Bipolar Blue Host Emitter with Unity Quantum Yield Allows Full-Exciton Radiation in Single-Emissive-Layer Hybrid White Organic Light-Emitting Diodes

Phosphorescence/fluorescence hybrid white organic light-emitting diodes (OLEDs) are highly appealing for solid-state lighting. One major challenge is how to fully utilize the electrically generated excitons for light output. Herein, an efficient strategy to realize full exciton radiation is successfully revealed by judicious molecular design and suitable device engineering. A blue host emitter TP-PPI is designed and synthesized, exhibiting a near 100% photoluminescence quantum yield and a high triplet energy level enabling high-performance blue fluorescence and sensitization of yellow phosphorescent dopant. Full exciton radiation in hybrid white OLEDs is demonstrated with single emitting-layer formed by doping a yellow phosphor (PO-01) into TP-PPI. Near 100% exciton utilization and state-of-the-art EQE of 27.5% are achieved with the high efficiency blue-emitting host and an electron-trap engineered device architecture.