Lanthanide Ions Doped CsPbBr₃ Halides for HTM‐Free 10.14%‐Efficiency Inorganic Perovskite Solar Cell with an Ultrahigh Open‐Circuit Voltage of 1.594 V

All‐inorganic cesium lead bromide (CsPbBr 3 ) perovskite solar cells have attracted enormous attention owing to their outstanding stability in comparison with organic–inorganic hybrid devices. The greatest weakness for inorganic CsPbBr 3 solar cells is their lower power conversion efficiencies, mainly arising from inferior light‐absorbance range and serious charge recombination at interfaces or within perovskite films. To address this issue, the lattice doping of lanthanide ions (Ln 3+ = La 3+ , Ce 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ , Tb 3+ , Ho 3+ , Er 3+ , Yb 3+ , and Lu 3+ ) into CsPbBr 3 films for all‐inorganic solar cells free of hole‐transporting materials and precious metal electrodes is presented. Arising from the enlarged grain size and prolonged carrier lifetimes upon incorporating Ln 3+ ions into perovskite lattice, the performances of these inorganic CsPbBr 3 solar cell devices are significantly enhanced, achieving a champion efficiency as high as 10.14% and an ultrahigh open‐circuit voltage of 1.594 V under one sun illumination. Meanwhile, the nearly unchanged efficiency upon persistent attack by 80% RH in air atmosphere over 110 d and enhanced thermal stability at 80 °C over 60 d provide new opportunities of promoting commercialization of all‐inorganic CsPbBr 3 perovskite solar cells.