Converting thermally activated delayed fluorescence into hybridized local and charge-transfer via an addition acceptor moiety

Abstract

High-efficiency blue materials for Organic Light Emitting Diodes (OLEDs) are challenging but urgently needed, especially for solution-processed devices. Herein, based on a model compound of acridine-benzophenone, two blue materials were designed and synthesized, with the additional electron-withdrawing groups benzophenone and pentafluorobenzophenone connected to the acridine donor respectively to prepare BC and BC5F. The solution-processed OLED based on BC showed an emission peak at 486 nm, while the device with BC5F showed the electroluminescent peak at 478 nm. BC featured the thermally active delayed fluorescent (TADF) properties, but BC5F exhibited hybridized local and charge-transferring (HLCT) characteristics. This work showed that linking additional acceptors to the donor side could not only achieve deeper blue emission but also change the luminescent mechanism. Therefore, we provided a new strategy to manipulate the transition between TADF and HLCT.