Elastic-acoustic, optical and thermoelectric investigation of Cu6AsS5X (X= Br, I) for renewable energy applications

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First-principles computations examine the structure, optoelectronic, elastic-acoustic, and thermoelectric characteristics of Cu6AsS5X (X = Br, I). The renowned Perdew – Burke – Ernzerhoff generalized gradient approximation (PBEsol–GGA) was employed to compute the physical and elastic parameters; however, the energy band structure of Cu6AsS5Br and Cu6AsS5I has been more precisely determined by employing the Trans and Blaha technique of the modified Becke-Johnson (TB–mBJ) potential. The lattice constants of Cu6AsS5Br and Cu6AsS5I in the cubic structure increase from 10.24 Å to 10.27 Å as a consequence of an increase in atomic number (ionic size). Several properties are extracted from the computed density of state (DOS) and band structure (BS). The computed values for the gap between the valence and conduction bands indicate that the compounds are semiconducting. These compounds' prominent absorption peaks in the UV energy range suggest that argyrodites can be utilized for optoelectronic (OE) devices operating in this spectral region. The cubic compounds (C11, C12, and C44) elastics constants, as well as different parameters like Kleinman's parameters ζ, Hardness (H), melting temperature (Tm), Lame's constant, Zener anisotropy (A), acoustic behavior and its isotropy, and Poisson ratios (ʋ) are calculated. Furthermore, the thermoelectric properties have been calculated using the BoltzTrap package integrated into WIEN2K. The positive Seebeck coefficient (S), increased electrical conductivity (σ) and low thermal conductivity (k) indicates p-type semiconductors. These compounds' greater Figure of merit (ZT) shows their potential candidacy for thermoelectric applications