Tetradentate C∧C∧N∧N Ligand-Containing Gold(III) Complexes with Orange to Deep-Red Thermally Activated Delayed Fluorescence (TADF) and Their Application in Organic Light-Emitting Devices
- Wing-Kei KwokWing-Kei KwokInstitute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaMore by Wing-Kei Kwok
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- Lok-Kwan LiLok-Kwan LiInstitute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaMore by Lok-Kwan Li
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- Shiu-Lun LaiShiu-Lun LaiInstitute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaMore by Shiu-Lun Lai
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- Ming-Yi LeungMing-Yi LeungInstitute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaHong Kong Quantum AI Lab Limited, 17 Science Park West Avenue, Pak Shek Kok, Hong Kong, P. R. ChinaMore by Ming-Yi Leung
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- Wai Kit TangWai Kit TangInstitute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaMore by Wai Kit Tang
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- Shun-Cheung ChengShun-Cheung ChengDepartment of Chemistry, City University of Hong Kong, Kowloon, Hong Kong, P. R. ChinaMore by Shun-Cheung Cheng
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- Man-Chung TangMan-Chung TangInstitute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaMore by Man-Chung Tang
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- Wai-Lung CheungWai-Lung CheungInstitute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaMore by Wai-Lung Cheung
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- Chi-Chiu Ko*Chi-Chiu Ko*Email: [email protected]. Tel: +(852) 3442 6958.Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong, P. R. ChinaMore by Chi-Chiu Ko
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- Mei-Yee Chan*Mei-Yee Chan*Email: [email protected]Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaHong Kong Quantum AI Lab Limited, 17 Science Park West Avenue, Pak Shek Kok, Hong Kong, P. R. ChinaMore by Mei-Yee Chan
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- Vivian Wing-Wah Yam*Vivian Wing-Wah Yam*Email: [email protected]. Tel: +(852) 2859-2153. Fax: +(852) 2857-1586.Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. ChinaHong Kong Quantum AI Lab Limited, 17 Science Park West Avenue, Pak Shek Kok, Hong Kong, P. R. ChinaMore by Vivian Wing-Wah Yam
Abstract
A new class of thermally activated delayed fluorescence (TADF) tetradentate C∧C∧N∧N ligand-containing gold(III) complexes containing acridinyl moieties has been designed and synthesized. These complexes exhibit orange-red to deep-red emission with photoluminescence quantum yields (PLQYs) of up to 0.76 in solid-state thin films. Short excited-state lifetimes of ≤2.0 μs and large radiative decay rate constants (kr) in the order of 105 s–1 have also been found in the complexes. High-performance solution-processed and vacuum-deposited organic light-emitting devices (OLEDs) based on these complexes have been fabricated, demonstrating high maximum external quantum efficiencies (EQEs) of 12.2 and 12.7%, respectively, which are among the best values ever reported for red-emitting gold(III)-based OLEDs. In addition, satisfactory operational half-lifetime (LT50) values of up to 34,058 h have been attained in these red-emitting devices. It is found that the operational stability is strongly dependent on the choice of functional groups on the acridinyl moieties, of which the incorporation of −O− and −S− linkers can effectively prolong the LT50 value by an order of magnitude. The TADF properties of the complexes are substantiated by the hypsochromic shift in emission energies and the remarkable enhancement in the emission intensity upon increasing temperature. The TADF properties have also been supported by temperature-dependent ultrafast transient absorption studies, with the direct observation of reverse intersystem crossing (RISC) and the determination of the activation parameters for the very first time, together with their excited-state dynamics.
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