Mild donor-π-mild acceptor (mD-π-mA) benzimidazole-based deep blue fluorophores with hybridized local and charge transfer (HLCT) excited states for OLEDs

The design of an efficient pure blue emitter to achieve stable, long operating organic light-emitting diode (OLED) devices still poses a significant challenge. Although through phosphorescence and thermally activated delayed fluorescence concepts, stable monochrome green red OLEDs can be realized, the has been All efforts so far have resulted in severe efficiency roll-off limited device lifetime. Therefore, developing blue-emitting materials with little or no is great importance for commercial display OLEDs. In this context, we designed synthesized two that are improved photophysical properties: 2-(4″-(1-(4-(tert-butyl)phenyl)-4,5-diphenyl-1H-imidazol-2-yl)-[1,1′:4′,1′′-terphenyl]-4-yl)-1-phenyl-1H-benzo[d]imidazole (PTBIBI) 2-(4′′-(4,5-diphenyl-1-(3-(trifluoromethyl)phenyl)-1H-imidazol-2-yl)-[1,1′:4′,1′′-terphenyl]-4-yl)-1-phenyl-1H-benzo[d]imidazole (MCFBIBI). These emitters possess hybrid local charge-transfer (HLCT) state high photoluminescence quantum yields (>90%). doped based on PTBIBI reasonably good performance Commission International de l’Eclairage (CIE) coordinates (0.15, 0.06) deep region g maximum luminance 6559 cd m−2 at very low turn-on voltage (3.2 V) corresponding bandgap value emitter.