Structural, electronic, optical, and thermoelectric properties of 2D honeycomb-like 1T-Rb2S monolayer: A DFT study

Abstract

The unique and alluring properties of 2D materials in contrast to the bulk counterparts have fascinated many researchers worldwide. They show excellent tunable properties due to the quantum confinement effect. In this study, ab initio simulations for the 1T-Rb2S monolayer have been performed based on the Density Functional Theory (DFT). DFT calculations are carried out by the PBE-GGA exchange-correlation functional via Wien2K software. On performing electronic and structural studies, the Rb2S monolayer shows an indirect band gap and is a semiconductor that has a bandgap value of about 1.64 eV. The dynamical and structural stability of the Rb2S monolayer is validated via phonon calculations. The optical properties were studied to determine the photovoltaic applications of the material in the nano regime. The optical properties of the Rb2S were carried out using the OPTIC package in Wien2k. The optical properties such as dielectric function (ε), absorption coefficient (α), Energy Loss (L), Reflectivity (R), and the refractive index (n), as a function of energy, have been computed. Rb2S monolayers display more prominent results in the ultra-violet region than the visible region ensuring that Rb2S monolayers are exceptional candidates for photovoltaic applications. The thermal properties of the 2D 1T-Rb2S have been computed by employing BoltzTraP interface, the thermoelectric analysis such as electrical conductivity, electronic thermal conductivity, Seebeck coefficient (S), the figure of merit (ZT) and the power factor (PF) has been computed and it rigidly ensures that the Rb2S monolayer is a potential candidate for thermoelectric device applications. The charge transfer mechanism is analysed by computing the mobility of charge carriers (ϑ), effective mass (meff) and relative ratio of the effective mass (D).