Dimension-Dependent Photoinduced Oxygen Passivation in Tin-Based Perovskites

Abstract

All-inorganic lead-free tin-based perovskites are ideal candidate materials for lead-based perovskites due to their environmentally friendly nature. However, their atmospheric instability remains a significant hurdle for practical applications. In this study, zero-dimensional (0D) Cs4SnBr6 and three-dimensional (3D) CsSnBr3 are synthesized via a one-step reaction method. 3D CsSnBr3 exposed to air exhibits significant photoluminescence (PL) enhancement after light soaking, a phenomenon that persists even after the light is removed, whereas 3D CsSnBr3 under a nitrogen atmosphere and 0D Cs4SnBr6 in air show no such effect. The PL enhancement is attributed to a dimension-dependent photoinduced oxygen passivation mechanism. The continuous network of [SnBr6]4– octahedra in 3D CsSnBr3 provides channels for oxygen diffusion, allowing subsequent reaction with defects and effectively suppressing nonradiative recombination channels. The isolated [SnBr6]4– octahedral structure in 0D Cs4SnBr6 restricts this process, indicating that 0D Cs4SnBr6 has better stability than 3D CsSnBr3. Therefore, the marked difference in passivation behavior directly originates from distinct structural dimensionalities and reflects their divergent environmental stability. This work clarifies the critical role of dimensional engineering in regulating perovskite–environment interactions. It offers new insights into designing high-performance and stable lead-free perovskite devices.