A polymer comprising wherein Ar1 and Ar2 are optional and either the same or different and independently selected from an aryl group or an heteroaryl group. In this polymer, W is selected from the group consisting of: S, Se, O, and N-Q; and Q is selected from the group consisting of: a straight-chain or branched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, and a fused unsubstituted aromatic ring. Additionally, in the polymer, R4 and R5 are selected from the group consisting of: a straight-chain or branched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, and a fused unsubstituted aromatic ring; and x+y=1.