High-performance full-color afterglow organic light-emitting diodes with tri-mode emission and efficient energy transfer

Afterglow organic light-emitting diodes (OLEDs) with persistent emission after switching off the applied voltage have garnered extensive attention recently, but the available organic afterglow materials for electroexcitation remains rare, along with low device performance. Here, we report a series of high-performance full-color afterglow OLEDs by employing tri-mode afterglow molecule as emitting layer doped with various phosphorescent complexes in a simplified thick-layer OLED architecture. The tri-mode afterglow by transforming the long-lived ultralong phosphorescence to phosphorescence and fluorescence through thermally activated exciton release and reverse intersystem crossing promotes significantly the afterglow efficiency. Indeed, the tri-mode afterglow OLEDs display blue to cyan afterglow with lifetime up to 253 ms and maximum external quantum efficiency (EQE) of 7.4%. After doping of phosphorescent complexes, efficient energy transfer from the tri-mode afterglow host to phosphor dopants results in highly bright and efficient green, yellow and red afterglow OLEDs with the maximum lifetime of 132 ms, total EQE of 24%, and afterglow EQE of 3.6%, representing the highest efficiencies reported so far of afterglow OLEDs. This study opens exciting prospects for the development of high-performance afterglow OLEDs, leveraging unique properties of organic semiconductors with rich triplet excited state behaviors for advanced optoelectronic applications and light-emitting technologies.