Suppressing halide phase segregation in wide-bandgap perovskite film by co-doping strategy for high-performance and stable perovskite solar cells

Wide-bandgap perovskites formed by tuning the iodine/bromine ratio can be combined with narrow-bandgap silicon materials to construct tandem solar cells, thus overcoming the Shockley-Queissel limit. However, light-induced halide ion migration causes poor perovskite film quality and detrimental halide phase segregation in it. Herein, a facile co-doping strategy for wide-bandgap (FA0.65MA0.2Cs0.15)Pb(I0·8Br0.2)3 film is demonstrated, that is, Pb(SCN)2 and PEACl are synergistically incorporated into perovskite film to break through this hurdle. The proposed strategy not only enables high-quality perovskite films with larger grains, fewer grain boundaries, and high crystallinity, but also the two-dimensional (2D) perovskite formed at grain boundaries effectively suppresses halide phase separation and improves the hydrophobicity of the films. As a result, we achieved a power conversion efficiency (PCE) of 19.92% for the small-area (0.07 cm2) perovskite solar cells (PSCs) and 17.70% for modules with an active area of 10.00 cm2. And, the operational and long-term storage stability of the modules are improved, maintaining 76% of their initial efficiency after 150 h of exposure to an environment with a relative humidity of ∼40% and a temperature of ∼20 °C. Furthermore, a semitransparent device with a PCE of 19.51% and a four-terminal (4T) perovskite/silicon tandem solar cell with a PCE of 30.53%, were successfully obtained.