Low temperature solution processed indium oxide thin films with reliable photoelectrochemical stability for efficient and stable planar perovskite solar cells

Organometallic halide-based perovskite solar cells (PSCs) have attracted significant research attention among the next-generation photovoltaic technologies, in which the electron transport layer (ETL) plays a crucial role in the PSC performances of power conversion efficiency and long-term stability. Herein, we proposed a low temperature solution-processing route to prepare indium oxide thin films on ITO substrates with an acetylacetone-chelated precursor, which exhibit better film morphology, well-aligned band structure, and enhanced electron extraction capacity. As a result, the PSC fabricated from the as-prepared indium oxide film as the ETL shows a promoted maximum efficiency of 15.30% and steady-state efficiency of 14.39%, which are a record for indium oxide-based PSCs. More significantly, the indium oxide film shows minimum photocatalytic activity compared with ZnO and TiO2 films, which leads to excellent light and shelf-life device stability. After storage in the dark for three months, the power conversion efficiency of the unsealed PSCs based on the indium oxide films degrades slightly, which retain approximately 94% of their peak efficiency.