Investigations of the structural, mechanical and optoelectronic attributes of Rb2BB'Tl I6 ( B'= As, Ga) double perovskites for photovoltaics

Abstract Double perovskites based on rubidium have demonstrated potential for obtaining high solar cell power conversion efficiencies. Their distinct crystal structure and electrical characteristics influence these materials' potential as effective light absorbers. In this present manuscript, a detailed scrutiny of the physical aspects of halide perovskites Rb2TlAsI6 and Rb2TlGaI6 is presented using density functional theory framework implanted in Wien2K code using. Modified Becke Johnson potential is employed to treat the exchange-correlation effects. A computed tolerance factor, octahedral tilting, and formation energy ensure the structural and thermodynamic stability of given structures. Three independent elastic constants and mechanical properties were computed using the Thomas Charpin method. Ductile nature of Rb2TlAsI6 and brittle nature for Rb2TlGaI6 is revealed from computed mechanical attributes. Electronic properties revealed a direct bandgap (1.09 eV) for Rb2TlAsI6 and an indirect bandgap (1.2 eV) for Rb2TlGaI6. Optical properties indicate high polarization and absorption of incident light, which is suitable for photovoltaic applications in the visible spectrum.