首页|Electron-withdrawing bulky group substituted carbazoles for blue TADF emitters: Simultaneous improvement of blue color purity and RISC rate constants

Electron-withdrawing bulky group substituted carbazoles for blue TADF emitters: Simultaneous improvement of blue color purity and RISC rate constants

扫码查看
原文链接
  • NSTL
  • Elsevier
Carbazole is a weak electron donor suitable to construct blue thermally activated delayed fluorescence (TADF) emitters, but the less repulsion effect of its five-member-ring structure can't guarantee the frontier molecular orbital separation and TADF feature. A group of carbazole-pi-triazine based blue fluorescence emitters is designed by introducing the steric hindrance groups with different electronic properties at the donor or pi-bridge. When electron-withdrawing pyridyl with moderate steric hindrance is introduced to the 1-site of 3,6-Di-tert-butyl-9Hcarbazole, PyBuCz-TRZ and PyBuCz-MeTRZ gain the blue-shifted TADF. The observed charge transfer triplet excited state within the donor ((CTD)-C-3) between carbazole and pyridyl units has different spatial orbital angular momentum and allowed spin-orbit coupling (SOC) with the charge transfer singlet excited state ((CT)-C-1) of the whole molecule from carbazole donor to triazine acceptor, thus, acting as the media state to facilitate efficient multi-channel reverse intersystem crossing (RISC) process. This is the first time to introduce an electronwithdrawing group into the 1-position of carbazole donors to construct TADF molecules, not only achieving the blue-shifted TADF at 455 nm but also improving the external quantum efficiency to 15.3% in organic lightemitting diodes. This donor strategy should be valid to design more blue TADF materials.

Blue thermally activated delayed fluorescenceElectron-withdrawing-group substitutedcarbazole donorsSteric hindrance groupIntramolecular charge transfer (ICT)Multi-channel RISCACTIVATED DELAYED FLUORESCENCELIGHT-EMITTING-DIODESCHARGE-TRANSFERHIGH-EFFICIENCYDESIGNOLEDS

Liu, Botao、Li, Jiuyan、Liu, Di、Mei, Yongqiang、Lan, Ying、Song, Kai、Li, Yixue、Wang, Jiahui

展开 >

Dalian Univ Technol

2022

10.1016/j.dyepig.2022.110329

Dyes and Pigments

Dyes and Pigments

EISCI
ISSN：0143-7208
年,卷(期)：2022.203
  • 9
  • 49