Controlled synthesis of nanocrystalline Nb:SrTiO3 electron transport layers for robust interfaces and stable high photovoltaic energy conversion efficiency in perovskite halide solar cells

Perovskite halides are of great attraction as efficient light absorption materials for solid-state solar cells, but the stability and photovoltaic energy conversion efficiency of perovskite solar cell (PSCs) are still limited by the interface structures and defects between their light-absorbing perovskite halides and electron transport layers (ETLs). Here, we report the ultraviolet (UV) light-induced degradation mechanism at the interfaces between perovskite halide and conventional TiO2 ETL materials, and provide a solution to overcome this drawback. UV-induced degradation is shown to be attributed to the formation of oxygen vacancies formed at the perovskite halide-ETL interface under UV light illumination, where the oxygen atoms released at the interface accelerate the decomposition of perovskite halide by inducing chemical reactions. Meanwhile, nanocrystalline SrTiO3 (STO) ETLs are revealed to be tunable in enabling high performance in PSCs under UV light illumination. Indeed, tuning the electronic str...