High-Efficiency Near-Infrared OLED Enabled by Exciplex-Forming Hosts and a New Organic Fluorescent Emitter
Journal
Advanced Optical Materials
Date Issued
2024-01-01
Author(s)
Chen, Yi Yun
Kung, Yu Cheng
Wang, Miaosheng
Lo, Yuan Chih
Chia, Yao Te
Wang, Chun Kai
Chen, Deng Gao
Cheng, Ju Ting
Wu, Chichi
Li, Elise Y.
Hu, Bin
Hung, Wen Yi
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.
Subjects
exciplex | intermolecular charge transfer | near-infrared | thermally activated delayed fluorescence
SDGs
Type
journal article