Two-Dimensional Tin-Based Chiral Perovskites with a High Degree of Circularly Polarized Luminescence

Two-dimensional (2D) hybrid organic–inorganic halide perovskites have garnered increasing attention due to their unique physical properties and potential applications in optoelectronic devices. Introducing chiral organic ligands into layered inorganic frameworks can impart strong chirality to pure 2D perovskites, offering the potential for applications in circularly polarized light emission and detection. However, most of them are lead-based chiral perovskites, which inherit the toxicity of lead. To overcome the toxicity limitations, lead-free chiral perovskites have been developed by using manganese (Mn), copper (Cu), bismuth (Bi), and tin (Sn). Among these alternatives, tin (Sn) has emerged as the most promising candidate because tin and lead both have similar ionic radii and valence electron structures. Nevertheless, the study of 2D tin-based chiral perovskite is still in fancy. Here, we report a new two-dimensional tin-based chiral perovskite (S-/R-3BrMBA)2SnI4 [3BrMBA = 1-(3-bromphenyl)-ethylamine] with a high degree of circularly polarized light emission. The as-synthesized 2D tin-based chiral perovskite (S-3BrMBA)2SnI4 shows an average (maximum) degree of circular polarization (DOCP) of 26.2% (35.8%) at 78 K, which is the highest value in lead-free chiral perovskites reported to date and might be ascribed to the large lattice distortion induced by the chiral ligands. The DOCP decreases with increasing temperature and maintains a constant value with the excitation power. The high DOCP in our pure chiral 2D perovskites would shed light on the development and exploration of lead-free spin-associated optoelectronic devices.