Thermally Activated Delayed Fluorescent (TADF) Mono‐Polymeric OLED with Higher EQE over Its TADF Repeating Unit

• Published in: Macromolecular chemistry and physics 2022-06, Vol.223 (11), p.n/a
• Main Authors: Zhang, Jiasen, Wei, Qiang, Lyu, Lingling, Cao, Liang, Zhao, Mengyu, Fei, Nannan, Wang, Tao, Ge, Ziyi
• Format: Article
• Language: English
• Subjects: Carbazoles; donor–acceptor structures; Fluorescence; Organic light emitting diodes; Polymers; Quantum efficiency; solution‐processes; thermally activated delayed fluorescence
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.202200023

Thermally activated delayed fuorescent (TADF) polymers are very suitable for fabricating highly efficient solution‐processed organic light emitting diodes (OLEDs). TADF homopolymers with simple structures are much preferred for preparation, but due to the triplet–triplet annnihilation, most TADF homopolymeric OLED exhibits lower external quantum efficiency (EQE) than its TADF repeating unit. Herein, two series small molecules (CzPhO and PxPhO) and their related mono‐polymers (PCzPhO and PPxPhO) are designed and synthesized for comparison. Among them, phenoxazine‐based materials show TADF properties compared to the carbazole‐based materials, which may be due to the enhanced electron donating ability of phenoxazine unit. In addition, the solution‐processed devices based on phenoxazine‐based polymer PPxPhO give excellent performance compared to their counterparts with the EQEmax of 11.8%. Herein, a method to derive TADF property from a non‐TADF molecule by enhancing electron donating ability is proposed. And the related TADF homopolymers are also synthesized. Among them, the polymer PPxPhO‐based solution‐processed OLED has the best performance when compared with other conterparts, with Lmax and EQEmax of 7927 cd m−2 and 11.8%, respectively.