Superior photovoltaic performance of BF4-doped perovskite rationalized by ab initio nonadiabatic molecular dynamics

Hybrid organic–inorganic metal halide perovskites have emerged as a new generation of photovoltaic devices due to their impressive performance. Many experiments show that a small amount of pseudohalide BF4 doping significantly enhances the performance of the most studied CH3NH3PbI3 compound. We demonstrate, using real-time time-dependent density functional theory and ab initio non-adiabatic molecular dynamics, that a 2% concentration of BF4 doping can reduce the anharmonicity of the soft inorganic lattice, weaken the electron–phonon interaction, suppress non-radiative electron–hole recombination, and finally result in an 80% enhancement of charge carrier lifetime in CH3NH3PbI3 perovskite. More than that, low concentration of BF4 doping can keep the suitable bandgap and strengthen the optical absorption, whereas high concentration doping would extremely increase the bandgap so that should be prohibited in perovskite solar cells. Our results rationalize why low concentration of BF4 doping can suppress nonradiative charge carrier recombination and greatly improve the photovoltaic performance in CH3NH3PbI3 perovskite.