Near‐Unity Narrow Green Emitting in Manganese Halides Realized by Direct Precipitation Synthesis

Abstract In the realm of light‐emitting diode (LED) displays, the search for an ideal green emitter has been a challenge. The desired efficient emission band ≈520 nm has proved elusive, with the commercially available β‐Sialon falling short due to its longer wavelength and limited efficiency. Even the next‐generation micro‐LED displays are not immune to this issue, as β‐Sialon lacks the solution‐processable properties required for such applications. Here, a bright manganese halide narrow green emitter with higher efficiency and wider color gamut is discovered, possessing additional solution‐processable properties that make it a superior alternative to β‐Sialon. Synthesized through a direct precipitation method, the particle shape of benzyl trimethylammonium manganese bromide (BTA 2 MnBr 4 , BTA: C 10 H 16 N) is well controlled, unlocking its near‐unity efficiency. The LED fabricated by BTA 2 MnBr 4 showcases superior luminous efficiency compared to commercial β‐Sialon, while its color gamut reaches an impressive 110% National Televison System Committee (NTSC). Moreover, a good BTA 2 MnBr 4 film is successfully fabricated using the spin coating method, boasting a film thickness of 220 nm and a smooth surface with a roughness of 4.18 nm. This study presents a remarkable and eco‐friendly narrow green emitter that can potentially lead to more sustainable and energy‐efficient displays in the future.