Ancillary ligand increases the efficiency of heteroleptic Ir-based triplet emitters in OLED devices

Baek, Seung-yeol; Kwak, Seung‐Yeon; Kim, Seoung-Tae; Hwang, Kyu Young; Koo, Hyun Cheol; Son, Won‐Joon; Choi, Byoungki; Kim, Sunghan; Choi, Hye Jung; Baik, Mu‐Hyun

doi:10.1038/s41467-020-16091-1

Cited by 32 publications

(33 citation statements)

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“…Thus, singlet and triplet excitons generated under electrical excitation in electroluminescent devices can be used through the singlet harvesting effect − to reach up to a 100% internal efficiency, whereas a limit of only 25% is expected in the absence of TADF or phosphorescence. Although phosphorescent emitters can achieve such an efficiency through a triplet harvesting mechanism, they often require high-cost and less abundant Ir(III) or Pt(II) ions in their structure. − Conversely, the most studied TADF emitters correspond to purely organic compounds ,− or low-cost metal-based inorganic complexes containing Cu I ,,− or Ag I . ,,− Hence, a deep understanding and identification of the variables controlling TADF is required to design and develop high-performance emitters for technological applications.…”

Section: Introductionmentioning

confidence: 99%

Nuclearity Control for Efficient Thermally Activated Delayed Fluorescence in a Cu^I Complex and its Halogen-Bridged Dimer

et al. 2021

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We report on the thermally activated delayed fluorescence (TADF) properties of a novel iodine-bridged Cu I dimeric complex and its structurally related monomer. The chemical environment around the copper centers is identical in both complexes, providing a clean comparison to understand the effect of nuclearity in Cu I emitters. Efficient room-temperature TADF (≈80% of the total emission) is observed in both compounds. Similar singlet−triplet splittings were found for the monomer and the dimer (554 and 583 cm −1 , respectively), while the dimer triplet lifetime (90.0 μs) was longer than that of the monomer (46.0 μs). Experimental findings were rationalized by time-dependent density functional theory and complete active space self-consistent field calculations, identifying key structural factors determining TADF properties such as the key role of iodine in spin−orbit coupling mixing and the importance of near degeneracies in donor and acceptor orbitals for promoting state mixing. Unavoidable modifications associated with a change in nuclearity (e.g. intermolecular interactions, molecular charge, or modification of some binding motifs) can be also designed to promote TADF performance.

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Section: Introductionmentioning

confidence: 99%

Nuclearity Control for Efficient Thermally Activated Delayed Fluorescence in a Cu^I Complex and its Halogen-Bridged Dimer

et al. 2021

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“…Accordingly, the configurations of fac -homoleptic and heteroleptic with symmetric ancillary ligand are relatively recommended and are just right now the main streams in NIR Ir(III) complexes. In addition, the ligand structures are better to be rigid to keep symmetry and avoid distortions in excited states ( Baek et al., 2020 ; Sajoto et al., 2009 ; Zhou et al., 2016 ). Increase the oscillator strength between 1 MLCT and S 0 .…”

Section: Basic Knowledge and Theoretical Backgroundmentioning

confidence: 99%

“…This structural distortion may reduce the energy gap between the 3 MLCT and 3 MC states and thus accelerate the nonradiative decay. An effective way to inhibit the structural distortion is reported by adding steric hindrance on the non-chromophore ancillary ligand ( Baek et al., 2020 , see section the ancillary ligand in details).…”

Section: Basic Knowledge and Theoretical Backgroundmentioning

confidence: 99%

“…Since it is more frequently used than any other ancillary ligands ( Figure 3 ), the heteroleptic complexes-based acac can be seen as preferences for cyclometalated ligands. Some bulkier acac derivatives were employed to suppress possible distortions in excited states, thus lowering the k nr for red-emitting Ir(III) complexes as shown in Figure 10 ( Baek et al., 2020 ). Besides, picolinic was also used as non-chromophore ancillary ligand in some cases.…”

Section: Molecular Designs For Nir-emitting Ir(iii) Complexesmentioning

confidence: 99%

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Near-infrared emitting iridium complexes: Molecular design, photophysical properties, and related applications

Zhang

Qiao

2021

iScience

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Summary Organic light-emitting diodes (OLEDs) have become popular displays from small screens of wearables to large screens of televisions. In those active-matrix OLED displays, phosphorescent iridium(III) complexes serve as the indispensable green and red emitters because of their high luminous efficiency, excellent color tunability, and high durability. However, in contrast to their brilliant success in the visible region, iridium complexes are still underperforming in the near-infrared (NIR) region, particular in poor luminous efficiency according to the energy gap law. In this review, we first recall the basic theory of phosphorescent iridium complexes and explore their full potential for NIR emission. Next, the recent advances in NIR-emitting iridium complexes are summarized by highlighting design strategies and the structure-properties relationship. Some important implications for controlling photophysical properties are revealed. Moreover, as promising applications, NIR-OLEDs and bio-imaging based on NIR Ir(III) complexes are also presented. Finally, challenges and opportunities for NIR-emitting iridium complexes are envisioned.

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“…Organic light-emitting diodes (OLEDs) are considered and applied as a feasible technology in high-quality display, solid-state lighting sources (SSLs), and near-infrared (NIR) applications, owing to the excellent advantages including high efficiency, low power consumption, and flexibility. ( Baek et al, 2020 ; Helander et al, 2011 ; Wang et al, 2011 ; Wang et al, 2020 ; Xu et al, 2017 ; Greiner et al, 2012 ; Zheng et al, 2013 ; Xu et al, 2021a ). Nevertheless, previous studies usually adopted complicated fabricated processes and device structures of OLEDs, which impede the popularizing of this promising technology.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Structure and Energy Transfer Process of Undoped Ultrathin Emitting Nanolayers Within Interface Exciplexes

Wang

et al. 2022

Front. Chem.

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Organic light-emitting diodes (OLEDs) have great potential for display, lighting, and near-infrared (NIR) applications due to their outstanding advantages such as high efficiency, low power consumption, and flexibility. Recently, it has been found that the ultrathin emitting nanolayer technology plays a key role in OLEDs with simplified structures through the undoped fabricated process, and exciplex-forming hosts can enhance the efficiency and stability of OLEDs. However, the elementary structure and mechanism of the energy transfer process of ultrathin emitting nanolayers within interface exciplexes are still unclear. Therefore, it is imminently needed to explore the origin of ultrathin emitting nanolayers and their energy process within exciplexes. Herein, the mechanism of films growing to set ultrathin emitting nanolayers (<1 nm) and their energy transfer process within interface exciplexes are reviewed and researched. The UEML phosphorescence dye plays a key role in determining the lifetime of excitons between exciplex and non-exciplex interfaces. The exciplex between TCTA and Bphen has longer lifetime decay than the non-exciplex between TCTA and TAPC, facilitating exciton harvesting. The findings will be beneficial not only to the further development of OLEDs but also to other related organic optoelectronic technologies.

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Ancillary ligand increases the efficiency of heteroleptic Ir-based triplet emitters in OLED devices

Cited by 32 publications

References 24 publications

Nuclearity Control for Efficient Thermally Activated Delayed Fluorescence in a Cu^I Complex and its Halogen-Bridged Dimer

Nuclearity Control for Efficient Thermally Activated Delayed Fluorescence in a Cu^I Complex and its Halogen-Bridged Dimer

Near-infrared emitting iridium complexes: Molecular design, photophysical properties, and related applications

Understanding the Structure and Energy Transfer Process of Undoped Ultrathin Emitting Nanolayers Within Interface Exciplexes

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Ancillary ligand increases the efficiency of heteroleptic Ir-based triplet emitters in OLED devices

Cited by 32 publications

References 24 publications

Nuclearity Control for Efficient Thermally Activated Delayed Fluorescence in a CuI Complex and its Halogen-Bridged Dimer

Nuclearity Control for Efficient Thermally Activated Delayed Fluorescence in a CuI Complex and its Halogen-Bridged Dimer

Near-infrared emitting iridium complexes: Molecular design, photophysical properties, and related applications

Understanding the Structure and Energy Transfer Process of Undoped Ultrathin Emitting Nanolayers Within Interface Exciplexes

Contact Info

Product

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Nuclearity Control for Efficient Thermally Activated Delayed Fluorescence in a Cu^I Complex and its Halogen-Bridged Dimer

Nuclearity Control for Efficient Thermally Activated Delayed Fluorescence in a Cu^I Complex and its Halogen-Bridged Dimer