Synergistic effect of Bi3+ and extrinsic self-trapped excitons towards effective polychromatic luminescence in layered Sr3Sc2O5Cl2

Developing efficient yellow-green phosphors with tunable photoluminescence properties is pivotal for enhancing both the color rendering index of near-ultraviolet pumped white LEDs and the anti-counterfeiting efficacy through dynamic chromatic encryption. In this study, a layered Ruddlesden-Popper oxychloride Sr 3 Sc 2 O 5 Cl 2 doped with Bi 3+ is prepared by high-temperature solid-state method, exhibiting a broadband emission centered at 510 nm with a high internal quantum efficiency of 90.5 %. Structural and spectroscopic analyses reveal that the yellow-green luminescence originates from the superposition of self-activated emission induced by extrinsic self-trapped excitons and interconfigurational s-p transition of Bi³ ⁺ ions. In view of the distinct excitation responses of different emission centers, excitation-wavelength modulation enables continuous emission color tuning from cyan to orange-yellow in a single-phase phosphor. The successful demonstration of high-color-rendering white light ( R a = 96) and multi-level optical encryption validates the significant application potential of Sr 3 Sc 2 O 5 Cl 2 series phosphors in next-generation near-ultraviolet pumped white LEDs and high-security anti-counterfeiting/encryption systems.