Divalent hard Lewis acid doped CsPbBr 3 films for 9.63%-efficiency and ultra-stable all-inorganic perovskite solar cells

Substitution of Pb 2+ sites with smaller isovalent ions is used to optimize the crystal lattice of inorganic CsPbBr 3 perovskite through releasing lattice strain, increasing the formation energy of vacancies and tuning the bandgap energy distribution.