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Zhao J, Liu H, Fan J, Mu Q. A molecular descriptor of a shallow potential energy surface for the ground state to achieve narrowband thermally activated delayed fluorescence emission. Phys Chem Chem Phys 2024; 26:5156-5168. [PMID: 38260957 DOI: 10.1039/d3cp05875a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Narrowband thermally activated delayed fluorescence (TADF) molecules have extensive applications in optoelectronics, biomedicine, and energy. The full-width at half-maximum (FWHM) holds significant importance in assessing the luminescence efficiency and color purity of TADF molecules. The goal is to achieve efficient and stable TADF emissions by regulating and optimizing the FWHM. However, a bridge from the basic physical parameters (such as geometric structure and reorganization energy) to the macroscopic properties (delayed fluorescence, efficiency, and color purity) is needed and it is highly necessary and urgent to explore the internal mechanisms that influence FWHM. Herein, first-principles calculations coupled with the thermal vibration correlation function (TVCF) theory were performed to study the energy consumption processes of the excited states for the three TADF molecules (2,3-POA, 2,3-DPA, and 2,3-CZ) with different donors; inner physical parameters affecting the FWHM were detected. By analyzing the basic geometric and electronic structures as well as the transition properties and reorganization energies, three main findings in modulating FWHM were obtained, namely a large local excitation (LE) proportion in the first singlet excited state is advantageous in reducing FWHM, a donor group with weak electron-donating ability is beneficial for achieving narrowband emission, and small reorganization energies for the ground state are favorable for reducing FWHM. Thus, wise molecular design strategies to achieve efficient narrowband TADF emission are theoretically proven and proposed. We hope that these results will promote an in-depth understanding of FWHM and accelerate the development of high color purity TADF emitters.
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Affiliation(s)
- Jiaqiang Zhao
- School of Physics and Electronic Information, Weifang University, Weifang 261061, China.
| | - Huanling Liu
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
| | - Jianzhong Fan
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
| | - Qingfang Mu
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
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2
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Bardi B, Giavazzi D, Ferrari E, Iagatti A, Di Donato M, Phan Huu DKA, Di Maiolo F, Sissa C, Masino M, Lapini A, Painelli A. Solid state solvation: a fresh view. MATERIALS HORIZONS 2023; 10:4172-4182. [PMID: 37522331 DOI: 10.1039/d3mh00988b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
The design of efficient organic electronic devices, including OLEDs, OPVs, luminescent solar concentrators, etc., relies on the optimization of relevant materials, often constituted by an active (functional) dye embedded in a matrix. Understanding solid state solvation (SSS), i.e. how the properties of the active dye are affected by the matrix, is therefore an issue of fundamental and technological relevance. Here an extensive experimental and theoretical investigation is presented shedding light on this, somewhat controversial, topic. The spectral properties of the dye at equilibrium, i.e. absorption and Raman spectra, are not affected by the matrix dynamics. Reliable estimates of the matrix polarity are then obtained from an analysis of the micro-Raman spectra of polar dyes. Specifically, to establish a reliable polarity scale, the spectra of DCM or NR dispersed in amorphous matrices are compared with the spectra of the same dyes in liquid solvents with known polarity. On the other hand, steady-state emission spectra obtained in solid matrices depend in a highly non-trivial way on the matrix polarity and its dynamics. An extensive experimental and theoretical analysis of the time-resolved emission spectra of NR in a very large time window (15 fs-15 ns) allows us to validate this dye as a good probe of the dielectric dynamics of the surrounding medium. We provide a first assessment of the relaxation dynamics of two matrices (mCBPCN and DPEPO) of interest for OLED application, unambiguously demonstrating that the matrix readjusts for at least 15 ns after the dye photoexcitation.
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Affiliation(s)
- Brunella Bardi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Davide Giavazzi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Elena Ferrari
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Alessandro Iagatti
- CNR-INO (Istituto Nazionaledi Ottica), Largo Fermi 6, 50125 Firenze, Italy
- LENS (European Laboratory for Non-Linear Spectroscopy), Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
| | - Mariangela Di Donato
- LENS (European Laboratory for Non-Linear Spectroscopy), Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
- ICCOM-CNR, via Madonna del Piano 10, I-50019 Sesto Fiorentino, FI, Italy
| | - D K Andrea Phan Huu
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Francesco Di Maiolo
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Cristina Sissa
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Matteo Masino
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Andrea Lapini
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
- LENS (European Laboratory for Non-Linear Spectroscopy), Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
| | - Anna Painelli
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
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Madushani B, Mamada M, Goushi K, Nguyen TB, Nakanotani H, Kaji H, Adachi C. Multiple donor-acceptor design for highly luminescent and stable thermally activated delayed fluorescence emitters. Sci Rep 2023; 13:7644. [PMID: 37169821 PMCID: PMC10175249 DOI: 10.1038/s41598-023-34623-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 05/04/2023] [Indexed: 05/13/2023] Open
Abstract
A considerable variety of donor-acceptor (D-A) combinations offers the potential for realizing highly efficient thermally activated delayed fluorescence (TADF) materials. Multiple D-A type compounds are one of the promising families of TADF materials in terms of stability as well as efficiencies. However, those emitters are always composed of carbazole-based donors despite a wide choice of moieties used in linearly linked single D-A molecules. Herein, we developed a multiple D-A type TADF compound with two distinct donor units of 9,10-dihydro-9,9-dimethylacridine (DMAC) and carbazole as the hetero-donor design. The new emitter exhibits high photoluminescence quantum yield (PLQY) in various conditions including polar media blend and high concentrations. Organic light-emitting diodes (OLEDs) showed a reasonably high external quantum efficiency (EQE). In addition, we revealed that the multiple-D-A type molecules showed better photostability than the single D-A type molecules, while the operational stability in OLEDs involves dominant other factors.
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Affiliation(s)
- Bhagya Madushani
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Masashi Mamada
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Motooka, Nishi, Fukuoka, 819-0395, Japan.
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
| | - Kenichi Goushi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Thanh Ba Nguyen
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Hajime Nakanotani
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Hironori Kaji
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 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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Hempe M, Kukhta NA, Danos A, Batsanov AS, Monkman AP, Bryce MR. Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt? J Phys Chem Lett 2022; 13:8221-8227. [PMID: 36007139 PMCID: PMC9465681 DOI: 10.1021/acs.jpclett.2c00907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Intramolecular hydrogen bonding between donor and acceptor segments in thermally activated delayed fluorescence (TADF) materials is now frequently employed to─purportedly─rigidify the structure and improve the emission performance of these materials. However, direct evidence for these intramolecular interactions is often lacking or ambiguous, leading to assertions that are largely speculative. Here we investigate a series of TADF-active materials incorporating pyridine, which bestows the potential ability to form intramolecular H-bonding interactions. Despite possible indications of H-bonding from an X-ray analysis, an array of other experimental investigations proved largely inconclusive. Instead, after examining computational potential energy surfaces of the donor-acceptor torsion angle we conclude that the pyridine group primarily alleviates steric congestion in our case, rather than enabling an H-bond interaction as elsewhere assumed. We suggest that many previously reported "H-bonding" TADF materials featuring similar chemical motifs may instead operate similarly and that investigation of potential energy surfaces should become a key feature of future studies.
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Affiliation(s)
- Matthias Hempe
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Nadzeya A. Kukhta
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
- Materials
Science and Engineering Department, University
of Washington, Seattle, Washington 98195, United States
| | - Andrew Danos
- Physics
Department, Durham University, South Road, Durham, DH1 3LE, U.K.
| | - Andrei S. Batsanov
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrew P. Monkman
- Physics
Department, Durham University, South Road, Durham, DH1 3LE, U.K.
| | - Martin R. Bryce
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
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5
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Zhang K, Zhang X, Fan J, Song Y, Fan J, Wang CK, Lin L. Novel Deep Red Thermally Activated Delayed Fluorescence Molecule with Aggregation-Induced Emission Enhancement: Theoretical Design and Experimental Validation. J Phys Chem Lett 2022; 13:4711-4720. [PMID: 35611873 DOI: 10.1021/acs.jpclett.2c00779] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Thermally activated delayed fluorescence (TADF) molecules with deep red luminescence have shown great applications in organic light-emitting diodes (OLEDs). However, the development of high efficient deep red TADF emitters is full of resistance, and new design strategies are highly desired. This work theoretically predicts the luminescence properties and photophysical mechanism of a spiro-acridine based molecule DBPz-2spAc in toluene and aggregation states. Experiments further show that the solid state can effectively suppress nonradiative energy loss and thus improve luminescence efficiency. OLEDs based on DBPz-2spAc show high luminescence efficiency. In addition, studies based on spiro-acridine derivatives indicate that bending the degree of acridine in excited state will directly affect the nonradiative energy loss. This study improves the understanding of the luminous behavior of spiro-acridine derivative based TADF emitters in solution and in aggregation state, which should pave the way for the design of efficient deep red TADF materials.
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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
| | - Xiao Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, 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
| | - Yuzhi Song
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, 250014 Jinan, China
| | - Jian Fan
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, 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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6
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Francese T, Kundu A, Gygi F, Galli G. Quantum simulations of thermally activated delayed fluorescence in an all-organic emitter. Phys Chem Chem Phys 2022; 24:10101-10113. [PMID: 35416814 DOI: 10.1039/d2cp01147f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the prototypical NAI-DMAC thermally activated delayed fluorescence (TADF) emitter in the gas phase- and high-packing fraction limits at finite temperature, by combining first principles molecular dynamics with a quantum thermostat to account for nuclear quantum effects (NQE). We find a weak dependence of the singlet-triplet energy gap (ΔEST) on temperature in both the solid and the molecule, and a substantial effect of packing. While the ΔEST vanishes in the perfect crystal, it is of the order of ∼0.3 eV in the molecule, with fluctuations ranging from 0.1 to 0.4 eV at 300 K. The transition probability between the HOMOs and LUMOs has a stronger dependence on temperature than the singlet-triplet gap, with a desirable effect for thermally activated fluorescence; such temperature effect is weaker in the condensed phase than in the molecule. Our results on ΔEST and oscillator strengths, together with our estimates of direct and reverse intersystem crossing rates, show that optimization of packing and geometrical conformation is critical to increase the efficiency of TADF compounds. Our findings highlight the importance of considering thermal fluctuations and NQE to obtain robust predictions of the electronic properties of NAI-DMAC.
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Affiliation(s)
- Tommaso Francese
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
| | - Arpan Kundu
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
| | - Francois Gygi
- Department of Computer Science, University of California, Davis, CA 95616, USA
| | - Giulia Galli
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA. .,Materials Science Division and Center for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA.,Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
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7
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Sakamaki D, Tanaka S, Tanaka K, Takino M, Gon M, Tanaka K, Hirose T, Hirobe D, Yamamoto HM, Fujiwara H. Double Heterohelicenes Composed of Benzo[ b]- and Dibenzo[ b, i]phenoxazine: A Comprehensive Comparison of Their Electronic and Chiroptical Properties. J Phys Chem Lett 2021; 12:9283-9292. [PMID: 34542299 DOI: 10.1021/acs.jpclett.1c02896] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Heterohelicenes are potential materials in molecular electronics and optics because of their inherent chirality and various electronic properties originating from the introduced heteroatoms. In this work, we comprehensively investigated two kinds of double NO-hetero[5]helicenes composed of 12H-benzo[b]phenoxazine (BPO) and 13H-dibenzo[b,i]phenoxazine (DBPO). These helicenes exhibit good electron-donor properties reflecting the electron-rich character of their monomers and were demonstrated to work as p-type semiconductors. The enantiomers of these helicenes show the largest class of dissymmetry factors for circularly polarized luminescence (CPL) (|gCPL| > 10-2) among helicenes reported to date. Interestingly, the signs of CPL are opposite for BPO and DBPO double helicenes of the same helicity. The origin of the large gCPL values and the inversion of the CPL sign was addressed by analysis of the transition electronic dipole moments and transition magnetic dipole moments based on TD-DFT calculations.
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Affiliation(s)
- Daisuke Sakamaki
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Shunya Tanaka
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Katsuki Tanaka
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Mayu Takino
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Masayuki Gon
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kazuo Tanaka
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Takashi Hirose
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
| | - Daichi Hirobe
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
- SOKENDAI (Graduate University for Advanced Studies), Myodaiji, Okazaki 444-8585, Japan
| | - Hiroshi M Yamamoto
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
- SOKENDAI (Graduate University for Advanced Studies), Myodaiji, Okazaki 444-8585, Japan
| | - Hideki Fujiwara
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Naka-ku, Sakai, Osaka 599-8531, Japan
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