1. 2,3-Dicyanopyrazino phenanthroline enhanced charge transfer for efficient near-infrared thermally activated delayed fluorescent diodes.
- Author
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Wang, Huiqin, Zhao, Bingjie, Qu, Chao, Duan, Chunbo, Li, Zhe, Ma, Peng, Chang, Peng, Han, Chunmiao, and Xu, Hui
- Subjects
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DELAYED fluorescence , *ORGANIC light emitting diodes , *CHARGE transfer , *LIGHT emitting diodes , *PHENANTHROLINE , *TRIPHENYLAMINE , *DIODES - Abstract
[Display omitted] • Near-infrared TADF emission from phenanthroline based molecule is demonstrated. • NIR emission and radiation efficiency are balanced in CNPP-TPA. • Strong NIR emission peaked at 701 nm with PLQY of 96.5% is realized. • A maximum EQE (8.69%) of vacuum-evaporated device peaked at 684 nm is achieved. • A maximum EQE (2.02%) of spin-coated device peaked at 700 nm is achieved. Efficient thermally activated delayed fluorescence (TADF) emitters are of practical significance for realizing high-performance organic light emitting diodes (OLEDs), which remains the great challenge for near-infrared (NIR) emitters because of their narrow bandgap worsened non-radiative transition. Herein, a NIR TADF molecule (CNPP-TPA) is reported, composed of 2,3-dicyanopyrazino phenanthroline (CNPP) as acceptor and triphenylamine as donor. The strong electron-withdrawing effect of CNPP and intramolecular hydrogen bond endow CNPP-TPA with efficient NIR photoluminescence emission peaked at 701 nm with a high photoluminescence quantum yield of 96.5%, owing to rapid singlet radiation and effective reverse intersystem crossing. Vacuum -evaporated and spin-coated organic light-emitting diodes exhibit the NIR emissions respectively peaked at 684 nm and 700 nm, corresponding to Commission International de L'Eclairage (CIE) coordinates of (0.68, 0.31) and (0.69, 0.30), respectively. Significantly, these two devices achieved the state-of-the-art external quantum efficiencies of 8.69% and 2.02%. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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