Anion Confinement for Homogeneous Mixed Halide Perovskite Film Growth by Electrospray

Abstract Wide‐bandgap perovskites are promising absorbers for state‐of‐the‐art tandem solar cells to feasibly surpass Shockley–Queisser limit with low cost. However, the commonly used mixed halide perovskites suffer from poor stability; particularly, photoinduced phase segregation. Electrospray deposition is developed to bridge the gap of growth rate between iodide and bromide components during film growth by spatially confining the anion diffusion and eliminating the kinetic difference, which universally improves the initial homogeneity of perovskite films regardless of device architectures. It thus promotes the efficiency and stability of corresponding solar cells based on wide‐bandgap (1.68 eV) absorbers. Remarkable power conversion efficiencies (PCEs) of 21.44% and 20.77% are achieved in 0.08 cm² and 1.0 cm² devices, respectively. In addition, these devices maintain 90% of their initial PCE after 1550 h of stabilized power output (SPO) tracking upon one sun irradiation (LED) at room temperature.