A thin film semiconductor comprising a compound of formula I or II wherein: R1 and R2, at each occurrence, independently are selected from a C1-30 alkyl group, a C2-30 alkenyl group, a C2-30 alkynyl group and a C1-30 haloalkyl group, R3, R4, R5, and R6 independently are H or an electron-withdrawing group, wherein at least one of R3, R4, R5, and R6 is an electron-withdrawing group; and a non-conductive polymer.