Recent Advances of Aromatic Cyclic Imide/Amide Acceptors in Thermally Activated Delayed Fluorescent Materials for Organic Light-Emitting Diodes

Abstract

Aromatic imide/amide-based optoelectronic materials are attracting increasing attention due to the unique advantages of imide/amide groups in modulating properties such as electron-withdrawing ability, excited-state properties, molecular configuration, intermolecular interactions, and packing pattern. This review systematically summarizes recent advances in thermally activated delayed fluorescence (TADF) materials based on aromatic cyclic imide/amide for high-efficiency organic light-emitting diodes, with a focus on the material design strategies and structure–property relationships. The design and development of aromatic imide acceptors are comprehensively outlined. Their structural configurations and energy level characteristics, along with the progress of corresponding TADF molecules, are examined and categorized by the ring size of the imide group (including five-, six-, and seven-membered aromatic cyclic imides). Subsequently, the design strategies for TADF molecules based on aromatic amides are discussed, revealing that the N-R-N-phenylbenzamide framework is the most common structural motif among reported emitters. Finally, an in-depth analysis of the structural designs of aromatic imide/amide molecules that achieved high external quantum efficiencies across various emission wavelength ranges is conducted.