Intriguing optoelectronic and visible-light activated photocatalytic properties of 2D AlN/GaN and TMDCs (MX2; M = Mo/W, X = S/Se) monolayers and their bilayer vdWs heterostructures

Abstract

First-principles calculations reveal that 2D Group III–V binary compounds (AlN/GaN) and TMDCs (MX₂; M = Mo/W and X = S/Se) exhibit stable novel bilayer van der Waals (vdWs) heterostructures, with the AA-stacking pattern being the most stable. These direct band gap semiconductors have energies ranging from 1.45 to 2.96 eV, and their band gap nature enhances charge carrier mobility, which is beneficial for nanoelectronics. The p-orbital of AlN/GaN and d-orbital of TMDCs primarily contribute to the formation of conduction and valence bands, respectively. All vdWs heterobilayers show a type-II band alignment, ideal for light harvesting and detection. Bader population analysis confirms interlayer charge transfer, and the materials demonstrate strong light absorption, which is attributed to their robust quantum and dielectric confinement. MoS₂ and MoSe₂ notably exhibit a blue shift in their absorption spectra. Furthermore, these heterobilayers have promising photocatalytic properties for water dissociation, with band edge potentials computed for a pH range from 0 to 7, showing changes in the conduction and valence bands with varying pH levels.

Graphical abstract