Enabling Aqueous Phase Long‐lived Deep‐blue Phosphorescence With Layered Double Hydroxide

Aqueous-phase phosphors are of utmost importance for a myriad of applications. However, the emission wavelengths of the current aqueous organic room-temperature phosphorescent (RTP) materials are limited to green and red bands, while the blue part is rarely reported, thus limiting the development of a full-color RTP system. Theoretically, carboxylated benzene is expected to be blue phosphorescence-emissive, but only green phosphorescence is observed in solid, due to the strong intermolecular π-π stacking that decreases the energy gap. Herein, the use of water-dispersible layered double hydroxide (ZnAl-LDH) is proposed for isolating Ph-(COOH)_n and the distance between the adjacent chromophores is confirmed to be larger (≈7.0 Å) than the threshold of π-π interaction. Deep-blue phosphorescence with a lifetime over 0.1 s, and a maximum luminescence quantum yield of 42%, is harvested in the aqueous phase. The long-lived deep-blue phosphorescence is successfully explored for high-temperature display and luminescent dyes.