High Quantum Efficiency Zn2+ Doped Lead Manganese Halide @PET Film Used for Wide Color Gamut Backlit Display

Abstract Organic–inorganic manganese halide with environmentally friendly properties has become a new candidate material for backlight display applications. In this article, tetraethylammonium bromide (C 8 H 20 N) 2 MnBr 4 is synthesized by a simple room temperature evaporation method. The tetrahedral coordinated Mn 2+ demonstrates a green emission peak at 523 nm and a commendable photoluminescence quantum yield (PLQY) of 81.7%. To improve its stability, different proportions of Zn 2+ are incorporated, leading to the discovery of (C 8 H 20 N) 2 Mn 0.95 Zn 0.05 Br 4 as the most stable variant with a high PLQY of 84.3%. Additionally, by utilizing a sandwich method and double‐layer polyethylene terephthalate (PET) film encapsulation, the powder‐to‐binder ratio and thickness gradient are optimized, resulting in the ideal (C 8 H 20 N) 2 Mn 0.95 Zn 0.05 Br 4 @PET film with a powder‐to‐binder ratio of 1:2 and a thickness of 0.5 mm. Remarkably, the film exhibits superior stability against water, heat, and photo degradation. Finally, the light conversion film prepared from (C 8 H 20 N) 2 Mn 0.95 Zn 0.05 Br 4 @K 2 SiF 6 : Mn 4+ @PET composite material is applied to backlight display, and the color gamut covers 112% of NTSC 1953 and 83% of Rec. 2020. This study provides a feasible route for developing environmentally friendly, low‐cost, and high‐performance liquid crystal displays.