Versatile Aggregation-Enhanced Delayed Fluorescence Luminogens Functioning as Emitters and Hosts for High-Performance Organic Light-Emitting Diodes

Severe efficiency instability is still a huge challenge for most organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) molecules, frustrating their industrial application. To address this issue, herein we report two robust luminogens, 3,6-bis(9,9-dimethylacridin-10-yl)-xanthen-9-one (BDMAC-XT) and 3,6-bis(9,9-diphenylacridin-10)-yl)-xanthen-9-one (BDPAC-XT), comprised of electron-accepting 3,6-dibromoxanthen-9-one and electron-donating 9,9-dimethyl-9,10-dihydroacridine and 9,9-diphenyl-9,10-dihydroacridine. BDMAC-XT and BDPAC-XT show interesting aggregation-enhanced delayed fluorescence characteristics with excellent photoluminescence quantum yields of 96% and 94% in neat films. Nondoped OLEDs based on BDMAC-XT emit intense green light with high external quantum yields (eta(ext); 21%) and hardly any efficiency roll-off (similar to 0%) at 1000 cd m(-2). High-performance sky-blue nondoped OLEDs are achieved using BDPAC-XT as emitter, providing impressive eta(ext) values (21%). Both luminogens can also function efficiently as dopants in doped OLEDs, furnishing excellent eta(ext) values (27%) and very small efficiency roll-offs down to 3.7% at 1000 cd m(-2). Moreover, they can perform as excellent hosts for orange and red phosphorescent OLEDs, leading to eta(ext) values of up to 26% and 20%, respectively. These results demonstrate that they are promising versatile functional materials for high-efficiency nondoped and doped OLEDs with superb efficiency stability. [GRAPHICS] .