Highly efficient blue organic light-emitting diodes from pyrimidine-based thermally activated delayed fluorescence emitters

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 6; no. 9; pp. 2351 - 2359
• Main Authors: Li, Bowen, Li, Zhiyi, Hu, Taiping, Zhang, Yong, Wang, Ying, Yi, Yuanping, Guo, Fengyun, Zhao, Liancheng
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2018
• Subjects: Diodes; Emitters; Fluorescence; Light emitting diodes; Organic light emitting diodes; Photoluminescence; Quantum efficiency
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/C7TC05746F

Three highly efficient blue thermally activated delayed fluorescence (TADF) emitters, 2SPAc-HPM , 2SPAc-MPM and 2SPAc-PPM , have been synthesised based on pyrimidine (PM), 2-methylpyrimidine (MPM) and 2-phenylpyrimidine (PPM) as the acceptor and 10 H -spiro[acridan-9,9′-fluorene] (2SPAc) as the donor moiety. With their appropriate molecular design, these emitters successfully achieve small singlet–triplet splitting energies for efficient reverse intersystem crossing, and exhibit high photoluminescence quantum yields. As a result, TADF OLEDs based on 2SPAc-HPM , 2SPAc-MPM and 2SPAc-PPM emit blue light peaking at 479–489 nm and generate very high external quantum efficiencies of 25.56%, 24.34% and 31.45%, respectively. The 2SPAc-PPM -based TADF OLED is also one of the very few blue TADF emitters with an external quantum efficiency of more than 30%, and it has the best OLED performance among the pyrimidine-based TADF emitters.