Stable, Full‐Color, Long‐Lasting Aqueous Room‐Temperature Phosphorescent Materials

Abstract Ultralong room‐temperature phosphorescent (URTP) materials have garnered significant attention in anti‐counterfeiting, optoelectronic displays, and bio‐imaging due to their unique optical properties. However, most URTP materials exhibit weak emission or are quenched in aqueous solutions. This study proposes a simple and effective strategy for preparing full‐color aqueous URTP materials using a one‐step microwave method. Guest molecules are embedded in a rigid cyanuric acid (CA) matrix formed from urea. By enhancing the conjugation of the guest molecules, a series of full‐color URTP materials is successfully produced. These materials exhibit excellent phosphorescent properties, with a maximum phosphorescent lifetime of 7.96 s. Protected by the CA matrix, they retain phosphorescence even in aqueous environments, displaying an afterglow visible to the naked eye for over 30 s in water. Additionally, under low water content conditions, the materials exhibit exceptional water‐enhanced properties, achieving a phosphorescence quantum yield (PhQY) of 40.4%. Importantly, these aqueous URTP materials can be prepared in just 5 min, showcasing great potential in information encryption and afterglow displays.