Bithiophene imide and benzodithiophene copolymers for efficient inverted polymer solar cells

Abstract

Bithiophene imide (BTI) and benzodithiophene (BDT) copolymers are synthesized for application in organic photovoltaic (OPV) cells. The electron deficiency of the BTI units leads to polymers with a low-lying HOMOs (5.6 eV). Inverted solar cells are fabricated to investigate the OPV performance of the BTI-based polymers and achieve power conversion efficiencies up to 5.5%, with substantial V ocs above 0.9 V which are among the highest V ocs reported to date for polymer/PCBM solar cells. The results indicate that the BTI is a promising building block for constructing polymer donors for OPV applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.