THERMOELECTRIC POLYMER COMPOSITES

DETAILED DESCRIPTION

Related Applications

[0001] This application claims priority from U.S. Provisional Patent Application Ser. No. 62/163,206, filed May 18, 2015, which is hereby

incorporated by reference in its entirety

Field of the Disclosure

[0002] The present disclosure is directed to thermoelectric organic composites, and in particular to thermoelectric polymer composites that include particle inclusions for increasing the conductivity and composite power factor.

Background

[0003] There is growing interest in solution-deposited polymer-based composites for ambient temperature cooling and power generation on the microwatt-to-watt-scale where sufficient power is more critical than high efficiency. Such composites combine solution processing, mechanical flexibility, and potentially low thermal conductivity with sufficient power factor (PF), contributing to high values of the figure of merit, ZT = S ² OT/K, where S is Seebeck coefficient, σ is electronic conductivity, S ² o is PF, T is absolute temperature, and κ is thermal conductivity. A ZT >1 is considered the threshold for general commercial viability, although materials with a ZT of less than 1 can be important, for example, in applications where form and composition factors outweigh efficiency, such as medical or mobile applications. [0004] Most prior work in polymer thermoelectrics has been done on hole-carrying (p-type) polymers, especially poly(ethylenedioxythiophene) (PEDOT), sometimes mixed with heavy element compound semiconductors, having PF values >100 μνν/mK ² that lead to ZT >0.1 . PEDOT is currently the most studied TE polymer or host matrix for hybrid polymer-inorganic composites, with the highest ZT reported. It has been suggested that PEDOT can exhibit ZT values as great as 0.4 through optimal doping.

[0005] There are far fewer reports of electron-carrying (n-type) thermoelectric polymers, which are needed for completing flexible thermoelectric modules. Of the currently available n-type materials, fullerenes and powder- processed organometallic poly(Ni 1 , 1 ,2,2-ethenetetrathiolate) derivatives have shown high thermoelectric performance. Zhu et al. achieved PFs from 6-60 μνν/cmK ² (S around -100 to -150 μν/Κ, and conductivities of 5-40 S/cm) from metal coordination n- and p-type structures, leading to ZT near 0.1 at ambient temperature and 0.2 at 130 °C. Zhu et al., Organic thermoelectric materials and devices based on p- and n-type poly(metal thiolate)s, Advanced Materials, 2012. However, these materials are completely insoluble.

[0006] The few results obtained so far regarding solution-processable materials have been on imide-containing polymers, or imide-based small molecules, without inorganic additives. The first was an all solution-processable n-type polymer having very simple chemical structure; S was around -40 μν/Κ. Schlitz et al. demonstrated solution doping of a high mobility n-type polymer, poly[N,N'-bis(2-octyl-dodecyl)-1 ,4,5,8-napthalenedicarboximide2,6-diyl]-alt-5,5'- (2,2'-bithiophene)] (P(NDIOD-T2), using dihydro-1 H-benzoimidazol-2-yl (N-DBI) derivatives as potential dopants. Schiltz et al., Solubility-limited extrinsic n-type doping of a high electron mobility polymer for thermoelectric applications, Adv. Mater. 26, 2014, 2825-2830. Schiltz et al. achieved electrical conductivities of nearly 0.01 S/cm and PF of 0.6 W/mK ² . Segalman and coworkers showed record-high thermoelectric performance for solution-processed perylene diimide molecules, which could be designed with doping atoms separated by spacers, resulting in σ of 0.4 S/cm, S around -180 μν/Κ, and a PF of 1 .4 μνν/mK ² . R. A. Segalman, Power factor enhancement in solution-processed organic n-type thermoelectrics through molecular design, Advanced Materials 26, 2014.

[0007] Alkali metal are known to have excellent reducing properties for n-type polymers. However, they are not easy to handle in open air. Lefenfeld has showed convenient way to encapsulate the sodium metals into nano structured silica gel. Sodium silica gel (Na-SG) particles were used as reducing agent for both the polymers. Encapsulation decreases the danger of handling sodium metal in ambient atmosphere while maintaining its reducing properties. See, Dye, J.L.; Urbin, S.A.; Redko, M.Y.; Jackson, J.E.; Lefenfeld, M.; J. Am. Chem. Soc. 2005, 127, 9338; and Costanzo, M.J.; Patel, M.N. ; Petersen, K.A.; Vogt, P.F.; Tetrahedron Lett. 2009, 50, 5463, both of which references are

incorporated herein by reference in their entirety.

[0008] Novel materials with enhanced theremoeletric performance and/or techniques for enhancing thermoelectric performance would be a welcome advancement in the art. SUMMARY

[0009] An embodiment of the present disclosure is directed to a thermoelectric composite. The composite comprises at least one organic matrix material that may be electrically reduced or oxidized; and at least one particle inclusion comprising an insulating material in which a strong oxidizing dopant or strong reducing dopant is encapsulated.

[0010] Another embodiment of the present disclosure is directed to a thermoelectric polymer composite. The composite comprises at least one n-type polymer selected from semiconducting polymers and conducting polymers; and at least one particle inclusion comprising an insulating material in which a strong reducing dopant is encapsulated.

[0011] Yet another embodiment of the present disclosure is directed to a thermoelectric polymer composite. The composite comprises at least one n-type polymer selected from semiconducting polymers and conducting polymers; and at least one particle inclusion comprising a strong reducing inorganic dopant.

[0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present teachings, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrates embodiments of the present teachings and together with the description, serve to explain the principles of the present teachings. [0014] FIG. 1A shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0015] FIG. 1 B shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0016] FIG. 1 C shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0017] FIG. 1 D shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0018] FIG. 1 E shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0019] FIG. 1 F shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0020] FIG. 1 G shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0021] FIG. 1 H shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0022] FIG. 1 1 shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0023] FIG. 1 J shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0024] FIG. 1 K shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0025] FIG. 1 L shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure. [0026] FIG. 1 M shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0027] FIG. 1 N shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0028] FIG. 10 shows examples of suitable polymers for thermoelectric composites, according to embodiments of the present disclosure.

[0029] FIG. 2 shows electrical conductivity of undoped and Na-SG particle doped N1 and N2 polymers at varying weight percentages.

[0030] FIG. 3 shows Seebeck co-efficient of undoped and Na-SG particle doped N1 and N2 polymers at varying weight percentages.

[0031] FIG. 4 shows the Power factor of undoped and Na-SG particles doped N1 and N2 polymers at varying weight percentages.

[0032] It should be noted that some details of the figure have been simplified and are drawn to facilitate understanding of the embodiments rather than to maintain strict structural accuracy, detail, and scale.

DESCRIPTION OF THE EMBODIMENTS

[0033] Reference will now be made in detail to embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. In the drawings, like reference numerals have been used throughout to designate identical elements. In the following description, reference is made to the accompanying drawing that forms a part thereof, and in which is shown by way of illustration a specific exemplary embodiment in which the present teachings may be practiced. The following description is, therefore, merely exemplary.

[0034] The present disclosure is directed to a composition comprising a soluble organic matrix material, such as an organic compound or organic based material mixture that may be electrically reduced or oxidized, for example reduced at <2 V more negative than saturated calomel electrode (SCE), more preferably at <1 V more negative than SCE. A preferable form of the organic matrix material comprises a soluble polymer, as will be described in greater detail below, though molecular solids and blends comprising polymers, molecular solids, or both are contemplated. Other examples of matrix materials include organic materials that can be formed into semiconducting or conducting polymers from solution, such as conjugated molecules or oligomers with side chains that provide solubility and/or self-assembling capability.

[0035] To the reducible or oxidizable organic matrix material is added a solid in particulate form. The solid particle has reducing or oxidizing power in that it comprises atomic or molecular subunits with which reduction or oxidation of the organic compound or material is favorable, e.g. the oxidation potential of the solid is at a higher magnitude negative potential than the reduction potential of the organic. For example, if the reduction potential of the organic is -1 V vs. SCE, the oxidation potential of an atomic or molecular subunit of the solid is more negative than -1 V vs. SCE, preferably more negative than -1 .5 V vs. SCE. For purposes of the present application, "strong" oxidizing (or reducing) potential is defined to be more than 0.5 V more negative (positive) than the reduction (oxidation) potential of the polymer in which the particle is contained for n (p) polymers, respectively, where the reduction/oxidation potentials for the materials are measured by comparison with a saturated calomel electrode ("SCE").

[0036] An embodiment of the present application is directed to a thermoelectric composite. The composite comprises at least one organic matrix material and at least one particle inclusion. Examples of suitable organic materials include semiconducting polymers and conducting polymers, such as any of the n-type or p-type polymers described herein. In an embodiment, the at least one particle inclusion comprises an insulating material, such as a silica gel or other silicate or gel material, in which a strong oxidizing dopant or strong reducing dopant is encapsulated.

[0037] The thermoelectric composite includes at least one particle inclusion having one or more dimensions of 1 mm or less, preferably 10 microns or less, and even more preferably 1 micron or less. The particle is a domain of a solid phase material, rather than a single molecular unit. In an embodiment, the inclusions are not individual molecules, polymer chains (e.g., long chain of SiO or PN bonds or other polymers) or carbon nanotubes. In an embodiment, the particle inclusion has at least one dimension measurable along an arbitrary axis, x, of 10 nm or more and a second dimension that is measurable along an axis, y, that is perpendicular to the x axis, the second dimension being at least 3 nm or more. Individual molecules and polymer chains are generally excluded by these dimensions because most molecules have no dimension as large as 10 nm, and polymer chains generally do not have a "thickness" or diameter of as much as 3 nm. A third dimension measurable along an axis z that is perpendicular to the x axis and y axis can be arbitrarily thin to allow for very thin flakes or platelets, for example. In an embodiment, the particle includes at least one dimension in the range of 10 nm to 1 mm, such as 100 nm to 0.1 mm. A sufficient amount of the particle inclusion is distributed within the polymer so that the power factor of the composite is greater that the power factor of either the polymer or the particle inclusion separately.

[0038] Where polymers are employed in the thermoelectric composite, they can be any suitable semiconducting or conducting organic polymers, including either n-type or p-type polymers. Examples of suitable semiconducting and conducting polymers are well known in the art. As used herein, the term "semiconducting polymer" is defined to mean organic polymers having a conductivity in their pure form ranging from about 10 ^"6 S/cm to about 1000 S/cm at room temperature (23 °C). The term "conducting polymer" is defined to mean any organic polymer having a conductivity at the higher range of conductivities for a semiconducting polymer, e.g. > 0.01 S/cm. The term encompasses polymers which may attain this higher range of conductivity as the result of the incorporation of additives, often termed "dopants". Unless stated otherwise, all conductivities stated herein are at room temperature (23 °C). As one of ordinary skill in the art readily understands, conductivity for conducting polymers generally increases with increasing temperatures.

N-TYPE AND P-TYPE POLYMERS

[0039] In one embodiment, the polymer is an n-type polymer, meaning a semiconducting or conducting polymer where the majority charge carriers are electrons. Examples of suitable n-type polymers include polymers comprising at least one polymer unit chosen from pyromellitic diimide units, napthalenetetracarboxylic diimide units, perylenetetracarboxylic diimide units, heterocyclic tetracarboxylic diimide units, cyano-substituted vinyl groups, cyanomethylidene-substituted unsaturated rings, fullerene units,

pyrazinophthalimide units, triazoledipyridyl units, benzodifuranone units, and benzodipyrrolidone units. Enhancement of the n-type activity can occur when cationic species including protons or metal ions coordinate to sites on the polymers. Side chains can be appended to the various subunits to promote solubility, compatibilization with additives, processability, chemical stability, and the like. The n-type polymers preferably comprise aromatic or heteroaromatic tetracarboxylic diimide subunits. The imide nitrogens on these subunits are preferred sites for side chain attachment. Such side chains can include linear alkyi chains preferably 4-12 carbons long, branched alkyi chains of 6-24 carbons or 6-22 carbons long, and semifluorinated alkyi chains comprising 1 -6 CH ₂ or CH ₃ groups and 1 -10 CF ₂ or CF ₃ groups. Phenylene and oxy groups can be interposed among the carbons of these side chains.

[0040] One or more additional conjugating subunits, such as 1 ,4- phenylenediyl, 1 ,2-ethylidene, 1 ,2-ethynylidene, and diketopyrrolopyrrole, may be present in the n-type semiconducting polymers. Still other conjugating subunits can include, for example, 2,6-naphthalenediyl, 2,5-thiophenediyl, 5,5'- (2,2'-bithiophenediyl), and similar subunits with the possibility that heteroatoms, such as N or O, of the above listed conjugating subunits could be substituted for some of the ring carbons and/or that side chain substituents could be substituted for some of the hydrogen on the ring, if stability and conjugation are maintained. [0041] Specific examples of suitable n-type tetracarboxylic diimide polymers include the following compounds found in FIGS. 1A to 1 E and 1 G: PTCDI-2T, PTCDI-AF4A, NTCDI2DT-2T, NTCDI-AF4A, NTCDI-FO, NTCDI- FCN2, NTCDI-FCNA, NTCDI-BPFN, PyDIA6H4F and PyDI2T6H4F, where "n" designates the number of repeating units. The number of repeating units can be chosen as desired and determining the appropriate range of repeating units is well within the capabilities of one of ordinary skill in the art. As further examples, any of the alkyl substituents of the n-type compounds of the figures of this application (including those of FIGS. 1A to 1 E, 1 G and 1 H), as well as any of the alkyl substituents of the n-type compounds in Examples 1 to 20, can be replaced by any linear alkyl chains 4-12 carbons long or branched alkyl chains of 6-24 carbons or 6-22 carbons long, or semifluorinated alkyl chains comprising 1 -6 CH ₂ or CH ₃ groups and 1 -10 CF ₂ or CF ₃ groups. For instance, the alkyl groups on the nitrogen atoms of P1 and P2 of FIG. 1 H can each be replaced with linear alkyl chains of 4 to 12 carbon atoms long, branched alkyl chains of 6 to 24 carbon atoms long or semifluorinated alkyl chains comprising 1 -6 CH ₂ or CH ₃ groups and 1 -10 CF ₂ or CF ₃ groups.

[0042] Other examples of suitable n-type polymers include PyDi- ethynylene polymers, such as poly(PyDi-ethynylene) and poly(PyDi-ethynylene)- 5FPE (also known as "5FPE-PyDI", and sometimes referred to herein as P1 ); and poly{[/V,/V'-bis(2-octyldodecyl)-naphthalene-1 ,4,5,8-bis(dicarboximide)-2,6- diyl]-alt-5,5'-(2,2'-bithiophene)}, also known as P(NDI20D-T2) (commercially available as Polyera Activlnk™ N2200 from Polyera Corporation of Skokie, Illinois) and referred to herein as P2). Chemical structures for P1 and P2 are shown in FIG. 1 H, where "n" refers to the number of repeating units. The 'n' in the formulae of FIG. 1 H represents the number of repeating units of the polymer. The structure of P1 includes a pentafluorophenyl end cap. In an embodiment, an n-type polymer the same as P1 but without the end caps could also be used.

[0043] The weight average molecular weight of the n-type polymers can range, for example from 1000 daltons or more, such as 2000 daltons to about 200,000 daltons, or about 10,000 daltons to about 150,000 daltons or about 20,000 daltons to about 150,000 daltons. Polydispersity for the polymers can be 1 or greater, such as from about 1 .5 to about 10, or about 1 .6 to about 8.

[0044] In another embodiment, the polymer is a p-type polymer, meaning a semiconducting or conducting polymer where the majority charge carriers are holes. Examples of suitable p-type polymers include polymers comprising at least one polymer unit chosen from thiophene units, 3-alkylthiophene units, thienothiophene units, pyrrole units, furan units, carbazole units, aniline units, ethylenedioxythiophene units, ethylenedithiolate units, methoxyphenylenvinylene units, or dialkoxyphenylenevinylene units. Any one, two, three, four or more of the p-type polymer units can be employed in the polymer.

[0045] As was described for n-type polymers, side chains may be appended to enhance various physical and chemical attributes. Linear or branched alkyl chains of about 4 to about 22 carbons, such as about 4 to about 20 carbons, such as about 4 to about 12 carbons in length are preferred substituents for thiophene rings and other subunits of p-type polymers.

[0046] It should be recognized that additional conjugating subunits, such as 1 ,4-phenylenediyl, 1 ,2-ethylidene, 1 ,2-ethynylidene, and diketopyrrolopyrrole, may be present in either p-type or n-type semiconducting polymers. Still other conjugating subunits can include, for example, 2,6-naphthalenediyl, 2,5- thiophenediyl, 5,5'-(2,2'-bithiophenediyl), and similar subunits with the possibility that heteroatoms, such as N or O, of the above listed conjugating subunits could be substituted for some of the ring carbons and/or that side chain substituents could be substituted for some of the hydrogen on the ring, if stability and conjugation are maintained.

[0047] Examples of suitable p-type polymers include the PQT12,

PQT12S and P4 polymers shown in FIGS. 1 F and 1 H, where "n" designates the number of repeating units. The number of repeating units can be chosen as desired and determining the appropriate range of repeating units is well within the capabilities of one of ordinary skill in the art. Other examples of p-type polymers include the polymers of FIGS. 1 1 to 10, as well as poly(3- hexylthiophene) ("P3HT") and poly(ethylenedioxythiophene) ("PEDOT"), all of which are known in the art and/or are commercially available. Still other examples and designations of p-type polymers include polythiophene (PT), polyalkylthiophene, polyaniline, polyacetylene, polypyrrole, poly(p-phenylene sulfide), poly(p-phenylene vinylene) (PPV), polyindole, polypyrene,

polycarbazole, polyazulene, polyazepine, polyfluorene, and polynaphthalene. As further examples, any of the alkyl groups in the p-type polymers shown in any of the figures of this application can be replaced with linear or branched alkyl chains of about 4 to about 22 carbons, such as about 4 to about 20 carbons, such as about 4 to about 12 carbons. [0048] As stated, the 'n' in each of the formulae of FIG. 1 A to 10 represents the number of repeating units of the polymer. Example values for n can range from about 5 to about 1000, such as about 20 to about 1000 or about 50 to about 500 or about 50 to about 250. Values for n can be chosen to achieve the desired solid film organization and a usable solubility. The desired values for n may depend on the particular repeat units employed, with polymers having larger repeat units or greater numbers of ring structures potentially employing lower values for n. The above example ranges can apply to any of the p and n type polymers of the present disclosure. One of ordinary skill in the art would be able to determine a desired value for 'n' for any of the polymers described herein.

[0049] Polymer blends can be employed in the composites of the present disclosure, including blends of any of the above n-type polymers to form an n-type composite or any of the above p-type polymers to form a p-type composite. In an embodiment, the blend can comprise at least two polymers of differing carrier energy levels. An example of a p-type polymer blend comprises both PQT12 and PQT12S (same as PQT12 except for sulfur atoms are inserted between the thiophene rings and the dodecyl side chains, making them dodecylthio groups, which results in lower carrier energy level and easier hole- doping when compared to PQT12). The same principle can be applied to n- doped polymers. For example, any of the above n-type polymers can be employed as a first polymer, which is blended with a second polymer that is the same as the first polymer except that it is synthesized with additional halo or cyano substituents to lower its carrier (electron) energy level. Thus, the blend includes a first polymer with a relatively high carrier energy level and a second polymer with a lower carrier energy level compared with the first polymer.

PARTICLE INCLUSIONS

[0050] In an embodiment, the particle inclusions employed in the thermoelectric polymer composite comprise a silica gel in which a strong oxidizing dopant or strong reducing dopant is encapsulated. In embodiments in which the particle inclusion includes a strong reducing dopant encapsulated in the silica gel, the strong reducing dopant can comprise at least one alkali metal, such as Lithium (Li), Sodium (Na), Potassium (K), Rubidium (RB) and Cesium (Cs), or any combination thereof. In an embodiment, the at least one alkali metal is chosen from sodium, potassium or combinations thereof. Unlike many doped conductive polymers that employ semiconductive and conductive particles, the silica gel encapsulated particle inclusions of the present disclosure have the property of being electrically insulating.

[0051] Strong oxidizing or reducing materials, such as alkali metals, are generally unstable, reacting quickly with their surrounding environment and thereby lose their oxidizing or reducing power. The insulating encapsulation employed in the particles of the present disclosure acts to protect the dopants in a form that maintains there strong oxidizing and reducing ability. The dopant in the particle inclusion can be in any form that is suitable for encapsulation in the silica gel and that will provide the desired reducing or oxidizing ability. For example, the reducing dopant can be an alkali metal or alkali metal compound in nanoparticle form, such as nanoparticles comprising silicon and/or oxygen and at least one of sodium, potassium or sodium potassium alloy (e.g., Na ₂ K or K ₂ Na). Examples include alkali metal silicides in nanoparticle form, such as

nanoparticles of Na ₄ Si ₄ . In an embodiment, at least some of the alkali metal dopant can be in an atomic or cluster form, such as ionized atoms or partially ionized cluster cations of sodium or potassium with chemically active electron equivalents as counterions,(e.g., inorganic electrides of sodium or potassium). While the chemical nature of these electron equivalents may not be well defined, they are distinguished by their ability to serve as reducing equivalents in chemical transformations, such as the doping of n-type semiconducting polymers. Note that standard "doped" glass particles may have various nonsilicon elements mixed in but do not have particular reducing or oxidizing power.

[0052] Examples of commercially available silica gels encapsulating strong reducing dopants include alkali metal silica gels ("M-SG"), stages 0, I and II, made by SIGNA and available from SIGMA-ALDRICH. These materials are described, for example, in the article by James L. Dye, et al., which is entitled, "Alkali Metals Plus Silica Gel: Powerful Reducing Agents and Convenient Hydrogen Sources," J. Am. Chem. Soc , 2005, 127, 9338-9339, the disclosure of which is incorporated herein by reference in its entirety. Specific examples include Na-SG, Na ₂ K-SG and K ₂ Na-SG, which can be in a Stage 0, Stage I or Stage II powder form as described in the article entitled "SIGMA-ALDRICH Chemical Syntheses - Alkali Metal Silica Gels from SiGNa,"

http:/ wvv siqmaakJnch com/chemistry/^

¾potl;qh s/aikaii-S:l;ca--qe;s html, the disclosure of which is incorporated herein by reference in its entirety. SiGNa's alkali metal-silica gels have metal loadings up to 40 wt.% and are available in three varieties: 1 ) Stage 0 M-SG, which is a pyrophoric, free-flowing, shiny black powder that is capable of reducing Teflon® in its solid state; 2) Stage I M-SG, which is a dry air-stable, free-flowing, non- pyrophoric black powder that retains the reactivity equivalent of its parent alkali metal; and 3) Stage II M-SG, which is an air-stable, free-flowing, non-pyrophoric black powder that contains nano-crystalline domains of metal silicide.

[0053] Other reducing solids are contemplated in addition to or in place of the silica gel encapsulated alkali metals discussed above. For Example, modified inorganic compounds that can form "ate" complexes such as SnC or CuCI ₂ or ZnO reacted with lithium metal are contemplated. The "ate" complexes could optionally be incorporated into the silicate materials or formed as neat particles without silica encapsulation. These very reactive "ate" complexes can form crystallites by, for example, precipitating from a solution, and when exposed to the air, the outside may become oxidized and less reactive or unreactive, but inside, there can still be active reducing power analogous to what happens in the silicates describe above. Thus, even in the case where the complexes are formed as neat particles without encapsulation, the particles may still effectively be encapsulated by reaction with their environment. A possible difference between the reducing agents encapsulated solely by reaction with the environment and those that are incorporated into encapsulation (e.g., silica) by other means is that the insulating encapsulation employed in the particles can be different than the insulation that is formed as a product of the reducing particle with an oxygen environment. [0054] The "ate complexes can be formed by reaction a reducing compound (e.g., SnCI ₂ or CuCI ₂ or ZnO) with lithium metal or sodium, or with an organolithium compound such as methyllithium or butyllithium to form an alkylated "ate" complex. As an example, a compound like stannous chloride mixed in tetrahydrofuran or dioxane or a similar ether solvent with lithium or sodium granules may form a suitable "ate" complex. Other examples include suitable organic copper "ate" complexes with lithium (e.g., diorganocuprates of lithium or sodium), which are known in the art. Some of these compounds may have been developed for making carbon-carbon bonds. Examples of suitable organic copper complexes are described in a paper by Robert P. Davies, entitled "The structures of lithium and magnesium organocuprates and related species," Coordination Chemistry Reviews 255 (201 1 ) 1226-1251 ; and a paper by Ruth M. Gschwind, entitled, "Organocuprates and Diamagnetic Copper Complexes: Structures and NMR Spectroscopic Structure Elucidation in Solution," Chem. Rev. 2008, 108, 3029-3053, the disclosure of both of which papers are incorporated herein by reference in their entirety.

[0055] Silica particles with strong oxidizing power are also contemplated.

Any suitable particles comprising a dopant with oxidizing power encapsulated in an insulating material could be employed. Examples include sol-gel-synthesized silica particles (using techniques shown, for example, in "Chemical Routes in the Synthesis of Nanomaterials Using the Sol-Gel Process", by John D. MacKenzie, et al. , Acc. Chem. Res. 2007, 40, 810-818; and Synthesis of Silica

Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nanocomposites— A Review, by Ismail Ab Rahman et al., Hindawi Publishing Corporation, Journal of Nanomaterials, Volume 2012, Article ID 132424, 15 pages, the disclosure of both of which references are incorporated herein by reference in their entirety) where the synthesis is conducted using acid catalysis in the presence of strong oxidizing agents capable of doping p-type semiconducting polymers, such as any of the p- type polymers listed in this disclosure. Examples of suitable strong oxidizing agents include ferric chloride, ferric nitrate, cobalt(lll) nitrate, lead tetra-acetate, cerium (IV) ammonium nitrate, nitrosyl tetrafluoroborate, potassium

permanganate, chromium trioxide, and other inorganic reagents with similar oxidizing power.

[0056] Still other particle inclusions can be used, including those that potentially may not be encapsulated. For example, inorganic reducing agents in powdered form such as sodium borohydride and lithium borohydride are contemplated.

[0057] In embodiments, thermoelectric composites can be formed by combining any of the p-type polymers described herein with any of the oxidizing particle inclusions described herein. In an alternative embodiment,

thermoelectric composites can be formed by combining any of the n-type polymers described herein with any of the reducing particle inclusions described herein. For example, any of the n-type polymers describe herein can be mixed with the alkali metal-SG reducing particles to form thermoelectric composites.

[0058] The amount of particle inclusions that can be included in the compositions of the present disclosure can be any suitable amount that will provide the desired properties. The exact amount may depend on a variety of factors, including such things as the particular materials employed and the amount of dopant in the gel encapsulated particle inclusions. For example, the amount of particle inclusions in the compositions can range from about 10% by weight or more, such as about 20% by weight to about 80% by weight, or about 40% by weight to about 60% by weight.

[0059] In an embodiment, the particle inclusion increases the

conductivity to a desired value. As an example, the conductivity is greater than 1x10 ^"5 S/cm at 23 °C, such as about 1x10 ^"5 to about 1000 S/cm, such as about 1x10 ^"5 to about 1 S/cm, such as about 1x10 ^"4 to about 0.1 S/cm, or about 1 x10 ^"4 to about 1 x10 ^"2 S/cm at 23 °C. In an embodiment, the conductivity is 1 S/cm or more, such as 1 S/cm to about 1000 S/cm at 23 °C. The particle inclusion may also increase the power factor of the composite to be greater than the power factor of either the polymer or the particle inclusion separately. In an

embodiment, the thermoelectric polymer composite has a power factor that is greater than 0.05 μνν/mK ² at 23 °C.

[0060] The particle inclusion is capable of donating an equilibrium concentration of charge carriers to the polymer. The donation of charge carriers, such as electrons, is enthalpically driven. This is due, at least in part, to the strong oxidation or reducing power of the particle inclusions.

[0061] The inclusions can be millimeter sized particles or smaller, meaning that the inclusions have a least one dimension that is 1 mm or less, preferably 10 microns or less, and even more preferably 1 micron or less.

However, the particle inclusion also has at least one dimension of 10 nm or more, and a second dimension of 3 nm or more, e.g., the particle is a domain of a solid phase material, rather than a molecular unit.

[0062] For example, particle inclusions can be micro or nanosized. There are also several competing arguments for either macrocrystals or nano-sized inclusions being more desirable. For one, smaller dopants have high tendency to diffuse in organic systems, leading to detrimental instability. M. L. Tietze, et al., Self-passivation of molecular n-type doping during air exposure using a highly efficient air-instable dopant, PSS, 2013, the disclosure of which is hereby incorporated by reference in its entirety. Nanostructuring increases surface area to volume ratio greatly at cost of greater series contact resistances. However, phononic thermal conductivity is greatly reduced due to the abundance of interface with nanostructuring.

EXAMPLES

Example 1

[0063] The n-type polymer Poly{[N,N'-bis(2-decyl-tetradecyl)- 1 ,4,5,8- naphthalene diimide-2,6-diyl]-alt-(2,2'-bithiophene-5,5'-diyl)} (Referred to herein as NTCDI2DT-2T or NTCDI-2T) was made using the following procedure.

NTCDI2DT-2T

[0064] To a solution of /V,/V'-bis(2-decyl-tetradecyl)-2,6- dibromonaphthalene diimide (0.20 mmol, 219.5 mg), 5,5'-bis(trimethylstannyl)- 2,2'-bithiophene (0.20 mmol, 98.4 mg), and anhydrous chlorobenzene (5 ml_) under nitrogen were added tris(dibenzylideneacetone)dipalladium(0) (10 μιηοΙ, 9 mg), and tri(otolyl)phosphine (40 μιηοΙ, 12 mg) . The mixture was heated at 1 15 °C for 48 h with vigorously stirring. Bromobenzene (0.1 ml) was then added under nitrogen and the reaction mixture was maintained at 1 15 °C for an additional 12 h. After cooling down to room temperature, the reaction mixture was poured into methanol (200 mL) and HCI (10 mL) and then stirred for 3 h. The polymer was filtered and subjected to Soxhiet extraction with acetone (24 h), Hexane (24 h) and chloroform (24 h). The chloroform fraction was concentrated at reduced pressure and precipitated in methanol. The resulting solid was collected by filtration and dried under vacuum to afford the desired polymer (167 mg, 75.8%) as a deep blue solid.

Example 2

[0065] The n-type polymer, Poly{[N,N'-bis(2-decyl-tetradecyl)-1 ,4,5,8- naphthalene diimide-2,6-diyl]-alt-(1 ,4- Diethynyltetrafluorobenzene)} (Also referred to as NTCDI-AF4A) was made using the following procedure.

[0066] To a mixture of N A/,/V'-bis(2-decyl-tetradecyl)-2,6- dibromonaphthalene diimide (0.14 mmol, 153.7 mg), 1 ,4- Diethynyltetrafluorobenzene (0.14 mmol, 27.7 mg), PdCI ₂ (dppf) (7 μιηοΙ, 4.9 mg) and Cul (7 μιηοΙ, 1 .3 mg) under nitrogen was added anhydrous toluene (5.6 mL) and Ν,Ν-DiisoprQpyiamine (2.8 mL). The mixture was heated at 60 °C for 48 h with vigorously stirring. The polymer was end-capped with pentafluorophenyl by adding lodopentaflurophenyl. After cooling down to room temperature, the reaction mixture was poured into methanol (200 mL) and then stirred for 30 mins. The polymer was filtered and redissolved in chlorobenzene and

reprecipitated into acetone. Then the polymer was filtered and redissolved in chlorobenzene and reprecipitated into hexane. Following filtration and dried in the vacuum, the purified polymer (98 mg, 61 .8%) was obtained as a dark green solid with metallic luster.

C ₁₀ H ₂ i

12H25 NTCDI-AF4A

Example 3

[0067] The polymer of Example 1 was mixed with silica-sodium gel (Na-

SG, stage II) made by SiGNa using the following procedure. In glove box, the polymer of example 1 and sodium-silica gel powders were weighed in separate glass vials and made up to 10 mg/mL from different organic solvents, using chlorobenzene for the polymer and THF for the silica gel, in order to promote the best solubility and dispersion. The polymer solution was placed on a hot plate (60 °C) while the solution of silica gel was held on a vortex machine (10 minutes) in order to disperse and dissolve the inorganic molecules as much as possible, which are very insoluble. The polymer was blended in the desired concentration with silica gel solution using a pipette, and vigorously stirred on the vortexer (5- 10 minutes) before drop-casting. [0068] The final blend was dropped by pipette into shallow 2D wells, which were fabricated by laying a pattern of Novec fluorinated polymer, on the glass substrates having pre-deposited metal electrodes. The result was a square centimeter film with 1 -2 micrometer thickness (from about 75 microliters of starting solution), lying over two thin metal electrodes (0.2-0.3 cm across and 1 cm wide) having a channel gap (0.3-0.5 cm across and 1 cm wide). The solvent was allowed to evaporate overnight while samples were kept in a petri dish. Next, samples were placed under low temperature (1 10-150 °C for 30 minutes), mostly to remove residual solvent. Before taking samples out for electrical measurements, the films were capped with PMMA diluted 80mg/ml in butyl acetate (spun-cast on top at 1500rpm). The final structure was baked again one last time in the glove box to remove residual solvent.

Example 4

[0069] The polymer of Example 2 was mixed with silica-sodium gel ((Na-

SG, stage II) using the same procedure as used in Example 3, except that the polymer of Example 1 was replaced with the polymer of Example 2.

[0070] Certain precursors employed in the above examples can be synthesized as described in the following additional examples.

Example 5

[0071] N-(2-decyltetradecyl)phthalimide 3. A solution of

triphenylphosphine (6.8 g, 26 mmol), phthalimide (3.83 g, 26 mmol) and 1 (7.09 g, 20 mmol) in dry THF (100 ml_) was purged with nitrogen and the

diisopropylazodicarboxylate (5.2 ml_, 26 mmol) was slowly added. After stirring for overnight at the room temperature, the solvents were removed via rotary evaporation. The pure product of 3 was isolated by silica gel chromatography (with 2: 1 hexane/DCM as the eluent) as a light yellow oil in 90% yield (8.2 g). ¹ H NMR (CDCI 3 , 300 MHz): δ ppm 7.84 (m, 2H), 7.13 (m, 2H), 3.57 (d, 2H, J = 7.2Hz), 1 .87 (m, 1 H), 1 .23 (m, 40H), 0.85 (m, 6H). The synthesis reaction for both Examples 5 and 6 are shown below.

Example 6

[0072] 2-decyl-1 -tetradecylamine 4. N-(2-decyltetradecyl) phthalimide (10 g, 0.021 mol), hydrazine hydrate (hydrazine, 65 %) (4 ml, 0.083 mol) and 100 ml methanol were stirred under nitrogen at 90 °C for 2 h. After the mixture cooled down to r.t. , the methanol was evaporated under reduced pressure, the residue diluted with 100 ml dichloromethane and washed with 10 % KOH . Aqueous layers were combined and extracted with dichloromethane (3 x 20 ml). The combined organic layers were washed with brine twice and dried over MgS0 ₄ . The solvent was removed and a yellow oil was obtained as product which was used in the next step without further purification. ¹ H NMR (300MHz, CDCIs): δ ppm 2.59 (d, 2H), 1 .45 (m, 1 H), 1 .30 (br, 40H), 0.88 (m, 6H).

Example 7

[0073] 1 ,7-dibromo-perylene-3,4:9,10-tetracarboxylic acid

bisanhydride 6. A mixture of 13.731 g (35.0 mmol) of perylene-3,4:9, 10- tetracarboxylic acid bisanhydride (5) and 200m L of concentrated sulfuric acid was stirred for 12 h at room temperature, and subsequently l ₂ (0.343 g, 1 .35 mmol) was added. The reaction mixture was heated to 85 °C, and 4.15 mL (81 mmol) of bromine was added dropwise. After bromine addition, the reaction mixture was heated for an additional 10 h at 85 °C and cooled to room temperature. The excess bromine was removed by a gentle stream of N ₂ gas. Then the reaction mixture was poured onto crushed ice (500 g), followed by the addition of H ₂ 0 (1000 mL), and then stirred at room temperature for 1 h. The resulting precipitate was separated by filtration through a G4 funnel, washed with a large amount of water, and dried in a vacuum to give 17.9 g (93%) of a red powder. This material was used for the next step without further purification. The synthesis reaction for both Examples 7 and 8 are shown below. Example 8

[0074] N,N'-bis(2-decyl-tetradecyl)-1 ,7-dibromo-3,4,9,10-perylene diimide 7. 1 ,7-Dibromoperylene-3,4,9,10-tetracarboxylic acid dianhydride (2.74 g, 4.98 mmol) in 200 mL of n-BuOH/H ₂ 0 (1 :1 , v/v) was sonicated for 10 min. 2- Decyl-1-tetradecylamine (5.22 g, 14.70 mmol) was added and the reaction mixture was stirred at 80 °C for 17 h under nitrogen. Concentrated aqueous HCI (10 mL) was added and the mixture was stirred at room temperature for 30 min. The mixture was extracted with DCM (2x75 mL), washed with water (2x100 mL), and dried over anhydrous MgS0 ₄ . The solvent was removed and the residue was purified by column chromatography over silica gel eluting with

CH ₂ CI ₂ /hexane (1 :3) to give a red solid (3.4 g, 56%). ¹ H NMR (400 MHz, CDCI ₃ ): δ 9.50 (d, J = 8 Hz, 2H), 8.93 (s, 2H), 8.71 (d, J = 8.0 Hz, 2H), 4.14 (d, J = 7.2 Hz, 4H), 2.00 (m, 2H), 1.5-1 .1 (m, 80H), 0.84 (m, 12H).

7

Exam le 9

[0075] 2,6-dibromonaphthalene-1 ,4:5,8-tetracarboxylic acid dianhydride 10. A mixture of 1 ,4,5,8-naphthalenetetracarboxylic dianhydride (9.332 g, 34.8 mmol) and oleum (20% S0 ₃ , 50 mL) was stirred at room temperature for 1 h. A solution of dibromoisocyanuric acid (10 g, 34.8 mmol) in oleum (25 mL) was stirred at room temperature for 1 h. The dibromoisocyanuric acid solution was then added into the 1 ,4,5,8-naphthalenetetracarboxylic dianhydride dropwise, and the resulting mixture was warmed to 40 ° C and maintained at this temperature for 5 h. After cooling to room temperature, the reaction mixture was poured onto crushed ice (500 g), followed by the addition of H ₂ 0 (1000 mL), and then stirred at room temperature for 1 h. The resulting precipitate was separated by filtration through a G4 funnel, washed with a large amount of water, and dried in a vacuum to 14.2 g (96%) of a greenish-yellow solid. This material was used for the next step without further purification. The synthesis reaction for Examples 9 and 10 is shown below.

Example 10

[0076] N,N'-Bis(2-decyltetradecyl)-2,6-dibromo-1 ,4:5,8-naphthalene Diimide 11. NTCDA-Br2 (10) (3.407 g, 8 mmol) was added to a 250 mL round bottom flask along with glacial acetic acid (60 mL) and 2-decyltetradecan-1 - amine (7.073 g, 20 mmol). The reaction mixture was refluxed under N ₂ for 2 h and then poured onto Methanol, forming a precipitate that was subsequently filtered and washed with methanol. The crude product was purified via column chromatography over silica gel (eluent: dichloromethane/ hexane, 1 :3). The resulting orange solid was further purified via recrystallization from hexanes to give NTCDI-Br2 ( 11 ) as yellow crystals. (1 .84 g, 21 % assuming pure 10). ¹ H NMR (300 MHz, CDCI ₃ ): δ ppm 9.00 (s, 2H), 4.14 (d, J = 7.5 Hz, 4H), 1 .99 (m, 2H), 1 .23 (m, 80H), 0.87 (t, 12H).

11

Example 1 1

[0077] 1 ,4-bis((trimethylsilyl)ethynyl)tetrafluorobenzene 14. To a solution of 1 ,4-dibromo-tetraflurobenzene (1 .62 g, 5.26 mmol) in anhydrous N,N~ Diisopropylamine (50 mL) was added Cul (188.5 mg, 0.99 mmol) and

Pd(PPh ₃ ) ₂ CI ₂ (347 mg, 0.49 mmol). After the solution was deoxygenated with nitrogen for 30 min, trimethylsilylacetylene (7.1 mL, 50.26 mmol) was then added via syringe and the mixture was heated to 60 °C for 24 h. The solution was then allowed to cool to room temperature and the solvent was removed under vacuum. The crude product was purified by column chromatography on silica gel with a solvent combination of hexane/ CH ₂ CI ₂ (1 :2, v/v) as eluent. The resulting light yellow solid was further purified via recrystallization from ethanol to give 950.2 mg (52.7 %) of 14 as white crystals. ¹ HNMR(300MHz, CDCI ₃ ): δ ppm

0.27 (s, 18H). ¹⁹ F NMR(282.4 MHz, CDCI ₃ ): δ ppm -136.5. The synthesis reactions for Examples 1 1 and 12 are shown below. Example 12

[0078] 1 ,4-Diethynyltetrafluorobenzene 15. A mixture of 1 ,4- Bis((trimethylsilyl)ethynyl))-tetraflurobenzene (547.5 mg, 1 .6 mmol), 1 mL H ₂ 0 and KOH (28 mg, 0.5 mmol) in MeOH (9 mL) was stirred at room temperature for 30 mins under nitrogen in a dark environment. The mixture was extracted with hexane (2 χ 50 mL), washed with water (2 χ 100 mL), and dried over anhydrous MgS0 ₄ . The solvent mixture was evaporated in vacuo to leave a white crystals. The crystals was washed by hexane to afford a white solid of 1 ,4- dietynyltetraflurobenzene with a yield of 55.6 % (176 mg). ¹ H NMR(300MHz, CDCI ₃ ): δ ppm 3.72(s, 2H). ¹⁹ F NMR(282.4 MHz, CDCI ₃ ): δ ppm -135.8.

Example 13

[0079] Bis(4-bromophenyl)fumaronitrile 17. 4-Bromobenzylcyanide (5 g, 25.5 mmol) and one equivalent amount of iodine (6.573 g, 25.5 mmol) were dissolved in dry diethyl ether (100 mL) and the solution was cooled down to -78 °C by a dry ice and Acetone bath under nitrogen atmosphere. Then a solution of sodium methoxide methanol solution, which was prepared by adding

sodium(1 .29 g, 56.1 1 mmol) to dry methanol (ca. 40mL), was added dropwise (over a period of 30 min) into the reaction solution. The reaction solution was allowed to warm up by replacing the dry-ice bath with an ice-water bath before the temperature rose above 0°C. During this time, more and more precipitation was formed in the solution. The reaction solution was further stirred for another 3 h and then the reaction was quenched with 3% hydrochloric acid at 0°C. The solution was filtered to isolate the solid, which was washed with cold methanol- water solution to wash away ionic substances. The resulting yellow solid was further purified via recrystallization from ethanol to give 17 as light yellow crystals. Yield: 84.5 % (4.18 g). 1 H NMR (400 MHz, CDCI3): δ ppm 7.67-7.73 (m, 8H). The synthesis reactions for Examples 13 and 14 are shown below. Example 14

[0080] 2,3-Bis[4-(4,4,5,5-tetramethyl-1 ,3,2-dioxaborolan-2- yl)phenyl]fumaronitrile 19. To a previously degassed 1 ,4-dioxane (27 ml_) solution of bis(4-bromophenyl) fumaronitrile (2.74 g, 7.06 mmol) were added bis(pinacolato) diboron (4.30 g, 16.94 mmol), PdCI ₂ (dppf) (0.287 g, 0.353 mmol), and KOAc (3.46 g, 35.3 mmol), and the mixture was stirred at 100 °C overnight. After the solution was cooled, the dioxane was removed under vacuum, and then CH ₂ CI ₂ and water were added. The resulting mixture was extracted with dichloromethane (100 ml_) twice, and the organic layer was washed with water and brine and then dried over MgS04. The organic solvent was concentrated in reduced pressure to yield a dark-black solid. The crude product 19 was isolated by silica gel column chromatography (using as eluents first 1 :1

methylene/hexane to remove the starting material and then 1 :8 THF/DCM). The resulting yellow solid was further purified via recrystallization from ethanol to give 19 as light yellow crystals. Yield: 76% (2.58 g). 1 H NMR (CDCI ₃ , 400 MHz): δ ppm 7.96 (d, 4H, J = 8.4 Hz), 7.82 (d, 4H, J = 8.4 Hz), 1 .37 (s, 24H).

19

Example 15

[0081 ] Poly{[W, W-bis(2-decyl-tetradecyl)-3,4:9,10-perylenediimide-1 ,7- diyl]-a/i-(2,2'-bithiophene-5,5 ^, -diyl)} PTCDI-2T: To a solution of A/,/V-bis(2- decyl-tetradecyl)-1 ,7-dibromo-3, 4,9, 10-perylene diimide (0.22 mmol, 273.4 mg), 5,5'-bis(trimethylstannyl)-2,2'-bithiophene (0.22 mmol, 1 10.9 mg), and anhydrous chlorobenzene (5 ml_) under nitrogen were added

tris(dibenzylideneacetone)dipalladium(0) (10 μιηοΙ, 9 mg), and

tri(otolyl)phosphine (40 μmol, 12 mg) . The mixture was heated at 120 °C for 48 h with vigorously stirring. After cooling down to room temperature, the reaction mixture was poured into methanol (200 ml_) and HCI (10 ml_) and then stirred for 3 h. The polymer was filtered and subjected to Soxhlet extraction with acetone (24 h), Hexane (24 h) and chloroform (24 h). To the chloroform fraction was added an aqueous solution of sodium diethyldithiocarbamate ( ~ 1 g/100 ml_) and the mixture was heated to 60 ° C with vigorous stirring for 2 h. The mixture was separated and the organic layer was extracted with water for 3 times. The chloroform solution was dried with MgS0 ₄ , concentrated at reduced pressure and precipitated in methanol. The resulting solid was collected by filtration and dried under vacuum to afford the desired polymer (213 mg, 79.8%) as a dark solid. The synthesis reaction for Example 15 is shown below.

PTCDI-2T

Example 16

[0082] Poly{[N,N'-bis(2-decyl-tetradecyl)-3, 4:9,10-perylenediimide-1 ,7- diyl]-alt-(1 ,4- Diethynyltetrafluorobenzene)} PTCDI-AF4A: To a mixture of A/,/V'-bis(2-decyl-tetradecyl)-1 ,7-dibromo-3, 4:9, 10-perylene diimide (0.2 mmol, 244.7 mg), 1 ,4- Diethynyltetrafluorobenzene (0.2 mmol, 39.6 mg), PdCI ₂ (dppf) (0.01 mmol, 7 mg) and Cul (0.01 mmol, 1 .9 mg) under nitrogen was added anhydrous toluene (4 mL) and N,N-Diisopropylamine (2 mL). The mixture was heated at 60 °C for 48 h with vigorously stirring. The polymer was end-capped with pentafluorophenyl by adding lodopentaflurophenyl. After cooling down to room temperature, the reaction mixture was poured into methanol (200 mL) and then stirred for 30 mins. The polymer was filtered and subjected to Soxhlet extraction with acetone (24 h), Hexane (24 h), chloroform (24 h) and

clorobenzene (24 h). The chloroform and chlorobenzene fractions were concentrated and precipitated into methanol, respectively. Following filtration, the purified polymer fractions (15 mg, 3.9%)in chloroform solution and the purified polymer fractions (30 mg, 8%) in chlorobenzene solution were obtained as a deep purple solid. The synthesis reaction for Example 16 is shown below.

Example 17

[0083] NTCDI-BPFN. To a mixture of N A/,A/'-bis(2-decyl-tetradecyl)-2,6- dibromonaphthalene diimide (0.2 mmol, 219.5 mg), 2,3-Bis[4-(4,4,5,5- tetramethyl-1 ,3,2-dioxaborolan-2-yl)phenyl]fumaronitrile (0.2 mmol, 96.4 mg), Aliquat 336(2 drops ) and toluene (5 mL) were added under nitrogen

Pd ₂ (dba) ₃ (10 μιηοΙ, 9 mg),Tri-tert-butyl phosphonium tetrafluoroborate (20 μιηοΙ, 5.8 mg) and a solution of K ₃ P0 ₄ (1 .05 mmol, 223mg) in 0.6 mL deoxygenated water. The mixture was heated at 90 °C for 72 h with vigorously stirring. Phenylboronic acid (27 mg) was added under nitrogen. The mixture was stirred at 90 °C for 10 h. Bromobenzene (0.1 ml) was added under nitrogen. The mixture was stirred at 100°C for 10 h. After cooling down to room temperature, the reaction mixture was dropped into methanol (200 mL) and then stirred for 30 mins. The polymer was filtered and subjected to Soxhiet extraction with acetone (24 h), Hexane (24 h), chloroform (24 h). The chloroform fraction was

concentrated and precipitated into methanol. Following filtration and and drying in the vacuum, the purified polymer (95 mg, 40.7 %) from the chloroform solution was obtained as yellow solid.

NTCDI-BPFN

Example 18

[0084] Poly{[N,N'-bis(2-decyl-tetradecyl) -1 ,4,5,8-naphthalene diimide- 2,6-diyl]-alt-(9-fluorenone -2,7-diyl)} NTCDI-FO. To a mixture of N A/,/V'-bis(2- decyl-tetradecyl)-2,6-dibromonaphthalene diimide (0.2 mmol, 219.5 mg), 2,7- bis(4,4,5,5-tetramethyl-1 ,3,2-dioxaborolanyl)-9-fluorenone (0.2 mmol, 86.4 mg), Aliquat 336(2 drops ) and toluene (5 ml_) were added under nitrogen

Pd ₂ (dba) ₃ (10 μιηοΙ, 9 mg),Tri-tert-butyl phosphonium tetrafluoroborate (20 μmol, 5.8 mg) and a solution of K ₃ P0 ₄ (1 .05 mmol, 223mg) in 0.6 ml_ deoxygenated water. The mixture was heated at 90 °C for 72 h with vigorously stirring.

Phenylboronic acid (27 mg) was added under nitrogen. The mixture was stirred at 90 °C for 10 h. Bromobenzene (0.1 ml) was added under nitrogen. The mixture was stirred at 90°C for 10 h. After cooling down to room temperature, the reaction mixture was dropped into methanol (200 ml_) and then stirred for 30 mins. The polymer was filtered and subjected to Soxhiet extraction with acetone (24 h), Hexane (24 h) and chloroform (24 h). The chloroform fraction was concentrated and precipitated into methanol. Following filtration and drying in the vacuum, the purified polymer (154.8 mg, 69.4 %) solution was obtained as red solid.

NTCDI-FO

Example 19

[0085] The following synthesis reactions and procedures are related to the synthesis of C1 BDPPV polymers.

[0086] Compound 1 was purchased from Sigma Aldrich. Compound 3 was purchased from TCI. Compound 5 was purchased from Lyn (Beijing) Science & Technology Co., Ltd. ( h tt p : //www .ivntech.cn/).

CIBDPPV

[0087] Compound 2. To a suspension of 1 (2.0 g, 8.8 mmol) in anhydrous toluene (100 mL), Ac20 (20 mL) was added. The mixture was stirred at 100 °C for 5 h and then the solvent was removed under reduced pressure. The residue was recrystallized from toluene to give 2 as a gray solid (1 .186 g, 71 %). 1 H NMR (CDCI3, 300 MHz, ppm): δ 7.06 (s, 2H), 3.78 (s, 4H).

[0088] Compound 4, 6 and CIBDOPV were synthesized according to the reference J. Am. Chem. Soc, 2015, 137 (22), pp 6979-6982, the disclosure of which is incorporated herein by reference in its entirety. [0089] CIBDPPV. To a solution of CIBDOPV (0.0663 mmol, 1 19.1 mg), (E)-1 ,2-bis(tributylstannyl)ethene (0.0663 mmol, 40.2 mg), and anhydrous chlorobenzene (4 ml_) under nitrogen were added

tris(dibenzylideneacetone)dipalladium(0) (10 μιηοΙ, 2.4 mg), and tri(o- tolyl)phosphine (40 μιηοΙ, 3.2 mg) . The mixture was heated at 125 °C for 48 h with vigorously stirring. Bromobenzene (0.1 ml) was then added under nitrogen and the reaction mixture was maintained at 125 °C for an additional 12 h. After cooling down to room temperature, the reaction mixture was poured into methanol (200 ml_) and HCI (10 ml_) and then stirred for 3 h. The polymer was filtered and subjected to Soxhlet extraction with acetone (12 h), Hexane (24 h) and chloroform (12 h). The chloroform fraction was concentrated at reduced pressure and precipitated in methanol. The resulting solid was collected by filtration and dried under vacuum to afford the desired polymer (80 mg, 72.5%) as a dark solid.

Example 20

[0090] Procedure for Mixing Polymer with Na-Silica Gel: In the following example, sodium silica gel (Na-SG) particles were used as reducing agents for both polymers, NTCDI2DT-2T (N1 ) and NTCDI-AF4A (N2). Sodium silica gel particles were purchased from sigma Aldrich and ball milled to reduce the particles size. Sodium silica gel particles were then weighed in a glass vial and dissolved in organic solvent, chlorobenzene at 10 mg/mL. NTCDI2DT-2T (N1 ) and NTCDI-AF4A (N2) polymers were weighed in separate glass vials and were dissolved in organic solvent, chlorobenzene at 10 mg/mL. The polymer solution was placed on a hot plate at 80°C while the solution of silica gel was held on a vortex machine (10 minutes) in order to disperse and dissolve the inorganic molecules as much as possible, which are very insoluble. The polymer was blended in the desired concentration with silica gel solution and vigorously stirred on the vortexer (5-10 minutes) before drop-casting.

[0091] Corning, Inc. glass slides were used as a substrate and were cleaned using soap. Then these slides were sonicated using acetone and I PA in ultra-sonic bath for 20 minutes. Gold electrodes of 50 micron thickness were deposited on cleaned glass slides using Edwards thermal evaporation. 2D wells were made using Novec fluorinated polymer on gold electrode glass slides. The final blend of polymer and additives was drop casted onto the 2D well to get 7x7 mm square films. These films were left overnight covered with a petridish to evaporate the solvent slowly and get good packing of the film. Next day, samples were placed on a hot plate by slowly ramping the temperature from 50°C to 150°C. The sample was maintained at 150°C for 2-3 hrs and then the

temperature was ramped down to 80°C, mostly to remove the residual solvent. The result was a 7*7 mm square film with 1 -2 micrometer thickness (from about 75 microliters of starting solution), lying over two thin metal electrodes (0.2-0.3 cm across and 1 cm wide) having a channel gap (0.3-0.5 cm across and 1 cm wide). All the above-mentioned processes of this example were carried out in a glovebox.

[0092] Seebeck co-efficient and electrical conductivity measurements of cured polymeric films were done in air. Measurement techniques used in the above examples will now be described. The Seebeck coefficient S was measured using a custom made lab setup. The polymer sample was placed across two stage mounted peltier heater/cooler tiles electrically connected to the power supply with one electrode of the sample over each tile. Peltiers were then controlled to heat or cool on each side. Thermal EMF (V) and the temperature difference (7) were measured simultaneously by probing the pair of electrodes with a source meter and thermocouples. An optimal thin-film electrode geometry (being a set of narrow, parallel strips, and no semiconductor material outside of the inter electrode region or space between electrodes), which minimizes external conduction pathways was used to minimize signal-to- noise and overcome the increased device impedance associated with this otherwise preferred electrode arrangement. Thermal paste is used to minimize thermal contact resistance between the bottom of our substrates and Peltier devices. This system is enclosed in a thermally insulated case to reduce the

measurement error from noise. The Seebeck coefficient is measured as

where V is Thermal EMF and T is the associated temperature difference as described above in this paragraph.

[0093] In order to decrease the error in measurements, for each value of

ΔΤ, 500 measurements of AV were performed and then the average of these AV values was calculated. At six different values of ΔΤ (OK, 2K, 4K, 6K, 8K, and 10K) voltage difference was measured and the slope of AV versus ΔΤ give the Seebeck co-efficient. The setup was calibrated using tellurium . [0094] Power factor (α ² σ) was calculated by multiplying the square of the Seebeck coefficient with electrical conductivity. The Seebeck coefficient and electrical conductivity were measured at room temperature only.

[0095] Na-SG solid particles were added to NTCDI2DT-2T (N1 ) and NTCDI-AF4A (N2) polymers in the range of 0% to 75wt%. Na-SG were dispersed in the host matrix. All the thermoelectric properties of this example were measured in open air at room temperature.

[0096] The results are shown in FIGS. 2, 3 and 4. FIG. 2 shows electrical conductivity of undoped and Na-SG particle doped N1 and N2 polymers at varying weight percentages. FIG. 3 shows Seebeck co-efficient of undoped and Na-SG particle doped N1 and N2 polymers at varying weight percentages. FIG. 4 shows the Power factor of undoped and Na-SG particles doped N1 and N2 polymers at varying weight percentages.

[0097] As shown in FIG. 2 electrical conductivity of pure polymer N1 and N2 was in the range of 10 ^"6 S/cm. With the addition of 75 wt% of Na-SG particles, conductivity of N1 and N2 polymer composite films increased by two to three orders of magnitude. NTCDI2DT-2T with 75wt% Na-SG particles had electrical conductivity in the range of 2X10 ^"3 S/cm. The improvement in electrical conductivity confirmed that sodium in Na-SG particles reduced the polymers N1 and N2 respectively. Reduction of polymers introduced free charge carriers (electrons) into the LUMO of the N1 and N2 polymers respectively to increase their carrier density and electrical conductivity. At 75 wt% Na-SG particles, the volume % of Na-SG particles and polymer is about 80% and 20% respectively. Insulating Na-SG particles block the path of charge carries in polymer. Only 20% of the volume is occupied by conducting polymer, which contributes to the higher conductivity. It is believed that if the particle size of Na-SG is improved to the nanometer range, the charge carriers can more easily move without getting affected by insulating silica gel, and the conductivity can be improved to 2x10 ^{" 2} S/cm.

[0098] FIG. 3 shows Seebeck co-efficient vs. weight percentage of Na-SG particles. With 25wt% of Na-SG particles the Seebeck coefficient of the polymer composite films increased about 5 times as compared to pure polymers N1 and N2 respectively. Similarly, with addition of 50wt% of Na-SG particles, the

Seebeck coefficient of polymer composite films increased about 3 times as compared to pure polymers N1 and N2 respectively. Polymer composite films with 75wt% of Na-SG particles have a much lower Seebeck co-efficient as compare to 25wt% and 50wt% of Na-SG. However, the electrical conductiivty was higher for these films. For typical thermoelectric materials, if the elecrtical conductivity is high then the Seebeck co-efficient is relatively low.

[0099] FIG. 4 shows power factor vs. weight percentage of Na-SG particles. With 50wt% of Na-SG particles, the power factor of the polymer composite films was highest, nearly 1 μW/m-k ² .

[00100] Because conductivity and Seebeck are both higher in the 50% sample than in the 0% sample, it is possible that the Seebeck values achieved herein may be enhanced due to energy filtering mechanisms, where hot carriers move more easily past particles than cold carriers. While the particles of the present disclosure were not designed for this purpose, it may happen with particles in general. [00101] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein.

[00102] While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. In addition, while a particular feature of the present teachings may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular function. Furthermore, to the extent that the terms "including," "includes," "having," "has," "with," or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term "comprising." Further, in the discussion and claims herein, the term "about" indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, "exemplary" indicates the description is used as an example, rather than implying that it is an ideal.

[00103] It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompasses by the following claims.