Poly(arylene piperidine) Quaternary Ammonium Salts Promoting Stable Long‐Lived Room‐Temperature Phosphorescence in Aqueous Environment

Abstract Room‐temperature phosphorescence (RTP) materials have garnered considerable research attention owing to their excellent luminescence properties and potential application prospects in anti‐counterfeiting, information storage, and optoelectronics. However, several RTP systems are extremely sensitive to humidity, and consequently, the realization of long‐lived RTP in water remains a formidable challenge. Herein, a feasible and effective strategy is presented to achieve long‐lived polymeric RTP systems, even in an aqueous environment, through doping of synthesized polymeric phosphor PBHDB into a poly(methyl methacrylate) (PMMA) matrix. Compared to the precursor polymer PBN and organic molecule HDBP, a more rigid polymer microenvironment and electrostatic interaction are formed between the PMMA matrix and polymer PBHDB, which effectively reduce the nonradiative decay rate of triplet excitons and dramatically increase the phosphorescence intensity. Specifically, the phosphorescence lifetime of the PBHDB@PMMA film (1258.62 ms) is much longer than those of PBN@PMMA (674.20 ms) and HDBP@PMMA (1.06 ms). Most importantly, a bright‐green afterglow can be observed after soaking the PBHDB@PMMA film in water for more than a month. The excellent water resistance and reversible response properties endow these systems with promising potential for dynamic information encryption even in water.