Electronic and optical properties modulation of heterostructures based on Na2S and h-BN under biaxial strain

Abstract

This research explores the structural, electronic, and optical characteristics of Na₂S monolayers and bilayers, as well as their heterostructures with h-BN, using first-principles calculations. The results reveal that the heterostructure of Na₂S monolayers and h-BN effectively modulates the bandgap while maintaining the intrinsic band structure trend of Na₂S. The introduction of heterostructures and misaligned stacking with h-BN leads to a blue shift in optical spectra, potentially eliminating visible light absorption under extreme conditions. Additionally, h-BN significantly stabilizes light absorption and reflection within the visible range, maintaining a consistent trend. Strain engineering further adjusts the sandwiched heterostructure's bandgap, achieving a total bandgap variation of ∼0.6 eV under −6 % to +6 % strain and exhibiting Type-I → II → I band alignment transitions. These findings offer insights for designing optoelectronic devices and provide theoretical guidance for applications like optical switches, integrated filters, and memristor substrates in different environments.