Modulating magneto-photoluminescence effects in 3D lead halide perovskites via halide-component dependent Rashba spin–orbit coupling

Three-dimensional lead halide perovskites (3D LHPs) exhibit giant Rashba spin-orbit coupling (SOC) due to their inherent lattice asymmetry and heavy-metal composition; yet, the impact of Rashba SOC on the luminescence dynamic of 3D LHPs remains debated. Here, we utilize the magneto-photoluminescence (Magneto-PL) effects as an effective tool to reveal the underlying spin-related opto-physical process in 3D LHPs. We find that the magneto-PL effects of 3D LHPs CH3NH3Pb(Br/I/IxCl1-x)3 thin films are negative and tunable at room temperature, indicating the remarkable suppression of their PL emission intensity by magnetic fields. Moreover, the largest magneto-PL magnitude of -3.60% is realized in CH3NH3PbIxCl3-x thin film at a magnetic field strength of ±1 T; oppositely, in CH3NH3PbI3 thin film, it is merely -0.75%. Combining magneto-optical spectroscopy and crystallographic analysis of 3D LHP thin films, we attribute this phenomenon to the interplay of the Rashba SOC-driven spin mixing and Zeeman splitting between dark singlet and bright triplet excitons, promoting spin conversion from dark excitonic states to bright states. In addition, we demonstrate that the Rashba SOC is tunable and has a direct relationship with the crystalline phase transition and grain size by modifying halide-components, which leads to the halide-components dependent magneto-PL effects in 3D LHP thin films. This work paves the way for improving the luminescence property of opto-spintronics materials via modulating Rashba SOC.