Pure organic room‐temperature phosphorescence (RTP) materials have attracted wide attention for their easy preparation, low toxicity, and applications in various fields like bioimaging and anti‐counterfeiting. Developing phosphorescent systems with more universality and less difficulty in synthesis has long been the pursuit of materials scientists. By employing a polymeric quaternary ammonium salt with an ionic bonding matrix and heavy atoms, commercial fluorescent dyes are directly endowed with phosphorescence emission. In a single amorphous polymer, the external heavy‐atom effect generates excited triplet states and the rigid polymer matrix stabilizes them. This study put forward a new general strategy to design and develop pure organic RTP materials starting from existing library of organic dyes without complicated chemical synthesis.

Growing attention has been paid to pure organic room-temperature phosphorescence (RTP). Although an insufficient population and fast nonradiative decay of triplet excitons are avoided in recent endeavors, complicated synthesis and limited universality still hinder its development. Further, fluid RTP materials are more difficult to design because of faster nonradiative relaxation. Herein, a deep eutectic mixture of glucose and choline, a stable supercooled liquid at room temperature, is employed as a matrix. Direct transformation from commercial fluorescent dyes to RTP fluid is realized by doping without modifications. The excited triplet states are generated by an external heavy atom, while the rigid noncovalent network stabilizes them with both functions intrinsic to the liquid matrix. Modulation of matrix components also results in nearly white light emission of a single dye. This study presents a general strategy to design fluid RTP materials starting from the vast library of fluorophores.

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It is known that without noble metal, the spin flip between singlet states and triplet states is generally a forbidden process and that the long-lived triplet excitons of pure organic luminogens tend to undergo nonradiative decays including thermal motions, collision and exposure to quenchers such as oxygen. [6] Therefore, phosphorescence from metal-free materials is normally observed at low temperature (e.g., 77 K) and under inert conditions (e.g., protection by argon gas). [7] Tang and co-workers proposed crystallization-induced phosphorescence (CIP) mechanism, through which efficient RTP materials can be constructed. [8] Still, crystalline RTP materials require strict growth conditions, which might restrict their processability in applications.To overcome these shortcomings, several metal-free amorphous RTP materials have been reported. Methods of embedding pure organic phosphors into rigid polymer matrices, macro cycle hosts, or supramolecular hosts either covalently linked or noncovalently adsorbed are commonly used to inhibit nonradiative decay and enhance RTP emissions. [9] Amide phosphorescent polymers are frequently reported due to the rigid environment provided by both polymer matrices and hydrogen bonds. Our group has prepared several acrylamide copolymers, which are typical examples. [10] Nevertheless, the pure organic amorphous polymeric systems with effective RTP emission are still rare. Till now, amide copolymers with lactam structures bringing out RTP have rarely been reported, while poly(N-vinylpyrrolidone) (PVP) and poly(N-vinylcaprolactam) (PNVCL) are good candidates with facile preparations and wide availability of monomers.In this work shown in Scheme 1, a design strategy was presented for pure organic phosphorescent polymers (PVP-BrNpA, PVP-BA, PVP-BrHexene, PNVCL-BrNpA, PNVCL-BA and PNVCL-BrHexene) by copolymerizing lactam monomers, namely, N-vinylpyrrolidone (NVP) and N-vinylcaprolactam (NVCL) with small amounts of other monomers, benzonic acid (BA), bromonaphthalimide (BrNpA) and 6-Br-1-Hexene (BrHexene). Several PVP-and PNVCL-based copolymers emit notable RTP signals with diverse emission properties. The polymer matrices provide rigid environment for the phosphors, which restricts thermal motions and results in significant RTP emissions.PVP-BrNpA, PVP-BA, and PVP-BrHexene, which have five-membered lactam rings in their polymer chains, were Pure organic, amorphous room-temperature phosphorescent (RTP) materials have aroused great attention because of their easy preparation and wide applications. Herein, several metal-free, amorphous, lactam phosphorescent copolymers are prepared. Copolymers of N-vinylpyrrolidone (NVP) and N-vinylcaprolactam (NVCL) with small amounts of monomers exhibit diverse RTP emissions. The rigid polymer matrices of poly(N-vinylpyrrolidone) (PVP) and poly(N-vinylcaprolactam) (PNVCL) effectively help to inhibit nonradiative transition process of phosphors, which enhances the RTP emission. Furthermore, outstanding biocompatibility, low cost, and highly hydrophilic ch...

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