Structural and Electrical Characterization of Cs2SnBr6: Insights From Raman Spectroscopy and Conductivity Under Varying Light Conditions

Abstract

Lead-free tin halide perovskites, particularly Cs₂SnBr₆, are gaining significant attention for their potential in optoelectronic applications. In this study, we investigate the material's electrical and vibrational properties under varying illumination conditions, providing novel insights into the impact of light on its conduction mechanisms. Cs₂SnBr₆ was synthesized via liquid-phase and solid-state reactions, and we report comprehensive analyses of its impedance, AC conductivity, and dielectric properties over a wide frequency range. Notably, our results reveal that light-induced photogenerated charge carriers enhance conductivity, which is well explained by the overlapping large-polaron tunneling (OLPT) model, while in darkness, the material follows the correlated barrier hopping (CBH) model. Moreover, Raman spectroscopy highlights structural changes, including a slight shortening of Sn–Br bond distances under illumination, which influences the vibrational frequencies and intensities. These findings emphasize the crucial role of illumination in tuning the electrical and dielectric responses of Cs₂SnBr₆, thus demonstrating its considerable promise for future optoelectronic applications, such as solar cells and photodetectors.