Centimeter‐Sized Single Crystals of Tetrahedral Manganese (II) Halide Hybrids for Wide‐Color Gamut Backlighting Displays

Phosphors with narrow‐band green emissions and high photoluminescent quantum efficiency (PLQY) are significantly required for backlighting displays with wider color gamut. In this work, two centimeter‐sized manganese (II) halide single crystals TMG 2 MnCl 4 and TMG 2 MnBr 4 (TMG = 1,1,3,3‐tetramethylguanidine) are synthesized, exhibiting bright narrow‐band green emissions with high PLQYs up to 62% and 90%, respectively. The narrow‐band green light emission is located at 520 nm with a full‐width at half‐maximum (FWHM) of only 57 nm. The photoluminescence mechanisms of two single crystals are elaborated. Two white‐light‐emitting diodes for backlighting displays (BD‐WLEDs) based on them are fabricated, exhibiting the widest color gamut of 122% National Television Standards Committee (NTSC), and a luminous efficacy reached ≈93 lm W −1 with excellent luminescence stability at high temperatures. These properties indicate the potential applications of tetrahedral manganese (II) hybrids in wide‐color gamut backlighting displays.