Design of Efficient Benzosilole Derivatives for Tuning High‐Performance HLCT OLEDs

Abstract Properties of hybridized local and charge‐transfer (HLCT) materials can be tuned by adjusting locally excited (LE) and charge‐transfer (CT) components, resulting in either quasi‐equivalent hybridization or non‐equivalent hybridization. These HLCT materials are easily designed on the molecular level to be applied in organic light‐emitting diodes (OLEDs), which have advantages in the aspects of external quantum efficiency (EQE), efficiency roll‐off, and color purity. In previous work, an HLCT silole derivative with an electron donor (D) – acceptor (A) structure modified at 1‐position achieved a breakthrough in the external quantum efficiency (EQE) of 9.1%. Whereas such molecular design generally leads to low PLQYs, limiting the further improvement of EQE. Thinking a more rigid structure design strategy, in this work, silole is replaced with a more rigid benzosilole structure that is selectively modified by a carbazole (Cz) or 9,9‐dimethyl‐9,10‐dihydroacridine (Ac) unit as donor and triazine (TRZ) unit as the acceptor, leading to higher PLQYs of the CT‐like HLCT molecule DCz‐BS‐TRZ , and quasi‐equivalent HLCT molecule DAc‐BS‐TRZ . Among these two molecules, the DCz‐BS‐TRZ ‐based OLED device has shown a remarkable 13% EQE max , which is the highest EQE for silole‐based OLEDs.