Monolayers Sn2Te2X4 (X = P, As) as promising materials for photocatalytic water splitting and flexible devices: a DFT study

Abstract

First principles calculation was performed to study the Sn₂Te₂X₄ (X = P, As) monolayers. Structural investigation confirms the stability of the two monolayers with Young's modulus in the range of 30.34–33.65 N m⁻¹ and a Poisson's ratio of 0.18–0.21. The two monolayers are semiconductors with a direct band gap of 1.52–1.66 eV. The light absorption rate of the two monolayers is rather high 10⁴–10⁵ cm⁻¹. Both monolayers have high charge carrier mobility and suitable VBM and CBM positions for the redox reaction. The η_STH efficiency of both materials (15.76–17.12%) is close to the theoretical limit of 18%. Moreover, moderate strains can improve the light absorption rate, while the suitable VBM and CBM positions are preserved. These characteristics suggest that Sn₂Te₂X₄ (X = P, As) monolayers are good candidates for being applied in flexible devices and for the conversion of solar energy to other types of energy.