Two-dimensional YOBiS2 with narrow bandgap and high carrier mobility for infrared photodetector

Abstract

Two-dimensional (2D) materials are highly valued for their atomic-scale thickness and exceptional mechanical, optical, and electronic properties. However, most 2D materials have band gaps above 1.6 eV, limiting their applications in infrared detection. In this work, we predict a novel 2D semiconductor YOBiS2, using first-principles calculations. Analyses of formation energy, molecular dynamics, phonon dispersion, and mechanical stability confirm its structural and dynamical stability. Remarkably, using the GW approximation taking into account the SOC, 2D YOBiS2 exhibits a direct electronic band gap of 1.38 eV Calculations incorporating BSE indicate an exciton binding energy of 0.81 eV. Additionally, it has a low hole effective mass of 0.09 m0 and a high hole mobility of 1.66 × 104 cm2·V−1·s−1. 2D YOBiS2 possesses an exceptionally broad optical absorption spectrum, spanning from the near-infrared to the ultraviolet region, with an ultra-high absorption coefficient of 5.5 × 105 cm−1, highlighting its potential for high-performance infrared photodetectors.