Highly Thermostable Hybrid Manganese Bromide as a Narrow-Band Green Phosphor for Backlight Displays

Zero-dimensional manganese-based halides are distinguished by their advantages, such as high luminescence efficiency, tunable spectra, and straightforward preparation. However, the challenge of synergistically enhancing their luminescence and thermal stability remains a critical issue. Here, we synthesized a novel Mn(II)-based metal halide of (Meop)2MnBr4 (Meop = 1-(2-methoxyphenyl)piperazine). Characterized by a distinct d-d transition of Mn2+, this material demonstrates a narrow-band green emission centered at 521 nm. It emits with a full width at half-maximum of merely 41 nm and achieves a near-unity photoluminescence quantum yield (99%). In addition, the color purity of (Meop)2MnBr4 was calculated to be 71.09%, which is higher than the 53.21% of the commercial phosphor β-sialon:Eu2+. Benefiting from its structure, (Meop)2MnBr4 demonstrates outstanding thermal stability, with its photoluminescence intensity at 430 K remaining 93% of the original value at 305 K. Based on the above advantages, we fabricated a white LED device using the (Meop)2MnBr4 powders. The WLED yields a luminous efficacy of 90.35 lm·W-1 alongside a broad NTSC color gamut coverage of 105.7%. This work not only provides new light on the synthesis of high-performance luminescent materials but also paves the way for their practical deployment.