A comprehensive first-principles study exploring the structural, electronic, optical, transport, and photovoltaic properties of Rb2LiGa (Br/I)6 utilizing DFT and SCAPS-1D simulations

Abstract

Lead-free double perovskite halides are attracting substantial attention in optoelectronics due to their outstanding electronic, optical, and transport properties. These materials are not only stable and easy to synthesize but also present a wide range of potential applications. In this study, we explore the intriguing properties of Rb₂LiGa(Br/I)₆, emphasizing their structural, electronic, optical, transport, and photovoltaic characteristics. Our simulation results show that Rb₂LiGaBr₆ and Rb₂LiGaI₆ possess band gaps of 1.19 eV and 1.13 eV, respectively, highlighting their potential for various applications. Both compounds show remarkable optical performance, with high absorption coefficients and optical conductivity, along with low reflectivity across the UV-visible spectrum, making them excellent candidates for solar cell technologies. Furthermore, Rb₂LiGa(Br/I)₆ exhibit exceptional thermoelectric performance, with high figure-of-merit (ZT) values ranging from 200K to 800K, emphasizing their potential as efficient thermoelectric materials. Therefore, this study will provide guidelines for constructing efficient solar cells based on double perovskites. Motivated by the higher absorption coefficient and optical conductivity of Rb₂LiGa(Br/I)₆, we have modeled an Au/Cu₂O/Rb₂LiGa(Br/I)₆/TiO₂/FTO solar cell. We have observed that Au/Cu₂O/Rb₂LiGaI₆/TiO₂/FTO has higher efficiency than Au/Cu₂O/Rb₂LiGaBr₆/TiO₂/FTO. Additionally, the efficiency of Au/Cu₂O/Rb₂LiGaI₆/TiO₂/FTO is higher than that reported previously. Thus, this study provides guidelines for constructing efficient solar cells based on double perovskites.