needed to attach the wavelength conversion film to the substrate. In some embodiments, once the wavelength conversion film is formed it is adhered to the substrate using an optically transparent and photostable adhesive. In some embodiments the wavelength conversion film may be directly attached to the light incident surface of a solar energy conversion device.

[0040] Once the wavelength conversion film is formed and attached to a substrate (i.e. glass, polymer film, or solar cell), curing can be performed at an elevated temperature to induce crosslinking. In some embodiments, the curing temperature is from about 130 to about 180 degrees Celsius. In some embodiments, the curing time ranges from about 5 minutes to about 90 minutes.

[0041] A luminescent dye, sometimes referred to as a chromophore or fluorescent dye, is a compound that absorbs photons of a particular wavelength or wavelength range, and re-emits the photon at a different wavelength. Since solar cells and photovoltaic devices are often exposed to extreme environmental conditions for long periods of time (i.e. 3+ years for greenhouse panels or 20+ years for photovoltaic devices) the stability of the chromophore is also important. In some embodiments, only luminescent dyes or chromophore compounds with good photostabilty for long periods of time are used in the wavelength conversion composition.

[0042] The amount of chromophore present in the inorganic matrix will also affect the absorption/emission and transmission properties of the film. In some embodiments, the mass ratio of inorganic oxide to chromophore is between about 5 to about 200. In some embodiments, the inorganic matrix is silica, and the mass ratio of silica to chromophore is between about 40 to about 100. In some embodiments the molar ratio of inorganic oxide, such as silica, to chromophore is about 1 to about 100 (or about 1 to about 100 moles of inorganic oxide for each mole of chromophore, about 1 to about 50, about 2 to about 40, about 2 to about 20, about 4 to about 20, about 4 to about 10, about 10 to about 20, about 4, about 8, about 10, or about 20.

[0043] In some embodiments of the wavelength conversion film two or more chromophores are contained in the fluorescent composite particle. In some embodiments of the wavelength conversion film, two or more types of fluorescent composite particles are incorporated into the film, wherein each type of fluorescent composite particle comprises a different chromophore. It may be desirable to have multiple chromophores in the wavelength conversion film, depending on the solar energy conversion device that the material is to be applied. For example, a first chromophore may act to convert photons of wavelengths 300- 400 nm to wavelengths of 500 nm, and a second chromophore may act to convert photons of wavelengths about 500-575 nm to wavelengths of about 600-700 nm, wherein the solar energy conversion device that is to be applied to the film exhibits optimum photoelectric conversion efficiency at about 600-700 nm wavelengths, so that the application of the wavelength conversion film significantly enhances the solar harvesting efficiency of the solar energy conversion device.

[0044] Additionally, in some embodiments of the wavelength conversion film at least one of the chromophores is an up-conversion dye, meaning a chromophore that converts photons from lower energy (long wavelengths) to higher energy (short wavelengths). Up- conversion dyes may include rare earth materials which have been found to absorb photons of wavelengths in the IR region, ~975nm, and re-emit in the visible region (400-700nm), for example, Yb ³⁺ , Tm ³⁺ , Er ³⁺ , Ho ³⁺ , and NaYF ⁴ . U.S. Patent Nos. 6,654, 161, and 6, 139,210, and in the Indian Journal of Pure and Applied Physics, volume 33, pages 169-178, (1995), which are hereby incorporated by reference in their entirety, contain disclosure related to up- conversion materials.

[0045] In some embodiments of the wavelength conversion film at least one of the chromophores is a down-shifting dye, meaning a chromophore that converts photons of high energy (short wavelengths) into lower energy (long wavelengths).

[0046] In some embodiments, the chromophore is an inorganic dye. In some embodiments, the chromophore is an organic dye.

[0047] In some embodiments, the chromophore is an organic dye. In some embodiments, the chromophore is selected from perylene derivative dyes, benzotriazole derivative dyes, diazaborinine derivative dyes, or benzothiadiazole derivative dyes. In some embodiments, the down-shifting chromophore may independently be a derivative of perylene, benzotriazole, benzothiadiazole, benzo heterocyclic systems, and/or combinations thereof, as are described in U.S. Provisional Patent Application Nos. 61/430,053, 61/485,093, 61/539,392, 61/749,225, 62/100,836, and U.S. Pat. Applications Nos. 13/626,679 and 13/978,370, which are hereby incorporated by reference in their entireties. In some embodiments, the wavelength conversion film comprises both an up-conversion chromophore and a down-shifting chromophore.

[0048] As used herein, a "benzotriazole-type structure" includes the following

structural motif: ^N -M N ^N "benzothiadiazole-type structure" includes the

following structural motif: S

[0050] As used herein, a "diazaborinine-type structure" (also known as a

BODIPY or boron-dipyrromethane) includes the following structural motif:

[0051] The term "alkyl" refers to a branched or straight fully saturated acyclic aliphatic hydrocarbon group (i.e. composed of carbon and hydrogen containing no double or triple bonds). Alkyls include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, hexyl, and the like.

[0052] The term "heteroalkyl" used herein refers to an alkyl group comprising one or more heteroatoms. When two or more heteroatoms are present, they may be the same or different.

[0053] The term "cycloalkyl" used herein refers to saturated aliphatic ring system moiety having three to twenty-five carbon atoms including, but not limited to, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like.

[0054] The term "polycycloalkyl" used herein refers to saturated aliphatic ring system moiety having multiple cycloalkyl ring systems.

[0055] The term "alkenyl" used herein refers to a monovalent straight or branched chain moiety of from two to twenty-five carbon atoms containing at least one carbon double bond including, but not limited to, 1-propenyl, 2-propenyl, 2-methyl-l-propenyl, 1-butenyl, 2-butenyl, and the like. [0056] The term "alkynyl" used herein refers to a monovalent straight or branched chain moiety of from two to twenty-five carbon atoms containing a carbon triple bond including, but not limited to, 1-propynyl, 1-butynyl, 2-butynyl, and the like.

[0057] The term "aryl" used herein refers to homocyclic aromatic moiety whether one ring or multiple fused rings. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, phenanthrenyl, naphthacenyl, fluorenyl, pyrenyl, and the like. Further examples include:

naphthalen- 1 -yl naphthalen-2-yl anthracen- 1 -yl anthracen-2-yl anthracen-9-yl

pyren-l-yl perylen-3-yl 9H-fluoren-2-yl

[0058] The term "alkaryl" or "alkylaryl" used herein refers to an alkyl-substituted aryl moiety. Examples of alkaryl include, but are not limited to, ethylphenyl, 9,9-dihexyl- 9H-fluorene, and the like.

[0059] The term "aralkyl" or "arylalkyl" used herein refers to an aryl-substituted alkyl moiety. Examples of aralkyl include, but are not limited to, phenylpropyl, phenylethyl, and the like. [0060] The term "heteroaryl" used herein refers to an aromatic group comprising one or more heteroatoms, whether one ring or multiple fused rings. When two or more heteroatoms are present, they may be the same or different. In fused ring systems, the one or more heteroatoms may be present in only one of the rings. Examples of heteroaryl groups include, but are not limited to, benzothiazyl, benzoxazolyl, quinazolinyl, quinolinyl, isoquinolinyl, quinoxalinyl, pyridinyl, pyrrolyl, oxazolyl, indolyl, thiazyl and the like. Further examples of substituted and unsubstituted heteroaryl rings include:

pyridin-2-yl pyridin-4-yl 2-cyanopyridin-5-yl pyridazin-3-yl pyridazin-4-yl

pyrimidin-2-yl pyrimidin-4-yl pyrazin-2-yl triazin-2-yl

lH-pyrrol- furan-2-yl indol-2-yl indol-3-yl indol- 2-yl yi

benzothiophen- 9H-carbazol-2-yl dibenzofuran-4- dibenzothiophen-

[0061] The term "alkoxy" used herein refers to straight or branched chain alkyl moiety covalently bonded to the parent molecule through an— O— linkage. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, isopropoxy, butoxy, n-butoxy, sec -butoxy, t-butoxy and the like.

[0062] The term "heteroatom" used herein refers to any atom that is not C (carbon) or H (hydrogen). Examples of heteroatoms include S (sulfur), N (nitrogen), O (oxygen), F, CI, Br, and I.

[0063] The term "cyclic amino" used herein refers to either secondary or tertiary amines in a cyclic moiety. Examples of cyclic amino groups include, but are not limited to, aziridinyl, piperidinyl, N-methylpiperidinyl, and the like.

[0064] The term "cyclic imido" used herein refers to an imide wherein the two carbonyl carbons are connected by a carbon chain. Examples of cyclic imide groups include, but are not limited to, 1,8-naphthalimide, pyrrolidine-2,5-dione, lH-pyrrole-2,5-dione, and the likes.

[0065] The term "alcohol" used herein refers to a moiety -OH. [0066] The term "acyl" used herein refers to a moiety -C(=0)R.

[0067] The term "aryloxy" used herein refers to an aryl moiety covalently bonded to the parent molecule through an— O— linkage.

[0068] The term "acyloxy" used herein refers to a moiety -0-C(=0)R.

[0069] The term "carbamoyl" used herein refers to a moiety -C(=0)NH2.

[0070] The term "carbonyl" used herein refers to a functional group C=0.

[0071] The term "carboxy" used herein refers to a moiety -COOR.

[0072] The term "ester" used herein refers to a functional group RC(=0)OR' .

[0073] The term "amido" used herein refers to a moiety -C(=0)NR'R".

[0074] The term "amino" used herein refers to a moiety -NR'R".

[0075] The term "heteroamino" used herein refers to a moiety -NR'R" wherein

R' and/or R" comprises a heteroatom.

[0076] The term "heterocyclic amino" used herein refers to either secondary or tertiary amines in a cyclic moiety wherein the group further comprises a heteroatom.

[0077] The term "cycloamido" used herein refers to an amido moiety of- C(=0)NR'R" wherein R' and R" are connected by a carbon chain.

[0078] The term "sulfone" used herein refers to a sulfonyl moiety of -S(=0)2R.

[0079] The term "sulfonamide" used herein refers to a sulfonyl group connected to an amine group, the moiety of which is -S(=0)2-NR'R".

[0080] As used herein, a substituted group is related to the unsubstituted parent structure in that a substituent group occupies a position occupied by one or more hydrogen atoms in the parent structure. When substituted, the substituent group(s) is (are) one or more group(s) individually and independently selected from C1-C25 alkyl, C2-C25 alkenyl, C2-C25 alkynyl, C3-C25 cycloalkyl (optionally substituted with a moiety selected from the group consisting of halo, alkyl, alkoxy, alcohol, carboxyl, haloalkyl, CN, OH, -SCValkyl, -CF ₃ , and -OCF ₃ ), cycloalkyl geminally attached, C1-C25 heteroalkyl, C3-C25 heterocycloalkyl (e.g., tetrahydrofuryl) (optionally substituted with a moiety selected from the group consisting of halo, alkyl, alkoxy, alcohol, carboxyl, CN, -SCValkyl, -CF ₃ , and -OCF ₃ ), aryl (optionally substituted with a moiety selected from the group consisting of halo, alkyl, arylalkyl, alkoxy, alcohol, aryloxy, carboxyl, amino, imido, amido (carbamoyl), optionally substituted cyclic imido, cylic amido, CN, -NH-C(=0)-alkyl, -CF ₃ ,-OCF ₃ , and aryl optionally substituted with C1-C25 alkyl), arylalkyl (optionally substituted with a moiety selected from the group consisting of halo, alkyl, alkoxy, alcohol, aryl, carboxyl, CN, -S0 ₂ -alkyl, -CF ₃ , and -OCF ₃ ), heteroaryl (optionally substituted with a moiety selected from the group consisting of halo, alkyl, alkoxy, alcohol, aryl, heteroaryl, aralkyl, carboxyl, CN, -SCValkyl, -CF ₃ , and -OCF ₃ ), halo (e.g., chloro, bromo, iodo and fluoro), cyano, hydroxy, optionally substituted cyclic imido, amino, imido, amido, -CF ₃ , C1-C25 alkoxy (optionally substituted with halo, alkyl, alkoxy, aryl, carboxyl, CN, OH, -SCValkyl, -CF ₃ , and -OCF ₃ ), aryloxy, acyloxy, sulfhydryl (mercapto), halo(Ci-C6)alkyl, C1-C6 alkylthio, arylthio, mono- and di-(Ci-C6)alkyl amino, quaternary ammonium salts, amino(Ci-C6)alkoxy, hydroxy(Ci-C6)alkylamino, amino(Ci- C6)alkylthio, cyanoamino, nitro, carbamoyl, keto (oxy), carbonyl, carboxy, acyl, glycolyl, glycyl, hydrazino, guanyl, sulfamyl, sulfonyl, sulfinyl, thiocarbonyl, thiocarboxy, sulfonamide, ester, C-amide, N-amide, N-carbamate, O-carbamate, urea and combinations thereof. Wherever a substituent is described as "optionally substituted" that substituent can be substituted with the above substituents.

[0081] In some embodiments, the chromophore comprises a structure as given by the following general formula (I):

wherein Ri, R2, and R ₃ comprise and alkyl, a substituted alkyl, or an aryl. Example

compounds of general formula (I) include the following:

[0082] In some embodiments, the chromophore comprises a structure as given by the following general formulae (Il-a) and (Il-b):

wherein R in formula Il-a and formula Il-b is selected from the group consisting of C _1-2 s alkyl, C _1-2 s heteroalkyl, C ₂ -25 alkenyl, C3-25 cycloalkyl, polycycloalkyl, heterocycloalkyl, arylalkyl; and R may be optionally substituted with one or more of any of the following substituents: C _1-2 s alkyl, C _1-2 s heteroalkyl, C ₂ -25 alkenyl, C3-25 cycloalkyl, polycycloalkyl, heterocycloalkyl, aryl, heteroaryl, OH, C _m H _2m+ iO ether, C _m H _2m+ iCO ketone, C _m H _2m+ iC0 ₂ carboxylic ester, C e HO-alkyl-C0 ₂ -, C _m H _2m+ iOCO carboxylic ester, ArO aryloxy, ArCO aryl ketone, ArCC^ ester of aryl-carboxylic acid, ArOCO carboxylic ester of phenol, (C _m H _2m+ i)(C _p H _2p+ i) amine, c-(CH ₂ ) _s N amine, (C _m H _2m+ i)(C _p H _2P+ i)NCO amide, c- (CH ₂ ) _s NCO amide, C _m H _2m+ iCON(C _p H ₂ p ₊ i) amide, CN, C _m H _2m+ iS0 ₂ sulfone, sulfonamide, C _m H2 _m+ iS02 (C _p H2 _P+ i) sulfonamide, or c- (CH ₂ ) _s NS0 ₂ sulfonamide, wherein m is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, p is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18, 19, or 20, s is 2, 3, 4, 5, or 6, and Ar is any aromatic or heteroaromatic ring, and Ar is optionally substituted with Ci-4-CO-alkyl or Ci_6-C0 ₂ -alkyl. R ⁴ , R ⁵ , and R ⁶ in formula Il-a and formula Il-b are independently selected from the group consisting of C _1-2 s alkyl, C _1-2 s heteroalkyl, C ₂ -25 alkenyl, C3-25 cycloalkyl, polycycloalkyl, heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, C0 ₂ C _m H _2m+ i carboxylic ester, (C _m H ₂ m ₊ i)(C _p H _2p+ i)NCO amide, c-(CH ₂ ) _s NCO amide, COC _m H _2m+ i ketone, COAr, S0 ₂ C _m H _2m+ i sulfone, S0 ₂ Ar sulfone, (C _m H _2m+ i)(C _p H _2p+ i)S0 ₂ sulfonamide, c-(CH ₂ ) _s S0 ₂ sulfonamide; and R ⁴ , R ⁵ , and R ⁶ are independently optionally substituted with one or more of any of the following substituents: Ci _-2 5 alkyl, Ci-25 heteroalkyl, C ₂ - ₂ 5 alkenyl, C3- ₂ 5 cycloalkyl, polycycloalkyl, heterocycloalkyl, aryl, heteroaryl, OH, C _m H _2m+ iO ether, C _m H _2m+ iCO ketone, C _m H _2m+ iC0 ₂ carboxylic ester, C _m H _2m+ iOCO carboxylic ester, ArO aryloxy, ArCO aryl ketone, ArC0 ₂ ester of aryl carboxylic acid, ArOCO carboxylic ester of phenol, (C _m H _2m+ i)(C _p H _2p+ i)N amine, c-(CH ₂ ) _s N amine, (C _m H _2m+ i)(C _p H _2p+ i)NCO amide, c-(CH ₂ ) _s NCO amide, C _m H _2m+ iCON(C _p H _2p+ i) amide, C _m H _2m+ iS0 ₂ sulfone, (C _m H _2m+ i)(C _p H _2p+ i)NS0 ₂ sulfonamide, C _m H _2m+ iS0 ₂ N(C _p H _2p+ i) sulfonamide, or c-(CH ₂ ) _s NS0 ₂ sulfonamide, wherein m is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, p is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, s is 2, 3, 4, 5, or 6, and Ar is any aromatic or heteroaromatic ring. L in formula Il-b is selected from the group consisting of C _1-2 s alkyl, C _1-2 s heteroalkyl, C ₂ _ ₂ 5 alkenyl; and L may be optionally substituted with one or more of any of the following substituents: C _1-2 s alkyl, C _1-2 s heteroalkyl, C ₂ _ ₂ 5 alkenyl, C3_ ₂ 5 cycloalkyl, polycycloalkyl, heterocycloalkyl, aryl, heteroaryl, OH, C _m H _2m+ iO ether, C _m H _2m+ iCO ketone, C _m H _2m+ iC0 ₂ carboxylic ester, C _m H _2m+ iOCO carboxylic ester, ArO aryloxy, ArCO aryl ketone, ArC0 ₂ ester of aryl- carboxylic acid, ArOCO carboxylic ester of phenol, (C _m H _2m+ i)(C _p H _2p+ i)N amine, c-(CH ₂ ) _s N amine, (C _m H _2m+ i)(C _p H _2p+ i)NCO amide, c-(CH ₂ ) _s NCO amide, C _m H _2m+ iCON(C _p H _2p+ i) amide, CN, C _m H _2m+1 S0 ₂ sulfone, (C _m H _2m+1 )(C _p H _2p+1 )NS0 ₂ sulfonamide, C _m H _2m+1 S0 ₂ N(C _p H _2p+1 ) sulfonamide, or c-(CH ₂ ) _s NS0 ₂ sulfonamide, wherein m is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, p is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, s is 2, 3, 4, 5, or 6, and Ar is any aromatic or heteroaromatic ring.

[0083] With respect to Formula Il-a or Il-b, in some embodiments 1-

12 alkyl, such as CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ , C ₅ H _U , C ₆ H ₁₃ , C ₇ H ₁₅ , C ₈ H ₁₇ , C ₉ H ₁₉ , C ₁₀ H _21> etc.; or C _3-12 cycloalkyl, such as C ₃ H _5; C ₆ Hn _; C ₇ Hi _3; CsHi _5; etc. In some embodiments, . In some embodiments, In some embodiments

In some embodiments, _is

[0084] With respect to Formula Il-a, in some embodiments R is -C _a H _2a -R , C _a H _2a -0-R ^: , -C _a H _2a -COR ^: , or -C _a H _2a -OCOR ^: .

C _a H _2a -COR ^: -C _a H _2a -OCOR ^:

[0085] With respect to -C _a H _2a -R ^* , -C _a H _2a -0-R ^: , -C _a H _2a -COR ^: , or -C _a H _2a -OCOR ^: , a is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20.

[0086] With respect to -C _a H _2a -R ^* , R ^* is H, optionally substituted C _3-10 cycloalkyl, optionally substituted phenyl, optionally substituted isoindolin- 1, 3 -dion-2-yl, or R ⁿ . In some embodiments R is optionally substituted C _3-10 cycloalkyl, optionally substituted phenyl, optionally substituted isoindolin-l,3-dion-2-yl, or R ⁿ .

[0087] With respect to -C _a H _2a -0-R ^: , -C _a H _2a -COR ^: , or -C _a H _2a -OCOR ^: , R ¹ is H, optionally substituted C _3-10 cycloalkyl, optionally substituted phenyl, optionally substituted isoindolin-l,3-dion-2-yl, or R ⁿ . In some embodiments, any substituents of optionally substituted C _3-10 cycloalkyl, optionally substituted phenyl, optionally substituted isoindolin- l,3-dion-2-yl are independently an R ⁿ . R ⁿ is C _b H _{c d} O _e , wherein b is 1, 2, 3, 4, 5, 6, 7, or 8; c is 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18; d is 0 or 1 ; and e is 0, 1, 2, 3, or 4.

[0088] In some embodiments, R or

With respect to Formula Il-b, in some embodiments L is -C _f t½-, wherein f is 1, 2, 3, 4, 5, 6, 7, or !

[0091] In some embodiments, the chromophore comprises a structure as given by the following general formulae (III):

D-,— Het-(-L-Het^-D ₂

' (III)

wherein Het is selected from the group consisting of:

and wherein i is an integer in the range of 0 to 100, X is selected from the group consisting of -N(Ao)-, -0-, -S-, -Se- and -Te-, and Z is selected from the group consisting of -N(R _a )-, -0-, -S-, -Se- and -Te-. Each A ₀ in formula III is selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted acyl, optionally substituted carboxy, and optionally substituted carbonyl. Each R _a , ¾, and R _c , of formula III are independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cycloalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or R _a and ¾, or ¾ and R _c , or R _a and R _c , together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl. Di and D2 are independently selected from the group consisting of hydrogen, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, amido, cyclic amido, and cyclic imido, -aryl-NR'R", -aryl-aryl-NR'R", and -heteroaryl-heteroaryl-R'; wherein R' and R" are independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, optionally substituted aryl; provided that Di and D2 are not both hydrogen, and Di and D2 are not optionally substituted thiophene or optionally substituted furan. L of formula III is independently selected from the group consisting of optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, amino, amido, imido, optionally substituted alkoxy, acyl, carboxy, provided that L is not optionally substituted thiophene or optionally substituted furan.

[0092] In some embodiments, the chromophore comprises a structure as given by the following general formulae (IV-a) and (IV-b):

Het ₂ — A ₀ — Het ₂ (τγ-a) , (IV-b) wherein Het ₂ is selected from the group consisting

from the group consisting of -N(R _a )-, -0-, -S-, -Se- and -Te- Each of the R _a , ¾, and R _c , in formula IV-a and formula IV-b is independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cycloalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or R _a and R _b , or R, and R _c , or R _a and R _c , together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl. Each of the Ra and R _e in formula IV-a and formula IV-b is independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cycloalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or Ra and R _e together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl. Each of Di, D2, D3, and D ₄ in formula IV-a and formula IV-b are each independently Ce-w aryl or optionally substituted Ce-w aryl. The substituent(s) on the Ce-w aryl may be selected from the group consisting of -NR'R", -Ce-w aryl-NR'R", Ci _-8 alkyl and Ci _-8 alkoxy, wherein R' and R" are independently selected from the group consisting of C _1-8 alkyl, C _1-8 alkoxy, Ce- 10 aryl, Ce-w aryl-C _1-8 alkyl, Ce-w aryl-C _1-8 alkoxy, and Ce-w aryl-C(=0)R, wherein R is optionally substituted C _1-8 alkyl, optionally substituted C _1-8 alkoxy or optionally substituted C6-io aryl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to.

[0093] In some embodiments, the chromophore comprises a structure as given by the following general formulae (V-a) and (V-b):

wherein Het ₃ is selected from the group consisting of:

wherein X is selected from the group consisting of -N(A ₀ )-, -0-, -S-, -Se- and -Te- Each A ₀ of formula V-a and formula V-b is selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted acyl, optionally substituted carboxy, and optionally substituted carbonyl. In some embodiments, A ₀ is Ci_s alkyl. Each R _a , R _b , and R _c , of formula V-a and formula V-b is independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cycloalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or R _a and ¾, or ¾ and Rc, or R _a and Rc, together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl. Each Rd and Re of formula V-a and formula V-b is independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cycloalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or Ra and Re together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl. Each Di, D ₂ , D ₃ , and D ₄ of formula V-a and formula V-b is independently selected from the group consisting of hydrogen, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, amido, cyclic amido, and cyclic imido, -aryl-NR'R", -ary-aryl-NR'R", and -heteroaryl-heteroaryl-R'; wherein R' and R" are independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, and optionally substituted aryl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to; provided that Di and D ₂ are not both hydrogen, and Di and D ₂ are not optionally substituted thiophene or optionally substituted furan.

[0094] In some embodiments, the chromophore comprises a structure as given by the following general formula (VI):

wherein D of formula VI is selected from the group consisting of hydrogen, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, amido, cyclic amido, cyclic imido, -aryl-NR'R", -ary-aryl-NR'R", and - heteroaryl-heteroaryl-R' ; wherein R' and R" are independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, and optionally substituted aryl; and wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, optionally substituted cycloalkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted alkoxyalkyl, optionally substituted heteroalkenyl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, and optionally substituted carboxy, optionally substituted carbonyl, optionally substituted ether, optionally substituted ketone, optionally substituted sulfone, and optionally substituted sulfonamide; or R is an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocycloalkyl, or heteroaryl.

[0095] In some embodiments, D in formula VI is selected from the group consisting of phenyl, substituted phenyl, or an aromatic heterocyclic system, and R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are independently selected from phenyl, substituted phenyl, naphthyl, or a heterocyclic system.

[0096] In some embodiments, D in formula VI is selected from furan, thiophene, pyrrole, benzofuran, benzothiophene, indole, carbazole, dibenzofuran, or dibenzothiophene. In some embodiments, D is

[0097] In some embodiments, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ in formula VI are

-37-



39-

-40-

-41-

-43-

[0099] Some embodiments provide a chromophore having the structure of formula VI, wherein D is selected from the group consisting of phenyl, substituted phenyl, or an aromatic heterocyclic system, and R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are independently selected from phenyl, substituted phenyl, naphthyl, or a heterocyclic system, and wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ do not comprise fluorine. In some embodiments, D is selected from furan, thiophene, pyrrole, benzofuran, benzothiophene,

dibenzothiophene. In some embodiments, D is

In some embodiments, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are independently

some embodiments, the structure is any one of the following:

-46-

-47-

-48-

[0100] In some embodiments, the chromophore is present in the wavelength conversion film in an amount in the range of about 0.01 wt% to about 3.0 wt%. In some embodiments, the chromophore is present in the wavelength conversion film in an amount in the range of about 0.05 wt% to about 1.0 wt%.

[0101] Some embodiments include a photostable wavelength conversion film. The wavelength conversion film comprises an optically transparent polymer and fluorescent composite particles. In some embodiments, a wavelength conversion composition may be used to form a wavelength conversion film. In some embodiments the wavelength conversion composition comprises an optically transparent polymer and fluorescent composite particles. In some embodiments, the wavelength conversion composition is cured to form the wavelength conversion film. In some embodiments, curing induces polymerization or crosslinking of the polymer. In some embodiments, the wavelength conversion composition further comprises an adhesion promoter, a stabilizer, a crosslinking coagent, a crosslinking agent, a plasticizer, a solar absorber, or any combination thereof.

[0102] Adhesion promoters are often used in mixtures to improve the compatibility of two or more components in the mixture, or to improve the adhesion between a polymeric system and a filler material (i.e. inorganic material). Adhesion promoters are also known as compatibilizers, or coupling agents. Various adhesion promoters may be used in the wavelength conversion composition. In some embodiments, the adhesion promoter is a polymeric adhesion promoter. In some embodiments, the adhesion promoter comprises an acrylic silane coupling agent, a vinyl silane coupling agent, an epoxy silane coupling agent, or an amino silane coupling agent. In some embodiments, the adhesion promoter comprises 3-Methacryloxypropyltrimethoxysilane, as given by the following formula:

[0103] The concentration of the adhesion promoter may vary depending on the desired properties of the film. In some embodiments, the adhesion promoter is present in the wavelength conversion composition in an amount in the range of about 0.001% to about 2.0% by weight of the composition.

[0104] Stabilizers for polymers are used to prevent the various effects such as oxidation, chain scission, and uncontrolled recombinations and crosslinking reactions that are caused by photo-oxidation of polymers. Stabilizers include antioxidants, UV absorbers, and hindered amine light stabilizers. Polymers are considered to get weathered due to the direct impact of heat and ultraviolet light. The effectiveness of the stabilizers against weathering depends on the ability to stabilize in different polymer matrix, evaporation loss and thermal decomposition during processing and use. Stabilizers are also used to inhibit the reaction between two or more other chemicals. Stabilizers can also inhibit the separation of suspensions, emulsions, and foams. In some embodiments, stabilizers include antioxidants which prevent unwanted oxidation of materials. In some embodiments, an emulsifier or surfactant is used for stabilization of the composition.

[0105] In some embodiments of the composition, the stabilizer comprises a light stabilizer. In some embodiments, an ultraviolet stabilizer is used to protect the film from the harmful effects of ultraviolet radiation. Ultraviolet stabilizers include UV absorbers. Typical UV absorbers are oxanilides for polyamides, benzophenones for PVC, benzotriazoles and hydroxyphenyltriazines for polycarbonate. In some embodiments of the composition, the stabilizer comprises an oxanilide derivative, benzophenone derivative, benzotriazole derivative, hydroxyphenyltriazine derivative, a polymerizable/crosslinkable (meth)acrylic derivative or any combination thereof.

[0106] Other light stabilizers also include scavengers, which are compounds that eliminate the free radicals formed by ultraviolet radiation. Scavenger compounds include hindered amine light stabilizers (HALS). Typical HALS compounds are derivatives of 2,2,6,6-tetramethyl piperidine. Various hindered amine light stabilizer materials may be used in the wavelength conversion composition. In some embodiments, the stabilizer comprises a hindered amine light stabilizer (HALS). In some embodiments, the light stabilizer is a polymerizable compound. In some embodiments, the light stabilizer is a (meth)acrylic compound. In some embodiments, the stabilizer is an H or alkyl-substituted HALS. In some embodiments, the stabilizer is amino-ether (N-OR)-functionalized HALS. In some embodiments, the stabilizer is selected from the group consisting of the commercially available Tinuvin 123, Tinuvin 144, Tinuvin 292, Tinuvin 622, Chimassorb 119, Chimassorb 944, Tinuvin 770, Tinuvin 791, Tinuvin 783, Tinuvin 1 11, Tinuvin NOR371, Adeka Stab LA-57, Adeka Stab LA-63P, Adeka Stab LA-81, and/or Adeka Stab LA-82. The concentration of the stabilizer may vary depending on the desired properties of the film. In some embodiments, the stabilizer is present in the wavelength conversion composition an amount in the range of about 0.001% to about 2.0% by weight of the composition.

[0107] Various crosslinking coagents may be used in the wavelength conversion composition. Coagents, or crosslinking coagents, are used to control the elastic modulus (degree of crosslinking) of the film. These coagents also help to increase the physical and mechanical strengths and photostability of the film. In some embodiments, a nonmetallic Type I coagent and/or a Type II coagent is used in the composition. Type I coagents include trifunctional acrylate, trifunctional methacrylate, zinc diacrylate, zinc dimethacrylate, and N- N'-phenylene dimaleimide. In some embodiments, a Type II coagent is used in the film. Type II coagents include triallyl cyanurate (TAC), triallyl isocyanurate (TAIC) and high vinyl poly(butadiene) (HVPBD). In some embodiments HVPBD may be functionalized with maleic anhydride. In some embodiments, a hybrid coagent is used in the composition. Hybrid coagents include polybutadiene diacrylate (PBDDA). In some embodiments, the coagent comprises an acrylate coagent. In some embodiments, the coagent comprises a methacrylate coagent. In some embodiments, the coagent is selected from the group consisting of ethylene glycol dimethacrylate, trimethyl propane trimethacrylate, Zinc diacrylate, Zinc dimethacrylate, triallyl isocyanuate, high vinyl poly(butadiene), or any combination thereof. Various concentrations of the coagent in the composition may be used, depending on the desired properties of the film. In some embodiments, the coagent is present in the wavelength conversion composition in an amount in the range of about 0.01% to about 10.0% by weight of the composition. In some embodiments, a mixture of Type I and Type II coagents are used in the wavelength conversion composition. For example, in some embodiments the wavelength conversion composition comprises between about 0.01 wt% to about 10.0 wt% of trimethyl propane trimethacrylate, and between about 0.01 wt% to about 10.0 wt% of triallyl isocyanuate.

[0108] In some embodiments, the crosslinking agent comprises an organic peroxide or an amine. Various organic peroxides or amines may be used in the composition. The particular peroxide that is used must be selected to be compatible with the particular components of the wavelength conversion composition. In preferred embodiments, the peroxide or amine added to the composition provides an increase in the photostability of the composition after crosslinking. In some embodiments, the peroxide comprises an organic peroxide. In some embodiments, the peroxide is selected from diacyl peroxides, diakyl peroxides, diperoxyketals, hydroperoxides, ketoneperoxides, peroxydicarbonates, and peroxyesters. In some embodiments, the peroxide is selected from the commercially available group consisting of l, l-di(t-butylperoxy)cyclohexane (Perhexa C), l, l-di(t- hexylperoxy)cyclohexane (Perhexa HC), t-butyl peroxy 2-ethylhexyl monocarbonate (Perbutyl E), n-butyl 4,4-di(t-butyl peroxy) valerate (Perhexa V), Di(2-t-butylperoxy isopropyl) benzene (Perbutyl P), 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (Perhexa 25B), dicumyl peroxide (Percumyl D), or any combination thereof. In some embodiments, the amine comprises an alkyl alkanolamine, an ethanolamines, or an ethyleneamine. The concentration of the peroxide or amine in the composition must also be determined based on the particular components and the desired properties. It is may be desirable for the peroxide to be completely reacted during the crosslinking reaction, such that no peroxide remains in the composition after crosslinking. In some cases, if too much peroxide is used in the composition prior to crosslinking, the remaining peroxide can react with the chromophore and can decrease the photostability of the composition. Typically the use of the peroxide in the composition enables the crosslinking to occur, and increases the photostability of the wavelength conversion composition. If too little peroxide is used in the composition, then the crosslinking reaction will not occur. In some embodiments, the peroxide is present in an amount in the range of about 0.01% to about 3.0% by weight of the composition. In some embodiments, the peroxide is present in an amount in the range of about 0.1% to about 2.0% by weight of the composition.

[0109] In some embodiments, it is useful to incorporate an antioxidant into the wavelength conversion composition. In some embodiments, the wavelength conversion composition further comprises an antioxidant. Antioxidants are used to terminate the oxidation reactions taking place due to different weathering conditions and reduce the degradation of organic materials. For example, synthetic polymers react with atmospheric oxygen. Organic materials undergo auto-oxidizations due to free radical chain reaction. Oxidatively sensitive substrates will react with atmospheric oxygen directly and produce free radicals.

[0110] In some embodiments, it is useful to incorporate a plastisizer into the wavelength conversion composition to soften the hardness of the composition. In some embodiments, the plasticizer content in the composition is 1 to 45 % by weight. In some embodiments the plasticizers include one or more compounds selected from di-2-ethylhexyl sebacate (DOS), di-2-ethylhexyl adipate (DOA), dihexyl adipate (DHA), dibutyl sebacate (DBS), diisononyl adipate (DI A), triethylene glycol-bis-n-heptanoate (3G7), tetraethylene glycol-bis-n-heptanoate (4G7), triethylene glycol-bis-2-ethylhexanoate (3GO or 3G8), tetraethylene glycol-bis-n-2-ethylhexanoate (4GO or 4G8), di-2-butoxy ethyl adipate (DBEA), di-2-butoxyethoxyethyl adipate (DBEEA), di-2-butoxy ethyl sebacate (DBES), di-2- ethylhexyl phthalate (DOP), di-isononyl phthalate (DINP) triethylene glycol-bis- isononanoate, triethylene glycol-bis-2-propyl hexanoate, tris(2-ethylhexyl)phosphate (TOF), 1,2-cyclohexane dicarboxylic acid diisononyl ester (DI CH) and dipropylene glycol benzoate.

[0111] In some embodiments, it is also useful to incorporate a solar absorber such as a phase change material into the wavelength conversion composition to cut out the solar heat.

[0112] Weathering of polymers is caused by absorption of UV light, which results in, radical initiated auto-oxidation. This produces cleavage of hydroperoxides and carbonyl compounds. This may be because of the weak bond in hydro peroxides which is the main source for the free radicals to initiate from. Homolytic decomposition of hydro peroxide can increase the rate of free radicals production. Therefore it may be an important factor in determining oxidative stability. The conversion of peroxy and alkyl radicals to non-radical species terminates the chain reaction, thereby decreasing the kinetic chain length. Hydrogen- donating antioxidants, such as hindered phenols and secondary aromatic amines, inhibit oxidation by competing with the organic substrate for peroxy radicals, thereby terminating the chain reaction and stabilizing the further oxidation reactions. Benzofuranone derivatives are another effective antioxidant, which terminates the chain reaction by donating weakly bonded benzylic hydrogen atom and gets reduced to a stable benzofuranyl (lactone). Antioxidants inhibit the formation of the free radicals thereby enhancing the stability of polymers against light and heat.

[0113] In some embodiments, the antioxidant comprises a phenolic antioxidant, a phosphite antioxidant, a thioether antioxidant, or any combination thereof. In some embodiments, the antioxidant is selected from the commercially available group consisting of Irganox 1010, Irganox 1076, butylated hydroxytoluene (BHT), Irgfos 168, Irganox PS 800, Irganox PS 802, or any combination thereof. In some embodiments, the antioxidant is present in an amount in the range of about 0.001% to about 0.5% by weight of the composition. In some embodiments, the antioxidant is present in an amount in the range of about 0.01% to about 0.1% by weight of the composition.

[0114] Embodiments include a wavelength conversion film formed by curing a layer of the wavelength conversion composition, disclosed herein. In some embodiments, the layer is cured at a temperature of between about 130 to about 180 °C. In some embodiments, the layer is cured at a temperature of between about 145 to about 160 °C. The curing time for the wavelength conversion film depends on the temperature. When the cure temperature is high, the cure time is low, while lower cure temperatures require longer curing times. In some embodiments, the wavelength conversion film is cured for a time of about 5 to about 90 minutes. In some embodiments, the wavelength conversion film is cured for a time of about 10 to about 45 minutes.

[0115] The wavelength conversion film described herein may be prepared in various ways, e.g., by polymerization or crosslinking of the corresponding component monomers or precursors thereof. Polymerization may be carried out by methods known to a skilled artisan, as informed by the guidance provided herein.

[0116] In some embodiments, the wavelength conversion film comprising an optically transparent polymer and fluorescent composite particles, further comprises any of the following: an adhesion promoter, a stabilizer, a crosslinking coagent, and a crosslinking agent (peroxide), or any combination thereof.

[0117] In some embodiments, the wavelength conversion film can be prepared in a conventional manner by free-radical copolymerization with the monomers in suitable solvents, such as, for example, hydrocarbons, such as n-hexane, aromatic hydrocarbons, such as toluene or xylene, halogenated aromatic hydrocarbons, such as chlorobenzene, ethers, such as tetrahydrofuran and dioxane, ketones, such as acetone and cyclohexanone and/or dimethylformamide, and alcohols, at elevated temperatures, in general at from 30 °C to 100 °C, preferably at from 50 °C to 80 °C, if possible in the absence of water and air.

[0118] In some embodiments, the wavelength conversion film can be formed into self-supporting films or layers. However, in some preferred embodiments, the wavelength conversion film can be formed into films or layers that are applied to support materials. This can be carried out by various techniques known in the art. In some embodiments, the method being selected depending on whether a thick or thin film is desired. Thin films can be produced, for example, by spin coating or casting from solutions or melts, while thicker coatings can be produced from prefabricated cells, by hot pressing, calendaring, extruding or injection molding.

[0119] In some embodiments, the wavelength conversion film is formed into a thin film or layer. The method for forming the wavelength conversion film into a thin film may be appropriately selected from known methods used to produce thin films. Specific examples thereof include cast- and calendar-film extrusion, injection molding, roll coating, kiss roll coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, bar coating, knife coating, and air knife coating.

[0120] In some embodiments the wavelength conversion composition may be coated onto an optically transparent substrate. The optically transparent substrate may be plastic or glass.

[0121] In some embodiments the photostability of the fluorescent composite particles can be measured by fabricating a wavelength conversion film containing the fluorescent composite particles and then measuring the absorption peak prior to exposure and after exposure to continuous one sun (AM1.5G) irradiation at ambient temperature. The preparation of such a wavelength conversion film is described in the EXAMPLES section below. The amount of remaining chromophore after irradiation can be measured using the maximum absorption of the chromophore before and after irradiation using the following equation:

Absorption Peak Intensity After Irradiation

x 100% = % Chromophore Remaining

Absorption Peak Intensity Before Irradiation

The % degradation can be measured using the following equation: (Absorption Peak Intensity Before Irradiation - Absorption Peak Intensity After Irradiation)

x 100% = % Chromophore Degraded

Absorption Peak Intensity Before Irradiation

[0122] Easily degraded chromophores typically show a substantial decay of the absorption peak within a few hours of one sun irradiation. Films with excellent photostability will maintain the peak absorption over a long time period of exposure to one sun irradiation. In some embodiments, a photostable chromophore shows less than about 30%, 20%, 15%, 10%, 5%, 2.5%, 1.0%, or 0.5% degradation in maximum absorption peak intensity after 24 hours of continuous one sun (AM1.5G) irradiation at ambient temperature. In some embodiments, a photostable chromophore has greater than about 70%, 80%, 85%, 90%, 95%, 97.5%, 99.0%, or 99.5% of the chromophore remaining (as measured by maximum absorption peak intensity) after 24 hours of continuous one sun (AM1.5G) irradiation at ambient temperature.

[0123] Advantageously, some embodiments of the disclosed polymer matrices of the wavelength conversion film are optically transparent. Optical transparency improves the transmittance of light through the wavelength conversion film allowing more energy to be captured from the light. Additionally, when used as, for example, a window, the additional light that travels through the wavelength conversion film results enhanced brightness through the window. In some embodiments, an optically transparent polymer matrix (absent a chromophore) allows transmission of greater than about 80%, 90%, 95%, 97.5%, 99.0%, 99.5%, or 99.9% of the visible light spectrum.

[0124] The photostable wavelength conversion film comprises an optically transparent polymer and fluorescent composite particles. The photostable wavelength conversion film can be applied to solar energy devices. Because the film is stable for long periods of time when exposed to solar irradiation, it is highly suitable for application to solar energy devices. Solar energy conversion devices include solar cells, solar panels, photovoltaic devices, or any solar module system.

[0125] Solar energy conversion devices employing the wavelength conversion film, disclosed herein, enhances the solar harvesting efficiency of the solar cell device. The wavelength conversion film may be formed to be compatible with all different types of solar cells and solar panels, including Silicon based devices, III-V and II-VI PN junction devices, CIGS thin film devices, organic sensitizer devices, organic thin film devices, CdS/CdTe thin film devices, dye sensitized devices, etc.

[0126] Solar harvesting devices may also be rigid or flexible. Rigid devices include Silicon based solar cells. Flexible solar devices are often made out of organic thin films and may be used on clothing, tents, or other flexible substrates. Therefore, in an embodiment, the wavelength conversion film can be applied to rigid devices or flexible devices.

[0127] Some embodiments provide a method of improving the performance of a solar energy conversion device. Solar energy conversion devices include any type of photovoltaic device, solar cell, solar module, or solar panel. In some embodiments, the method of improving the performance of a solar energy conversion device comprises applying the wavelength conversion film to the light incident surface of the solar energy conversion device. In some embodiments, the solar energy conversion device comprises device selected from the group consisting of a III-V or II-VI PN junction device, a Copper- Indium-Gallium-Selenium (CIGS) thin film device, an organic sensitizer device, an organic thin film device, or a Cadmium Sulfide/Cadmium Telluride (CdS/CdTe) thin film device, an amorphous Silicon solar cell, a microcrystalline Silicon solar cell, a crystalline Silicon solar cell, or a polycrystalline Silicon solar cell. In some embodiments the wavelength conversion film may be cast onto the solar energy conversion device and cured in place. In some embodiments the wavelength conversion film may be in the form of film(s) or layer(s). In some embodiments, the wavelength conversion film, in the form of a thin film, may be roll laminated onto the solar energy conversion devices, wherein only a front layer is laminated onto the solar energy conversion devices, or both a front and back layer are laminated onto the solar energy conversion devices.

[0128] The photostable wavelength conversion film comprises an optically transparent polymer and fluorescent composite particles. The photostable wavelength conversion film can be applied to greenhouse roofing materials. Because the film is stable for long periods of time when exposed to solar irradiation, it is highly suitable for application to greenhouse roofing materials.

[0129] In some embodiments, a method for increasing the growth rate of plants is provided. In some embodiments, wherein the growth rate of a plant that is exposed to light that has been filtered using the wavelength conversion film described above, is increased by about 0 to about 5%, about 5% to about 10%, about 10% to about 20%, about 20% to about 30% about 30% to about 40%, about 40% to about 50%, about 50% to about 60%, about 60% to about 70%, about 70% to about 100%, or over about 100%, values in between or otherwise, relative to a plant not exposed to light that has been filtered.

[0130] Some embodiments provide a method for increasing the growth rate of a plant. In some embodiments the method for increasing the growth rate of a plant comprises exposing a plant to light that has been filtered through the wavelength conversion film disclosed herein. In some embodiments, the growth rate is increased by about 5% to about 30%, relative to a plant not exposed to light that has been filtered. In some embodiments, a method for increasing the fruit yield of a plant comprises exposing a plant to light that has been filtered through the wavelength conversion film as disclosed herein. In some embodiments, the fruit yield is increased by about 5% to about 30%, relative to a plant not exposed to light that has been filtered.

EXAMPLES

[0131] Some embodiments will be explained with respect to certain non-limiting examples. Further, in the present disclosure where conditions and/or structures are not specified, the skilled artisan in the art can readily provide such conditions and/or structures, in light of the teachings herein, as a matter of routine experimentation.

Synthesis of Chromophore

Intermediate A

[0132] Intermediate A was synthesized according to the following reaction scheme: argon

Intermediate A [0133] 4-Bromotriphenylamine (65. Og, 200 mmol) was placed in a 500 ml dry three necked RB flask equipped with a magnetic stirring bar, low temperature thermometer and argon inlet. Tetrahydrofuran was transferred to the reaction flask using a cannula (200 ml) and cooled in a dry-ice acetone bath to -78 °C and n-BuLi 91.6 M in hexane (130 mL) was added dropwise over a period of 30 minutes. The reaction mixture was left to stir at the same temperature for 30 minutes at which time tributyltin chloride (65.0 mL) was added dropwise over 30 minutes. The reaction was left to stir overnight, after which the reaction was allowed to warm to room temperature. The solution was poured into ice-cold water (approximately 500 mL) and extracted using diethyl ether (2 x 250 mL). The organic layer was dried with MgS0 ₄ and the solvent was removed by evaporation to give 106.5 g of Intermediate A as yellowish oil, by ^l H NMR approximately 95% pure.

Intermediate B

[0134] Synthesis of Intermediate B was performed according to the following scheme:

Intermediate B

[0135] Intermediate B was prepared similar to the procedure for Intermediate D, except that neopentyl tosylate was used instead of 1 -iodo-2-methylpropane and potassium carbonate. ^X H NMR for Intermediate B (400 MHz, CDC1 ₃ ): δ 7.53 (d, J=8.8 Hz, 4H), 7.29 (t, J=8.4 Hz, 8H), 7.20 (d, J=8.4 Hz, 12H), 7.05 (t, J=7.0 Hz, 4H), 4.38 (s, 2H), 0.99 (s, 9H).

Intermediate C

[0136] Synthesis of Intermediate C was performed according to the following scheme: argon

[0137] Step 1 : In a three necked reaction flask equipped with argon inlet and magnetic stirring bar, was placed THF (100 mL), Intermediate A (31.1 g, 30 mmol), and argon was bubbled through for approximately 10 minutes before bis(triphenylphosphine)palladium(II) chloride (10% molar per Intermediate A, 1.80 g, 2.5 mmol) was added. The reaction was stirred under argon for 10 minutes before Intermediate B (10.6 g, 25 mmol) was added in one portion. The reaction mixture was refluxed for 22 hours. The reaction was monitored by LCMS and TLC. The reaction was cooled and methanol (200 mL) was added while stirring. A dark orange color solid was formed which was separated by filtration, washed with methanol, and dried to give 4,4'-(2-neopentyl-5,6- dinitro-2H-benzo[d][l,2,3]triazole-4,7-diyl)bis(N,N-diphenyl aniline) (11.5 g, 62%, purity by LCMS 86%).

[0138] Step 2: A mixture of 4,4'-(2-neopentyl-5,6-dinitro-2H- benzo[d][l,2,3]triazole-4,7-diyl)bis(N,N-diphenylaniline) (6.0 g, 8.0 mmol) and iron powder (4.5 g, 80 mmol) was heated and stirred in glacial acetic acid (100 mL) at 130 °C for 2 hours. The reaction was monitored by LCMS and TLC. The reaction was cooled and poured into water to yield yellow solid which was separated by filtration, washed with water and dried to give Intermediate C (4,7-bis(4-(diphenylamino)phenyl)-2-neopentyl-2H- benzo[d][l,2,3]triazole-5,6-diamine) (4.6g, 66%, purity by LCMS 82%). ^X H NMR for nitro intermediate (400 MHz, CDC1 ₃ ): 6 4.66 (s, 2H), 1.08 (s, 9H). ^X H NMR for Intermediate C, 7.43 (d, J=8.8 Hz, 4H),7.31 (t, J=7.0 Hz, 8H), 7.20 (d, J=-8.4 Hz, 8H), 7.1 l(t, J=8.8 Hz, 4H), 4.57 (s, 2H), 1.02 (s, 9H). Intermediate D

[0139] Synthesis of Intermediate D was performed according to the following scheme:

Intermediate C

Intermediate D

[0140] Intermediate C (5.54 g, 8 mmol) was dissolved in 50 mL of THF (for solubility) and 50 mL of acetic acid was added. The mixture was then cooled in an ice/water bath before 12 mL of 1M solution of a C^ in water was added. After 10 minutes the reaction was complete. Diluting with 400 mL of water afforded an orange color solid which was separated by filtration, washed and dried to give Intermediate D, 4,4'-(6-neopentyl-l,6- dihydrobenzo[l,2-d:4,5-d']bis([l,2,3]triazole)-4,8-diyl)bis( N,N-diphenylaniline) ^X H NMR (400 MHz, CDC1 ₃ ): δ 8.0-8.5 (bs, 4H), 7.17-7.35 (m, 20H), 7.02- 7.12 (bs, 4H), 4.66 (s, 2H), 1.11 (s, 9H).

Compound 1

[0141] Synthesis of Compound 1 was performed according to the following procedures:

[0142] Compound 1 was prepared from Intermediate D by alkylation with neopentyl tosylate for one hour at 100°C. The mixture was poured into water and the solid obtained was separated, washed with water, followed by methanol, dried, and purified by column chromatography (dichloromethane/hexane) to give Compound 1. ^X H NMR (400 MHz, DMSO-d ₆ ): δ 8.61 (d, J=8.8 Hz, 4H), 8.16 (s, 4H), 7.33 (m, 8H), 7.08-7.35 (m, 14H), 4.67 (s, 4H), 1.06 (s, 18H). UV-vis spectrum: _max = 522 nm (dichloromethane), Fluorometry: λ = 613 nm (dichloromethane).

Intermediate E

[0143] Common Intermediate E is synthesized using a three step procedure.

E

[0144] Step 1 : 1,6-Dibromohexane ( 64.6 mL, 420 mmol) was added to a slurry of benzotriazole (14.3 g, 120 mmol) and K ₂ C0 ₃ (19.9 g, 144 mmol) in DMF (250 mL). The resulting mixture was stirred at 90 °C under nitrogen for 3 days. After cooling to room temperature, the mixture was worked-up with water and ethyl acetate. The organic layer was separated, dried over magnesium sulfate, and concentrated to dryness. The crude product was purified by silica-gel column chromatography eluting with hexanes/ethyl acetate (95:5); to give 13.05 g of 2-(6-bromohexyl)-2H-benzo[< J[l,2,3]triazole as a colorless solid (yield 38.5 %). ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.83 (m, benzotriazole), 7.37 (m, benzotriazole), 4.77 ( t, J = 7.3 Hz, 2H), 3.37 ( t, J = 6.7 Hz, 2H), 2.12 (m, 2H), 1.2 (m, 2H), 1.47 (m, 2H), 1.38 (m, 2H). [0145] Step 2: A mixture of 2-(6-bromohexyl)-2H-benzo[d][l,2,3]triazole (13 g, 46.06 mmol), bromine (9.05 mL, 176.6 mmol) and 48% HBr (70 mL) was stirred at 130 °C for 16 hours under a refluxed condenser connected with an HBr trap. After cooling to RT, the HBr solution was decanted out to leave a dark sticky oily product. The oil was dissolved in THF/ethyl acetate (1 : 1), washed with ice/water, and treated with a solution of sodium metabisulfite. The organic layer was separated, dried over magnesium sulfate, and concentrated to dryness. The crude product was purified by silica-gel column chromatography eluting with hexanes/ethyl acetate (9: 1 to give 9.8 g of 4,7-dibromo-2-(6- bromohexyl)-2H-benzo[i/][l,2,3]triazole as light yellow oil (yield 48%).

[0146] Step 3 : A solution of K ₂ C0 ₃ (4.83 g, 35 mmol) in H ₂ 0 (15 mL) was added to a mixture of 4,7-dibromo-2-(6-bromohexyl)-2H-benzo[i/][ 1,2,3 ]triazole (4.4 g, 10.0 mmol), 4-t-butylphenyl boronic acid (8.902 g, 50.0 mmol), Pd(PPh ₃ ) ₄ (401 mg, 0.348 mmol), toluene (40 mL), and w-butanol (40 mL) at room temperature under nitrogen. The resultant mixture was stirred at 100 °C under for 3 hours. The mixture was poured into ice/water and extracted with ethyl acetate. The organic layer was separated, passed through Celite, dried over magnesium sulfate, and concentrated to dryness to give a sticky oil. The crude product was purified by column chromatography (silica-gel, eluting with hexanes/DCM (4: 1) to get 3.85 g (70% yield) of colorless solid product, Intermediate E, 2-(6-bromohexyl)-4,7-bis(4- (tert-butyl)phenyl)-2H-benzo[i/][l,2,3]triazole. ^X H NMR (400 MHz, CDC1 ₃ ) : 6 7.99 (d, J = 8.4 Hz, 4H, 4-/-BuC ₆ H ₄ ), 7.61 (s, 2H, benzotriazole), 7.55 (d, J = 8.4 Hz, 4H, 4-/-BuC ₆ H ₄ ), 4.79 (t, J = 7.3 Hz, 2H), 3.39 (t, J = 6.7 Hz ,2H), 2.17 (m, 2H), 1.86 (m, 2H), 1.55-1.30 ( m, 4H), 1.38 (s, 9H).

Compound 2 and 3

[0147] Example Compound 16 and Compound 17 are synthesized according to the following procedure.

[0148] Potassium carbonate (506 mg, 3.7 mmol) was added to a mixture of Intermediate E (1.00 g, 1.83 mmol), glycolic acid (167 mg, 2.2 mmol) and DMF (20 mL). The resultant mixture was stirred at 85 °C under nitrogen for 16 hours. The mixture was poured into ice/water (200 mL) and extracted with ethyl acetate. The extract was dried over magnesium sulfate and concentrated under reduced pressure and subjected to column chromatography (silica-gel, hexanes/ethyl acetate (4: 1) to give Compound 2, 6-(4,7-bis(4- (tert-butyl)phenyl)-2H-benzo[i/][l,2,3]triazol-2-yl)hexyl 2-hydroxyacetate (397 mg, 40% yield), colorless gummy liquid as the first fraction. ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.98 (d, J = 8.4Hz, 4H), 7.61 (s, 2H), 7.54 (d, J = 8.4 Hz, 4H), 4.17 (t, J = 3.6 Hz , 2H), 4.11 (d, J = 5.4 Hz, 2H), 2.19 (t, J = 5.4 Hz, 1H), 2.19-2.15 (m, 2H), 1.68-1.65 (m, 2H), 1.56-1.55 (m, 2H), 1.45-1.41 (m, 4H), 1.38 (s, 18H). ). UV-vis spectrum (PVB film): _max = 344 nm. Fluorimetry (PVB film): _max = 415 nm.

[0149] The second fraction from chromatography gave Compound 3, 6-(4,7-bis(4- (tert-butyl)phenyl)-2H-benzo[i/][l,2,3]triazol-2-yl)hexan-l- ol (294 mg, 29% yield) as colorless crystals. ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.99 (d, J = 8.4Hz, 4H), 7.61 (s, 2H), 7.54 (d, J = 8.4 Hz, 4H), 4.79 (t, J = 3.6 Hz, 2H), 3.65 (q, J = 3.6 Hz, 2H), 2.19-2.15 (m, 2H), 1.59-1.54 (m, 3H), 1.45-1.25 (m, 4H), 1.38 (s, 18H). UV-vis spectrum (PVB film): _max = 344 nm. Fluorimetry (PVB film): _max = 415 nm.

Common intermediate 2 -A

Step 1. 2-Isobutyl-2H-benzo| ^" <f|| ^" 1.2.3 ^" |triazole.

[0150] A mixture of benzotriazole (11.91 g, 100 mmol), l-iodo-2- methylpropane (13.8 mL, 120 mmol), potassium carbonate (41.46 g, 300 mmol), and DMF (200 mL) was stirred and heated under argon at 40 °C for 2 days. The reaction mixture was poured into ice/water (1 L) and extracted with toluene/hexanes (2: 1, 2 x 500 mL). The extract was washed with 1 N HC1 (2 x 200 mL) followed by brine (100 mL), dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The residue was triturated with hexane (200 mL) and set aside at room temperature for 2 hours. The precipitate was separated and discarded, and the solution was filtered through a layer of silica gel (200 g). The silica gel was washed with hexane/DCM/EA (37:50:3, 2 L). The filtrate and washings were combined, and the solvent was removed under reduced pressure to give 2- isobutyl-2H-benzo[i/][l,2,3]triazole (8.81 g, 50% yield) as an oily product. ¾ NMR (400 MHz, CDC1 ₃ ): δ 7.86 (m, 2H, benzotriazole), 7.37 (m, 2H, benzotriazole), 4.53 (d, J = 7.3 Hz, 2H, j-Bu), 2.52 (m, 1H, j-Bu), 0.97 (d, J = 7.0 Hz, 6H, j-Bu).

Step 2. 4.7-Dibromo-2-isobutyl-2H-benzor(iiri.2.31triazole 2-A.

[0151] A mixture of 2-isobutyl-2H-benzo[< J[l,2,3]triazole (8.80 g, 50 mmol), bromine (7.7 mL, 150 mmol) and 48% HBr (50 mL) was heated at 130 °C for 24 hours under a reflux condenser connected with an HBr trap. The reaction mixture was poured into ice/water (200 mL), treated with 5 N NaOH (100 mL) and extracted with DCM (2 x 200 mL). The extract was dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. A solution of the residue in hexane/DCM (1 : 1, 200 mL) was filtered through a layer of silica gel and concentrated to give 4,7-dibromo-2-isobutyl-2H- benzo[i/][l,2,3]triazole 2-A (11.14 g, 63% yield) as an oil that slowly solidified upon storage at room temperature. ^X H NMR (400 MHz, CDC1 ₃ ): δ 7.44 (s, 2H, benzotriazole), 4.58 (d, J = 7.3 Hz, 2H, j-Bu), 2.58 (m, 1H, j-Bu), 0.98 (d, J = 6.6 Hz, 6H, j-Bu).

Step 1. Neopentyl 4-methylbenzenesulfonate.

[0152] To a solution of tosyl chloride (49.72 g, 260.82 mmol) in DCM (520 mL) stirred at room temperature was added 2,2 dimethyl- 1-propanol (21.89 g, 248.4 mmol) followed by triethylamine (35.1 1 mL, 260.82 mmol). The resultant mixture was stirred under nitrogen at ambient temperature for 3 days. The mixture was poured into ice/water (500 mL) and stirred for 1 hour. The organic layer was separated, dried over magnesium sulfate, and concentrated to dryness to give 43 g of a sticky oily product, yield 68 %, which was used in the next step without further purification. ¹ !! NMR (400 MHz, CDC1 ₃ ) : δ 7.76 (d, J = 7.3 Hz, 2H), 7.32 (d, J = 7.3 Hz, 2H), 3.63 (s, 2H, neopentyl), 2.43 ( s, 3H), 0.87 (s, 9H, neopentyl). Step 2. 2-neopentyl-2H-benzor<iiri,2,31triazole.

[0153] Neopentyl 4-methylbenzenesulfonate (30 g, 123.8 mmol) was added at room temperature to a mixture of benzotriazole (17.68 g, 148.54 mmol), potassium carbonate (51.2 g, 371.4 mmol) and DMF (200 mL). The resultant mixture was stirred overnight under nitrogen at 120 °C. After cooling to RT, the mixture was poured into ice/water and extracted with ethyl acetate. The organic layer was separated, dried over magnesium sulfate, and concentrated to dryness. The crude product was purified by silica-gel column chromatography eluting with hexanes/ethyl acetate (95:5) to give 13.83 g of an oily product, yield 59%. ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.83 (m, 2H, benzotriazole), 7.36 (m, 2H, benzotriazole), 4.52 ( s, 2H, neopentyl), 1.05 (s, 9H, neopentyl).

Step 3. 4.7-dibromo-2-neopentyl-2H-benzor<firi.2.31triazole 2-B.

[0154] A mixture of 2-neopentyl-2H-benzo[i/][l,2,3]triazole ( 13.39 g, 70.75 mmol), bromine (7.97 mL, 155.65 mmol) and 48% HBr (70 mL) was stirred at 130 °C for 16 hours under a refluxed condenser connected with an HBr trap. After cooling the reaction mixture to RT, a dark sticky oily product was separated by decantation and dissolved in ice- cold THF/ethyl acetate (1 : 1, 200 mL). The solution was washed with water (100 mL, then treated with sodium 5% metabisulfite (100 mL). The organic layer was separated, dried with magnesium sulfate and concentrated to dryness. The crude product was purified by silica-gel column chromatography eluting with hexanes/ethyl acetate (95:5) and crystallization from MeOH to give 13.5 g of 4,7-dibromo-2-neopentyl-2H-benzo[( J[l,2,3]triazole as a colorless solid (yield 55%). ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.43 (s, 2H, benzotriazole), 4.58 (s, 2H, neopentyl), 1.06 (s, 9H, neopentyl).

Common intermediate 2-C

2-C

Step 1. 2-(6-bromohexyl)-2H-benzor<f||T ,2,3 ^" |triazole.

[0155] 1 ,6-Dibromohexane ( 64.6 mL, 420 mmol) was added to a slurry of benzotriazole (14.3 g, 120 mmol) and K ₂ C0 ₃ (19.9 g, 144 mmol) in DMF (250mL). The resulting mixture was stirred at 90 °C under nitrogen for 3 days. After cooling to RT, the mixture was worked-up with water and ethyl acetate. The organic layer was separated, dried over magnesium sulfate, and concentrated to dryness. The crude product was purified by silica-gel column chromatography eluting with hexanes/ethyl acetate (95:5); to give 13.05 g of 2-(6-bromohexyl)-2H-benzo[i ][ 1,2,3 ]triazole as a colorless solid (yield 38.5 %). *H NMR (400 MHz, CDC1 ₃ ) : δ 7.83 (m, benzotriazole), 7.37 (m, benzotriazole), 4.77 ( t, J = 7.3 Hz, 2H), 3.37 ( t, J = 6.7 Hz, 2H), 2.12 (m, 2H), 1.2 (m, 2H), 1.47 (m, 2H), 1.38 (m, 2H).

Step 2. 4.7-dibromo-2-(6-bromohexyl)-2H-benzo[(il[1.2.31triazole.

[0156] A mixture of 2-(6-bromohexyl)-2H-benzo[d][l,2,3]triazole (13 g, 46.06 mmol), bromine (9.05 mL, 176.6 mmol) and 48% HBr (70 mL) was stirred at 130 °C for 16 hours under a refluxed condenser connected with an HBr trap. After cooling to RT, the HBr solution was decanted out to leave a dark sticky oily product. The oil was dissolved in THF/ethyl acetate (1 : 1), washed with ice/water, and treated with a solution of sodium metabisulfite. The organic layer was separated, dried over magnesium sulfate, and concentrated to dryness. The crude product was purified by silica-gel column chromatography eluting with hexanes/ethyl acetate (9: 1 to give 9.8 g of 4,7-dibromo-2-(6- bromohexyl)-2H-benzo[i/][l,2,3]triazole as light yellow oil (yield 48%).

Step 3. 2-(6-bromohexyl)-4J-bis(4-(tert-butyl)phenyl)-2H-benzor(iiri ,2,31triazole.

[0157] A solution of K ₂ C0 ₃ (4.83 g, 35 mmol) in H ₂ 0 (15 mL) was added to a mixture of 4,7-dibromo-2-(6-bromohexyl)-2H-benzo[<f][ 1,2,3 Jtriazole ( 4.4 g, 10.0 mmol), 4- t-butylphenyl boronic acid (8.902 g, 50.0 mmol), Pd(PPh ₃ ) ₄ ( 401 mg, 0.348 mmol), toluene (40 mL), and w-butanol (40 mL) at RT under nitrogen. The resultant mixture was stirred at 100 °C under for 3 hours. The mixture was poured into ice/water and extracted with ethyl acetate. The organic layer was separated, passed through Celite, dried over magnesium sulfate, and concentrated to dryness to give a sticky oily. The crude product was purified by column chromatography (silica-gel, eluting with hexanes/DCM (4: 1) to get 3.85 g (70% yield) of colorless solid product. ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.99 (d, J = 8.4 Hz, 4H, 4-t- BuC ₆ H ₄ ), 7.61 (s, 2H, benzotriazole), 7.55 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 4.79 (t, J = 7.3 Hz, 2H), 3.39 (t, J = 6.7 Hz ,2H), 2.17 (m, 2H), 1.86 (m, 2H), 1.55-1.30 ( m, 4H), 1.38 (s, 9H).

Common intermediate 2-D

Step 1. 4,7-Dibromo-2H-benzor(iiri,2,31triazole.

[0158] A mixture of benzotriazole (1 1.91 g, 100 mmol), 48% hydrobromic acid (100 mL) and bromine (11.5 mL, 225 mmol) was heated at 130 °C for 48 hours under a reflux condenser connected with an acid trap. The reaction mixture was poured onto crushed ice (300 g). When the ice melted, the mixture was decolorized with 10% sodium hydrogen sulfite. The precipitate was filtered off, washed with water (100 mL) and dissolved in hot methanol (100 mL). The methanolic solution was poured into water (300 mL), and the mixture was stirred for 30 min. The precipitate was filtered off and dried to give crude 4,7- Dibromo-2H-benzo[i/][l,2,3]triazole that was used in the next step without further purification.

Step 2. 4.7-dibromo-2-(tetrahydro-2H-pyran-2-yl)-2H-benzo[(il[1.2.31 triazole.

[0159] A solution of the crude material from step 1 in THF (100 mL), 3,4- dihydro-2H-pyran (10.9 mL, 120 mmol) and p-TSA (1.00 g) was heated at reflux for 3 hours. The reaction mixture was poured onto crushed ice (200 g), treated with saturated aHC03 (200 mL) and extracted with DCM (2x200 mL). The extract was dried over MgSC^, and the solvent was removed under reduced pressure. Column chromatography of the residue (silica gel, hexanes/ethyl acetate, 4: 1) gave 4,7-dibromo-2-(tetrahydro-2H-pyran-2-yl)-2H- benzo[i/][l,2,3]triazole (8.78 g of purity 64%). Yield 15% for 2 steps. ¾ NMR (400 MHz, CDC1 ₃ ) : δ 7.45 (s, 2H, benzotriazole), 6.10 (dd, J = 8.8 and 2.6 Hz, 1H), 4.12 (m, 1H), 3.82 (m, 1H), 2.59 (m, 1H), 2.16 (m, 2H), 1.80 (m, 2H), 1.69 (m, 1H).

Step 3, 4.7-bis(4-(tert-butyl)phenyl)-2-(tetrahvdro-2H-pyran-2-yl)-2 H- benzordiri ,2,31triazole.

[0160] A mixture of the product from step 2 (15.5 mmol), A-tert- butylphenylboronic acid (8.90 g, 50 mmol), potassium carbonate (8.28 g, 60 mmol), water (15 mL), tetrakis(triphenylphosphine)palladium(0) (2.00 g), isobutyl alcohol (70 mL), and toluene (30 mL) was stirred under argon and heated at 100 °C for 20 hours. The reaction mixture was poured into ice/water (400 mL) and extracted with ethyl acetate (400 mL). The extract was washed with brine (200 mL), dried over a ₂ C0 ₃ , and the solvent was removed under reduced pressure. Chromatography of the residue (silica gel, hexanes/DCM, 3:2) afforded 4,7-bis(4-(ter?-butyl)phenyl)-2-(tetrahydro-2H-pyran-2-yl)-2 H- benzo[i/][l,2,3]triazole (5.43 g, purity 90%). Yield: 75%. ^X H NMR (400 MHz, CDC1 ₃ ): δ 8.02 (d, J = 8.4 Hz, 4H, 4-tert-butylphenyl), 7.64 (s, 2H, benzotriazole), 7.53 (d, J = 8.4 Hz, 4H, 4-tert-butylphenyl), 6.13 (dd, J = 8.7 and 2.9 Hz, 1H), 4.14 (m, 1H), 3.82 (m, 1H), 2.67 (m, 1H), 2.20 (m, 2H), 1.80 (m, 2H), 1.72 (m, 1H), 1.38 (s, 18H, 4-tert-butylphenyl).

Step 4. 4.7-bis(4-(ter?-butyl)phenyl)-2H-benzordiri .2.31triazole.

[0161] A mixture of 4,7-bis(4-(tert-butyl)phenyl)-2-(tetrahydro-2H-pyran-2-yl)- 2H-benzo[< J[l,2,3]triazole (10.5 mmol), Montmorillonite K-10 and THF (50 mL) was heated at reflux for 16 hours. The solid was filtered off and washed thoroughly with THF (100 mL).

[0162] Combined filtrate and washings were concentrated under reduced pressure, and the residue was triturated with methanol (20 mL) to give 4,7-bis(4-(tert-butyl)phenyl)- 2H-benzo[d][l,2,3]triazole of high purity as colorless cubes (3.80 g, 94% yield). ^X H NMR (400 MHz, CDC1 ₃ ): δ 12.27 (bs, 1H, NH), 8.07 (bm, 4H, 4-tert-butylphenyl), 7.61 (s, 2H, benzotriazole), 7.58 (d, J = 8.1 Hz, 4H, 4-tert-butylphenyl), 1.39 (s, 18H, 4-tert-butylphenyl).

Common intermediate 2-E

[0163] A mixture of intermediate D (1.00 g, 2.60 mmol), 1,4-dibromobutane (31 mL, 26 mmol), K2CO3 (2.76 g, 20 mmol), and NMP (5 mL) was stirred under argon and heated at 100 °C for 24 hours. The reaction mixture was poured into water (200 mL) and extracted with hexanes/ethyl acetate (1 : 1, 300 mL). The extract was washed with water (200 mL), dried over MgS0 ₄ , and the solvent was removed under reduced pressure. The crude product was purified by column chromatography (silica gel, hexanes/ethyl acetate, 3 : 1) to give 2-(4-bromobutyl)-4,7-bis(4-(tert-butyl)phenyl)-2H-benzo[i ][l,2,3]triazole (2-E) of purity 75% (1.14 g, 63% yield). The material was used in the following step without further purification. ^X H NMR (400 MHz, CDC1 ₃ ): δ 7.98 (d, J = 8.4 Hz, 4H, 4-tert-butylphenyl), 7.62 (s, 2H, benzotriazole), 7.54 (d, J = 8.4 Hz, 4H, 4-tert-butylphenyl), 4.84 (t, J = 7.0 Hz, 2H), 3.47 (t, J = 6.6 Hz, 2H), 2.34 (m, 2H), 1.95 (m, 2H) 1.39 (s, 18H, 4-tert-butylphenyl).

Common intermediate 2-F

2-F

[0164] A mixture of intermediate 2-D (1.96 g, 5.1 mmol), pentaerythritol tetrabromide (5.00 g, 12.9 mmol), K ₂ C0 ₃ (8.28 g, 6.0 mmol) and NMP (20 mL) was stirred under argon and heated at 80 °C for 20 hours. The reaction mixture was poured into water (200 mL) and stirred for 1 hour. The obtained precipitate was filtered off, washed with water (50 mL), dried in a vacuum oven and purified by column chromatography (silica gel, hexanes/DCM, 3:2) to give 2-(3-bromo-2,2-bis(bromomethyl)propyl)-4,7-bis(4-(tert- butyl)phenyl)-2H-benzo[i/][l,2,3]triazole (2.51 g, 71% yield). ^X H NMR (400 MHz, CDC1 ₃ ): δ 8.03 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 7.69 (s, 2H, benzotriazole), 7.55 (d, J = 8.4 Hz, 4H, 4-t- BuC ₆ H ₄ ), 5.13 (s, 2H), 3.67 (s, 6H), 1.39 (s, 18H, 4-?-BuC ₆ H ₄ ).

[0165] A mixture of intermediate 2-A (purity 90%, 2.89 g, 7.8 mmol), A-(tert- butyl)phenylboronic acid (4.00 g, 22 mmol), potassium carbonate (5.52 g, 40 mmol), water (6 mL), toluene (20 mL), and w-butanol (40 mL) was stirred under argon and heated to 75 °C. Tetrakis(triphenylphosphine)palladium(0) (1.00 g, 0.86 mmol) was added and the whole mixture was heated under argon at 100°C for 4 hours. The reaction mixture was poured into water (200 mL), and extracted with ethyl acetate/toluene/THF (2:2: 1, 500 mL). The extract was washed with water (100 mL), and the volatiles were thoroughly removed under reduced pressure. Column chromatography of the residue (silica gel, hexane/DCM, 3 : 1) followed by crystallization from ethanol (50 mL) gave pure 4,7-bis(4-(/er/-butyl)phenyl)-2-isobutyl-2H- benzo[i/] [l ,2,3]triazole (2.57 g, 75% yield). ^X H NMR (400 MHz, CDC1 ₃ ): δ 7.99 (d, J = 8.4 Hz, 4H, 4-/-BuC ₆ H ₄ ), 7.60 (s, 2H, benzotriazole), 7.54 (d, J = 8.4 Hz, 4H, 4-/-BuC ₆ H ₄ ), 4.59 (d, J = 7.7 Hz, 2H, j-Bu), 2.60 (m, 1H, j-Bu), 1.38 (s, 18H, 2 f-Bu), 1.01 (d, J = 6.6 Hz, 6H, i- Bu). UV-vis spectrum (PVB film): _max = 346 nm. Fluorimetry (PVB film): _max = 415 nm.

Example 2-2. 4,7-bis(4-(ter/-butyl)phenyl)-2-neopentyl-2H-benzor( iri,2,31triazole.

[0166] Following a procedure analogous to that described in Example 2- 1, reaction of intermediate 2-B with 4-(/er/-butyl)phenylboronic acid gave 4,7-bis(4-(/er/- butyl)phenyl)-2-neopentyl-2H-benzo[if| [ l,2,3]triazole in 75% yield. ^X H NMR (400 MHz, CDC1 ₃ ): δ 8.00 (d, J = 8.1 Hz, 4H, 4-/-BuC ₆ H ₄ ), 7.62 (s, 2H, benzotriazole), 7.54 (d, J = 8.0 Hz, 4H, 4-/-BuC ₆ H ₄ ), 4.61 (s, 2H, neopentyl), 1.38 (s, 18H, 2 f-Bu), 1.12 (s, 9H, neopentyl). UV-vis spectrum (PVB film): _max = 347 nm. Fluorimetry (PVB film): _max = A ll nm.

Example 2-3. 2-Isobutyl-4.7-bis(4-(2-methylhexan-2-yl)phenyl)-2H-benzor(i iri.2.31triazole.

Step 1. 4-(2-methylhexan-2-yl)phenol. [0167] A mixture of 2-methyl-2-hexanol (13 mL, 90.8 mmol), phenol (7.77 g, 82.6 mmol) in trifluoroacetic acid (25 mL) was stirred at 85 °C for 16 hours. TFA was removed by evaporation under reduced pressure to gain 15.8 g of dark color oil, which was dissolved into diethyl ether (250 mL), washed with sat. aHC03, dried over Na ₂ S0 ₄ , and concentrated to dryness to gain 14.85 g of a crude product. The crude product was purified by silica-gel column chromatography with hexanes: ethyl acetate(95/5) as an eluent to give 7.16 g of pure colorless oil (yield 45%).

Step 2. 4-(2-methylhexan-2-yl)phenyl trifluoromethanesulfonate.

[0168] Triflic anhydride (6.79 mL, 40.42 mmol) was added dropwise to a mixture of 4-(2-methylhexan-2-yl) phenol (7.16 g, 37.23 mmol), pyridine (3.28 mL, 40.86 mmol) in dichloromethane (45 mL) at -10 °C. The resultant mixture was stirred at -10°C under nitrogen atmosphere for 15 minutes. The cooling bath was removed, and the reaction mixture was stirred at room temperature overnight. The mixture was poured into ice/water and then extracted with dichloromethane. The organic layer was separated, dried over Na ₂ S0 ₄ ,and concentrated to dryness to give 11.66 g of a brown-color oily product (yield 96.5%). The crude product was used in the next step without further purification.

Step 3. 4.4.5.5-tetramethyl-2-(4-(2-methylhexan-2-yl)phenyl)-1.3.2-d ioxaborolane.

[0169] Potassium acetate (5.6 g, 53.91 mmol) was added to a mixture of PdCl ₂ (dppf)( 0.636 g, 0.718 mmol), bispinacolato diboron (10.95 g, 43.13 mmol) and 4-(2- methylhexan-2-yl)phenyl trifluoromethane -sulfonate (1 1.66 g, 35.94 mmol) in 1, 4 dioxane (65 mL) at room temperature. To remove air, argon was bubbled through the resultant mixture for 10 minutes before heating at 85 °C overnight. After cooling to RT, the mixture was poured into ice/water and extracted with ethyl acetate. The organic layer was separated, passed through a layer of Celite, dried over a ₂ C0 ₃ , and concentrated to dryness. The crude product was purified by silica-gel column chromatography, eluent hexanes/ethyl acetate (95:5), to give 7g of oily product, yield 64 %.

Step 4. 2-Isobutyl-4,7-bis(4-(2-methylhexan-2-yl)phenyl)-2H-benzor( i r L2,31triazole.

[0170] A solution of potassium carbonate (1.65 g, 12 mmol) in H ₂ 0 (5 mL) was added to a mixture of Pd(PPh ₃ ) ₄ ( 69.3 mg, 0.06 mmol), 4,4,5,5-tetramethyl-2-(4-(2- methylhexan-2-yl)phenyl)-l,3,2-dioxaborolane (2.08 g, 6.9 mmol) and 4,7-dibromo-2- isobutyl-2H-benzo[d][l,2,3]triazole ( lg, 3 mmol) in toluene (20 mL) and n BuOH (30 mL) at room temperature. The resultant mixture was bubbled with argon for 10 minutes before stirred at 85 °C under Nitrogen atmosphere overnight. After cooling to RT the mixture was poured into ice/water and extracted with ethyl acetate. The organic layer was separated, passed through a layer of Celite, dried over a ₂ C0 ₃ , and concentrated to dryness. The crude product was purified by silica-gel column chromatography, eluent hexanes/ethyl acetate (98:2), to give 1.2 g of colorless solid product, yield 82 %. ^X H NMR (400 MHz, CDC1 ₃ ): δ 8.02 (d, J = 8.4 Hz, 4H, 4-/-octyl-C ₆ H ₄ ), 7.63 (s, 2H, benzotriazole), 7.47 (d, J = 8.4 Hz, 4H, 4-/-octylC ₆ H ₄ ), 4.60 (d, J = 7.3 Hz, 2H, j-Bu), 2.62 (m, 1H, j-Bu), 1.65 (m, 4H, /-octyl), 1.34 (s, 12H, t-octyl), 1.24 (quintet, J = 7.0 Hz, 4H, t-octyl), 1.11 (m, 4H, t-octyl), 1.02 (d, J = 6.6 Hz, 6H, j-Bu), 0.84 (t, J = 7.1 Hz, 6H, /-octyl). UV-vis spectrum (PVB film): _max = 348 nm. Fluorimetry (PVB film): _max = 417 nm.

Exampl -4. 2-Isobutyl-4.7-bis(4-(l-methylcvclohexyl)phenyl)-2H-benzor( iri.2.31triazole.

[0171] Starting from 1 -methylcyclohexanol, 2-isobutyl-4,7-bis(4-(l- methylcyclohexyl)phenyl)-2H-benzo[( J[l,2,3]triazole was obtained using a procedure analogous to that in Example 2-3. ^X H NMR (400 MHz, CDC1 ₃ ): δ 8.03 (d, J = 8.4 Hz, 4H, 4- c-hexyl-C ₆ H4), 7.63 (s, 2H, benzotriazole), 7.51 (d, J = 8.4 Hz, 4H, 4-c-hexylC ₆ H ₄ ), 4.60 (d, J = 7.3 Hz, 2H, j-Bu), 2.62 (m, 1H, j-Bu), 2.02 (m, 4H, c-hexyl), 1.58 (m, 8H, c-hexyl), 1.49 (m, , 8H, c-hexyl), 1.24 (s, 6H, c-hexyl), 1.02 (d, J = 6.6 Hz, 6H, i-Bu). UV-vis spectrum (PVB film): _max = 348 nm. Fluorimetry (PVB film): _max = 419 nm.

Example 2-5. 4J-bis(4-(l-methylcvclohexyl)phenyl)-2-neopentyl-2H- benzor<fUT ,2,31triazole.

[0172] Starting from 1 -methylcyclohexanol and intermediate 2-B, 4,7-bis(4-(l- methylcyclohexyl)phenyl)-2-neopentyl-2H-benzo[i/][l,2,3]tria zole was obtained using a procedure analogous to that in Example 2-3. ^l R NMR (400 MHz, CDC1 ₃ ): δ 8.04 (d, J = 8.4 Hz, 4H, 4-c-hexyl-C ₆ H ₄ ), 7.64 (s, 2H, benzotriazole), 7.52 (d, J = 8.4 Hz, 4H, 4-c- hexylC ₆ H ₄ ), 4.61 (s, 2H, neopentyl), 2.06 (m, 4H, c-hexyl), 1.61 (m, 8H, c-hexyl), 1.49 (m, , 8H, c-hexyl), 1.24 (s, 6H, Me-c-hexyl), 1.13 (s, 9H, neopentyl). UV-vis spectrum (PVB film): _max = 348 nm. Fluorimetry (PVB film): _max = 418 nm.

Example 2-6. 4.7-bis(4-(2-methylhexan-2-yl)phenyl)-2-neopentyl-2H-benzord iri .2.31- triazole.

[0173] This chromophore was obtained by a procedure analogous to that described in Example 2-3 using intermediate 2-B in the last step instead of intermediate 2-A. ¾ NMR (400 MHz, CDC1 ₃ ): δ 8.03 (d, J = 8.4 Hz, 4H, 4-?-octyl-C ₆ H ₄ ), 7.64 (s, 2H, benzotriazole), 7.47 (d, J = 8.4 Hz, 4H, 4-t-octylC ₆ H ₄ ), 4.61 (s, 2H, neopentyl), 1.65 (m, 4H, i-octyl), 1.34 (s, 12H, i-octyl), 1.24 (quintet, J = 7.0 Hz, 4H, i-octyl), 1.13 (s, 9H, neopentyl), 1.11 (m, 4H, i-octyl), 0.84 (t, J = 7.3 Hz, 6H, i-octyl). UV-vis spectrum (PVB film): _max = 348 nm. Fluorimetry (PVB film): _max = 418 nm.

Example 2 L 4.7-bis(4-(3.7-dimethyloctan-3-yl)phenyl)-2-isobutyl-2H- benzordiri .2.31triazole.

[0174] This chromophore was obtained from 3,7-dimethyloctan-3-ol following the procedure given in Example 2-3. ¾ NMR (400 MHz, CDC1 ₃ ): δ 8.02 (d, J = 8.4 Hz, 4H, C ₆ H ₄ ), 7.63 (s, 2H, benzotriazole), 7.47 (d, J = 8.4 Hz, 4H, C ₆ H ₄ ), 4.60 (d, J = 7.3 Hz, 2H, i- Bu), 2.62 (m, 1H, j-Bu), 2.62 (m, lH, j-Bu), 1.64 (m, 2H, 4-methylpentyl), 1.34 (s, 6H, methyl), 1.30-1.16 (m, 12H, 4-methylpentyl), 1.08 (m, 4H, ethyl), 1.02 (d, J = 6.6 Hz, 6H, i- Bu), 0.80 (t, J = 7.0 Hz, 6H, ethyl), 0.79 (d, J = 7.3 Hz, 12H, 4-methylpentyl. UV-vis spectrum (PVB film): m _ax = 347 nm. Fluorimetry (PVB film): _max = A ll nm.

Example 2-8

Step 1. Methyl 2,2-dimethyrtetradecanoate.

[0175] The starting ester was prepared by alkylation of methyl isobutyrate with 1- iodododecane in THF using LDA as a base.

Step 2. 2,2-Dimethyrtetradecan-l-ol.

[0176] Pellets of LiAlH ₄ (7.72 g, 203 mmol) were added portion-wise to a solution of crude methyl 2,2-dimethyltetradecanoate (purity 85%, 24.40 g, 76.7 mmol) in THF (200 mL) that was stirred and cooled in a water bath. After addition, the cooling bath was removed, and the mixture was heated at reflux for 2 hours. After cooling to room temperature, the reaction mixture was treated with 20% NaOH (50 mL) and extracted with ethyl ether (200 mL). The extract was dried over Na ₂ S0 ₄ , and the solvent was removed under reduced pressure to give 2,2-dimethyltetradecan-l-ol (purity 90%, 19.24 g), 93% yield. 1H NMR (400 MHz, CDC1 ₃ ) : 6 3.30 (s, 2H), 1.30 (m, 2H), 1.27 (m, 16H), 1.21 (m, 2H), 0.90 (m, 2H), 0.86 (t, J = 7.0 Hz, 3H), 0.84 (s, 6H).

Step 3. 2.2-dimethyltetradecyl 4-methylbenzenesulfonate.

[0177] A solution of 2,2-dimethyltetradecan-l-ol (90%, 7.27 g, 30 mmol), tosyl chloride (5.60 g, 29 mmol) and triethylamine (4.9 mL, 35 mmol) in DCM (100 mL) was heated at 35 °C for 16 hours. The reaction mixture was poured into ice/water (500 mL) and extracted with DCM (500 mL). The extract was dried over MgS0 ₄ , and the solvent was removed under reduced pressure to give 2,2-dimethyltetradecyl 4-methylbenzenesulfonate (purity 80%, 1 1.75 g) as an oil, yield 98%. ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.91 (d, J = 8.2 Hz, 2H), 7.40 (d, J = 8.2 Hz, 2H), 3.30 (s, 2H), 2.48 (s, 3H, tosylate), 1.30 (m, 2H), 1.25 (m, 18H), 1.21 (m, 2H), 0.87 (t, J = 7.0 Hz, 3H), 0.85 (s, 6H).

Step 4. 4.7-bis(4-(tert-butyl phenyl -2-(2.2-dimethyltetradecyl -2H- benzoin .2.31triazole.

[0178] A mixture of 2,2-dimethyltetradecyl 4-methylbenzenesulfonate (80%, 740 mg, 1.5 mmol), intermediate C (383 mg, 1.0 mmol), K2CO ₃ (690 mg, 5 mmol), and DMF (7 mL) was stirred under argon and heated at 120 °C for 22 hours. The reaction mixture was poured into ice/water (300 mL) and extracted with DCM (2 x 200 mL). The extract was dried over MgS0 ₄ , and the solvent was removed under reduced pressure. The residue was chromatographed (silica gel, hexanes/ethyl acetate, 3 : 1). The material eluted as the first fraction was crystallized from methanol (20 mL) to give 4,7-bis(4-(tert-butyl)phenyl)-2-(2,2- dimethyltetradecyl)-2H- benzo[<i][l,2,3]triazole (330 mg, 27% yield) as white crystals. ^X H NMR (400 MHz, CDC1 ₃ ) : 6 8.01 (d, J = 8.2 Hz, 4H, 4-(tert-butyl)phenyl), 7.62 (s, 2H. benzotriazole), 7.53 (d, J = 8.2 Hz, 2H 4-(tert-butyl)phenyl), 4.61 (s, 2H), 1.47 (m, 2H), 1.38 (s, 18H, 4-(tert-butyl)phenyl), 1.33 (m, 8H), 1.27 (m, 12H), 1.06 (s, 6H), 0.87 (t, J = 6.8 Hz, 3H). UV-vis spectrum (PVB film): _max = 347 nm. Fluorimetry (PVB film): _max = 416 nm.

Example 2-8. 4.7-Bis(4-(ter?-butyl)phenyl)-2-decyl-2H-benzor(iiri.2.31tri azole.

[0179] A mixture of intermediate 2-D (600 mg, 1.56 mmol), 1 -bromodecane (1.0 mL, 5.0 mmol), K2CO3 (1.38 g, 10 mmol) and DMF (10 mL) was stirred under argon and heated at 120 °C for 5 hours. The reaction mixture was poured into water (200 mL) and extracted with hexanes/ethyl acetate (1 :2, 200 mL). The extract was washed with water (100 mL), dried over magnesium sulfate and the solvent was removed under reduced pressure. The crude product was purified by column chromatography (silica gel, hexanes/DCM, 2: 1) and crystallization from methanol to give 4,7-bis(4-(tert-butyl)phenyl)-2-decyl-2H- benzo[i/][l,2,3]triazole (350 mg, 43% yield) as white crystals. ¾ NMR (400 MHz, CDC1 ₃ ): δ 7.99 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 7.60 (s, 2H, benzotriazole), 7.54 (d, J = 8.4 Hz, 4H, 4-t- BuC ₆ H ₄ ), 4.78 (t, J = 7.3 Hz, 2H, decyl), 2.15 (m, 2H, decyl), 1.38 (s, 18H, 2 t-Bu), 1.25 (m, 14H, decyl), 0.86 (t, J = 6.6 Hz, 3H, decyl). UV-vis spectrum (PVB film): _max = 345 nm. Fluorimetry (PVB film): _max = 416 nm

Example 2-9. 2-((3r.5r.7r)-adamantan-l-ylmethyl)-4.7-bis(4-(ter?-butyl)ph enyl)-2H- benzor<fUT .2.3 ^" |triazole.

Step 1. (3r,5rJr)-Adamantan-l-ylmethyl 4-methylbenzenesulfonate.

[0180] Triethylamine (11.2 mL, 80 mmol) was added in portion to a solution of (3r,5r,7r)-adamantan-l-ylmethanol (10.00 g, 60 mmol) and 4-toluenesulfonyl chloride (9.53 g, 50 mmol) in DCM (100 mL) cooled in an ice bath. The obtained mixture was stirred then at room temperature overnight followed by heating at 50 °C for 48 hours. The mixture was poured into ice/water (200 mL) and diluted with DCM (100 mL). The DCM layer was separated, dried over magnesium sulfate, and the volatiles were removed under reduced pressure. The residue was triturated with hexanes to give crystalline (3r,5r,7r)-adamantan-l- ylmethyl 4-methylbenzenesulfonate (10.14 g, 53% yield). ¾ NMR (400 MHz, CDC1 ₃ ): δ 7.76 (d, J = 8.4 Hz, 2H, 4-MeC ₆ H ₄ S0 ₂ ), 7.33 (d, J = 8.4 Hz, 2H, 4-MeC ₆ H ₄ S0 ₂ ), 3.54 (s, 2H,

0- CH ₂ ), 2.44 (s, 3H, 4-MeC ₆ H ₄ S0 ₂ ), 1.94 (m, 6H, adamantanyl), 1.66 (m, 6H, adamantanyl), 1.60 (m, 3H, adamantanyl).

Step 2. 2-((3r, 5r, 7r)-adamantan- 1 -ylmethyl)-4 J-bis(4-(fer/-butyl)phenyl)-2H- benzor<fUT ,2,3 ^" |triazole.

[0181] A mixture of intermediate 2-D (767 mg, 2.0 mmol), (3r,5r,7r)-adamantan-

1- ylmethyl 4-methylbenzenesulfonate (961 mg, 3.0 mmol), potassium carbonate (1.38 g, 10 mmol), and NMP (25 mL) was stirred under argon and heated at 150 °C for 48 hours. The reaction mixture was poured into water (300 mL) and stirred for 16 hours. The precipitate was filtered off, washed with water (100 mL), and dried in a vacuum oven. The crude product was purified by chromatography (silica gel, hexanes/DCM, 3 : 1) and recrystallization from acetone to give 2-((3r,5r, 7r)-adamantan-l-ylmethyl)-4,7-bis(4-(tert-butyl)phenyl)-2H- benzo[i/][l,2,3]triazole (556 mg, 52% yield) as colorless crystals. ^X H NMR (400 MHz, CDCI3): δ 8.01 (d, J = 8.4 Hz, 4H, 4-/-BuC ₆ H ₄ ), 7.61 (s, 2H, benzotriazole), 7.54 (d, J = 8.4 Hz, 4H, 4-/-BuC ₆ H ₄ ), 4.49 (s, 2H), 2.02 (m, 3H, adamantanyl), 1.69 (m, 12 H, adamantanyl), 1.38 (s, 18H, f-Bu). UV-vis spectrum (PVB film): _max = 348 nm. Fluorimetry (PVB film): λ = 416 ηηι.

Example 2-10. 4-(4 J-Bis(4-(ter/-butyl)phenyl)-2H-benzort/1 [1 ,2,31triazol-2-yl)butyl benzoate

[0182] A mixture of intermediate 2-E (570 mg, 0.82 mmol), sodium benzoate (720 mg, 15.0 mmol) and NMP (12 mL) was stirred under argon at 150 °C for 16 hours. Then it was poured into ice/water (200 mL) and extracted with ethyl acetate/toluene (2: 1, 2 x 200 mL). The extract was washed with water (100 mL), dried over magnesium sulfate, and the volatiles were removed under reduced pressure. Chromatography of the residue (silica gel, hexanes/DCM, 1 : 1) and recrystallization from methanol afforded 4-(4,7-bis(4-(tert- butyl)phenyl)-2H-benzo[i/][l,2,3]triazol-2-yl)butyl benzoate (254 mg, 55% yield) as white crystals. ^X H NMR (400 MHz, CDC1 ₃ ): δ 8.02 (m, 2H, Ph), 7.99 (d, J = 8.4 Hz, 4H, 4-t- BuC ₆ H ₄ ), 7.62 (s, 2H, benzotriazole), 7.54 (m, 1H, Ph), 7.53 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 7.40 (m, 2H, Ph), 4.88 (t, J = 7.0 Hz, 2H), 4.39 (t, J = 6.4 Hz, 2H), 2.35 (m, 2H), 1.89 (m, 2H), 1.38 (s, 18H, t-Bu). UV-vis spectrum (PVB film): _max = 347 nm. Fluorimetry (PVB film): _max = 416 nm.

Example 2-11. l-(4-(4-(4J-bis(4-(ter?-butyl)phenyl)-2H-benzo rL2,31triazol-2- yl)butoxy)phenyl)ethanone.

[0183] Starting from 4-hydroxyacetophenone, a procedure analogous to that described in Example 2-10 was applied to give l-(4-(4-(4,7-bis(4-(tert-butyl)phenyl)-2H- benzo[i/][l,2,3]triazol-2-yl)butoxy)phenyl)ethanone as white crystals. ¾ NMR (400 MHz, CDC1 ₃ ): δ 7.98 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 7.90 (d, J = 8.8 Hz, 2H, 4-acetophenoxy) 7.61 (s, 2H, benzotriazole), 7.53 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 6.89 (d, J = 8.8 Hz, 2H, 4- acetophenoxy), 4.88 (t, J = 7.0 Hz, 2H), 4.07 (t, J = 6.3 Hz, 2H), 2.53 (s, 3H, 4- acetophenoxy), 2.38 (m, 2H), 1.91 (m, 2H), 1.38 (s, 18H, f-Bu). UV-vis spectrum (PVB film): _max = 347 nm. Fluorimetry (PVB film): _max = All nm.

Example 2-12. 2-(4-(4J-Bis(4-(ter?-butyl)phenyl)-2H-benzort/irL2,31triazol -2- yl)butyl)isoindoline- 1 ,3-dione.

[0184] A mixture of intermediate 2-D (575 mg, 1.5 mmol), N-(4- bromobutyl)phthalimide (564 mg, 2.0 mmol) potassium carbonate (414 mg, 3.0 mmol), and ΝΜΡ (12 mL) was stirred under argon at 120 °C for 16 hours. Then, it was poured onto crushed ice (100 g). When the ice melted, the solid was filtered off and recrystallized from acetone to give 2-(4-(4,7-bis(4-(tert-butyl)phenyl)-2H-benzo[i/][l,2,3]triaz ol-2- yl)butyl)isoindoline-l,3-dione (855 mg, 97% yield) as white crystals. ^X H NMR (400 MHz, CDC1 ₃ ): δ 7.97 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 7.83 (m, 2H, phthalimide), 7.69 (m, 2H, phthalimide), 7.60 (s, 2H, benzotriazole), 7.52 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 4.83 (t, J = 7.2 Hz, 2H), 3.78 (t, J = 7.0 Hz, 2H), 2.19 (m, 2H), 1.81 (m, 2H), 1.38 (s, 18H, t- u). UV-vis spectrum (PVB film): m _ax = 346 nm. Fluorimetry (PVB film): _max = All nm.

[0185] The reaction was carried out in a similar fashion to that described in Example 2-12. The crude product was recrystallized from methanol to give 2-(5-(4,7-bis(4- (tert-butyl)phenyl)-2H-benzo[i/][l,2,3]triazol-2-yl)pentyl)i soindoline-l,3-dione in 74% yield as white crystals. ^X H NMR (400 MHz, CDC1 ₃ ): δ 7.96 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 7.81 (m, 2H, phthalimide), 7.68 (m, 2H, phthalimide), 7.60 (s, 2H, benzotriazole), 7.54 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 4.78 (t, J = 7.3 Hz, 2H), 3.70 (t, J = 7.2 Hz, 2H), 2.19 (m, 2H), 1.76 (m, 2H), 1.47 (m, 2H), 1.38 (s, 18H, f-Bu). UV-vis spectrum (PVB film): _max = 346 nm. Fluorimetry (PVB film): _max = 416 nm.

Example 2-14. Diethyl 2-(6-( ^' 4J-bis( ^' 4-( ^' ter?-butyl)phenyl)-2H-benzort/irL2,31triazol-2- yDhexyPmalonate.

[0186] A solution of diethyl malonate (351mg, 2.2 mmol) in anhydrous DMF (10 mL) was added dropwise to a mixture of 60% NaH (85 mg, 2.2 mmol) in anhydrous DMF (15 mL) over 10 min at RT under 2 atmosphere. The reaction was slightly exothermic. After the addition was completed, the resultant mixture was stirred at room temperature for 30 min and then a solution of intermediate C (1.00 g, 1.83 mmol) in anhydrous DMF (15 mL) was added. The obtained mixture was heated at 65 °C under nitrogen for 2 hours and then set aside at RT for 2 days. The mixture was poured into ice/water and extracted into ethyl acetate. The organic layer was separated, dried over magnesium sulfate, and concentrated to dryness. The crude product was purified by column chromatography (silica gel, hexanes/ethyl acetate, 9: 1) to give Diethyl 2-(6-(4,7-bis(4-(tert-butyl)phenyl)-2H-benzo[if|[ 1,2,3 ]triazol-2- yl)hexyl)malonate (0.93 g, 81% yield) as colorless liquid. ¾ NMR (400 MHz, CDC1 ₃ ) : δ 7.98 (d, J = 8.4Hz, 4H, 4-tert-BuC ₆ H ₄ ), 7.60 (s, 2H benzotriazole), 7.76 (d, J = 8.4 Hz, 4H, 4-tert-BuC ₆ H ₄ ), 4.76 (t, J = 7.3 Hz, 2H), 4.18 (m, 4H, Et), 3.29 (t, J = 7.7 Hz ,1H, malonate), 2.13 ( m, 2H), 1.88 ( m, 2H), 1.39 ( m, 4H), 1.38 (s, 18H), 1.36 (m ,4H), 1.23 (t, J = 7.1 Hz, 6H, Et). UV-vis spectrum (PVB film): _max = 345 nm. Fluorimetry (PVB film): _max = 416 nm.

-(4,7-bis(4-(tert-butyl)phenyl)-2H-benzo[d][l,2,3]triazol-2-

[0187] Potassium carbonate (506 mg, 3.7 mmol)) was added to a mixture of intermediate 2-C (1.00 g, 1.83 mmol), ethyl salicylate (365 mg, 2.2 mmol) and DMF (20 mL). The resultant mixture was stirred at 85 °C under Nitrogen atmosphere for 16 hours. The mixture was poured into ice/water (200 mL) and extracted with ethyl acetate. The extract was dried over magnesium sulfate, and the solvent was removed under reduced pressure. The crude product was purified by column chromatography (silica-gel, hexanes/ethyl acetate (4: 1) to give 2-((6-(4,7-bis(4-(tert-butyl)phenyl)-2H-benzo[i/][l,2,3]tria zol-2- yl)hexyl)oxy)benzoate (780 mg, yield 67%) as colorless gummy liquid H NMR (400 MHz, CDC1 ₃ ): δ 7.99 (d, J = 8.0 Hz, 4H), 7.75 (m, 1H), 7.61 (s, 2H), 7.54 (d, J = 8.0 Hz, 4H), 7.40 (m, 1H), 6.92 (m, 2H) 4.80 (t, J = 7.1 Hz ,2H), 4.32 (q, J = 6.7 Hz ,2H), 4.01 (t, J = 6.6 Hz, 2H), 2.20 (m, 2H), 1.84 (m, 2H), 1.64-1.44 (m, 4H), 1.38 (s, 18H), 1.32 (t, J = 7.1 Hz, 3H). UV-vis spectrum (PVB film): _max = 345 nm. Fluorimetry (PVB film): _max = 415 nm.

Example 2-16. 6-(4.7-bis(4-(ter?-butyl)phenyl)-2H-benzor(iiri.2.31triazol- 2-yl)hexyl 2- hydroxyacetate and 6-(4J-bis(4-(ter?-butyl)phenyl)-2H-benzor(i1 Γ 1 ,2,3 ^" |triazol-2-yl)hexan- 1- ol.

[0188] Potassium carbonate (506 mg, 3.7 mmol) was added to a mixture of intermediate 2-C (1.00 g, 1.83 mmol), glycolic acid (167 mg, 2.2 mmol) and DMF (20 mL). The resultant mixture was stirred at 85 °C under nitrogen for 16 hours. The mixture was poured into ice/water (200 mL) and extracted with ethyl acetate. The extract was dried over magnesium sulfate and concentrated under reduced pressure and subjected to column chromatography (silica-gel, hexanes/ethyl acetate (4: 1) to give 6-(4,7-bis(4-(/ert- butyl)phenyl)-2H-benzo[i/][l,2,3]triazol-2-yl)hexyl 2-hydroxyacetate (397 mg, 40% yield), colorless gummy liquid as the first fraction. ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.98 (d, J = 8.4Hz, 4H), 7.61 (s, 2H), 7.54 (d, J = 8.4 Hz, 4H), 4.17 (t, J = 3.6 Hz , 2H), 4.1 1 (d, J = 5.4 Hz, 2H), 2.19 (t, J = 5.4 Hz, 1H), 2.19-2.15 (m, 2H), 1.68-1.65 (m, 2H), 1.56-1.55 (m, 2H), 1.45-1.41 (m, 4H), 1.38 (s, 18H). ). UV-vis spectrum (PVB film): _max = 344 nm. Fluorimetry (PVB film): _max = 415 nm.

[0189] The second fraction from chromatography gave 6-(4,7-bis(4-(/er/- butyl)phenyl)-2H-benzo[i/][l,2,3]triazol-2-yl)hexan-l-ol (294 mg, 29% yield) as colorless crystals. ^X H NMR (400 MHz, CDC1 ₃ ) : δ 7.99 (d, J = 8.4Hz, 4H), 7.61 (s, 2H), 7.54 (d, J = 8.4 Hz, 4H), 4.79 (t, J = 3.6 Hz, 2H), 3.65 (q, J = 3.6 Hz, 2H), 2.19-2.15 (m, 2H), 1.59-1.54 (m, 3H), 1.45-1.25 (m, 4H), 1.38 (s, 18H). UV-vis spectrum (PVB film): _max = 344 nm. Fluorimetry (PVB film): _max = 415 nm.

Example 2-17. 3-(4.7-bis(4-(ter?-butyl)phenyl)-2H-benzort/iri.2.31triazol- 2-yl)-N.N- dimethylpropanamide.

[0190] A mixture of intermediate 2-D (384 mg, 1.0 mmol) and Ν,Ν- dimethylacrylamide (1.00 g, 9.7 mmol) was heated under argon at 90 °C for 24 hours. TLC indicated no intermediate 2-D left. The crude product was purified by column chromatography (silica gel, hexanes/ethyl acetate (1 : 1) and recrystallization from acetone to give 3-(4,7-bis(4-(tert-butyl)phenyl)-2H-benzo[if|[l,2,3]triazol- 2-yl)-N,N- dimethylpropanamide (250 mg, 52% yield). ^X H NMR (400 MHz, CDC1 ₃ ): δ 7.99 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 7.61 (s, 2H, benzotriazole), 7.54 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 5.15 (t, J = 7.7 Hz, 2H, CH ₂ ), 3.19 (t, J = 7.5 Hz, 2H, CH ₂ ), 2.99 (s, 3H, Me-N), 2.98 (s, 3H, Me- N), 1.38 (s, 18H, 2 t-Bu). UV-vis spectrum (PVB film): _max = 346 nm. Fluorimetry (PVB film): _max = 418 nm.

[0191] A mixture of intermediate 2-F (purity 80%, 862 mg, 1.0 mmol), sodium acetate (820 mg, 10.0 mmol) and NMP (10 mL) was stirred under argon and heated at 100 °C for 24 hours. The reaction mixture was poured into water (200 mL) and stirred for 30 min. The precipitate was filtered off, washed with water (50 mL) and dried in a vacuum oven. The obtained crude product was purified by column chromatography (silica gel, hexanes/ethyl acetate, 4: 1) and recrystallization from methanol to give (2-acetoxy-l-((4,7-bis(4-(tert- butyl)phenyl)-2H-benzo[i/][l,2,3]triazol-2-yl)methyl)cyclopr opyl)methyl acetate (260 mg, 46% yield) as white crystals. ^X H NMR (400 MHz, CDC1 ₃ ): δ 7.96 (d, J = 8.4 Hz, 4H, 4-t- BuC ₆ H ₄ ), 7.61 (s, 2H, benzotriazole), 7.53 (d, J = 8.4 Hz, 4H, 4-?-BuC ₆ H ₄ ), 4.55 (dd, J = 8.1 and 4.8 Hz, 1H, cyclopropane), 4.38 (d, J = 11.8 Hz, 1H, BtCH ₂ ), 4.17 (d, J = 12.5 Hz, 1H, AcOCH ₂ ), 4.15 (d, J = 1 1.8 Hz, 1H, BtCH ₂ ), 4.03 (d, J = 12.5 Hz, 1H, AcOCH ₂ ), 2.31 (m, 1H, cyclopropane), 2.13 (s, 3H, Ac), 1.81 (s, 3H, Ac), 1.63 (t, J = 7.5 Hz, 1H, cyclopropane), 1.38 (s, 18H, t- u); ¹³ C NMR (CDC1 ₃ ): δ 15.5, 20.6, 21.0, 27.7, 31.4, 45.5, 62.6, 65.4, 125.0, 125.7, 128.2, 129.8, 143.6, 151.1, 170.5, 171.0. UV-vis spectrum (PVB film): _max = 349 nm. Fluorimetry (PVB film): _max = 422 nm.

Method for preparing fluorescent composite particles

[0192] The fluorescent composite particles comprising silica as the inorganic oxide matrix were prepared as follows: 1) Disperse a chromophore Compound 1 into ethanol at a wt. ratio of 1 to 100 to obtain a chromophore solution. 2) Place the chromophore solution in an ultrasonicator for 30 min or more to provide even dispersing of the chromophore particles in the solution, and then further stir the chromophore solution for at least 30 min. 3) Add tetraethoxysilane (TEOS) and isopropanol (IP A) into a round bottom flask at a wt. ratio of about 1 to about 10-50 and stir at room temperature for about 5-10 min. The mole ratio of chromophore to TEOS is about 1 : 4-20. 4) Pour the obtained chromophore solution gradually into the flask and continuously stir the mixture to obtain a homogenous dispersion. 5) Add a trace amount of diethanolamine as a catalyst into the mixture and stir at room temperature for at least 30 min, and then further simultaneously stir and heat the mixture at about 60-100 °C for about 30-60 min for gelation. 6) Cool the mixture to obtain precipitates and separate the precipitates by filtration. 7) Wash the filtrate by ethanol or water to remove the solvent and catalyst completely. 8) Vacuum dry the filtrate at about 100-120 °C for 1-2 hours to obtain a solid powder of the fluorescent composite particles.

Optically Transparent Polymer Matrix

[0193] Ethylene vinyl acetate copolymer (EVA) was obtained from DuPont (DuPont Elvax product PV1400Z) or Arkema and used as received. In some embodiments, the vinyl acetate content in the EVA is in the range of 20 to 45 parts by weight, and preferably in the range of 28 to 33 parts by weight, based on 100 parts by weight of EVA. For the Example Compositions 1- 2 below, the vinyl acetate content in the EVA is 32 parts by weight, based on 100 parts by weight of EVA.

[0194] Ethylene methyl methacrylate copolymer (EMMA) was obtained from Sumitomo Chemicals (Acryft WK307) used as received. In some embodiments, the methyl methacrylate (MMA) content in the EMMA is in the range of 5 to 32 parts by weight, and preferably in the range of 10 to 25 parts by weight, based on 100 parts by weight of EMMA.

Adhesion promoter

[0195] As the adhesion promoter, a silane coupling agent 3- methacryloxypropyltrimethoxysilane (KBM-503) was obtained from ShinEtsu and used as received.

Stabilizer

[0196] The stabilizer Bis(l,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(l, l- dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate (Tinuvin 144) was obtained from BASF and used as received.

UV absorber

[0197] The UV absorbers 2-Hydroxy-4-(octyloxy)benzophenone (Chimassorb 81) and 2,2'-Methylenebis [6-(2H-benzotriazol-2-yl)-4-( 1, 1,3,3 -tetramethylbutyl)phenol] Tinuvin 360 were obtained from BASF and used as received.

Crosslinking Coagent

[0198] The crosslinking coagents trimethylolpropane trimethylmethacrylate (TMPTMA) was purchased from Aldrich and used as received.

Crosslinking Agent

[0199] The organic peroxides t-butylperoxy-2ethylhexylmonocarbonate (Perbutyl E), was used as a crosslinking agents, and was obtained from NOF Co. and used as received. [0200] The following examples, are for illustrative purposes only and are not intended to limit any particular embodiment.

Example 1 - Preparation of Wavelength Conversion Layer

[0201] A wavelength conversion composition testing sample was prepared. The components of the composition were as follows:

[0202] To prepare the composition, a wavelength conversion layer comprising the components listed above was fabricated into a film structure following the wet processing procedure. The wavelength conversion layer is fabricated by (i) preparing a polymer solution by dissolving the EVA or EMMA polymer powder or pellets in a soluble solvent such as toluene, at a predetermined ratio; (ii) preparing a fluorescent composite particle dispersion by dispersing the fluorescent composite particles in the same solvent as the polymer solution at the predetermined concentration; (iii) preparing a stabilizer solution by dissolving a stabilizer in the same solvent as the polymer solution at the predetermined concentration; (iv) preparing a UV absorber solution by dissolving a stabilizer in the same solvent as the polymer solution at the predetermined concentration; (v) preparing a wavelength conversion (WLC) solution by mixing the polymer solution with the chromophore solution and the stabilizer solution, and then adding the adhesion promoter, the coagent(s), and the peroxide (crosslinking agent), independently and at the predetermined weight ratio; and (vi) forming the wavelength conversion layer by directly casting the wavelength conversion solution onto a non-stick PTFE dish, then drying the WLC solution at room temperature for at least 24 hours and further drying the mixture under vacuum at 50-60 °C for 4-6 hours, completely removing the remaining solvent by further vacuum hot pressing at 80-100 °C for 10 min to a thickness of 300μιη. The wavelength conversion film was then laminated between two pieces of clear low-iron glass that were 2 mm thick and approximately 5 cm x 5 cm in dimension. Following lamination, the testing device was then cured to induce crosslinking. The curing temperature for the Example 1 testing device was 160 °C with a curing time of 15 minutes.

Measurement of the photostability

[0203] An indoor Weatherometer chamber model Suntest XXL+ from Atlas, was used to provide accelerated radiation aging of the test samples. The weatherometer conditions were as follows: UV exposure of 60W/m ² at 65 °C and 60% relative humidity. For each testing sample, the absorption of the film was measured and used to determine the degradation of the chromophore within the layer. The absorption of the wavelength conversion films were measured using a UV-Vis-NIR Spectrophotometer model UV-3600 from Shimadzu. For each example composition, the absorption was measured after various irradiation exposure times in the Suntest chamber, and the normalized absorption was calculated to determine the photostability of the composition.

[0204] Table 1 shows the normalized absorption of the Example 1 testing device after various exposure times.

Comparative Example 2

[0205] A Comparative Example 2 testing sample is synthesized using the same method as given in Example 1, except the chromophore was not embedded into an inorganic matrix. The wavelength conversion composition was as follows:

[0206] Table 1 shows the normalized absorption of the Comparative Example testing device after various exposure times.

Example 3

[0207] An Example 3 testing sample is synthesized using the same method given in Example 1. The wavelength conversion composition was as follows:

[0208] Table 1 shows the normalized absorption of the Example 3 testing device after various exposure times.

Comparative Example 4

[0209] A Comparative Example 4 testing sample is synthesized using the same method as given in Example 1, except the chromophore was not embedded into an inorganic matrix. The wavelength conversion composition was as follows:

Component Concentration (parts by weight)

(vi) Tinuvin 360 0.2

(vi) Perbutyl E 0.1

Example 5

[0210] An Example 5 testing sample is synthesized using the same method as given in Example 1, except that Chromophore 3 was used in the fluorescent composite particles. The wavelength conversion composition was as follows:

[0211] Table 1 shows the normalized absorption of the Example 5 testing device after various exposure times.

Comparative Example 6

[0212] A Comparative Example 6 testing sample is synthesized using the same method as given in Example 5, except the chromophore was not embedded into an inorganic matrix. The wavelength conversion composition was as follows:

Component Concentration (parts by weight)

(i) EVA: 100

(ii) Chromophore 3 0.1

(iii) KBM-503 0.1

(iv) Tinuvin 144 0.1

(v) TMPTMA 5 Component Concentration (parts by weight)

(vi) Tinuvin 360 0

(vi) Perbutyl E 0.3

[0213] Table 1 shows the normalized absorption of the Comparative Example 6 testing device after various exposure times.

Table 1 Normalized absorption after various exposure time for the Example devices.

[0214] One object of some embodiments is to provide a wavelength conversion film that is useful to enhance efficiency of solar energy conversion devices. As illustrated by the above examples, the film is very stable after exposure to solar radiation for long periods of time. Therefore, the application of this film to the photovoltaic or agriculture industry may be useful.