Spin-Orbit Coupling Is the Key to Promote Asynchronous Photoinduced Charge Transfer of Two-Dimensional Perovskites

Two-dimensional (2D) perovskites are emerging as promising candidates for diverse optoelectronic applications because of low cost and excellent stability. In this work, we explore the electronic structures and interfacial properties of (4Tm)₂PbI₄ with both the collinear and noncollinear DFT (PBE and HSE06) methods. The results evidently manifest that explicitly considering the spin-orbit coupling (SOC) effects is necessary to attain correct band alignment of (4Tm)₂PbI₄ that agrees with recent experiments (Nat. Chem.2019, 11, 1151; Nature2020, 580, 614). The subsequent time-domain noncollinear DFT-based nonadiabatic carrier dynamics simulations with the SOC effects reveal that the photoinduced electron and hole transfer processes are asymmetric and associated with different rates. The differences are mainly ascribed to considerably different nonadiabatic couplings in charge of the electron and hole transfer processes. Shortly, our current work sheds important light on the mechanism of the interfacial charge carrier transfer processes of (4Tm)₂PbI₄. The importance of the SOC effects on correctly aligning the band states of (4Tm)₂PbI₄ may be generalized to similar organic-inorganic hybrid 2D perovskites having heavy Pb atoms.