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Hatanaka M, Kato H, Sakai M, Kariya K, Nakatani S, Yoshimura T, Inagaki T. Insights into the Luminescence Quantum Yields of Cyclometalated Iridium(III) Complexes: A Density Functional Theory and Machine Learning Approach. J Phys Chem A 2023; 127:7630-7637. [PMID: 37651718 DOI: 10.1021/acs.jpca.3c02179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Cyclometalated iridium(III) complexes have been used in various optical materials, including organic light-emitting diodes (OLEDs) and photocatalysts, and a deeper understanding and prediction of their luminescence quantum yields (LQYs) greatly aid in accelerating material design. In this study, we integrated density functional theory (DFT) calculations with machine learning (ML) techniques to extract factors controlling LQY. Although a substantial data set of Ir(III) complexes and their LQYs is indispensable for constructing accurate ML models to predict LQYs, generating this type of data set is challenging due to the complexities associated with ab initio calculations of LQYs. To address this issue, we investigated the nonradiative decay process of nine Ir(III) complexes emitting blue to green, each exhibiting varying experimental LQYs, by using DFT calculations. For all nine complexes, the quenching process was induced by the rotation of the single bond in one of the ligands, which converted the six-coordinate structure to the five-coordinate structure. Since the decay mechanism was common for the nine Ir(III) complexes, parameters correlated with LQYs could be used as objective variables instead of LQYs. Based on this idea, we collected a data set featuring Ir(III) complexes and the energy differences between their six- and five-coordinate triplet structures, which correlated with LQYs. We also constructed ML models using the calculated LQYs as the objective variables with the parameters from the ground-state calculations as explanatory variables. The analyses of the constructed model revealed that the LUMO energy of the ligand made the most significant negative contribution to LQY. This suggests that the potential energy surface of the metal-to-ligand charge transfer (MLCT) excited state, which stabilizes the six-coordinate structure, is reduced by decreasing the energy of the unoccupied orbitals.
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Affiliation(s)
- Miho Hatanaka
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
| | - Hiromoto Kato
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
| | - Minami Sakai
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikokma, Nara 630-0192, Japan
| | - Kosuke Kariya
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
| | - Shunsuke Nakatani
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
| | - Takayoshi Yoshimura
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
| | - Taichi Inagaki
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
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Sanderson S, Vamvounis G, Mark AE, Burn PL, White RD, Philippa BW. Unraveling exciton processes in Ir(ppy) 3:CBP OLED films upon photoexcitation. J Chem Phys 2021; 154:164101. [PMID: 33940818 DOI: 10.1063/5.0044177] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Emissive layers in phosphorescent organic light-emitting diodes commonly make use of guest-host blends such as Ir(ppy)3:CBP to achieve high external quantum efficiencies. However, while the Ir(ppy)3:CBP blend has been studied experimentally, crucial questions remain regarding how exciton diffusion is dependent on the distribution of the guest in the host, which can currently only be addressed at the atomic level via computational modeling. In this work, kinetic Monte Carlo simulations are utilized to gain insight into exciton diffusion in Ir(ppy)3:CBP blend films. The effects of both guest concentration and exciton density on various system properties are analyzed, including the probability of singlet excitons being converted to triplets, and the probability of those triplets decaying radiatively. Significantly, these simulations suggest that triplet diffusion occurs almost exclusively via guest-guest Dexter transfer and that concentration quenching of triplets induced by guest-guest intermolecular dipole-dipole interactions has a negligible effect at high exciton densities due to the prevalence of triplet-triplet annihilation. Furthermore, results for vacuum deposited morphologies derived from molecular dynamics simulations are compared to the results obtained using a simple cubic lattice approximation with randomly distributed guest molecules. We show that while differences in host-based processes such as singlet diffusion are observed, overall, the results on the fate of the excitons are in good agreement for the two morphology types, particularly for guest-based processes at low guest concentrations where guest clustering is limited.
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Affiliation(s)
- Stephen Sanderson
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - George Vamvounis
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Alan E Mark
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Paul L Burn
- Centre for Organic Photonics & Electronics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ronald D White
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Bronson W Philippa
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
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Bi H, Huo C, Song X, Li Z, Tang H, Griesse-Nascimento S, Huang KC, Cheng JX, Nienhaus L, Bawendi MG, Lin HYG, Wang Y, Saikin SK. Room-Temperature Phosphorescence and Low-Energy Induced Direct Triplet Excitation of Alq 3 Engineered Crystals. J Phys Chem Lett 2020; 11:9364-9370. [PMID: 33095025 DOI: 10.1021/acs.jpclett.0c02416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Crystal engineering is a practical approach for tailoring material properties. This approach has been widely studied for modulating optical and electrical properties of semiconductors. However, the properties of organic molecular crystals are difficult to control following a similar engineering route. In this Letter, we demonstrate that engineered crystals of Alq3 and Ir(ppy)3 complexes, which are commonly used in organic light-emitting technologies, possess intriguing functional properties. Specifically, these structures not only process efficient low-energy induced triplet excitation directly from the ground state of Alq3 but also can show strong emission at the Alq3 triplet energy level at room temperatures. We associate these phenomena with local deformations of the host matrix around the guest molecules, which in turn lead to a stronger host-guest triplet-triplet coupling and spin-orbital mixing.
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Affiliation(s)
- Hai Bi
- Jihua Laboratory, 13 Nanpingxi Road, Guicheng, Nanhai, Foshan, Guangdong, P.R. China
- School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Chanyuan Huo
- Jihua Laboratory, 13 Nanpingxi Road, Guicheng, Nanhai, Foshan, Guangdong, P.R. China
| | - Xiaoxian Song
- Jihua Laboratory, 13 Nanpingxi Road, Guicheng, Nanhai, Foshan, Guangdong, P.R. China
| | - Zhiqiang Li
- Jihua Laboratory, 13 Nanpingxi Road, Guicheng, Nanhai, Foshan, Guangdong, P.R. China
| | - Haoning Tang
- School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Sarah Griesse-Nascimento
- School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Kai-Chih Huang
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
| | - Ji-Xin Cheng
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
| | - Lea Nienhaus
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Moungi G Bawendi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Hao-Yu Greg Lin
- Center for Nanoscale Systems, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Yue Wang
- Jihua Laboratory, 13 Nanpingxi Road, Guicheng, Nanhai, Foshan, Guangdong, P.R. China
| | - Semion K Saikin
- Kebotix, Inc., 501 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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MATSUDA S, ITAGAKI C, ITO M, UMEDA M. Rectification Characteristics of C 60-doped 4-(2,2-diphenylethenyl)- N, N-bis(4-methylphenyl)-benzenamine Dual-layer Device. ELECTROCHEMISTRY 2020. [DOI: 10.5796/electrochemistry.20-64056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Shofu MATSUDA
- Department of Materials Science and Technology, Faculty of Engineering, Nagaoka University of Technology
| | - Chikara ITAGAKI
- Department of Materials Science and Technology, Faculty of Engineering, Nagaoka University of Technology
| | - Masamichi ITO
- Department of Materials Science and Technology, Faculty of Engineering, Nagaoka University of Technology
| | - Minoru UMEDA
- Department of Materials Science and Technology, Faculty of Engineering, Nagaoka University of Technology
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Sanderson S, Philippa B, Vamvounis G, Burn PL, White RD. Understanding charge transport in Ir(ppy)3:CBP OLED films. J Chem Phys 2019; 150:094110. [DOI: 10.1063/1.5083639] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Stephen Sanderson
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Bronson Philippa
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - George Vamvounis
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Paul L. Burn
- Centre for Organics Photonics & Electronics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ronald D. White
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
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Tanaka K, Hirose A, Tamashima K, Chujo Y. Synthesis of a Platinum Diketonate-Containing Polymer Showing Oxygen-Resistant Phosphorescence. Macromol Rapid Commun 2015; 36:684-8. [DOI: 10.1002/marc.201500104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Kazuo Tanaka
- Department of Polymer Chemistry; Graduate School of Engineering; Kyoto University; Katsura, Nishikyo-ku Kyoto 615-8510 Japan
| | - Amane Hirose
- Department of Polymer Chemistry; Graduate School of Engineering; Kyoto University; Katsura, Nishikyo-ku Kyoto 615-8510 Japan
| | - Kenji Tamashima
- Department of Polymer Chemistry; Graduate School of Engineering; Kyoto University; Katsura, Nishikyo-ku Kyoto 615-8510 Japan
| | - Yoshiki Chujo
- Department of Polymer Chemistry; Graduate School of Engineering; Kyoto University; Katsura, Nishikyo-ku Kyoto 615-8510 Japan
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