CONJUGATED POLYMERS

Abstract

The invention relates to novel conjugated polymers containing one or more 5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diylunits (hereinafter referred to as “FF-BTZ” units) and two or more different bridged bithiophene units, to methods for their preparation and educts or intermediates used therein, to polymer blends, mixtures and formulations containing them, to the use of the polymers, polymer blends, mixtures and formulations as organic semiconductors in, or for the preparation of, organic electronic (OE) devices, especially organic photovoltaic (OPV) devices and organic photodetectors (OPD), and to OE, OPV and OPD devices comprising, or being prepared from, these polymers, polymer blends, mixtures or formulations.

Claims

1. A polymer comprising one or more units selected from formula A and two or more distinctive units selected from formula D ##STR00070## wherein the individual radicals, independently of each other, and on each occurrence identically or differently, have the following meanings V.sup.1 C or NR.sup.1, V.sup.2 C or NR.sup.2, W S, O, CR.sup.3R.sup.4, SiR.sup.3R.sup.4, GeR.sup.3R.sup.4, NR.sup.3, R.sup.1-4 H, halogen, CN, or straight-chain, branched or cyclic alkyl with 1 to 30 C atoms, in which one or more CH.sub.2 groups are optionally replaced by —O—, —S—, —C(═O)—, —C(═S)—, —C(═O)—O—, —O—C(═O)—, —NR.sup.0—, —SiR.sup.0R.sup.00—, —CF.sub.2—, —CR.sup.0═CR.sup.00—, —CY.sup.1═CY.sup.2— or —C≡C— in such a manner that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, Cl, Br, I or CN, and in which one or more CH.sub.2 or CH.sub.3 groups are optionally replaced by a cationic or anionic group, or denote a saturated or unsaturated, non-aromatic carbo- or heterocyclic group, or an aryl, heteroaryl, aryloxy or heteroaryloxy group, wherein each of the aforementioned cyclic groups has 5 to 20 ring atoms, is mono- or polycyclic, does optionally contain fused rings, and is unsubstituted or substituted by one or more identical or different groups R.sup.S, R.sup.S halogen, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(═O)NR.sup.0R.sup.00, —C(═O)X.sup.0, —C(═O)R.sup.0, —NH.sub.2, —NR.sup.0R.sup.00, —SH, —SR.sup.0, —SO.sub.3H, —SO.sub.2R.sup.0, —OH, —NO.sub.2, —CF.sub.3, —SF.sub.5, optionally substituted silyl, or carbyl or hydrocarbyl with 1 to 40 C atoms that is optionally substituted and optionally comprises one or more hetero atoms, Y.sup.1, Y.sup.2 H, F, Cl or CN, X.sup.0 halogen, R.sup.0, R.sup.00 H or alkyl with 1 to 24 C-atoms.

2. The polymer according to claim 1, wherein the units of formula D are selected from the following subformulae ##STR00071## wherein R.sup.1-4 are as defined in claim 1.

3. The polymer according to claim 2, comprising at least one unit of formula A and at least two different units selected from different formulae D1*-D8* as defined in claim 2.

4. The polymer according to claim 2, wherein R.sup.1 and R.sup.2 in formulae D and D1*-D8* are H.

5. The polymer according to claim 2, wherein R.sup.3 and R.sup.4 in formulae D1*-D8* are different from H, and are selected from the following groups: the group consisting of straight-chain, branched or cyclic alkyl with 1 to 50, preferably 1 to 30, C atoms that is optionally fluorinated, the group consisting of straight-chain or branched alkyl, alkoxy or sulfanylalkyl with 1 to 30 C atoms, and straight-chain or branched alkylcarbonyl, alkylcarbonyloxy or alkyloxycarbonyl with 2 to 30 C atoms, each of the aforementioned groups being unsubstituted or substituted by one or more F atoms, the group consisting of aryl, heteroaryl, aryloxy and heteroaryloxy, each of which is optionally fluorinated, alkylated or alkoxylated and has 4 to 30 ring atoms, the group consisting of straight-chain, branched or cyclic alkyl with 1 to 50, preferably 2 to 30 C atoms, in which one or more CH.sub.2 or CH.sub.3 groups are replaced by a cationic or anionic group.

6. The polymer according to claim 1, additionally comprising one or more units selected from the group consisting of the following formulae ##STR00072## ##STR00073## wherein R.sup.11 and R.sup.12 independently of each other denote H or have one of the meanings of R.sup.S as defined in claim 1.

7. The polymer according to claim 1, characterized in that it is selected from the following formulae ##STR00074## ##STR00075## wherein the individual radicals, independently of each other, and on each occurrence identically or differently, have the following meanings W.sup.1-4 selected from S, O, CR.sup.3R.sup.4, SiR.sup.3R.sup.4, GeR.sup.3R.sup.4 and NR.sup.3, with at least two of W.sup.1, W.sup.2, W.sup.3 and W.sup.4 being different from each other, R.sup.1-4 the meaning given in claim 1, Sp.sup.1,2 a spacer unit selected from formulae Sp1 to Sp16, ##STR00076## ##STR00077## wherein R.sup.11 and R.sup.12 independently of each other denote H or have one of the meanings of R.sup.S as defined in claim 1, A.sup.1-3 arylene or heteroarylene having 5 to 20 ring atoms, which is mono- or polycyclic, optionally contains fused rings, and is unsubstituted or substituted by one or more identical or different groups R.sup.S as defined in claim 1, a, b, c, d, e, f >0 and ≦1, with a+b or a+b+c+d, or a+b+c+d+e+f, respectively, being 1, n an integer >1.

8. The polymer according to claim 1, characterized in that it is selected from the following formulae ##STR00078## ##STR00079## ##STR00080## ##STR00081## ##STR00082## ##STR00083## wherein R.sup.21 to R.sup.24 have independently of each other one of the meanings given for R.sup.3 in claim 1, a, b, c, d >0 and ≦1, with a+b or a+b+c+d, respectively, being 1, n an integer >1.

9. The polymer according to claim 7, which is selected of formula P
R.sup.31-chain-R.sup.32  P wherein “chain” denotes a polymer chain selected from formulae I to X as defined in claim 7, and R.sup.31 and R.sup.32 have independently of each other one of the meanings of R.sup.S, or denote, independently of each other, H, F, Br, Cl, I, —CH.sub.2Cl, —CHO, —CR′═CR″.sub.2, —SiR′R″R′″, —SiR′X′X″, —SiR′R″X′, —SnR′R″R′″, —BR′R″, —B(OR′)(OR″), —B(OH).sub.2, —O—SO.sub.2—R′, —C≡CH, —C≡C—SiR′.sub.3, —ZnX′ or an endcap group, X′ and X″ denote halogen, R′, R″ and W′ have independently of each other one of the meanings of R.sup.0, and two of R′, R″ and R′″ may also together form a cyclosilyl, cyclostannyl, cycloborane or cycloboronate group with 2 to 20 C atoms together with the respective hetero atom to which they are attached.

10. A mixture or polymer blend comprising one or more polymers according to claim 1 and one or more compounds having one or more of a semiconducting, charge transport, hole transport, electron transport, hole blocking, electron blocking, electrically conducting, photoconducting and light emitting property.

11. The mixture or polymer blend according to claim 10, characterized in that it further comprises one or more n-type organic semiconducting compounds or polymers.

12. The mixture or polymer blend according to claim 11, characterized in that the n-type organic semiconducting compounds are selected from fullerenes or substituted fullerenes.

13. A formulation comprising one or more polymers according to claim 1 and one or more organic solvents.

14. Use of a polymer according to claim 1 as semiconducting, charge transport, electrically conducting, photoconducting or light emitting material, or in an optical, electrooptical, electronic, electroluminescent or photoluminescent device, or in a component of such a device or in an assembly comprising such a device or component.

15. A semiconducting, charge transport, electrically conducting, photoconducting or light emitting material, which comprises a polymer according to claim 1.

16. An optical, electrooptical, electronic, electroluminescent or photoluminescent device, or a component thereof, or an assembly comprising it, which is prepared using a formulation according to claim 13.

17. An optical, electrooptical, electronic, electroluminescent or photoluminescent device, or a component thereof, or an assembly comprising it, which comprises a polymer.

18. The optical, electrooptical, electronic, electroluminescent or photoluminescent device of claim 17, which is selected from organic field effect transistors (OFET), organic thin film transistors (OTFT), organic light emitting diodes (OLED), organic light emitting transistors (OLET), organic photovoltaic devices (OPV), organic photodetectors (OPD), dye-sensitized solar cells (DSSC), perovskite-based solar cells, organic solar cells, laser diodes, Schottky diodes, photoconductors and photodetectors.

19. The component of an optical, electrooptical, electronic, electroluminescent or photoluminescent device of claim 18 which is selected from charge injection layers, charge transport layers, interlayers, planarising layers, antistatic films, polymer electrolyte membranes (PEM), conducting substrates and conducting patterns.

20. The assembly of an optical, electrooptical, electronic, electroluminescent or photoluminescent device of claim 17, which is selected from integrated circuits (IC), radio frequency identification (RFID) tags or security markings or security devices containing them, flat panel displays or backlights thereof, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, biosensors and biochips.

21. A bulk heterojunction which comprises a mixture or polymer blend according to claim 11.

22. A bulk heterojunction (BHJ) OPV device or inverted BHJ OPV device, comprising a bulk heterojunction of claim 21.

23. A process of preparing a polymer according to claim 1, which comprises coupling one or more monomers selected from the following formulae with each other and/or with one or more co-monomers in an aryl-aryl coupling reaction
R.sup.33-A-R.sup.34  MI
R.sup.33-D-R.sup.34  MII
R.sup.33-Sp.sup.1-R.sup.34  MIII
R.sup.33-Sp.sup.2-R.sup.34  MIV
R.sup.33-A.sup.1-R.sup.34  MV
R.sup.33-Sp.sup.2-R.sup.34  MVI wherein at least one monomer is selected of formula MI and at least one monomer is selected of formula MII, A denotes a unit of formula A as defined in claim 1, D denotes a unit of formula D as defined in claim 1, Sp.sup.1,2 denote a spacer unit ##STR00084## wherein R.sup.11 and R.sup.12 independently of each other denote H or have one of the meanings of R.sup.S as defined in claim 1, A.sup.1,2 denote an acceptor unit which is arylene or heteroarylene having 5 to 20 ring atoms, which is mono- or polycyclic, optionally contains fused rings, and is unsubstituted or substituted by one or more identical or different groups R.sup.S as defined in claim 1, and R.sup.33 and R.sup.34 are, independently of each other, selected from the group consisting of H which is preferably an activated C—H bond, Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate, —SiMe.sub.2F, —SiMeF.sub.2, —O—SO.sub.2Z.sup.1, —B(OZ.sup.2).sub.2, —CZ.sup.3═C(Z.sup.3).sub.2, —C≡CH, —C≡CSi(Z.sup.1).sub.3, —ZnX.sup.0 and —Sn(Z.sup.4).sub.3, wherein X.sup.0 is halogen, Z.sup.1-4 are selected from the group consisting of alkyl and aryl, each being optionally substituted, and two groups Z.sup.2 may also form a cycloboronate group having 2 to 20 C atoms with the B- and O-atoms.

Description

DETAILED DESCRIPTION

[0084] The polymers of the present invention are easy to synthesize and exhibit advantageous properties. They show good processability for the device manufacture process, high solubility in organic solvents, and are especially suitable for large scale production using solution processing methods. At the same time, the co-polymers derived from monomers of the present invention and electron donor monomers show low bandgaps, high charge carrier mobilities, high external quantum efficiencies in BHJ solar cells, good morphology when used in p/n-type blends e.g. with fullerenes, high oxidative stability, a long lifetime in electronic devices, and are promising materials for organic electronic OE devices, especially for OPV devices with high power conversion efficiency.

[0085] The polymers according to the present invention are especially suitable as p-type semiconductors for the preparation of blends of p-type and n-type semiconductors which are suitable for use in BHJ photovoltaic devices.

[0086] Besides, the polymers of the present invention show the following advantageous properties: [0087] i) The random nature of the polymer backbone leads to improved entropy of solution, especially in non-halogenated solvents, resulting in improved polymer solubility. [0088] ii) Variation of the bridged bithiophene units in the polymer backbone provides HOMO energy level fine tuning, thus reducing the energy loss in the electron transfer process between the polymer and the n-type material (i.e. fullerene, graphene, metal oxide) in the active layer. [0089] iii) Additional electron accepting units (A.sub.1) in the polymer backbone provides LUMO energy level fine tuning, thus reducing the energy loss in the electron transfer process between the polymer and the n-type material (i.e. fullerene, graphene, metal oxide) in the active layer. [0090] iv) The spacer (Sp.sub.1) units provide additional disorder, flexibility and freedom of rotation in the polymer backbone, leading to improved entropy of solution, especially in non-halogenated solvents, while maintaining sufficient structural order in the polymer backbone, resulting in improved polymer solubility. [0091] v) The spacer (Sp.sub.1) units, which can each possess more than one solubilising group, enable higher polymer solubility in non-halogenated solvents due this increased number of solubilising groups per repeat unit.

[0092] In a preferred embodiment of the present invention the units of formula D are selected from the following subformulae

##STR00005##

wherein R.sup.1-4 are as defined above and below.

[0093] Preferred are units of formulae D1*, D2*, D3* and D4*, very preferred those of formulae D1*, D2* and D3*.

[0094] Preferably the polymer comprises at least one unit of formula A and at least two different units selected from different formulae D1*-D8*.

[0095] Preferably R.sup.1 and R.sup.2 in formulae D and D1*-D8* are H.

[0096] Preferably R.sup.3 and R.sup.4 in formulae D and D1*-D8* are different from H.

[0097] Preferably R.sup.1-4 in formulae D and D1*-D8*, when being different from H, are selected from the following groups: [0098] the group consisting of straight-chain, branched or cyclic alkyl with 1 to 50, preferably 1 to 30, C atoms that is optionally fluorinated, [0099] the group consisting of straight-chain or branched alkyl, alkoxy or sulfanylalkyl with 1 to 30 C atoms, and straight-chain or branched alkylcarbonyl, alkylcarbonyloxy or alkyloxycarbonyl with 2 to 30 C atoms, each of the aforementioned groups being unsubstituted or substituted by one or more F atoms, [0100] the group consisting of aryl, heteroaryl, aryloxy and heteroaryloxy, each of which is optionally fluorinated, alkylated or alkoxylated and has 4 to 30 ring atoms, [0101] the group consisting of straight-chain, branched or cyclic alkyl with 1 to 50, preferably 2 to 30 C atoms, in which one or more CH.sub.2 or CH.sub.3 groups are replaced by a cationic or anionic group.

[0102] If one or more of R.sup.1 to R.sup.4 denote an aryl(oxy) or heteroaryl(oxy) group, it is preferably selected from phenyl, pyrrole, furan, pyridine, thiazole, thiophene, thieno[3,2-b]thiophene or thieno[2,3-b]thiophene, each of which is optionally fluorinated, alkylated or alkoxylated.

[0103] The cationic group is preferably selected from the group consisting of phosphonium, sulfonium, ammonium, uronium, thiouronium, guanidinium or heterocyclic cations such as imidazolium, pyridinium, pyrrolidinium, triazolium, morpholinium or piperidinium cation.

[0104] Preferred cationic groups are selected from the group consisting of tetraalkylammonium, tetraalkylphosphonium, N-alkylpyridinium, N,N-dialkylpyrrolidinium, 1,3-dialkylimidazolium, wherein “alkyl” preferably denotes a straight-chain or branched alkyl group with 1 to 12 C atoms.

[0105] Further preferred cationic groups are selected from the group consisting of the following formulae

##STR00006## ##STR00007## ##STR00008##

wherein R.sup.1′, R.sup.2′, R.sup.3′ and R.sup.4′ denote, independently of each other, H, a straight-chain or branched alkyl group with 1 to 12 C atoms or non-aromatic carbo- or heterocyclic group or an aryl or heteroaryl group, each of the aforementioned groups having 3 to 20, preferably 5 to 15, ring atoms, being mono- or polycyclic, and optionally being substituted by one or more identical or different substituents R.sup.S as defined below, or denote a link to the respective group R.sup.1-4.

[0106] In the above cationic groups of the above-mentioned formulae any one of the groups R.sup.1′, R.sup.2′, R.sup.3′ and R.sup.4′ (if they replace a CH.sub.3 group) can denote a link to the group R.sup.1, or two neighbored groups R.sup.1′, R.sup.2′, R.sup.3′ or R.sup.4′ (if they replace a CH.sub.2 group) can denote a link to the respective group R.sup.1-4.

[0107] The anionic group is preferably selected from the group consisting of borate, imide, phosphate, sulfonate, sulfate, succinate, naphthenate or carboxylate, very preferably from phosphate, sulfonate or carboxylate.

[0108] In a preferred embodiment the polymer comprises, in addition to the units of formula A and the units selected from formulae D and D1*-D8*, one or more spacer units Sp selected from the group consisting of the following formulae

##STR00009## ##STR00010##

wherein R.sup.11 and R.sup.12 independently of each other denote H or have one of the meanings of R.sup.S as defined above and below.

[0109] Preferred spacer units are selected from formula Sp1, Sp4, Sp6, wherein preferably one of R.sup.11 and R.sup.12 is H or both R.sup.11 and R.sup.12 are H.

[0110] In another preferred embodiment the polymer comprises, in addition to the units of formula A and the units selected from formulae D and D1*-D8*, one or more arylene or heteroarylene units, preferably having electron donor properties, selected from the group consisting of the following formulae

##STR00011## ##STR00012## ##STR00013## ##STR00014## ##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028## ##STR00029##

wherein R.sup.11, R.sup.12, R.sup.13, R.sup.14, R.sup.15, R.sup.16, R.sup.17 and R.sup.18 independently of each other denote H or have one of the meanings of R.sup.S as defined above and below.

[0111] Preferred additional donor units are selected from formulae D1, D10, D19, D22, D25, D35, D36, D37, D38, D44, D84, D93, D94, D103, D108, D111, D137, D139, D140 or D141 wherein preferably at least one of R.sup.11, R.sup.12, R.sup.13 and R.sup.14 is different from H.

[0112] In another preferred embodiment the polymer comprises, in addition to the units of formula A and the units selected from formulae D and D1*-D8*, one or more arylene or heteroarylene units, preferably having electron acceptor properties, selected from the group consisting of the following formulae

##STR00030## ##STR00031## ##STR00032## ##STR00033## ##STR00034## ##STR00035## ##STR00036## ##STR00037## ##STR00038## ##STR00039## ##STR00040## ##STR00041## ##STR00042## ##STR00043## ##STR00044##

wherein R.sup.11, R.sup.12, R.sup.13, R.sup.14, R.sup.15 and R.sup.16 independently of each other denote H or have one of the meanings of R.sup.S as defined above and below.

[0113] Preferred additional acceptor units are selected from formulae A1, A2, A3, A20, A41, A48, A74, A85 or A94 wherein preferably at least one of R.sup.11, R.sup.12, R.sup.13 and R.sup.14 is different from H.

[0114] Further preferred additional acceptor units are selected from formula A1 wherein R.sup.11 and R.sup.12 are H.

[0115] Preferred polymers are selected from the following formulae

##STR00045## ##STR00046## ##STR00047##

wherein the individual radicals, independently of each other, and on each occurrence identically or differently, have the following meanings [0116] W.sup.1-4 selected from S, O, CR.sup.3R.sup.4, SiR.sup.3R.sup.4, GeR.sup.3R.sup.4 and NR.sup.3, preferably from CR.sup.3R.sup.4, SiR.sup.3R.sup.4 and NR.sup.3, with at least two of W.sup.1, W.sup.2, W.sup.3 and W.sup.4 being different from each other, [0117] R.sup.1-4 the meaning given in formulae D and D1*-D8* or one of the preferred meanings given above and below, [0118] Sp.sup.1, Sp.sup.2 a spacer unit selected from formulae Sp1 to Sp16, [0119] A.sup.1-3 arylene or heteroarylene having 5 to 20 ring atoms, which is mono- or polycyclic, optionally contains fused rings, and is unsubstituted or substituted by one or more identical or different groups R.sup.S as define above, preferably having electron acceptor properties, and preferably being selected from formulae A1-A94, very preferably from A1, A2, A3, A20, A41, A48, A74, A85 and A94, [0120] a, b, c, d, e, f >0 and ≦1, with a+b or a+b+c+d, or a+b+c+d+e+f, respectively, being 1, [0121] n an integer >1.

[0122] Very preferred are polymers selected from formulae I-V.

[0123] Especially preferred are polymers selected from the following subformulae

##STR00048## ##STR00049## ##STR00050## ##STR00051## ##STR00052## ##STR00053##

wherein R.sup.21 to R.sup.24 have independently of each other one of the meanings given for R.sup.3, and a, b, c, d and n are as defined above.

[0124] In the polymers of formulae I to X and their subformulae, each of a, b, c, d, e and f is preferably from 0.1 to 0.9.

[0125] In the polymers of formulae I to X and their subformulae, each of a, b, c, d, e and f has substantially the same value.

[0126] In the polymers according to the present invention, the total number of repeating units n is preferably from 2 to 10,000. The total number of repeating units n is preferably ≧5, very preferably ≧10, most preferably ≧50, and preferably ≦500, very preferably ≦1,000, most preferably ≦2,000, including any combination of the aforementioned lower and upper limits of n.

[0127] The polymers of the present invention are preferably statistical or random copolymers.

[0128] Further preferred is conjugated polymer according to the present invention selected of formula P

R.sup.31-chain-R.sup.32  P

wherein “chain” denotes a polymer chain selected of formulae I-X or their subformulae, and R.sup.31 and R.sup.32 have independently of each other one of the meanings of R.sup.S as defined above, or denote, independently of each other, H, F, Br, Cl, I, —CH.sub.2Cl, —CHO, —CR′═CR″.sub.2, —SiR′R″R′″, —SiR′X′X″, —SiR′R″X′, —SnR′R″R′″, —BR′R″, —B(OR′)(OR″), —B(OH).sub.2, —O—SO.sub.2—R′, —C≡CH, —C≡C—SiR′.sub.3, —ZnX′ or an endcap group, X′ and X″ denote halogen, R′, R″ and R′″ have independently of each other one of the meanings of R.sup.0 given in formula D, and preferably denote alkyl with 1 to 12 C atoms, and two of R′, R″ and R′″ may also form a cyclosilyl, cyclostannyl, cycloborane or cycloboronate group with 2 to 20 C atoms together with the respective hetero atom to which they are attached.

[0129] Preferred endcap groups R.sup.31 and R.sup.32 are H, C.sub.1-20 alkyl, or optionally substituted C.sub.6-12 aryl or C.sub.2-10 heteroaryl, very preferably H or phenyl.

[0130] The conjugated polymer can be prepared for example by copolymerising one or more monomers selected from the following formulae in an aryl-aryl coupling reaction

R.sup.33-A-R.sup.34  MI

R.sup.33-D-R.sup.34  MII

R.sup.33-Sp.sup.1-R.sup.34  MIII

R.sup.33-Sp.sup.2-R.sup.34  MIV

R.sup.33-A.sup.1-R.sup.34  MV

R.sup.33-Sp.sup.2-R.sup.34  MVI

wherein at least one monomer is selected of formula MI and at least two monomers are is selected of formula MII,
A denotes a unit of formula A,
D denotes a unit of formula D or D1*-D8*,
Sp.sup.1,2 denote a spacer unit as defined in formulae I-X,
A.sup.1,2 denote an acceptor unit as defined in formulae I-X,
R.sup.33 and R.sup.34 are, independently of each other, selected from the group consisting of H which is preferably an activated C—H bond, Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate, —SiMe.sub.2F, —SiMeF.sub.2, —O—SO.sub.2Z.sup.1, —B(OZ.sup.2).sub.2, —CZ.sup.3═C(Z.sup.3).sub.2, —C≡CH, —C≡CSi(Z.sup.1).sub.3, —ZnX.sup.0 and —Sn(Z.sup.4).sub.3, wherein X.sup.0 is halogen, preferably Cl, Br or I, Z.sup.1-4 are selected from the group consisting of alkyl, preferably C.sub.1-10 alkyl and aryl, preferably C.sub.6-12 aryl, each being optionally substituted, and two groups Z.sup.2 may also form a cycloboronate group having 2 to 20 C atoms with the B- and O-atoms.

[0131] The monomers of formula MI-MVI can be co-polymerised with each other and/or with other suitable co-monomers.

[0132] The polymer according to the present invention can be synthesized according to or in analogy to methods that are known to the skilled person and are described in the literature. Other methods of preparation can be taken from the examples.

[0133] For example, the polymers can be suitably prepared by aryl-aryl coupling reactions, such as Yamamoto coupling, C—H activation coupling, Suzuki coupling, Stille coupling, Sonogashira coupling, Heck coupling or Buchwald coupling. Suzuki coupling, Stille coupling and Yamamoto coupling are especially preferred. The monomers which are polymerised to form the repeat units of the polymers can be prepared according to methods which are known to the person skilled in the art.

[0134] Preferably the polymer is prepared from monomers selected from formulae MI-MVI as described above.

[0135] Another aspect of the invention is a process for preparing a polymer by coupling one or more identical or different monomers selected from formula MI-MVI with each other and/or with one or more co-monomers in a polymerisation reaction, preferably in an aryl-aryl coupling reaction.

[0136] Preferred aryl-aryl coupling and polymerisation methods used in the processes described above and below are Yamamoto coupling, Kumada coupling, Negishi coupling, Suzuki coupling, Stille coupling, Sonogashira coupling, Heck coupling, C—H activation coupling, Ullmann coupling or Buchwald coupling. Especially preferred are Suzuki coupling, Negishi coupling, Stille coupling and Yamamoto coupling. Suzuki coupling is described for example in WO 00/53656 A1. Negishi coupling is described for example in J. Chem. Soc., Chem. Commun., 1977, 683-684. Yamamoto coupling is described in for example in T. Yamamoto et al., Prog. Polym. Sci., 1993, 17, 1153-1205, or WO 2004/022626 A1. Stille coupling is described for example in Z. Bao et al., J. Am. Chem. Soc., 1995, 117, 12426-12435. C—H activation is described for example for example in M. Leclerc et al, Angew. Chem. Int. Ed. 2012, 51, 2068-2071. For example, when using Yamamoto coupling, monomers having two reactive halide groups are preferably used. When using Suzuki coupling, monomers having two reactive boronic acid or boronic acid ester groups or two reactive halide groups are preferably used. When using Stille coupling, monomers having two reactive stannane groups or two reactive halide groups are preferably used. When using Negishi coupling, monomers having two reactive organozinc groups or two reactive halide groups are preferably used. When synthesizing a linear polymer by C—H activation polymerisation, preferably a monomer as described above is used wherein at least one reactive group is an activated hydrogen bond.

[0137] Preferred catalysts, especially for Suzuki, Negishi or Stille coupling, are selected from Pd(0) complexes or Pd(II) salts. Preferred Pd(0) complexes are those bearing at least one phosphine ligand such as Pd(Ph.sub.3P).sub.4. Another preferred phosphine ligand is tris(ortho-tolyl)phosphine, i.e. Pd(o-Tol.sub.3P).sub.4. Preferred Pd(II) salts include palladium acetate, i.e. Pd(OAc).sub.2 or trans-di(μ-acetato)-bis[o-(di-o-tolylphosphino)benzyl]dipalladium(II). Alternatively the Pd(0) complex can be prepared by mixing a Pd(0) dibenzylideneacetone complex, for example tris(dibenzyl-ideneacetone)dipalladium(0), bis(dibenzylideneacetone)palladium(0), or Pd(II) salts e.g. palladium acetate, with a phosphine ligand, for example triphenylphosphine, tris(ortho-tolyl)phosphine, tris(o-methoxyphenyl)phosphine or tri(tert-butyl)phosphine. Suzuki polymerisation is performed in the presence of a base, for example sodium carbonate, potassium carbonate, cesium carbonated, lithium hydroxide, potassium phosphate or an organic base such as tetraethylammonium carbonate or tetraethylammonium hydroxide. Yamamoto polymerisation employs a Ni(0) complex, for example bis(1,5-cyclooctadienyl) nickel(0).

[0138] Suzuki, Stille or C—H activation coupling polymerisation may be used to prepare homopolymers as well as statistical, alternating and block random copolymers. Statistical, random block copolymers or block copolymers can be prepared for example from the above monomers, wherein one of the reactive groups is halogen and the other reactive group is a C—H activated bond, boronic acid, boronic acid derivative group or and alkylstannane. The synthesis of statistical, alternating and block copolymers is described in detail for example in WO 03/048225 A2 or WO 2005/014688 A2.

[0139] As alternatives to halogen as described above, leaving groups of formula —O—SO.sub.2Z.sup.1 can be used wherein Z.sup.1 is as defined above. Particular examples of such leaving groups are tosylate, mesylate and triflate.

[0140] Suitable and preferred methods for preparing a polymer according to the present invention are illustrated in the reaction Schemes below.

[0141] The generic preparation of the BTZ—F.sub.2 monomers of formula A has been described for example in WO 2011/060526 A1.

[0142] The synthesis of the bithiophene monomers of formula D has been described for example in Macromolecules, 2007, 40(26), Organometallics 2011, 30, 3233-3236, Macromolecules, 2007, 40(6) and J. Am. Chem. Soc. 2008, 130, 13167-13176.

[0143] The synthesis of random copolymers is exemplarily illustrated in Schemes 1 to 3 below, wherein A.sup.1, Sp.sup.1, W.sup.1-3, a, b, c, d and n are as defined above, and RG.sup.1 and RG.sup.2 denote a ractive group as defined for R.sup.33.

[0144] The RG.sup.1 and RG.sup.2 groups are preferably complementary to each other in a polycondensation reaction such as Suzuki coupling, Stille coupling, Sonogashira coupling, Heck coupling, Negishi coupling or C—H activation coupling. The reactive groups are preferably selected from of a first set of reactive groups consisting of Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate, and a second set of reactive groups consisting of —SiMe.sub.2F, —SiMeF.sub.2, —O—SO.sub.2Z.sup.1, —B(OZ.sup.2).sub.2, —CZ.sup.3═C(Z.sup.3).sub.2, —C≡CH, —C≡CSi(Z.sup.1).sub.3, —ZnX.sup.0 and —Sn(Z.sup.4).sub.3, wherein X and Z.sup.1-4 are as defined above.

##STR00054##

##STR00055##

##STR00056##

[0145] Preferred polymerisation conditions lead to alternating polymers which are particularly preferred for OTFT application, whereas statistical block co-polymers are prepared preferably for OPV and OPD application. Preferred polycondensation are Suzuki coupling, Stille coupling, Sonogashira coupling, Heck coupling or Buchwald coupling, Negishi coupling or C—H activation coupling where the first set of reactive groups is composed of —Cl, —Br, —I, O-tosylate, O-triflate, O-mesylate and O-nonaflate and the second set of reactive groups is composed of —H, —SiR.sub.2F, —SiRF.sub.2, —B(OR).sub.2, —CR═CHR′, —C≡CH, —ZnX, —MgX and —Sn(R).sub.3. If a Yamamoto coupling reaction is used to prepare the polymer, the reactive monomer ends are both composed independently of Cl, —Br, —I, O-tosylate, O-triflate, O-mesylate and O-nonaflate.

[0146] The novel methods of preparing a polymer as described above and below, and the novel monomers used therein, are further aspects of the invention.

[0147] The polymer according to the present invention can also be used in mixtures or polymer blends, for example together with monomeric compounds or together with other polymers having charge-transport, semiconducting, electrically conducting, photoconducting and/or light-emitting semiconducting properties, or for example with polymers having hole blocking, electron blocking properties for use as interlayers, charge blocking layers, charge transporting layer in OLED devices, OPV devices or pervorskite based solar cells. Thus, another aspect of the invention relates to a polymer blend comprising one or more polymers according to the present invention and one or more further polymers having one or more of the above-mentioned properties. These blends can be prepared by conventional methods that are described in prior art and known to the skilled person. Typically the polymers are mixed with each other or dissolved in suitable solvents and the solutions combined.

[0148] Another aspect of the invention relates to a formulation comprising one or more polymers, polymer blends or mixtures as described above and below and one or more organic solvents.

[0149] Preferred solvents are aliphatic hydrocarbons, chlorinated hydrocarbons, aromatic hydrocarbons, ketones, ethers and mixtures thereof. Additional solvents which can be used include 1,2,4-trimethylbenzene, 1,2,3,4-tetra-methyl benzene, pentylbenzene, mesitylene, cumene, cymene, cyclohexylbenzene, diethylbenzene, tetralin, decalin, 2,6-lutidine, 2-fluoro-m-xylene, 3-fluoro-o-xylene, 2-chlorobenzotrifluoride, N,N-dimethylformamide, 2-chloro-6-fluorotoluene, 2-fluoroanisole, anisole, 2,3-dimethylpyrazine, 4-fluoroanisole, 3-fluoroanisole, 3-trifluoro-methylanisole, 2-methylanisole, phenetol, 4-methylanisole, 3-methylanisole, 4-fluoro-3-methylanisole, 2-fluorobenzonitrile, 4-fluoroveratrol, 2,6-dimethylanisole, 3-fluorobenzo-nitrile, 2,5-dimethylanisole, 2,4-dimethylanisole, benzonitrile, 3,5-dimethyl-anisole, N,N-dimethylaniline, ethyl benzoate, 1-fluoro-3,5-dimethoxy-benzene, 1-methylnaphthalene, N-methylpyrrolidinone, 3-fluorobenzo-trifluoride, benzotrifluoride, dioxane, trifluoromethoxy-benzene, 4-fluorobenzotrifluoride, 3-fluoropyridine, toluene, 2-fluoro-toluene, 2-fluorobenzotrifluoride, 3-fluorotoluene, 4-isopropylbiphenyl, phenyl ether, pyridine, 4-fluorotoluene, 2,5-difluorotoluene, 1-chloro-2,4-difluorobenzene, 2-fluoropyridine, 3-chlorofluoro-benzene, 1-chloro-2,5-difluorobenzene, 4-chlorofluorobenzene, chloro-benzene, o-dichlorobenzene, 2-chlorofluorobenzene, p-xylene, m-xylene, o-xylene or mixture of o-, m-, and p-isomers. Solvents with relatively low polarity are generally preferred. For inkjet printing solvents and solvent mixtures with high boiling temperatures are preferred. For spin coating alkylated benzenes like xylene and toluene are preferred.

[0150] Examples of especially preferred solvents include, without limitation, dichloromethane, trichloromethane, tetrachloromethane, chlorobenzene, o-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, 1,8-diiodooctane, 1-chloronaphthalene, 1,8-octane-dithiol, anisole, 2,5-di-methylanisole, 2,4-dimethylanisole, toluene, o-xylene, m-xylene, p-xylene, mixture of o-, m-, and p-xylene isomers, 1,2,4-trimethylbenzene, mesitylene, cyclohexane, 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, tetraline, decaline, indane, 1-methyl-4-(1-methylethenyl)-cyclohexene (d-Limonene), 6,6-dimethyl-2-methylenebicyclo[3.1.1]heptanes (β-pinene), methyl benzoate, ethyl benzoate, nitrobenzene, benzaldehyde, tetrahydrofuran, 1,4-dioxane, 1,3-dioxane, morpholine, acetone, methylethylketone, ethyl acetate, n-butyl acetate, N,N-dimethylformamide, dimethylacetamide, dimethylsulfoxide and/or mixtures thereof.

[0151] The concentration of the polymers in the solution is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight. Optionally, the solution also comprises one or more binders to adjust the rheological properties, as described for example in WO 2005/055248 A1.

[0152] After the appropriate mixing and ageing, solutions are evaluated as one of the following categories: complete solution, borderline solution or insoluble. The contour line is drawn to outline the solubility parameter-hydrogen bonding limits dividing solubility and insolubility. ‘Complete’ solvents falling within the solubility area can be chosen from literature values such as published in “Crowley, J. D., Teague, G. S. Jr and Lowe, J. W. Jr., Journal of Paint Technology, 1966, 38 (496), 296”. Solvent blends may also be used and can be identified as described in “Solvents, W. H. Ellis, Federation of Societies for Coatings Technology, p 9-10, 1986”. Such a procedure may lead to a blend of ‘non’ solvents that will dissolve both the polymers of the present invention, although it is desirable to have at least one true solvent in a blend.

[0153] The polymer according to the present invention can also be used in patterned OSC layers in the devices as described above and below. For applications in modern microelectronics it is generally desirable to generate small structures or patterns to reduce cost (more devices/unit area), and power consumption. Patterning of thin layers comprising a polymer according to the present invention can be carried out for example by photolithography, electron beam lithography or laser patterning.

[0154] For use as thin layers in electronic or electrooptical devices the polymers, polymer blends or formulations of the present invention may be deposited by any suitable method. Liquid coating of devices is more desirable than vacuum deposition techniques. Solution deposition methods are especially preferred. The formulations of the present invention enable the use of a number of liquid coating techniques. Preferred deposition techniques include, without limitation, dip coating, spin coating, ink jet printing, nozzle printing, letter-press printing, screen printing, gravure printing, doctor blade coating, roller printing, reverse-roller printing, offset lithography printing, dry offset lithography printing, flexographic printing, web printing, spray coating, curtain coating, brush coating, slot dye coating or pad printing.

[0155] Ink jet printing is particularly preferred when high resolution layers and devices needs to be prepared. Selected formulations of the present invention may be applied to prefabricated device substrates by ink jet printing or microdispensing. Preferably industrial piezoelectric print heads such as but not limited to those supplied by Aprion, Hitachi-Koki, InkJet Technology, On Target Technology, Picojet, Spectra, Trident, Xaar may be used to apply the organic semiconductor layer to a substrate. Additionally semi-industrial heads such as those manufactured by Brother, Epson, Konica, Seiko Instruments Toshiba TEC or single nozzle microdispensers such as those produced by Microdrop and Microfab may be used.

[0156] In order to be applied by ink jet printing or microdispensing, the polymers should be first dissolved in a suitable solvent. Solvents must fulfil the requirements stated above and must not have any detrimental effect on the chosen print head. Additionally, solvents should have boiling points >100° C., preferably >140° C. and more preferably >150° C. in order to prevent operability problems caused by the solution drying out inside the print head. Apart from the solvents mentioned above, suitable solvents include substituted and non-substituted xylene derivatives, di-C.sub.1-2-alkyl formamide, substituted and non-substituted anisoles and other phenol-ether derivatives, substituted heterocycles such as substituted pyridines, pyrazines, pyrimidines, pyrrolidinones, substituted and non-substituted N,N-di-C.sub.1-2-alkylanilines and other fluorinated or chlorinated aromatics.

[0157] A preferred solvent for depositing a polymer according to the present invention by ink jet printing comprises a benzene derivative which has a benzene ring substituted by one or more substituents wherein the total number of carbon atoms among the one or more substituents is at least three. For example, the benzene derivative may be substituted with a propyl group or three methyl groups, in either case there being at least three carbon atoms in total. Such a solvent enables an ink jet fluid to be formed comprising the solvent with the compound or polymer, which reduces or prevents clogging of the jets and separation of the components during spraying. The solvent(s) may include those selected from the following list of examples: dodecylbenzene, 1-methyl-4-tert-butylbenzene, terpineol, limonene, isodurene, terpinolene, cymene, diethylbenzene. The solvent may be a solvent mixture, that is a combination of two or more solvents, each solvent preferably having a boiling point >100° C., more preferably >140° C. Such solvent(s) also enhance film formation in the layer deposited and reduce defects in the layer.

[0158] The ink jet fluid (that is mixture of solvent, binder and semiconducting compound) preferably has a viscosity at 20° C. of 1-100 mPa.Math.s, more preferably 1-50 mPa.Math.s and most preferably 1-30 mPa.Math.s.

[0159] The polymers, polymer blends, mixtures and formulations according to the present invention can additionally comprise one or more further components or additives selected for example from surface-active compounds, lubricating agents, wetting agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents which may be reactive or non-reactive, auxiliaries, colourants, dyes or pigments, sensitizers, stabilizers, nanoparticles or inhibitors.

[0160] The polymers, polymer blends and mixtures according to the present invention are useful as charge transport, semiconducting, electrically conducting, photoconducting or light emitting material in optical, electrooptical, electronic, electroluminescent or photoluminescent components or devices. In these devices, a polymer, polymer blend or mixture of the present invention is typically applied as a thin layer or film.

[0161] Thus, the present invention also provides the use of the polymer, polymer blend, mixture or layer in an electronic device. The formulation may be used as a high mobility semiconducting material in various devices and apparatus. The formulation may be used, for example, in the form of a semiconducting layer or film. Accordingly, in another aspect, the present invention provides a semiconducting layer for use in an electronic device, the layer comprising a polymer, mixture or polymer blend according to the invention. The layer or film may be less than about 30 microns. For various electronic device applications, the thickness may be less than about 1 micron thick. The layer may be deposited, for example on a part of an electronic device, by any of the aforementioned solution coating or printing techniques.

[0162] The invention additionally provides an electronic device comprising a polymer, polymer blend, mixture or organic semiconducting layer according to the present invention. Especially preferred devices are OFETs, TFTs, ICs, logic circuits, capacitors, RFID tags, OLEDs, OLETs, OPEDs, OPVs, OPDs, solar cells, laser diodes, photoconductors, photodetectors, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates and conducting patterns.

[0163] Especially preferred electronic device are OFETs, OLEDs, OPV and OPD devices, in particular bulk heterojunction (BHJ) OPV devices. In an OFET, for example, the active semiconductor channel between the drain and source may comprise the layer of the invention. As another example, in an OLED device, the charge (hole or electron) injection or transport layer may comprise the layer of the invention.

[0164] For use in OPV or OPD devices the polymer according to the present invention is preferably used in a formulation that comprises or contains, more preferably consists essentially of, very preferably exclusively of, one or more p-type (electron donor) semiconductor and one or more n-type (electron acceptor) semiconductor. The p-type semiconductor is constituted of a least one polymer according to the present invention. The n-type semiconductor can be an inorganic material such as zinc oxide (ZnO.sub.x), zinc tin oxide (ZTO), titanium oxide (TiO.sub.x), molybdenum oxide (MoO.sub.x), nickel oxide (NiO.sub.x), or cadmium selenide (CdSe), or an organic material such as graphene or a fullerene, a conjugated polymer or substituted fullerene, for example a (6,6)-phenyl-butyric acid methyl ester derivatized methano C.sub.60 fullerene, also known as “PCBM-C.sub.60” or “C.sub.60PCBM”, as disclosed for example in Science 1995, 270, 1789 and having the structure shown below, or structural analogous compounds with e.g. a C.sub.70 fullerene group or an organic polymer (see for example Coakley, K. M. and McGehee, M. D. Chem. Mater. 2004, 16, 4533).

##STR00057##

[0165] Preferably the polymer according to the present invention is blended with an n-type semiconductor such as a fullerene or substituted fullerene of formula XII to form the active layer in an OPV or OPD device wherein,

##STR00058## [0166] C.sub.n denotes a fullerene composed of n carbon atoms, optionally with one or more atoms trapped inside, [0167] Adduct.sup.1 is a primary adduct appended to the fullerene C.sub.n with any connectivity, [0168] Adduct.sup.2 is a secondary adduct, or a combination of secondary adducts, appended to the fullerene C.sub.n with any connectivity, [0169] k is an integer ≧1, [0170] and [0171] I is 0, an integer ≧1, or a non-integer >0.

[0172] In the formula XII and its subformulae, k preferably denotes 1, 2, 3 or, 4, very preferably 1 or 2.

[0173] The fullerene C.sub.n in formula XII and its subformulae may be composed of any number n of carbon atoms Preferably, in the compounds of formula XII and its subformulae the number of carbon atoms n of which the fullerene C.sub.n is composed is 60, 70, 76, 78, 82, 84, 90, 94 or 96, very preferably 60 or 70.

[0174] The fullerene C.sub.n in formula XII and its subformulae is preferably selected from carbon based fullerenes, endohedral fullerenes, or mixtures thereof, very preferably from carbon based fullerenes.

[0175] Suitable and preferred carbon based fullerenes include, without limitation, (C.sub.60-lh)[5,6]fullerene, (C.sub.70-D5h)[5,6]fullerene, (C.sub.76-D2*)[5,6]fullerene, (C.sub.84-D2*)[5,6]fullerene, (C.sub.84-D2d)[5,6]fullerene, or a mixture of two or more of the aforementioned carbon based fullerenes.

[0176] The endohedral fullerenes are preferably metallofullerenes. Suitable and preferred metallofullerenes include, without limitation, La@C.sub.60, La@C.sub.82, Y@C.sub.82, Sc.sub.3N@C.sub.80, Y.sub.3N@C.sub.80, Sc.sub.3C.sub.2@C.sub.80 or a mixture of two or more of the aforementioned metallofullerenes.

[0177] Preferably the fullerene C.sub.n is substituted at a [6,6] and/or [5,6] bond, preferably substituted on at least one [6,6] bond.

[0178] Primary and secondary adduct, named “Adduct” in formula XII and its subformulae, is preferably selected from the following formulae

##STR00059## ##STR00060## ##STR00061##

wherein C.sub.n is as defined in formula XII, [0179] Ar.sup.S1, Ar.sup.S2 denote, independently of each other, an arylene or heteroarylene group with 5 to 20, preferably 5 to 15, ring atoms, which is mono- or polycyclic, and which is optionally substituted by one or more identical or different substituents having one of the meanings of R.sup.S as defined above and below, and

[0180] R.sup.S1R.sup.S2, R.sup.S3, R.sup.S4, R.sup.S5 and R.sup.S6 independently of each other denote H, CN or have one of the meanings of R.sup.S as defined above and below.

[0181] Preferred compounds of formula XII are selected from the following subformulae:

##STR00062## ##STR00063##

wherein C.sub.n, k and l are as defined in formula XII, and

[0182] R.sup.S1, R.sup.S2, R.sup.S3, R.sup.S4 R.sup.S5 and R.sup.S6 independently of each other denote H or have one of the meanings of R.sup.S as defined above and below.

[0183] Also preferably the polymer according to the present invention is blended with other type of n-type semiconductor such as graphene, a metal oxide, like for example, ZnOx, TiOx, ZTO, MoOx, NiOx, quantum dots, like for example, CdSe or CdS, or a conjugated polymer, like for example a polynaphthalenediimide or polyperylenediimide as described, for example, in WO2013142841 A1 to form the active layer in an OPV or OPD device.

[0184] The device preferably further comprises a first transparent or semi-transparent electrode on a transparent or semi-transparent substrate on one side of the active layer, and a second metallic or semi-transparent electrode on the other side of the active layer.

[0185] Preferably, the active layer according to the present invention is further blended with additional organic and inorganic compounds to enhance the device properties. For example, metal particles such as Au or Ag nanoparticules or Au or Ag nanoprism for enhancements in light harvesting due to near-field effects (i.e. plasmonic effect) as described, for example in Adv. Mater. 2013, 25 (17), 2385-2396 and Adv. Ener. Mater. 10.1002/aenm.201400206, a molecular dopant such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane for enhancement in photoconductivity as described, for example in Adv. Mater. 2013, 25(48), 7038-7044, or a stabilising agent consisting of a UV absorption agent and/or anti-radical agent and/or antioxidant agent such as 2-hydroxybenzophenone, 2-hydroxyphenylbenzotriazole, oxalic acid anilides, hydroxyphenyl triazines, merocyanines, hindered phenol, N-aryl-thiomorpholine, N-aryl-thiomorpholine-1-oxide, N-aryl-thiomorpholine-1,1-dioxide, N-aryl-thiazolidine, N-aryl-thiazolidine-1-oxide, N-aryl-thiazolidine-1,1-dioxide and 1,4-diazabicyclo[2.2.2]octane as described, for example, in WO2012095796 A1 and in WO2013021971 A1.

[0186] The device preferably may further comprise a UV to visible photo-conversion layer such as described, for example, in J. Mater. Chem. 2011, 21, 12331 or a NIR to visible or IR to NIR photo-conversion layer such as described, for example, in J. Appl. Phys. 2013, 113, 124509.

[0187] Further preferably the OPV or OPD device comprises, between the active layer and the first or second electrode, one or more additional buffer layers acting as hole transporting layer and/or electron blocking layer, which comprise a material such as metal oxides, like for example, ZTO, MoO.sub.x, NiO.sub.x, a doped conjugated polymer, like for example PEDOT:PSS and polypyrrole-polystyrene sulfonate (PPy:PSS), a conjugated polymer, like for example polytriarylamine (PTAA), an organic compound, like for example substituted triaryl amine derivatives such as N,N′-diphenyl-N,N′-bis(1-naphthyl)(1,1′-biphenyl)-4,4′diamine (NPB), N,N′-diphenyl-N,N′-(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD), graphene based materials, like for example, graphene oxide and graphene quantum dots or alternatively as hole blocking layer and/or electron transporting layer, which comprise a material such as metal oxide, like for example, ZnO.sub.x, TiO.sub.x, AZO (aluminium doped zinc oxide), a salt, like for example LiF, NaF, CsF, a conjugated polymer electrolyte, like for example poly[3-(6-trimethylammoniumhexyl)thiophene], poly(9,9-bis(2-ethylhexyl)-fluorene]-b-poly[3-(6-trimethylammoniumhexyl)thiophene], or poly[(9,9-bis(3″-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)], a polymer, like for example poly(ethyleneimine) or crosslinked N-containing compound derivatives or an organic compound, like for example tris(8-quinolinolato)-aluminium(III) (Alq.sub.3), phenanthroline derivative or C.sub.60 or C.sub.70 based fullerenes, like for example, as described in Adv. Energy Mater. 2012, 2, 82-86.

[0188] In a blend or mixture of a polymer according to the present invention with a fullerene or modified fullerene, the ratio polymer:fullerene is preferably from 5:1 to 1:5 by weight, more preferably from 2:1 to 1:3 by weight, most preferably 1:1 to 1:2 by weight. A polymeric binder may also be included, from 5 to 95% by weight. Examples of binder include polystyrene (PS), polypropylene (PP) and polymethylmethacrylate (PMMA).

[0189] To produce thin layers in BHJ OPV devices the polymers, polymer blends or mixtures of the present invention may be deposited by any suitable method. Liquid coating of devices is more desirable than vacuum deposition techniques. Solution deposition methods are especially preferred. The formulations of the present invention enable the use of a number of liquid coating techniques. Preferred deposition techniques include, without limitation, dip coating, spin coating, ink jet printing, nozzle printing, letter-press printing, screen printing, gravure printing, doctor blade coating, roller printing, reverse-roller printing, offset lithography printing, dry offset lithography printing, flexographic printing, web printing, spray coating, curtain coating, brush coating, slot dye coating or pad printing. For the fabrication of OPV devices and modules area printing method compatible with flexible substrates are preferred, for example slot dye coating, spray coating and the like.

[0190] Suitable solutions or formulations containing a blend or mixture of a polymer according to the present invention with a fullerene or modified fullerene like PCBM are preferably prepared. In the preparation of such a formulation, suitable solvents are preferably selected to ensure full dissolution of both component, p-type and n-type and take into account the boundary conditions (for example rheological properties) introduced by the chosen printing method.

[0191] Organic solvent are generally used for this purpose. Typical solvents can be aromatic solvents, halogenated solvents or chlorinated solvents, including chlorinated aromatic solvents. Examples include, but are not limited to dichloromethane, trichloromethane, tetrachloromethane, chlorobenzene, o-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, 1,8-diiodooctane, 1-chloronaphthalene, 1,8-octane-dithiol, anisole, 2,5-di-methylanisole, 2,4-dimethylanisole, toluene, o-xylene, m-xylene, p-xylene, mixture of xylene o-, m-, and p-isomers, 1,2,4-trimethylbenzene, mesitylene, cyclohexane, 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, tetraline, decaline, indane, 1-methyl-4-(1-methylethenyl)-cyclohexene (d-Limonene), 6,6-dimethyl-2-methylenebicyclo[3.1.1]heptanes (β-pinene), methyl benzoate, ethyl benzoate, nitrobenzene, benzaldehyde, tetrahydrofuran, 1,4-dioxane, 1,3-dioxane, morpholine, acetone, methylethylketone, ethyl acetate, n-butyl acetate, N,N-dimethylformamide, dimethylacetamide, dimethylsulfoxide and/or mixtures thereof.

[0192] The OPV device can for example be of any type known from the literature (see e.g. Waldauf et al., Appl. Phys. Lett., 2006, 89, 233517).

[0193] A first preferred OPV device according to the invention comprises the following layers (in the sequence from bottom to top): [0194] optionally a substrate, [0195] a high work function electrode, preferably comprising a metal oxide, like for example ITO and FTO, serving as anode, [0196] an optional conducting polymer layer or hole transport layer, preferably comprising an organic polymer or polymer blend, for example PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate), substituted triaryl amine derivatives, for example, TBD (N,N′-dyphenyl-N—N′-bis(3-methylphenyl)-1,1′biphenyl-4,4′-diamine) or NBD (N,N′-dyphenyl-N—N′-bis(1-napthylphenyl)-1,1′biphenyl-4,4′-diamine), [0197] a layer, also referred to as “active layer”, comprising of at least one p-type and at least one n-type organic semiconductor, which can exist for example as a p-type/n-type bilayer or as distinct p-type and n-type layers, or as blend or p-type and n-type semiconductor, forming a BHJ, [0198] optionally a layer having electron transport properties, for example comprising LiF, TiO.sub.x, ZnO.sub.x, PFN, a poly(ethyleneimine) or crosslinked nitrogen containing compound derivatives or a phenanthroline derivatives [0199] a low work function electrode, preferably comprising a metal like for example aluminum, serving as cathode, [0200] wherein at least one of the electrodes, preferably the anode, is transparent to visible and/or NIR light, and [0201] wherein at least one p-type semiconductor is a polymer according to the present invention.

[0202] A second preferred OPV device according to the invention is an inverted OPV device and comprises the following layers (in the sequence from bottom to top): [0203] optionally a substrate, [0204] a high work function metal or metal oxide electrode, comprising for example ITO and FTO, serving as cathode, a layer having hole blocking properties, preferably comprising a metal oxide like TiO.sub.x or ZnO.sub.x, or comprising an organic compound such as polymer like poly(ethyleneimine) or crosslinked nitrogen containing compound derivatives or phenanthroline derivatives, [0205] an active layer comprising at least one p-type and at least one n-type organic semiconductor, situated between the electrodes, which can exist for example as a p-type/n-type bilayer or as distinct p-type and n-type layers, or as blend or p-type and n-type semiconductor, forming a BHJ, [0206] an optional conducting polymer layer or hole transport layer, preferably comprising an organic polymer or polymer blend, for example of PEDOT:PSS or substituted triaryl amine derivatives, for example, TBD or NBD, [0207] an electrode comprising a high work function metal like for example silver, serving as anode, [0208] wherein at least one of the electrodes, preferably the cathode, is transparent to visible and/or NIR light, and [0209] wherein at least one p-type semiconductor is a polymer according to the present invention.

[0210] In the OPV devices of the present invention the p-type and n-type semiconductor materials are preferably selected from the materials, like the polymer/fullerene systems or polymer/polymer systems, as described above

[0211] When the active layer is deposited on the substrate, it forms a BHJ that phase separates at nanoscale level. For discussion on nanoscale phase separation see Dennler et al, Proceedings of the IEEE, 2005, 93 (8), 1429 or Hoppe et al, Adv. Func. Mater, 2004, 14(10), 1005. An optional annealing step may be then necessary to optimize blend morpohology and consequently OPV device performance.

[0212] Another method to optimize device performance is to prepare formulations for the fabrication of OPV(BHJ) devices that may include high boiling point additives to promote phase separation in the right way. 1,8-Octanedithiol, 1,8-diiodooctane, nitrobenzene, 1-chloronaphthalene, N,N-dimethylformamide, dimethylacetamide, dimethylsulfoxide and other additives have been used to obtain high-efficiency solar cells. Examples are disclosed in J. Peet, et al, Nat. Mater., 2007, 6, 497 or Fréchet et al. J. Am. Chem. Soc., 2010, 132, 7595-7597.

[0213] The polymers, polymer blends, mixtures and layers of the present invention are also suitable for use in an OFET as the semiconducting channel. Accordingly, the invention also provides an OFET comprising a gate electrode, an insulating (or gate insulator) layer, a source electrode, a drain electrode and an organic semiconducting channel connecting the source and drain electrodes, wherein the organic semiconducting channel comprises a polymer, polymer blend, mixture or organic semiconducting layer according to the present invention. Other features of the OFET are well known to those skilled in the art.

[0214] OFETs where an OSC material is arranged as a thin film between a gate dielectric and a drain and a source electrode, are generally known, and are described for example in U.S. Pat. No. 5,892,244, U.S. Pat. No. 5,998,804, U.S. Pat. No. 6,723,394 and in the references cited in the background section. Due to the advantages, like low cost production using the solubility properties of the compounds according to the invention and thus the processability of large surfaces, preferred applications of these FETs are such as integrated circuitry, TFT displays and security applications.

[0215] The gate, source and drain electrodes and the insulating and semiconducting layer in the OFET device may be arranged in any sequence, provided that the source and drain electrode are separated from the gate electrode by the insulating layer, the gate electrode and the semiconductor layer both contact the insulating layer, and the source electrode and the drain electrode both contact the semiconducting layer.

[0216] An OFET device according to the present invention preferably comprises: [0217] a source electrode, [0218] a drain electrode, [0219] a gate electrode, [0220] a semiconducting layer, [0221] one or more gate insulator layers, [0222] optionally a substrate.
wherein the semiconductor layer preferably comprises a polymer, polymer blend or mixture according to the present invention.

[0223] The OFET device can be a top gate device or a bottom gate device. Suitable structures and manufacturing methods of an OFET device are known to the skilled in the art and are described in the literature, for example in US 2007/0102696 A1.

[0224] The gate insulator layer preferably comprises a fluoropolymer, like e.g. the commercially available Cytop 809M® or Cytop 107M® (from Asahi Glass). Preferably the gate insulator layer is deposited, e.g. by spin-coating, doctor blading, wire bar coating, spray or dip coating or other known methods, from a formulation comprising an insulator material and one or more solvents with one or more fluoro atoms (fluorosolvents), preferably a perfluorosolvent. A suitable perfluorosolvent is e.g. FC75® (available from Acros, catalogue number 12380). Other suitable fluoropolymers and fluorosolvents are known in prior art, like for example the perfluoropolymers Teflon AF® 1600 or 2400 (from DuPont) or Fluoropel® (from Cytonix) or the perfluorosolvent FC 43® (Acros, No. 12377). Especially preferred are organic dielectric materials having a low permittivity (or dielectric contant) from 1.0 to 5.0, very preferably from 1.8 to 4.0 (“low k materials”), as disclosed for example in US 2007/0102696 A1 or U.S. Pat. No. 7,095,044.

[0225] In security applications, OFETs and other devices with semiconducting materials according to the present invention, like transistors or diodes, can be used for RFID tags or security markings to authenticate and prevent counterfeiting of documents of value like banknotes, credit cards or ID cards, national ID documents, licenses or any product with monetry value, like stamps, tickets, shares, cheques etc.

[0226] Alternatively, the polymers, polymer blends and mixtures according to the invention can be used in OLEDs, e.g. as the active display material in a flat panel display applications, or as backlight of a flat panel display like e.g. a liquid crystal display. Common OLEDs are realized using multilayer structures. An emission layer is generally sandwiched between one or more electron-transport and/or hole-transport layers. By applying an electric voltage electrons and holes as charge carriers move towards the emissive layer where their recombination leads to the excitation and hence luminescence of the lumophor units contained in the emission layer.

[0227] The polymers, polymer blends and mixtures according to the invention can be employed in one or more of a buffer layer, electron or hole transport layer, electron or hole blocking layer and emissive layer, corresponding to their electrical and/or optical properties. Furthermore their use within the emissive layer is especially advantageous, if the compounds, materials and films according to the invention show electroluminescent properties themselves or comprise electroluminescent groups or compounds. The selection, characterization as well as the processing of suitable monomeric, oligomeric and polymeric compounds or materials for the use in OLEDs is generally known by a person skilled in the art, see, e.g., Müller et al, Synth. Metals, 2000, 111-112, 31-34, Alcala, J. Appl. Phys., 2000, 88, 7124-7128 and the literature cited therein.

[0228] According to another use, the polymers, polymer blends and mixtures according to this invention, especially those showing photoluminescent properties, may be employed as materials of light sources, e.g. in display devices, as described in EP 0 889 350 A1 or by C. Weder et al., Science, 1998, 279, 835-837.

[0229] A further aspect of the invention relates to both the oxidised and reduced form of a polymer according to this invention. Either loss or gain of electrons results in formation of a highly delocalised ionic form, which is of high conductivity. This can occur on exposure to common dopants. Suitable dopants and methods of doping are known to those skilled in the art, e.g. from EP 0 528 662, U.S. Pat. No. 5,198,153 or WO 96/21659.

[0230] The doping process typically implies treatment of the semiconductor material with an oxidating or reducing agent in a redox reaction to form delocalised ionic centres in the material, with the corresponding counterions derived from the applied dopants. Suitable doping methods comprise for example exposure to a doping vapor in the atmospheric pressure or at a reduced pressure, electrochemical doping in a solution containing a dopant, bringing a dopant into contact with the semiconductor material to be thermally diffused, and ion-implantantion of the dopant into the semiconductor material.

[0231] When electrons are used as carriers, suitable dopants are for example halogens (e.g., I.sub.2, Cl.sub.2, Br.sub.2, ICl, ICl.sub.3, IBr and IF), Lewis acids (e.g., PF.sub.5, AsF.sub.5, SbF.sub.5, BF.sub.3, BCl.sub.3, SbCl.sub.5, BBr.sub.3 and SO.sub.3), protonic acids, organic acids, or amino acids (e.g., HF, HCl, HNO.sub.3, H.sub.2SO.sub.4, HClO.sub.4, FSO.sub.3H and ClSO.sub.3H), transition metal compounds (e.g., FeCl.sub.3, FeOCl, Fe(ClO.sub.4).sub.3, Fe(4-CH.sub.3C.sub.6H.sub.4SO.sub.3).sub.3, TiCl.sub.4, ZrCl.sub.4, HfCl.sub.4, NbF.sub.5, NbCl.sub.5, TaCl.sub.5, MoF.sub.5, MoCl.sub.5, WF.sub.5, WCl.sub.6, UF.sub.6 and LnCl.sub.3 (wherein Ln is a lanthanoid), anions (e.g., Cl.sup.−, Br, I.sup.−, I.sub.3.sup.−, HSO.sub.4.sup.−, SO.sub.4.sup.2−, NO.sub.3.sup.−, ClO.sub.4.sup.−, BF.sub.4.sup.−, PF.sub.6.sup.−, AsF.sub.6.sup.−, SbF.sub.6.sup.−, FeCl.sub.4.sup.−, Fe(CN).sub.6.sup.3−, and anions of various sulfonic acids, such as aryl-SO.sub.3.sup.−). When holes are used as carriers, examples of dopants are cations (e.g., H.sup.+, Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+ and Cs.sup.+), alkali metals (e.g., Li, Na, K, Rb, and Cs), alkaline-earth metals (e.g., Ca, Sr, and Ba), O.sub.2, XeOF.sub.4, (NO.sub.2.sup.+) (SbF.sub.6.sup.−), (NO.sub.2.sup.+) (SbCl.sub.6.sup.−), (NO.sub.2.sup.+)(BF.sub.4.sup.−), AgClO.sub.4, H.sub.2IrCl.sub.6, La(NO.sub.3).sub.3.6H.sub.2O, FSO.sub.2OOSO.sub.2F, Eu, acetylcholine, R.sub.4N.sup.+, (R is an alkyl group), R.sub.4P.sup.+ (R is an alkyl group), R.sub.6As.sup.+ (R is an alkyl group), and R.sub.3S.sup.+ (R is an alkyl group).

[0232] The conducting form of a polymer of the present invention can be used as an organic “metal” in applications including, but not limited to, charge injection layers and ITO planarising layers in OLED applications, films for flat panel displays and touch screens, antistatic films, printed conductive substrates, patterns or tracts in electronic applications such as printed circuit boards and condensers.

[0233] The polymers, polymer blends and mixtures according to the present invention may also be suitable for use in organic plasmon-emitting diodes (OPEDs), as described for example in Koller et al., Nat. Photonics, 2008, 2, 684.

[0234] According to another use, the polymers according to the present invention can be used alone or together with other materials in or as alignment layers in LCD or OLED devices, as described for example in US 2003/0021913. The use of charge transport polymers according to the present invention can increase the electrical conductivity of the alignment layer. When used in an LCD, this increased electrical conductivity can reduce adverse residual dc effects in the switchable LCD cell and suppress image sticking or, for example in ferroelectric LCDs, reduce the residual charge produced by the switching of the spontaneous polarisation charge of the ferroelectric LCs. When used in an OLED device comprising a light emitting material provided onto the alignment layer, this increased electrical conductivity can enhance the electroluminescence of the light emitting material. The polymers according to the present invention having mesogenic or liquid crystalline properties can form oriented anisotropic films as described above, which are especially useful as alignment layers to induce or enhance alignment in a liquid crystal medium provided onto said anisotropic film. The polymers according to the present invention may also be combined with photoisomerisable compounds and/or chromophores for use in or as photoalignment layers, as described in US 2003/0021913 A1.

[0235] According to another use the polymers, polymer blends and mixtures according to the present invention, especially their water-soluble derivatives (for example with polar or ionic side groups) or ionically doped forms, can be employed as chemical sensors or materials for detecting and discriminating DNA sequences. Such uses are described for example in L. Chen, D. W. McBranch, H. Wang, R. Helgeson, F. Wudl and D. G. Whitten, Proc. Natl. Acad. ScL U.S.A., 1999, 96, 12287; D. Wang, X. Gong, P. S. Heeger, F. Rininsland, G. C. Bazan and A. J. Heeger, Proc. Natl. Acad. Sci. U.S.A., 2002, 99, 49; N. DiCesare, M. R. Pinot, K. S. Schanze and J. R. Lakowicz, Langmuir, 2002, 18, 7785; D. T. McQuade, A. E. Pullen, T. M. Swager, Chem. Rev., 2000, 100, 2537.

[0236] Unless the context clearly indicates otherwise, as used herein plural forms of the terms herein are to be construed as including the singular form and vice versa.

[0237] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of the words, for example “comprising” and “comprises”, mean “including but not limited to”, and are not intended to (and do not) exclude other components.

[0238] It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the invention. Each feature disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0239] All of the features disclosed in this specification may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination).

[0240] Above and below, unless stated otherwise percentages are percent by weight and temperatures are given in degrees Celsius. The values of the dielectric constant ∈ (“permittivity”) refer to values taken at 20° C. and 1,000 Hz.

[0241] The invention will now be described in more detail by reference to the following examples, which are illustrative only and do not limit the scope of the invention.

EXAMPLES

A) Polymer Examples

Example 1—Polymer P1 (EH=2-ethl hexyl)

[0242] ##STR00064##

[0243] To a 20 cm.sup.3 microwave vial is added 7,7-bis-(2-ethyl-hexyl)-2,5-bis-trimethylstannanyl-7H-3,4-dithia-7-sila-cyclopenta[a]pentalene (148.9 mg; 0.2000 mmol; 1.000 eq.), 4,4-bis-(2-ethyl-hexyl)-2,6-bis-trimethylstannanyl-4H-cyclopenta[2,1-b;3,4-b′]dithiophene (145.7 mg; 0.2000 mmol; 1.000 eq.), 4,7-dibromo-5,6-difluoro-benzo[1,2,5]thiadiazole (128.0 mg; 0.3880 mmol; 1.9400 eq.), tris(dibenzylideneacetone)-dipalladium(0) (7.0 mg; 0.0080 mmol; 0.0400 eq.) and tri-o-tolyl-phosphine (14.0 mg; 0.0460 mmol; 0.230 eq.). The vessel is evacuated and nitrogen purged three times and degassed toluene (20.00 cm.sup.3) is added before the reaction mixture is degassed further for 10 minutes. The reaction mixture is heated to 100° C. and stirred at this temperature for 4 hours and 50 minutes. The reaction mixture is allowed to cool to 65° C. and precipitated into stirred methanol (100 cm.sup.3). The polymer is collected by filtration and washed with methanol (2×50 cm.sup.3) to give a solid. The polymer is subjected to sequential Soxhlet extraction with acetone, petroleum ether (40-60° C.), cyclohexane, chloroform and chlorobenzene. The chloroform and chlorobenzene fractions are concentrated in vacuo to 20 cm.sup.3, precipitated into stirred methanol (250 cm.sup.3) and collected by filtration to give black solids.

[0244] Chloroform solids (75.0 mg, Yield: 32%), GPC (50° C., chlorobenzene) M.sub.n=33.5 kg.Math.mol.sup.−1, M.sub.w=124.8 kg.Math.mol.sup.−1, PDI=3.73.

[0245] Chlorobenzene solids (139.0 mg, Yield: 60%), GPC (50° C., chlorobenzene) M.sub.n=95.9 kg.Math.mol.sup.−1, M.sub.w=304.6 kg.Math.mol.sup.−1, PDI=3.18.

Example 2—Polymer P2

[0246] ##STR00065##

[0247] To a 20 cm.sup.3 microwave vial is added 7,7-bis-(2-ethyl-hexyl)-2,5-bis-trimethylstannanyl-7H-3,4-dithia-7-sila-cyclopenta[a]pentalene (297.8 mg; 0.4000 mmol; 2.000 eq.), 4,4-bis-(2-ethyl-hexyl)-2,6-bis-trimethylstannanyl-4H-cyclopenta[2,1-b;3,4-b′]dithiophene (145.7 mg; 0.2000 mmol; 1.000 eq.), 4,7-dibromo-5,6-difluoro-benzo[1,2,5]thiadiazole (192.0 mg; 0.5820 mmol; 2.9100 eq.), tris(dibenzylideneacetone)dipalladium(0) (7.0 mg; 0.0080 mmol; 0.0400 eq.) and tri-o-tolyl-phosphine (14.0 mg; 0.0460 mmol; 0.230 eq.). The vessel is evacuated and nitrogen purged three times and degassed toluene (20.00 cm.sup.3) is added before the reaction mixture is degassed further for 10 minutes. The reaction mixture is heated to 100° C. and stirred at this temperature for 1 hour and 50 minutes. The reaction mixture is allowed to cool to 65° C. and precipitated into stirred methanol (100 cm.sup.3). The polymer is collected by filtration and washed with methanol (2×50 cm.sup.3) to give a solid. The polymer is subjected to sequential Soxhlet extraction with acetone, petroleum ether (40-60° C.), cyclohexane, chloroform and chlorobenzene. The chloroform and chlorobenzene fractions are concentrated in vacuo to 20 cm.sup.3, precipitated into stirred methanol (250 cm.sup.3) and collected by filtration to give black solids. Chloroform solids (36.0 mg), GPC (50° C., chlorobenzene) M.sub.n=15.8 kg.Math.mol.sup.−1, M.sub.w=49.3 kg.Math.mol.sup.−1, PDI=3.12.

[0248] Chlorobenzene solids (42.0 mg), GPC (50° C., chlorobenzene) M.sub.n=57.6 kg.Math.mol.sup.−1, M.sub.w=436.5 kg.Math.mol.sup.−1, PDI=7.58.

Comparative Example 1—Polymer C1

[0249] ##STR00066##

[0250] To a 20 cm.sup.3 microwave vial is added 7,7-bis-(2-ethyl-hexyl)-2,5-bis-trimethylstannanyl-7H-3,4-dithia-7-sila-cyclopenta[a]pentalene (297.8 mg; 0.4000 mmol; 1.000 eq.), 4,7-dibromo-5,6-difluoro-benzo[1,2,5]thiadiazole (128.0 mg; 0.3880 mmol; 0.9700 eq.), tris(dibenzylideneacetone)-dipalladium(0) (7.0 mg; 0.0080 mmol; 0.0200 eq.) and tri-o-tolyl-phosphine (14.0 mg; 0.0460 mmol; 0.110 eq.). The vessel is evacuated and nitrogen purged three times and degassed toluene (20.00 cm.sup.3) is added before the reaction mixture is degassed further for 10 minutes. The reaction mixture is heated to 100° C. and stirred at this temperature for 1 hour and 35 minutes. The reaction mixture is allowed to cool to 65° C. and precipitated into stirred methanol (100 cm.sup.3). The polymer is collected by filtration and washed with methanol (2×50 cm.sup.3) to give a solid. The polymer is subjected to sequential Soxhlet extraction with acetone, petroleum ether (40-60° C.), cyclohexane, chloroform and chlorobenzene. The chlorobenzene fraction is concentrated in vacuo to 20 cm.sup.3, precipitated into stirred methanol (250 cm.sup.3) and collected by filtration to give a black solid.

[0251] Chlorobenzene solids (34.0 mg, Yield: 14%), GPC (50° C., chlorobenzene) M.sub.n=5.4 kg.Math.mol.sup.−1, M.sub.w=10.2 kg.Math.mol.sup.−1, PDI=1.89.

[0252] Insoluble solids (161 mg, Yield: 69%).

Comparative Example 2—Polymer C2

[0253] ##STR00067##

[0254] PCPDTBT and its preparation are disclosed, for example, in US 2007/0017571 A1.

Comparative Example 3—Polymer C3

[0255] ##STR00068##

[0256] PDTSBT and its preparation are disclosed, for example, in J. Am. Chem. Soc., 2008, 130 (48), 16144-16145.

Comparative Example 4—Polymer C4

[0257] ##STR00069##

[0258] To a 1000 cm.sup.3 round bottom flask is added 7,7-bis-(2-ethyl-hexyl)-2,5-bis-trimethylstannanyl-7H-3,4-dithia-7-sila-cyclopenta[a]pentalene (4.20 g; 5.640 mmol; 4.82 eq.), 4,4-bis-(2-ethyl-hexyl)-2,6-bis-trimethylstannanyl-4H-cyclopenta[2,1-b;3,4-b′]dithiophene (0.85 g; 1.170 mmol; 1.00 eq.), 4,7-dibromo-5,6-difluoro-benzo[1,2,5]thiadiazole (1.87 g; 6.400 mmol; 5.47 eq.), tris(dibenzylideneacetone)dipalladium(0) (175.0 mg; 0.191 mmol; 0.163 eq.) and triphenylphosphine (440.0 mg; 1.678 mmol; 1.434 eq.). The vessel is evacuated and argon purged five times and degassed toluene (850 cm.sup.3) is added before the reaction mixture is degassed further for 15 minutes. The reaction mixture is heated to 120° C. and stirred at this temperature for 60 hours. The reaction mixture is concentrated in vacuo and redissolved in o-dichlorobenzene, washed with aqueous sodium diethyldithiocarbamate trihydrate solution (1000 cm.sup.3), water (1000 cm.sup.3) and concentrated in vacuo. The solution is then precipitated into stirred methanol (400 cm.sup.3) and collected by filtration. The polymer is subjected to sequential Soxhlet extraction with methanol, acetone, dichloromethane and 1,2-dichlorobenzene. The 1,2-dichlorobenzene fraction is concentrated in vacuo to 100 cm.sup.3, precipitated into stirred methanol (250 cm.sup.3) and collected by filtration to give a black solid.

[0259] 1,2-Dichlorobenzene solids (2.91 g, Yield: 79%), GPC (50° C., chlorobenzene) M.sub.n=20.9 kg.Math.mol.sup.−1, M.sub.w=46.3 kg.Math.mol.sup.−1, PDI=2.22.

B) Use Examples

Bulk Heterojunction Organic Photovoltaic Devices (OPVs).

[0260] Organic photovoltaic (OPV) devices are fabricated on pre-patterned ITO-glass substrates (13 Ω/sq.) purchased from LUMTEC Corporation. Substrates were cleaned using common solvents (acetone, iso-propanol, deionized-water) in an ultrasonic bath. A conducting polymer poly(ethylene dioxythiophene) doped with poly(styrene sulfonic acid) [Clevios VPAI 4083 (H. C. Starck)] is mixed in a 1:1 ratio with deionized-water. This solution was filtered using a 0.45 μm filter before spin-coating to achieve a thickness of 20 nm. Substrates were exposed to ozone prior to the spin-coating process to ensure good wetting properties. Films were then annealed at 140° C. for 30 minutes in a nitrogen atmosphere where they were kept for the remainder of the process. Active material solutions (i.e. polymer+PCBM) were prepared and stirred overnight to fully dissolve the solutes. Thin films were either spin-coated or blade-coated in a nitrogen atmosphere to achieve active layer thicknesses between 100 and 500 nm as measured using a profilometer. A short drying period followed to ensure removal of any residual solvent.

[0261] Typically, spin-coated films were dried at 23° C. for 10 minutes and blade-coated films were dried at 70° C. for 2 minutes on a hotplate. For the last step of the device fabrication, Ca (30 nm)/A1 (125 nm) cathodes were thermally evaporated through a shadow mask to define the cells. Current-voltage characteristics were measured using a Keithley 2400 SMU while the solar cells were illuminated by a Newport Solar Simulator at 100 mW.Math.cm-2 white light. The Solar Simulator was equipped with AM1.5G filters. The illumination intensity was calibrated using a Si photodiode. All the device preparation and characterization is done in a dry-nitrogen atmosphere.

[0262] Power conversion efficiency is calculated using the following expression

[00001]$\eta =\frac{V_{\mathrm{oc}}\times J_{\mathrm{sc}}\times \mathrm{FF}}{P_{\mathrm{in}}}$

where FF is defined as

[00002]$\mathrm{FF}=\frac{V_{\max }\times J_{\max }}{V_{\mathrm{oc}}\times J_{\mathrm{sc}}}$

[0263] OPV device characteristics for a blend of polymer and PC.sub.60BM (unless stated otherwise) coated from an o-dichlorobenzene solution at a total solid concentration are shown in Table 1.

TABLE-US-00001 TABLE 1 Photovoltaic cell characteristics. ratio conc.sup.n Voc Jsc FF PCE Polymer Polymer:PCBM mg .Math. ml.sup.−1 mV mA .Math. cm.sup.−2 % % Polymer 1.00:2.00 30 767 −10.99 42 3.57 P1 Polymer 1.00:2.00 30 716 −12.07 47 4.08 P2 Polymer No device performance measurable C1 Polymer 1.00:2.00 30 545 −5.39 34 0.98 C2 Polymer 1.00:2.00 30 574 −7.90 47 2.13 C3 Polymer 1.00:2.00 30 622 −9.20 59 3.38 C4

[0264] It can be seen that polymer examples P1 and P2 according to the invention show a significant increase in Voc compared to the non-fluorinated comparisons C2-C4. It can also be seen that the random polymers P1 and P2 show increased solubility compared to the alternating and regioregular comparative polymers C1-C3. By combining randomisation with fluorination, as seen in polymer P2, it is possible to improve Voc and solubility simultaneously whilst maintaining good morphology in the BHJ blend.