ORGANIC SEMICONDUCTING COMPOUNDS AND DEVICES GENERATED

THEREFROM

Cross Reference to Related Applications

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/442,551, filed on February 14, 2011, the disclosure of which is incorporated by reference herein in its entirety.

Background

[0002] Organic electronics can be manufactured inexpensively as compared to conventional silicon-based electronics and suitable for widespread applications including displays, radio- frequency identification (RFID) tags, chemo-/biosensors, memory devices, solar cells, photodiodes, etc. Organic semiconductors can be processed at low temperatures and deposited on plastic substrates to enable light- weight, flexible, and ultra-thin electronic devices. However, organic semiconductors, especially solution-processed organic semiconductors, have shown insufficient electronic performance as compared with inorganic semiconductors. For example, the charge carrier mobility of solution-processed organic semiconductors is typically lower than 1 cmVV ^' s, inadequate as channel semiconductor materials in organic thin film transistors (OTFTs) for many target applications. Therefore, there is a need to develop solution-processable organic semiconductors, especially oligomers and polymers, with mobility greater than 1 cmVV ^' s.

Summary

[0003] The present teachings relate to solution-processable organic semiconducting compounds comprising polycyclic aromatic moieties, which can be used as high performance organic semiconductors for OTFTs, organic photovoltaics (OPVs), sensors, and other electronic devices.

[0004] One objective of the present teachings is to develop oligomeric or polymeric semiconductor materials comprising polycyclic aromatic moieties for electronic devices such as OTFTs, OPVs, and sensors.

[0005] Another objective is to develop OTFTs, OPVs, sensors, and other electronic devices comprising organic semiconductors comprising polycyclic aromatic moieties. [0006] The foregoing as well as other features and advantages of the present teachings will be more fully understood from the following figures, description, examples, and claims.

Brief Description of Drawings

[0007] Figure 1 depicts a typical bottom-gate, top-contact OTFT structure.

[0008] Figure 2 depicts a typical bottom-gate, bottom-contact OTFT structure.

[0009] Figure 3 depicts a typical top-gate, bottom-contact OTFT structure.

[0010] Figure 4 depicts a typical top-gate, top-contact OTFT structure.

[0011] Figure 5 illustrates a representative structure of a bulk-heteroj unction organic photovoltaic device (also known as solar cell) which can incorporate one or more compounds of the present teachings as the donor and/or acceptor materials.

[0012] Figure 6 illustrates a representative structure of an organic light-emitting device which can incorporate one or more compounds of the present teachings as electron- transporting and/or emissive and/or hole-transporting materials.

[0013] Figure 7 shows a 300 MHz ^X H NMR spectrum of compound 1 in CDC1 ₃ .

[0014] Figure 8 shows a 300 MHz ^X H NMR spectrum of compound 2 in DMSO-d6.

[0015] Figure 9 shows a 300 MHz ^X H NMR spectrum of compound 3 in CDC1 ₃ .

[0016] Figure 10 shows representative optical absorption spectra of two exemplary compounds of the present teachings (PI, dotted line; P2, solid line) dissolved in CHCI ₃ .

Detailed Description

[0017] The present teachings provide organic semiconductor materials that are prepared from oligomeric or polymeric compounds having one or more pyrazine-fused polycyclic aromatic moieties. Compounds of the present teachings can exhibit semiconductor behavior such as high carrier mobility and/or good current modulation characteristics in a field-effect device, light absorption/charge separation in a photovoltaic device, and/or charge transport/recombination/light emission in a light-emitting device. In addition, the present compounds can possess certain processing advantages such as solution-processability and/or good stability (for example, air stability) in ambient conditions. The compounds of the present teachings can be used to prepare either p-type or n-type semiconductor materials, which in turn can be used to fabricate various organic electronic articles, structures and devices, including field-effect transistors, unipolar circuitries, complementary circuitries, photovoltaic devices, and light emitting devices.

[0018] More specifically, the present teachings relate to oligomeric and polymeric compounds comprising poly cyclic aromatic moieties I or II:

wherein:

X, at each occurrence, independently is O or S;

W, at each occurrence, independently is O, S, or NR ¹ , wherein R ¹ , at each occurrence, independently is hydrogen or a substitution group which can impart improved desirable properties to the compound as a whole. For example, certain substitution groups including one or more electron-withdrawing or electron-donating moieties can modulate the electronic properties of the compound, while substitution groups that include one or more aliphatic chains can improve the solubility of the compound in organic solvents.

[0019] 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 also consist essentially of, or consist of, the recited components, and that the processes of the present teachings also consist essentially of, or consist of, the recited process steps.

[0020] 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 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. [0021] 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.

[0022] 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.

[0023] 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.

[0024] As used herein, an "oligomeric compound" (or "oligomer") or a "polymeric compound" (or "polymer") refers to a molecule including a plurality of one or more repeat units connected by covalent chemical bonds. As used herein, a repeat unit in an oligomeric or polymeric compound must repeat itself at least twice in the oligomeric or polymeric compound. An oligomeric or polymeric compound can be represented by the general formula:

wherein M is the repeat unit or monomer, and the degree of polymerization (n) can range from 2 to greater than 10,000. For example, for oligomeric compounds, the degree of polymerization can range from 2 to 9; and for polymeric compounds, the degree of polymerization can range from 10 to about 10,000. The oligomeric or polymeric compound can have only one type of repeat unit as well as two or more types of different repeat units. When a polymeric compound has only one type of repeat unit, it can be referred to as a homopolymer. When a polymeric compound has two or more types of different repeat units, the term "copolymer" or "copolymeric compound" can be used instead. The oligomeric or polymeric compound can be linear or branched. Branched polymers can include dendritic polymers, such as dendronized polymers, hyperbranched polymers, brush polymers (also called bottle-brushes), and the like. Unless specified otherwise, the assembly of the repeat 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, the general formula:

can be used to represent a copolymer of M ^a and M ^b having x mole fraction of M ^a andy mole fraction of M ^b in the copolymer, where the manner in which comonomers M ^a and M ^b is repeated can be alternating, random, regiorandom, regioregular, or in blocks.

[0025] As used herein, a "cyclic moiety" can include one or more (e.g., 1-6) carbocyclic or heterocyclic rings. The cyclic moiety can be a cycloalkyl group, a heterocycloalkyl group, an aryl group, or a heteroaryl group (i.e., can include only saturated bonds, or can include one or more unsaturated bonds regardless of aromaticity), each including, for example, 3-24 ring atoms and can be optionally substituted as described herein. In embodiments where the cyclic moiety is a "monocyclic moiety," the "monocyclic moiety" can include a 3-14 membered aromatic or non-aromatic, carbocyclic or heterocyclic ring. A monocyclic moiety can include, for example, a phenyl group or a 5- or 6-membered heteroaryl group, each of which can be optionally substituted as described herein. In embodiments where the cyclic moiety is a "polycyclic moiety," the "polycyclic moiety" can include two or more rings fused to each other (i.e., sharing a common bond) and/or connected to each other via a spiro atom, or one or more bridged atoms. A polycyclic moiety can include an 8-24 membered aromatic or non-aromatic, carbocyclic or heterocyclic ring, such as a C _8- 24 aryl group or an 8-24 membered heteroaryl group, each of which can be optionally substituted as described herein.

[0026] As used herein, "halo" or "halogen" refers to fluoro, chloro, bromo, and iodo.

[0027] As used herein, "oxo" refers to a double-bonded oxygen (i.e., =0).

[0028] 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., ^-propyl and wopropyl), butyl (e.g., w-butyl, wo-butyl, sec-butyl, ferf-butyl), pentyl groups (e.g., w-pentyl, wopentyl, weopentyl), hexyl groups, and the like. In various embodiments, an alkyl group can have 1 to 40 carbon atoms (i.e., Ci-40 alkyl group), for example, 1-20 carbon atoms (i.e., Ci-20 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., « -propyl and wopropyl), and butyl groups (e.g., « -butyl, wobutyl, sec- butyl, ferf-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.

[0029] As used herein, "haloalkyl" refers to an alkyl group having one or more halogen substituents. At various embodiments, a haloalkyl group can have 1 to 40 carbon atoms (i.e., Ci-40 haloalkyl group), for example, 1 to 20 carbon atoms (i.e., C _1-2 o haloalkyl group).

Examples of haloalkyl groups include CF ₃ , C ₂ F ₅ , CHF ₂ , CH ₂ F, CC1 ₃ , CHC1 ₂ , CH ₂ C1, C ₂ C1 ₅ , and the like. Perhaloalkyl groups, i.e., alkyl groups where all of the hydrogen atoms are replaced with halogen atoms (e.g. , CF ₃ and C ₂ F ₅ ), are included within the definition of "haloalkyl." For example, a C _1-4 o haloalkyl group can have the formula -C ₃ H _2s+ i _-t X ⁰ t, where X°, at each occurrence, is F, CI, Br or I, s is an integer in the range of 1 to 40, and t is an integer in the range of 1 to 81, provided that t is less than or equal to 2s+l . Haloalkyl groups that are not perhaloalkyl groups can be substituted as described herein.

[0030] As used herein, "alkoxy" refers to -O-alkyl group. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy (e.g., n-propoxy and isopropoxy), t- butoxy, pentoxy, hexoxy groups, and the like. The alkyl group in the

-O-alkyl group can be substituted as described herein.

[0031] As used herein, "alkylthio" refers to an -S-alkyl group (which, in some cases, can be expressed as -S(0) _w -alkyl, wherein w is 0). Examples of alkylthio groups include, but are not limited to, methylthio, ethylthio, propylthio (e.g. , n-propylthio and isopropylthio), t- butylthio, pentylthio, hexylthio groups, and the like. The alkyl group in the -S-alkyl group can be substituted as described herein.

[0032] As used herein, "arylalkyl" refers to an -alkyl-aryl group, where the arylalkyl group is covalently linked to the defined chemical structure via the alkyl group. An arylalkyl group is within the definition of a -Y-C _6- i4 aryl group, where Y is defined as a divalent alky group that can be optionally substituted as described herein. An example of an arylalkyl group is a benzyl group (-CH ₂ -C ₆ H ₅ ). An arylalkyl group can be optionally substituted, i.e., the aryl group and/or the alkyl group, can be substituted as disclosed herein.

[0033] As used herein, "alkenyl" refers to a straight-chain or branched 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- 4o alkenyl group), for example, 2 to 20 carbon atoms (i.e., C ₂ - ₂ o 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.

[0034] As used herein, "alkynyl" refers to a straight-chain or branched alkyl group having one or more triple carbon-carbon bonds. Examples of alkynyl groups include ethynyl, propynyl, butynyl, pentynyl, hexynyl, and the like. The one or more triple carbon-carbon bonds can be internal (such as in 2-butyne) or terminal (such as in 1-butyne). In various embodiments, an alkynyl group can have 2 to 40 carbon atoms (i.e., C _2- 4o alkynyl group), for example, 2 to 20 carbon atoms (i.e., C _2-20 alkynyl group). In some embodiments, alkynyl groups can be substituted as described herein. An alkynyl group is generally not substituted with another alkynyl group, an alkyl group, or an alkenyl group.

[0035] As used herein, "cycloalkyl" refers to a non-aromatic carbocyclic group including cyclized alkyl, alkenyl, and alkynyl groups. In various embodiments, a cycloalkyl group can have 3 to 24 carbon atoms, for example, 3 to 20 carbon atoms (e.g., C _3-14 cycloalkyl group). A cycloalkyl group can be monocyclic (e.g., cyclohexyl) or polycyclic (e.g., containing fused, bridged, and/or spiro ring systems), where the carbon atoms are located inside or outside of the ring system. Any suitable ring position of the cycloalkyl group can be covalently linked to the defined chemical structure. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl, cyclohexenyl, cyclohexadienyl, cycloheptatrienyl, norbornyl, norpinyl, norcaryl, adamantyl, and spiro[4.5]decanyl groups, as well as their homologs, isomers, and the like. In some embodiments, cycloalkyl groups can be substituted as described herein.

[0036] 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.

[0037] As used herein, "cycloheteroalkyl" refers to a non-aromatic cycloalkyl group that contains at least one ring heteroatom selected from O, S, Se, N, P, and Si (e.g., O, S, and N), and optionally contains one or more double or triple bonds. A cycloheteroalkyl group can have 3 to 24 ring atoms, for example, 3 to 20 ring atoms (e.g., 3-14 membered

cycloheteroalkyl group). One or more N, P, S, or Se atoms (e.g., N or S) in a

cycloheteroalkyl ring may be oxidized (e.g., morpholine N-oxide, thiomorpholine S-oxide, thiomorpholine S,S-dioxide). In some embodiments, nitrogen or phosphorus atoms of cycloheteroalkyl groups can bear a substituent, for example, a hydrogen atom, an alkyl group, or other substituents as described herein. Cycloheteroalkyl groups can also contain one or more oxo groups, such as oxopiperidyl, oxooxazolidyl, dioxo-(lH,3H)-pyrimidyl, oxo-2(lH)- pyridyl, and the like. Examples of cycloheteroalkyl groups include, among others, morpholinyl, thiomorpholinyl, pyranyl, imidazolidinyl, imidazolinyl, oxazolidinyl, pyrazolidinyl, pyrazolinyl, pyrrolidinyl, pyrrolinyl, tetrahydrofuranyl, tetrahydrothiophenyl, piperidinyl, piperazinyl, and the like. In some embodiments, cycloheteroalkyl groups can be substituted as described herein.

[0038] As used herein, "aryl" refers to an aromatic monocyclic hydrocarbon ring system or a poly cyclic 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., Ce-20 aryl group), which can include multiple fused rings. In some embodiments, a poly cyclic 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 (bi cyclic), 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. , -CeF 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. [0039] 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 those having two or more heteroaryl rings fused together, as well as those having at least one monocyclic heteroaryl ring 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 24 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-0 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, pyrimidyl, pyridazinyl, pyrazinyl, triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl, thiazolyl, thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl, benzofuryl, benzothienyl, quinolyl, 2-methylquinolyl, isoquinolyl, quinoxalyl, quinazolyl, benzotriazolyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl, cinnolinyl, lH-indazolyl, 2H-indazolyl, indolizinyl, isobenzofuyl, naphthyridinyl, phthalazinyl, pteridinyl, purinyl, oxazolopyridinyl, thiazolopyridinyl, imidazopyridinyl, furopyridinyl, thienopyridinyl, pyridopyrimidinyl, pyridopyrazinyl, pyridopyridazinyl, thienothiazolyl, thienoxazolyl, thienoimidazolyl groups, and the like. Further examples of heteroaryl groups include 4,5,6,7- tetrahydroindolyl, tetrahydroquinolinyl, benzothienopyridinyl, benzofuropyridinyl groups, and the like. In some embodiments, heteroaryl groups can be substituted as described herein.

[0040] Compounds of the present teachings can include a "divalent group" defined herein as a linking group capable of forming a covalent bond with two other moieties. For example, compounds of the present teachings can include a divalent C _1-2 o alkyl group (e.g., a methylene group), a divalent C2-2 ₀ alkenyl group (e.g., a vinylyl group), a divalent C2-2 ₀ alkynyl group (e.g., an ethynylyl group), a divalent C ₆ -u aryl group (e.g., a phenylyl group); a divalent 3-14 membered cycloheteroalkyl group (e.g., a pyrrolidylyl), and/or a divalent 5-14 membered heteroaryl group (e.g., a thienylyl group). Generally, a chemical group (e.g., -AT-) is understood to be divalent by the inclusion of the two bonds before and after the group.

[0041] The electron-donating or electron-withdrawing properties of several hundred of the most common substituents, reflecting all common classes of substituents have been determined, quantified, and published. The most common quantification of electron-donating and electron- withdrawing properties is in terms of Hammett σ values. Hydrogen has a Hammett σ value of zero, while other substituents have Hammett σ values that increase positively or negatively in direct relation to their electron-withdrawing or electron-donating characteristics. Substituents with negative Hammett σ values are considered electron- donating, while those with positive Hammett σ values are considered electron-withdrawing. See Lange's Handbook of Chemistry, 12th ed., McGraw Hill, 1979, Table 3-12, pp. 3-134 to 3-138, which lists Hammett σ values for a large number of commonly encountered substituents and is incorporated by reference herein.

[0042] It should be understood that the term "electron-accepting group" can be used synonymously herein with "electron acceptor" and "electron-withdrawing group". In particular, an "electron-withdrawing group" ("EWG") or an "electron-accepting group" or an "electron-acceptor" refers to a functional group that draws electrons to itself more than a hydrogen atom would if it occupied the same position in a molecule. Examples of electron- withdrawing groups include, but are not limited to, halogen or halo (e.g., F, CI, Br, I), -N0 ₂ , -CN, -NC, -S(R°) ₂ ⁺ , -N(R°) ₃ ⁺ , -SO3H, -SO2R ⁰ , -SO3R ⁰ , -SO2NHR ⁰ , -S0 ₂ N(R°) ₂ , -COOH, -COR", -COOiT, -CONHR , -CON(R ^u ) ₂ , Ci _-40 haloalkyl groups, C ₆ . _u aryl groups, and 5-14 membered electron-poor heteroaryl groups; where R° is a C _1-2 o alkyl group, a C2-20 alkenyl group, a C2-20 alkynyl group, a C _1-2 o haloalkyl group, a C _1-2 o alkoxy group, a C6-i ₄ aryl group, a C3-14 cycloalkyl group, a 3-14 membered cycloheteroalkyl group, and a 5-14 membered heteroaryl group, each of which can be optionally substituted as described herein. For example, each of the C _1-2 o alkyl group, the C2-20 alkenyl group, the C2-20 alkynyl group, the Ci-20 haloalkyl group, the C _1-2 o alkoxy group, the C6-i ₄ aryl group, the C _3-14 cycloalkyl group, the 3-14 membered cycloheteroalkyl group, and the 5-14 membered heteroaryl group can be optionally substituted with 1-5 small electron- withdrawing groups such as F, CI, Br, -N0 ₂ , -CN, -NC, -S(R ⁰ ) ₂ ⁺ ,-N(R ⁰ ) ₃ ⁺ , -S0 ₃ H, -S0 ₂ R°, -S0 ₃ R°, -S0 ₂ NHR°, -S0 ₂ N(R°) ₂ , -COOH, -COR ⁰ , -COOR°,-CONHR°, and -CON(R°) ₂ .

[0043] It should be understood that the term "electron-donating group" can be used synonymously herein with "electron donor". In particular, an "electron-donating group" or an "electron-donor" refers to a functional group that donates electrons to a neighboring atom more than a hydrogen atom would if it occupied the same position in a molecule. Examples of electron-donating groups include -OH, -OR ⁰ , -NH ₂ , -NHR°, -N(R°) ₂ , and 5-14 membered electron-rich heteroaryl groups, where R° is a C _1-2 o alkyl group, a C2-20 alkenyl group, a C2-20 alkynyl group, a C6-i ₄ aryl group, or a C _3-14 cycloalkyl group.

[0044] Various unsubstituted heteroaryl groups can be described as electron-rich (or π- excessive) or electron-poor (or π-deficient). Such classification is based on the average electron density on each ring atom as compared to that of a carbon atom in benzene.

Examples of electron-rich systems include 5 -membered heteroaryl groups having one heteroatom such as furan, pyrrole, and thiophene; and their benzofused counterparts such as benzofuran, benzopyrrole, and benzothiophene. Examples of electron-poor systems include 6-membered heteroaryl groups having one or more heteroatoms such as pyridine, pyrazine, pyridazine, and pyrimidine; as well as their benzofused counterparts such as quinoline, isoquinoline, quinoxaline, cinnoline, phthalazine, naphthyridine, quinazoline, phenanthridine, acridine, and purine. Mixed heteroaromatic rings can belong to either class depending on the type, number, and position of the one or more heteroatom(s) in the ring. See Katritzky, A.R and Lagowski, J.M., Heterocyclic Chemistry (John Wiley & Sons, New York, 1960).

[0045] At various places in the present specification, substituents are disclosed in groups or in ranges. It is specifically intended that the description include each and every individual subcombination of the members of such groups and ranges. For example, the term "Ci _-6 alkyl" is specifically intended to individually disclose C _1; C ₂ , C ₃ , C ₄ , C5, Ce, i-Ce, C1-C5, C1-C4, Ci-C ₃ , C1-C2, C ₂ -C6, C2-C5, C2-C4, C2-C ₃ , C ₃ -C6, C ₃ -C5, C ₃ -C4, C4-C6, C4-C5, and C5-C6 alkyl. By way of other examples, an integer in the range of 0 to 40 is specifically intended to individually disclose 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38, 39, and 40, and an integer in the range of 1 to 20 is specifically intended to individually disclose 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, and 20. Additional examples include that the phrase "optionally substituted with 1 -5 substituents" is specifically intended to individually disclose a chemical group that can include 0, 1, 2, 3, 4, 5, 0-5, 0-4, 0-3, 0-2, 0-1, 1-5, 1-4, 1 -3, 1 -2, 2-5, 2-4, 2-3, 3-5, 3-4, and 4-5 substituents.

[0046] Compounds described herein can contain an asymmetric atom (also referred as a chiral center) and some of the compounds can contain two or more asymmetric atoms or centers, which can thus give rise to optical isomers (enantiomers) and diastereomers

(geometric isomers). The present teachings include such optical isomers and diastereomers, including their respective resolved enantiomerically or diastereomerically pure isomers (e.g., (+) or (-) stereoisomer) and their racemic mixtures, as well as other mixtures of the enantiomers and diastereomers. In some embodiments, optical isomers can be obtained in enantiomerically enriched or pure form by standard procedures known to those skilled in the art, which include, for example, chiral separation, diastereomeric salt formation, kinetic resolution, and asymmetric synthesis. The present teachings also encompass cis- and trans- isomers of compounds containing alkenyl moieties (e.g. , alkenes, azo, and imines). It also should be understood that the compounds of the present teachings encompass all possible regioisomers in pure form and mixtures thereof. In some embodiments, the preparation of the present compounds can include separating such isomers using standard separation procedures known to those skilled in the art, for example, by using one or more of column

chromatography, thin-layer chromatography, simulated moving-bed chromatography, and high-performance liquid chromatography. However, mixtures of regioisomers can be used similarly to the uses of each individual regioisomer of the present teachings as described herein and/or known by a skilled artisan.

[0047] It is specifically contemplated that the depiction of one regioisomer includes any other regioisomers and any regioisomeric mixtures unless specifically stated otherwise. [0048] As used herein, a "leaving group" ("LG") refers to a charged or uncharged atom (or group of atoms) that can be displaced as a stable species as a result of, for example, a substitution or elimination reaction. Examples of leaving groups include, but are not limited to, halogen (e.g., CI, Br, I), azide (N ₃ ), thiocyanate (SCN), nitro (N0 ₂ ), cyanate (CN), water (H ₂ 0), ammonia (NH ₃ ), and sulfonate groups (e.g., OS0 ₂ -R, wherein R can be a Ci-io alkyl group or a C6-i ₄ aryl group each optionally substituted with 1-4 groups independently selected from a Ci-io alkyl group and an electron-withdrawing group) such as tosylate

(toluenesulfonate, OTs), mesylate (methanesulfonate, OMs), brosylate

(p-bromobenzenesulfonate, OBs), nosylate (4-nitrobenzenesulfonate, ONs), and triflate (trifluoromethanesulfonate, OTf).

[0049] As used herein, a "p-type semiconductor material" or a "p-type semiconductor" refers to a 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 /V s. In the case of field-effect devices, a p-type semiconductor can also exhibit a current on/off ratio of greater than about 10.

[0050] As used herein, an "n-type semiconductor material" or an "n-type semiconductor" refers to a 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 /V s. In the case of field-effect devices, an n-type semiconductor can also exhibit a current on/off ratio of greater than about 10.

[0051] 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 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.

[0052] As used herein, fill factor (FF) is the ratio (given as a percentage) of the actual maximum obtainable power, (P _m or V _mp * J _mp ), to the theoretical (not actually obtainable) power, (J _so x V _oc ). Accordingly, FF can be determined using the equation:

FF = (V _mp * J _mp ) / (J _sc * V _oc ) where J _mp and V _mp represent the current density and voltage at the maximum power point (P _m ), respectively, this point being obtained by varying the resistance in the circuit until J * V is at its greatest value; and J _so and V _oc 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.

[0053] As used herein, the open-circuit voltage (V _oc ) is the difference in the electrical potentials between the anode and the cathode of a device when there is no external load connected.

[0054] 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 (P _m ) by the input light irradiance (E, in W/m ² ) under standard test conditions (STC) and the surface area of the solar cell (A ₀ in m ² ). STC typically refers to a temperature of 25°C and an irradiance of 1000 W/m ² with an air mass 1.5 (AM 1.5) spectrum.

[0055] 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.

[0056] Throughout the specification, structures may or may not be presented with chemical names. Where any question arises as to nomenclature, the structure prevails.

[0057] In one aspect, the present teachings relate to oligomeric and polymeric

semiconducting compounds, as well as the use of these compounds in electronic, optoelectronic, or optical devices. More specifically, these compounds can include a repeat unit having a pyrazine-fused poly cyclic aromatic moiety selected from:

wherein R ¹ , at each occurrence, independently is hydrogen or an optionally substituted hydrocarbon with 1 to 40 carbon atoms. For example, R ¹ , at each occurrence, independently can be selected from H, a C _1- o alkyl group, a C2-40 alkenyl group, a C2-40 alkynyl group, a Ci_ 40 haloalkyl group, wherein each of the C _1-2 o alkyl group, the C2-20 alkenyl group, the C2-20 alkynyl group, and the C _1-2 o haloalkyl group optionally can be substituted with 1-5 substituents independently selected from a halogen, -CN, NO2, OH, -NH ₂ , -NH(C _1-2 o alkyl), -N(Ci-2o alkyl) ₂ , -S(0) ₂ OH, -CHO, -C(O)-Ci _-20 alkyl, -C(0)OH, -C(O)-OCi _-20 alkyl, -C(0)NH ₂ , -C(0)NH-Ci-2o alkyl, -C(O)N(Ci _-20 alkyl) ₂ , -OC1.20 alkyl, -SC1.20 alkyl, -S1H3, -SiH(Ci.2o alkyl) ₂ , -SiH ₂ (Ci _-2 o alkyl), -Si(Ci _-20 alkyl) ₃ and -(OCR' ₂ CR" ₂ )t-, wherein R and R", at each occurrence, independently are H or F, and t is an integer in the range of 1 to 20; and a C6-i ₄ aryl group optionally substituted with 1-5 substituents independently selected from a halogen, -CN, N0 ₂ , OH, -NH ₂ , -NH(Ci _-20 alkyl), -N(Ci _-20 alkyl) ₂ , -S(0) ₂ OH, -CHO, -C(O)-C _1-20 alkyl, -C(0)OH, -C(O)-OC _1-20 alkyl, -C(0)NH ₂ , -C(O)NH-C _1-20 alkyl, -C(0)N(Ci-2o alkyl) ₂ , -OC1.20 alkyl, -SCi-20 alkyl, -S1H3, -SiH(Ci _-20 alkyl) ₂ , -SiH ₂ (Ci _-2 o alkyl), -Si(C _1-2 o alkyl) ₃ , a C _1-2 o alkyl group, a C2-20 alkenyl group, a C2-20 alkynyl group, and a Ci-20 haloalkyl group.

[0058] For example, in certain embodiments, R ¹ , at each occurrence, independently can be a linear or branched C _3-4 o alkyl group, examples of which include an n-hexyl group, an n-octyl group, an n-dodecyl group, a 1 -methylpropyl group, a 1 -methylbutyl group, a 1- methylpentyl group, a 1 -methylhexyl group, a 1-ethylpropyl group, a 1 -ethyl butyl group, a 1,3-dimethylbutyl group, a 2-ethylhexyl group, a 2-hexyloctyl group, a 2-octyldodecyl group, and a 2-decyltetradecyl group. In certain embodiments, R ¹ , at each occurrence,

independently can be a linear or branched C ₃ -40 alkenyl group (such as the linear or branched C ₃ -40 alkyl groups specified above but with one or more saturated bonds replaced by unsaturated bonds). In particular embodiments, R ¹ , at each occurrence, independently can be a branched C ₃ -20 alkyl group or a branched C ₃ -20 alkenyl group. In certain embodiments, R ¹ , at each occurrence, independently can be a linear or branched C _3-4 o haloalkyl group (such as the linear or branched C3-40 alkyl groups specified above but with one or more hydrogen atoms replaced by a halide such as F or CI).

[0059] In certain embodiments, R ¹ , at each occurrence, independently can be a linear or branched C _6- 4o alkyl, alkenyl, or haloalkyl group, an arylalkyl group (e.g., a benzyl group) substituted with a linear or branched Ce-40 alkyl, alkenyl, or haloalkyl group, an aryl group (e.g., a phenyl group) substituted with a linear or branched C6-40 alkyl, alkenyl, or haloalkyl group, or a biaryl group (e.g., a biphenyl group) substituted with a linear or branched C6-40 alkyl, alkenyl, or haloalkyl group, wherein each of the aryl groups optionally can be substituted with 1-5 halo groups (e.g., F). In some embodiments, each R ¹ can be a biaryl group wherein the two aryl groups are covalently linked via a linker. For example, the linker can be a divalent C _{1 -4} o alkyl group wherein one or more non-adjacent CH ₂ groups can be optionally replaced by -0-, -S-, or -Se-, provided that O, S, and/or Se atoms are not linked directly to one another. The linker can include other heteroatoms and/or functional groups as described herein.

[0060] In certain embodiments, each R ¹ independently can be selected from

-(CH ₂ CH ₂ 0)tR ^e , -(CF ₂ CF ₂ 0) _t R ^e , -(CH ₂ CF ₂ 0) _t R ^e , and -(CF ₂ CH ₂ 0) _t R ^e ; where R ^e can be selected from H, a C _{1 -4} o alkyl group, and a C _{1 -4} o haloalkyl group; and t can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0061] In certain embodiments, each R ¹ independently can be a C6-i ₄ aryl group or a 5-14 membered heteroaryl group, each of which optionally can be substituted with 1-2 groups independently selected from a halogen, CN, oxo, =C(CN) ₂ , a C _{1 -4} o alkyl group, a C _{1 -} o haloalkyl group, a C _{1 -4} o alkoxy group, and a C _{1 -4} o alkylthio group. For example, each R ¹ independently can be a thienyl group or an 8-14 membered thienyl-fused heteroaryl group, each of which can be optionally substituted as described herein.

[0062] More generally, each R ¹ independently can be selected from H, a C _{1 -4} o alkyl group, a C _2- 4o alkenyl group, a C _2- 4o alkynyl group, a C _{1 -4} o haloalkyl group, and 1-4 cyclic moieties, wherein:

each of the C _{1 -4} o alkyl group, the C _2- 4o alkenyl group, the C _2- 4o alkynyl group, and the Ci-40 haloalkyl group optionally can be substituted with 1-10 substituents independently selected from a halogen, -CN, N0 ₂ , OH, -NH ₂ , -NH(Ci _-20 alkyl), -N(Ci _-20 alkyl) ₂ ,

-S(0) ₂ OH, -CHO, -C(O)-Ci _-20 alkyl, -C(0)OH, -C(O)-OCi _-20 alkyl, -C(0)NH ₂ , -C(O)NH-C _1-20 alkyl, -C(O)N(C _1-20 alkyl) ₂ , -OC _1-20 alkyl, -(OCR' ₂ CR" ₂ ) _t -, -SiH ₃ ,

-SiH(Ci _-20 alkyl) ₂ , -SiH ₂ (Ci _-20 alkyl), and -Si(C _1-20 alkyl) ₃ , where R' and R", at each occurrence, independently are H or F, and t is an integer in the range of 1 to 20;

each of the Ci-40 alkyl group, the C _2- 4o alkenyl group, the C _2- 4o alkynyl group, and the Ci-40 haloalkyl group can be covalently bonded to the imide nitrogen atom via an optional linker; and

each of the 1-4 cyclic moieties can be the same or different, can be covalently bonded to each other or the imide nitrogen via an optional linker, and optionally can be substituted with 1-5 substituents independently selected from a halogen, -CN, oxo, N0 ₂ , OH, =C(CN) ₂ , -NH ₂ , -NH(Ci-2o alkyl), -N(Ci _-20 alkyl) ₂ , -S(0) ₂ OH, -CHO, -C(0)OH, -C(O)-Ci _-20 alkyl, -C(O)-OCi _-20 alkyl, -C(0)NH ₂ , -C(O)NH-Ci _-20 alkyl, -C(O)N(Ci _-20 alkyl) ₂ , -S1H3,

-SiH(Ci.2o alkyl) ₂ , -SiH ₂ (Ci _-20 alkyl), -Si(Ci _-20 alkyl) ₃ , -O-Ci-20 alkyl, -(OCR ₂ CR" ₂ ) _t - a Ci _-2 o alkyl group, a C _2-2 o alkenyl group, a C _2-2 o alkynyl group, and a Ci _-2 o haloalkyl group; wherein each of the Ci _-20 alkyl group, the C _2-20 alkenyl group, the C _2-20 alkynyl group, and the Ci _-2 o haloalkyl group optionally can be substituted with 1-5 substituents independently selected from a halogen, -CN, N0 ₂ , OH, -NH ₂ , -NH(Ci _-6 alkyl), -N(Ci _-6 alkyl) ₂ , -S(0) ₂ OH, -CHO, -C(0)-Ci-6 alkyl, -C(0)OH, -C(0)-OCi _-6 alkyl, -C(0)NH ₂ , -C(0)NH-Ci _-6 alkyl, -C(0)N(Ci-6 alkyl) ₂ , -OCi _-6 alkyl, -SiH ₃ , -SiH(Ci _-6 alkyl) ₂ , -SiH ₂ (Ci _-6 alkyl), and

-Si(Ci_6 alkyl) ₃ , where R', R", and t are as defined herein.

[0063] To further illustrate, in certain embodiments, R ¹ , at each occurrence, independently can be selected from H or -L-R ^a , where R ^a is selected from a Ci-40 alkyl group, a C _2- 4o alkenyl group, a C _2- 4o alkynyl group, and a Ci-40 haloalkyl group, each of which can be optionally substituted with 1-10 substituents independently selected from a halogen, -CN, N0 ₂ , OH, -NH ₂ , -NH(Ci-2o alkyl), -N(Ci _-20 alkyl) ₂ , -S(0) ₂ OH, -CHO, -C(O)-Ci _-20 alkyl, -C(0)OH, -C(O)-OCi _-20 alkyl, -C(0)NH ₂ , -C(O)NH-Ci _-20 alkyl, -C(O)N(Ci _-20 alkyl) ₂ , -OCi-20 alkyl, -(OCR ₂ CR" ₂ ) _t -, -SiH ₃ , -SiH(Ci _-20 alkyl) ₂ , -SiH ₂ (Ci _-20 alkyl), and

-Si(Ci _-2 o alkyl) ₃ , where R, R", and t are as defined herein; and L is a covalent bond or a linker comprising one or more heteroatoms. For example, L can be a linker selected from -Y-[0-Y] _t - (e g, -Y-(OCR ₂ CR" ₂ ) _t -), -[Y-0] _t -Y- (e g, -(CR ₂ CR" ₂ 0) _t -Y-),

-Y-[S(0) _w ]-Y- -Y-C(0)-Y- -Y-[NR ^c C(0)]-Y- -Y-[C(0)NR ^c ]-, -Y-NR -Y- -Y-[SiR ^c ₂ ]-Y-, where Y, at each occurrence, independently is selected from a divalent Ci _-2 o alkyl group, a divalent C _2-2 o alkenyl group, a divalent C _2-2 o haloalkyl group, and a covalent bond; R ^c is selected from H, a Ci-6 alkyl group, a C6-14 aryl group, and a -Ci-6 alkyl-C6-i4 aryl group; w is 0, 1, or 2, and R', R", and t are as defined herein. In some embodiments, each R ¹ independently can be selected from H, a C3-40 alkyl group, a C4-40 alkenyl group, a C4-40 alkynyl group, and a C3-40 haloalkyl group, where each of these groups can be linear or branched, and can be optionally substituted as described herein.

[0064] In other embodiments, each R ¹ independently can include one or more cyclic moieties. For example, each R ¹ independently can be selected from -L'-Cy ¹ ,

-L'-Cy -L'-Cy ² , -L'-Cy -L'-Cy^Cy ² , -L'-Cy -Cy ¹ , -L'-Cy -Cy -L'-Cy ² ,

-L'-Cy -Cy -L'-Cy^Cy ² , -L'-Cy -L-R ³ , -L'-Cy -L'-Cy^L-R ³ ,

-L'-Cy -L'-Cy^Cy^L-R ³ , -L'-Cy -Cy -L-R ³ , and -L'-Cy -Cy -L'-Cy^L-R ³ ;

wherein:

Cy ¹ and Cy ² , at each occurrence, independently are selected from a C6-i ₄ aryl group, a 5-14 membered heteroaryl group, a C _3-14 cycloalkyl group, and a 3-14 membered cycloheteroalkyl group, each of which can be optionally substituted with 1-5 substituents independently selected from a halogen, -CN, oxo, =C(CN) ₂ , a Ci-6 alkyl group, a Ci-6 alkoxy group, and a Ci-6 haloalkyl group;

L', at each occurrence, independently is a covalent bond or a linker selected from

-Y-[0-Y] _t - (e g, -Y-(OCR' ₂ CR" ₂ )t-), -[Y-0] _t -Y- (e g, -(CR' ₂ CR" ₂ 0) _t -Y-),

-Y-[S(0) _w ]-Y- -Y-C(0)-Y-, -Y-[NR ^c C(0)]-Y-, -Y-[C(0)NR ^c ]-, -Y-NR -Y- -Y-[SiR ^c ₂ ]-Y-, a divalent C _{1 -2} o alkyl group, a divalent C _2-2 o alkenyl group, and a divalent C _2- 20 haloalkyl group, where Y, R, R", R ^c , t and w are as defined above;

R ^a is selected from a C _{1 -} o alkyl group, a C _2- 4o alkenyl group, a C _2- 4o alkynyl group, and a Ci_ 40 haloalkyl group, each of which can be optionally substituted with 1-10 substituents independently selected from a halogen, -CN, N0 ₂ , OH, -NH ₂ , -NH(C _{1 -2} o alkyl), -N(C _{1 -2} o alkyl) ₂ , -S(0) ₂ OH, -CHO, -C(O)-Ci _-20 alkyl, -C(0)OH, -C(O)-OCi _-20 alkyl, -C(0)NH ₂ , -C(0)NH-Ci.2o alkyl, -C(O)N(Ci _-20 alkyl) ₂ , -OCi _-20 alkyl, -(OCR ₂ CR" ₂ ) _t -, -SiH ₃ ,

-SiH(Ci _-20 alkyl) ₂ , -SiH ₂ (Ci _-20 alkyl), and

-Si(Ci _-2 o alkyl) ₃ , where R, R", and t are as defined herein.

[0065] Further examples of R ¹ include:

1) linear or branched Ci _-40 alkyl groups and C _2-40 alkenyl groups such as:

In various embodiments, each R ¹ can be the same.

[0066] In various embodiments, the present oligomeric or polymeric compounds can have a repeat unit (M ¹ ) represented by the formula (IA):

(IA)

wherein W is O, S, or NR ¹ , where R ¹ is as defined herein; Ar ¹ , at each occurrence, independently can be a ji-conjugated moiety, m, at each occurrence, independently can be 0, 1, 2, 3, 4, 5 or 6; and the degree of polymerization (n) can range from 2 to about 1,000,000. In various embodiments, the degree of polymerization (n) can range from 2 to about 10,000, from 3 to about 10,000, from 4 to about 10,000, from 5 to about 10,000, from 8 to about 10,000, or from 10 to about 10,000. For example, for oligomeric compounds, the degree of polymerization can range from 2 to 9; and for polymeric compounds, the degree of polymerization can range from 10 to 10,000.

[0067] In certain embodiments, Ar ¹ , at each occurrence, can be selected from a monocyclic aryl or heteroaryl group, a bicyclic or polycyclic Cs- aryl group, a bicyclic or polycyclic 8- 14 membered heteroaryl group, and a linear conjugated linker, each of which optionally can be substituted with 1-4 groups independently selected from a halogen, CN, oxo, =C(CN) ₂ , a Ci-40 alkyl group, a C _1-4 o haloalkyl group, a C _1-4 o alkoxy group, and a C _1-4 o alkylthio group.

[0068] In particular embodiments, each (Ar ¹ ^ can include one or more optionally substituted monocyclic (5- or 6-membered) (hetero)aryl groups and/or one or more optionally substituted polycyclic (8 to 14-membered) (hetero)aryl groups. For example, (Ar ¹ ^ can include one or more of : a phenyl group, a thienyl group, a furyl group, a pyrrolyl group, an isothiazolyl group, a thiazolyl group, a 1 ,2,4-thiadiazolyl group, a 1,3,4-thiadiazolyl group, a 1 ,2,5-thiadiazolyl group, and a 8 to 14-membered benzo-fused or thienyl-fused (hetero)aryl group, each of which optionally can be substituted with 1-2 groups independently selected from a halogen, CN, oxo, =C(CN) ₂ , a C _1-4 o alkyl group, a C _1-4 o haloalkyl group, a C _1-4 o alkoxy group, and a C _1-4 o alkylthio group. Examples of 8 to 14-membered benzo-fused or thienyl-fused (hetero)aryl group include a naphthyl group, an anthracenyl group, a thienothiophenyl group (e.g., a thieno[3,2-b]thiophen-2-yl group), a benzothienyl group, a benzodithienyl group, a benzothiazolyl group, a benzisothiazolyl group, a benzothiadiazolyl group, and a benzodithiophene-2,6-yl group.

[0069] By way of example, each (Ar ¹ ^ can include one or more of :

where ogen, CN, oxo, =C(CN) ₂ , a C _1-4 o alkyl group, a C _1-4 o haloalkyl group, a C _1-4 o alkoxy group, and a Ci-40 alkylthio group.

[0070] To further illustrate, in embodiments where the repeat unit includes two or more different Ar ¹ groups, the Ar ¹ groups can include different conjugated cyclic moieties and/or differently substituted conjugated cyclic moieties (for example, including substituted or unsubstituted moieties, and/or moieties having different substitution groups).

[0071] In certain embodiments, Ar ¹ , at each occurrence, can include a linear conjugated linker Z, where Z can be a divalent ethenyl group (i.e., having one double bond), a divalent ethynyl group (i.e., having one tripe bond), a C _4-4 o 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 is as defined herein. In certain embodiments, Z can be selected from

CN

CN

-N .

CN ^N and

[0072] To illustrate, Ar ¹ can be selected from, but not restricted to, the following structures and a combination of two or more of the following structures:

wherein each structure can be substituted with one or more suitable groups independently selected from optionally substituted hydrocarbon with 1 to 40 carbon atoms (such as, for example, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, alkoxy, and substituted alkoxy), cyano (CN), nitro, and halogen, or any other suitable group;

R, at each occurrence, independently is hydrogen or an optionally substituted hydrocarbon with 1 to 40 carbon atoms (such as, for example, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, alkoxy, and substituted alkoxy), or any other suitable group.

[0073] Representative examples of the present compounds having a repeat unit (M ¹ ) represented by the formula (IA), where Ar ¹ is an optionally substituted 8 to 14-membered benzo-fused or thienyl-fused (hetero)aryl group can include:

wherein R ⁴ , at each occurrence, independently is selected from H, F, CI, CN, a C _1-4 o alkyl group, a Ci-40 haloalkyl group, a C _1-4 o alkoxy group, and a C _1-4 o alkylthio group; R ⁷ , at each occurrence, independently is H, halogen, CN, a C _1-4 o alkyl group, a C _1- o alkoxy group, a Ci-40 alkylthio group, a C _1- o haloalkyl group, a C6-i ₄ aryl group optionally substituted with 1-2 Ci-40 alkyl groups, C _1-4 o alkoxy groups, C _1-4 o alkylthio groups, or C _1-4 o haloalkyl groups, a 5-14 heteroaryl group optionally substituted with 1-2 C _1- o alkyl groups, C _1-4 o alkoxy groups, Ci-40 alkylthio groups, or Ci _-40 haloalkyl groups, -(OCH ₂ CH ₂ ) _t OR ^e , -(OCF ₂ CF ₂ ) _t OR ^e , -(OCH ₂ CF ₂ ) _t OR ^e , -(OCF ₂ CH ₂ ) _t OR ^e , -(CH ₂ CH ₂ 0) _t -R ^e , -(CF ₂ CF ₂ 0) _t R ^e , -(CH ₂ CF ₂ 0) _t R ^e , or - (CF ₂ CH ₂ 0) _t R ^e , wherein t is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and R ^e is a Ci _-20 alkyl group or a C _1-2 o haloalkyl group; and W is as defined herein.

[0074] In particular embodiments, the present oligomeric or polymeric compounds can have a repeat unit (M ¹ ) represented by the formula (IB):

(IB)

wherein W is as defined herein; Ar ² is an optionally substituted monocyclic (5- or 6- membered) (hetero)aryl groups; and m' is 1, 2, 3, 4, 5 or 6. For example, (Ar ² ) _m ' can be selected from:

wherein R ⁴ , at each occurrence, independently is H or R ³ ; and R ⁵ , at each occurrence, independently is H, oxo, =C(CN) ₂ , or R ³ , wherein R ³ is as defined herein. For example, R ³ can be selected from a halogen, CN, oxo, =C(CN) ₂ , a C _{1 -} o alkyl group, a C _{1 -4} o haloalkyl group, a Ci-40 alkoxy group, and a C _{1 -4} o alkylthio group. In particular embodiments,

wherein R ^c is selected from H, a C e alkyl group, a Ce-u aryl group, and a -C e alkyl-C6-i4 ar l group.

[0075] To illustrate, the repeat unit M ¹ can be selected from:

[0076] In certain embodiments, the present oligomeric or polymeric compounds can include only the repeat unit M ¹ . Accordingly, certain embodiments of the present oligomeric or polymeric compounds can be selected from formulae (1)-(10):

(7) (8)

(9) (10)

wherein R ³ , W, and n are as defined herein. For example, R ³ can be a C3-20 alkyl group, and n can be an integer in the range from 3 to 10,000.

[0077] In certain embodiments, the present oligomeric or polymeric compounds can include the repeat unit M ¹ and a second repeat unit M ² , wherein M ² is an optionally substituted polycyclic (8 to 14-membered) (hetero)aryl groups. For example, M ² can be selected from:

group, -(CH ₂ CH ₂ 0) _t -R ^e , -(CF ₂ CF ₂ 0) _t R ^e , -(CH ₂ CF ₂ 0) _t R ^e , or -(CF ₂ CH ₂ 0) _t R ^e ; and R ⁷ , at each occurrence, independently is H, halogen, CN, a C _1-4 o alkyl group, a C _1-4 o alkoxy group, a Ci-40 alkylthio group, a C _1- o haloalkyl group, a C ₆ -u aryl group optionally substituted with 1- 2 Ci-40 alkyl groups, C _1-4 o alkoxy groups, C _1-4 o alkylthio groups, or C _1-4 o haloalkyl groups, a 5-14 heteroaryl group optionally substituted with 1-2 C _1- o alkyl groups, C _1-4 o alkoxy groups, Ci-40 alkylthio groups, or Ci _-40 haloalkyl groups, -(OCH ₂ CH ₂ ) _t OR ^e , -(OCF ₂ CF ₂ ) _t OR ^e , -(OCH ₂ CF ₂ ) _t OR ^e , -(OCF ₂ CH ₂ ) _t OR ^e , -(CH ₂ CH ₂ 0) _t -R ^e , -(CF ₂ CF ₂ 0) _t R ^e , -(CH ₂ CF ₂ 0) _t R ^e , or - (CF ₂ CH ₂ 0) _t R ^e ; wherein t is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; and R ^e is a Ci _-20 alkyl group or a C _1-2 o haloalkyl group.

[0078] In certain embodiments, M ² can be an optionally substituted biheteroaryl group. In embodiments where each of the heteroaryl groups in the biheteroaryl group is mono- substituted, the substitution groups can orient themselves in a head-to-head (H-H), head-to- tail (H-T), or tail-to-tail (T-T) manner. In particular embodiments, the biheteroaryl group can comprise two mono-substituted heteroaryl groups that are head-to-head (H-H) in orientation to each other. For example, the head-to-head substituted biheteroaryl group can have the formula:

wherein:

L", at each occurrence, independently is selected from -CH ₂ -, -0-, -S-, and -Se-;

R, at each occurrence, independently is selected from a C _1- o alkyl group, a C ₂ -40 alkenyl group, a C ₂ -40 alkynyl group, and a C _1-4 o haloalkyl group, wherein one or more non-adjacent CH ₂ groups independently are optionally replaced by -0-, -S-, or -Se-;

X ¹ and X ² , at each occurrence, are independently selected from S, O, and Se; and

X ³ and X ⁴ , at each occurrence, are independently selected from N, CH and CF.

[0079] Examples of such embodiments can include:

[0080] The repeat units M ¹ and M ² can be repeated in a regular (e.g., alternating) or random manner. If either unit includes substituted moieties, the copolymers can be regioregular or regiorandom in terms of the orientation of the various units relative to each other.

[0081] In particular embodiments, M ¹ and M ² can be repeated in an altemating manner. Illustrative examples of these embodiments can include:

(12)









41

42

where R ¹ is a C _6- 4o alkyl group; R ³ is a C _6- 4o alkyl group; R ⁴ is selected from H, F, CI, CN, a Ci-40 alkyl group, a C _1-4 o haloalkyl group, a C _1-4 o alkoxy group, and a C _1-4 o alkylthio group; R ⁷ is selected from a C _1- o alkyl group, a C _1-4 o alkoxy group, a C _1-4 o alkylthio group, a C _1-4 o haloalkyl group, a C6-i ₄ aryl group optionally substituted with 1-2 C _1- o alkyl groups, C _1-4 o alkoxy groups, C _1-4 o alkylthio groups, or C _1-4 o haloalkyl groups, and a 5-14 heteroaryl group optionally substituted with 1-2 C _1-4 o alkyl groups, C _1-4 o alkoxy groups, C _1-4 o alkylthio groups, or Ci-40 haloalkyl groups; and W and n are as defined herein.

[0082] In certain embodiments, the present oligomeric or polymeric compounds can include two M^M ² groups, i.e., a first repeat unit comprising M ¹ and M ² and a second repeat unit comprising M ¹ and M ² , where M ¹ and M ² include the same moieties as M ¹ and M ² , except that at least one pair of those moieties are differently substituted. The repeat unit comprising M ¹ and M ² and the repeat unit comprising M ¹ and M ² together can form a random polymer, where the molar ratio of the repeat unit comprising M ¹ and M ² and the repeat unit comprising M ¹ and M ² can be the same or different.

[0083] To illustrate, examples of such random polymers can include a combination of (14) and (15), a combination of (17) and (18), a combination of (20) and (21), a combination of (23) and (24), a combination of (26) and (27), a combination of (29) and (30), a combination of (32) and (33), a combination of (35) and (36), a combination of (38) and (39), a combination of (41) and (42), and a combination of (44) and (45).

[0084] Compounds of the present teachings can be prepared according to procedures analogous to those described in the Examples. In particular, Stille coupling can be used to prepare polymeric and co-polymeric compounds according to the present teachings with high molecular weight and purity, as confirmed by 1H NMR spectra, elemental analysis, and GPC measurements. [0085] Alternatively, the present compounds can be prepared from commercially available starting materials, compounds known in the literature, or via other readily prepared intermediates, by employing standard synthetic methods and procedures known to those skilled in the art. Standard synthetic methods and procedures for the preparation of organic molecules and functional group transformations and manipulations can be readily obtained from the relevant scientific literature or from standard textbooks in the field. It will be appreciated that where typical or preferred process conditions (i.e., reaction temperatures, times, mole ratios of reactants, solvents, pressures, etc.) are given, other process conditions can also be used unless otherwise stated. Optimum reaction conditions can vary with the particular reactants or solvent used, but such conditions can be determined by one skilled in the art by routine optimization procedures. Those skilled in the art of organic synthesis will recognize that the nature and order of the synthetic steps presented can be varied for the purpose of optimizing the formation of the compounds described herein.

[0086] The processes described herein can be monitored according to any suitable method known in the art. For example, product formation can be monitored by spectroscopic means, such as nuclear magnetic resonance spectroscopy (NMR, e.g., Η or ¹³ C), infrared spectroscopy (IR), spectrophotometry (e.g., UV-visible), mass spectrometry (MS), or by chromatography such as high pressure liquid chromatograpy (HPLC), gas chromatography (GC), gel-permeation chromatography (GPC), or thin layer chromatography (TLC).

[0087] The reactions or the processes described herein can be optionally carried out in suitable solvents which can be readily selected by one skilled in the art of organic synthesis. Suitable solvents typically are substantially nonreactive with the reactants, intermediates, and/or products at the temperatures at which the reactions are carried out, i.e., temperatures that can range from the solvent's freezing temperature to the solvent's boiling temperature. A given reaction can be carried out in one solvent or a mixture of more than one solvent. Depending on the particular reaction step, suitable solvents for a particular reaction step can be selected.

[0088] Certain embodiments disclosed herein can be stable under ambient conditions ("ambient stable"), soluble in common solvents, and in turn solution-processable into various articles, structures, or devices. As used herein, a compound can be considered "ambient stable" or "stable at ambient conditions" when the carrier mobility or the reduction-potential of the compound 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 polymer according to the present teachings can be described as ambient stable if its carrier mobility or reduction potential 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. Without wishing to be bound by any particular theory, it is believed that the strong electron-depleted electronic structure of the thienocoronene moiety, and in the case of the polymers, the regioregular highly π-conjugated polymeric backbone, can make the present compounds ambient-stable n- channel semiconductor materials without requiring additional π-core functionalization (i.e., core substitution of the thienocoronene moiety) with strong electron-withdrawing functionalities.

[0089] As used herein, a compound can be considered soluble in a solvent when at least 0.1 mg of the compound can be dissolved in 1 mL of the solvent. Examples of common organic solvents include petroleum ethers; acetonitrile; aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; ketones such as acetone, and methyl ethyl ketone; ethers such as tetrahydrofuran, dioxane, bis(2-methoxyethyl) ether, diethyl ether, di-isopropyl ether, and t-butyl methyl ether; alcohols such as methanol, ethanol, butanol, and isopropyl alcohol; aliphatic hydrocarbons such as hexanes; esters such as methyl acetate, ethyl acetate, methyl formate, ethyl formate, isopropyl acetate, and butyl acetate; amides such as

dimethylformamide and dimethylacetamide; sulfoxides such as dimethylsulfoxide;

halogenated aliphatic and aromatic hydrocarbons such as dichloromethane, chloroform, ethylene chloride, chlorobenzene, dichlorobenzene, and trichlorobenzene; and cyclic solvents such as cyclopentanone, cyclohexanone, and 2-methypyrrolidone.

[0090] As used herein, "solution-processable" refers to compounds (e.g., thienocoronene- imide copolymers), materials, or compositions that can be used in various solution-phase processes including spin-coating, printing (e.g., inkjet printing, screen printing, pad printing, offset printing, gravure printing, flexographic printing, lithographic printing, mass-printing and the like), spray coating, electrospray coating, drop casting, slot coating, dip coating, and blade coating.

[0091] Compounds of the present teachings can be used to prepare semiconductor materials (e.g., compositions and composites), which in turn can be used to fabricate various articles of manufacture, structures, and devices. In some embodiments, semiconductor materials incorporating one or more compounds of the present teachings can exhibit p-type semiconductor activity, ambipolar activity, light absorption, and/or light emission.

[0092] The present teachings, therefore, further provide methods of preparing a semiconductor material. The methods can include preparing a composition that includes one or more compounds disclosed herein dissolved or dispersed in a liquid medium such as a solvent or a mixture of solvents, depositing the composition on a substrate to provide a semiconductor material precursor, and processing (e.g., heating) the semiconductor precursor to provide a semiconductor material (e.g., a thin film semiconductor) that includes a compound disclosed herein. In various embodiments, the liquid medium can be an organic solvent, an inorganic solvent such as water, or combinations thereof. In some embodiments, the composition can further include one or more additives independently selected from viscosity modulators, detergents, dispersants, binding agents, compatiblizing agents, curing agents, initiators, humectants, antifoaming agents, wetting agents, pH modifiers, biocides, and bactereriostats. For example, surfactants and/or polymers (e.g., polystyrene, polyethylene, poly-alpha-methylstyrene, polyisobutene, polypropylene,

polymethylmethacrylate, and the like) can be included as a dispersant, a binding agent, a compatiblizing agent, and/or an antifoaming agent. In some embodiments, the depositing step can be carried out by printing, including inkjet printing and various contact printing techniques (e.g., screen-printing, gravure printing, offset printing, pad printing, lithographic printing, flexographic printing, and microcontact printing). In other embodiments, the depositing step can be carried out by spin coating, drop-casting, zone casting, dip coating, blade coating, or spraying.

[0093] Various articles of manufacture including electronic devices, optical devices, and optoelectronic devices, such as thin film semiconductors, field effect transistors (e.g., thin film transistors), photovoltaics, photodetectors, organic light emitting devices such as organic light emitting diodes (OLEDs) and organic light emitting transistors (OLETs),

complementary metal oxide semiconductors (CMOSs), complementary inverters, diodes, capacitors, sensors, D flip-flops, rectifiers, and ring oscillators, that make use of the compounds disclosed herein are within the scope of the present teachings as are methods of making the same. The present compounds can offer processing and operation advantages in the fabrication and/or the use of these devices. [0094] For example, articles of manufacture such as the various devices described herein can be an electronic or optoelectronic device including a first electrode, a second electrode, and a semiconducting component in contact with the first electrode and the electrode, where the semiconducting component includes a compound of the present teachings. These devices can include a composite having a semiconducting component (or semiconductor material) of the present teachings and a substrate component and/or a dielectric component. The substrate component can be selected from doped silicon, an indium tin oxide (ITO), ITO-coated glass, ITO-coated polyimide or other plastics, aluminum or other metals alone or coated on a polymer or other substrate, a doped polythiophene, and the like. The dielectric component can be prepared from inorganic dielectric materials such as various oxides (e.g., Si0 ₂ , AI2O ₃ , Hf0 ₂ ), organic dielectric materials such as various polymeric materials (e.g., polycarbonate, polyester, polystyrene, polyhaloethylene, polyacrylate), and self-assembled superlattice/self- assembled nanodielectric (SAS/SAND) materials (e.g., as described in Yoon, M-H. et al, PNAS, 102 (13): 4678-4682 (2005), the entire disclosure of which is incorporated by reference herein), as well as hybrid organic/inorganic dielectric materials (e.g., described in U.S. Patent Application Serial No. 11/642,504, the entire disclosure of which is incorporated by reference herein). In some embodiments, the dielectric component can include the crosslinked polymer blends described in U.S. Patent Application Serial Nos. 11/315,076, 60/816,952, and 60/861,308, the entire disclosure of each of which is incorporated by reference herein. The composite also can include one or more electrical contacts. Suitable materials for the source, drain, and gate electrodes include metals (e.g., Au, Al, Ni, Cu), transparent conducting oxides (e.g., ITO, IZO, ZITO, GZO, GIO, GITO), and conducting polymers (e.g., poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), polyaniline (PANI), polypyrrole (PPy)). One or more of the composites described herein can be embodied within various organic electronic, optical, and optoelectronic devices such as organic thin film transistors (OTFTs), specifically, organic field effect transistors (OFETs), as well as sensors, capacitors, unipolar circuits, complementary circuits (e.g., inverter circuits), and the like.

[0095] Accordingly, an aspect of the present teachings relates to methods of fabricating an organic field effect transistor that incorporates a semiconductor material of the present teachings. The semiconductor materials of the present teachings can be used to fabricate various types of organic field effect transistors including top-gate top-contact capacitor structures, top-gate bottom-contact capacitor structures, bottom-gate top-contact capacitor structures, and bottom-gate bottom-contact capacitor structures.

[0096] In Figure 1, there is schematically illustrated a bottom-gate, top-contact OTFT configuration comprised of a substrate, in contact therewith a gate electrode and a layer of a gate dielectric. On top of the gate dielectric there is an organic semiconductor layer. Two conductive contacts, source electrode and drain electrode, are deposited on top of the organic semiconductor layer.

[0097] Figure 2 schematically illustrates a bottom-gate, bottom-contact OTFT

configuration comprised of a substrate, a gate electrode, a source electrode and a drain electrode, a gate dielectric layer, and an organic semiconductor layer.

[0098] Figure 3 schematically illustrates a top-gate, bottom-contact OTFT configuration comprised of a substrate, a gate electrode, a source electrode and a drain electrode, a gate dielectric layer, and an organic semiconductor layer.

[0099] Figure 4 schematically illustrates a top-gate, top-contact OTFT configuration comprised of a substrate, a gate electrode, a source electrode and a drain electrode, a gate dielectric layer, and an organic semiconductor layer.

[0100] The semiconductor layer can have a thickness ranging, for example, from about 10 nanometers to about 1 micrometer with a preferred thickness of from about 20 to about 200 nanometers. The OTFT devices contain a semiconductor channel with a width, Wand length, L. The semiconductor channel width may be, for example, from about 1 micrometer to about 5 millimeters, with a specific channel width being about 5 micrometers to about 1 millimeter. The semiconductor channel length may be, for example, from about 10 nanometers to about 1 millimeter with a more specific channel length being from about 20 nanometers to about 500 micrometers.

[0101] In certain embodiments, OTFT devices can be fabricated with the present compounds on doped silicon substrates, using Si0 ₂ as the dielectric, in top-contact geometries. In particular embodiments, the active semiconductor layer which incorporates at least a compound of the present teachings can be deposited at room temperature or at an elevated temperature. In other embodiments, the active semiconductor layer which incorporates at least one compound of the present teachings can be applied by spin-coating or printing as described herein. For top-contact devices, metallic contacts can be patterned on top of the films using shadow masks. [0102] In certain embodiments, OTFT devices can be fabricated with the present compounds on plastic foils, using polymers as the dielectric, in top-gate bottom-contact geometries. In particular embodiments, the active semiconducting layer which incorporates at least a compound of the present teachings can be deposited at room temperature or at an elevated temperature. In other embodiments, the active semiconducting layer which incorporates at least a compound of the present teachings can be applied by spin-coating or printing as described herein. Gate and source/drain contacts can be made of Au, other metals, or conducting polymers and deposited by vapor-deposition and/or printing.

[0103] In various embodiments, a semiconducting component incorporating compounds of the present teachings can exhibit semiconducting activity, for example, a carrier mobility of 10 ^"4 cm ² /V -sec or greater and/or a current on/off ratio (WW) of 10 ³ or greater.

[0104] Other articles of manufacture in which compounds of the present teachings are useful are photovoltaics or solar cells. Compounds of the present teachings can exhibit broad optical absorption and/or a tuned redox properties and bulk carrier mobilities, making them desirable for such applications. Accordingly, the compounds described herein can be used as a donor (p-type) semiconductor material in a photovoltaic design, which includes an adjacent n-type semiconductor material that forms a p-n junction. The compounds can be in the form of a thin film semiconductor, which can be deposited on a substrate to form a composite. Exploitation of compounds of the present teachings in such devices is within the knowledge of a skilled artisan.

[0105] In various embodiments, a semiconducting component incorporating compounds of the present teachings can enable photovoltaic cells with power conversion efficiency of about 1% or greater.

[0106] Accordingly, another aspect of the present teachings relates to methods of fabricating an organic light-emitting transistor, an organic light-emitting diode (OLED), or an organic photovoltaic device that incorporates one or more semiconductor materials of the present teachings. Figure 5 illustrates a representative structure of a bulk-heteroj unction organic photovoltaic device (also known as solar cell) which can incorporate one or more compounds of the present teachings as the donor and/or acceptor materials. As shown, a representative solar cell 20 generally includes a transparent substrate 28 (e.g., glass), an anode 22 (e.g., ITO), a cathode 26 (e.g., aluminium or calcium), and a photoactive layer 24 between the anode and the cathode which can incorporate one or more compounds of the present teachings as the electron donor (p-channel) and/or electron acceptor (n-channel) materials. Figure 6 illustrates a representative structure of an OLED which can incorporate one or more compounds of the present teachings as electron-transporting and/or emissive and/or hole-transporting materials. As shown, an OLED generally includes a substrate 30 (not shown), a transparent anode 32 (e.g., ITO), a cathode 40 (e.g., metal), and one or more organic layers which can incorporate one or more compounds of the present teachings as hole-transporting (n-channel) (layer 34 as shown) and/or emissive (layer 36 as shown) and/or electron-transporting (p-channel) materials (layer 38 as shown). In embodiments where the present compounds only have one or two of the properties of hole transport, electron transport, and emission, the present compounds can be blended with one or more further organic compounds having the remaining required property or properties.

[0107] The following examples are provided to illustrate further and to facilitate the understanding of the present teachings and are not in any way intended to limit the invention.

[0108] Example 1 : Synthesis of polymers PI and P2 comprising 3.7-diphenyl- dipyrrolo[2.3-b:2'.3'-elpyrazine-2.6(lH.5H)-dione.

[0109] The following example describes the preparation of certain compounds of the present teachings and related intermediates.

[0110] All reagents were purchased from commercial sources and used without further purification unless otherwise noted.

Scheme 1

PI P2

[0111] Scheme 1 above illustrates a representative synthetic route to building block 3, which synthetic route is analogous to the procedures described in German Patent Publication No. DE 3918178 for preparing certain small molecules relating to building block 3. As shown in Scheme 1, building block 3 can be copolymerized with various M ² groups using coupling chemistries known to those skilled in the art to provide copolymers such as PI and P2. Analogs of building block 3 also can be made by replacing ethyl 2-(4-bromophenyl)-2- oxoacetate with, for example, ethyl 2-(4-bromothienyl)-2-oxoacetate.

[0112] Synthesis of compound 1.

[0113] Under argon protection, a mixture of l,4-diacetylpiperazine-2,5-dione (1.29 g, 6.5 mmol), ethyl 2-(4-bromophenyl)-2-oxoacetate (3.86 g, 15 mmol) and triethylamine (2.53 g) were heated at 55-60°C for 8.5 hr under stirring. A red residue was formed after 2 hr. After removing most of triethylamine under vacuum, a red oily solid was obtained, which was triturated and stirred in 10 mL of methanol for 12 hr at room temperature. The mixture was cooled down to 0°C and stirred for an additional 1.5 hr. The mixture was filtered and washed with cold methanol to give an orange solid (3.2 g, 72.7 %). ¾ NMR spectrum of compound 1 is shown in Figure 7.

[0114] Synthesis of compound 2.

[0115] Compound 2 (2.1 g, 3.55 mmol) was heated in formamide (10 mL) at 150°C for 4 hr. In the heating process, the color changed to red, then deep brown. After cooling, 20 mL methanol was added, and the dark brown precipitate was filtered off, which was dried in vacuo to give compound 2 as a dark brown solid (0.300 g, 17 %). ^X H NMR spectrum of compound 2 is shown in Figure 8.

[0116] Synthesis of compound 3.

[0117] To a mixture of compound 2 (0.249 g. 0.5 mmol) and anhydrous K ₂ C0 ₃ (0.207 g, 1.5 mmol) in anhydrous N, N-dimethylformamide (DMF) (9 ml) was added l-(l-(3,7- dimethyloctyloxy)-2-bromoethoxy)-3,7-dimethyloctane (0.653 g, 1.55 mmol) in small portions, and the reaction mixture was further stirred and heated at 130 °C for 8 hr. The reaction mixture was allowed to cool down to room temperature, poured into water (80 mL), and stirred for 5 min. The mixture was extracted with dichloromethane (40 mL x 3), and the combined organic phase was washed with water. Removal of the solvent afforded the crude product which was further purified using a silica-gel column (eluted with CH ₂ C1 ₂ :hexane = 2: 1) to give a deep red solid (0.300 g, 51 %). ¾ NMR spectrum of compound 3 is shown in Figure 9.

[0118] Synthesis of compound 3b.

[0119] Compound 3b was prepared similar as compound 3a using 2-decyl-l- tetradecylbromide.

[0120] Synthesis of compound 3c.

[0121] Compound 3b was prepared similar as compound 3a using 2-octyl-l- dodecylbromide.

[0122] Synthesis of polymer PI.

[0123] Compound 3a (0.2712 g, 0.23 mmol) and 5,5'-bis(trimethylstannyl)-bithiophene (0.1131 g, 0.23 mmol) were charged in a 50 mL flask. After degassing and refilling argon 3 times, toluene (16 mL) and bis(triphenylphosphine)palladium(II) di chloride (3.9 mg) were added and the reaction mixture was heated to 90°C and stirred for 48 hr. The reaction temperature was then raised to 110°C and stirred for 10 hr. Bromobenzene (0.5 mL) was added and the mixture was further stirred at 110°C for 8 hr before slowly cooling down to room temperature. The mixture was then poured into 200 mL of stirring methanol. The solid was filtered off, washed with methanol, and dried. The solid was further purified by Soxhlet extraction using acetone and hexane. Finally, the remaining solid was dissolved with chloroform. Removal of solvent gave a dark solid (263 mg, 96.6 % ). UV-vis spectrum of P 1 is shown in Figure 10.

[0124] Synthesis of polymer P2.

[0125] Compound 3 (0.1889 g, 0.16 mmol) and 2,5-bis(trimethylstannyl)thieno[3, 2- b]thiophene (0.0745 g, 0.16 mmol) were charged in a 50 mL flask. After degassing and refilling argon 3 times, toluene (16 mL) and bis(triphenylphosphine)palladium(II) dichloride (2.8 mg) were added and the reaction mixture was heated to 90°C and stirred for 48 hr. The reaction temperature was then raised to 110°C and stirred for 10 hr. Bromobenzene (0.5 mL) was added and the mixture was further stirred at 110°C for 8 hr before slowly cooling down to room temperature. The mixture was then poured into 200 mL of stirring methanol. The solid was filtered off, washed with methanol, and dried. The solid was further purified by Soxhlet extraction using acetone and hexane. Finally, the remaining solid was dissolved with chloroform. Removal of solvent gave a dark solid. UV-vis spectrum of P2 is shown in

Figure 10.

[0126] Example 2: Device fabrication with present polymers as channel materials for OTFT

[0127] OTFTs can be prepared using the present oligomeric or polymeric compounds as the channel material. Using a bottom-gate, top-contact configuration (Figure 1) as an example, the OTFT device can comprise of an n-doped silicon wafer with a thermally grown silicon oxide layer with a thickness of about 200 nanometers. The wafer functions as the gate electrode while the silicon oxide layer acts as the gate dielectric. The silicon wafer typically is cleaned with isopropanol, argon plasma, isopropanol and air dried. Then the clean substrates can be immersed in a 0.1 M solution of octyltrichlorosilane (OTS8) in toluene at about 60°C for about 30 minutes. Subsequently, the substrates can be washed with toluene, isopropanol, and air dried.

The present compound can be dissolved in dichlorobenzene at a concentration of 1 percent by weight and used to deposit the semiconductor layer. The solution can be filtrated through a 1 micrometer syringe filter, and then spin-coated onto the OTS8-treated silicon substrate at 1000 rpm for 120 seconds, resulting in a thin film with a thickness of about 20 to about 50 nanometers. After being dried in a vacuum oven at about 70°C for about 5 to 10 hours, gold source and drain electrodes of about 50 nanometers in thickness for each can be deposited on top of the semiconductor layer by vacuum deposition through a shadow mask with various channel lengths and widths, thus creating a series of transistors of various dimensions. [0128] Evaluation of field-effect thin film transistor performance can be accomplished using a Keithley Semiconductor Parameter Analyzer. The carrier mobility, μ, can be calculated from the data in the saturated regime (gate voltage, VG < source-drain voltage, VSD) according to equation (1)

I _SD = C^ (W/2L) (VG-V _T ) ² (1) where ISD is the drain current at the saturated regime, W and L were, respectively, the semiconductor channel width and length, is the capacitance per unit area of the gate dielectric layer, and VG and VT are, respectively, the gate voltage and threshold voltage. VT of the device can be determined from the relationship between the square root of ISD at the saturated regime and VG of the device by extrapolating the measured data to ISD = 0.