Engineering Ultrahigh‐Contrast Photoactivated Room‐Temperature Phosphorescence With a Robust and Universal Ureido‐Functionalized Siloxane Network

Photoactivated room-temperature phosphorescence (pRTP) host-guest systems have received widespread attention due to their non-invasive photoresponsiveness, high reversibility, and color tunability. However, traditional polymer hosts often lack efficient photoactivation and sufficient stability due to passive oxygen penetration. Herein, we report a ureido-functionalized siloxane network derived from the hydrolysis of γ-ureidopropyltriethoxysilane (UPTES), which serves as a universal photoactivation platform for constructing pRTP systems via doping with various phosphorescent guest molecules. The UPTES-based systems can achieve superior photoactivation efficiency through the UV-induced oxygen consumption, boosting phosphorescence intensity by up to approximately 2100-fold and extending lifetime by approximately 65-fold. This ultrahigh contrast originates from the strongly active oxygen-trapping capability of the ureido groups within the siloxane network, which is crucial for establishing the initial 'off' state of guest phosphorescence via efficient oxygen-mediated quenching of triplet excitons. Notably, owing to the dense and robust siloxane network, these systems show excellent stability, maintaining efficient pRTP performance for at least 90 days even in aqueous solutions, organic reagents, or concentrated acid. This work not only presents an ultrastable host matrix for designing ultrahigh-contrast pRTP materials, but also enables the on-demand customization of pRTP systems for advanced multi-level information encryption.