Patent ID: 8841409

Claim:
A polymer comprising an electron-acceptor unit (A) and an electron-donor unit (D), wherein the electron-acceptor unit (A) comprises a bithiopheneimide moiety represented by the formula: wherein: L is selected from the group consisting of —O—, —S—, —Se—, —OC(O)—, —C(O)O—, a divalent C 1-20 alkyl group, a divalent C 1-20 haloalkyl group, and a covalent bond; and Ar is a C 6-20 aryl or 5-20 membered heteroaryl group substituted with 1-5 R a groups, wherein R a , at each occurrence, independently is selected from the group consisting of a halogen —CN, and L′R′, wherein L′, at each occurrence, is selected from —O—, —S—, —Se—, —C(O)—, —OC(O)—, —C(O)O—, and a covalent bond, and R′, at each occurrence, independently is selected from the group consisting of a C 1-40 alkyl group, a C 2-40 alkenyl group, a C 2-40 alkenyl group, and a C 1-40 haloalkyl group; provided that at least one of the R a groups substituted on the C 6-20 aryl or 5-20 membered heteroaryl group is a linear or branched C 6-40 alkyl group; and wherein the polymer has a degree of polymerization in the range of 2 to 10,000.