Composition-dependent thermoelectric properties of hybrid tin perovskites (CH3NH3)xCs1−xSnI3: insights into electrical and thermal transport performance†

This work presents a comprehensive investigation of the thermoelectric properties of bulk hybrid perovskites with the general formula MA_xCs_1−xSnI₃ (0 ≤ x ≤ 1). A series of bulk samples were synthesized and systematically characterized to explore the relationship between composition, microstructure, and thermoelectric performance. Compositions with intermediate MA⁺ content (x = 0.2 and x = 0.5) show an optimal balance between electrical conductivity and Seebeck coefficient, yielding high power factor values (0.6–0.7 μW cm⁻¹ K⁻² at 423 K) and favorable thermoelectric performance with zT values up to 0.06. In contrast, compositions with MA⁺ contents (x = 0, x = 0.6, and x = 0.8) exhibit lower thermoelectric performance due to reduced Seebeck coefficients or suppressed conductivity. MASnI₃ shows promising low-temperature thermoelectric performance with a maximum zT of 0.10 at 423 K, attributed to its rapidly increasing Seebeck coefficient. These findings highlight the importance of microstructural control and composition optimization in the development of hybrid perovskites for thermoelectric applications.