Introduction of a conjugated side chain as an effective approach to improving donor-acceptor photovoltaic polymersElectronic supplementary information (ESI) available. See DOI: 10.1039/c2ee23383e

We report a simple, effective approach to modifying two kinds of D-A type polymers; copolymerization with thiophene containing tris(thienylenevinylene) (TTV) conjugated side chain. The resulting copolymers, TTV1 and TTV2 , showed significant improvement (25% and 43%) of power conversion efficiency in comparison to the original polymers. The short-circuit current of TTV2 reached 22.6 mA cm −2 that is the highest record for organic photovoltaic devices to date. This design strategy opens up a new possibility to modify the existing D-A type photovoltaic polymers for better performance. Introduction of a tris(thienylenevinylene) conjugated side chain into two polymers significantly improved photocurrent and efficiency of organic photovoltaic devices.