A SrGeO3 inorganic electron-transporting layer for high-performance perovskite solar cells

Abstract

Titanium dioxide (TiO₂) is usually used as an ETL in n–i–p structure PSCs. It requires high temperature preparation, which limits commercialization of PSCs. Herein, we present a perovskite oxide SrGeO₃ as a new and superior ETL which can directly replace TiO₂. We synthesized SrGeO₃ by a low temperature hydrothermal method and applied it as an ETL for the first time in PSCs. SrGeO₃ is an excellent candidate to serve as an ETL in PSCs owing to its excellent solution processability at low temperature. SrGeO₃ is about 2 times more conductive than TiO₂. In addition, the energy level of the SrGeO₃ thin film matches those of the other functional layers in the device, indicating the suitability of SrGeO₃ as an ETL in PSCs. Finally, the power conversion efficiency (PCE) of devices prepared by using the perovskite SrGeO₃ as an ETL reached 17.68% and demonstrated good stability.