The bandgap engineering of double perovskites Cs2CuSbX6 (X = Cl, Br, I) for solar cell and thermoelectric applications

Over recent years, the research on lead-free halide double perovskites (DPs)-based materials has credited attention because of their promising applications in solar cells and renewable energy. Herein, we tried to computationally analyze the optoelectronic as well as the thermoelectric characteristics of a unique compound Cs2CuSbX6 (X = Cl, Br, I) by density functional theory (DFT). The calculation of tolerance factor (tF), lattice constant (ao), and formation enthalpy (Delta Hf) show that the investigated DPs are stable both structurally and thermodynamically. The value of bandgaps of Cs2CuSbX6 (X = Cl, Br, I) explicates indirect bandgaps with values 1.04, 0.75, and 0.46 eV for Cs2CuSbCl6, Cs2CuSbBr6, and Cs2CuSbI6, respectively. Further, maximum optical absorption between energy range 1.0 to 3.0 eV has proved that studied DPs are potential candidates for solar cells and infrared detectors. By exploiting the semi-classical Boltzmann theory, the calculated figure of merit (ZT) verifies the optimal value for electrical conductivity and the respective Seebeck coefficient for the studied compounds. Interestingly, the compound Cs2CuSbCl6 has the highest ZT among studied DPs. The present study provides a theoretical base for the studied DPs which is necessary to understand and compare future experi-mental investigations to seek diverse optoelectronic and thermoelectric applications.

Automated summary

In this study, the optoelectronic and thermoelectric properties of Cs2CuSbX6 (X=Cl, Br, I) were analyzed computationally using density functional theory. The results indicate that these double perovskite materials are structurally and thermodynamically stable, with indirect bandgaps suitable for solar cells and infrared detectors.