Benzonitrile/pyridylbenzoimidazole hybrid electron-transport material for efficient phosphorescence and TADF OLEDs

A new electron-transport material (ETM) of iTPyBI-CN is developed through non-catalytic C-N coupling reaction from 2,4,6-trifluorobenzonitrile and 2-pyridyl-1H-benzo[d]imidazole. Compared to the commercial ETM of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI), the donor-acceptor type iTPyBI-CN exhibits a more twisted geometry for comparable triplet energy, higher LUMO and slightly deeper HOMO levels. In both phos-phorescence and thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs), de -vices based on iTPyBI-CN as ETM demonstrates better electroluminescence (EL) efficiencies than TPBI, with maximum external quantum efficiency (EQE) of 20.2, 22.0, 16.3 and 16.1 % versus 16.4, 18.9, 11.0 and 3.0 % for various phosphorescent and TADF OLEDs.