Water‐soluble phosphorescent polymers with time‐dependent organic afterglow covering a broad spectrum

Abstract Materials exhibiting a time‐dependent organic afterglow across a broad spectrum have significant potential in various photonic applications, yet achieving this remains a challenge. This work reports on a series of water‐soluble polymers, which were synthesized by incorporating a pyrene‐based triphenylphosphine salt into polyacrylamide. These polymers exhibit time‐dependent room‐temperature phosphorescence (RTP), with a color transition in their afterglow from red to orange, yellow, and green. Experimental results reveal that the coexistence of isolated and aggregated states is crucial for this time‐dependent persistent RTP. Remarkably, these materials can achieve RTP in an amorphous state and have excellent water solubility. Taking advantage of these properties, security inks were produced by dissolving these polymers in aqueous solution, facilitating the successful printing of high‐resolution patterns over large areas using a commercial inkjet printer. Finally, we demonstrate the fabrication of transparent films with tunable, persistent RTP colors, highlighting the potential of these materials for multi‐dimensional optical encoding and security applications.