Heteroatomic doping induces charge rearrangement to optimize carrier dynamics in 2D halide perovskites

It is well established that a number of techniques, including applied electric fields, interfacial engineering, structural torsion, and doping, can modulate the geometric and electronic structures of materials, thereby enhancing their photoelectronic properties in two-dimensional (2D) halide perovskites. Among these strategies, doping has proven to be an extremely effective approach; however, the precise mechanisms underlying this effect remain elusive. Herein, we systematically investigated how heteroatom doping, specifically using Sn and Bi dopants, influences the excited-state dynamics of 2D (MA)2PbI4 perovskites using ab initio calculations combined with real-time nonadiabatic molecular dynamics simulations. Our results indicate that the doped systems maintain the octahedral configuration characteristics of the parent material. Notably, doping leads to a significant electron–hole separation in real space, corresponding to an extended carrier lifetime of approximately 140–150 ns, compared to just 2.70 ns for pristine (MA)2PbI4 perovskites. This behavior is primarily governed by a low-frequency vibration mode around ∼200 cm−1. These calculations provide important insights into the potential for atomically modulating carrier behaviors to achieve excellent photovoltaic properties.