We synthesized organic photovoltaic materials that have high molecular weight and good solubility. A new random copolymer named poly[carbazole-co-dithienylbenzothiadiazole-co-dithienylquinoxaline] (PC-TBT-TQ) was polymerized through the Suzuki coupling reaction. PC-TBT-TQ was dissolved in a common organic solvent, and its M-n indicates a high molecular weight of 216.2 kg/mol. According to the result of thermal analysis, very high thermal stability was observed, with an approximately 5 wt% weight loss at 440 degrees C. The optical band gap of PC-TBT-TQ (1.89 eV) is slightly higher than that of PCDTBT (1.87 eV). The HOMO and LUMO levels of PC-TBT-TQ (HOMO level: 5.45 eV, LUMO level: 3.56 eV) are similar to those of PCDTBT (HOMO level: 5.45 eV, LUMO level: 3.58 eV). The OPV properties of the polymer were assessed by fabricating bulk-heterojunction polymer solar cells in the ITO/PEDOT:PSS/active-layer/BaF2/Ba/Al structure. When PC-TBT-TQ and PC71 BM were fabricated in a 1:4 ratio, the open-circuit voltage (V-OC), short-circuit current (J(SC)), fill factor (FF) and power conversion efficiency (PCE) were 0.83 V, 9.5 mA/cm(2), 43.3% and 3.5%, respectively. (C) 2013 Elsevier B.V. All rights reserved.