High-Efficiency Near-Infrared OLED Enabled by Exciplex-Forming Hosts and a New Organic Fluorescent Emitter

Yi Yun Chen, Yu Cheng Kung, Miaosheng Wang, Yuan Chih Lo, Yao Te Chia, Chun Kai Wang, Deng Gao Chen, Ju Ting Cheng, Pi Tai Chou*, Chichi Wu, Elise Y. Li, Bin Hu*, Wen Yi Hung*, Ken Tsung Wong*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Two blends comprising new dicyanopyrazine-based acceptors (m-CN and p-CN) and a carbazole-based donor CPTBF are explored for exciplex formation. The CPTBF:m-CN and CPTBF:p-CN blends show the signature red-shifted emission together with the delayed fluorescence observed in time-resolved measurement, manifesting the characteristics of thermally activated delayed fluorescence (TADF). The electroluminescence (EL) device employing CPTBF:m-CN (CPTBF:p-CN) blend as the emitting layer (EML) achieved an EQE of 5.22% (2.05%) with the EL λmax centered at 607 nm (625 nm). The exciplex excitons can be efficiently extracted by a new benzobisthiadiazole-based near-infrared (NIR) emitter DCzPBBT, where a device is configured with CPTBF:m-CN: (5 wt.%) DCzPBBT as the EML to achieve a high EQE of 5.32% and an EL λmax 758 nm. Further increase of the doping concentration to 10 wt.% of DCzPBBT exhibits a bathochromic shifted EL λmax to 772 nm with 94% spectral coverage in the NIR (>700 nm) region, while the device EQE retains at 4.06%. The superior device performance stems from the highly efficient energy transfer between the exciplex-forming host and NIR dopant together.

Original languageEnglish
Article number2303131
JournalAdvanced Optical Materials
Volume12
Issue number16
DOIs
Publication statusPublished - 2024 Jun 6

Keywords

  • exciplex
  • intermolecular charge transfer
  • near-infrared
  • thermally activated delayed fluorescence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

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