A polymer comprising: In this embodiment, R′ and R″, can be independently selected from the group consisting of: a halogen, a substituted alkyl, an unsubstituted alkyl, a substituted aryl, and an unsubstituted aryl. Additionally, X1 and X2 can be independently selected from the group consisting of: O, S, Se, N—R, and Si—R—R. Lastly, Ar and Ar′ can be identical or different and can be independently selected from the group consisting of: a substituted aryl, and an unsubstituted aryl.