WO2018196792A1

WO2018196792A1 - Vertical benzodithiophene-based donor-acceptor polymers for electronic and photonic applications

Info

Publication number: WO2018196792A1
Application number: PCT/CN2018/084501
Authority: WO
Inventors: He Yan; Shangshang CHEN
Original assignee: The Hong Kong University Of Science And Technology
Priority date: 2017-04-25
Filing date: 2018-04-25
Publication date: 2018-11-01
Also published as: CN110536915B; CN110536915A

Abstract

Provided herein are donor-acceptor conjugated vertical benzodithiophene-based polymers, methods for their preparation and intermediates used therein, the use of formulations containing such polymers in the preparation of semiconductors in organic electronic devices, e.g., in organic photovoltaic and organic field-effect transistor devices, and to OE and OPV devices made from these formulations.

Description

VERTICAL BENZODITHIOPHENE-BASED DONOR-ACCEPTOR POLYMERS FOR ELECTRONIC AND PHOTONIC APPLICATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of United States provisional application 62/602,474, filed on 25 April 2017, the contents of it being hereby incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present disclosure relates to donor-acceptor conjugated polymers, methods for their preparation and intermediates used therein, the use of compositions containing such polymers in the preparation of semiconductors in organic electronic (OE) devices, e.g., in organic photovoltaic (OPV) and organic field-effect transistor (OFET) devices, and to OE and OPV devices made from these formulations.

BACKGROUND OF THE INVENTION

In recent years there has been growing interest in the use of organic semiconductors, including conjugated polymers, for various electronic applications.

One particular area of interest is the development of organic photovoltaics (OPV) . Organic semiconductors (OSCs) have found use in OPV as they allow devices to be manufactured by solution-processing techniques, such as spin casting and printing. Solution processing can be carried out more economically and on a larger scale as compared to evaporative techniques used to manufacture inorganic thin film devices.

The polymers commonly used in polymer solar cells typically consist of electron donating (donor or D) and electron accepting (acceptor or A) co-monomer units. It is convenient to use such a D-A alternating copolymer strategy to obtain polymers with low optical bandgaps as the highest occupied molecular orbital (HOMO) level of the polymer is generally located on the donor unit and the lowest unoccupied molecular orbital (LUMO) level generally on the acceptor unit. The commonly accepted model developed by Brabec, etc. indicates that carefully selected HOMO and LUMO energy levels are a basic requirement for high-performance polymer solar cells, because the open-circuit voltage (V _oc) of polymer solar cells is determined by the difference between the HOMO level of the polymer and the LUMO level of the acceptor. The HOMO/HOMO or LUMO/LUMO offsets between donor and acceptor should be small enough to minimize V _oc loss. By modifying the donor unit with electron-donating or withdrawing groups, the HOMO level of the D-A polymer can be effectively tuned, while the same can be done to tune the LUMO level by modifying the acceptor unit.

To achieve higher V _OC and reduce energy loss, it is important to explore new building blocks to construct novel conjugated polymers. In the design of donor polymers, the benzodithiophene (BDT) unit is a commonly used building block, and a series of BDT units have been developed by incorporating different substituents therein. Normally, the BDT unit is linked into the polymer backbone via the alpha positions of the thiophenes. It is also possible to connect the BDT unit into the polymer backbone via a vacant position on the phenyl group, e.g., a so called vertical BDT unit (vBDT) . However, such thiophene-vBDT-thiophene based donor polymers may exhibit poor performance. Thus, there exists a need to develop new vBDT containing donor polymers with improved properties.

SUMMARY OF THE INVENTION

Provided herein are donor-acceptor conjugated polymers with dramatically improved performance. The donor-acceptor conjugated polymers include repeating units comprising thiophene-vBDT-thiophenes exhibit strong temperature-dependent aggregation properties, relatively wide optical bandgap, and can achieve a favorable morphology with high charge mobilities in the formed OSCs.

In a first aspect, provided herein is a donor-acceptor conjugated polymer comprising one or more repeating units comprising a repeating unit of Formula 1:

wherein R ₁ is selected from the group consisting of H, F, Cl, Br, I, or CN, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by -O-, -S-, -C (O) -, -C (O) -O-, -O-C (O) -, -O-C (O) -O-, -CR ⁰=CR ⁰⁰-, or -C≡C-, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ₁ is aryl, heteroaryl, aryoxy, heteroaryloxy, arycarbonyl, heteroarycarbonyl, arycarbonyloxy, heteroarylcarbonyloxy, aryxycarbonyl, or heteroaryloxycarbonyl having 5 to 30 ring atoms; and

R ₂ is –CH ₂CH (R ₃) (R ₄) , wherein R ₃ and R ₄ are independently C ₁-C ₂₀ alkyl.

In a first embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the first aspect, wherein R ₂ is selected from:

In a second embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the first aspect, wherein R ₁ is H, F, Cl, Br, I, CN, C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, aryl, or heteroaryl.

In a third embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the first aspect, wherein R ₁ is H, aryl, or heteroaryl.

In a fourth embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the first aspect, wherein the repeating unit of Formula 1 is represented by a repeating unit of Formula 2:

wherein Ar is selected from the group consisting of:

wherein each R is independently selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by -O-, -S-, -C (O) -, -C (O) -O-, -O-C (O) -, -O-C (O) -O-, -CR ⁰=CR ⁰⁰-, or -C≡C-, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R is aryl, heteroaryl, aryoxy, heteroaryloxy, arycarbonyl, heteroarycarbonyl, arycarbonyloxy, heteroarylcarbonyloxy, aryxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms; and

R ₂ is selected from the group consisting of:

In a fifth embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the fourth embodiment of the first aspect, wherein R ₁ is H, aryl, or heteroaryl

In a sixth embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the fifth embodiment of the first aspect, wherein the average molecular weight of the conjugated donor-acceptor polymer is in a range from about 10,000 to about 100,000 kDa.

In a seventh embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the sixth embodiment of the first aspect wherein a solution of the donor-acceptor conjugated polymer exhibits a peak optical absorption spectrum in the film state that is red shifted by at least 80 nm as compared to the solution state.

In an eighth embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the sixth embodiment of the first aspect, further characterized in that the donor-acceptor conjugated polymer has an optical bandgap of 2.05 eV or lower.

In a ninth embodiment of the first aspect, provided herein is the donor-acceptor conjugated polymer of the fifth embodiment of the first aspect, wherein the donor-acceptor conjugated polymer is selected from a group consisting of:

wherein m is a whole number selected from 5 to 100.

In a second aspect provided herein is a composition comprising at least one of a fullerene acceptor and a non-fullerene acceptor; and the donor-acceptor conjugated polymer of the first aspect.

In a first embodiment of the second aspect, provided herein is the composition of the second aspect, wherein the fullerene acceptor is selected from the group consisting of:

Wherein each n is 1, 2, 4, 5, or 6;

each Ar is independently selected from the group consisting of monocyclic, bicyclic, polycyclic aryl, and monocyclic, bicyclic, and polycyclic heteroaryl, wherein each Ar may contain one to five of said aryl or heteroaryl each of which may be fused or linked;

each R ^x is independently selected from the group consisting of Ar, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O–) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ^x is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms;

each R ¹ is selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ¹ is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups, wherein the number of carbon that R ¹ contains is larger than 1, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group;

each Ar ¹ is independently selected from the group consisting of monocyclic, bicyclic and polycyclic heteroaryl groups, wherein each Ar ¹ may contain one to five of said heteroaryl groups each of which may be fused or linked;

each Ar ² is independently selected from aryl groups containing more than 6 atoms excluding H; and the fullerene ball represents a fullerene selected from the group consisting of C ₆₀, C ₇₀, and C ₈₄ fullerene.

In a second embodiment of the second aspect, provided herein is the composition of the second aspect, wherein the non-fullerene acceptor is selected from the group consisting of:

each R ₅ is independently selected from the group consisting of Ar, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cyclic alkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN, and wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group; or each R ₅ is independently aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms.

In a third embodiment of the second aspect, provided herein is the composition of the second aspect, wherein the composition has a power conversion efficiency of about 5.9 %to about 12%.

In a fourth embodiment of the second aspect, provided herein is the composition of the second aspect, wherein the non-fullerene acceptor is selected from the group consisting of:

wherein each R ₆ is (C ₁-C ₁₄) alkyl;

R ₇ is -CH ₂CH (R ₉) (R ₁₀) , wherein R ₉ and R ₁₀ are independently (C ₁-C ₂₀) alkyl; and R ₈ is (C ₁-C ₁₄) alkyl.

In a fifth embodiment of the second aspect, provided herein is the composition of the fourth embodiment of the second aspect, wherein R ₁ is H, F, Cl, Br, I, CN, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, (C ₃-C ₄₀) cycloalkyl, aryl, or heteroaryl.

In a sixth embodiment of the second aspect, provided herein is the composition of the second aspect, wherein the donor-acceptor conjugated polymer is selected from the group consisting of:

the non-fullerene acceptor is selected from the group consisting of:

wherein m is a whole number selected from 5 to 100.

In a third aspect provided herein is an organic electronic (OE) device comprising the composition of the second aspect.

In a first embodiment of the third aspect, provided herein is the OE device of the third aspect, characterized in that the OE device is an organic field effect transistor (OFET) device or an organic photovoltaic (OPV) device.

In a second embodiment of the third aspect, provided herein is the OE device of the first embodiment of the third aspect, wherein the OPV device has a power conversion efficiency of about 5.9 %to about 11.2%.

The present subject matter further relates to the use of a composition as described herein as a coating or printing ink, especially for the preparation of OE devices and rigid or flexible organic photovoltaic (OPV) cells and devices.

The present subject matter further relates to an OE device prepared from a composition as described herein. The OE devices contemplated in this regard include, without limitation, organic field effect transistors (OFET) , integrated circuits (IC) , thin film transistors (TFT) , radio frequency identification (RFID) tags, organic light emitting diodes (OLED) , organic light emitting transistors (OLET) , electroluminescent displays, organic photovoltaic (OPV) cells, organic solar cells (O-SC) , flexible OPVs and O-SCs, organic laser diodes (O-laser) , organic integrated circuits (O-IC) , lighting devices, sensor devices, electrode materials, photoconductors, photodetectors, electrophotographic recording devices, capacitors, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates, conducting patterns, photoconductors, electrophotographic devices, organic memory devices, biosensors and biochips.

The disclosed donor-acceptor conjugated polymers were found to show good processability and high solubility in organic solvents, and are thus especially suitable for large scale production using solution processing methods. At the same time, they show a low bandgap, high charge carrier mobility, high external quantum efficiency in BHJ solar cells, good morphology when combined with over a dozen fullerenes, and are promising materials for organic electronic OE devices, especially for OPV devices with high power conversion efficiency.

The compositions, methods and devices of the present disclosure provide surprising improvements in the efficiency of OE devices and the production thereof. Unexpectedly, the performance, lifetime, and the efficiency of OE devices prepared using the donor-acceptor conjugated polymers described herein can be dramatically improved. Furthermore, the composition described herein provides an astonishingly high level of film forming. Especially, the homogeneity and the quality of the films can be improved. In addition thereto, the present subject matter enables better solution printing of OE devices, especially OPV devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present disclosure will become apparent from the following description of the invention, when taken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts the UV-Vis absorption spectra of a PvBDTTAZ film and a PvBDTTAZ solution (0.04 mg mL ^-1 in chlorobenzene) at 20 ℃ and 100 ℃, and in thin film form.

FIG. 2 depicts the UV-Vis absorption spectra of the PvBDTTAZ-Th and PvBDTffBT-Th films.

FIG. 3 depict the cyclic voltammograms of FeCp ₂ ^0/+ and PvBDTTAZ.

FIG. 4 depicts the current-density-voltage curve of an exemplary PvBDTTAZ: O-IDTBR solar cell.

FIG. 5 depicts an external quantum efficiency (EQE) curve of an exemplary PvBDTTAZ: O-IDTBR solar cell.

It should be understood that the drawings described herein are for illustration purposes only. The drawings are not necessarily to scale, with emphasis generally being placed upon illustrating the principles of the present teachings. The drawings are not intended to limit the scope of the present teachings in any way.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Throughout the application, where compositions are described as having, including, or comprising specific components, or where processes are described as having, including, or comprising specific process steps, it is contemplated that compositions of the present teachings can also consist essentially of, or consist of, the recited components, and that the processes of the present teachings can also consist essentially of, or consist of, the recited process steps.

In the application, where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that the element or component can be any one of the recited elements or components, or the element or component can be selected from a group consisting of two or more of the recited elements or components. Further, it should be understood that elements and/or features of a composition, an apparatus, or a method described herein can be combined in a variety of ways without departing from the spirit and scope of the present teachings, whether explicit or implicit herein

The use of the terms "include, " "includes" , "including, " "have, " "has, " or "having" should be generally understood as open-ended and non-limiting unless specifically stated otherwise.

The use of the singular herein includes the plural (and vice versa) unless specifically stated otherwise. In addition, where the use of the term "about" is before a quantitative value, the present teachings also include the specific quantitative value itself, unless specifically stated otherwise. As used herein, the term "about" refers to a ±10%variation from the nominal value unless otherwise indicated or inferred.

It should be understood that the order of steps or order for performing certain actions is immaterial so long as the present teachings remain operable. Moreover, two or more steps or actions may be conducted simultaneously.

As used herein, a "p-type semiconductor material" or a "donor" material refers to a semiconductor material, for example, an organic semiconductor material, having holes as the majority current or charge carriers. In some embodiments, when a p-type semiconductor material is deposited on a substrate, it can provide a hole mobility in excess of about 10 ^-5 cm ²/Vs. In the case of field-effect devices, a p-type semiconductor also can exhibit a current on/off ratio of greater than about 10.

As used herein, an "n-type semiconductor material" or an "acceptor" material refers to a semiconductor material, for example, an organic semiconductor material, having electrons as the majority current or charge carriers. In some embodiments, when an n-type semiconductor material is deposited on a substrate, it can provide an electron mobility in excess of about 10 ^-5 cm ²/Vs. In the case of field-effect devices, an n-type semiconductor also can exhibit a current on/off ratio of greater than about 10.

As used herein, "mobility" refers to a measure of the velocity with which charge carriers, for example, holes (or units of positive charge) in the case of a p-type semiconductor material and electrons (or units of negative charge) in the case of an n-type semiconductor material, move through the material under the influence of an electric field. This parameter, which depends on the device architecture, can be measured using a field-effect device or space-charge limited current measurements.

As used herein, a compound can be considered "ambient stable" or "stable at ambient conditions" when a transistor incorporating the compound as its semiconducting material exhibits a carrier mobility that is maintained at about its initial measurement when the compound is exposed to ambient conditions, for example, air, ambient temperature, and humidity, over a period of time. For example, a compound can be described as ambient stable if a transistor incorporating the compound shows a carrier mobility that does not vary more than 20%or more than 10%from its initial value after exposure to ambient conditions, including, air, humidity and temperature, over a 3 day, 5 day, or 10 day period.

As used herein, fill factor (FF) is the ratio (given as a percentage) of the actual maximum obtainable power, (Pm or Vmp *Jmp) , to the theoretical (not actually obtainable) power, (Jsc *Voc) . Accordingly, FF can be determined using the equation:

FF = (Vmp *Jmp) / (Jsc *Voc)

where Jmp and Vmp represent the current density and voltage at the maximum power point (Pm) , respectively, this point being obtained by varying the resistance in the circuit until J *V is at its greatest value; and Jsc and Voc represent the short circuit current and the open circuit voltage, respectively. Fill factor is a key parameter in evaluating the performance of solar cells. Commercial solar cells typically have a fill factor of about 0.60%or greater.

As used herein, the open-circuit voltage (Voc) is the difference in the electrical potentials between the anode and the cathode of a device when there is no external load connected.

As used herein, the power conversion efficiency (PCE) of a solar cell is the percentage of power converted from absorbed light to electrical energy. The PCE of a solar cell can be calculated by dividing the maximum power point (Pm) by the input light irradiance (E, in W/m2) under standard test conditions (STC) and the surface area of the solar cell (Ac in m2) . STC typically refers to a temperature of 25℃ and an irradiance of 1000 W/m2 with an air mass 1.5 (AM 1.5) spectrum.

As used herein, a component (such as a thin film layer) can be considered "photoactive" if it contains one or more compounds that can absorb photons to produce excitons for the generation of a photocurrent.

As used herein, "solution-processable" refers to compounds (e.g., polymers) , materials, or compositions that can be used in various solution-phase processes including spin-coating, printing (e.g., inkjet printing, gravure printing, offset printing and the like) , spray coating, electrospray coating, drop casting, dip coating, blade coating, and the like.

As used herein, a "semicrystalline polymer" refers to a polymer that has an inherent tendency to crystallize at least partially either when cooled from a melted state or deposited from solution, when subjected to kinetically favorable conditions such as slow cooling, or low solvent evaporation rate and so forth. The crystallization or lack thereof can be readily identified by using several analytical methods, for example, differential scanning calorimetry (DSC) and/or X-ray diffraction (XRD) .

As used herein, "annealing" refers to a post-deposition heat treatment to the semicrystalline polymer film in ambient or under reduced/increased pressure for a time duration of more than 100 seconds, and "annealing temperature" refers to the maximum temperature that the polymer film is exposed to for at least 60 seconds during this process of annealing. Without wishing to be bound by any particular theory, it is believed that annealing can result in an increase of crystallinity in the polymer film, where possible, thereby increasing field effect mobility. The increase in crystallinity can be monitored by several methods, for example, by comparing the differential scanning calorimetry (DSC) or X-ray diffraction (XRD) measurements of the as-deposited and the annealed films.

As used herein, a "polymeric compound" (or "polymer" ) refers to a molecule including a plurality of one or more repeating units connected by covalent chemical bonds. A polymeric compound can be represented by General Formula I:

*- (- (Ma) _x- (Mb) _y-) _z*

General Formula I

wherein each Ma and Mb is a repeating unit or monomer. The polymeric compound can have only one type of repeating unit as well as two or more types of different repeating units. When a polymeric compound has only one type of repeating unit, it can be referred to as a homopolymer. When a polymeric compound has two or more types of different repeating units, the term "copolymer" or "copolymeric compound" can be used instead. For example, a copolymeric compound can include repeating units where Ma and Mb represent two different repeating units. Unless specified otherwise, the assembly of the repeating units in the copolymer can be head-to-tail, head-to-head, or tail-to-tail. In addition, unless specified otherwise, the copolymer can be a random copolymer, an alternating copolymer, or a block copolymer. For example, General Formula I can be used to represent a copolymer of Ma and Mb having x mole fraction of Ma and y mole fraction of Mb in the copolymer, where the manner in which co-monomers Ma and Mb is repeated can be alternating, random, region-random, region-regular, or in blocks, with up to z co-monomers present. In addition to its composition, a polymeric compound can be further characterized by its degree of polymerization (n) and molar mass (e.g., number average molecular weight (M) and/or weight average molecular weight (Mw) depending on the measuring technique (s) ) .

As used herein, "halo" or "halogen" refers to fluoro, chloro, bromo, and iodo.

As used herein, "alkyl" refers to a straight chain or branched saturated hydrocarbon group. Examples of alkyl groups include methyl (Me) , ethyl (Et) , propyl (e.g., n-propyl and isopropyl) , butyl (e.g., n-butyl, isobutyl, sec-butyl, tert-butyl) , pentyl groups (e.g., n-pentyl, isopentyl, neopentyl, tert-pentyl) , hexyl groups, and the like. In various embodiments, an alkyl group can have 1 to 40 carbon atoms (i.e., C ₁-C ₄₀ alkyl group) , for example, 1-30 carbon atoms (i.e., C ₁-C ₃₀ alkyl group) . In some embodiments, an alkyl group can have 1 to 6 carbon atoms, and can be referred to as a "lower alkyl group. " Examples of lower alkyl groups include methyl, ethyl, propyl (e.g., n-propyl and isopropyl) , and butyl groups (e.g., n-butyl, isobutyl, sec-butyl, tert-butyl) . In some embodiments, alkyl groups can be substituted as described herein. An alkyl group is generally not substituted with another alkyl group, an alkenyl group, or an alkynyl group.

As used herein, "alkenyl" refers to a straight chain or branched chain alkyl group having one or more carbon-carbon double bonds. Examples of alkenyl groups include ethenyl, propenyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl, hexadienyl groups, and the like. The one or more carbon-carbon double bonds can be internal (such as in 2-butene) or terminal (such as in 1-butene) . In various embodiments, an alkenyl group can have 2 to 40 carbon atoms (i.e., C ₂-C ₄₀ alkenyl group) , for example, 2 to 20 carbon atoms (i.e., C ₂-C ₂₀ alkenyl group) . In some embodiments, alkenyl groups can be substituted as described herein. An alkenyl group is generally not substituted with another alkenyl group, an alkyl group, or an alkynyl group.

As used herein, a "fused ring" or a "fused ring moiety" refers to a polycyclic ring system having at least two rings where at least one of the rings is aromatic and such aromatic ring (carbocyclic or heterocyclic) has a bond in common with at least one other ring that can be aromatic or non-aromatic, and carbocyclic or heterocyclic. These polycyclic ring systems can be highly p-conjugated and optionally substituted as described herein.

As used herein, "heteroatom" refers to an atom of any element other than carbon or hydrogen and includes, for example, nitrogen, oxygen, silicon, sulfur, phosphorus, and selenium.

As used herein, "aryl" refers to an aromatic monocyclic hydrocarbon ring system or a polycyclic ring system in which two or more aromatic hydrocarbon rings are fused (i.e., having a bond in common with) together or at least one aromatic monocyclic hydrocarbon ring is fused to one or more cycloalkyl and/or cycloheteroalkyl rings. An aryl group can have 6 to 24 carbon atoms in its ring system (e.g., C ₆-C ₂₄ aryl group) , which can include multiple fused rings. In some embodiments, a polycyclic aryl group can have 8 to 24 carbon atoms. Any suitable ring position of the aryl group can be covalently linked to the defined chemical structure. Examples of aryl groups having only aromatic carbocyclic ring (s) include phenyl, 1-naphthyl (bicyclic) , 2-naphthyl (bicyclic) , anthracenyl (tricyclic) , phenanthrenyl (tricyclic) , pentacenyl (pentacyclic) , and like groups. Examples of polycyclic ring systems in which at least one aromatic carbocyclic ring is fused to one or more cycloalkyl and/or cycloheteroalkyl rings include, among others, benzo derivatives of cyclopentane (i.e., an indanyl group, which is a 5, 6-bicyclic cycloalkyl/aromatic ring system) , cyclohexane (i.e., a tetrahydronaphthyl group, which is a 6, 6-bicyclic cycloalkyl/aromatic ring system) , imidazoline (i.e., a benzimidazolinyl group, which is a 5, 6-bicyclic cycloheteroalkyl/aromatic ring system) , and pyran (i.e., a chromenyl group, which is a 6, 6-bicyclic cycloheteroalkyl/aromatic ring system) . Other examples of aryl groups include benzodioxanyl, benzodioxolyl, chromanyl, indolinyl groups, and the like. In some embodiments, aryl groups can be substituted as described herein. In some embodiments, an aryl group can have one or more halogen substituents, and can be referred to as a "haloaryl" group. Perhaloaryl groups, i.e., aryl groups where all of the hydrogen atoms are replaced with halogen atoms (e.g., -C ₆F ₅) , are included within the definition of "haloaryl. " In certain embodiments, an aryl group is substituted with another aryl group and can be referred to as a biaryl group. Each of the aryl groups in the biaryl group can be substituted as disclosed herein.

As used herein, "heteroaryl" refers to an aromatic monocyclic ring system containing at least one ring heteroatom selected from oxygen (O) , nitrogen (N) , sulfur (S) , silicon (Si) , and selenium (Se) or a polycyclic ring system where at least one of the rings present in the ring system is aromatic and contains at least one ring heteroatom. Polycyclic heteroaryl groups include two or more heteroaryl rings fused together and monocyclic heteroaryl rings fused to one or more aromatic carbocyclic rings, non-aromatic carbocyclic rings, and/or non-aromatic cycloheteroalkyl rings. A heteroaryl group, as a whole, can have, for example, 5 to 22 ring atoms and contain 1 -5 ring heteroatoms (i.e., 5-20 membered heteroaryl group) . The heteroaryl group can be attached to the defined chemical structure at any heteroatom or carbon atom that results in a stable structure. Generally, heteroaryl rings do not contain O-O, S-S, or S-O bonds. However, one or more N or S atoms in a heteroaryl group can be oxidized (e.g., pyridine N-oxide, thiophene S-oxide, thiophene S, S-dioxide) . Examples of heteroaryl groups include, for example, the 5-or 6-membered monocyclic and 5-6 bicyclic ring systems shown below:

where T is O, S, NH, N-alkyl, N-aryl, N- (arylalkyl) (e.g., N-benzyl) , SiH ₂, SiH (alkyl) , Si (alkyl) ₂, SiH (arylalkyl) , Si (arylalkyl) ₂, or Si (alkyl) (arylalkyl) . Examples of such heteroaryl rings include pyrrolyl, furyl, thienyl, pyridyl, pyrim-idyl, pyridazinyl, pyrazinyl, triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl, thiazolyl, thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl, benzofuryl, ben-zothienyl, quinolyl, 2-methylquinolyl, isoquinolyl, quinox-alyl, quinazolyl, benzotriazolyl, benzimidazolyl, benzothia-zolyl, benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl, cinnolinyl, lH-indazolyl, 2H-indazolyl, indolizinyl, isobenzofuyl, naphthyridinyl, phthalazinyl, pte-ridinyl, purinyl, oxazolopyridinyl, thiazolopyridinyl, imida-zopyridinyl, furopyridinyl, thienopyridinyl, pyridopyrimidi-nyl, pyridopyrazinyl, pyridopyridazinyl, thienothiazolyl, thienoxazolyl, thienoimidazolyl groups, and the like. Further examples of heteroaryl groups include 4, 5, 6, 7-tetrahydroindolyl, tetrahydroquinolinyl, benzothienopyridinyl, benzofu-ropyridinyl groups, and the like. In some embodiments, heteroaryl groups can be substituted as described herein.

In certain embodiments, the donor-acceptor conjugated polymers described herein include a repeating unit (M1) of Formula 1:

wherein R ₁ is selected from the group consisting of H, F, Cl, Br, I, or CN, and (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by -O-, -S-, -C (O) -, -C (O) -O-, -O-C (O) -, -O-C (O) -O-, -CR ⁰=CR ⁰⁰-, or -C≡C-, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ₁ is aryl, heteroaryl, aryoxy, heteroaryloxy, arycarbonyl, heteroarycarbonyl, arycarbonyloxy, heteroarylcarbonyloxy, aryxycarbonyl, or heteroaryloxycarbonyl having 5 to 30 ring atoms; and

In certain embodiments, R ₁ is H, F, Cl, Br, I, CN, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aryoxy, heteroaryloxy, arycarbonyl, heteroarycarbonyl, arycarbonyloxy, heteroarylcarbonyloxy, aryxycarbonyl, heteroaryloxycarbonyl, ester, amide, acylamino, ether, thioether, amino, ketone, sulfone, sulfoxide, carbonate, or urea.

In certain embodiments, R ₁ is H, F, Cl, Br, I, CN, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, heterocycloalkyl, aryl, or heteroaryl wherein the aryl and heteroaryl are optionally substituted with halide, cyano, nitro, alkyl, cycloalkyl, amine, ether, thioether, ester, or amide.

In certain embodiments, R ₃ and R ₄ are independently (C ₂-C ₂₀) alkyl, (C ₂-C ₁₈) alkyl, (C ₂-C ₁₆) alkyl, (C ₂-C ₁) ₄ alkyl, (C ₃-C ₁₄) alkyl, (C ₄-C ₁₄) alkyl, (C ₅-C ₁₄) alkyl, (C ₆-C ₁₄) alkyl, (C ₈-C ₁₄) alkyl, (C ₈-C ₁₂) alkyl, (C ₈-C ₁₀) alkyl, (C ₁₀-C ₁₂) alkyl, (C ₂-C ₄) alkyl, (C ₂-C ₆) alkyl, (C ₄-C ₈) alkyl, or (C ₆-C ₈) alkyl.

In certain embodiments, R ₂ is selected from the group consisting of:

In certain embodiments, R ₁ is H, aryl, or heteroaryl, wherein the aryl and heteroaryl are optionally substituted with halide, cyano, nitro, alkyl, cycloalkyl, amine, ether, thioether, ester, or amide; and R ₃ and R ₄ are independently (C ₄-C ₁₄) alkyl.

The donor-acceptor conjugated polymers described herein can also include one or more repeating units other than M1. For example, the one or more repeating units (M2) can be selected from:

π-2 is an optionally substituted fused ring moiety;

Ar for each instance is independently an optionally substituted 5-or 6-membered aryl or heteroaryl group;

Z is a conjugated linear linker; and m, m'and m"independently are 0, 1, 2, 3, 4, 5 or 6.

In some embodiments, π-2 can be an optionally substituted polycyclic (C ₈-C ₂₂) aryl group or 8-22 membered heteroaryl group. For example, π-2 can have a planar and highly conjugated cyclic core which can be optionally substituted as disclosed herein. In various embodiments, π-2 can have a reduction potential (versus an SCE electrode and measured in, for instance, a THF solution) greater than (i.e., more positive than) about -3.0 V. In certain embodiments, π-2 can have a reduction potential greater than or equal to about -2.2 V. In particular embodiments, π-2 can have a reduction potential greater than or equal to about -1.2 V. Examples of suitable cyclic cores include naphthalene, anthracene, tetracene, pentacene, perylene, pyrene, coronene, fluorene, indacene, inde-nofluorene, and tetraphenylene, as well as their analogs in which one or more carbon atoms can be replaced with a heteroatom such as O, S, Si, Se, N, or P. In certain embodiments, π-2 can include at least one electron-withdrawing group.

In certain embodiments, π-2 can include two or more (e.g., 2-4) fused rings where each ring can be an optionally substituted five-, six-, or seven-membered ring. In some embodiments, π-2 can include a monocyclic ring (e.g., a 1, 3-dioxolane group or a derivative thereof including optional substituents and/or ring heteroatoms) covalently bonded to a second monocyclic ring or a polycyclic system via a spiro atom (e.g., a spiro carbon atom) .

In certain embodiments, π-2 can be selected from:

wherein p, p', s, s', v and v'are independently selected from C (R ₁) , N, and Si (R ₁) ;

each of q, q'and u are independently selected from C (O) , C=C (CN) ₂, -S-, -S (O) -, -S (O) ₂-, -O-, -Si (R ₁) (R ₂) -, -C (R ₁) (R ₂) -, -C (R ₁) (R ₂) -C (R ₁) (R ₂) -, and -CR ₁=CR ₂-;

each of R ₁ and R ₂, for each occurrence are independently be H, halogen, CN, (C ₁-C ₄₀) alkyl, (C ₁-C ₄₀) alkoxy, (C ₁-C ₄₀) alkylthio, (C ₁-C ₄₀) haloalkyl, (C ₆-C ₁₄) aryl, 5-14 membered heteroaryl, - (OCH ₂CH ₂) _tOR ^e, - (OCF ₂CF ₂) _tOR ^e, - (OCH ₂CF ₂) _tOR ^e, - (OCF ₂CH ₂) _tOR ^e, - (CH ₂CH ₂O) _tR ^e, - (CF ₂CF ₂O) _tR ^e, - (CH ₂CF ₂O) _tR ^e, or - (CF ₂CH ₂O) _tR ^e; wherein the C _6-14 aryl group and the 5-14 membered heteroaryl optionally substituted with 1-4 groups independently selected from halogen, CN, (C ₁-C ₄₀) alkyl groups, (C ₁-C ₄₀) alkoxy, (C ₁-C ₄₀) alkylthio, and (C ₁-C ₄₀) haloalkyl group; t is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; and R ^e is (C ₁-C ₂₀) alkyl or (C ₁-C ₄₀) haloalkyl; and b is 1, 2, 3 or 4.

In various embodiments, the linker Z can be a conjugated system by itself (e.g., including two or more double or triple bonds) or can form a conjugated system with its neighboring components. For example, in embodiments where Z is a linear linker, Z can be a divalent ethenyl group (i.e., having one double bond) , a divalent ethynyl group (i.e., having one tripe bond) , (C ₄-C ₄₀) alkenyl or alkynyl group that includes two or more conjugated double or triple bonds, or some other non-cyclic conjugated systems that can include heteroatoms such as Si, N, P, and the like. For example, Z can be selected from:

wherein R ₄ can be independently selected from H, a halogen, CN, a (C ₁-C ₂₀) alkyl, (C ₁-C ₂₀) alkoxy, and a (C ₁-C ₂₀) haloalkyl.

In certain embodiments, the repeating unit of Formula 1 is represented by a repeating unit of Formula 2:

wherein Ar is selected from the group consisting of:

wherein each R is independently selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by -O-, -S-, -C (O) -, -C (O) -O-, -O-C (O) -, -O-C (O) -O-, -CR ⁰=CR ⁰⁰-, or -C≡C-, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R is aryl, heteroaryl, aryoxy, heteroaryloxy, arycarbonyl, heteroarycarbonyl, arycarbonyloxy, heteroarylcarbonyloxy, aryxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms;

R ₁ is H, F, Cl, Br, I, CN, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, heterocycloalkyl, aryl, or heteroaryl, wherein the aryl and heteroaryl are optionally substituted with halide, cyano, nitro, alkyl, cycloalkyl, amine, ether, thioether, ester, or amide;

In certain embodiments, R is (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, (C ₃-C ₄₀) cycloalkyl, heterocycloalkyl, aryl, or heteroaryl. In certain embodiments, R is (C ₁-C ₁₀) straight chain alkyl, (C ₃-C ₁₀) branched chain alkyl, (C ₃-C ₁₀) cycloalkyl, heterocycloalkyl, aryl, or heteroaryl.

In certain embodiments, R ₃ and R ₄ are independently (C ₂-C ₂₀) alkyl, (C ₂-C ₁₈) alkyl, (C ₂-C ₁₆) alkyl, (C ₂-C ₁₄) alkyl, (C ₃-C ₁₄) alkyl, (C ₄-C ₁₄) alkyl, (C ₅-C ₁₄) alkyl, (C ₆-C ₁₄) alkyl, (C ₈-C ₁₄) alkyl, (C ₈-C ₁₂) alkyl, (C ₈-C ₁₀) alkyl, (C ₁₀-C ₁₂) alkyl, (C ₂-C ₄) alkyl, (C ₂-C ₆) alkyl, (C ₄-C ₈) alkyl, or (C ₆-C ₈) alkyl.

In certain embodiments, R ₂ is selected from the group consisting of:

In certain embodiments, R is (C ₁-C ₁₀) alkyl,

In certain embodiments, the donor-acceptor conjugated polymers comprise one or more repeating units of the following formula:

wherein n is a whole number selected from 5-200;

R is (C ₁-C ₁₀) alkyl;

R ₁ is H, Br, Cl, I, CN, alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, ether, amine, thioether, ester, amide, or acylamino; and

R ₂ is –CH ₂CH (R ₃) (R ₄) , wherein R ₃ and R ₄ are independently (C ₁-C ₂₀) alkyl.

In certain embodiments, R ₁ is H, aryl, or heteroaryl, wherein the aryl and thiophene are optionally substituted with halide, cyano, nitro, alkyl, cycloalkyl, amine, ether, thioether, ester, or amide; and R ₃ and R ₄ are independently (C ₄-C ₁₄) alkyl.

In certain embodiments, the donor-acceptor conjugated polymer is represented by the following formula:

wherein n is a whole number selected from 5-200;

X is S or N (C ₁-C ₁₀ alkyl) ;

R ₁ is H, Br, Cl, I, CN, alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, ether, amine, thioether, ester, amide, or acylamino;

In certain embodiments, R ₁ is H, aryl, or thiophene, wherein the aryl and thiophene are optionally substituted with halide, cyano, nitro, alkyl, cycloalkyl, amine, ether, thioether, ester, or amide.

In certain embodiments, R ₂ is selected from the group consisting of:

In certain embodiments, donor-acceptor conjugated polymers have an average molecular weight in the range of 10,000-1,000,000, 10,000-9000,000, 10,000-800,000, 10,000-700,000, 10,000-600,000, 10,000-500,000, 10,000-400,000, 10,000-300,000, 10,000-200,000, 10,000-150,000, 10,000-130,000, 10,000-120,000, 10,000-110,000, 20,000-110,000, 30,000-110,000, 40,000-110,000, 40,000-100,000, 40,000-90,000, 40,000-80,000, or 40,000-60,000 kDa. In other embodiments, donor-acceptor conjugated polymers have an average molecular weight in the range of 20,000-100,000, 10,000-100,000, 30,000-100,000, 30,000-90,000, 30,000-80,000, 30,000-70,000, 30,000-60,000, or 30,000-50,000 kDa. In other embodiments, donor-acceptor conjugated polymers have an average molecular weight in the range of 40,000 to 150,000 kDa.

The donor-acceptor conjugated polymers provided herein can exhibit temperature dependent aggregation properties. Temperature dependent aggregation of a the donor-acceptor conjugated polymers provided herein can be evaluated using any number of analytical methods known to those of skill in the art including, but not limited to, measuring light absorption of samples containing the donor material in a test solvent at various temperatures and measuring changes in absorption of samples containing the donor material in a test solvent at various temperatures.

As demonstrated in the examples below, solutions of the donor-acceptor conjugated polymers provided herein can exhibit significant bathochromic shifts in absorption when the temperature of the solution is varied and/or in comparison with the film state. For example, PvBDTTAZ in the film state exhibits a bathochromic red shift on the order of about 80 nm as compared with a dilute solution at 100 ℃.

In certain embodiments, the donor-acceptor conjugated polymers provided herein can exhibit a bathochromic shift in their absorption spectrum when measured in a solvent, such as chlorobenzene, 1, 2-dichlorobenzene, and combinations thereof, of more than about 40 nm, more than about 50 nm, more than about 60 nm, more than about 70 nm, more than about 80 nm, more than about 90 nm, more than about 100 nm, more than about 110 nm, more than about 120 nm, more than about 130 nm, more than about 140 nm, or more than about 150 nm. In other embodiments, the donor materials described herein can exhibit a bathochromic shift in their absorption spectrum when measured in dilute solution in a solvent, such as chlorobenzene, 1, 2-dichlorobenzene, and combinations thereof, of between about 40 nm to about 170 nm, about 40 nm to about 160 nm, about 40 nm to about 150 nm, about 40 nm to about 140 nm, about 40 nm to about 130 nm, about 40 nm to about 120 nm, about 40 nm to about 110 nm, about 40 nm to about 100 nm, about 40 nm to about 90 nm, about 40 nm to about 80 nm, about 40 nm to about 70 nm, or about 40 nm to about 60 nm.

In certain embodiments, provided herein is a composition comprising a donor-acceptor conjugated polymer described herein and a solvent (such as 1, 2-dichlorobenzene, 1, 3-dichlorobenzene, 1, 4-dichlorobenzene, 1, 2, 4-trichlorobenzene, toluene, o-xylene, m-xylene, p-xylene, chlorobenzene, 1, 2, 4-trimethylbenzene, 1, 2, 3-trimethylbenzene, 1, 3, 5-trimethylbenzene, chloroform and combinations thereof) , wherein the donor-acceptor conjugated polymers exhibits a peak optical absorption spectrum in the film state that is red shifted by about 20 nm to about 120 nm, about 20 nm to about 110 nm, about 20 nm to about 100 nm, about 20 nm to about 90 nm, about 20 nm to about 80 nm, about 30 nm to about 80 nm, or about 30 nm to about 60 nm, as compared with the donor-acceptor conjugated polymer in the solution state. In certain embodiments, the donor-acceptor conjugated polymer exhibits a peak optical absorption spectrum in the film state that is red shifted by at least about 20 nm, about 30 nm, about 40 nm, about 50 nm, about 60 nm, about 70 nm, about 70 nm, about 90 nm, about 100 nm, about 110 nm, or about 120 nm relative to the same donor-acceptor conjugated polymer in solution state.

Also provided herein is a composition comprising an acceptor (fullerene derivative or non-fullerene acceptors) and a donor-acceptor conjugated polymer as described herein.

In certain embodiments, the composition further comprises a solvent. The selection of the solvent can be determined based on the properties of the donor-acceptor conjugated polymer, acceptor, and solvent, such as solubility, stability, desired concentration of the donor-acceptor conjugated polymer, viscosity, and boiling point of the solvent. The selection of the appropriate solvent is well within the skill of a person of skill in the art. In certain embodiments, the solvent is at least one of 1, 2-dichlorobenzene, 1,3-dichlorobenzene, 1, 2, 4-trichlorobenzene, chlorobenzene, 1, 2, 4-trimethylbenzene, and chloroform.

In certain embodiments, the fullerene useful herein can be selected from the group consisting of:

wherein each n is 1, 2, 4, 5, or 6;

each Ar is independently selected from the group consisting of monocyclic, bicyclic, and polycyclic aryl, and monocyclic, bicyclic, and polycyclic heteroaryl, wherein each Ar may contain one to five of said aryl or heteroaryl each of which may be fused or linked;

each R ^x is independently selected from the group consisting of Ar, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O–) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ^x is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups;

each R ¹ is independently selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O–) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ¹ is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups, wherein the number of carbon that R ¹ contains is larger than 1;

each Ar ² is independently selected from aryl groups containing more than 6 atoms excluding H; and

wherein the fullerene ball represents a fullerene selected from the group consisting of C ₆₀, C ₇₀, C ₈₄, and other fullerenes.

In one embodiment, the fullerene is substituted by one or more functional groups selected from the group consisting of:

wherein n is 1, 2, 3, 4, 5, or 6;

each Ar is independently selected from the group consisting of monocyclic, bicyclic, polycyclic aryl, and monocyclic, bicyclic, and polycyclic heteroaryl, or may contain one to five such groups, either fused or linked;

each R ^x is independently selected from the group consisting of Ar, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ^x is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups;

each R ¹ is independently selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ¹ is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups, wherein the number of carbon that R ¹ contains is larger than 1;

each R is independently selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O–) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups;

In some embodiments, the formulation is further characterized in that the fullerene is selected from the group consisting of:

wherein n is 1, 2, 3, 4, 5, or 6;

each R is independently selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups.

wherein n is 1, 2, 3, 4, 5, or 6;

m is 1, 2, 4, 5, or 6;

q is 1, 2, 4, 5, or 6;

R ¹ and R ² are independently selected from the group consisting of (C ₁-C ₄) straight and branched chain alkyl groups; and

wherein the fullerene ball represents a fullerene from the group consisting of C ₆₀, C ₇₀, C ₈₄, and other fullerenes.

In certain embodiments, the non-fullerene acceptor is selected from the group consisting of:

wherein each R ₅ is independently selected from the group consisting of Ar, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ₅ is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups.

wherein R ₆ is (C ₁-C ₁₄) straight chain alkyl, (C ₃-C ₁₄) branched chain alkyl or (C ₃-C ₁₄) cycloalkyl;

R ₇ is –CH ₂CH (R ₉) (R ₁₀) , wherein R ₉ and R ₁₀ are independently C ₁-C ₂₀ alkyl; and

R ₈ is (C ₁-C ₁₄) straight chain alkyl, (C ₃-C ₁₄) branched chain alkyl or (C ₃-C ₁₄) cycloalkyl.

In certain embodiments, R ₆ is (C ₄-C ₁₀) straight chain alkyl, (C ₄-C ₁₀) branched chain alkyl or (C ₄-C ₁₀) cycloalkyl.

In certain embodiments, R ₆ is (C ₄-C ₁₀) straight chain alkyl, (C ₄-C ₁₀) branched chain alkyl or (C ₄-C ₁₀) cycloalkyl; and R ₈ is (C ₁-C ₆) straight chain alkyl, (C ₁-C ₆) branched chain alkyl or (C ₁-C ₆) cycloalkyl.

In certain embodiments, R ₉ and R ₁₀ are independently (C ₁-C ₆) alkyl.

In certain embodiments, R ₉ and R ₁₀ are independently (C ₁-C ₆) alkyl; and R ₈ is (C ₁-C ₆) straight chain alkyl, (C ₁-C ₆) branched chain alkyl or (C ₁-C ₆) cycloalkyl.

In an exemplary embodiment, an organic electronic (OE) device comprises a coating or printing ink containing the formulation. Another exemplary embodiment is further characterized in that the OE device is an organic field effect transistor (OFET) device. Another exemplary embodiment is further characterized in that the OE device is an organic photovoltaic (OPV) device.

Formulations of the present teachings can exhibit semiconductor behavior such as optimized light absorption/charge separation in a photovoltaic device; charge transport/recombination/light emission in a light-emitting device; and/or high carrier mobility and/or good current modulation characteristics in a field-effect device. In addition, the present formulations can possess certain processing advantages such as solution-processability and/or good stability (e.g., air stability) in ambient conditions. The formulations of the present teachings can be used to prepare either p-type (donor or hole-transporting) , n-type (acceptor or electron-transporting) , or ambipolar semiconductor materials, which in turn can be used to fabricate various organic or hybrid optoelectronic articles, structures and devices, including organic photovoltaic devices and organic light-emitting transistors.

EXAMPLES

Example 1 -Synthesis of PvBDTTAZ

Step 1:

4, 8-bis (4- (2-decyltetradecyl) thiophen-2-yl) benzo [1, 2-b: 4, 5-b'] dithiophene (S1) .

To a solution of 3- (2-decyltetradecyl) thiophene (4.2 g, 10 mmol) in THF (40 mL) was added butyllithium solution (5 mL, 2.0 M in hexane) dropwise at 0 ℃. The solution was then allowed to stir at 0 ℃ for 1 h before benzo [1, 2-b: 4, 5-b'] dithiophene-4, 8-dione (550 mg, 2.5 mmol) was added in one portion. The resulting yellow solution was allowed to stir at 50 ℃ for 2 h before SnCl ₂ 2H ₂O (11 g, 50 mmol) in 10 %HCl solution (40 mL) was added and the solution was allowed to stir for additional 2 h. Hexane was added to the mixture and was followed by washing with water for three times and dried over sodium sulphate. The resulting yellow oil was purified by flash chromatography to get pure product as yellowish oil (1.8 g, 70 %) .

¹H NMR: (400 MHz, CDCl ₃) 7.65 (d, J = 5.6 Hz, 2H) , 7.45 (s, 2H) , 7.29 (d, J = 1.2 Hz, 2H) , 7.08 (d, J = 0.8 Hz, 2H) , 2.66 (d, J = 6.8 Hz, 4H) , 1.80 –1.69 (br, 2H) , 1.48 –1.21 (m, 80H) , 0.88 (t, J = 6.8 Hz, 12H) .

¹³C NMR: (100 MHz, CDCl ₃) δ 142.50, 139.31, 139.27, 136.73, 130.18, 127.76, 124.36, 123.52, 122.09, 39.31, 35.24, 33.72, 32.14, 30.29, 29.93, 29.86, 29.59, 26.97, 22.91, 14.34.

Step 2:

4, 8-bis (5-bromo-4- (2-decyltetradecyl) thiophen-2-yl) benzo [1, 2-b: 4, 5-b'] dithiophene (S2)

To a solution of S1 (1g, 0.93 mmol) was added NBS (375.9 mg, 2.1 mmol) in one portion at 0 ℃ and the reaction was allowed to stir overnight. After the reaction finished, the solvent was removed on a rotary evaporator. Then, the residue was purified by flash chromatography over silica gel eluting with hexane to get pure product was yellowish oil (960 mg, 87%) .

¹H NMR: (400 MHz, CDCl ₃) 7.60 (d, J = 6.0 Hz, 2H) , 7.47 (d, J = 5.6 Hz, 2H) , 7.14 (s, 2H) , 2.61 (d, J = 7.2 Hz, 4H) , 1.80 –1.69 (br, 2H) , 1.48 –1.21 (m, 80H) , 0.89 (t, J = 6.4 Hz, 12H) .

¹³C NMR: (100 MHz, CDCl ₃) δ 141.94, 139.31, 138.98, 136.72, 129.99, 128.20, 123.68, 123.20, 110.85, 38.81, 34.55, 33.77, 32.14, 30.27, 29.92, 29.90, 29.88, 28.58, 26.87, 22.91, 14.33.

Step 3:

5, 6-difluoro-2-propyl-4, 7-bis (5- (trimethylstannyl) thiophen-2-yl) -2H-benzo [d] [1, 2, 3] triaz ole (TAZ) .

To a solution of 5, 6-difluoro-2-propyl-4, 7-di (thiophen-2-yl) -2H-benzo [d] [1, 2, 3] triazole (1.0248 g, 2.84 mmol) in tetrahydrofuran (120 mL) , lithium diisopropylamide (3.4 mL, 2.0 M in THF, 6.8 mmol) was added dropwise under N ₂. After ther reaction mixture was stirred for 2 h at -78 ℃, trimethyltin chloride (7.7 mL, 1.0 M in hexane, 7.7 mmol) was added dropwise. The reaction mixture was stirred for 12 h at room temperature. Then, aqueous potassium fluoride was added and the mixture was extracted with diethyl ether for three time. The combined organic phase was washed with water followed by brine. Then the solution was dried over Na ₂SO ₄ and concentrated under reduced pressure. The crude product was recrystallized from chloroform/isopropyl alcohol to get the product as yellow green needle (535 mg, 27 %) .

¹H NMR: (400 MHz, CDCl ₃) 8.38 (t, J = 3.2 Hz, 2H) , 7.32 (m, 2H) , 4.77 (t, J = 6.8 Hz, 2H) , 2.22 (m, 2H) , 1.05 (t, J = 7.2 Hz, 3H) , 0.44 (s, 18H) .

¹³C NMR: (100 MHz, CDCl ₃) δ 141.50, 137.92, 135.56, 131.03, 58.66, 23.68, 11.40.

¹⁹F NMR: (376.5 MHz, CDCl ₃) δ -134.27.

Step 4:

The polymer can be synthesized by either microwave reaction or conventional reaction. To a mixture of monomer S2 (60.6 mg, 0.051 mmol) , 5,6-difluoro-2-propyl-4, 7-bis (5- (trimethylstannyl) thiophen-2-yl) -2H-benzo [d] [1, 2, 3] triaz ole (TAZ monomer) , Pd ₂ (dba) ₃ (0.5 mg, 0.00055 mmol) and P (o-tol) ₃ (1 mg, 0.0033 mmol) were added 300 μL chlorobenzene in a glove box protected with N ₂. The reaction mixture was then sealed and heated at 140 ℃ for 2 hours assisted with microwave, or 140 ℃ for 2 days under conventional heating. The mixture was cooled to r. t. and 10 mL toluene was added before precipitated with methanol. The solid was collected by filtration, and loaded into an extraction thimble and washed with hexane then dichloromethane. The polymer was finally collected from chloroform. The chloroform solution was then concentrated by evaporation, precipitated into methanol. The solid was collected by filtration and dried in vacuo to get the polymer as orange red solid (65 mg, 92 %) .

Example 2 –Synthesis of PvBDTTAZ-Th

( (2, 6-bis (5-methylthiophen-2-yl) benzo [1, 2-b: 4, 5-b'] dithiophene-4, 8-diyl) bis (3- (2-decyltetradecyl) thiophene-5, 2-diyl) ) bis (trimethylsilane) (S5)

A mixture of S4 (860 mg, 0.647 mmol) , tributyl (5-methylthiophen-2-yl) stannane (600.9 mg, 1.55 mmol) , Pd ₂ (dba) ₃ (11 mg, 0.02 mmol) and P (o-tol) ₃ (24 mg, 0.08 mmol) in 10 mL THF was refluxed overnight under N2. The reaction mixture was then cooled to r. t. and the solvent was evaporated. The residue was purified by flash column chromatography (eluent: n-hexane) to get the product as yellow liquid (573.8 mg, 65%) .

4, 8-bis (5-bromo-4- (2-decyltetradecyl) thiophen-2-yl) -2, 6-bis (5-methylthiophen -2-yl) benzo [1, 2-b: 4, 5-b'] dithiophene (S6)

N-Bromosuccinimide (263.5 mg, 1.48 mmol) was added to a mixture of S5 (1.01 g, 0.74 mmol) and silica gel (20 mg) in 20 mL chloroform at 0 ℃. The reaction mixture was warmed to r. t. and stirred overnight. After washed with water, the organic phase was dried with Na ₂SO ₄ and the solvent was evaporated. The residue was purified with flash column chromatography (eluent: n-hexane) to get the product as yellow solid (0.917 g, 90 %) .

The PvBDTTAZ-Th polymer can be synthesized by either microwave reaction or conventional reaction. To a mixture of monomer S6 (47.9 mg, 0.035 mmol) , S3 (23.9 mg, 0.035 mmol) , Pd ₂ (dba) ₃ (1.1 mg, 0.002 mmol) and P (o-tol) ₃ (2.4 mg, 0.008 mmol) was added 0.4 mL of chlorobenzene in a glove box protected with N ₂. The reaction mixture was then sealed and heated at 140 ℃ for 2 days (or at 140 ℃ for 2 hours for microwave reaction) . The mixture was cooled to r. t. and 10 mL toluene was added before precipitated with methanol. The solid was collected by filtration, and loaded into an extraction thimble and washed successively with CH ₂Cl ₂ and CHCl ₃. The polymer was finally collected from CHCl ₃. The CHCl ₃ solution was then concentrated by evaporation, precipitated into methanol. The solid was collected by filtration and dried in vacuo to get the polymer as dark red solid.

Example 3 –the Synthesis of PvBDTffBT

The PvBDTffBT-Th polymer can be synthesized by either microwave reaction or conventional reaction. To a mixture of monomer S6 (19.7 mg, 0.014 mmol) , S7 (9.5 mg, 0.014 mmol) , Pd ₂ (dba) ₃ (1.1 mg, 0.002 mmol) and P (o-tol) ₃ (2.4 mg, 0.008 mmol) was added 0.2mL of chlorobenzene in a glove box protected with N2. The reaction mixture was then sealed and heated at 140 ℃ for 2 days (or at 140 ℃ for 2 hours for microwave reaction) . The mixture was cooled to r. t. and 10 mL toluene was added before precipitated with methanol. The solid was collected by filtration, and loaded into an extraction thimble and washed successively with CH ₂Cl ₂, CHCl ₃ and toluene. The polymer was finally collected from toluene. The toluene solution was then concentrated by evaporation, precipitated into methanol. The solid was collected by filtration and dried in vacuo to get the polymer as red solid.

Example 4 –the Synthesis of PvBDTTAZ-B

The PvBDTTAZ-B polymer can be synthesized by either microwave reaction or conventional reaction. To a mixture of monomer S8 (23.5 mg, 0.018 mmol) , S3 (12.1 mg, 0.018 mmol) , Pd ₂ (dba) ₃ (1.1 mg, 0.002 mmol) and P (o-tol) ₃ (2.4 mg, 0.008 mmol) was added 0.2 mL of chlorobenzene in a glove box protected with N2. The reaction mixture was then sealed and heated at 140 ℃ for 2 days (or at 140 ℃ for 2 hours for microwave reaction) . The mixture was cooled to r. t. and 10 mL toluene was added before precipitated with methanol. The solid was collected by filtration, and loaded into an extraction thimble and washed successively with CH ₂Cl ₂ and CHCl ₃. The polymer was finally collected from CHCl ₃. The CHCl ₃ solution was then concentrated by evaporation, precipitated into methanol. The solid was collected by filtration and dried in vacuo to get the polymer as red solid.

Example 5 -Characterization of Polymers

Example 5a: Optical properties

Film UV-Vis absorption spectra of polymers from Example 2, 3, and 4 were acquired on a Perkin Elmer Lambda 20 UV/VIS Spectrophotometer. All film samples were spin-cast on glass/ITO/ZnO substrates. Solution UV-Vis absorption spectra at elevated temperatures were collected on a Perkin Elmer Lambda 950 UV/VIS/NIR Spectrophotometer. The temperature of the cuvette was controlled with a Perkin Elmer PTP 6+6 Peltier System, which is supplied by a Perkin Elmer PCB 1500 Water Peltier System. Before each measurement, the system was held for at least 10 min at the target temperature to reach thermal equilibrium. A cuvette with a stopper (Sigma Z600628) was used to avoid volatilization during the measurement. The onset of the absorption is used to estimate the polymer bandgap. The optical absorption spectrum of PvBDTTAZ is shown in FIG. 1, and the optical bandgap of PvBDTTAZ is calculated to be 2.05 eV estimated from the absorption onset. Similarly, the absorption spectra of PvBDTTAZ-Th and PvBDTffBT-Th are presented in in FIG. 2, and their optical bandgap are determined to be 1.90 and 1.65 eV, respectively.

Example 5b: Electronic properties

Cyclic voltammetry was carried out on a CHI760E electrochemical workstation with three electrodes configuration, using Ag/AgCl as the reference electrode, a Pt plate as the counter electrode, and a glassy carbon as the working electrode. Polymers were drop-cast onto the electrode from DCB solutions to form thin films. 0.1 mol L ^-1 tetrabutylammonium hexafluorophosphate in anhydrous acetonitrile was used as the supporting electrolyte. Potentials were referenced to the ferrocenium/ferrocene couple by using ferrocene as external standards in acetonitrile solutions. The scan rate is 0.05 V s ^-1. The Cyclic voltammograms of FeCp ₂ ^0/+ and PvBDTTAZ is shown in FIG. 2. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital energy levels (LUMO) of PvBDTTAZ are measured to be -5.47 and -3.42 eV, respectively.

Example 6 -Device Fabrication and Characterization

Pre-patterned ITO-coated glass with a sheet resistance of ～15 Ω per square was used as the substrate. It was cleaned by sequential ultra-sonication in soap deionized water, deionized water, acetone and isopropanol for 30 min at each step. The washed substrates were further treated with a UV-O ₃ cleaner (Novascan, PSD Series digital UV ozone system) for 30 min. A topcoat layer of ZnO (The diethylzinc solution 15 wt %in toluene, diluted with tetrahydrofuran) was spin-coated onto the ITO substrate at a spinning rate of 5000 rpm for 30 s and then baked in air at 150 ℃ for 20 min. Active layer solutions (polymer: acceptor weight ratio 1: 1.5) were prepared in 1, 2, 4-trimethylbenzene. The polymer concentration is 12 mg/mL. To completely dissolve the polymer, the active layer solution was stirred on a hot plate at 100 ℃ for at least 1 h. Before spin coating, both the polymer solution was cooled down to room temperature. Active layers were spin coated from the warm polymer solution onto the preheated substrate in a N ₂ glovebox at ～700 -1200 rpm. The blend films were annealed at 80 ℃ for 5 min before being transferred to the vacuum chamber of a thermal evaporator inside the same glovebox. At a vacuum level of 1 × 10 ^-4 Pa, a thin layer (7 nm) of V ₂O ₅ or MoO ₃ was deposited as the anode interlayer, followed by deposition of 100 nm of Al as the top electrode. All cells were encapsulated using epoxy inside the glovebox. Device J–V characteristics was measured under air mass 1.5 global (100 mW cm ^-2) using a Newport Class 1A solar simulator (94021A, a Xenon lamp with an AM1.5G filter) . A standard crystalline Si solar cell with a KG5 filter was purchased from PV Measurements and calibrated by Newport Corporation. The light intensity was calibrated using the standard Si diode to bring spectral mismatch to unity. J–V characteristics were recorded using a Keithley 2400 source meter unit. Typical cells have devices area of ～5.9 mm ², which is defined by a metal mask with an aperture aligned with the device area. EQEs were characterized using an Enlitech QE-SEQE system equipped with a standard Si diode. Monochromatic light was generated from a Newport 300 W lamp source. The V _oc, J _sc, FF and PCE of OPV devices in the present teaching are summarized in the following table. The J-V and EQE curves of PvBDTTAZ: O-IDTBR based devices are shown in FIG. 3 and FIG. 4, respectively.

Table 1. Solar cell performance of PvBDTTAZ with different acceptors. The averages were calculated from at least 15 devices.

Table 2. Solar cell performance of O-IDTBR with different vBDT-based donor polymers.

Claims

A donor-acceptor conjugated polymer comprising one or more repeating units comprising a repeating unit of Formula 1:

wherein R ₁ is selected from the group consisting of H, F, Cl, Br, I, or CN, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by -O-, -S-, -C (O) -, -C (O) -O-, -O-C (O) -, -O-C (O) -O-, -CR ⁰=CR ⁰⁰-, or -C≡C-, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ₁ is aryl, heteroaryl, aryoxy, heteroaryloxy, arycarbonyl, heteroarycarbonyl, arycarbonyloxy, heteroarylcarbonyloxy, aryxycarbonyl, or heteroaryloxycarbonyl having 5 to 30 ring atoms; and

R ₂ is –CH ₂CH (R ₃) (R ₄) , wherein R ₃ and R ₄ are independently C ₁-C ₂₀ alkyl.
The donor-acceptor conjugated polymer of claim 1, wherein R ₂ is selected from:
The donor-acceptor conjugated polymer of claim 1, wherein R ₁ is H, F, Cl, Br, I, CN, C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, aryl, or heteroaryl.
The donor-acceptor conjugated polymer of claim 1, wherein R ₁ is H, aryl, or heteroaryl.
The donor-acceptor conjugated polymer of claim 1, wherein the repeating unit of Formula 1 is represented by a repeating unit of Formula 2:

wherein Ar is selected from the group consisting of:

wherein each R is independently selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by -O-, -S-, -C (O) -, -C (O) -O-, -O-C (O) -, -O-C (O) -O-, -CR ⁰=CR ⁰⁰-, or -C≡C-, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R is aryl, heteroaryl, aryoxy, heteroaryloxy, arycarbonyl, heteroarycarbonyl, arycarbonyloxy, heteroarylcarbonyloxy, aryxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms; and

R ₂ is selected from the group consisting of:
The donor-acceptor conjugated polymer of claim 5, wherein R ₁ is H, aryl, or heteroaryl.
The donor-acceptor conjugated polymer of claim 6, wherein the average molecular weight of the conjugated donor-acceptor polymer is in a range from about 10,000 to about 100,000 kDa.
The donor-acceptor conjugated polymer of claim 7, wherein a solution of the donor-acceptor conjugated polymer exhibits a peak optical absorption spectrum in the film state that is red shifted by at least 80 nm as compared to the solution state.
The donor-acceptor conjugated polymer of claim 7, further characterized in that the donor-acceptor conjugated polymer has an optical bandgap of 2.05 eV or lower.
The donor-acceptor conjugated polymer of claim 6, wherein the donor-acceptor conjugated polymer is selected from a group consisting of:

wherein m is a whole number selected from 5 to 100.
A composition comprising at least one of a fullerene acceptor and a non-fullerene acceptor; and the donor-acceptor conjugated polymer of claim 1.
The composition of claim 11, wherein the fullerene acceptor is selected from the group consisting of:

wherein

each n is 1, 2, 4, 5, or 6;

each Ar is independently selected from the group consisting of monocyclic, bicyclic, polycyclic aryl, and monocyclic, bicyclic, and polycyclic heteroaryl, wherein each Ar may contain one to five of said aryl or heteroaryl each of which may be fused or linked; each R ^x is independently selected from the group consisting of Ar, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O–) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ^x is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms;

each R ¹ is selected from the group consisting of (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cycloalkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O) –O–, –O–C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, and wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN; or R ¹ is aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms unsubstituted or substituted by one or more non-aromatic groups, wherein the number of carbon that R ¹ contains is larger than 1, wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group;

each Ar ¹ is independently selected from the group consisting of monocyclic, bicyclic and polycyclic heteroaryl groups, wherein each Ar ¹ may contain one to five of said heteroaryl groups each of which may be fused or linked;

each Ar ² is independently selected from aryl groups containing more than 6 atoms excluding H; and the fullerene ball represents a fullerene selected from the group consisting of C ₆₀, C ₇₀, and C ₈₄ fullerene.
The composition of claim 11, wherein the non-fullerene acceptor is selected from the group consisting of:

each R ₅ is independently selected from the group consisting of Ar, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, and (C ₃-C ₄₀) cyclic alkyl, wherein one or more non-adjacent C atoms are optionally replaced by –O–, –S–, –C (O) –, –C (O) –O–, –O– C (O) –, –O–C (O) –O–, –CR ⁰=CR ⁰⁰–, or –C≡C–, wherein one or more H atoms are optionally replaced by F, Cl, Br, I, or CN, and wherein R ⁰ and R ⁰⁰ are independently a straight chain, branched, or cyclic alkyl group; or each R ₅ is independently aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl, or heteroaryloxycarbonyl having 4 to 30 ring atoms.
The composition of claim 11, wherein the composition has a power conversion efficiency of about 5.9 %to about 12%.
The composition of claim 11, wherein the non-fullerene acceptor is selected from the group consisting of:

wherein each R ₆ is (C ₁-C ₁₄) alkyl;

R ₇ is -CH ₂CH (R ₉) (R ₁₀) , wherein R ₉ and R ₁₀ are independently (C ₁-C ₂₀) alkyl; and

R ₈ is (C ₁-C ₁₄) alkyl.
The composition of claim 15, wherein R ₁ is H, F, Cl, Br, I, CN, (C ₁-C ₄₀) straight chain alkyl, (C ₃-C ₄₀) branched chain alkyl, (C ₃-C ₄₀) cycloalkyl, aryl, or heteroaryl.
The composition of claim 11, wherein the donor-acceptor conjugated polymer is selected from the group consisting of:

the non-fullerene acceptor is selected from the group consisting of:

wherein m is a whole number selected from 5 to 100.
An organic electronic (OE) device comprising the composition of claim 11.
The OE device of claim 18, characterized in that the OE device is an organic field effect transistor (OFET) device or an organic photovoltaic (OPV) device.
The OE device of claim 19, wherein the OPV device has a power conversion efficiency of about 5.9 %to about 11.2%.