ACS Appl. Electron. Mater. 2022, 4, 4068−4076.https://doi.org/10.1021/acsaelm.2c00705

Phosphors with narrow-band emission are in great demand for liquid crystal display backlighting applications. In this work, four zero-dimensional Mn²⁺-based organic–inorganic metal halides (OIMHs), (C₁₃H₂₆N)₃MnBr₄·Br, (C₁₃H₂₆N)₂MnCl₄, and (C₇H₁₈N)₂MnX₄ (X = Cl, Br), were synthesized, and their crystal structures were solved. Under blue-light excitation, all of the materials exhibited bright narrow-band green luminescence centered at 515–525 nm with high photoluminescence quantum yields (PLQYs). Significantly, (C₁₃H₂₆N)₃MnBr₄·Br and (C₁₃H₂₆N)₂MnCl₄ exhibited small full width at half-maximum (FWHM) values of 43 and 48 nm with PLQYs of 77.8 and 79.3% at room temperature, respectively. Compared with the reported luminescent OIMHs, ultrahigh thermal quenching temperatures were observed, and at 420 K, emission intensities of (C₁₃H₂₆N)₃MnBr₄·Br and (C₁₃H₂₆N)₂MnCl₄, remained 82.7 and 64.2% of those at room temperature, respectively. The rigid environment provided by the C₁₃H₂₆N⁺ cation has a strong confinement effect on the [MnX₄]^2– tetrahedra, leading to a narrower FWHM and higher thermal quenching temperature. Finally, (C₁₃H₂₆N)₃MnBr₄·Br was combined with commercial phosphors to fabricate light-emitting diodes (LEDs) with a wide color gamut of up to 113% NTSC (National Television System Committee). This work provides a reference for designing the OIMHs for liquid crystal display LEDs by tuning the organic cations.