1
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Bhowmik S, Dutta A, Sen P. Ultrafast Intersystem Crossing in Benzanthrone: Effect of Hydrogen Bonding and Viscosity. J Phys Chem A 2024; 128:6864-6878. [PMID: 39129382 DOI: 10.1021/acs.jpca.4c03224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
Understanding the intricate factors governing intersystem crossing (ISC) in aromatic carbonyl compounds remains a long-standing interest among researchers. This study unveils the crucial roles of vibration in influencing the ISC of a typical aromatic carbonyl chromophore, benzanthrone, and how hydrogen bonding and solvent viscosity affect these vibrations and, thus, the associated ISC kinetics. We demonstrate that for benzanthrone, the ISC is exceedingly facile in an aprotic solvent, while in protic solvents, the ISC is significantly suppressed through the formation of the hydrogen-bonded state. Moreover, in a high-viscosity medium, ISC is further retarded due to restrictions of volume-changing motions, which may assist ISC. Theoretical calculations revealed that the C═O bond vibration and specific out-of-plane vibrations accompanying a volume change could be the probable coordinates for ISC. These findings provide valuable insights for tailoring the excited-state behavior of carbonyl-functionalized materials for diverse applications in photocatalysis, organic electronics, and biomedicine.
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Affiliation(s)
- Suman Bhowmik
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, Uttar Pradesh, India
| | - Abhijit Dutta
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, Uttar Pradesh, India
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, Uttar Pradesh, India
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2
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Jodra A, Marazzi M, Frutos LM, García-Iriepa C. Modulating Efficiency and Color of Thermally Activated Delayed Fluorescence by Rationalizing the Substitution Effect. J Chem Theory Comput 2024; 20:4239-4253. [PMID: 38738688 PMCID: PMC11137832 DOI: 10.1021/acs.jctc.4c00009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 04/22/2024] [Accepted: 04/25/2024] [Indexed: 05/14/2024]
Abstract
Thermally activated delayed fluorescence (TADF) constitutes the process by which third-generation organic light-emitting diodes (OLEDs) are being designed and produced. Despite several years of trial-and-error attempts, mainly driven by chemical intuition about how to improve a certain aspect of the process, few studies focused on the in-depth description of its two key properties: efficiency of the T1 → S1 intersystem crossing and further S1 → S0 emission. Here, by means of a newly developed theoretical formalism, we propose a systematic rationalization of the substituent effect in a paradigmatic class of OLED compounds, based on phenothiazine-dibenzothiophene-S,S-dioxide, known as PTZ-DBTO2. Our methodology allows to discern among geometrical and electronic effects induced by the substituent, deeply understanding the relationships existing between charge transfer, spin density, geometrical deformations, and energy modulations between electronic states. By our results, we can finally elucidate, depending on the substituent, the fate of the overall TADF process, quantitatively assessing its efficiency and predicting the color emission. Moreover, the general terms by which this methodology was developed allow its application to any chromophore of interest.
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Affiliation(s)
- Alejandro Jodra
- Departamento
de Química Analítica, Química Física e
Ingeniería Química, Grupo de Reactividad y Estructura
Molecular (RESMOL), Universidad de Alcalá, Ctra. Madrid-Barcelona, Km 33.600, Alcalá de Henares, Madrid 28871, Spain
| | - Marco Marazzi
- Departamento
de Química Analítica, Química Física e
Ingeniería Química, Grupo de Reactividad y Estructura
Molecular (RESMOL), Universidad de Alcalá, Ctra. Madrid-Barcelona, Km 33.600, Alcalá de Henares, Madrid 28871, Spain
- Instituto
de Investigación Química “Andrés M. del
Río” (IQAR), Universidad de
Alcalá, Ctra.
Madrid-Barcelona, Km 33.600, Alcalá
de Henares, Madrid 28871, Spain
| | - Luis Manuel Frutos
- Departamento
de Química Analítica, Química Física e
Ingeniería Química, Grupo de Reactividad y Estructura
Molecular (RESMOL), Universidad de Alcalá, Ctra. Madrid-Barcelona, Km 33.600, Alcalá de Henares, Madrid 28871, Spain
- Instituto
de Investigación Química “Andrés M. del
Río” (IQAR), Universidad de
Alcalá, Ctra.
Madrid-Barcelona, Km 33.600, Alcalá
de Henares, Madrid 28871, Spain
| | - Cristina García-Iriepa
- Departamento
de Química Analítica, Química Física e
Ingeniería Química, Grupo de Reactividad y Estructura
Molecular (RESMOL), Universidad de Alcalá, Ctra. Madrid-Barcelona, Km 33.600, Alcalá de Henares, Madrid 28871, Spain
- Instituto
de Investigación Química “Andrés M. del
Río” (IQAR), Universidad de
Alcalá, Ctra.
Madrid-Barcelona, Km 33.600, Alcalá
de Henares, Madrid 28871, Spain
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3
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Kim HS, Lee SH, Yoo S, Adachi C. Understanding of complex spin up-conversion processes in charge-transfer-type organic molecules. Nat Commun 2024; 15:2267. [PMID: 38480706 PMCID: PMC10937997 DOI: 10.1038/s41467-024-46406-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 02/13/2024] [Indexed: 03/17/2024] Open
Abstract
Despite significant progress made over the past decade in thermally activated delayed fluorescence (TADF) molecules as a material paradigm for enhancing the performance of organic light-emitting diodes, the underlying spin-flip mechanism in these charge-transfer (CT)-type molecular systems remains an enigma, even since its initial report in 2012. While the initial and final electronic states involved in spin-flip between the lowest singlet and lowest triplet excited states are well understood, the exact dynamic processes and the role of intermediate high-lying triplet (T) states are still not fully comprehended. In this context, we propose a comprehensive model to describe the spin-flip processes applicable for a typical CT-type molecule, revealing the origin of the high-lying T state in a partial molecular framework in CT-type molecules. This work provides experimental and theoretical insights into the understanding of intersystem crossing for CT-type molecules, facilitating more precise control over spin-flip rates and thus advancing toward developing the next-generation platform for purely organic luminescent candidates.
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Affiliation(s)
- Hyung Suk Kim
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Sang Hoon Lee
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Seunghyup Yoo
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
- International Institute for Carbon Neutral Energy Research (I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
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4
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Pope T, Eng J, Monkman A, Penfold TJ. Spin-Vibronic Intersystem Crossing and Molecular Packing Effects in Heavy Atom Free Organic Phosphor. J Chem Theory Comput 2024; 20:1337-1346. [PMID: 38272840 PMCID: PMC10867843 DOI: 10.1021/acs.jctc.3c01220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/04/2024] [Accepted: 01/04/2024] [Indexed: 01/27/2024]
Abstract
We present a detailed investigation into the excited state properties of a planar D3h symmetric azatriangulenetrione, HTANGO, which has received significant interest due to its high solid-state phosphorescence quantum yield and therefore potential as an organic room temperature phosphorescent (ORTP) dye. Using a model linear vibronic coupling Hamiltonian in combination with quantum dynamics simulations, we observe that intersystem crossing (ISC) in HTANGO occurs with a rate of ∼1010 s-1, comparable to benzophenone, an archetypal molecule for fast ISC in heavy metal free molecules. Our simulations demonstrate that the mechanism for fast ISC is associated with the high density of excited triplet states which lie in close proximity to the lowest singlet states, offering multiple channels into the triplet manifold facilitating rapid population transfer. Finally, to rationalize the solid-state emission properties, we use quantum chemistry to investigate the excited state surfaces of the HTANGO dimer, highlighting the influence and importance of the rotational alignment between the two HTANGO molecules in the solid state and how this contributes to high phosphorescence quantum yield.
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Affiliation(s)
- Thomas Pope
- Chemistry,
School of Natural and Environmental Sciences, Newcastle University, Newcastle
upon Tyne NE1 7RU, U.K.
| | - Julien Eng
- Chemistry,
School of Natural and Environmental Sciences, Newcastle University, Newcastle
upon Tyne NE1 7RU, U.K.
| | - Andrew Monkman
- Department
of Physics, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Thomas J. Penfold
- Chemistry,
School of Natural and Environmental Sciences, Newcastle University, Newcastle
upon Tyne NE1 7RU, U.K.
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5
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Mamada M, Hayakawa M, Ochi J, Hatakeyama T. Organoboron-based multiple-resonance emitters: synthesis, structure-property correlations, and prospects. Chem Soc Rev 2024; 53:1624-1692. [PMID: 38168795 DOI: 10.1039/d3cs00837a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Boron-based multiple-resonance (MR) emitters exhibit the advantages of narrowband emission, high absolute photoluminescence quantum yield, thermally activated delayed fluorescence (TADF), and sufficient stability during the operation of organic light-emitting diodes (OLEDs). Thus, such MR emitters have been widely applied as blue emitters in triplet-triplet-annihilation-driven fluorescent devices used in smartphones and televisions. Moreover, they hold great promise as TADF or terminal emitters in TADF-assisted fluorescence or phosphor-sensitised fluorescent OLEDs. Herein we comprehensively review organoboron-based MR emitters based on their synthetic strategies, clarify structure-photophysical property correlations, and provide design guidelines and future development prospects.
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Affiliation(s)
- Masashi Mamada
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Masahiro Hayakawa
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Junki Ochi
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Takuji Hatakeyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
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6
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do Casal MT, Veys K, Bousquet MHE, Escudero D, Jacquemin D. First-Principles Calculations of Excited-State Decay Rate Constants in Organic Fluorophores. J Phys Chem A 2023; 127:10033-10053. [PMID: 37988002 DOI: 10.1021/acs.jpca.3c06191] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
In this Perspective, we discuss recent advances made to evaluate from first-principles the excited-state decay rate constants of organic fluorophores, focusing on the so-called static strategy. In this strategy, one essentially takes advantage of Fermi's golden rule (FGR) to evaluate rate constants at key points of the potential energy surfaces, a procedure that can be refined in a variety of ways. In this way, the radiative rate constant can be straightforwardly obtained by integrating the fluorescence line shape, itself determined from vibronic calculations. Likewise, FGR allows for a consistent calculation of the internal conversion (related to the non-adiabatic couplings) in the weak-coupling regime and intersystem crossing rates, therefore giving access to estimates of the emission yields when no complex photophysical phenomenon is at play. Beyond outlining the underlying theories, we summarize here the results of benchmarks performed for various types of rates, highlighting that both the quality of the vibronic calculations and the accuracy of the relative energies are crucial to reaching semiquantitative estimates. Finally, we illustrate the successes and challenges in determining the fluorescence quantum yields using a series of organic fluorophores.
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Affiliation(s)
- Mariana T do Casal
- Department of Chemistry, Physical Chemistry and Quantum Chemistry Division, KU Leuven, 3001 Leuven, Belgium
| | - Koen Veys
- Department of Chemistry, Physical Chemistry and Quantum Chemistry Division, KU Leuven, 3001 Leuven, Belgium
| | | | - Daniel Escudero
- Department of Chemistry, Physical Chemistry and Quantum Chemistry Division, KU Leuven, 3001 Leuven, Belgium
| | - Denis Jacquemin
- Nantes Université, CNRS, CEISAM UMR 6230, F-44000 Nantes, France
- Institut Universitaire de France (IUF), FR-75005 Paris, France
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7
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Chen G, Swartzfager JR, Asbury JB. Matrix Dynamics and Their Crucial Role in Non-radiative Decay during Thermally Activated Delayed Fluorescence. J Am Chem Soc 2023; 145:25495-25504. [PMID: 37955854 DOI: 10.1021/jacs.3c11719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
We investigated the interplay of matrix dynamics with the molecular dynamics of a thermally activated delayed fluorescence (TADF) emitter, NAI-DMAC, to identify factors that influence the photophysical processes leading to TADF. The matrix dynamics surrounding NAI-DMAC molecules were varied continuously from the liquid to the solid state by depositing toluene solutions containing poly(methyl methacrylate) (PMMA) and NAI-DMAC onto optical substrates. We monitored changes of the NAI-DMAC emission as the liquid films dried to form solid PMMA films using temperature- and time-resolved photoluminescence spectroscopy. We observed that, in low-viscosity solutions, the proportion of delayed fluorescence from NAI-DMAC was much smaller than that of prompt fluorescence, indicating that negligible TADF occurred in the low-viscosity environment. However, as the viscosity of the environment diverged at the final stages of dry-down to form solid PMMA films, the delayed fluorescence component of NAI-DMAC emission was extended to longer time scales and increased in amplitude relative to prompt emission as the temperature increased─signatures that TADF occurred in the solid state as expected. Our findings reveal the influence that matrix dynamics have on the competition between conformational motion needed to access emissive states and undergo TADF versus larger amplitude structural fluctuations that lead to non-radiative decay. Insights from these studies will inform ongoing work to understand and predict how host matrices used in organic light-emitting devices can be designed to maximize the radiative properties of TADF emitters by allowing molecular motion needed to undergo TADF while restricting larger amplitude motion leading to non-radiative decay.
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Affiliation(s)
- Gary Chen
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - John R Swartzfager
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - John B Asbury
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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8
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Gemen J, Church JR, Ruoko TP, Durandin N, Białek MJ, Weißenfels M, Feller M, Kazes M, Odaybat M, Borin VA, Kalepu R, Diskin-Posner Y, Oron D, Fuchter MJ, Priimagi A, Schapiro I, Klajn R. Disequilibrating azobenzenes by visible-light sensitization under confinement. Science 2023; 381:1357-1363. [PMID: 37733864 DOI: 10.1126/science.adh9059] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 08/22/2023] [Indexed: 09/23/2023]
Abstract
Photoisomerization of azobenzenes from their stable E isomer to the metastable Z state is the basis of numerous applications of these molecules. However, this reaction typically requires ultraviolet light, which limits applicability. In this study, we introduce disequilibration by sensitization under confinement (DESC), a supramolecular approach to induce the E-to-Z isomerization by using light of a desired color, including red. DESC relies on a combination of a macrocyclic host and a photosensitizer, which act together to selectively bind and sensitize E-azobenzenes for isomerization. The Z isomer lacks strong affinity for and is expelled from the host, which can then convert additional E-azobenzenes to the Z state. In this way, the host-photosensitizer complex converts photon energy into chemical energy in the form of out-of-equilibrium photostationary states, including ones that cannot be accessed through direct photoexcitation.
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Affiliation(s)
- Julius Gemen
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Jonathan R Church
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Tero-Petri Ruoko
- Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, 33101 Tampere, Finland
| | - Nikita Durandin
- Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, 33101 Tampere, Finland
| | - Michał J Białek
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50383 Wrocław, Poland
| | - Maren Weißenfels
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Moran Feller
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Miri Kazes
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Magdalena Odaybat
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, 82 Wood Lane, London W12 7SL, UK
| | - Veniamin A Borin
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Rishir Kalepu
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yael Diskin-Posner
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Dan Oron
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Matthew J Fuchter
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, 82 Wood Lane, London W12 7SL, UK
| | - Arri Priimagi
- Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 541, 33101 Tampere, Finland
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Rafal Klajn
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
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9
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Wu Z, Zhang Q, Wang X, Zhang K, Li X, Li R, Song Y, Fan J, Wang CK, Lin L, Wang Z. Multi-resonance thermally activated delayed fluorescence molecules with intramolecular-lock: theoretical design and performance prediction. Phys Chem Chem Phys 2023; 25:24406-24416. [PMID: 37621260 DOI: 10.1039/d3cp02255b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Multi-resonance thermally activated delayed fluorescence (MR-TADF) molecules with narrow full width at half maximum (FWHM) have attracted much attention recently. In this work, 36 borane/amine (B/N) type MR-TADF molecules were theoretically designed by using an intramolecular-lock strategy and systematically studied based on first-principles calculations. It was found that intramolecular-lock at different positions and in different manners could induce different luminescent properties. The calculated oscillator strengths for PXZ-L2 and PTZ-L2 locking systems are weaker than that for 2DPABN (without intramolecular-lock), while the Cz-L1 and TMCZ-L1 locking could result in stronger oscillator strength. Though the calculated FWHM of all the systems with intramolecular-lock is higher than that of 2DPABN, the Cz, TMCz and DMAC locking at L1 or L2 would induce relatively small FWHM which is comparable to that of 2DPABN. Our calculation results indicate that intramolecular-lock could enhance the SOC values and decrease the energy gap between the first singlet excited state and the first triplet excited state, which is quite favorable to reverse intersystem crossing. The Cz, TMCz and DMAC locking systems could realize comparable and higher efficiency than 2DPABN, thus higher quantum efficiency could be obtained. Our calculation results indicate that the intramolecular-lock strategy is an effective method to realize the design of highly efficient MR-TADF emitters.
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Affiliation(s)
- Zhimin Wu
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Qun Zhang
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Xiaofei Wang
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Kai Zhang
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Xiaofang Li
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Rui Li
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Yuzhi Song
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Jianzhong Fan
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Chuan-Kui Wang
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Lili Lin
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
| | - Zhongjie Wang
- Shandong Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
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10
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Omar Ö, Xie X, Troisi A, Padula D. Identification of Unknown Inverted Singlet-Triplet Cores by High-Throughput Virtual Screening. J Am Chem Soc 2023; 145:19790-19799. [PMID: 37639703 PMCID: PMC10510316 DOI: 10.1021/jacs.3c05452] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Indexed: 08/31/2023]
Abstract
Molecules where the energy of the lowest excited singlet state is found below the energy of the lowest triplet state (inverted singlet-triplet molecules) are extremely rare. It is particularly challenging to discover new ones through virtual screening because the required wavefunction-based methods are expensive and unsuitable for high-throughput calculations. Here, we devised a virtual screening approach where the molecules to be considered with advanced methods are pre-selected with increasingly more sophisticated filters that include the evaluation of the HOMO-LUMO exchange integral and approximate CASSCF calculations. A final set of 7 candidates (0.05% of the initial 15 000) were verified to possess inversion between singlet and triplet states with state-of-the-art multireference methods (MS-CASPT2). One of them is deemed of particular interest because it is unrelated to other proposals made in the literature.
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Affiliation(s)
- Ömer
H. Omar
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Xiaoyu Xie
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Alessandro Troisi
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Daniele Padula
- Dipartimento
di Biotecnologie, Chimica e Farmacia, Università
di Siena, Via A. Moro
2, Siena 53100, Italy
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11
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Xie X, Troisi A. Identification via Virtual Screening of Emissive Molecules with a Small Exciton-Vibration Coupling for High Color Purity and Potential Large Exciton Delocalization. J Phys Chem Lett 2023; 14:4119-4126. [PMID: 37129191 PMCID: PMC10165648 DOI: 10.1021/acs.jpclett.3c00749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A sequence of quantum chemical computations of increasing accuracy was used in this work to identify molecules with small exciton reorganization energy (exciton-vibration coupling), of interest for light emitting devices and coherent exciton transport, starting from a set of ∼4500 known molecules. We validated an approximate computational approach based on single-point calculations of the force in the excited state, which was shown to be very efficient in identifying the most promising candidates. We showed that a simple descriptor based on the bond order could be used to find molecules with potentially small exciton reorganization energies without performing excited state calculations. A small set of chemically diverse molecules with a small exciton reorganization energy was analyzed in greater detail to identify common features leading to this property. Many such molecules display an A-B-A structure where the bonding/antibonding patterns in the fragments A are similar in HOMO and LUMO. Another group of molecules with small reorganization energy displays instead HOMO and LUMO with a strong nonbonding character.
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Affiliation(s)
- Xiaoyu Xie
- Department of Chemistry, University of Liverpool Liverpool L69 3BX, U.K
| | - Alessandro Troisi
- Department of Chemistry, University of Liverpool Liverpool L69 3BX, U.K
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12
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Penfold TJ, Eng J. Mind the GAP: quantifying the breakdown of the linear vibronic coupling Hamiltonian. Phys Chem Chem Phys 2023; 25:7195-7204. [PMID: 36820783 DOI: 10.1039/d2cp05576g] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Excited state dynamics play a critical role across a broad range of scientific fields. Importantly, the highly non-equilibrium nature of the states generated by photoexcitation means that excited state simulations should usually include an accurate description of the coupled electronic-nuclear motion, which often requires solving the time-dependent Schrödinger equation (TDSE). One of the biggest challenges for these simulations is the requirement to calculate the PES over which the nuclei evolve. An effective approach for addressing this challenge is to use the approximate linear vibronic coupling (LVC) Hamiltonian, which enables a model potential to be parameterised using relatively few quantum chemistry calculations. However, this approach is only valid provided there are no large amplitude motions in the excited state dynamics. In this paper we introduce and deploy a metric, the global anharmonicity parameter (GAP), which can be used to assess the accuracy of an LVC potential. Following its derivation, we illustrate its utility by applying it to three molecules exhibiting different rigidity in their excited states.
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Affiliation(s)
- Thomas J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Julien Eng
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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13
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Lüdtke N, Steffen A, Marian CM. Finding Design Principles of OLED Emitters through Theoretical Investigations of Zn(II) Carbene Complexes. Inorg Chem 2022; 61:20896-20905. [PMID: 36490354 DOI: 10.1021/acs.inorgchem.2c03301] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this work, Zn(II) carbene complexes carrying a dianionic 1,2-dithiolbenzene (dtb) or 1,2-diolbenzene (dob) ligand were investigated regarding their suitability as organic light-emitting diode (OLED) emitter. For the optimization of the complexes, density functional-based methods were used and frequency analyses verified the obtained structures as minima. All calculations were carried out including a polarizable continuum model to mimic solvent-solute interactions. Multireference configuration interaction methods were used to determine excitation energies, spin-orbit couplings, and luminescence properties. Rate constants of spin-allowed and spin-forbidden transitions were calculated according to a Fermi golden rule expression. Using carbene ligands with varying σ-donor and π-acceptor strengths, the luminescence is found to be tunable from yellow to orange/red to deep red/near-infrared. The calculated intersystem crossing (ISC) time constants indicate thermally activated delayed fluorescence (TADF) to be the main decay channel. In contrast to many d10 coinage metal complexes, a parallel orientation of dtb or dob and the carbene ligand is found to be highly favorable. For the complexes with a cyclic (alkyl)(amino) carbene (CAAC) or cyclic (amino)(aryl) carbene (CAArC) ligand, the S1 and T1 states have ligand-to-ligand charge-transfer (LLCT) character and are energetically close. The complex with a classical N-heterocyclic carbene (NHC) ligand has S1 and T1 states with mixed ligand-to-metal charge-transfer (LMCT)/LLCT character and is a very rare example in which the zinc ion contributes to the excitation.
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Affiliation(s)
- Nora Lüdtke
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Andreas Steffen
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Str. 6, D-44227 Dortmund, Germany
| | - Christel M Marian
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
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14
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Ito A, Iwamura M, Sakuda E. Excited-state dynamics of luminescent transition metal complexes with metallophilic and donor–acceptor interactions. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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Cappello D, Buguis FL, Boyle PD, Gilroy JB. Dual Emission, Aggregation, and Redox Properties of Boron Difluoride Hydrazones Functionalized with Triphenylamines. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202200131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Daniela Cappello
- The University of Western Ontario Department of Chemistry CANADA
| | | | - Paul D. Boyle
- The University of Western Ontario Department of Chemistry CANADA
| | - Joe B. Gilroy
- The University of Western Ontario Department of Chemistry 1151 Richmond St. N. N6A 5B7 London CANADA
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16
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Cheon HJ, Shin YS, Park NH, Lee JH, Kim YH. Boron-Based Multi-Resonance TADF Emitter with Suppressed Intermolecular Interaction and Isomer Formation for Efficient Pure Blue OLEDs. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2107574. [PMID: 35274463 DOI: 10.1002/smll.202107574] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/03/2022] [Indexed: 06/14/2023]
Abstract
Multi-resonance (MR) thermally activated delayed fluorescent (TADF) emitters are highly attractive due to their superior color purity as well as efficient light-harvesting ability from singlets and triplets. However, boron and nitrogen-based MR-TADF emitters suffer from their strong π-π interaction owing to their rigid flat cores. Herein, a boron-based multi-resonance blue TADF emitter with suppressed intermolecular interaction and isomer formation is developed through a simple synthetic process by introducing meta-xylene and meta-phenyphenyl groups to the core. The MR-TADF emitter, mBP-DABNA-Me, shows a narrowband blue emission with a peak at 467 nm, along with full width at half maximum of 28 nm, and photoluminescence quantum yield of 97%. Notably, highly efficient pure blue organic light-emitting diode (OLED) is realized using mBP-DABNA-Me, showing a maximum external quantum efficiency of 24.3% and a stable blue emission with a Commission Internationale de L'Eclairage coordinate of (0.124, 0.140). The color purity of the OLED is maintained at a high doping concentration of over 20%, attributed to the suppressed intermolecular interaction between the MR emitters.
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Affiliation(s)
- Hyung Jin Cheon
- Department of Chemistry and RIGET, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Youn-Seob Shin
- Department of Materials Science and Engineering, Inha University, Incheon, 22212, Republic of Korea
| | - Noh-Hwal Park
- 3D Convergence Center, Inha University, Incheon, 22212, Republic of Korea
| | - Jeong-Hwan Lee
- Department of Materials Science and Engineering, Inha University, Incheon, 22212, Republic of Korea
- 3D Convergence Center, Inha University, Incheon, 22212, Republic of Korea
| | - Yun-Hi Kim
- Department of Chemistry and RIGET, Gyeongsang National University, Jinju, 52828, Republic of Korea
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17
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Ivanova G, Bozova N, Petkov N, An C, Hu B, Mutovska M, Konstantinov K, Zagranyarski Y, Videva V, Yordanova A, Baumgarten M, Ivanova A. Benchmarking of Density Functionals for the Description of Optical Properties of Newly Synthesized π-Conjugated TADF Blue Emitters. Chemistry 2022; 28:e202104411. [PMID: 35107870 DOI: 10.1002/chem.202104411] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Indexed: 11/10/2022]
Abstract
Computational modeling of the optical characteristics of organic molecules with potential for thermally activated delayed fluorescence (TADF) may assist markedly the development of more efficient emitting materials for organic light-emitting diodes. Recent theoretical studies in this area employ mostly methods from density functional theory (DFT). In order to obtain accurate predictions within this approach, the choice of a proper functional is crucial. In the current study, we focus on testing the performance of a set of DFT functionals for estimation of the excitation and emission energy and the excited singlet-triplet energy gap of three newly synthesized compounds with capacity for TADF. The emitters are designed specifically to enable charge transfer by π-electron conjugation, at the same time possessing high-energy excited triplet states. The functionals chosen for testing are from various groups ranging from gradient-corrected through global hybrids to range-separated ones. The results show that the monitored optical properties are especially sensitive to how the long-range part of the exchange energy is treated within the functional. The accurate functional should also be able to provide well balanced distribution of the π-electrons among the molecular fragments. Global hybrids with moderate (less than 0.4) share of exact exchange (B3LYP, PBE0) and the meta-GGA HSE06 are outlined as the best performing methods for the systems under study. They can predict all important optical parameters correctly, both qualitatively and quantitatively.
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Affiliation(s)
- Georgia Ivanova
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria
| | - Nadezhda Bozova
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria
| | - Nikolay Petkov
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria
| | - Cunbin An
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Benlin Hu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Monika Mutovska
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria
| | - Konstantin Konstantinov
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria
| | - Yulian Zagranyarski
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria
| | - Vladimira Videva
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria.,Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
| | - Adelina Yordanova
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria
| | - Martin Baumgarten
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Anela Ivanova
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164, Sofia, Bulgaria
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18
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Gribanov PS, Vorobyeva DV, Tokarev SD, Petropavlovskikh DA, Loginov DA, Nefedov SE, Dolgushin FM, Osipov SN. Rhodium‐Catalyzed C‐H Activation/Annulation of Aryl Hydroxamates with Benzothiadiazol‐Containing Acetylenes. Access to Isoquinoline‐Bridged Donor‐Acceptor Luminophores. European J Org Chem 2022. [DOI: 10.1002/ejoc.202101572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Pavel S. Gribanov
- A N Nesmeyanov Institute of Organoelement Compounds RAS: Institut elementoorganiceskih soedinenij imeni A N Nesmeanova RAN Organic Chemistry RUSSIAN FEDERATION
| | - Daria V. Vorobyeva
- A N Nesmeyanov Institute of Organoelement Compounds RAS: Institut elementoorganiceskih soedinenij imeni A N Nesmeanova RAN Organic Chemistry RUSSIAN FEDERATION
| | - Sergey D. Tokarev
- A N Nesmeyanov Institute of Organoelement Compounds RAS: Institut elementoorganiceskih soedinenij imeni A N Nesmeanova RAN Organic Chemistry RUSSIAN FEDERATION
| | - Dmitry A. Petropavlovskikh
- A N Nesmeyanov Institute of Organoelement Compounds RAS: Institut elementoorganiceskih soedinenij imeni A N Nesmeanova RAN Organic Chemistry RUSSIAN FEDERATION
| | - Dmitry A. Loginov
- A N Nesmeyanov Institute of Organoelement Compounds RAS: Institut elementoorganiceskih soedinenij imeni A N Nesmeanova RAN Organometallic Chemistry RUSSIAN FEDERATION
| | - Sergey E. Nefedov
- Kurnakov Institute of General and Inorganic Chemistry RAS: Institut obsej i neorganiceskoj himii imeni N S Kurnakova RAN X-ray RUSSIAN FEDERATION
| | - Fedor M. Dolgushin
- Kurnakov Institute of General and Inorganic Chemistry RAS: Institut obsej i neorganiceskoj himii imeni N S Kurnakova RAN X-ray RUSSIAN FEDERATION
| | - Sergey N. Osipov
- A.N. Nesmeyanov Institute of organoelement compounds, Russian Academy of Sciences Ecological Chemistry Vavilov28 119991 Moscow RUSSIAN FEDERATION
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19
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Omist A, Ricci G, Derradji A, Pérez-Jiménez AJ, San-Fabián E, Olivier Y, Sancho-García JC. peri-Acenoacene molecules: tuning of the singlet and triplet excitation energies by modifying their radical character. Phys Chem Chem Phys 2021; 23:24016-24028. [PMID: 34664570 DOI: 10.1039/d1cp03232a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The energy difference between singlet and triplet excitons, or ΔEST, is a key parameter for novel light-emission mechanisms (i.e., TADF or thermally activated delayed fluorescence) or other photoactivated processes. We have studied a set of conjugated molecules (peri-acenoacenes and their heteroatom-doped analogues) to observe the evolution of their excited-state properties upon increasing the system size with and without substitution with a pair of N atoms. Since these molecules exhibit a (ground-state) diradicaloid character, together with marked correlation effects influencing the excited-states formed, we have applied a variety of theoretical methods (FT-DFT, TD-DFT, SF-TD-DFT, CIS, CIS(D), SCS-CC2, SA-CASSCF, and SC-NEVPT2) to bracket the accuracy of the results while concomitantly providing insights into electronic structure. The results show how this chemical strategy (N-doping) largely modifies not only the excited-state energies but also the oscillator strengths and the ΔEST values, constituting versatile platforms for fine-tuned photophysical applications.
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Affiliation(s)
- A Omist
- Department of Physical Chemistry, University of Alicante, E-03080 Alicante, Spain.
| | - G Ricci
- Unité de Chimie Physique Théorique et Structurale & Laboratoire de Physique du Solid, Namur Institute of Structured Matter, Université de Namur, B-5000 Namur, Belgium
| | - A Derradji
- Department of Physical Chemistry, University of Alicante, E-03080 Alicante, Spain.
| | - A J Pérez-Jiménez
- Department of Physical Chemistry, University of Alicante, E-03080 Alicante, Spain.
| | - E San-Fabián
- Department of Physical Chemistry, University of Alicante, E-03080 Alicante, Spain.
| | - Y Olivier
- Unité de Chimie Physique Théorique et Structurale & Laboratoire de Physique du Solid, Namur Institute of Structured Matter, Université de Namur, B-5000 Namur, Belgium
| | - J C Sancho-García
- Department of Physical Chemistry, University of Alicante, E-03080 Alicante, Spain.
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20
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Zhang K, Fan J, Wang CK, Lin L. Highly efficient T-shaped deep-red thermally activated delayed fluorescence emitters: substitution position effect. Phys Chem Chem Phys 2021; 23:21883-21892. [PMID: 34558587 DOI: 10.1039/d1cp03144a] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Modulating the relationship between molecular structures and luminescence properties as well as charge transfer properties of deep-red thermally activated delayed fluorescence (TADF) emitters has always been a great challenge, especially in the solid state. In this work, the light-emitting properties of a T-shaped molecule (pTPA-DPPZ) with donors at the para-position are theoretically investigated in the solid state with the combined quantum mechanics/molecular mechanics (QM/MM) method and the thermal vibration correlation function (TVCF) theory. In comparison with a Y-shaped molecule (oTPA-DPPZ with donors at the ortho-position), pTPA-DPPZ acquires a reduced HOMO-LUMO energy gap and red-shifted emission. In addition, it is found that the transition dipole moment is enhanced and the radiative rate is increased. The stacking pattern of pTPA-DPPZ can effectively suppress the out-of-plane wagging vibration of donors, leading to the reduction of reorganization energy and inhibiting the loss of non-radiative energy in the excited state compared with oTPA-DPPZ. Besides, a larger spin-orbit coupling constant and a smaller energy gap between T2 and S1 (ΔET2-S1 = 0.1 eV) are found in pTPA-DPPZ, and thus a superior TADF emission is obtained. Moreover, the charge transport properties are studied using kinetic Monte Carlo simulations. The calculated mobilities for the electrons and holes of pTPA-DPPZ are all larger than those of oTPA-DPPZ, which is due to close packing modes in the pTPA-DPPZ crystal. Balanced charge transport properties are found, which is helpful for generation of excitons and light emission. The calculation results shed light on the relationship between the molecular structures and light-emitting properties of TADF emitters, which would be helpful for developing efficient non-doped deep-red TADF devices by using T-shaped molecular design.
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Affiliation(s)
- Kai Zhang
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, 250014 Jinan, China.
| | - Jianzhong Fan
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, 250014 Jinan, China.
| | - Chuan-Kui Wang
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, 250014 Jinan, China.
| | - Lili Lin
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, 250014 Jinan, China.
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21
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Zhao R, Hettich CP, Chen X, Gao J. Minimal-active-space multistate density functional theory for excitation energy involving local and charge transfer states. NPJ COMPUTATIONAL MATERIALS 2021; 7:148. [PMID: 36713117 PMCID: PMC9881008 DOI: 10.1038/s41524-021-00624-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 08/19/2021] [Indexed: 06/15/2023]
Abstract
Multistate density functional theory (MSDFT) employing a minimum active space (MAS) is presented to determine charge transfer (CT) and local excited states of bimolecular complexes. MSDFT is a hybrid wave function theory (WFT) and density functional theory, in which dynamic correlation is first incorporated in individual determinant configurations using a Kohn-Sham exchange-correlation functional. Then, nonorthogonal configuration-state interaction is performed to treat static correlation. Because molecular orbitals are optimized separately for each determinant by including Kohn-Sham dynamic correlation, a minimal number of configurations in the active space, essential to representing low-lying excited and CT states of interest, is sufficient to yield the adiabatic states. We found that the present MAS-MSDFT method provides a good description of covalent and CT excited states in comparison with experiments and high-level computational results. Because of the simplicity and interpretive capability through diabatic configuration weights, the method may be useful in dynamic simulations of CT and nonadiabatic processes.
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Affiliation(s)
- Ruoqi Zhao
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen 518055, China
- Institute of Theoretical Chemistry, Jilin University, Changchun, Jilin Province 130023, China
| | - Christian P. Hettich
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Xin Chen
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen 518055, China
- Beijing University Shenzhen Graduate School, Shenzhen 518055, China
| | - Jiali Gao
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen 518055, China
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
- Beijing University Shenzhen Graduate School, Shenzhen 518055, China
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22
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Drummond BH, Aizawa N, Zhang Y, Myers WK, Xiong Y, Cooper MW, Barlow S, Gu Q, Weiss LR, Gillett AJ, Credgington D, Pu YJ, Marder SR, Evans EW. Electron spin resonance resolves intermediate triplet states in delayed fluorescence. Nat Commun 2021; 12:4532. [PMID: 34312394 PMCID: PMC8313702 DOI: 10.1038/s41467-021-24612-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 06/22/2021] [Indexed: 11/09/2022] Open
Abstract
Molecular organic fluorophores are currently used in organic light-emitting diodes, though non-emissive triplet excitons generated in devices incorporating conventional fluorophores limit the efficiency. This limit can be overcome in materials that have intramolecular charge-transfer excitonic states and associated small singlet-triplet energy separations; triplets can then be converted to emissive singlet excitons resulting in efficient delayed fluorescence. However, the mechanistic details of the spin interconversion have not yet been fully resolved. We report transient electron spin resonance studies that allow direct probing of the spin conversion in a series of delayed fluorescence fluorophores with varying energy gaps between local excitation and charge-transfer triplet states. The observation of distinct triplet signals, unusual in transient electron spin resonance, suggests that multiple triplet states mediate the photophysics for efficient light emission in delayed fluorescence emitters. We reveal that as the energy separation between local excitation and charge-transfer triplet states decreases, spin interconversion changes from a direct, singlet-triplet mechanism to an indirect mechanism involving intermediate states.
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Affiliation(s)
- Bluebell H Drummond
- Department of Physics, Cavendish Laboratory, J J Thomson Avenue, University of Cambridge, Cambridge, UK
- Centre for Advanced Electron Spin Resonance (CAESR), Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford, UK
| | - Naoya Aizawa
- RIKEN Center for Emergent Matter Science (CEMS), Saitama, Japan
| | - Yadong Zhang
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, USA
| | - William K Myers
- Centre for Advanced Electron Spin Resonance (CAESR), Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford, UK
| | - Yao Xiong
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Matthew W Cooper
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Stephen Barlow
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Qinying Gu
- Department of Physics, Cavendish Laboratory, J J Thomson Avenue, University of Cambridge, Cambridge, UK
| | - Leah R Weiss
- Department of Physics, Cavendish Laboratory, J J Thomson Avenue, University of Cambridge, Cambridge, UK
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, USA
| | - Alexander J Gillett
- Department of Physics, Cavendish Laboratory, J J Thomson Avenue, University of Cambridge, Cambridge, UK
| | - Dan Credgington
- Department of Physics, Cavendish Laboratory, J J Thomson Avenue, University of Cambridge, Cambridge, UK
| | - Yong-Jin Pu
- RIKEN Center for Emergent Matter Science (CEMS), Saitama, Japan
| | - Seth R Marder
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Emrys W Evans
- Department of Physics, Cavendish Laboratory, J J Thomson Avenue, University of Cambridge, Cambridge, UK.
- Department of Chemistry, Swansea University, Swansea, UK.
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23
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Bertling J, Thom KA, Geenen S, Jeuken H, Presser L, Müller TJJ, Gilch P. Synthesis and Photophysics of Water-Soluble Psoralens with Red-Shifted Absorption. Photochem Photobiol 2021; 97:1534-1547. [PMID: 34181757 DOI: 10.1111/php.13480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/24/2021] [Indexed: 11/26/2022]
Abstract
8-Methoxypsoralen (8-MOP) serves as a PUVA (psoralen + UV-A) agent in the treatment of certain skin diseases. Derivatives of 8-MOP with cationic aromatic substituents at the five positions were synthesized and characterized by steady-state, femtosecond and nanosecond spectroscopy as well as cyclic voltammetry. The aromatic substituents' positive charge increases the water solubility and the affinity toward intercalation into DNA. The aromatic substituents were supposed to lower the psoralen S1 energy and thereby suppress a photo-induced electron transfer (PET) with guanine-bearing DNA. Such a suppression of this PET is expected to increase the propensity of psoralens to photo-addition to DNA. For derivatives bearing methylpyridinium residues, femtosecond spectroscopy revealed an intramolecular PET occurring on the picosecond time scale. This PET precludes the population of the triplet state. As triplet states are the precursor state for the photo-addition to DNA, their intermolecular PET renders these derivatives ineffective in terms of PUVA. For two derivatives bearing trimethylphenylammonium moieties, such an intramolecular PET does not occur and the triplet state is populated. Surprisingly, these compounds also exhibit no PUVA activity. Based on these findings, implications for further optimization of PUVA agents are discussed.
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Affiliation(s)
- Janina Bertling
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Kristoffer A Thom
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Sarah Geenen
- Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Hannah Jeuken
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Lysander Presser
- Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Thomas J J Müller
- Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Peter Gilch
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
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24
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Thom KA, Wieser F, Diestelhorst K, Reiffers A, Czekelius C, Kleinschmidt M, Bracker M, Marian CM, Gilch P. Acridones: Strongly Emissive HIGHrISC Fluorophores. J Phys Chem Lett 2021; 12:5703-5709. [PMID: 34125550 DOI: 10.1021/acs.jpclett.1c01381] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
An acridone derivative (N-methyl-difluoro-acridone, NMA-dF) is characterized with respect to its utility as an emitter in organic light emitting diodes (OLEDs). Using steady-state and time-resolved spectroscopy as well as quantum chemistry, its ability to convert singlet and triplet excitons into light was scrutinized. NMA-dF emits in the deep blue range of the visible spectrum. Its fluorescence emission occurs with quantum yields close to 1 and a radiative rate constant of ≈5 × 108 s-1. So, it processes singlet excitons very efficiently. Using 1,4-dichlorobenzene as a sensitizer, it is shown that NMA-dF also converts triplet excitons into light. With the aid of quantum chemistry, this is related to a reverse intersystem crossing starting from a higher triplet state (HIGHrISC).
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Affiliation(s)
- Kristoffer A Thom
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Felix Wieser
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Kevin Diestelhorst
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Anna Reiffers
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Constantin Czekelius
- Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Martin Kleinschmidt
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Mario Bracker
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Christel M Marian
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Peter Gilch
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
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P∩N Bridged Cu(I) Dimers Featuring Both TADF and Phosphorescence. From Overview towards Detailed Case Study of the Excited Singlet and Triplet States. Molecules 2021; 26:molecules26113415. [PMID: 34200044 PMCID: PMC8200198 DOI: 10.3390/molecules26113415] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 05/23/2021] [Accepted: 05/25/2021] [Indexed: 11/16/2022] Open
Abstract
We present an overview over eight brightly luminescent Cu(I) dimers of the type Cu2X2(P∩N)3 with X = Cl, Br, I and P∩N = 2-diphenylphosphino-pyridine (Ph2Ppy), 2-diphenylphosphino-pyrimidine (Ph2Ppym), 1-diphenylphosphino-isoquinoline (Ph2Piqn) including three new crystal structures (Cu2Br2(Ph2Ppy)3 1-Br, Cu2I2(Ph2Ppym)3 2-I and Cu2I2(Ph2Piqn)3 3-I). However, we mainly focus on their photo-luminescence properties. All compounds exhibit combined thermally activated delayed fluorescence (TADF) and phosphorescence at ambient temperature. Emission color, decay time and quantum yield vary over large ranges. For deeper characterization, we select Cu2I2(Ph2Ppy)3, 1-I, showing a quantum yield of 81%. DFT and SOC-TDDFT calculations provide insight into the electronic structures of the singlet S1 and triplet T1 states. Both stem from metal+iodide-to-ligand charge transfer transitions. Evaluation of the emission decay dynamics, measured from 1.2 ≤ T ≤ 300 K, gives ∆E(S1-T1) = 380 cm−1 (47 meV), a transition rate of k(S1→S0) = 2.25 × 106 s−1 (445 ns), T1 zero-field splittings, transition rates from the triplet substates and spin-lattice relaxation times. We also discuss the interplay of S1-TADF and T1-phosphorescence. The combined emission paths shorten the overall decay time. For OLED applications, utilization of both singlet and triplet harvesting can be highly favorable for improvement of the device performance.
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Abstract
This review article focuses on the understanding of intersystem crossing (ISC) in molecules. It addresses readers who are interested in the phenomenon of intercombination transitions between states of different electron spin multiplicities but are not familiar with relativistic quantum chemistry. Among the spin-dependent interaction terms that enable a crossover between states of different electron spin multiplicities, spin-orbit coupling (SOC) is by far the most important. If SOC is small or vanishes by symmetry, ISC can proceed by electronic spin-spin coupling (SSC) or hyperfine interaction (HFI). Although this review discusses SSC- and HFI-based ISC, the emphasis is on SOC-based ISC. In addition to laying the theoretical foundations for the understanding of ISC, the review elaborates on the qualitative rules for estimating transition probabilities. Research on the mechanisms of ISC has experienced a major revival in recent years owing to its importance in organic light-emitting diodes (OLEDs). Exemplified by challenging case studies, chemical substitution and solvent environment effects are discussed with the aim of helping the reader to understand and thereby get a handle on the factors that steer the efficiency of ISC.
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Affiliation(s)
- Christel M Marian
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University, Düsseldorf 40204, Germany;
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Lin S, Ou Q, Wang Y, Peng Q, Shuai Z. Aggregation-Enhanced Thermally Activated Delayed Fluorescence Efficiency for Two-Coordinate Carbene-Metal-Amide Complexes: A QM/MM Study. J Phys Chem Lett 2021; 12:2944-2953. [PMID: 33725452 DOI: 10.1021/acs.jpclett.1c00020] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The two-coordinate carbene-metal-amide complexes have attracted a great deal of attention due to their remarkable thermally activated delayed fluorescence (TADF) properties, giving them promise in organic light-emitting diode application. To reveal the inherent mechanism, we take CAAC-Cu(I)-Cz and CAAC-Au(I)-Cz as examples to investigate the photophysical properties in solution and solid phases by combining quantum mechanics/molecular mechanics approaches for the electronic structure and the thermal vibration correlation function formalism for the excited-state decay rates. We found that both intersystem crossing (ISC) and its reverse (rISC) are enhanced by 2-4 orders of magnitude upon aggregation, leading to highly efficient TADF, because (i) the metal proportion in the frontier molecular orbitals increases, leading to an enhanced spin-orbit coupling strength between S1 and T1, and (ii) the reaction barriers for ISC and rISC are much lower in solution than in aggregate phases through a decrease in energy gap ΔEST and an increase in the relative reorganization energy through bending the angle ∠C2-Cu-N1 for T1. We propose a pump-probe time-resolved infrared spectroscopy study to verify the mechanism. These findings can clarify the ongoing dispute over the understanding of the high TADF quantum efficiency for two-coordinate metal complexes.
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Affiliation(s)
- Shiyun Lin
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Qi Ou
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Yu Wang
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Qian Peng
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Zhigang Shuai
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
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Lüdtke N, Föller J, Marian CM. Understanding the luminescence properties of Cu(i) complexes: a quantum chemical perusal. Phys Chem Chem Phys 2020; 22:23530-23544. [PMID: 33074271 DOI: 10.1039/d0cp04654j] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Electronic structures and excited-state properties of Cu(i) complexes with varying coordination numbers have been investigated by means of advanced quantum chemical methods. The computational protocol employs density functional-based methods for geometry optimizations and vibrational analyses including solvent effects through continuum models. Excitation energies, spin-orbit couplings and luminescence properties are evaluated using multireference configuration interaction methods. Rate constants of spin-allowed and spin-forbidden transitions have been determined according to the Fermi golden rule. The computational results for the 4-coordinate (DPEPhos)Cu(PyrTet), the 3-coordinate [IPr-Cu-Py2]+, and the linear CAACMe2-Cu-Cl complexes agree well with experimental absorption and emission wavelengths, intersystem crossing (ISC) time constants, and radiative lifetimes in liquid solution. Spectral shifts on the ligand-to-ligand charge transfer (LLCT) and metal-to-ligand charge transfer (MLCT) transitions caused by the polarity of the environment are well represented by the continuum models whereas the shifts caused by pseudo-Jahn-Teller distortions in the MLCT states are too pronounced in comparison to solid-state data. Systematic variation of the ligands in linear Cu(i) carbene complexes shows that only those complexes with S1 and T1 states of LLCT character possess sufficiently small singlet-triplet energy gaps ΔEST to enable thermally activated delayed fluorescence (TADF). Complexes whose S1 and T1 wavefunctions are dominated by MLCT excitations tend to emit phosphorescence instead. Unlike the situation in metal-free TADF emitters, the presence of low-lying locally excited triplet states does not promote ISC. These states rather hold the danger of trapping the excitation with nonradiative deactivation being the major deactivation channel.
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Affiliation(s)
- Nora Lüdtke
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
| | - Jelena Föller
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
| | - Christel M Marian
- Institute of Theoretical and Computational Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
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