Conjugated Polymers Based on Benzo[2,1-b:3,4-b']dithiophene with Low-Lying Highest Occupied Molecular Orbital Energy Levels for Organic Photovoltaics

摘要

Fusing bithiophene units with a benzo moiety, benzo[2,1-6:3,4-b']dithiophene (BDT), was projected by theoretical calculations to lower the highest occupied molecular orbital (HOMO) energy level of the resulting polymers compared with that of the bithiophene unit, which would enhance the open circuit voltage of bulk heterojunction photovoltaic cells fabricated from BDT-based polymers blended with PCBM. The homopolymer of BDT (HMPBDT) and alternating copolymer of BDT with 2,1,3-benzothiadiazole (PBDT-BT)