Ultrapure Blue Thermally Activated Delayed Fluorescence (TADF) Emitters Based on Rigid Sulfur/Oxygen-Bridged Triarylboron Acceptor: MR TADF and D-A TADF

作者：Gao, Honglei; Shen, Shaogang; Qin, Yuanyuan; Liu, Guanhao; Gao, Teng; Dong, Xiangyu; Pang, Zhi; Xie, Xin; Wang, Pengfei; Wang, Ying^*

来源：Journal of Physical Chemistry Letters, 2022, 13(32): 7561-7567.

DOI：10.1021/acs.jpclett.2c01745

• LIGHT-EMITTING-DIODES
• HIGH-EFFICIENCY
• MOLECULES

Organic light-emitting diodes (OLEDs) still face a significant challenge in finding blue thermally activated delayed fluorescence (TADF) emitters that can achieve narrowband emission and high efficiency. In this work, we successfully design and synthesize a novel kind of TADF emitters based on rigid sulfur/oxygen-bridged triarylboron acceptor for ultrapure blue with narrowband electroluminescence. Time-dependent density functional theory (TD-DFT) calculations and photophysical results indicate the different intramolecular charge-transfer (ICT) character of two emitters. Benefiting from the rigid aromatic framework, both emitters exhibited deep-blue emission at 444 and 447 nm with a small full-width at half-maximum (fwhm) of about 33 nm, and a small singlet (S-1)-triplet (T-1) energy gap (delta EST) of 0.23 and 0.36 eV. Consequently, OLEDs based on PhCz-TOSBA and TPA-TOSBA exhibit deep blue electroluminescence at 456 nm with fwhm of about 55 nm, affording high external quantum efficiencies (EQEs) of 16.69% with CIE coordinates of (0.14, 0.15) and 16.65% with CIE coordinates of (0.14, 0.12), respectively. These findings show that PhCz-TOSBA and TPA-TOSBA are superior emitters in ultrapure blue TADF devices.

• 单位
  中国科学院研究生院; y