Highly efficient non-doped deep-blue OLED with NTSC CIEy and negligible efficiency roll-off based on emitter possessing hydrogen bond and hybridized excited state

摘要

The efficient deep-blue organic emitters with satisfying National Television System Committee (NTSC) standard Commission Internationale de L'Eclairage (CIE) coordinate of (0.14, 0.08) are indispensable component for full-color organic light-emitting diodes (OLEDs) display. In this work, we designed and synthesized a novel deep-blue material TPIN with donor-pi-acceptor (D-pi-A) structure by utilizing triphenylamine (TPA) as donor, 1,4,5-triphenyl-1H-imidazole (PIM) as acceptor and pyridyl as pi-bridge. The pyridyl is expected to endow TPIN with multiple intra-/intermolecular hydrogen bands (H-bands) interactions which could inhibit molecular vibration and affect the radiative transition, aiming to obtain efficient deep-blue OLED with high color purity and negligible efficiency roll-off. In addition, the photophysical experiments and theoretical calculations were implemented to verify the unique hybridized excited state of TPIN. And X-ray crystallographic analysis of TPIN single-crystal indicates that there exist many C-HN and C-H center dot center dot center dot pi interactions in the stacking structure. The non-doped device based on TPIN exhibited good deep-blue electroluminescence (EL) performance with emission peak at 443 nm, corresponding to a CIE coordinate of (0.151, 0.080), and a maximum external quantum efficiency (EQEmax) of 3.71% with negligible efficiency roll-off (EQE = 3.70% @ 1000 cd m(-2)).

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