Efficient deep-blue fluorescent OLEDs based on a D‒π‒A emitter profiting from intramolecular hydrogen bonds and a hybridized excited state.

Abstract

High performance deep-blue emitters with a Commission International de l'Eclairage (CIE) coordinate of CIEy ≤ 0.08 are highly desired in ultrahigh-definition displays. Herein, we designed and synthesized an efficient D‒π‒A deep-blue emitter, 2-(6-([1,1':3',1''-terphenyl]-5'-yl)pyridin-3-yl)-1-phenyl-1H-phenanthro[9,10-d] imidazole (mPTPH), using the synergistic effect of intramolecular hydrogen bond (H-bond) and hybridized excited state. Single-crystal structure analysis confirmed that there exist intra- and intermolecular H-bond interactions which could inhibit the structure vibration and increase photoluminescence efficiency. The photophysical and theoretical results show that mPTPH exhibited hybridized local and charge-transfer (HLCT) feature with strong deep-blue emission. Ultimately, the non-doped device based on mPTPH exhibited high maximum luminance of 20610 cd m-2. The doped device achieved high maximum external quantum efficiency of 5.4% and small efficiency roll-off with deep-blue emission peak of 413 nm and CIE coordinate of (0.16, 0.08).