Synthesis and photovoltaic properties of conjugated copolymers with benzo[1,2-b:4,5-b']dithiophene and bis(thiophene)phthalimide units

摘要

Two new donor/acceptor copolymers PBDTPhBT1 and PBDTPhBT2 with alternating benzodithiophene (BDT) and bisthiophene-phthalimide (PhBT) units were synthesized by Stille coupling reaction. The copolymers showed identical optical bandgaps of 1.98eV. The HOMO energy levels are -5.35 and -5.32eV for PBDTPhBT1 and PBDTPhBT2, respectively. The bulk heterojunction solar cell devices based on these copolymers as donors and PC_(71)BM as acceptor displayed high open-circuit voltages of 0.90-0.93V and achieved power conversion efficiency of 1.54% under the illumination of AM 1.5, 100mW·cm~(-2). Two new polymers PBDTPhBT1 and PBDTPhBT2 with alternating benzodithiophene (BDT) and bisthiophene-phthalimide (PhBT) units were synthesized and the solar cell devices based on these polymers as donors and PC_(71)BM as acceptor displayed high open circuit voltages of 0.90-0.93V.