CsSnBr₃ and Cs₃Bi₂Br₉: Structural, Optical Characteristics, and Application in a Schottky Barrier Diode

Abstract

The search for alternatives to Pb‐based perovskites, due to concerns about stability and toxicity, has led to the exploration of Pb‐free options. Tin (Sn) and bismuth (Bi) are promising candidates, given their similar ionic radii to Pb and the isoelectronic nature of Pb 2+ and Bi 3+ , which suggest comparable chemical properties. Among these, CsSnBr 3 and Cs 3 Bi 2 Br 9 are relatively underexplored but offer lower toxicity and enhanced stability while demonstrating optoelectronic properties suitable for various applications. In this study, CsSnBr 3 and Cs 3 Bi 2 Br 9 nanocrystals are synthesized using a colloidal method and integrated into Schottky diodes. X‐ray photoelectron spectroscopy analysis of the surface chemistry confirms improved thermal and phase stability compared to Pb‐based perovskites. Schottky diode parameters, including ideality factor, barrier height, and series resistance are assessed using conventional thermionic emission, modified Cheung's, and Norde's models. The Cs 3 Bi 2 Br 9 ‐based Schottky diode exhibits superior electrical performance with the lowest series resistance and optimal barrier height. Electrical impedance spectroscopy results indicated that CsSnBr 3 has higher resistances and lower capacitances than Cs 3 Bi 2 Br 9 , reflecting lower charge carrier mobility and more defects, although the R 1 C 1 regions in both materials demonstrated faster charge dynamics, making them ideal for high‐speed applications.