Optimization of a SnO2-based electron transport layer using cerium oxide for efficient and stable perovskite solar cells

Abstract

Electron transport layer (ETL)/perovskite interface engineering is an effective strategy to improve the performance of perovskite solar cells. In this work, the surface morphology of SnO₂ was improved, and defects at the ETL/perovskite interface were passivated by introducing a CeO_x interlayer, which also avoids detrimental contact between the perovskite layer and indium tin oxide (ITO). In addition, owing to the suitable energy level positions and high electron mobility of CeO_x, its incorporation between SnO₂ and perovskite results not only in the formation of an ideal cascade energy level arrangement but also in the creation of two electron transport channels, which promote the extraction and transport of electrons, reduce charge accumulation at the interface, and consequently enhance the optoelectronic performance of the device. Finally, an efficiency of 20.23% was obtained for the optimized device based on CeO_x/SnO₂ under ambient conditions, with negligible hysteresis and enhanced long-term stability.