Conjugated polymers and their use in optoelectronic devices

1. An organic photovoltaic device comprising an anode, a cathode, and in between the anode and the cathode a semiconductor component, the semiconductor component comprising an oligomeric or polymeric compound comprising in its backbone a first repeat unit of the formula:

wherein:

each Ar independently is a monocyclic aryl or heteroaryl group;

R a is selected from H, a C 1-40 alkyl group, a C 2-40 alkenyl group, a C 2-40 alkynyl group, and a C 1-40 haloalkyl group, wherein:

each of the C 1-40 alkyl group, the C 2-40 alkenyl group, the C 2-40 alkynyl group, the C 1-40 haloalkyl group, optionally can be substituted with 1-10 substituents independently selected from a halogen, —CN, NO 2 , OH, —NH 2 , —NH(C 1-20 alkyl), —N(C 1-20 alkyl) 2 , —S(O) 2 OH, —CHO, —C(O)—C 1-20 alkyl, —C(O)OH, —C(O)—OC 1-20 alkyl, —C(O)NH 2 , —C(O)NH—C 1-20 alkyl, —C(O)N(C 1-20 alkyl) 2 , —OC 1-20 alkyl, —SiH 3 , —SiH(C 1-20 alkyl) 2 , —SiH 2 (C 1-20 alkyl), and —Si(C 1-20 alkyl) 3 ; and

one or more non-adjacent —CH 2 — groups in the C 1-40 alkyl group, the C 2-40 alkenyl group, the C 2-40 alkynyl group, and the C 1-40 haloalkyl group can be replaced by a group independently selected from —O—, —S—, —NH—, —N(C 1-20 alkyl)-, —C(O)—, —C(O)O—, and —Si(C 1-20 alkyl) 2 —; and

each of R b and R c independently is selected from H and -L-R,

wherein:

L at each occurrence, independently is selected from O, S, and a covalent bond; and

R, at each occurrence, independently is a C 1-40 alkyl group;

wherein the oligomeric or polymeric compound comprises in its backbone a second repeat unit, the second repeat unit comprising (a) one or more optionally substituted polycyclic aryl or heteroaryl groups, (b) one or more optionally substituted monocyclic aryl or heteroaryl groups, and/or (c) one or more linear conjugated linkers.

2. The device of claim 1 , wherein the moiety:

is selected from:

3. The device of claim 1 , wherein the first repeat unit has the formula:

wherein R a is a C 6-40 alkyl group, and R b and R c independently are H or a C 6-40 alkyl group as defined in claim 1 .

4. The device of claim 1 , wherein R a is a C 6-40 alkyl group or a C 6-40 alkenyl group.

5. The device of claim 1 , wherein R a is a branched C 6-40 alkyl group.

6. The device of claim 1 , wherein the first repeat unit has the formula:

wherein R a is a C 6-40 alkyl group or a C 6-40 alkenyl group; and R c is H, a C 6-40 alkoxy group, or a C 6-40 alkylthio group.

7. The device of claim 1 , wherein the second repeat unit has the formula:

wherein:

X is N or CR 3 ;

Y is N or CR 4 ; and

each of R 1 , R 2 , R 3 , and R 4 independently is selected from H and -L-R, wherein L and R are as defined in claim 1 .

8. The device of claim 1 , wherein the oligomeric or polymeric compound has the formula:

where each R a is a branched C 6-40 alkyl group; each of R 1 and R 2 is a branched C 6-40 alkyl or alkoxy group optionally substituted with a silyl group; and n is an integer that ranges from 10 to 10,000.

9. The device of claim 1 , wherein the organic photovoltaic device is a bulk heterojunction photovoltaic device.

10. The device of claim 1 , wherein the semiconductor component is photoactive and comprises a blend material.

11. The device of claim 10 , wherein the blend material further comprises a fullerene compound in addition to the oligomeric or polymeric compound.

12. The device of claim 11 , wherein the fullerene compound is [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM).