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)(2)PbI4 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)(2)PbI4 perovskites. This behavior is primarily governed by a low-frequency vibration mode around similar to 200 cm(-1). These calculations provide important insights into the potential for atomically modulating carrier behaviors to achieve excellent photovoltaic properties.