Anharmonicity-Driven Modulation of Carrier Lifetime and Mobility in BF 4 -Doped All-Inorganic CsPbX 3 (X = I, Br) Perovskites

Pseudohalide (such as BF 4 – ) doping has emerged as a crucial strategy for enhancing the photovoltaic performance of all-inorganic halide perovskite CsPbX 3 (X = I, Br) solar cells. Here, we employ density functional theory and ab initio nonadiabatic molecular dynamics to elucidate how BF 4 – doping modulates carrier dynamics through anharmonicity-driven mechanisms. We demonstrate that BF 4 – incorporation substantially enhances intrinsic anharmonicity (∼4.5-fold in CsPbI 3, >10-fold in CsPbBr 3 ), amplifying dynamic disorder that induces charge localization and reduces electron–phonon coupling. This mechanism extends nonradiative recombination lifetimes by 131% in CsPbI 3 and 47% in CsPbBr 3 . Critically, we reveal a nonmonotonic relationship between anharmonicity and carrier transport: whereas moderate anharmonicity enhancement improves electron mobility by 35% in CsPbI 3, excessive enhancement induces mobility degradation in CsPbBr 3 due to charge overlocalization. Our work establishes fundamental design principles connecting lattice anharmonicity to carrier lifetime and mobility, providing atomic-level insights for optimizing pseudohalide-doped perovskite optoelectronics.