Exploring Chalcohalide Perovskite-Inspired Materials (Sn 2 SbX 2 I 3 ; X = S or Se) for Optoelectronic and Spintronic Applications.

Chalcohalide perovskite-inspired materials have attracted attention as promising optoelectronic materials due to their small band gaps, high defect tolerance, nontoxicity, and stability. However, a detailed analysis of their electronic structure and excited-state properties is lacking. Here, using state-of-the-art density functional theory, an effective k · p model analysis, and many-body perturbation theory (within the framework of GW and BSE), we explore the band splitting and excitonic properties of Sn 2 SbX 2 I 3 (X = S or Se). Our findings reveal that the Cmc 2 1 phase exhibits Rashba and Dresselhaus effects, causing significant band splitting, especially near the conduction and valence band extremes, respectively. Moreover, we find that the exciton binding energy is larger than those of lead halide perovskites but smaller than those of chalcogenide perovskites. We also investigate polaron-facilitated charge carrier mobility, which is found to be similar to that of lead halide perovskites and greater than that of chalcogenide perovskites. These characteristics make these materials promising for applications in spintronics and optoelectronics.