Cs2CuLuY6 (Y = Br, I) double halide perovskites: structural, optoelectronic, thermoelectric and thermo-mechanical insights for sustainable technologies

Abstract

This research provides an in-depth thorough assessment of the physical characteristics of Cs₂CuLuY₆ (Y = Br, I) materials using DFT. Structural stability is confirmed through tolerance factors, octahedral factors, and formation energy calculations, while elastic constants satisfy the Born stability criteria, indicating mechanical robustness. Phonon dispersion analysis reveals the absence of imaginary frequencies, confirming the dynamical stability of the investigated compounds. The evaluated Pugh's and Poisson's ratios suggest ductile behavior with noticeable elastic anisotropy. Electronic band structure analysis with GGA-PBE, TB-mBJ, and YS-PBE0 reveals that all investigated compounds are semiconductors with indirect band gaps. Optical analysis demonstrates strong absorption in the visible to UV region, highlighting their potential for optoelectronic and photovoltaic applications. Furthermore, thermoelectric analysis indicates promising thermoelectric performance with favorable figure-of-merit (ZT ∼ 1.0) values over a wide temperature range, highlighting their potential for both low-temperature cooling and high-temperature heat recovery. These findings point to Cs₂CuLuY₆ alloy as a versatile potential material for renewable energy applications, predominantly in solar cell and thermoelectric applications.