CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is based on and claims priority to U.S. Provisional Application No. 62/532,693, filed July 14, 2017, entitled "Method for synthesizing electrochromic polymer thin films." The entire contents of the above-referenced application are all incorporated herein by reference.

TECHNICAL FIELD

[0002] The disclosure relates generally to electrochromic polymer thin films, and more particularly, to black-to-transmissive electrochromic polymer thin films with a high optical contrast and a fast switch, and methods of using and making the same.

BACKGROUND

[0003] Electrochromism refers to a reversible optical spectrum change upon an electron transfer reaction induced via an application of voltage. Recently, electrochromic (EC) materials play an increasingly vital role in both academic and practical areas since it achieves a reversible and highly stable variation of transmissive/absorptive spectra and tunable colors between doped and undoped states, and hence possesses a great potential to be used in smart windows mirror, sunglasses, digital signage and displays, as well as electronic paper

[0004] Among various EC material candidates, inorganic materials such as (transition) metal oxides and their complexes are the most widely exploited color-changing materials due to broad polaron absorption and high photochemistry, nevertheless, always limited by a slow respond time and low coloration efficiency. A polaron is a quasiparticle used to understand interactions between electrons and atoms in a solid material. A photochemistry refers to a chemical reaction caused by absorption of light. Alternatively, conjugated polymers have been recognized as desired materials in all sorts of electrochromic devices (ECDs) for their tunable colors, high optical contrast, easy processability, and long-term stability. Currently, many investigations have been devoted into the various saturated colored-to-transmissive polymeric ECDs from their neutral states to doped states. Especially, black-to-transmissive electrochromic polymers (ECPs) is gradually becoming a hot spot as it is signified to be a promising material for privacy glass and smart windows. However, there still remains a challenge due to complexity and incompleteness of absorption over the whole visible spectrum in the neutral state, followed by bleaching out in a fully oxidized state.

[0005] Up to now, significant efforts have been devoted to design and obtain a desired black color and a full spectrum, and various materials and strategies are emerging. As mentioned, although metal oxides and their complex, such as porous NiO, Co-based polymer, CuCh, IrCh have been extensively investigated and can be served as the black-to-transmissive

electrochromes, they show inferior EC performances (low coloration efficiency and slow color change) compared with organic polymer materials.

[0006] Organic black-to-transmissive EC materials include (1) individual copolymers absorbing the entire visible spectrum, and (2) complementary compositions based on "color- mixing" theory to achieve a complete spectrum and a black-to-transmissive EC display. When two or more different monomers unite together to polymerize, their result is called a copolymer and its process is called copolymerization. Various sorts of black-to-transmissive ECDs are reported with the second method by blending multicolored compounds or constructing complementary multilayers. Consequently cathodically coloring layer EC materials can potentially complement an anodically coloring electrode to form a panchromatic absorption spectrum within the visible spectrum. However, the resulting colors obtained by this method show a relatively low optical contrast, complex process, or pseudo-color phenomenon. Also, performance and manipulation limitations seriously limit the applications in a narrow range.

[0007] Initiated by others works on the design and synthesis of conjugated ECPs with neutral state colors of blue, green or black, band gaps of these materials must be lower than 1.75 eV. To construct a low-band gap system, a "donor-acceptor" (D-A) strategy via alternating electron- donating and electron-accepting (i.e., electron-rich and electron-deficienr) units, is verified as an effective solution and has been widely employed to synthesize individual copolymers.

Nevertheless, the band gap is not the only factor in determination of a color state. A color state is a comprehensive result of wavelengths and intensities with different optical transitions. More importantly, there are multiple absorption spectra with various breadths existing in the D-A copolymers structure. The first neutral-state black-to-transmissive polymeric electrochrome was proposed and developed by Reynolds group (P. M. Beaujuge, S. Ellinger, J. R. Reynolds, the donor-acceptor approach allows a black-to-transmissive switching polymeric electrochrome, Nat. iter. 2008, 7, 795-799). Then they made further improvements and investigated several kinds copolymers in lower fabrication and processing costs, as well as good performance, exhibitin 5t switching responds, high optical contrast. Nevertheless, additional improvements are still mired for more uniform and broad absorbance across the entire visible spectrum to meet need the applications.

SUMMARY

D08] This disclosure presents individual black-to-transmissive electrochromic copolymers lich absorb over the entire visible spectrum, and methods of preparing the copolymers as well their uses in ECDs.

D09] One aspect of the present disclosure is directed to a black-to-transmissive

;ctrochromic polymer having more uniform and broad absorbance across the entire visible ectrum. In some embodiments, the black-to-transmissive electrochromic polymer is of irmula (I):

each of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ is independently hydrogen, optionally substituted C1-C30 alkyl, optionally substituted C2-C30 alkenyl, optionally substituted C2-C30 alkynyl, optionally substituted C2-C30 alkyl carbonyl, optionally substituted Ci C30 alkoxy, optionally substituted C3-C30 alkoxyalkyl, optionally substituted C2-C30 alkoxycarbonyl, optionally substituted C4-C30 alkoxycarbonylalkyl, optionally substituted C1-C30 aminylcarbonyl, optionally substituted C4-C30 aminylalkyl, optionally substituted C1-C30 alkylaminyl, optionally substituted C1-C30 alkylsulfony optionally substituted C3-C30 alkyl sulfonylalkyl, optionally substituted C ₆ -Ci8 aryl, optionally substituted C3-C15 cycloalkyl, optionally substituted C3-C30

cycloalkylaminyl, optionally substituted C5-C30 cycloalkylalkylaminyl, optionally substituted C5-C30 cycloalkylalkyl, optionally substituted C5-C30 cycloalkylalkyloxy, optionally substituted C1-C12 heterocyclyl, optionally substituted C1-C12

heterocyclyloxy, optionally substituted C3-C30 heterocyclylalkyloxy, optionally substituted C1-C30 heterocyclylalkyloxy, optionally substituted C1-C30

heterocyclylaminyl, optionally substituted C5-C30 heterocyclylalkylaminyl, optionall; substituted C2-C12 heterocyclylcarbonyl, optionally substituted C3-C30 heterocyclylalkyl, optionally substituted C1-C13 heteroaryl, or optionally substituted

C3-C30 heteroarylalkyl;

each r, s and t is independently an integer of equal to or greater than 1;

n is an integer of equal to or greater than 1; represents connection to the rest of the molecule; and

B A C

average ratio of I I , I I , and I 1 in the polymer is x:y:z, wherein x ran from about 0.2 to about 0.6, y ranges from about 1.2 to about 1.45, and z ranges frorr about 0.2 to about 0.45, and x+y+z =2.

D10] Another aspect of the present disclosure is directed to a black-to-transmissive

;ctrochromic polymer. The synthesized black polymer may absorb across the entire visible ectrum and realize an obvious color change from black (e.g., L* = 49.2, a* = -10-5, b* = - ~5, such as a* = 3.6, b* = -7.7) to transmissive (e.g., L* = 85, a* = -10-5, b* = -10-5, such a: = -4.6, b* = -5.8) with an applied voltage of 0-1.2 V. An optical contrast as high as nearly 70 may be achieved within 10 seconds in electrochromic thin films made of the black polymer.

Oil] Another aspect of the present disclosure is directed to a method for synthesizing a ick-to-transmissive electrochromic polymer via controlling monomer feed ratios in a direct Ration polymerization. In some embodiments, to synthesize the black polymer, with 1.0 uivalent of monomer 1, the feed ratios of monomers 2, 3 and 4 may range from 0.2 - 0.6, 0.2 15, 0.2 - 0.35, respectively, wherein monomers 1, 2, 3 and 4 are as described herein.

012] Another aspect of the present disclosure is directed to electrochromic thin films made the black polymer, and a black-to-transmissive ECD based on the as-prepared electrochromic ms may be designed using a transparent indium tin oxide (ITO) as a counter electrode for arge storage. The ECD may display high contrasts for 43.6%, switching from a saturated blaa tte (L* = 37.8, a* = -5-0, b* = -10-0, such as a* = 2.5, b* = -6.4) to a transmissive state (L* = .6, a* = -5-0, b* = -5-0, such as a* = -8.0, b* = -6.5).

013] It is to be understood that the foregoing general description and the following detailed scription are exemplary and explanatory only, and are not restrictive of the disclosure, as timed. BRIEF DESCRIPTION OF THE DRAWINGS

014] The accompanying drawings, which constitute a part of this disclosure, illustrate ^eral non-limiting embodiments and, together with the description, serve to explain the iclosed principles.

015] FIG. 1 is a graphical diagram illustrating a reaction scheme for a synthesis of black lymers, consistent with exemplary embodiments of the present disclosure.

016] FIG. 2A is a graph illustrating measurement results of solution absorption of black lymers in chloroform; FIG. 2B is a graph illustrating measurement results of normalized film sorption of the black polymers, consistent with exemplary embodiments of the present ^closure.

017] FIG. 3 A is a graph illustrating measurement results of cyclic voltammograms of lymer P4; FIG. 3B is a graph illustrating measurement results of spectroelectrochemistry of lymer P4, FIG. 3C a graph illustrating lightness (L*) as a function of applied potential for in-coated P4 film, and FIG. 3D is a graph illustrating a summary of the square wave potential :p chronoabsorptometry of a P4 spin-coated ITO; consistent with exemplary embodiments of i present disclosure.

018] FIGs. 4A - D are graphs illustrating square-wave potential-step chronoabsorptometry PI, P2, P3 and P4 spin-coated ITOs respectively, consistent with exemplary embodiments of i present disclosure.

019] FIGs. 5A - B are graphs illustrating A transmittance and B current change of polymer in 10 s interval steps between 0 and 1.2 V, consistent with exemplary embodiments of the ssent disclosure.

D20] FIG. 6 is a graph illustrating measurement results of transmittance spectra of an ECD, nsistent with exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

021] Reference will now be made in detail to exemplary embodiments, examples of which i illustrated in the accompanying drawings. The following description refers to the companying drawings in which the same numbers in different drawings represent the same or nilar elements unless otherwise represented. The implementations set forth in the following scription of exemplary embodiments consistent with the present disclosure do not represent al plementations consistent with the disclosure. Instead, they are merely examples of systems d methods consistent with aspects related to the disclosure.

022] As used herein, the term "comprising" is intended to mean that the compositions and jthods include the recited elements, but not excluding others. "Consisting essentially of whe ed to define compositions and methods, shall mean excluding other elements of any essential Snificance to the combination. For example, a composition consisting essentially of the ;ments as defined herein would not exclude other elements that do not materially affect the sic and novel characteristic(s) of the claimed invention. "Consisting of shall mean excluding Dre than trace amount of other ingredients and substantial method steps recited. Embodiments fined by each of these transition terms are within the scope of this invention.

023] Numeric ranges are also inclusive of the numbers defining the range. Additionally, i singular forms "a", "an" and "the" include plural referents unless the context clearly dictates lerwise.

024] Reference throughout this specification to "one embodiment," "an embodiment" or Dme embodiments" means that a particular feature, structure or characteristic described in nnection with the embodiment is included in at least one embodiment of the present invention IUS, the appearances of the phrases "in one embodiment," "in an embodiment" or "in some lbodiments" in various places throughout this specification are not necessarily all referring to i same embodiment or embodiments, but may be in some instances. Furthermore, the rticular features, structures, or characteristics may be combined in any suitable manner in one more embodiments.

025] The term "about" when used before a numerical value indicates that the value may ry within reasonable range, such as ± 10%, ± 5%, and ± 1%.

026] Unless defined otherwise, all technical and scientific terms used herein have the sarrn waning as is commonly understood by one of skill in the art to which this invention belongs, ir instance, "amino" refers to the -NFh radical; "hydroxy" or "hydroxyl" refers to the OH iical; "thioxo" refers to the =S substituent, etc. 027] Alkyl" refers to a straight or branched hydrocarbon chain radical consisting solely c rbon (C) and hydrogen (H) atoms, which is saturated or unsaturated (i.e., contains one or mors uble and/or triple bonds), having from 1 to 30 carbon atoms (C1-C30 alkyl), and which is ached to the rest of the molecule by a single bond, e.g., methyl, ethyl, ^-propyl, 1-methylethy] o-propyl), «-butyl, «-pentyl, 1,1-dimethylethyl (t-butyl), 3-methylhexyl, 2-methylhexyl, lenyl, prop-l-enyl, but-l-enyl, pent-l-enyl, penta-l,4-dienyl, ethynyl, propynyl, butynyl, ntynyl, hexynyl, and the like. Unless stated otherwise specifically in the specification, an alky Dup may be optionally substituted.

028] "Alkylene" or "alkylene chain" refers to a straight or branched divalent hydrocarbon ain linking the rest of the molecule to a radical group, consisting solely of carbon and drogen, which is saturated or unsaturated (i.e., contains one or more double and/or triple nds), and having from 2 to 30 carbon atoms (C2-C30 alkylene), e.g., methylene, ethylene, Dpylene, «-butylene, ethenylene, propenylene, «-butenylene, propynylene, «-butynylene, and ϊ like. The alkylene chain is attached to the rest of the molecule through a single or double nd and to the radical group through a single or double bond. The points of attachment of the xylene chain to the rest of the molecule and to the radical group can be through one carbon or y two carbons within the chain. Unless stated otherwise specifically in the specification, an xylene chain may be optionally substituted.

029] "Alkylcarbonyl" refers to a radical of the formula -(C=0)R ^a where R ^a is a C1-C30yl radical as defined above. Unless stated otherwise specifically in the specification, anylcarbonyl group may be optionally substituted.

D30] "Alkoxy" refers to a radical of the formula -OR ^a where R ^a is a C1-C30 alkyl radical a; fined above. A "haloalkoxy" is an alkoxy group as defined above, wherein at least one carbon drogen bond is replaced with a carbon-halogen bond. Unless stated otherwise specifically in i specification, an alkoxy or haloalkoxy group may be optionally substituted.

031] " Alkoxyalkyl" refers to a radical of the formula -R ^b OR ^a where R ^a is a C1-C30 alkyl iical as defined above, and R ^b is a C2-C30 alkylene radical as defined above. A

aloalkoxyalkyl" group is an alkoxyalkyl, wherein at least one carbon-hydrogen bond is placed with a carbon-halogen bond. Unless stated otherwise specifically in the specification, aoxyalkyl or haloalkoxyalkyl group may be optionally substituted. 032] "Alkoxycarbonyl" refers to a radical of the formula -(C=0)OR ^a where R ^a is a Ci-C ₃ cyl radical as defined above. Unless stated otherwise specifically in the specification, an xycarbonyl group may be optionally substituted.

033] "Alkoxycarbonylalkyl" refers to a radical of the formula -R ^b (C=0)OR ^a where R ^a is ί -C ₃ o alkyl radical as defined above, and R ^b is a C ₂ -C ₃ o alkylene as defined above. Unless Lted otherwise specifically in the specification, an alkoxycarbonylalkyl group may be tionally substituted.

034] "Aminylcarbonyl" refers to a radical of the formula -(C=0)N(R ^a ) ₂ , where each R ^a is iependently H or a Ci-C ₃ o alkyl group as defined above. Unless stated otherwise specifically the specification, an aminylcarbonyl group may be optionally substituted.

035] "Aminylalkyl" refers to a radical of the formula -R ^a N(R ^b ) ₂ where R ^a is a C ₂ -C ₃ o xylene as defined above, and each R ^b is independently a Ci-C ₃ o alkyl radical as defined above, lless stated otherwise specifically in the specification, an aminylalky group may be optionally bstituted.

036] "Alkylaminyl" refers to a radical of the formula - HR ^a or - R ^a R ^a where each R ^a is iependently a Ci-C ₃ o alkyl radical as defined above, and R ^a is a Ci-C ₃ o alky radical as defined ove. Unless stated otherwise specifically in the specification, an aminylalky group may be tionally substituted.

037] "Alkyl sulfonyl" refers to a radical of the formula -S(0) ₂ R ^a where R ^a is a Ci-C ₃ o alky iical as defined above. Unless stated otherwise specifically in the specification, an

ylsulfonyl group may be optionally substituted.

038] "Alkylsulfonylalkyl" refers to a radical of the formula -R ^b S(0) ₂ R ^a where R ^a is a Ci- o alkyl radical as defined above, and R ^b is a C ₂ -C ₃ o alkylene radical as defined above. Unless Lted otherwise specifically in the specification, an alkylsulfonylalkyl group may be optionally bstituted.

039] "Cyanoalkyl" is a Ci-C ₃ o alkyl group as defined above, wherein at least one carbon- drogen bond is replaced with a carbon-cyano bond. Unless stated otherwise specifically in tfr ecification, a cyanoalkyl group may be optionally substituted. D40] "Hydroxylalkyl" refers to a C1-C30 alkyl radical as defined above, which has been bstituted by one or more hydroxyl groups. Unless stated otherwise specifically in the ecification, a hydroxylalkyl group may be optionally substituted.

041] "Aryl" refers to a hydrocarbon ring system radical comprising hydrogen, 6 to 18 rbon atoms and at least one aromatic ring. For purposes of this invention, the aryl radical may a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or idged ring systems. Aryl radicals include, but are not limited to, aryl radicals derived from enyl, naphthyl, anthryl, etc. Unless stated otherwise specifically in the specification, the term ryl" is meant to include aryl radicals that are optionally substituted.

042] "Conjugated polymer" refers to a polymer having alternating single and double (or pie) carbon-carbon bonds along at least a portion of the polymer backbone.

043] "Cycloalkyl" or "carbocyclic ring" refers to a stable non-aromatic monocyclic or lycyclic hydrocarbon radical consisting solely of carbon and hydrogen atoms, which may ;lude fused or bridged ring systems, having from 3 to 15 carbon atoms, and which is saturated unsaturated and attached to the rest of the molecule by a single bond. Monocyclic radicals ly include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cloheptyl, and cyclooctyl. Polycyclic radicals may include, but are not limited to, adamantyl, rbornyl, decalinyl, 7,7-dimethyl-bicyclo[2.2.1]heptanyl, and the like. Unless otherwise stated ecifically in the specification, a cycloalkyl group may be optionally substituted.

044] "Cycloalkylaminyl" refers to a radical of the formula - R ^a R ^c where R ^a is, iependently, H or a C1-C30 alkyl radical as defined above, and R ^c is a C3-C15 cycloalkyl radica defined above. Unless stated otherwise specifically in the specification, an aminylalky group ly be optionally substituted.

045] "Cycloalkylalkylaminyl" refers to a radical of the formula - R ^a R ^b -R ^c where R ^a is iependently H or a C1-C30 alkyl radical as defined above, R ^b is a C2-C30 alkylene radical as fined above, and R ^c is a C3-C15 cycloalkyl radical as defined above. Unless stated otherwise ecifically in the specification, a cycloalkylalkylaminyl group may be optionally substituted.

046] "Cycloalkylalkyl" refers to a radical of the formula -R ^b R ^c where R ^b is a C2-C30 xylene chain as defined above, and R ^c is a C3-C15 cycloalkyl radical as defined above. Unless Lted otherwise specifically in the specification, a cycloalkylalkyl group may be optionally bstituted.

047] "Cycloalkylalkyloxy" refers to a radical of the formula -OR ^b R ^c where R ^b is a C2-C30 xylene chain as defined above, and R ^c is a C3-C15 cycloalkyl radical as defined above. Unless Lted otherwise specifically in the specification, a cycloalkylalkyloxy group may be optionally bstituted.

048] "Fused" refers to any ring structure described herein which is fused to an existing rin ucture in the compounds of the invention. When the fused ring is a heterocyclyl ring or a teroaryl ring, any carbon atom on the existing ring structure which becomes part of the fused terocyclyl ring or the fused heteroaryl ring may be replaced with a nitrogen atom.

049] "Halo" or "halogen" refers to bromo, chloro, fluoro or iodo.

D50] "Haloalkyl" refers to a C1-C30 alkyl radical as defined above, that is substituted by e or more halo radicals as defined above, e.g., trifluoromethyl, difluoromethyl,

chlorom ethyl, 2,2,2-trifluoroethyl, 1,2-difluoroethyl, 3-bromo-2-fluoropropyl,

.-dibromoethyl, and the like. Unless stated otherwise specifically in the specification, a loalkyl group may be optionally substituted.

051] "Heterocyclyl" or "heterocyclic ring" refers to a stable 3- to 18-membered n-aromatic ring radical which consists of 2 to 12 carbon atoms and from 1 to 6 heteroatoms lected from the group consisting of nitrogen, oxygen and sulfur. Unless stated otherwise ecifically in the specification, the heterocyclyl radical may be a monocyclic, bicyclic, tricyclic tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, rbon or sulfur atoms in the heterocyclyl radical may be optionally oxidized; the nitrogen atom ly be optionally quaternized; and the heterocyclyl radical may be partially or fully saturated. :amples of such heterocyclyl radicals may include, but are not limited to, dioxolanyl, enyl[l,3]dithianyl, decahydroisoquinolyl, imidazolinyl, imidazolidinyl, isothiazolidinyl, )xazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, 2-oxopiperazinyl,

Dxopiperidinyl, 2-oxopyrrolidinyl, oxazolidinyl, piperidinyl, piperazinyl, 4-piperidonyl, rrolidinyl, pyrazolidinyl, quinuclidinyl, thiazolidinyl, tetrahydrofuryl, trithianyl,

rahydropyranyl, thiomorpholinyl, thiamorpholinyl, 1-oxo-thiomorpholinyl, and l-dioxo-thiomorpholinyl. Unless stated otherwise specifically in the specification, a terocyclyl group may be optionally substituted.

052] "Heterocyclyloxy" refers to a radical of the formula -OR ^d , wherein R ^d is a C1-C12 terocyclyl radical as defined above. Unless stated otherwise specifically in the specification, a terocyclyloxy group may be optionally substituted.

053] "Heterocyclylalkyloxy" refers to a radical of the formula -OR ^b R ^d where R ^b is a C2-

0 alkylene chain as defined above, and R ^d is a C1-C12 heterocyclyl radical as defined above, lless stated otherwise specifically in the specification, a heterocyclylalkyloxy group may be tionally substituted.

054] "Heterocyclylaminyl" refers to a radical of the formula -N(R ^a ) ₂ R ^d where R ^a is iependently H or a C1-C30 alkyl radical as defined above, and R ^d is a C1-C12 heterocyclyl iical as defined above. Unless stated otherwise specifically in the specification, a

terocyclylaminyl group may be optionally substituted.

055] "Heterocyclylalkylaminyl" refers to a radical of the formula - R ^a R ^b -R ^d where R ^a is or a C1-C30 alkyl radical as defined above, R ^b is a C2-C30 alkylene radical as defined above, d R ^d is a C1-C12 heterocyclyl radical as defined above. Unless stated otherwise specifically in

1 specification, a cycloalkylalkylaminyl group may be optionally substituted.

056] "Heterocyclylcarbonyl" refers to a radical of the formula -C(=0)R ^d where R ^d is a Ci

2 heterocyclyl radical as defined above. Unless stated otherwise specifically in the

ecification, a heterocyclycarbonyl group may be optionally substituted.

057] "Heterocyclylalkyl" refers to a radical of the formula -R ^b R ^d where R ^b is a C2-C30 xylene chain as defined above, and R ^d is a C1-C12 heterocyclyl radical as defined above. Unles ited otherwise specifically in the specification, a heterocyclylalkyl group may be optionally bstituted.

058] "Heteroaryl" refers to a 5 to 14 membered ring system radical comprising hydrogen )ms, 1 to 13 carbon atoms, 1 to 6 heteroatoms selected from the group consisting of nitrogen, ygen and sulfur, and at least one aromatic ring. For purposes of this invention, the heteroaryl iical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include sed or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heteroaryl radical iy be optionally oxidized; the nitrogen atom may be optionally quaternized. Examples include t are not limited to, azepinyl, acridinyl, benzimidazolyl, benzothiazolyl, benzindolyl, nzodioxolyl, benzofuranyl, benzooxazolyl, benzothiazolyl, benzothiadiazolyl,

nzo[£][l,4]dioxepinyl, 1,4-benzodioxanyl, benzonaphthofuranyl, benzoxazolyl,

nzodioxolyl, benzodioxinyl, benzopyranyl, benzopyranonyl, benzofuranyl, benzofuranonyl, nzothienyl (benzothiophenyl), benzotriazolyl, benzo[4,6]imidazo[l,2-a]pyridinyl, carbazolyl, inolinyl, dibenzofuranyl, dibenzothiophenyl, furanyl, furanonyl, isothiazolyl, imidazolyl, iazolyl, indolyl, indazolyl, isoindolyl, indolinyl, isoindolinyl, isoquinolyl, indolizinyl, >xazolyl, naphthyridinyl, oxadiazolyl, 2-oxoazepinyl, oxazolyl, oxiranyl, 1-oxidopyridinyl, Dxidopyrimidinyl, 1-oxidopyrazinyl, 1-oxidopyridazinyl, 1 -phenyl- lH-pyrrolyl, phenazinyl, enothiazinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyridinyl, razinyl, pyrimidinyl, pyridazinyl, quinazolinyl, quinoxalinyl, quinolinyl, quinuclidinyl, >quinolinyl, tetrahydroquinolinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, triazinyl, and ophenyl (i.e. thienyl). Unless stated otherwise specifically in the specification, a heteroaiyl Dup may be optionally substituted.

059] "Heteroarylalkyl" refers to a radical of the formula -R ^b R ^e where R ^b is a C2-C30 xylene chain as defined above, and R ^e is a C1-C13 heteroaiyl radical as defined above. Unless Lted otherwise specifically in the specification, a heteroarylalkyl group may be optionally bstituted.

D60] The term "substituted" used herein means any of the above groups (e.g., alkyl, xylene, alkylcarbonyl, alkoxy, alkoxyalkyl, haloalkoxyalkyl, alkoxycarbonyl,

xycarbonylalkyl, aminylcarbonyl, aminylalkyl, alkylaminyl, alkylsulfonyl,

ylsulfonylalkyl, cyanoalkyl, hydroxylalkyl, aryl, cycloalkyl, cycloalkylalkyl, cycloalkyloxy, cloalkylaminyl, cycloalkylalkylaminyl, cycloalkylalkyloxy, haloalkyl, heterocyclyl, terocyclyloxy, heterocyclylalkyloxy, heterocyclylaminyl, heterocyclylalkylaminyl, terocyclylcarbonyl, heterocyclylalkyl, heteroaiyl and/or heteroarylalkyl)wherein at least one drogen atom is replaced by a bond to a non-hydrogen atoms such as, but not limited to: a logen atom such as F, CI, Br, and I; an oxygen atom in groups such as hydroxyl groups, alkox Dups, and ester groups; a sulfur atom in groups such as thiol groups, thioalkyl groups, sulfone Dups, sulfonyl groups, and sulfoxide groups; a nitrogen atom in groups such as amines, amide; famines, dialkylamines, arylamines, alkylarylamines, diarylamines, N-oxides, imides, and amines; a silicon atom in groups such as trialkylsilyl groups, dialkylarylsilyl groups,yldiarylsilyl groups, and triarylsilyl groups; and other heteroatoms in various other groups, ubstituted" also means any of the above groups in which one or more hydrogen atoms are placed by a higher-order bond (e.g., a double- or triple-bond) to a heteroatom such as oxygen oxo, carbonyl, carboxyl, and ester groups; and nitrogen in groups such as imines, oximes, drazones, and nitriles. For example, "substituted" includes any of the above groups in which e or more hydrogen atoms are replaced with - R¾ ^h , - R C(=0)R ^h , -NR¾(=0)NR¾ ^h , - C(=0)OR ^h , - R ^g S0 ₂ R ^h , -OC(=0) R ^g R ^h , -OR ^g , -SR ^g , -SOR ^g , -S0 ₂ R ^g , -OS0 ₂ R ^g , - ) ₂ OR ^g , =NS0 ₂ R , and -SCh R^A "Substituted also means any of the above groups in which e or more hydrogen atoms are replaced with -C(=0)R , -C(=0)OR , -C(=0) R R ^h , - ¾S0 ₂ R , In the foregoing, R ^g and R ^h are the same or different and iependently hydrogen, alkyl, alkoxy, alkylaminyl, thioalkyl, aryl, aralkyl, cycloalkyl, cloalkylalkyl, haloalkyl, heterocyclyl, N-heterocyclyl, heterocyclylalkyl, heteroaryl, N- teroaryl and/or heteroarylalkyl. "Substituted" further means any of the above groups in which e or more hydrogen atoms are replaced by a bond to an amino, alkylaminyl, cyano, hydroxyl, ino, nitro, oxo, thioxo, halo, alkyl, alkoxy, alkylaminyl, thioalkyl, aryl, aralkyl, cycloalkyl, cloalkylalkyl, haloalkyl, heterocyclyl, N-heterocyclyl, heterocyclylalkyl, heteroaryl, N- teroaryl and/or heteroarylalkyl group. In addition, each of the foregoing substituents may also optionally substituted with one or more of the above substituents.

061] "Optional" or "optionally" means that the subsequently described event of

cumstances may or may not occur, and that the description includes instances where said ent or circumstance occurs and instances in which it does not. For example, "optionally bstituted aryl" means that the aryl radical may or may not be substituted and that the scription includes both substituted aryl radicals and aryl radicals having no substitution.

062] As used herein, the term "contacting" refers to bringing two or more chemical nlecules to close proximity so that a chemical reaction between the two or more chemical nlecules can occur. For example, contacting may comprise mixing and optionally continuously xing the chemicals. Contacting may be done by fully or partially dissolving or suspending tw< more chemicals in one or more solvents, mixing of a chemical in a solvent with another emical in solid and/or gas phase or being attached on a solid support, such as a resin, or mixin o or more chemicals in gas or solid phase and/or on a solid support, that are generally known those skilled in the art.

063] In this disclosure, we present black-to-transmissive electrochromic polymers sreinafter also referred to as "black polymers") that absorb across the entire visible spectrum d realize an obvious color change from black to transmissive with an applied voltage. Also Dvided is a method for synthesizing a black polymer via controlling monomer feed ratios in a 'ect arylation polymerization. The direct arylation polymerization method features formations C-C bonds between halogenated arenes and simple arenes with active C-H bonds, thereby cumventing the preparation of organometallic derivatives and decreasing overall production st of conjugated polymers.

064] In some embodiments, provided is a black-to-transmissive electrochromic polymer of irmula (I):

or a combination thereof;

each of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ is independently hydrogen, optionally substituted C1-C30 alkyl, optionally substituted C2-C30 alkenyl, optionally substituted C2-C30 alkynyl, optionally substituted C2-C30 alkyl carbonyl, optionally substituted Ci C30 alkoxy, optionally substituted C3-C30 alkoxyalkyl, optionally substituted C2-C30 alkoxycarbonyl, optionally substituted C4-C30 alkoxycarbonylalkyl, optionally substituted C1-C30 aminylcarbonyl, optionally substituted C4-C30 aminylalkyl, optionally substituted C1-C30 alkylaminyl, optionally substituted C1-C30 alkylsulfony optionally substituted C3-C30 alkylsulfonylalkyl, optionally substituted C ₆ -Ci8 aryl, optionally substituted C3-C15 cycloalkyl, optionally substituted C3-C30

cycloalkylaminyl, optionally substituted C5-C30 cycloalkylalkylaminyl, optionally substituted C5-C30 cycloalkylalkyl, optionally substituted C5-C30 cycloalkylalkyloxy, optionally substituted C1-C12 heterocyclyl, optionally substituted C1-C12 heterocyclyloxy, optionally substituted C3-C30 heterocyclylalkyloxy, optionally substituted C1-C30 heterocyclylalkyloxy, optionally substituted C1-C30

heterocyclylaminyl, optionally substituted C5-C30 heterocyclylalkylaminyl, optionall; substituted C2-C12 heterocyclylcarbonyl, optionally substituted C3-C30

heterocyclylalkyl, optionally substituted C1-C13 heteroaryl, or optionally substituted C3-C30 heteroarylalkyl;

each r, s and t is independently an integer of equal to or greater than 1;

n is an integer of equal to or greater than 1;

^ represents connection to the rest of the molecule; and

B C

the average ratio of I I , I I , and I 1 in the polymer is x:y:z, wherein x ran

from about 0.2 to about 0.6, y ranges from about 1.2 to about 1.45, and z ranges fron about 0.2 to about 0.45, and x+y+z is about 2.

065] In some embodiments, x ranges from about 0.2 to about 0.6, y ranges from about 1.2 about 1.45, and z ranges from about 0.2 to about 0.35. In some embodiments, x ranges from out 0.2 to about 0.4, y ranges from about 1.3 to about 1.45, and z ranges from about 0.2 to out 0.35. In some embodiments, x is about 0.2, y is about 1.2, and z is about 0.35. In some lbodiments, x is about 0.3, y is about 1.45, and z is about 0.25. In some embodiments, x is out 0.4, y is about 1.35, and z is about 0.25. In some embodiments, x is about 0.4, y is about 1, and z is about 0.2. In some embodiments, x is about 0.6, y is about 1.2, and z is about 0.2.

066] In some embodiments, each R ¹ and R ² is independently C1-C30 alkoxyalkyl. In some lbodiments, each R ¹ and R ² is independently unsubstituted C1-C30 alkoxyalkyl.

In some embodiments, each R ¹ and R ² is 068] In some embodiments, one or two of R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are independently Ci- o alkoxy, and the rest of R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogen.

069] In some embodiments, each R ³ and R ⁶ is hydrogen, and each R ⁴ and R ⁵ is iependently C1-C30 alkoxy.

[)70] In some embodiments, two of R R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are and the res R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogen. some embodiments, each R ³ and R ⁶ is hydrogen, and each R ⁴ and R ⁵ is

072] In some embodiments, each R ⁹ and R ¹⁰ is hydrogen.

A .

073] In some embodiments, is of the formula

In some embodiments, In some lbodiments, each R and R is hydrogen, and each R and R is independently C1-C30 alkoxy

In some embodiments, is of the formula

076] In some embodiments, . In some ibodiments, each R ³ and R ⁶ is hydrogen, and each R ⁴ and R ⁵ is indepen C1-C30 alkoxy.

some embodiments, each R and R is hydrogen, and each R ⁴ and R ⁵ is

In some embodiments, is of the formula

me embodiments, R is hydrogen. In some embodiments, R is independently C1-C30 alkoxy.

some embodiments. R ³ is

In some embodiment In me embodiments, each R and

lbodiments, each R and R is y rogen or

In some embodiments, s o t e ormu a

some embodiments, two of R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are independently C1-C30 alkoxy, and tfr it of R ³ , R ⁴ , R ⁵ , R ⁶ , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷

d R ⁸ are independe R ⁸ are hydi

In some em bodiments, is of the formula

081] In some embodiments, provided is a method for synthesizing a black-to-transmissive ;ctrochromic polymer, comprising:

contacting Monomer 1, Monomer 2, Monomer 3 and Monomer 4 under polymerization conditions to form the black-to-transmissive electrochromic polymer,

wherein a ratio of Monomer 1 : Monomer 2: Monomer 3 : Monomer 4 is l :x:y' :z, x+y'+z is about 1, x ranges from about 0.2 to about 0.6, y' ranges from about 0.2 to about 0.45, and z ranges from about 0.2 to about 0.45; Monomer 1 is of the formula

Monomer 2 is of the formula

combination thereof, Monomer 3 is of the formula

and Monomer 4 is of the formula

wherein each of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ is independently hydrogen, optionally substituted C1-C30 alkyl, optionally substituted C2-C30 alkenyl, optionally substituted C2-C30 alkynyl, optionally substituted C2-C30 alkylcarbonyl, optionally substituted C1-C30 alkoxy, optionally substituted C3-C30 alkoxyalkyl, optionally substituted C2-C30 alkoxycarbonyl, optionally substituted C4-C30 alkoxycarbonylalky optionally substituted C1-C30 aminylcarbonyl, optionally substituted C4-C30 aminylalkyl, optionally substituted C1-C30 alkylaminyl, optionally substituted C1-C30 alkylsulfonyl, optionally substituted C3-C30 alkyl sulfonylalkyl, optionally substituted C ₆ -Ci8 aryl, optionally substituted C3-C15 cycloalkyl, optionally substituted C3-C30 cycloalkylaminyl, optionally substituted C5-C30 cycloalkylalkylaminyl, optionally substituted C5-C30 cycloalkylalkyl, optionally substituted C5-C30 cycloalkylalkyloxy, optionally substituted C1-C12 heterocyclyl, optionally substituted C1-C12

heterocyclyloxy, optionally substituted C3-C30 heterocyclylalkyloxy, optionally substituted C1-C30 heterocyclylalkyloxy, optionally substituted C1-C30

heterocyclylaminyl, optionally substituted C5-C30 heterocyclylalkylaminyl, optionall; substituted C2-C12 heterocyclylcarbonyl, optionally substituted C3-C30

heterocyclylalkyl, optionally substituted C1-C13 heteroaryl, or optionally substituted C3-C30 heteroarylalkyl.

082] In some embodiments, x ranges from about 0.2 to about 0.6, y' ranges from about 0.1 about 0.45, and z ranges from about 0.2 to about 0.35. In some embodiments, x ranges from out 0.2 to about 0.4, y' ranges from about 0.3 to about 0.45, and z ranges from about 0.2 to out 0.35. In some embodiments, x is about 0.2, y' is about 0.2, and z is about 0.35. In some lbodiments, x is about 0.3, y' is about 0.45, and z is about 0.25. In some embodiments, x is out 0.4, y' is about 0.35, and z is about 0.25. In some embodiments, x is about 0.4, y' is abou 1, and z is about 0.2. In some embodiments, x is about 0.6, y' is about 0.2, and z is about 0.2. In some embodiments, Monomer 1 is of the formula

In some embodiments, Monomer 2 is of the formula . In me embodiments, each R ³ and R ⁶ is hydrogen, and each R ⁴ and R ⁵ is independently C1-C30 coxy.

In some embodiments, Monomer 2 is

In some embodiments, Monomer 2 is of the formula In me embodiments, each R and R is hydrogen, and each R and R is indep

∞xy. In some embodiments, each R and R is hydrogen, and each R ⁴ and 087] In some embodiments, Monomer 2 is of the formula

. In some embodiments, ³ is hydrogen. In some

lbodiments, R ³ is independently C1-C30 alkoxy. In some

088] In some embodiments, Monomer 2 is of the formula

. In some embodiments, each R ³ and R ⁴ is independently drogen or C1-C30 alkoxy. In some embodiments, each R ³ and R ⁴ is independently hydrogen o

089] In some embodiments, Monomer 2 is of the formula

In some embodiments, two of R , R , R , R , R and R are iependently C1-C30 alkoxy, and the rest of R , R , R , R , R and R are hydrogen. In some

lbodiments, two of R ^: R ⁴ , R , R , R and R are and the rest of R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁸ are hydrogen. In some embodiments, Monomer 3 is of the formula

091] In some embodiments, Monomer 4 is of the formula

092] In some embodiments, the polymerization condition comprises K2CO3, PivOH, and (OAc) ₂ .

093] In some embodiments, the polymerization condition comprises about 2-3 equivalent K2CO3, about 0.1-0.5 equivalent of PivOH and about 0.01-0.05 equivalent of Pd(OAc)2 with jpect to 1 equivalent of Monomer 1.

094] In some embodiments, the polymerization condition comprises about 2.6 equivalent K2CO3, about 0.3 equivalent of PivOH and about 0.02 equivalent of Pd(OAc)2 with respect tc equivalent of Monomer 1.

095] In some embodiments, the polymerization condition further comprises an inert nosphere and a degassed solvent selected from N-methyl-2-pyrrolidone, N,N- riethylacetamide, and Ν,Ν-dimethylformamide, or a combination thereof.

096] In some embodiments, the polymerization condition further comprises a temperature about 100°C to about 200°C or about 140°C.

097] In some embodiments, the polymerization condition further comprises isolating the ick-to-transmissive electrochromic polymer.

098] In some embodiments, isolating the black-to-transmissive electrochromic polymer mprises

transferring the reaction mixture to a solvent of CH3OH; transferring the reaction mixture to an aqueous HC1 solution;

filtering the reaction mixture to obtain a solid material;

dissolving the solid material in chloroform and washing the solid material with an

aqueous HC1 solution;

concentrating and precipitating the solid material with CH3OH; and

obtaining the polymer by filtering and drying.

099] In some embodiments, provided is a black-to-transmissive electrochromic polymer nthesized by a method described herein.

100] In some embodiments, provided is a black-to-transmissive electrochromic polymer, lerein the polymer is synthesized by a method comprising

contacting Monomer 1, Monomer 2, Monomer 3 and Monomer 4 under a direct arylatior polymerization condition,

wherein a ratio of Monomer 1 : Monomer 2: Monomer 3 : Monomer 4 is l :x:y' :z, x+y'+z is about 1, x ranges from about 0.2 to about 0.6, y' ranges from about 0.2 to about 0.45, and z ranges from about 0.2 to about 0.45, and Monomer 1, Monomer 2, Monomer 3 and Monomer 4 are as described herein.

101] In some embodiments, the ratio of Monomer 1 : Monomer 2: Monomer 3 : Monomer < l :x:y' :z, x+y'+z is about 1, x ranges from about 0.2 to about 0.6, y' ranges from about 0.2 to out 0.45, and z ranges from about 0.2 to about 0.35.

102] In some embodiments, Monomer 1 is of the formula

103] In some embodiments, Monomer 2 is of the formula

In some embodiments, Monomer 3 is of the formula

In some embodiments, Monomer 4 is of the formula

106] In some embodiments, the polymer is a black-to-transmissive electrochromic njugated copolymer.

107] In some embodiments, the polymer has an average molecular weight of about 5.0-1O ⁾ a,

108] In some embodiments, the polymer has a polydispersity index of about 1.2-1.7.

109] In some embodiments, the polymer has a low band gap of about 1.61-1.65 eV.

110] In some embodiments, the black-to-transmissive electrochromic polymer has a rmalized absorbance from about 420 nm to about 680 nm of at least 0.7.

Ill] In some embodiments, the black-to-transmissive electrochromic polymer has a rmalized absorbance from about 420 nm to about 680 nm of at least 0.9. 112] In some embodiments, x is about 0.3-0.4. In some embodiments, y' is about 0.35- 15. In some embodiments, z is about 0.2-0.25.

113] In some embodiments, x is about 0.3, y' is about 0.45 and z is about 0.25.

114] In some embodiments, x is about 0.4, y' is about 0.35 and z is about 0.25.

115] In some embodiments, x is about 0.4, y' is about 0.4 and z is about 0.25.

116] In some embodiments, x is about 0.4, y' is about 0.4 and z is about 0.2.

117] In some embodiments, the polymer has an absorbance spectrum during 400-750 nm ated to a π- π* transition.

118] In some embodiments, provided is a black-to-transmissive electrochromic polymer n film, comprising an indium tin oxide (ITO) coated glass spin-coated with a black-to- nsmissive polymer described herein.

119] In some embodiments, the film changes color from black (L* is 0-60, a* is -10 to 5, d b* is -10 to 5) to transmissive (L* is 70 to 100, a* is -10 to 5, and b* is -10 to 5) with an plied voltage of 0-1.2 V, L* represents lightness, and a* and b* are hue and chroma values, jpectively.

120] In some embodiments, the film changes color from black (L* is 20-50, a* is -10 to 5, d b* is -10 to 5) to transmissive (L* is 80 to 90, a* is -10 to 5, and b* is -10 to 5) with an plied voltage of 0-1.2 V, L* represents lightness, and a* and b* are hue and chroma values, jpectively.

121] In some embodiments, the film changes color from black (L* is about 49.2, a* is -10 5, and b* is -10 to 5) to transmissive (L* is about 85, a* is -10 to 5, and b* is -10 to 5) with ai plied voltage of 0-1.2 V, L* represents lightness, and a* and b* are hue and chroma values, jpectively.

122] In some embodiments, the film changes color from black (L* is 20-50, a* is -5 to 0, d b* is -10 to 0) to transmissive (L* is 80 to 90, a* is -5 to 0, and b* is -5 to 0) with an appliec ltage of 0-1.2 V, L* represents lightness, and a* and b* are hue and chroma values, jpectively. 123] In some embodiments, the film changes color from black (L* is about 49.2, a* is -5 t and b* is -10 to 0) to transmissive (L* is about 85, a* is -5 to 0, and b* is -5 to 0) with an plied voltage of 0-1.2 V, L* represents lightness, and a* and b* are hue and chroma values, jpectively.

124] In some embodiments, the film changes color from black (L* is about 49.2, a* is out 3.6, b* is about -7.7) to transmissive (L* is about 85, a* is about -4.6, b* is about -5.8) th an applied voltage of about 0 to about 1.2 V, L* represents lightness, and a* and b* are hue d chroma values, respectively.

125] In some embodiments, the film changes color from black (L* = 49.2, a* = 3.6, b* = - 7) to transmissive (L* = 85, a* = -4.6, b* = -5.8) with an applied voltage of 0-1.2 V, L* presents lightness, and a* and b* are hue and chroma values, respectively.

126] In some embodiments, the film reaches an optical contrast of about 70% within 10 :onds on a small conductive substrate.

127] In some embodiments, the film has a coloration efficiency of at least 100 cm ² C ^"1 , at tst 125 cm ² C ^"1 , at least 150 cm ² C ^"1 , at least 175 cm ² C ^"1 , or at least 200 cm ² C ^"1 .

128] In some embodiments, the film has a coloration time of no more than 5 seconds and < caching time of no more than about 5 seconds.

129] In some embodiments, the film has a coloration time of about 3.73 seconds and a caching time of about 3.70 seconds on small conductive substrate, such as a conductive bstrate having an area of less than 1 square inch.

130] In some embodiments, the film has a coloration efficiency of at least 100 cm ² /C.

131] In some embodiments, the film has an optical loss of no more than 10% or no more in 5% after 1400 long-term oxidation-reduction switch cycles.

132] In some embodiments, provided is an electrochromic device, comprising:

an octadecyltrichlorosilane (OTS) modified indium tin oxide (ITO) electrode spin-coatec with a black-to-transmissive electrochromic polymer described herein as a working electrode; and

a colorless ITO as a counter electrode layer. 133] In some embodiments, the electrochromic device displays a contrast of about 40% or Dre.

134] In some embodiments, the electrochromic device switches color from black (a* is -5 0, b* is -10 to 0) when a potential of -IV is applied to transmissive (a* is -8 to 0, b* is -5 to 0 len a potential of 1.8 V is applied, and a* and b* are hue and chroma values, respectively, iring the transition of such color change, a*, b* consistently in a range of -13 to 0.

135] In some embodiments, the electrochromic device switches color from black (as scribed herein, e.g., L* = 37.8, a* = 2.5, b* = -6.4) when a potential of -1 V is applied to nsmissive (as described herein, e.g., L* = 72.6, a* = -8.0, b* = -6.5) when a potential of 1.8 V applied. Here, L* represents lightness (ranging from 0 to 100).

136] In some embodiments, the black polymer is a black-to-transmissive electrochromic njugated copolymer, which absorbs across the entire visible spectrum and realizes an obvious lor change from black (as described herein, e.g., L* = 49.2, a* = 3.6, b* = -7.7) to transmissiv i described herein, e.g., L* = 85, a* = -4.6, b* = -5.8) with an applied voltage of 0-1.2 V. An tical contrast as high as nearly 70 % can be reached within 10 seconds in electrochromic thin ms made of the black polymer, which is superior to reported black-to-transmissive

;ctrochromic materials. Moreover, long-term redox (oxidation-reduction) stability has been monstrated with an optical loss as low as 2.1 % after 1400 switching cycles. In addition, a ick-to-transmissive ECD based on the as-prepared electrochromic films can be designed usin^ ransparent indium tin oxide (ITO) as a counter electrode for charge storage. The ECD display ¾h contrasts for 43.6%, switching from a saturated black state (L* = 37.8, a* = 2.5, b* = -6.4) a transmissive state (L* = 72.6, a* = -8.0, b* = -6.5). These outstanding performances tentially make the black polymer a promising electrochromic material and can be incorporate< ;o privacy glass, smart windows and other related electrochromic devices.

137] The D-A approach, alternating electron-rich and electron-deficient moieties along a π- njugated backbone, has been proved especially valuable in the synthesis of dual-band and Dadly absorbing chromophores with useful photovoltaic and electrochromic properties. A romophore refers to an atom or group whose presence is responsible for the color of a mpound. An evolution of the two-band spectral absorption can be observed on varying relativ mpositions of electron-rich and electron-deficient substituents along the π-conjugated ckbone. In this regard, we have synthesized five black polymers P1-P5 in a direct arylation lymerization by varying feed ratios of electron-rich to electron-deficient species along the njugated backbone. For PI to P5, average molecular weights (Mn) and polydispersity index DI) are about 5.0 to 15.8 kDa and 1.2 to 1.7, respectively. Polydispersity index refers to either nlecular mass or degree of polymerization. Ratios of polymer components, electrochemical Dperties and GPC (Gel Permeation Chromatography) estimated molecular weights for PI to P: i listed in Table 1. Here, x, y', z are feed ratios of monomer 2, 3, and 4 with respect to Dnomer 1, and x+ y' + z = 1 with 1.0 equivalent of monomer 1. Examples of chemical rmulas of monomer 1, 2, 3 and 4 are presented in FIG. 1. Aonset stands for an onset of a lower- ergy optical transition; EHOMO is a HOMO (highest occupied molecular orbital) energy level o )lack polymer; ELUMO is a LUMO (lowest unoccupied molecular orbital) energy level of a ick polymer; E _ox is an onset oxidation potential of a black polymer; Eg is a band gap (Eg) of a ick polymer.

Table 1

138] In some embodiments, by changing feed ratios of monomer 1, 2, 3 and 4, five differer ick polymers (PI, P2, P3, P4 and P5) can be obtained with different polymer components and nlecular weights.

For PI concentration: Monomer 1 (250 mg, 0.57mmol), Monomer 2 (40 mg, O. l lmmol), onomer 3 (153 mg, 0.26mmol), and Monomer 4 (58 mg, 0.20mmol); obtained black polymer PI : mass = 0.26g, Mn = 15.8kDa, and PDI = 1.7. For P2 concentration: Monomer 1 (250 mg, 0.57mmol), Monomer 2 (60 mg, 0.17mmol), onomer 3 (153 mg, 0.26mmol), and Monomer 4 (42 mg, 0.14mmol); obtained black polymer P2: mass = 0.25g, Mn = 12.1kDa, and PDI = 1.5.

For P3 concentration: Monomer 1 (400 mg, 0.91mmol), Monomer 2 (128 mg, 0.36mmol), onomer 3 (190 mg, 0.32mmol), and Monomer 4 (67 mg, 0.23mmol); obtained black polymer P3 : mass = 0.36g, Mn = 5.5kDa, and PDI = 1.4.

For P4 concentration: Monomer 1 (400 mg, 0.91mmol), Monomer 2 (128 mg, 0.36mmol), onomer 3 (217 mg, 0.36mmol), and Monomer 4 (53 mg, 0.18mmol); obtained black polymer P4: mass = 0.28g, Mn = 6.4kDa, and PDI = 1.4.

For P5 concentration: Monomer 1 (300 mg, 0.68mmol), Monomer 2 (144 mg, 0.41mmol), onomer 3 (81.5 mg, 0.14mmol), and Monomer 4 (40 mg, 0.14mmol); obtained black polymer P5: mass = 0.25g, Mn = 5.0kDa, and PDI = 1.2.

139] FIG. 1 shows a reaction scheme for polymerizations of black polymers, in accordance exemplary embodiments of the present disclosure. All reagents can be obtained from Sigma drich or Acros and used without further purification unless otherwise noted. Ferrocene (Fc), d Octadecyltrichlorosilane (OTS) can be used without further purification and kept in a siccator. Propylene carbonate (PC, 99.5%) obtained from Sigma-Aldrich may be purified by a [vent purification system in vacuum. Tetrabutylammonium hexafluorophosphate (TBAPF6, > .0%)), platinum wire (99.0%) can be obtained from Sigma-Aldrich. ITO coated glass slides G-501N-CUV) can be obtained from Delta Technologies, Ltd., and sequentially cleaned with ionized water, ethanol and acetone.

140] As shown in FIG. 1, to synthesize the black polymers, 1 equivalent of Monomer 1 ma added to a reaction container, and followed by different ratios of Monomer 2, 3, 4 to obtain a lution. Next, K2CO3, PivOH and Pd(OAc) ₂ may also be added into the container to create a xture with the solution. Then O2 is removed from the container by, for example, purged with , and this process may be repeated for three times. A degassed solvent, such as N-methyl-2- rrolidone, Ν,Ν-dimethylacetamide, or Ν,Ν-dimethylformamide, can be added to the mixture i i container and the mixture may be heated, such as at a temperature of about 100°C to about 0°C or about 140°C for a period of time under nitrogen to create a reaction mixture comprisin i polymer. The hot reaction mixture may be first transferred to a solvent, such as CH3OH, and i transferred to an aqueous acid solution, such as 1M HC1. The reaction mixture can be tered to obtain a solid material which may be further dissolved in an organic solvent, such as loroform, and washed with an aqueous acid solution, such as 1M HC1 solution. The organic ase may be concentrated and precipitated with another solvent, such as CH3OH. The black lymer in a form of a black solid can be obtained by filtering and drying the organic phase.

141] In one example, at a first step, 1.0 equivalent of 3,4-propylenedioxythiophene (Prodot Dnomer 1 may be added to a Schlenk tube, and followed by different ratios of monomer 2, 3, 4 obtain a solution. Next, K2CO3 (e.g., 2.6 eq.), PivOH (e.g., 0.3 eq.) and Pd(OAc) ₂ (e.g., 0.02 .) may also be added into the tube to create a mixture with the solution. Then the tube may be pt under vacuum for about 5 min and purged with N ₂ , and this process may be repeated for ^' ee times. At a second step, degassed solvent N-methyl-2-pyrrolidone (NMP, and 1.0 g Dnomer 1 use 40 ml of solvent) can be added to the mixture in the tube and the tube may be ated in an oil bath at 140°C for 18 hour under nitrogen to create a reaction mixture. At a third :p, the hot reaction mixture may be first transferred to a solvent of CH3OH with a ratio of 1 : 1 d then transferred to 1M HC1 with stir. At a fourth step, the reaction mixture can be filtered to tain a solid material which may be further dissolved in chloroform and washed with 1M HC1 lution. At a fifth step, an organic phase may be concentrated and precipitate with CH3OH. At ; it step, the black polymer in a form of a black solid, can be obtained by filtering and drying thi ganic phase. PI to P5 were prepared accordingly.

142] In some embodiments, to fabricate ECDs with the obtained black polymers, firstly, nductive sides of cleaned ITO slides may be treated with a UV-ozone chamber for 20 mins to tain functionalized ITOs. Then the functionalized ITOs may be immersed into an OTS/hexan( lution (1 vol%) for 80 mins to form an OTS-modified ITO, and subsequently dried by nitrogei Dwing. Solutions of the black polymers in chloroform (60 mg/mL) then can be spin-coated 500 rpm) onto OTS-modified ITO electrodes to form thin electrochromic films. Thickness (~ 0 - 450 nm) of the spin-coated films can be controlled via adjusting a concentration of the ick polymer solution from 40-70 mg/mL.

143] To characterize the obtained black polymers and the ECDs, in some embodiments, ¾ d ¹³ C NMR (nuclear magnetic resonance) spectra may be recorded on a Brucker ARX 400 at 3 K with deuterized chlorofrom as solvent. Size exclusive chromatography (SEC) may be rformed in tetrahydrofuran under room temperature with calibration curve based on lystyrene standards. UV-vis-NIR spectra (ultraviolet-visible-Near-infrared spectra) may be jasured with an Agilent Technologies Cary 6000i UV-Vis-NIR or Agilent Cary 5000 UV-Vis- R spectrophotometer. All solution spectra may be collected in chloroform and thin film ectra from spin-coatinng samples on glass substrates.

144] In some embodiments, electrochemistry related studies of the polymer films may be rried out on BioLogic SP-150 in a traditional three-electrode system. A Pt wire may be used a ;ounter electrode, an Ag/AgCl reference electrode may be calibrated with Fc/Fc ⁺ (0.2 M of Fc ^' opylene carbonate (PC) in 0.2 M of TBAPF ₆ /PC), and the ITO-coated black polymer films ly be used as working electrodes. The Cyclic Voltammetry (CV) may be measured from 0 - IV at 40 mV/s scan rate in a 0.2 M TBAPFe /PC electrolyte solution. CV is a type of tentiodynamic electrochemical measurement, and is used to study the electrochemical Dperties of an analyte in solution. UV-vis spectra, Spectroelectrochemistry, Kinetic and Color jasurement may be recorded on an Agilent Cary 500 Scan UV-vis-NIR spectrophotometer, otographs of the polymer solutions and films may be illuminated with a D65 light source in ilding mode and recorded using a digital camera (Nikon D500) in a viewing booth (GTI aphic Technology, Inc.) All photographs are presented as received without further alteration.

145] FIG. 2A presents solution UV-visible absorption spectra of the black polymers from to P5 in chloroform in accordance to exemplary embodiments of the present disclosure. Inset FIG. 2A show colors of the black polymers in solution. As shown in FIG. 2A, the five spectra displayed broad "merging" band in the visible light region, which is different from typical D- polymer spectra with two single absorption bands. In some embodiments, with a low

Dportion of monomer 2, PI demonstrates a deficient absorption at a short- wavelength sorption of 458 nm and thus reveals a blue-green color. When the amount of monomer 2 ureases to 0.4 (i.e., P3), the absorbance area at low wavelength is rising and a difference in ;ensity between two peaks is diminishing. Hence, a further increase monomer 2 concentration ly realize a broader and completed absorption. As shown in FIG. 2A, with the increment of th ;io of the electron-rich moiety from P1-P4 (0.2-0.4), P4 demonstrates the most balanced and mogenous absorption spectrum, and almost covers the entire visible region, which is superior other reported black polymers. Further increasing the ratio of monomer 2 to 0.6, the curve of is uplifted around 420 nm, although it does not present entirely in the short- and long- tvelength transitions, and P5 in solution exhibits a dark blue color. Comparing the black lymers from P1-P5, bathochromic shift (except for P5) and hypsochromic shift is observed at ort- and long-wavelength transitions, respectively, which may be due to the increasing ratio oi ;ctron-rich moiety. This result may make the two transitions balance with each other and form 'merging" band. Bathochromic shift is a change of spectral band position in the absorption, ilectance, transmittance, or emission spectrum of a molecule to a longer wavelength (lower :quency). Hypsochromic shift is a change of spectral band position in the absorption, ilectance, transmittance, or emission spectrum of a molecule to a shorter wavelength (higher :quency).

146] In some embodiments, the polymer solutions (60 mg mL ^"1 ) may be spin-coated onto O slides, and the corresponding solid-state optical absorbance spectra are presented in FIG. 1. Insets in FIG. 2B show colors of the black polymers in solid states. All films demonstrated Dre black colors and bathochromic shifts relative to their solutions. This may be resulted from ¾her degree of order and a more planarity of the polymer chains in the solid state, which may id to a more black color.

147] In addition, the band gap (Eg) is an vital and indispensable factor for evaluating opto- ;ctronic properties, the values can be calculated by the onset of the lower-energy optical nsition (Aonset, Eg = 1240/ onset). Shown in FIG. 2B and Table 1, these five black polymers PI P5 have a low band gap from 1.61-1.65 eV.

148] FIG. 3 A shows measurement results of cyclic voltammograms of P4 in 0.2 M

JAPF6/PC at 40 mV/s; and FIG. 3B shows measurement results of spectroelectrochemistry of , in accordance to exemplary embodiments in the present disclosure. In some embodiments, ; film of P4 may be spin-coated onto ITO-coated glass from chloroform (60 mg mL ^"1 ). An ;ctrochemical oxidation of the film may be carried out in 0.2 M TBAPF ₆ /PC solution, with >/AgCl as a quasi-reference electrode (calibrated against Fc/Fc ⁺ ), and a platinum wire as the unter electrode. The applied potential may be increased from 0 to + 1.2 V vs. Ag/AgCl.

149] FIG. 3C shows data of lightness (L*) as a function of applied potential for spin-coated film, with J*, a*, and b* values listed. The insets in FIG. 3C are photographs of the films in lly neutral (left) and oxidized states (right), respectively. FIG. 3D shows data of square-wave tential-step chronoabsorptometry of P4 spin-coated on ITO (monitored at 500 nm, 0 to +1.2 \ . Ag/AgCl in 0.2 M TBAPFe/PC electrolyte solution) with a switching time for 100 s, 80 s, 60 40 s, 20 s, 10 s, 5 s, and 2 s.

150] In some embodiments, prior to other electrochemical and spectral investigation, a CV jasurement may be first conducted to probe and determine a redox potential range, which may cycled for several times at 40 mV/s to obtain some stable and reproducible curves. FIG. 3A zeals a 16th CV cycles of the P4 film, exhibiting a full and irreversible switch between 0-1.2 ^ th an onset oxidation potential (E _ox ) of 0.38 V versus an Ag/AgCl pseudoreference electrode, bsequently, the film may be neutralized at -0.2 V for 60 s at the same condition, and then anges of absorbance spectra from black to transmittance may be recorded under various plied voltages. FIG. 3B displays the spectroelectrochemical series spectra of P4 film. In some ibodiments, the film appears black in the neutral state, and shows a broad absorbance spectrur ring 400-750 nm related to the π- π* transition, while as the polymer film is doped, the broad ak in the visible region is depleted, and a polaronic and bipolaronic transition appear ccessively in the near-IR (800-1200 nm) and IR region (> 1200 nm). After the complete idation (-1.2 V), the absorption band arise beyond 1600 nm, meanwhile, a transmittance ange (ΔΤ = Tbieached - Tcoiored) may reach as high as nearly 70 % at 500 nm from the colored to i bleached state, which may allow highly transmissive films to the human eye.

151] In order to have an accurate assessment of the color characteristic changes during the ;ctrochemical switching, in some embodiments, colors can be measured quantitatively utilizin ; CIE 1976 L*a*b* color standards, where CIE 1976 is a color space adopted by the ternational Commission on Illumination (CIE) in 1976, L* represents lightness (ranging from 100), and a* and b* are hue and chroma values, respectively. More specifically, positive and gative a* values correspond to red and green hues, respectively, and positive and negative b* lues denote yellow and blue chromas. Colorimetrical measurements of the black polymer film ve been investigated, and P4 shows a relatively blacker color in comparison with others. The iults are listed in Table 2. Here, tc is a coloration time, tb is a bleaching time and CE is 1 oration efficiency.

Table 2

152] In some embodiments, colorimetrical measurements may also be performed via tying film thickness. For example, the absorption maximum for the three films of different ckness can be: Al = 0.43 a.u., A2 = 0.77 a.u., and A3 = 1.10 a.u. respectively, as shown in G. 3C. In a neutral state, the L* values of the films exhibit from 39.7 (A3 = 1.10 a.u.) to 67.4 1 = 0.43 a.u.). When the applied potential is added up to 0.4 V, the bleaching process may cur, which is consistent with the CV results. As the oxidation degree increases gradually, iible absorption regions are undergoing depletion, and polaronic and bipolaronic transitions iy progress with colors varying from colored to transmissive. In comparison, the film with the sorption maximum of 0.77 a.u. may obtain a maximum contrast for nearly 70 % from a deep ick color (L* = 49.2, a* = 3.6, b* = -7.7) to a highly transmissive near colorless state (L* = 85 = -4.6, b* = -5.8) upon doping.

153] Furthermore, coloration switching response and coloration efficiency may also be otal factors to assess electrochromic materials in practical applications of display and vices. In some embodiments, the film switching may be first examined using transmittance ange at a certain wavelength as a function of switch time by applying square-wave potential :ps for periods of 100, 80, 60, 40, 20, 10, 5, and 2 s. As shown in FIG. 3D, FIGs. 4A - D, and bles 2, the P4 film shows a largest transmittance change monitored, an excellent switching rformance as high as 69.7% at a longer switch time (100 s), also maintaining ΔΤ > 63.2 % at ' md above. However, the ΔΤ decreased to 46.0 % (a 23.72% loss) at a faster switching pulse oi i. Table 3 shows the ΔΤ of FIGs. 4A - D.

Table 3

154] In some embodiments, an interval time of 10 s (ΔΤιο = 68.4) may be chosen to estigate coloration rate and efficiency, as shown in FIGs. 5A - B. The measurements may be rformed by a combination of chronoamperometry and an in-situ UV-vis-NIR

ectrophotometer via alternating potentials from 0 to 1.2 V. Herein, a response time may be fined as the time required for a 90% change in the full transmittance at 500 nm. In some ibodiments, an as-prepared P4 film, the coloration time (tc) may be 3.73 s, and the bleaching e (tb) may be 3.7 s. The fast switching speed may be due to a good connection between an tive film (P4) and the OTS-functionalized ITO substrate.

155] A coloration efficiency (CE, η) is defined as the change in optical density (OD) per it of inserted charge (Q), which are measured in a simultaneous chronocoulometry and ronoabsorptometry experiment, with the percent transmittance during the switch monitored at i absorbance maxima. Chronocoulometry is used to study kinetics of chemical reactions, ifusion processes, and adsorption. In this technique, a potential step is applied to an electrode d the resulting cumulative charge vs. time is observed. This technique is very similar to ironoamperometry, except that the integrated charge is recorded in Chronocoulometry instead raw current. The coloration efficiency can be calculated via η = AOD/AQ. In some ibodiments, a CE value of 202.4 cm ² C ^"1 may be obtained for the P4 film (shown in Table 2 d FIG. 5B), which is superior and comparable to those of previously reported black polymer iterials.

156] In addition, stability is another crucial parameter in a practical utilization of

;ctrochromic materials. In some embodiments, the stability of repeated redox test may be rried out by repeating square-wave potential steps of 10 s (switching between 0 to 1.2 V vs. */AgCl) for 1400 cycles. As shown in FIG. 3D, the film demonstrated outstanding switching ibility with only a decrease of 2.1 % for transmittance changes.

157] In some embodiments, to verify utility of the black polymers, black-to-transmissive IDs may be assembled with P4 as a working electrode and a colorless ITO as a counter ;ctrode layer, respectively. Transmittance spectra of the ECDs in the neutral and bleaching tte may be measured across the entire visible region, and the detail changes may be shown in G. 6. Insets in FIG. 6 show photographs of a same device in reduction and oxidation states. In me embodiments, a potential of 1.8 V is applied to a device, and the device may become ghly transmissive (e.g., L* = 72.6, a* = -8, b* = -6.5). When the potential is decreased to -1.0 the device may recover to its black state (e.g., L* = 37.8, a* = 2.5, b* = -6.4) with a nsmittance contrast of about 43.6 % at 500 nm. Hence, polymer P4 can be validated to be an iective and valuable electrochromic material. Further efforts may be put into searching for a ;ll-matched courier electrode and constructing a high-performance ECD.

158] Based on measurement results, we find that through governing the variation of the urging band with various compositions, a black-to-transmissive electrochromic material with atively homogenous and broad absorption band can be synthesized. With 1 equivalent of onomer 1, the feed ratios of Monomers 2, 3 and 4 may range from 0.2 - 0.6, 0.2 - 0.45, 0.2 - 55, respectively. The synthesized black material can be realized a tunable color switching fron turated black to transmissive, which are superior to previous reported black-to-transmissive ;ctrochromic materials.

159] In this disclosure, a method for synthesizing black-to-transmissive electrochromic lymers is disclosed. Black polymers may be developed via controlling a monomer feed ratio i lirect arylation polymerization. Spectroelectrochemistry and colorimetry may exhibit a clear ick-to-transmissive upon electrochemical doping. An optimal electrochromic polymer monstrated high-performance in terms of most broad and uniform visible absorption, a high tical contrast, and long-term redox stability. Hence, this disclosure presents a strategy to sign and synthesis electrochromic materials. The high-performance resulting black-to- nsmissive polymers can be exploited in privacy glass, optical communication, data storage an me related electrochromic devices. 160] The disclosure described and claimed herein is not to be limited in scope by the ecific preferred embodiments disclosed herein, as these embodiments are intended as astrations of several aspects of the disclosure. Indeed, various modifications of the disclosure addition to those shown and described herein will become apparent to those skilled in the art )m the foregoing description. Such modifications are also intended to fall within the scope of i appended claims.