The electronic and optical properties of monolayer Y2A2BB′ (A = S, Se, or Te, B, B′ = I, Br, Cl, or F; B ≠ B′) by first-principal calculation

Monolayer Y₂Se₂BB′ (B, B′ = I, Br, Cl, or F; B ≠ B′) has attracted significant attention as a promising optoelectronic material for photodetection and photocatalysis. However, other elements in the same family as Se, such as S and Te, which share similar chemical properties, have been less explored. In this study, we systematically investigated the electronic and optical properties of monolayer Y₂A₂BB′ (A = S, Se, or Te; B, B′ = I, Br, Cl, or F; B ≠ B′), and the trends of various properties under biaxial strain. The band gap of Y₂A₂BB′ varies is near the visible light spectrum, indicating its potential for application in the visible light region. All Y₂A₂BB′ compounds exhibit a high absorption coefficient in the ultraviolet range, while Y₂Te₂BB′ shows excellent performance in the visible light region, with an absorption coefficient reaching 3 × 10⁵ cm⁻¹. By applying strains, we achieved a broad absorption range and successfully enabled Y₂Te₂BrCl to span the redox potential of water, facilitating efficient water decomposition. Our calculations provide valuable insights into the properties of Y₂A₂BB′, supporting their potential use in optoelectronic devices.