Achieving Submicrosecond Thermally Activated Delayed Fluorescence Lifetime and Highly Efficient Electroluminescence by Fine-Tuning of the Phenoxazine–Pyrimidine Structure
Tomas Serevičius, Rokas Skaisgiris, Jelena Dodonova, Laimis Jagintavičius, Dovydas Banevičius, Karolis Kazlauskas, Sigitas Tumkevičius, Saulius Juršėnas
Abstract
and shorten the TADF lifetime down to only 800 ns in toluene solutions. An almost identical TADF lifetime of roughly 860 ns was attained also in solid films for the compound with the most rapid TADF decay in toluene despite the presence of inevitable conformational disorder. Concomitantly, the boost of fluorescence quantum efficiency to near unity was achieved in solid films due to the weakened nonradiative decay. Exceptional EQE peak values of 26.3-29.1% together with adjustable emission wavelength in the range of 502-536 nm were achieved in TADF OLEDs. Reduction of EQE roll-off was demonstrated by lowering the TADF lifetime.