Thickness-induced band-gap engineering in lead-free double perovskite Cs2AgBiBr6 for highly efficient photocatalysis

摘要: In recent years, two-dimensional (2D) lead-free double perovskites have been attracting much attention because of their unique performance in photovoltaic solar cells and photocatalysis. Nonetheless, how thickness affects the photoelectric properties perovskite remains unclear. this work, by means density functional theory (DFT) with a spin orbit coupling (SOC) effect, we investigated electronic optical systemically, including band structures, carrier mobility, absorption spectra, exciton-binding energies, edges alignment molecule adsorption Cs2AgBiBr6 different thicknesses. The calculated results revealed thickness-induced gap for Cs2AgBiBr6. It shows low outstanding visible ultraviolet light. When is reduced to monolayer, moves from an indirect direct gap. Moreover, mobility excellent energy increases decreased thickness. Importantly, analysis edge indicates that prone H2O H2 desorption theoretically, which conducive photocatalytic water splitting hydrogen generation other photovatalytic reactions. Our work suggests potential candidate as cell or photocatalyst, provide theoretical explorations into reducing layers materials 2D atomic better application, can serve guidelines design photocatalysts.