Regulating electrode potential offset in perovskite solar cells for boosting interfacial charge transfer

Abstract

In perovskite solar cells (PSCs), the interfacial charge transfer has been adjusted by band offset to improve the device performance. However, the band offset cannot explain some abnormal phenomena of interfacial charge transfer. In this study, we adjusted electrode potential offset (ΔEPO) at the perovskite/hole transport layer (HTL) interface by employing different side chains HTLs, which increased the device efficiency from 0.6% to 18.1%. We also investigated the relation of chemical reaction kinetics at perovskite/HTL interfaces and the ΔEPO by in-situ FTIR, NMR, theoretical calculations and electrochemical measurements. Accordingly, we proposed ΔEPO as a driving force descriptor for interface charge transfer in the PSCs for the first time. These results deepen the understanding on the interfacial charge transfer, and offer a new design principle of the interface in the PSCs.