Hydrochloric Acid-Assisted Synthesis of Red Emissive Hybrid Mn2+ Halides for Wide Gamut Displays

Lead-free red emissive hybrid Mn2+-based metal halides have emerged as promising phosphors for lighting and display applications owing to their environmental friendliness and d-d transition. However, simultaneously enhancing emission efficiency and narrowing the red-emission bandwidth of Mn2+ halide phosphors remains challenging. Here, we report an HCl-assisted precipitation strategy for synthesizing (CH3)4NMnCl3 phosphors. The introduction of HCl creates an acidic and chloride-rich chemical environment, thereby improving crystallization and luminescence emission efficiency. The as-prepared (CH3)4NMnCl3 phosphors exhibit a red emission at 629 nm with a photoluminescence quantum yield of 70.77% and a narrow full width at half-maximum of 75.16 nm. The phosphors have good thermal stability (retained 80.77% of initial PL intensity at 423 K) and thermal-cycling stability. The as-fabricated light-emitting diodes (LEDs) using (CH3)4NMnCl3 as red emitters exhibit excellent operational stability, with 98.29% of initial luminous efficiency (LE) being maintained after 224 h of continuous operation. In addition, the assembled white LED delivers an LE of 88.41 lm/W and achieves a wide gamut covering 101.7% of the NTSC 1931. These results provide an effective strategy for achieving efficient and narrow-band hybrid Mn2+ halide phosphors, offering a promising lead-free emitter for wide-gamut display applications.