Structure–Performance Investigation of Thioxanthone Derivatives for Developing Color Tunable Highly Efficient Thermally Activated Delayed Fluorescence Emitters

详细信息    查看全文

• 作者：Zhiheng Wang ; Yunchuan Li ; Xinyi Cai ; Dongcheng Chen ; Gaozhan Xie ; KunKun Liu ; Yuan-Chun Wu ; Chang-Cheng Lo ; A. Lien ; Yong Cao ; Shi-Jian Su
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：April 6, 2016
• 年：2016
• 卷：8
• 期：13
• 页码：8627-8636
• 全文大小：638K
• ISSN：1944-8252

文摘

Thioxanthone derivatives consisting of undecorated carbazole as an electron donor and thioxanthone (TXO) or 9H-thioxanthen-9-one-S,S-dioxide (SOXO) as an electron acceptor in a donor–acceptor (D–A) or donor–acceptor–donor (D–A–D) structure were developed as thermally activated delayed fluorescence emitters to fabricate highly efficient fluorescent organic light emitting diodes. Their emission color was successfully tuned from blue to yellow by changing the sulfur atom valence state of the thioxanthone unit to tune intramolecular charge transfer effect. Their thermal, electrochemical, photophysical, and electroluminescent properties, and theoretical calculations were systematically investigated to illustrate the molecular structure and property relationships. Maximum external quantum efficiency (EQE) of 13.6% with Commission Internationale de L’Eclairage coordinates of (0.37, 0.57) was achieved for green light emission CzSOXO consisting of SOXO and carbazole in a D–A structure. Blue light emission CzTXO and DCzTXO consisting of TXO and carbazole in a D–A and D–A–D structure could also give EQE values exceeding 11%. Their efficiency roll-off with increasing current density was simulated by adopting triplet–triplet annihilation model, indicating that the TXO derivatives suffer more severe efficiency roll-off because of their relatively long delayed fluorescence lifetime (τ_D).