High-performance near-infrared OLEDs maximized at 925 nm and 1022 nm through interfacial energy transfer

High-performance near-infrared OLEDs maximized at 925 nm and 1022 nm through interfacial energy transfer

31 May 2024 | Chieh-Ming Hung, Sheng-Fu Wang, Wei-Chih Chao, Jian-Liang Li, Bo-Han Chen, Chih-Hsuan Lu, Kai-Yen Tu, Shang-Da Yang, Wen-Yi Hung, Yun Chi & Pi-Tai Chou
This study reports a significant advancement in the performance of near-infrared (NIR) organic light-emitting diodes (OLEDs) through interfacial energy transfer. By using a transfer printing technique, a layer of the near-infrared fluorescent dye BTP-eC9 is imprinted onto a thin layer of Pt(II) complex, both capable of self-assembly. The Pt(II) complex layer exhibits intense deep-red phosphorescence at ~740 nm, while the BTP-eC9 layer shows fluorescence at >900 nm. OLEDs fabricated with this bilayer architecture harvest most of the Pt(II) complex phosphorescence, which undergoes triplet-to-singlet energy transfer to the BTP-eC9 dye, resulting in high-intensity hyperfluorescence at >900 nm. The devices achieve a peak emission wavelength of 925 nm with external quantum efficiencies (EQEs) of 2.24% (1.94 ± 0.18%) and maximum radiance of 39.97 W sr\(^{-1}\) m\(^{-2}\). Comprehensive morphology, spectroscopy, and device analyses support the mechanism of interfacial energy transfer, which is also successful for the BTPV-eC9 dye (1022 nm), making bright and far-reaching the potential of hyperfluorescent OLEDs in the near-infrared region. The study highlights the importance of optimizing the donor and acceptor properties, energy level alignment, and device structure to achieve high-performance NIR OLEDs.This study reports a significant advancement in the performance of near-infrared (NIR) organic light-emitting diodes (OLEDs) through interfacial energy transfer. By using a transfer printing technique, a layer of the near-infrared fluorescent dye BTP-eC9 is imprinted onto a thin layer of Pt(II) complex, both capable of self-assembly. The Pt(II) complex layer exhibits intense deep-red phosphorescence at ~740 nm, while the BTP-eC9 layer shows fluorescence at >900 nm. OLEDs fabricated with this bilayer architecture harvest most of the Pt(II) complex phosphorescence, which undergoes triplet-to-singlet energy transfer to the BTP-eC9 dye, resulting in high-intensity hyperfluorescence at >900 nm. The devices achieve a peak emission wavelength of 925 nm with external quantum efficiencies (EQEs) of 2.24% (1.94 ± 0.18%) and maximum radiance of 39.97 W sr\(^{-1}\) m\(^{-2}\). Comprehensive morphology, spectroscopy, and device analyses support the mechanism of interfacial energy transfer, which is also successful for the BTPV-eC9 dye (1022 nm), making bright and far-reaching the potential of hyperfluorescent OLEDs in the near-infrared region. The study highlights the importance of optimizing the donor and acceptor properties, energy level alignment, and device structure to achieve high-performance NIR OLEDs.
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