A facile method to enhance photovoltaic performance of benzodithiophene- isoindigo polymers by inserting bithiophene spacer

A series of conjugated polymers containing benzodithiophene as donor and isoindigo as acceptor with no, one, two and three thiophene spacer groups is synthesized and characterized. The polymer with bithiophene as a spacer has a superior efficiency of 7.31% in solar cells. This demonstrates an important design strategy to produce polymers for high-performance solar cells by inserting thiophene spacer groups. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.