Insights on structural, elastic, electronic and optical properties of double-perovskite halides Rb2CuBiX6 (X=Br, Cl).

In this paper, the structural, elastic, electronic and optical properties of double-perovskite halides Rb 2 CuBiX 6 are studied using first-principles calculations based on density functional theory. The results show that Rb 2 CuBiX 6 (X = Br, Cl) have thermodynamic and mechanical stability according to the tolerance factor, binding energy, formation energy and Born-Huang stability criterion. The B/G value and Poisson's ratio indicate that Rb 2 CuBiX 6 is a flexible material. Rb 2 CuBiBr 6 and Rb 2 CuBiCl 6 are indirect bandgap semiconductors with bandgap values of 1.11 eV and 1.43 eV, respectively. In addition, the effective masses of electrons of Rb 2 CuBiX 6 are much smaller than that of other perovskite compounds, indicating that they have better carrier mobility. In the visible light range, Rb 2 CuBiX 6 has good dielectric properties and excellent light absorption properties. Therefore, Rb 2 CuBiX 6 has great potential in photovoltaic application due to their suitable bandgap values and excellent optical properties. • The bandgap values of Rb 2 CuBiX 6 (X = Br, Cl) are very suitable for photosensitive materials of solar cells. • The Rb 2 CuBiX 6 can be a potential candidate for excellent light absorbing material. • Rb 2 CuBiX 6 is the structural and thermodynamic stabilities. [ABSTRACT FROM AUTHOR]