Coordination‐Locked Engineering to Achieve Narrowband Room Temperature Phosphorescence in Non‐Rare Earth Metal–Organic Frameworks

Abstract Non‐rare earth (RE) narrowband phosphorescent metal–organic frameworks (MOFs) remain a great challenge due to spectral broadening from overlapping emissions in complex coordination systems. Here, the first non‐RE narrowband room temperature phosphorescent (RTP) MOF crystal, Sr–tbc , constructed via coordination‐locked phosphorescence amplification ( CLPA ) of a tailored phosphor, 1‐(4‐carboxyphenyl)‐1H‐1,2,4‐triazole‐3‐carboxylic acid (H ₂ tbc), is presented. Sr–tbc , with 1D coordination chains, exhibits a significant narrowband RTP emission over a wide excitation wavelength range of 280–360 nm with a minimum half‐height full width value of 28.5 nm. This exceptional narrowband emission is attributed to the targeted coordination between triazolinic acid and Sr ions. This special coordination structure selectively enhances specific RTP emission and restricts vibrational dissipation through rigid molecular stacking. Furthermore, Sr–tbc shows potential in high‐resolution afterglow displays and multilevel information encryption. This work reports the first case of non‐RE narrowband phosphorescent MOF crystals and establishes a novel CLPA strategy for efficient RTP materials.