Work

Secondary Donor Engineering for High‐Efficiency Orange‐Red Thermally Activated Delayed Fluorescence Emitters

Year: 2025

Type: article

Abstract: Achieving efficient orange‐red emission in thermally activated delayed fluorescence (TADF) emitters remains challenging due to the hard to achieve great balance between a small singlet‐triplet energy gap and high radiative decay rates. In this study, a modification site engineering strategy for secondary donors to optimize excited‐state properties for orange‐red emitters is proposed. Two isomeric emitters, ND28DBT and ND37DBT, were synthesized by introducing dibenzothiophene (DBT) units at different positions of a naphthalimide–dimethylacridine (NAI–DMAc) core. The theoretical analysis indicates that ND37DBT possesses a more favorable excited‐state configuration, which facilitates an efficient reverse intersystem crossing (RISC) process and accelerates the radiative decay rate. As a result, ND37DBT showed a high photoluminescence quantum yield (PLQY) (70%), a fast RISC rate (6.25 × 105 s−1), and an excellent external quantum efficiency (EQE) (22.1%) with minimal roll‐off in 100 cd m−2. This work demonstrates that precise control of secondary donor modification sites offers a powerful molecular design strategy for developing high‐efficiency orange‐red TADF materials.

Source: Chemistry - A European Journal

DOI: 10.1002/chem.202501391

Authors: Lei Hua, Han Wu, Shouke Yan, Weiguo Zhu, Zhongjie Ren, Yafei Wang