Rational Molecular Design for Efficient Exciton Harvesting, and Deep-Blue OLED Application

The efficient deep-blue luminogens with hybrid local and charge transfer (HLCT) excited state have drawn much attention for their potential in the full utilization of excitons with the corresponding excellent electroluminescent (EL) performance. However, almost all luminogens reported so far are phenanthroimidazole derivatives and the simplex molecular structures constrain their further development in a large degree. Here, a new kind of deep-blue HLCT system based on triphenylbenzene is successfully designed and synthesized. Thanks to the balanced HLCT character, the exciton utilizing efficiencies of Cz-TPB and CzPh-TPB can be up to 86% and 85% with the Commission International de l'Eclairage (CIE) coordinates of (0.15, 0.09) and (0.15,0.13) in nondoped organic light emitting diodes (OLEDs), which are among the highest values for HLCT emitters. Thus, this report might open up a new approach to develop low-cost, high-efficiency deep-blue materials with HLCT character.