Self‑Protective Carbonized Polymer Dots Enabling Ultralong Room‑Temperature Phosphorescence in Strong and Tough Flexible Gels

ABSTRACT Constructing flexible ultralong room‐temperature phosphorescence (URTP) materials is highly attractive yet challenging, as flexible matrices struggle to suppress the nonradiative decay of triplet excitons. Herein, self‐protective carbonized polymer dots (CPDs) derived from carbonized polyvinyl alcohol (PVA), were embedded in a gel matrix to create flexible URTP materials. Simply tuning the alcoholysis degree of PVA to 88% and reacting it with ethylenediamine under hydrothermal conditions yields NCD 88 , which exhibits a phosphorescence lifetime of 1.05 s. This benefits from carbonyl/nitrogen clusters that promote intersystem crossing (ISC) and incompletely carbonized PVA chains that restrain nonradiative decay. This strategy effectively resolves the trade‐off between ISC efficiency and triplet exciton stabilization, enabling URTP in PVA‐based CPDs. Furthermore, by combining freeze–thaw cycling with a solvent exchange strategy, a PVA‐based deep eutectic gel was prepared, exhibiting a URTP lifetime of 0.86 s, along with high tensile strength and high toughness. Thus, this study not only resolves the challenge of nonradiative decay in PVA‐based self‐protective CPDs via simple alcoholysis regulation, but also successfully integrates URTP properties with high mechanical performance into a single gel system, providing a new strategy for developing flexible URTP materials.