Computational prediction and characterization of single-layer CrS ₂

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.