AND USES THEREOF

Priority Claims and Related Patent Applications

[0001] This application claims the benefit of priority from U.S. Provisional Application Serial No. 62/269,197, filed on December 18, 201S, the entire content of which is incorporated herein by reference in its entirety.

Technical Fields of the Invention

[0002] The invention generally relates to semiconductor nanocrystals and their applications. More particularly, the invention relates to novel methods for manufacturing nanocrystals of semiconductor materials to afford high-quality quantum dots. Methods of the invention utilize low-cost precursor materials and mild, environmentally friendly processes and are readily suitable for large-scale commercial production.

Background of the Invention

[0003] Quantum dots are nanocrystals of a semiconducting material with diameters on the order of several nanometers. Quantum dot-based nano -materials have become an important class of materials finding diverse applications ranging from consumer electronics to medical products. Quantum dots, first discovered in the 1980s, have the size comparable or on the same order of the exciton Bohr radius, leading to the excitons experiencing a phenomenon called "quantum confinement". Quantum dots exhibit exceptional electronic properties that are between those of bulk semiconductors and discrete molecules. Properties such as the band gap, emission color, and absorption spectrum may be fine-tuned by controlling the size distribution of quantum dots during fabrication.

[0004] Quantum dots have been studied for applications in a variety of fields, for example, in electronics, optics, solar photovoltaics, processing techniques and inkjet printing. Their unique optical properties, broad range excitation and tunable emission spectra have lead to the emergence of a new class of fluorescent probes for molecular, cellular and in vivo medical imaging and diagnostics. (Reed, et al. 1988 Phys Rev Lett 60(6): 535-537; Bruchez, et al. 1998 Science 281: 2013-2016; Wu, et al.2003 Nat. Biotechnol.21: 41-46; Murray, et al.2000 Annual Rev. Mat. Res. 30(1): 545-610; Coe-Sullivan, et al.2005 Adv. Functional Mat. 15(7): 1117— 1124.)

[0005] Major challenges remain in expanding applications for quantum dots. Quantum dots offering very narrow full width at half maximum (FWHM) and high quantum yield have not been achieved by current traditional phosphors (e.g., YGA). Such quantum dots are highly desirable in display technologies. Fabrication methods of high-quality quantum dots on commercial scale continue to present significant challenges.

[0006] Commercial production of quantum dots currently relies on a high temperature dual injection (or "hot injection") process. The process typically involves high temperature and delicate control of dual or multiple injection systems. Quality and reproducibility remain challenging with the hot-injection methodology.

[0007] Other rapid-injection techniques, such as disclosed in US. Patent Nos. 8,354,090, 8,658,439 and 9,139,435, are not suited for large-scale commercial production due to the complexity of rapid-injection system set-up, precursors used, reaction conditions and environmental impact. U.S. Patent No. 8,354,090, for example, involves the use of a plurality of precursor micro streams diverged and rejoined at controlled times and temperatures. The achieved FWHM and quantum yields leave much room for improvement

[0008] Thus, an ongoing need exists for novel technologies that preparation of high-quality quantum dots from low-cost precursor materials under reliable, mild, environmentally friendly conditions suitable for large-scale commercial production.

Summary of the Invention

[0009] The invention is based in part on the discovery of a unique approach to preparation of high-quality quantum dots. The methods disclosed herein utilize low-cost precursor materials. The reaction conditions are reliable, milder, more environmentally friendly than existing technologies. Furthermore, the methods of the present invention are suitable for and can be readily adapted to large-scale commercial production.

[0010] The methods of the invention enable production of QDs with comparable or superior FWHM but under much more relaxed reaction conditions. It is well known that stable and high quantum efficient green quantum dots are always hard to synthesize. Green quantum dots produced according to the present invention exhibit superior optical properties compared to other types of green quantum dots (e.g., InP, CIS and CdSe) with much narrower FWHM (22 nm) and very high quantum yield (at least 90%).

[0011] Quantum dots offering very narrow FWHM (e.g., < 30 nm) and high quantum yield (e.g., > 80%) are highly desirable in display technologies. With next generation ultra high definition TV (UHDTV) on the horizon, quantum dot technology provides high performance and energy efficiency at low cost and can be easily incorporated into the current display manufacture process, while other technologies suffer from several setbacks: high cost (OLED, Laser and RGB LED), high energy consumption (OLED and RGB LED), and/or manufacture incorporation complexity (OLED).

[0012] Currently, most quantum dot manufacture methods rely on rapid precursor injection to achieve quantum dot uniformity. The injection step inevitably increases syntheses complexity and poses significant challenge for scale-up needed for commercialization.

[0013] The non-injection synthetic approach couple with the mild reaction conditions, as first disclosed herein, allow for significantly reduction in the cost of mass production. By carefully adjusting the chemical properties of the precursors, the one-pot, heat-up synthetic approach disclosed herein enables one to achieve the comparable or superior quality with much less complexity in terms of equipment needs, condition controls and precursor sourcing, and much reduced lead (II) precursor input (nearly 80% less). The product yield is also much better than those reported in literature. Overall, the disclosed method is ideally suited for large-scale manufacture of quantum dots at low cost and environmental impact.

[0014] In one aspect, the invention generally relates to a method for making quantum dots. The method includes: providing in an organic solvent a solution comprising a cesium precursor, a lead (II) precursor, a halide precursor, and in some preparations suitable coordination ligands, wherein the molar ratio of cesium: lead (II) is from about 1 : 10 to about 10 : 1; heating the solution to a temperature from about 0 °C to about 350 °C under an inert atmosphere and maintaining at the temperature for about 1 second to about 1 day to afford quantum dots in the solution; and cooling the solution to room temperature (e.g., by ice bath, water or dry ice bath) to isolate the quantum dots. [0015] In another aspect, the invention generally relates to a method for making semiconductor nanocrystals and provides an improved and much more efficient and effective injection-based synthesis of quantum dots. The method includes: providing in an organic solvent a solution comprising a cesium precursor, a lead (II) precursor, a halide precursor, and in some preparations suitable coordination ligands, wherein the molar ratio of cesium: lead (II) is from about 1 : 10 to about 10:1; heating the solution to a temperature from about 0 °C to about 350 °C under an inert atmosphere; swiftly injecting a halide precursor into the solution; maintaining the solution at the temperature for about 0.1 second to about 1 day to afford quantum dots in the solution; and cooling the solution to room temperature {e.g., by ice bath, water or dry ice bath) to isolate the quantum dots.

[0016] In another aspect, the invention generally relates to a method for making semiconductor nanocrystals. The method includes: providing in an organic solvent a solution comprising a halide precursor, and in some preparations suitable coordination ligands; heating the solution to a temperature from about 0 °C to about 350 °C under an inert atmosphere; swiftly injecting a solution comprising an organic solvent, cesium and lead (II) precursor into the halide precursor solution, wherein the molar ratio of cesium: lead (II) is from about 1 : 10 to about 10 : 1;

maintaining the solution at the temperature for about 0.1 second to about 1 day to afford quantum dots in the solution; and

cooling the solution to room temperature (e.g., by ice bath, water or dry ice bath) to isolate the quantum dots.

[0017] In yet another aspect, the invention relates to quantum dot materials prepared by a synthetic method disclosed herein.

[0018] In yet another aspect, the invention relates to a device or component thereof (e.g. , an optoelectronic device or component thereof, a photovoltaic device or a component thereof, or a medical imaging or diagnostic probe or agent) that includes a quantum dot material prepared by a synthetic method disclosed herein.

Brief Description of the Drawings

[0019] FIG. 1 shows exemplary emission spectral data of quantum dots prepared according to certain embodiments of the invention. Detailed Description of the Invention

[0020] The invention provides a novel approach to preparation of high-quality quantum dots. The methods disclosed herein utilize low-cost precursor materials, employs mild reaction conditions, and are environmentally friendly than existing technologies. Importantly, the methods of the present invention can be readily adapted to reliable, large-scale commercial production.

[0021] The CsPbX3 (X = CI, Br, I) QDs prepared according to the present invention have comparable or superior FWHM. For example, the green CsPbBis quantum dots exhibit superior optical properties compared to other types of green quantum dots (e.g., InP, CIS and CdSe) with much narrower FWHM (22 nm) and very high quantum yield (at least 90%).

[0022] The nano crystal formation mechanisms are different between method of the present invention and the reported methods. In the synthesis of CsPbBr3, for example, lead (II) oleate is used instead of lead bromide. Using lead oleate and benzyl bromide (or other lead and bromide compounds) helps to control the crystal formation process. The reported methods use lead bromide, leading to a fast reaction and a precipitation nanocrystal formation process that is hard to control. By using lead (II) oleate as the lead (II) source and benzyl bromide as the bromide source, the reaction becomes an easily controlled colloid nanocrystal formation process. Besides being modifiable to produce the desired QDs by allowing wide range of selection for reaction time and temperature to impact crystal quality, the process is also easily scalable.

[0023] A significant improvement over the reported methods is that the method of the invention is characterized by much efficient use of lead (II) ( Pb ² *). In certain embodiments of the invention for the synthesis of CsPbX3 (X = CI, Br, I) quantum dot product, the molar ratio of Cs : Pb precursors is around 1 : 1. The reported methods need substantially more lead (II) precursor with the molar ratio of Cs : Pb precursors typically around 1 : 4-5, where a large amount of the lead (II) precursor does not react (almost 80%). This leaves large quantities of lead waste, both economically and environmentally undesirable.

[0024] Another significant improvement over the literature methods is that homogenous mixing of the precursor reagents can be easily achieved with the heat-up method disclosed herein, which helps with both the yield and quality of the QDs allows (e.g., improved

monodispersity). [0025] A further significant improvement over the literature methods is that the precursors used in the present invention (e.g., cesium oleate, lead (II) oleate and benzyl halide) all fully dissolve in ODE under 100 °C even without surfactants. The favorable solubility of the precursors allows for much milder and flexible preparation conditions. Lead (II) bromide, which is used in the literature as the lead (II) and bromine source, requires surfactants (e.g., oleic acid and oleylamine) and much elevated temperature (e.g., 140 °C) to help it dissolve.

[0026] It is important to adjust the reactivity of cesium compound and lead (II) compound since they are not totally free ions in organic solvent and will have different affinity to bromide compound. Their counter ions (e.g., carboxylate ion) can affect the ion exchange with bromide ion. By changing the counter ions of cesium and lead (II) compounds, their affinity to bromide ion can be adjusted to be the same (or close to be the same) so that nanocrystals with correct ion composition could form. Accordingly, the method of the present invention allows other bromide compounds to be used as bromine source to adjust the precursor reactivity and the nanocrystal growth kinetics.

[0027] QDs prepared by the method of the present invention are high quality QDs as demonstrated by exemplary performance data shown in Table 1 and FIG. 1. FIG. 1 shows emission spectra of CsPbCb (blue), CsPbBrs (green), CsPbBrijIi.s (yellow) and CsPbb (red) quantum dots.

One-pot, heat-up Synthesis of Quantum Dots

[0028] In one aspect, the invention generally relates to a method for making quantum dots. The method includes: providing in an organic solvent a solution comprising a cesium precursor, a lead (II) precursor, a halide precursor, and optionally one or more coordination ligands that help to stabilize nanocrystals, wherein the molar ratio of cesium: lead (II) is from about 1 : 10 to about 10 :1; heating the solution to a temperature from about 0 °C to about 350 °C under an inert atmosphere and maintaining at the temperature for about 0.1 second to about 1 day to afford quantum dots in the solution; and cooling the solution to room temperature (by ice bath, water or liquid nitrogen) to isolate the quantum dots.

[0029] Cesium compounds and lead compounds of mild affinity to halogen are preferred. In certain embodiments, the cesium precursor is cesium oleate and the lead (II) precursor is lead (II) oleate. In certain other embodiments, the cesium precursor is cesium stearate and the lead (II) precursor is lead (II) stearate. Specific examples of suitable cesium compounds include cesium acetate, cesium undecylenate, cesium myristate, cesium laurate, cesium oleate, cesium palmitate, or combinations thereof. Specific examples of suitable lead (II) compounds include lead (II) acetate, lead (II) undecylenate, lead (II) myristate, lead (II) laurate, cesium oleate, lead (II) palmitate, or combinations thereof.

[0030] It is generally preferred that the molar amount of the lead (II) precursor is close to that of the cesium precursor. In certain embodiments, the molar ratio of cesium : lead (II) is from about 10 : 1 to about 1 : 10 (e.g., from about 5 : 1 to about 1 : 5, from about 1 : 2 to about 2 : 1, from about 0.8 : 1 to about 1 : 0.8, from about 0.9S : 1 to about 1 : 0.95, from about 0.99 : 1 to about 1 : 0.99).

[0031] Halide precursors of good reactivity are preferred. In certain embodiments, the halide precursors are selected from benzyl halide, tertiary-butyl halide, acetyl halide, ethyl halide, hydrogen halide, allyl halide, l-halo-4-nitrobenzene, n-dodecyl halide, n-octadecyl halide, iso- propyl halide, or combinations thereof.

[0032] Any suitable molar ratios of cesium : halide and lead (II) : halide may be employed. In certain embodiments, the molar ratio of (0.5*cesium + lead (II)) ·' halide is from about 10 : 1 to about 1 : 100 (e.g., from about 5 : 1 to about 1 : 50, from about 1 : 1 to about 1 : 20, from about 1 : 2 to about 1 : 10, from about 1 : 2.5 to about 1 : 5, from about 1 : 3 to about 1 : 4).

[0033] Depending on the desired product, the halide may comprise a chloride, a bromide, an iodide, or a combination of two or more thereof. In certain embodiments, the halide is a chloride. In certain embodiments, the halide comprises a bromide. In certain embodiments, the halide is an iodide. In certain embodiments, the halide comprises two of a chloride, a bromide and an iodide. In certain embodiments, the halide comprises two or three of a chloride, a bromide and an iodide. The molar ratio of CI to Br to I may be any suitable ratios depending on the desired quantum dots to be prepared.

[0034] Any suitable organic solvents may be used, for example, selected from 1 -decene, 1 - dodecene, 1-tetradecene, 1-hexadecene 1-octadecene, octadecane, benzene, trioctylphosphine, trioctylphospbine oxide and diphenyl ether.

[0035] Any suitable ligand (not essential in some preparation but may be utilized to control or fine-tune the quality of the quantum dots) may be used, for example, selected from oleic acid, myristic acid, palmitic acid, stearic acid, phenylphosphonic acid, hexylphosphonic acid, tetradecylphosphonic acid, oleylamine, octylamine, dioctylamine, trioctylamine, didodecylamine, tridodecylamine, hexadecylamine, dioctadecylamine, trioctadecylamine, or combinations of thereof. Selective use of suitable ligands can help with controlling broadening of particle size distribution due to Oswald ripening and/or particle aggregation. The ligands also serve to passiVate nanocrystal surface and reduce surface trap.

[0036] The temperature to which the solution is heated is generally chosen from about 0 °C to about 350 °C (e.g., from about 0°C to about 300 °C, from about 50 °C to about 275 °C, from about 90 °C to about 250 °C, from about 100 °C to about 200 °C, from about 100 °C to about 150 °C, from about 110 °C to about 140 °C, from about 120 °C to about 130 °C).

[0037] The amount of time at which the heated solution is maintained at the desired

temperature is generally chosen from about 0.1 second to about 1 day (e.g., from about 0.1 sec. to about 12 nr., from about 5 sec. to about 6 nr., from about 10 sec. to about 1 nr., from about 1 min. to about 30 min., from about 1 min. to about 15 min., from about 1 min. to about 10 min., from about 1 min. to about 5 min., from about 5 min. to about 10 min., from about 1 sec. to about 2 hr., from about 1 sec. to about 1 min., from about 1 sec. to about 30 sec., from about 1 sec. to about 10 sec, from about 15 sec. to about 5 min.).

[0038] Cooling of the reacted solution may be achieved by any suitable techniques, for example, by an ice bath, by water, by dry ice bath, or by liquid nitrogen. Typically the objective is to cool the solution to room temperature, although in certain embodiments, the solution may be cooled to slight below or above room temperature follow by workup procedures to isolate and/or purify the produced quantum dots.

[0039] In yet another aspect, the invention relates to quantum dot materials prepared by the one-pot, heat-up synthetic method disclosed herein. [0040] In yet another aspect, the invention relates to a device or component thereof that includes a quantum dot material prepared by the one-pot, heat-up synthetic method disclosed herein.

Heat-up / Im'ection-hvbrid Synthesis of (Quantum Dots

[0041] In another aspect, the invention generally relates to a method for making semiconductor nanocrystals and provides an improved and much more efficient and effective injection-based synthesis of quantum dots. The method includes: providing in an organic solvent a solution comprising a cesium precursor, a lead (II) precursor, in some cases suitable ligand(s), wherein the molar ratio of cesium: lead (II) is from about 1 : 10 to about 10 : 1; heating the solution to a temperature from about 0 °C to about 350 °C under an inert atmosphere; swiftly injecting a halide precursor into the solution; maintaining the solution at the temperature for about 0.1 second to about 1 day to afford quantum dots in the solution; and cooling the solution to room temperature to isolate the quantum dots.

[0042] In certain embodiments, the direction of injection can be reversed: providing in an organic solvent a solution comprising a halide precursor, and in some cases suitable ligand(s); heating the solution to a temperature from about 0 °C to about 350 °C under an inert atmosphere; swiftly injecting a solution comprising an organic solvent, cesium and lead (II) precursor into the halide precursor solution, wherein the molar ratio of cesium: lead (II) is from about 1 : 10 to about 10 : 1; maintaining the solution at the temperature for about 0.1 second to about 1 day to afford quantum dots in the solution; and cooling the solution to room temperature to isolate the quantum dots.

[0043] Cesium compounds and lead (Π) compounds of mild reactivity are preferred. In certain embodiments, the cesium precursor is cesium oleate and the lead (II) precursor is lead (II) oleate. In certain other embodiments, the cesium precursor is cesium stearate and the lead (II) precursor is lead (II) stearate. Specific examples of suitable cesium compounds include cesium acetate, cesium undecylenate, cesium myristate, cesium laurate, cesium oleate, cesium palmitate, or combinations thereof. Specific examples of suitable lead (II) compounds include lead (II) acetate, lead (II) undecylenate, lead (Π) myristate, lead (II) laurate, cesium oleate, lead (II) palmitate, or combinations thereof. [0044] It is generally preferred that the molar amount of the lead (II) precursor is close to that of the cesium precursor. In certain embodiments, the niolar ratio of cesium : lead (II) is from about 10 : 1 to about 1 : 10 (e.g., from about 5 : 1 to about 1 : S, from about 1 : 2 to about 2 : 1, from about 0.8 : 1 to about 1 : 0.8, from about 0.9S : 1 to about 1 : 0.95, from about 0.99 : 1 to about 1 : 0.99).

[004S] Halide precursors of good reactivity are preferred. In certain embodiments, the halide precursor is selected from, benzyl halide, tertiary-butyl halide, acetyl halide, ethyl halide, hydrogen halide, allyl halide, l-halo-4-nitrobenzene, n-dodecyl halide, n-octadecyl halide, iso- propyl halide, or combinations thereof.

[0046] Any suitable molar ratios of cesium : halide and lead (II) : halide may be employed. In certain embodiments, the molar ratio of (0.5*cesium + lead (II)) : halide is from about 10 : 1 to about 1 : 100 (e.g., from about 5 : 1 to about 1 : 50, from about 1 : 1 to about 1 : 20, from about 1 : 2 to about 1 : 10, from about 1 : 2.5 to about 1 : 5, or from about 1 : 3 to about 1 : 4).

[0047] Depending on the desired product, the halide may comprise a chloride, a bromide, an iodide, or a combination of two or three thereof. In certain embodiments, the halide is a chloride. In certain embodiments, the halide comprises a bromide. In certain embodiments, the halide comprises an iodide. In certain embodiments, the halide comprises two or three of a chloride, a bromide or an iodide. The molar ratio of CI to Br to I may be any suitable ratios depending on the desired quantum dots to be prepared.

[0048] Any suitable organic solvents may be used, for example, selected from octadecene, 1- decene, 1-dodecene, 1-tetradecene, 1-hexadecene 1 -octadecene, benzene, trioctylphosphine, trioctylphosphine oxide and diphenyl ether.

[0049] Any suitable ligand (optional in certain preparations) may be used, for example, selected from oleic acid, myristic acid, palmitic acid, stearic acid, phenylphosphonic acid, hexylphosphonic acid, tetradecylphosphonic acid, oleylamine, octylamine, &octylamine, trioctylamine, didddecylamine, tridodecylamine, hexadecylamine,

dioctadecylamine,trioctadecylamine, or combinations thereof.

[0050] The temperature to which the solution is heated is generally chosen from about 0 °C to about 350 °C (e.g., from about 0°C to about 300 °C, from about 20 °C to about 275 °C, from about 20 °C to about 250 °C, from about 20 °C to about 200 °C, from about 20 °C to about 150 °C, from about 20 °C to about 140 °C, from about 20 °C to aboutl30 °C, from about 20 °C to about 120 °C, from about 10 °C to about 110 °C, from about 30 °C to about 250 °C, from about 40 °C to about 200 °C, from about 50 °C to about 150 °C, from about 60 °C to about 140 °C, from about 70 °C to aboutl30 °C, from about 80 °C to about 120 °C and from about 90 °C to about 110 °C).

[0051] The amount of time at which the heated solution is maintained after the precursor injection at the desired temperature is generally chosen from about 0.1 second to about 1 day (e.g., from about 3 sec. to about 12 hr,, from about 5 sec. to about 6 hr., from about 10 sec. to about 1 hr., from about 1 min. to about 30 min., from about 1 min. to about 15 min., from about 1 min. to about 10 min., from about 1 min. to about 5 min., from about 5 min. to about 10 min., from about 1 sec. to about 2 hr., from about 1 sec. to about 1 min., from about 1 sec. to about 30 sec., from about 1 sec. to about 10 sec., from about 15 sec. to about 5 min.).

[0052] Cooling of the reacted solution may be achieved by any suitable techniques, for example, by an ice bath, water, dry ice or liquid nitrogen. Typically the objective is to cool the solution to room temperature, although in certain embodiments, the solution may be cooled to slight below or above room temperature follow by workup procedures to isolate and/or purify the produced quantum dots.

[0053] In yet another aspect, the invention relates to quantum dot materials prepared by the hybrid heat-up / injection synthetic method disclosed herein.

[0054] In yet another aspect, the invention relates to a device or component thereof that includes a quantum dot material prepared by the hybrid heat-up / injection synthetic method disclosed herein.

[0055] In certain embodiments, the CsPbX3 (X = Cl, Br, I) quantum dot materials prepared according to the present invention are characterized by a FWHM less than about 30 nm {e.g., less than about 25 nm).

[0056] In certain embodiments, the quantum dot materials prepared according to the present invention are characterized by a quantum yield of at least about 50 % (e.g., greater than about 60 %, greater than about 70 %, greater man about 80 %, greater than about 90 %). .

[0057] In certain embodiments, the invention relates to an optoelectronic device or a .

component thereof comprising a quantum dot material prepared according to methods disclosed herein. In certain embodiments, the invention relates to a photovoltaic device or a component thereof comprising a quantum dot material prepared according to methods disclosed herein. In certain embodiments, the invention relates to a medical imaging or diagnostic probe or agent comprising a quantum dot material prepared according to methods disclosed herein.

Examples

[0058] The following are non-limiting examples.

Exemplary Syntheses Procedure: One-pot. Heat-up Synthesis

[0059] 10 mL octadecene, 1 mL oleic acid, 1 mmol cesium oleate, 1 mmol lead (II) oleate and 4 mmol benzyl bromide (or other bromide reagent) were added to a reaction flask. The flask was degassed for 30 min. under room temperature then for 30 min. at 100 °C. Back filled the flask with nitrogen or argon. Then the solution was heated to 140 °C. The solution was kept at 140 °C for 1 min. Then, the solution was cooled to room temperature.

Exemplary Syntheses Procedure: Heat-up / Iniection-Hvbrid Synthesis

[0060] 10 mL octadecene, , 1 mL oleylamine, 1 mmol cesium oleate and 1 mmol lead (II) oleate were added to a reaction flask. Start the magnetic stir. The flask was degassed for 30 min. under room temperature then for 30 min. at 100 °C. Back filled the flask with nitrogen or other inert gas (e.g., argon). Then the solution was heated to 120 °C). Benzyl bromide (4 mmol, or other bromide reagent) was quickly injected into the reaction flask. The solution was kept at 120 °C for 2 min. Then, the solution was cooled to room temperature.

Exemplary Syntheses Procedure: Heat-up / Iniection-Hvbrid Synthesis (reverse injection)

Exemplary synthetic scheme

[0061] 10 mL octadecene, 1 mL oleic acid, 1 mL oleylamine and benzyl bromide (4 mmol, or other bromide reagent) were added to a reaction flask. Start the magnetic stir. The flask was degassed for 30 min. under room temperature then for 30 min. Back filled the flask with nitrogen or other inert gas (e.g., argon). Then the solution was heated to 130 °C). 1 mmol cesium oleate and 1 mmol lead (II) oleate dissolved in 4 ml octadencene were quickly injected into the reaction flask. The solution was kept at 130 °C for 10 sec. Then, the solution was cooled to room temperature.

Example 1. Heat-up Syntheses of Blue CsPbCh ODs

[0062] 10 mL octadecene, 1 mL oleic acid, 1 mL oleylamine, 1 mmol cesium oleate, 1 mmol lead (II) oleate and 4 mmol benzyl chloride were added to a reaction flask. The flask was degassed for 30 min. under room temperature. Back filled the flask with nitrogen or argon. Then the solution was heated to 120 °C. The solution was kept at the reaction temperature for 5 min. Then, the solution was cooled to room temperature by ice bath.

Example 2. Heat-up Syntheses of Green CsPbBnQDs

[0063] 10 mL octadecene, 1 mL oleic acid, 1 ml oleylamine, 1 mmol cesium oleate, 1 rnmol lead (II) oleate and 4 mmol benzyl bromide were added to a reaction flask. The flask was degassed for 30 min. under room temperature. Back filled the flask with nitrogen or argon. Then the solution was heated to 120 °C. The solution was kept at the reaction temperature for 3 min. The, the solution was cooled to room temperature by ice bath.

Example 3. Injection Syntheses of Yellow CsPbBridisQDs

[0064] 10 mL octadecene, 1 mL oleic acid, 1 mL oleylamine, 1 mmol cesium oleate and 1 mmol lead (II) oleate were added to a reaction flask. Magnetic stir was started. The flask was degassed for 30 min. under room temperature then for 10 min. at 100 °C. Back filled the flask with nitrogen or other inert gas (e.g., argon). Then the solution was heated to reaction 140 °C. A mixture of benzyl bromide (2 mmol) and benzyl iodide (2 mmol) was quickly injected into the reaction flask. After S seconds, the solution was cooled to room temperature by ice bath.

Example 4. Injection Syntheses of Red CsPbh QDs

[0065] 10 mL octadecene, 1 mL oleic acid, 1 mL oleylamine, 1 mmol cesium oleate and 1 mmol lead (II) oleate were added to a reaction flask. Magnetic stir was started. The flask was degassed for 30 min. under room temperature then for 10 min. at 100 °C. Back filled the flask with nitrogen or other inert gas (e.g., argon). Then the solution was heated to 140 °C. Benzyl iodide (4 mmol) was quickly injected into the reaction flask. After S seconds, the solution was cooled to room temperature by ice bath.

Example 4. Reverse Injection Syntheses of Red CsPbh QDs

[0066] 10 mL octadecene and benzyl iodide (4 mmol) were added to a reaction flask. Magnetic stir was started. The flask was degassed for 30 min. under room temperature. Back filled the flask with nitrogen or other inert gas (e.g., argon). Then the solution was heated to 110 °C. 1 mmol cesium oleate and 1 mmol lead (II) oleate dissolved in 4 ml octandecene were quickly injected into the reaction flask. After 30 seconds, the solution was cooled to room temperature by ice bath. [0067] Applicant's disclosure is described herein in preferred embodiments with reference to the Figures, in which like numbers represent the same or similar elements.

Reference throughout this specification to "one embodiment," "an embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of die phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0068] The described features, structures, or characteristics of Applicant's disclosure may be combined in any suitable manner in one or more embodiments. In the description herein, numerous specific details are recited to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that Applicant's composition and/or method may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure.

[0069] In this specification and the appended claims, the singular forms "a," "an," and "the" include plural reference, unless the context clearly dictates otherwise.

[0070] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described. Methods recited herein may be carried out in any order that is logically possible, in addition to a particular order disclosed.

Incorporation by Reference

[0071] References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, web contents, have been made in this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material explicitly set forth herein is only incorporated to the extent that no conflict arises between that incorporated material and the present disclosure material. In the event of a conflict, the conflict is to be resolved in favor of the present disclosure as the preferred disclosure.

Equivalents

[0072] The representative examples are intended to help illustrate the invention, and are not intended to, nor should they be construed to, limit the scope of the invention. Indeed, various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including the examples and the references to the scientific and patent literature included herein. The examples contain important additional information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof.