Divalent hard Lewis acid doped CsPbBr3 films for 9.63%-efficiency and ultra-stable all-inorganic perovskite solar cells

Substitution of Pb²⁺ sites with smaller isovalent ions is used to optimize the crystal lattice of inorganic CsPbBr₃ perovskite through releasing lattice strain, increasing the formation energy of vacancies and tuning the bandgap energy distribution.