UV-Stable and Highly Efficient Perovskite Solar Cells by Employing Wide Band gap NaTaO 3 as an Electron-Transporting Layer.

Organic-inorganic halide perovskite solar cells (PSCs) still suffer from stability issues which are caused by possible erosions from moisture, ultraviolet (UV) light, heat, and so forth. An electron-transporting layer (ETL), that is, TiO ₂ , is a key component for state-of-the-art PSCs. However, UV-caused desorption of O ^2- in TiO ₂ would accelerate the degradation of PSCs. Herein, we explored perovskite oxide, NaTaO ₃ , for the first time as an alternative ETL in PSCs. NaTaO ₃ as an ETL can effectively avoid the damage from UV irradiation, inhibit the degradation of the perovskite layer, and improve the overall stability of the PSC. PSCs fabricated with NaTaO ₃ yielded a power conversion efficiency (PCE) of 21.07% with a retention of more than 80% of this initial PCE after 240 min UV irradiation in air while the reference device with a PCE of 20.16% can only retain about 53% of its initial PCE after the same testing condition. The developed stable perovskite oxide material of NaTaO ₃ provides the diversification of electron-selective contact for highly efficient and stable PSCs.