From benzobisthiadiazole, thiadiazoloquinoxaline to pyrazinoquinoxaline based polymers: effects of aromatic substituents on the performance of organic photovoltaics

Abstract

Here we report the syntheses of low bandgap polymers based on benzobisthiadiazole (BBT), thiadiazoloquinoxaline (TQ) and pyrazinoquinoxaline (PQ) core structures with different aromatic substituents. The effects of changing core structures from BBT to PQ and also substituents from biphenyl and bithienyl on the photophysical, electrochemical and morphology of the polymers were studied. These polymers were incorporated into solar cell devices as donors, with PC[71]BM as acceptors, and their device performances were correlated with their properties. It was found that the effect of these structural changes has significant consequences on the overall device performances.