Details

Autor(en) / Beteiligte

• Chen, Jia‐Xiong
• Xiao, Ya‐Fang
• Wang, Kai
• Sun, Dianming
• Fan, Xiao‐Chun
• Zhang, Xiang
• Zhang, Ming
• Shi, Yi‐Zhong
• Yu, Jia
• Geng, Feng‐Xia
• Lee, Chun‐Sing
• Zhang, Xiao‐Hong

Titel

Managing Locally Excited and Charge‐Transfer Triplet States to Facilitate Up‐Conversion in Red TADF Emitters That Are Available for Both Vacuum‐ and Solution‐Processes

Ist Teil von

• Angewandte Chemie International Edition, 2021-02, Vol.60 (5), p.2478-2484

Auflage

International ed. in English

Ort / Verlag

Germany: Wiley Subscription Services, Inc

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Developing red thermally activated delayed fluorescence (TADF) emitters for high‐performance OLEDs is still facing great challenge. Herein, three red TADF emitters, pDBBPZ‐DPXZ, pDTBPZ‐DPXZ, and oDTBPZ‐DPXZ, are designed and synthesized with same donor–acceptor (D‐A) backbone with different peripheral groups attaching on the A moieties. Their lowest triplet states change from locally excited to charge transfer character leading to significantly enhance reverse intersystem crossing process. In particular, oDTBPZ‐DPXZ exhibits efficient TADF feature and exciton utilization. It not only achieves an external quantum efficiency (EQE) of 20.1 % in red vacuum‐processed OLED, but also realize a high EQE of 18.5 % in a solution‐processed OLED, which is among the best results in solution‐processed red TADF OLEDs. This work provides an effective strategy for designing red TADF molecules by managing energy level alignments to facilitate the up‐conversion process and thus enhance exciton harvesting. By introducing phenyl or o‐tolyl groups into different positions of the same acceptor backbone, the lowest triplet energy levels of red thermally activated delayed fluorescence emitters can be tuned from locally excited triplet (3LEA) to charge transfer triplet (3CT) states, resulting in enhancement of the rates of reverse intersystem crossing (RISC), and boosting efficiencies in both vacuum‐ and solution‐processed OLEDs.