A new linear D-A-D organic small molecule (M1), with triphenylamine as electron donor (D) unit and isoindigo (ID) as electron acceptor (A) unit, was synthesized by Stille coupling reactions. It exhibits broad and strong absorption (300-700 nm), a relatively low HOMO energy level (-5.30 eV), low band gap (1.69 eV), and moderate hole mobility (2.49x10(-4) cm(2)/Vs). Solution-processed small molecule bulk-heterojunction solar cells based on M1: PC61BM (1: 3, w/w) blend film exhibits a power conversion efficiency of 0.84 % with an open-circuit voltage (V-oc) of 0.78 V, under the illumination of AM1.5, 100 mW/cm(2).