Investigation of X2GaAgCl6 (X = K, Cs) for Optoelectronic Devices: A Density Functional Theory Study

Abstract

The electronic, elastic, structural, and optical properties of X2GaAgCl6 (X = K, Cs) are investigated by using the full potential linearized augmented plane wave (FP‐LAPW) method based on density functional theory (DFT). Generalized‐gradient approximation (GGA) is used along modified Becke–Johnson (mBJ) exchange potential. K2GaAgCl6 and Cs2GaAgCl6 reveal the direct bandgap (E g) of 2.57 and 2.63 eV, respectively, at Γ symmetry points. The negative values of formation enthalpy (−1.694 for K2GaAgCl6 and −1.798 for Cs2GaAgCl6) and value of tolerance factor (τ) close to unity (0.82 for K2GaAgCl6 and 0.89 for Cs2GaAgCl6) confirm the stable nature of X2GaAgCl6 (X = Cs, K) compounds in cubic phase. Optical properties such as absorption coefficient α(ω), optical conductivity σ(ω), reflectivity R(ω), extinction coefficient k(ω), refractive index n(ω), and dielectric constants (ε 1 and ε 2) are calculated. The ε 2(ω) spectrum of Cs2GaAgCl6 and K2GaAgCl6 shows highest absorption peaks at 4.8 and 4.9 eV, respectively. The highest absorption is observed from Cs2GaAgCl6 at 7.44 eV and from K2GaAgCl6 at 7.46 eV energies. It is also noted that A2GaAgCl6 (A = K, Cs) compounds are elastically stable, anisotropic, and ductile. Investigation of elastic, structural, and optical properties shows that the compounds M2GaAgCl6 (M = Cs, K) can be potential candidates for optoelectronic applications.