Homopolymers, Copolymers, and Blends Use of a regio-regular poly(3-substitutedthiophene) is described in which the 3-substitutent is an alkyl, aryl, or alkyl/aryl moiety with an oxygen substitution in either the ??- or ??-position of the 3-substituent or a hetero atom in either the ??- or ??-position of the 3-substituent including homopolymers and mixed systems such as copolymers and blends of the