First principle investigation of essential physical properties of stable Lead-free double perovskites Cs2AgAuX6 (X = cl, Br) for green energy applications

Abstract

In this research, we have utilized density functional theory (DFT) simulations using the full potential linear augmented plane-wave (FPLAPW) approach to estimate the properties of double perovskites. We utilized the PBE-GGA, to calculate structural properties. To calculate the optical and electronic properties of our understudy compounds, we have used the modified Becke and Johnson (mBJ) potential functional. Our findings reveal that these perovskites exhibit band gaps of 1.24 eV and 0.54 eV for X = Br and Cl, respectively. The optical characteristics have been studied using dielectric constants, absorption, refractive index, and reflectivity, which suggest that these double perovskites could be used in solar cells, with the highest transition values in the visible region of photon energy. Furthermore, our transport property calculations using the Boltzmann transport equation indicate that our understudy compounds are best for thermoelectric applications. This research aims to explore and open new doors to experimental and theoretical scientists in the field of optoelectronic and thermoelectric devices.