Polymer solar cells (PSCs) were fabricated using a ternary blend film consisting two conjugated polymers and a soluble fullerene derivative as the donor and acceptor materials, respectively. And, to compare ternary blend system, the single-component copolymers consisting of the repeating units of each of the copolymers, used in ternary blend solar cells, were designed and synthesized for use as the electron donor materials in binary blend solar cells. We systematically investigated the field-effect carrier mobilities and the optical, electrochemical, and photovoltaic properties of the copolymers. Under optimized conditions, the binary blend polymer systems showed power conversion efficiencies (PCEs) for the PSCs in the range 3.87-4.16% under AM 1.5 illumination (100 mW cm(-2)). All polymers exhibited similar PCEs that did not depend on the ratio of repeating units. The binary blend solar cell containing a single-component copolymer as the electron donor material performed better than the ternary blend solar cell in this work. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 4416-4424, 2011