α-DTC70 fullerene performs significantly better than β-DTC70 as electron transporting material in perovskite solar cells

Abstract

In this work, two new C₇₀ isomers, α and β bis(2-(thiophen-2-yl)ethyl)-C₇₀-fullerene mono-adducts (DTC₇₀), were synthesized, characterized and used as electron transporting materials (ETMs) in perovskite solar cells (PSCs). Our results show that the α isomer improves both the J_sc and FF values of the devices, when compared to the results for the β-isomer and to those for phenyl-C₇₀-butyric acid methyl ester (PC₇₁BM), used as control. Devices based on α-DTC₇₀ achieved a power conversion efficiency (PCE) of 15.9%, which is higher than that observed with PC₇₁BM (15.1%).