Achieving room-temperature phosphorescence of coumarin derivatives by hydrogen-bonding networks and multicolor superfluorescence by resonance energy transfer

Room-temperature phosphorescence (RTP) materials hold promise for applications in bioimaging, anti-counterfeiting, and optoelectronics , yet the design of purely organic RTP materials remains challenging due to significant non-radiative deactivation pathways. This study demonstrates a hydrogen-bonding strategy to suppress non-radiative transitions. Photophysical characterizations revealed that CCA/PAA exhibits green afterglow with a lifetime of 374 ms, while the BrCCA/PAA film achieved an enhanced quantum yield of 27.88 % due to the heavy-atom effect of the bromine. Further, by incorporating fluorescent dyes into CCA/PAA, multicolor Superfluorescence was achieved through triplet-to-singlet resonance energy transfer . These findings demonstrated the capability to tune afterglow colors and lifetimes by varying the doping ratios and energy acceptor types. This work not only provides insights into the role of hydrogen bonding and heavy-atom effects in RTP materials but also offers a pathway for designing advanced optical materials with tunable and high-performance characteristics. • Coumarin-doped PAA achieved RTP via hydrogen bonds stabilizing triplet excitons and suppressing non-radiative decay. • CCA/PAA showed green afterglow (374 ms), while BrCCA/PAA enhanced RTP (27.88 %, quantum yield) via the heavy atom effect. • Multicolor superfluorescence was achieved by doping RhB, Rh6G, and NaFl into CCA/PAA through TS-FRET.