Nondoped organic light-emitting diodes (OLEDs) have drawn enormous attention for their merits of process simplicity, reduced fabrication cost, and phase stability. Herein, a novel approach of utilizing intermolecular hydrogen bonding for enhancing performance of nondoped OLEDs with a new thermally activated delayed fluorescence (TADF) emitter 10-(4-(2,6-di(pyrimidin-5-yl)pyridin-4-yl)phenyl)-10H-phenoxazine (DPmP-PXZ) is investigated. Endowing with suitable intermolecular hydrogen bonds linking the ends of neighboring DPmP-PXZ molecules, the molecules tend to form extended 1D molecular chain in solid. This 1D structure effectively keeps the electron-rich PXZ cores in neighboring molecules apart from each other such that triplet-related exciton quenching can be well suppressed. In addition, it also improves the balance of carrier mobilities and the optical out-coupling from the emitting layer. With these merits, OLEDs using DPmP-PXZ as a dopant emitter, from 10 to 100 wt%, can maintain high external quantum efficiencies (EQEs) of over 20%. More importantly, its nondoped OLED shows a yellow emission and an excellent maximum EQE of 21.8% with little efficiency roll-off which is even comparable with state-of-the-art yellow OLEDs. These results provide new insight on the role of hydrogen bonding in molecular packing and its subsequent influences on the performance of OLEDs.
