Document Type : Research

Authors

• Asma Moradi ¹
• Ali Mokhtari ²

¹ PhD student in solid state physics of Shahrekord University

² Associate Professor, Departement of Physic, Faculty of Science, Shahrekord University, Shahrekord, Iran

Abstract

A B S T R A C T
In the present work, the structural, electronic and optical properties of the lead-free double perovskites Cs2AgBiX6 (X=Br or Cl) are analyzed in the framework of density functional theory (DFT) using the local density and generalized gradient approximations (LDA and GGA) by the Abinit computational package. These compounds are good alternative to lead halide perovskites due to their good stability and non-toxicity. The optical excitations of the double perovskites are important due to their optimal band gap in the visible light spectrum and low excitonic binding energy. The optical properties including: absorption, refraction, extinction and reflection coefficients and loss function are obtained using random phase approximation in the Kohn-Sham (RPA-KS) and Green (RPA-GW) approaches. The results of the Green's function approach are in better agreement with the results of experimental works respect to the RPA-KS approach. In the visible region, there are not volume plasmons and the amount of energy loss is low.

Keywords

• "Double Perovskite"
• "Solar Cell"
• "Density Functional Theory"
• "Optical Properties"
• "Green's Function"