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

Abstract 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.