A new and efficient push-pull organic semiconductor, DMM-TPA-Th-2-MMN, with a planar fused triphenylamine (DMM-TPA) donor and a methylene malononitrile (MMN) acceptor was synthesized. The planar semiconductor exhibited better p-type semiconducting performance with a power conversion efficiency of 4.04% in solution-processed small-molecule organic solar cells than did the tilted TPA-Th-2-MMN semiconductor, enhancing hole mobilities due to more favorable intermolecular pi-pi packing interactions. (C) 2013 Elsevier B.V. All rights reserved.