Two-dimensional BiTeX crystals with persistent luminescence induced by photochemical reactions

Two-dimensional (2D) materials are highly valued for their unique properties and potential applications, as they can display exotic behaviors differing from those of their bulk forms. Research on elementary and binary solids has been making great progress recently, while synthesizing multi-component 2D materials experimentally remains a challenge, despite the possibility of greatly extending the number of members of the 2D realm. In this study, we synthesized ternary BiTeX (X = Cl, Br, I) nanosheets with high crystallinity through an electrochemical exfoliation method. Structural analysis confirmed the retention of bulk composition in these nanosheets. Interestingly, the BiTeX nanosheets display a persistent luminescence effect, where the photogenerated carriers exhibit lifetimes of over 100 seconds. Furthermore, the recovery time increased at lower temperatures. The persistent luminescence in 2D BiTeX, which can be ascribed to reversible bond cleavage and recovery under photoexcitation, exhibits potential for applications in fluorescence and photo-responsive systems.