Passivating Lead Halide Perovskites Using Pyridinium Salts with Superhalogen Atoms

Passivating lead halide perovskites using pyridinium salts has attracted enormous attention, but the excellent surface passivation of the halide perovskites has not been achieved by using only a pyridinium salt until now. Herein, passivating the (001) planes of the cubic CsPbI₃, CH₃NH₃PbI₃, and NH₂CHNH₂PbI₃ perovskites using the pyridinium salts of C₅NH₆X (X = Cl, Br, I, PF₆, ClO₄, or BF₄) is systematically studied by high-throughput first-principle calculations and ab initio molecular dynamics simulations. The results show that the excellent surface passivation of the three perovskites is achieved by the pyridinium salt of C₅NH₆BF₄ (i.e., shallow level, negative formation energy, unchanged band-edge construction, and stable dynamics property are obtained for the three passivated perovskites), which strongly imply that their devices can show excellent performances, such as long-term stability, low ion migration, and high efficiency. However, the C₅NH₆ClO₄ and C₅NH₆PF₆ pyridinium salts are only profitable for passivating the (001) PbI₂ plane of the three perovskites, and other C₅NH₆X pyridinium salts have adverse effects.