First principles insights into Cs2XAgCl6 (X= Sc, Y) compounds for energy harvesting applications

Abstract

Herein, the investigation is presented to analyze the structural, electronic, optical, and thermoelectric features of Cs2XAgCl6 (X= Sc, Y) by applying the first principles approach. The confirmation of the stable structure of both compounds is reinforced by the negative values of formation enthalpies. The electronic band gaps (Eg) of 3.78/4.86 eV are computed for Cs2ScAgCl6 /Cs2YAgCl6 through Tran-Blaha modified Becke-Johnson (TBmBJ) potential, correspondingly. The tolerance factor(τ) is found as 0.9 for Cs2ScAgCl6 and 1.0 for Cs2YAgCl6 which confirmed the stable cubic nature of both compounds. Optical factors like dielectric-function ε(ω), absorption coefficient α(ω), and others related parameters are analyzed within 0 to 10 eV of energy span. Both compounds demonstrated high absorption in the ultraviolet region, rendering them as well-suited materials for photovoltaic applications. The calculated values of refractive index for Cs2ScAgCl6 and Cs2YAgCl6 indicated super-luminescent characteristics in the ultraviolet region. For thermoelectric (TE) features, electrical conductivity (σ/τ), figure of merit (ZT), power factor (PF), thermal conductivity (k/τ), and Seebeck coefficient (S) are calculated using the BoltzTraP code. According to the findings, both materials are advocated as promising candidates for thermoelectric and optoelectronic applications.