A thermally induced fluorescence enhancement strategy for efficient all-inorganic rubidium manganese halide

Abstract

Metal halides show great promise as next-generation emitting materials owing to their outstanding emission properties. However, achieving the application of white light-emitting diodes (WLEDs) based on lead-free metal halides is a challenge because of the lack of stable and efficient red emitters. In this study, we synthesized all-inorganic Rb₂MnBr₄·2H₂O crystals with isolated [MnBr₄O₂]H₄²⁻ octahedron units. By the thermo-induced partial dehydration process, the obtained Rb₂MnBr₄·0.9H₂O showed a broad red emission at 653 nm with high quantum efficiency up to 62.8%, which was ascribed to the suppressing of non-radiative recombination deriving from water molecules and the confinement excitons into polyhedron units. Moreover, Rb₂MnBr₄·0.9H₂O crystals exhibited good thermal stability, which still maintains 88% of room temperature emission intensity under 480 K. Owing to the excellent efficiency and stability of the red emitters, the as-fabricated WLED showed an excellent luminous efficacy of 84.84 lm W⁻¹ and a high color rendering index of 91.5 with a correlated color temperature of 5238 K. This work provides a new strategy to explore the red emission of metal halide materials for WLEDs.