Electronic and optical properties of ternary kagome Rb₂Ni₃S₄: a density functional study

Abstract

The application of semiconductors with optical properties has grown significantly in the development of semiconductor photovoltaics. Here, we explore the
electronic and optical properties of ternary transition metal sulfide Rb2Ni3S4 by means of density functional theory. From the structural perspective, Ni atoms is found to form a kagome-like lattice in a two-dimensional plane of Rb2Ni3S4. From our calculations, Rb2Ni3S4 is found to be a semiconductor with an indirect band gap of ∼0.67 eV. Strong hybridization was observed between the S-3p with the Ni-3dxz and Ni-3dyz orbitals. Interestingly, a flat band was noticed below the Fermi level demonstrating one significant feature of kagome lattice. From the optical calculations, Rb2Ni3S4 is found to exhibit optical activity in both the visible and lower ultraviolet regions of the incident photon energies. The optical response suggests this material may be a potential candidate for opto-electronic device, given its ability to interact with light across a broad range of wavelengths. This work is expected to motivate the experimental group for transport measurements and may provide a new foundation in optics.