Computational prediction and characterization of single-layer CrS₂

Abstract

Using first-principles calculations, we predict a previously unreported bulk CrS2 phase that is stable against competing phases and a low energy dynamically stable single-layer CrS2 phase. We characterize the electronic, optical, and piezoelectric properties of this single-layer material. Like single-layer MoS2, CrS2 has a direct bandgap and valley polarization. The optical bandgap of CrS2 is 1.3 eV, close to the ideal bandgap of 1.4 eV for photovoltaic applications. Applying compressive strain increases the bandgap and optical absorbance, transforming it into a promising photocatalyst for solar water splitting. Finally, we show that single-layer CrS2 possesses superior piezoelectric properties to single-layer MoS2.