Intrinsic Narrowband Organic Afterglow

Narrowband organic afterglow materials show application in multiplexed bioimaging and others. However, materials featuring an intrinsic narrowband afterglow with an emission lifetime >100 ms remain elusive. We report a serendipitous finding of a chemical reaction from aromatic amine to luminescent acridone. Interestingly, upon doping into a suitable matrix, luminescent acridone molecules display a narrowband deep-blue afterglow with full widths at half-maximum <40 nm and CIEy < 0.08 under ambient conditions. The narrowband emission originates from the multiresonant thermally activated delayed fluorescence (MRTADF) due to the suppressed vibronic coupling and rigid molecular backbone in the acridone system. Compared to conventional ones, here the MRTADF emitters feature modest k(RISC) of 1-10 s(-1) and ultralong delayed fluorescence lifetime >100 ms, which are further fashioned into an aqueous system exhibiting high color purity, visible-light-excitable property, and potential bioapplication.