Side chain independent photovoltaic performance of thienopyrroledione conjugated donor–acceptor polymers

Abstract

Side chain engineering has been well studied as a functional handle for controlling the properties of conjugated polymers in OSC applications, with side chain alteration typically effecting a PCE change. In this work, we highlight a unique TPD-based donor polymer system which exhibits robust photovoltaic tolerance regardless of acceptor unit side chain. While alteration of the side chain bulk from a minimally sized substituent (methyl) to a bulky substituent (cyclohexylmethyl) results in different aggregation properties of the neat polymers and the microstructures of the polymer–fullerene blends, these differences surprisingly do not translate to changes in PCE. Due to the versatility of the TPD unit for modification and the device performance invariance to side chain, this TPD-based class of polymers could serve as an excellent donor test polymer for OSC blend tuning and other applications. The findings of this work present an avenue for polymer structure and BHJ morphology manipulation without any commonly observed variations in photovoltaic performance.