Organic Afterglow Microgels Exhibiting 9.33 s Phosphorescence Lifetime under Ambient Conditions

Abstract Organic room‑temperature phosphorescence (RTP) materials attract interest for bioimaging, anti‑counterfeiting, and data storage. Yet, achieving stable RTP in water‑rich, oxygen‑permeable hydrogels is difficult due to triplet quenching and fast nonradiative decay. Here, we introduce a microfluidics‑assisted method to build organic afterglow microgels with ultralong phosphorescence in air. Deuterated coronene is loaded into poly(methyl methacrylate) latex nanoparticles and then embedded in a crosslinked polymer network, creating a hierarchical confinement that suppresses triplet nonradiative transitions and oxygen quenching. The microgels show phosphorescence duration up to tens of seconds, with a record 9.33 s lifetime for organic microgel systems, arising from the localized triplet state of deuterated coronene. They also exhibit reversible humidity response: swelling quenches, and drying restores phosphorescence. This strategy offers a general route to high‑performance, stimuli‑responsive organic RTP materials for flexible optoelectronics and intelligent sensing.