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Leonhardt C, Mauri A, Garin I, Rosemann NW, Wenzel W, Lemmer U, Kozlowska M, Bräse S. Tetrazole and Oxadiazole Derivatives as Thermally Activated Delayed Fluorescence Emitters. Chemistry 2024; 30:e202401682. [PMID: 38934566 DOI: 10.1002/chem.202401682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 06/12/2024] [Accepted: 06/25/2024] [Indexed: 06/28/2024]
Abstract
Organic light-emitting diodes (OLEDs) are promising lighting solutions for sustainability and energy efficiency. Incorporating thermally activated delayed fluorescence (TADF) molecules enables OLEDs to achieve internal quantum efficiency (IQE), in principle, up to 100 %; therefore, new classes of promising TADF emitters and modifications of existing ones are sought after. This study explores the TADF emission properties of six designed TADF emitters, examining their photophysical responses using experimental and theoretical methods. The design strategy involves creating six distinct types of a donor-acceptor (D-A) system, where tert-butylcarbazoles are used as donors, while the acceptor component incorporates three different functional groups: nitrile, tetrazole and oxadiazole, with varying electron-withdrawing character. Additionally, the donor-acceptor distance is adjusted using a phenylene spacer, and its influence on TADF functionality is examined. The clear dependency of an additional spacer, inhibiting TADF, could be revealed. Emitters with a direct donor-acceptor connection are demonstrated to exhibit TADF moderate emissive behavior. The analysis emphasizes the impact of charge transfer, singlet-triplet energy gaps (ΔEST), and other microscopic parameters on photophysical rates, permitting TADF. Among the emitters, TCz-CN shows optimal performance as a blue-green emitter with an 88 % photoluminescence quantum yield (PLQY) and fast rate of reversible intersystem crossing of 2×106 s-1 and 1×107 s-1, obtained from time-resolved photoluminescence (TRPL) experiment in PMMA matrix and quantum mechanical calculations, respectively. This comprehensive exploration identifies molecular bases of superior TADF emitters and provides insights for future designs, advancing the optimization of TADF properties in OLEDs.
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Affiliation(s)
- Céline Leonhardt
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
| | - Anna Mauri
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
| | - Idoia Garin
- Light Technology Institute, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
| | - Nils W Rosemann
- Light Technology Institute, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
| | - Wolfgang Wenzel
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
| | - Uli Lemmer
- Light Technology Institute, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
| | - Mariana Kozlowska
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
| | - Stefan Bräse
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
- Institute of Biological and Chemical Systems - IBCS-FMS, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131, Karlsruhe, Germany
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2
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dos Santos PL, de Sa Pereira D, Oh CS, Kukhta N, Lee HL, Lee JY, Monkman AP. Influence of Multiple rISC Channels on the Maximum Efficiency and Roll-Off of TADF OLEDs. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:16308-16319. [PMID: 39380972 PMCID: PMC11457217 DOI: 10.1021/acs.jpcc.4c02993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 09/03/2024] [Accepted: 09/04/2024] [Indexed: 10/10/2024]
Abstract
In this work, we look into the detailed photophysical characterization of a multidonor-acceptor (D-A) family of thermally activated delayed fluorescent (TADF) emitters to find correlations with their device performance. Increasing the number of closely packed Ds around the A core leads to changes in dihedral angles between Ds and A, affecting the highest occupied molecular orbital (HOMO)/lowest unpccupied molecualar orbital (LUMO) separation and impacting the singlet-triplet energy gaps. Moreover, D-A dihedral angles change molecular conjugation affecting the spread of charge-transfer state energies as well as the energy of D local triplet states. The coupling between these triplet states and the dispersion in CT states lead to the appearance of multiple rISC channels, a phenomenon that is host-dependent, i.e., hosts with different rigidities twist the dihedral angles differently. We show that different subsets of rISC rates directly impact device performance, where faster rISC leads to external quantum efficiencies above 20% while slower rISC rates act as parasitic traps, severely affecting device roll-off. This explains why emitters with excellent peak external quantum efficiencies can also present very poor roll-off.
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Affiliation(s)
- Paloma Lays dos Santos
- Department
of Electronic and Electrical Engineering, University of Sheffield, Mappin St, Sheffield S1
3JD, U.K.
| | | | - Chan Seok Oh
- School
of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi 16419, Korea
| | - Nadzeya Kukhta
- Department
of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Ha Lim Lee
- School
of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi 16419, Korea
| | - Jun Yeob Lee
- School
of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi 16419, Korea
- SKKU
Institute of Energy Science and Technology, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi 16419, Korea
| | - Andrew P. Monkman
- Department
of Physics, Durham University, South Road, Durham DH1 3LE, U.K.
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3
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Li P, Lai SL, Chen Z, Tang WK, Leung MY, Ng M, Kwok WK, Chan MY, Yam VWW. Achieving efficient and stable blue thermally activated delayed fluorescence organic light-emitting diodes based on four-coordinate fluoroboron emitters by simple substitution molecular engineering. Chem Sci 2024; 15:12606-12615. [PMID: 39118634 PMCID: PMC11304800 DOI: 10.1039/d3sc06989c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 06/18/2024] [Indexed: 08/10/2024] Open
Abstract
Achieving both high efficiency and high stability in blue thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) is challenging for practical displays and lighting. Here, we have successfully developed a series of sky-blue to pure-blue emitting donor-acceptor (D-A) type TADF materials featuring a four-coordinated boron with 2,2'-(pyridine-2,6-diyl)diphenolate (dppy) ligands, i.e.1-8. Synergistic engineering of substituents on the phenyl bridge as well as the electronic properties and the attached positions of heteroatom N-donors not only enables fine-tuning of the emission colors, but also modulates the nature and energies of their triplet excited states that are important for the reverse intersystem crossing (RISC). Particularly for the compound with two methyl substituents on the phenyl bridge (compound 8), RISC is significantly facilitated through the vibronic coupling of the energetically close-lying triplet charge transfer (3CT) and the triplet local excited (3LE) states, when compared to analogue 7. Efficient sky-blue to pure-blue OLEDs with electroluminescence peaks (λ EL) at 460-492 nm have been obtained, in which ca. five-fold higher external quantum efficiencies (EQEs) of 18.9% have been demonstrated by 8 than that by 7. Moreover, ca. thirty times longer device operational half-lifetimes (LT50) of 9113 hours for 8 than that for 7 as well as satisfactory LT50 reaching 26 643 hours for 6 at an initial luminance of 100 cd m-2 have also been demonstrated. To the best of our knowledge, these results represent one of the best high-performance blue OLEDs based on tetracoordinated boron TADF emitters. Moreover, the design strategy presented here has provided an attractive strategy for enhancing the device performance of blue TADF-OLEDs.
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Affiliation(s)
- Panpan Li
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
- Hong Kong Quantum AI Lab Limited 17 Science Park West Avenue Pak Shek Kok Hong Kong P. R. China
| | - Shiu-Lun Lai
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Ziyong Chen
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Wai Kit Tang
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Ming-Yi Leung
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
- Hong Kong Quantum AI Lab Limited 17 Science Park West Avenue Pak Shek Kok Hong Kong P. R. China
| | - Maggie Ng
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Wing-Kei Kwok
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
- Hong Kong Quantum AI Lab Limited 17 Science Park West Avenue Pak Shek Kok Hong Kong P. R. China
| | - Mei-Yee Chan
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
- Hong Kong Quantum AI Lab Limited 17 Science Park West Avenue Pak Shek Kok Hong Kong P. R. China
| | - Vivian Wing-Wah Yam
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
- Hong Kong Quantum AI Lab Limited 17 Science Park West Avenue Pak Shek Kok Hong Kong P. R. China
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Stanimirov S, Djumayska S, Todorova N, Mutovska M, Konstantinov K, Petrova P, Tomova R, Ivanov P, Ivanova G, Stoyanov S, Spassov T, Trifonov A, Buchvarov I, Baumgarten M, Ivanova A, Zagranyarski Y. TADF Blue Emitters with Balanced π-Conjugation─Design, Synthesis, Spectral Characterization, and a Model OLED with 8-(5-( tert-Butyl)-1,3,4-oxadiazol-2-yl)- N, N-bis(4-( tert-butyl)phenyl)dibenzo[ b, d]furan-2-amine. J Phys Chem A 2024; 128:5100-5114. [PMID: 38915245 DOI: 10.1021/acs.jpca.4c01371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Blue organic light-emitting diodes (OLED) suffer from relatively short lifetimes and a comparatively low lighting efficiency. One of the approaches to improving their characteristics is the development of luminophores with the potential for thermally activated delayed fluorescence (TADF). Herein, a set of donor-spacer-acceptor compounds with potential for TADF are designed, synthesized, and computationally and spectroscopically characterized. The excited state dynamics of the most prospective dye is monitored by time-resolved fluorescence and transient absorption spectroscopy. The experimental data are obtained and processed by a newly developed method and supplemented by quantum chemical calculations. The comprehensive approach allowed rationalization of the complex cascade-type photophysical behavior. The most promising emitter is included in an OLED displaying a blue color with a maximum EQE of 4.9% and negligible efficiency roll-off at higher luminance.
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Affiliation(s)
- Stanislav Stanimirov
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria
| | - Simona Djumayska
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria
| | - Neda Todorova
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria
| | - 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
| | - Petia Petrova
- Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, 1164 Sofia, Bulgaria
| | - Reni Tomova
- Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, 1164 Sofia, Bulgaria
| | - Petar Ivanov
- Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, 1164 Sofia, Bulgaria
| | - Georgia Ivanova
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria
| | - Stanimir Stoyanov
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria
| | - Tony Spassov
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria
| | - Anton Trifonov
- John Atanasoff Center for Bio and Nano Photonics (JAC BNP), 1164 Sofia, Bulgaria
| | - Ivan Buchvarov
- Physics Department, University of Sofia, 5 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
| | - Yulian Zagranyarski
- Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria
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5
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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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6
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Zhang S, Zhou Z, Qu Z. Diradical-Based Strategy in Designing Narrowband Thermally Activated Delayed Fluorescence Molecules with Tunable Emission Wavelengths. J Phys Chem Lett 2024:2723-2731. [PMID: 38437846 DOI: 10.1021/acs.jpclett.4c00146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
In the design of thermally activated delayed fluorescence (TADF) materials, narrow-band emission is of particular importance for the development of organic light-emitting diodes (OLEDs). In this work, we proposed a new strategy for designing TADF molecules utilizing degenerate nonbonding (NB) orbitals of diradical parent molecules, and these designed molecules are termed NB-TADF molecules. Based on this strategy, a series of NB-TADF molecules is finely designed and systematically studied by theoretical calculations. Taking advantage of the nonbonding properties, these NB-TADF molecules exhibit desirable narrowband emissions and high quantum yields. More importantly, the emission bands can be easily tuned from blue to near-infrared by changing the conjugate length of the parent group in the NB-TADF molecules. We hope that this new strategy can open a new door for the design of novel TADF materials.
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Affiliation(s)
- Shaoqin Zhang
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China
| | - Zhongjun Zhou
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China
| | - Zexing Qu
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China
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7
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Cheong K, Jo U, Hong WP, Lee JY. Fused Cycloalkyl Unit-Functionalized Tetradentate Pt(II) Complexes for Efficient and Narrow-Emitting Deep Blue Organic Light-Emitting Diodes. SMALL METHODS 2024; 8:e2300862. [PMID: 37926779 DOI: 10.1002/smtd.202300862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/18/2023] [Indexed: 11/07/2023]
Abstract
A blue tetradentate Pt(II) complex named Pt-tmCyCz is developed by introducing a cycloalkyl unit fused to carbazole to improve the rigidity and bulkiness of the complex. The introduction of the tetramethylcyclohexyl (tmCy) group results in a narrow full width at half maximum (FWHM), a high horizontal emitting dipole orientation, doping concentration resistant stable spectrum, and extremely small efficiency roll-off, and little concentration quenching effect. Phosphorescent organic light-emitting diodes (OLEDs) doped with Pt-tmCyCz achieve a high external quantum efficiency (EQE) of 21.5%, with a small EQE roll-off of 3.8% up to 1000 cd m-2 , a small FWHM of 24 nm, and a color coordinate of (0.132, 0.138). Moreover, Pt-tmCyCz is investigated as a sensitizer in phosphor-sensitized OLEDs using N7 ,N7 ,N13 ,N13 ,5,9,11,15-octaphenyl-5,9,11,15-tetrahydro-5,9,11,15-tetraaza-19b,20b-diboradinaphtho[3,2,1-de:1',2',3'-jk]pentacene-7,13-diamine (νDABNA) as a terminal emitter. The Pt-tmCyCz:νDABNA device achieves a high EQE of 33.9%, with a small EQE roll-off of only 8.0% up to 1 000 cd m-2 . The results demonstrate that fused tmCy group in carbazole can be an effective building block for the development of high-performance Pt(II) complexes, which can be utilized as efficient phosphors or sensitizers in OLEDs.
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Affiliation(s)
- Kiun Cheong
- School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 16419, Republic of Korea
| | - Unhyeok Jo
- School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 16419, Republic of Korea
| | - Wan Pyo Hong
- Department of Chemistry, Gachon University, 1342, Seongnam-daero,Sujeong-gu, Seongnam-si, Gyeonggi-do, 13120, Republic of Korea
| | - Jun Yeob Lee
- School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 16419, Republic of Korea
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi, 16419, Republic of Korea
- SKKU Institute of Energy Science and Technology, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi, 16419, Republic of Korea
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8
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Zender E, Karger S, Neubaur R, Virovets A, Lerner HW, Wagner M. Green-Emitting Extended B 3,N 2-Doped Polycyclic Aromatic Hydrocarbon with Multiple Resonance Structure. Org Lett 2024; 26:939-944. [PMID: 38266241 DOI: 10.1021/acs.orglett.3c04283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
An air-stable B3,N2-PAH (B3N2; nine annulated six-membered rings) was synthesized from 1-X-2,6-di(azasilaanthryl)benzenes (X = Cl, I) via lithiation/borylation, electrophilic aromatic borylation, and Si/B exchange. The heteroatom distribution in B3N2 meets the requirements for multiple resonance thermally activated delayed fluorescence (MR-TADF). Indeed, B3N2 emits green light (λem = 523 nm; ΦPL = 85%; CHCl3) with a small fwhm of 0.15 eV. Lifetimes for prompt (7.8 ns) and delayed (60 μs) fluorescence were measured in PMMA.
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Affiliation(s)
- Elena Zender
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, D-60438 Frankfurt (Main), Germany
| | - Sebastian Karger
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, D-60438 Frankfurt (Main), Germany
| | - Robert Neubaur
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, D-60438 Frankfurt (Main), Germany
| | - Alexander Virovets
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, D-60438 Frankfurt (Main), Germany
| | - Hans-Wolfram Lerner
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, D-60438 Frankfurt (Main), Germany
| | - Matthias Wagner
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Straße 7, D-60438 Frankfurt (Main), Germany
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9
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Blazevicius D, Siddiqui I, Gautam P, Krucaite G, Tavgeniene D, Nagar MR, Kumar K, Banik S, Jou JH, Grigalevicius S. Bicarbazole-Benzophenone-Based Twisted Donor-Acceptor-Donor Derivatives as Blue Emitters for Highly Efficient Fluorescent Organic Light-Emitting Diodes. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:146. [PMID: 38251111 PMCID: PMC10819850 DOI: 10.3390/nano14020146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 01/23/2024]
Abstract
This paper delves into the development of a group of twisted donor-acceptor-donor (D-A-D) derivatives incorporating bicarbazole as electron donor and benzophenone as electron acceptor for potential use as blue emitters in OLEDs. The derivatives were synthesized in a reaction of 4,4'-difluorobenzophenone with various 9-alkyl-9'H-3,3'-bicarbazoles. The materials, namely, DB14, DB23, and DB29, were designed with different alkyl side chains to enhance their solubility and film-forming properties of layers formed using the spin-coating from solution method. The new materials demonstrate high thermal stabilities with decomposition temperatures >383 °C, glass transition temperatures in the range of 95-145 °C, high blue photoluminescence quantum yields (>52%), and short decay times, which range in nanoseconds. Due to their characteristics, the derivatives were used as blue emitters in OLED devices. Some of the OLEDs incorporating the DB23 emitter demonstrated a high external quantum efficiency (EQEmax) of 5.3%, which is very similar to the theoretical limit of the first-generation devices.
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Affiliation(s)
- Dovydas Blazevicius
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu Plentas 19, LT50254 Kaunas, Lithuania
| | - Iram Siddiqui
- Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Guangfu Rd., East District, Hsinchu 30013, Taiwan
| | - Prakalp Gautam
- Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Guangfu Rd., East District, Hsinchu 30013, Taiwan
| | - Gintare Krucaite
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu Plentas 19, LT50254 Kaunas, Lithuania
| | - Daiva Tavgeniene
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu Plentas 19, LT50254 Kaunas, Lithuania
| | - Mangey Ram Nagar
- Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Guangfu Rd., East District, Hsinchu 30013, Taiwan
| | - Krishan Kumar
- School of Chemical Sciences, Indian Institute of Technology—Mandi, Kamand 175005, Himachal Pradesh, India
| | - Subrata Banik
- Department of Chemistry, School of Chemical and Biotechnology, SASTRA Deemed University, Thanjavur 613401, Tamil Nadu, India
| | - Jwo-Huei Jou
- Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Guangfu Rd., East District, Hsinchu 30013, Taiwan
| | - Saulius Grigalevicius
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu Plentas 19, LT50254 Kaunas, Lithuania
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10
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Wang J, Yang Y, Gu F, Zhai X, Yao C, Zhang J, Jiang C, Xi X. Molecular Engineering Modulating the Singlet-Triplet Energy Splitting of Indolocarbazole-Based TADF Emitters Exhibiting AIE Properties for Nondoped Blue OLEDs with EQE of Nearly 20. ACS APPLIED MATERIALS & INTERFACES 2023; 15:59643-59654. [PMID: 38090754 DOI: 10.1021/acsami.3c14230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
The development of efficient blue thermally activated delayed fluorescence (TADF) emitters with an aggregation-induced emission (AIE) nature, for the construction of organic light-emitting diodes (OLEDs), is still insufficient. This can be attributed to the challenges encountered in molecular design, including the inherent trade-off between radiative decay and reverse intersystem crossing (RISC), as well as small singlet-triplet energy splitting (ΔEST) and the requirement for high photoluminescence quantum yields (ΦPL). Herein, we present the design of three highly efficient blue TADF molecules with AIE characteristics by combining π-extended donors with different acceptors to modulate the differences in the electron-donating and electron-withdrawing abilities. This approach not only ensures high emission efficiency by suppressing close π-π stacking, weakening nonradiative relaxation, and enhancing radiative transition but also maintains the equilibrium ratio between the triplet and singlet excitons by facilitating the process of RISC. These emitters exhibit AIE and TADF properties, featuring quick radiative rates and low nonradiative rates. The ΦPL of these emitters reached an impressive 88%. Based on their excellent comprehensive performance, nondoped PICzPMO and PICzPMO OLEDs achieved excellent electroluminescence performance, exhibiting maximum external quantum efficiency (EQEmax) of up to 19.5%, while the doped device achieved a higher EQEmax of 20.8%. This work demonstrated that by fusing π-extended large rigid donors with different acceptors, it is possible to regulate the difference in electron-donating and electron-withdrawing abilities, resulting in a small ΔEST, high ΦPL, and fast RISC process, which is a highly feasible strategy for designing efficient TADF molecules.
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Affiliation(s)
- Jinshan Wang
- Jiangsu Provincial Key Laboratory of Eco-Environmental Materials, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China
| | - Yuguang Yang
- Jiangsu Provincial Key Laboratory of Eco-Environmental Materials, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China
| | - Fei Gu
- Jiangsu Provincial Key Laboratory of Eco-Environmental Materials, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China
| | - Xuesong Zhai
- Jiangsu Provincial Key Laboratory of Eco-Environmental Materials, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China
| | - Chuang Yao
- Chongqing Key Laboratory of Extraordinary Bond Engineering and Advance Materials Technology (EBEAM), Yangtze Normal University, Chongqing 408100, China
| | - Jianfeng Zhang
- School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Cuifeng Jiang
- Jiangsu Provincial Key Laboratory of Eco-Environmental Materials, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China
| | - Xinguo Xi
- Jiangsu Provincial Key Laboratory of Eco-Environmental Materials, School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China
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11
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Leitonas K, Vigante B, Volyniuk D, Bucinskas A, Dimitrijevs P, Lapcinska S, Arsenyan P, Grazulevicius JV. Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions. Beilstein J Org Chem 2023; 19:1867-1880. [PMID: 38116244 PMCID: PMC10729123 DOI: 10.3762/bjoc.19.139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 10/18/2023] [Indexed: 12/21/2023] Open
Abstract
The pyridine-3,5-dicarbonitrile moiety has gained significant attention in the field of materials chemistry, particularly in the development of heavy-metal-free pure organic light-emitting diodes (OLEDs). Extensive research on organic compounds exhibiting thermally activated delayed fluorescence (TADF) has led to numerous patents and research articles. This study focuses on the synthesis and investigation of the semiconducting properties of polyaromatic π-systems containing two and three fragments of pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile. The compounds are synthesized by Sonogashira coupling reactions and characterized by steady-state and time-resolved luminescence spectroscopy. The compounds show efficient intramolecular charge transfer (ICT) from the donor to the acceptor. The photoluminescence (PL) spectra of the solutions of the compounds showed non-structured emission peaks in the visible region, which are attributed to ICT emission. The PL intensities of the solutions of the compounds are enhanced after deoxygenation, which is indicative of TADF. The photoluminescence quantum yields and TADF properties of the compounds are sensitive to the medium. Cyclic voltammetry measurements indicate good hole-blocking and electron-injecting properties due to their high ionization potentials. Photoelectron spectroscopy and time-of-flight measurements reveal good electron-transporting properties for one of the compounds. In general, polyaromatic π-systems with pyridine-3,5-dicarbonitrile fragments demonstrate promising potential for use in organic electronic devices, such as OLEDs.
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Affiliation(s)
- Karolis Leitonas
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254, Kaunas, Lithuania
| | - Brigita Vigante
- Latvian Institute of Organic Synthesis, Aizkraukles 21, LV-1006, Riga, Latvia
| | - Dmytro Volyniuk
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254, Kaunas, Lithuania
| | - Audrius Bucinskas
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254, Kaunas, Lithuania
| | - Pavels Dimitrijevs
- Latvian Institute of Organic Synthesis, Aizkraukles 21, LV-1006, Riga, Latvia
| | - Sindija Lapcinska
- Latvian Institute of Organic Synthesis, Aizkraukles 21, LV-1006, Riga, Latvia
| | - Pavel Arsenyan
- Latvian Institute of Organic Synthesis, Aizkraukles 21, LV-1006, Riga, Latvia
| | - Juozas Vidas Grazulevicius
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254, Kaunas, Lithuania
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12
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Hodée M, Massue J, Achelle S, Fihey A, Tondelier D, Ulrich G, Guen FRL, Katan C. Styrylpyrimidine chromophores with bulky electron-donating substituents: experimental and theoretical investigation. Phys Chem Chem Phys 2023; 25:32699-32708. [PMID: 38014523 DOI: 10.1039/d3cp03705c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Styrylpyrimidines with bulky 9,9-dimethylacridan, phenoxazine and phenothiazine electron-donating fragments were designed. Thermally activated delayed fluorescence (TADF) properties were expected for these structures. These chromophores exhibit peculiar emission properties. For 9,9-dimethylacridan and phenoxazine derivatives, a single emission highly sensitive to the polarity is observed in solution whereas for phenothiazine derivative a dual emission is observed in solution and is attributed to the coexistence of quasi-axial (Qax) and quasi-equatorial (Qeq) conformers. This study intends to understand through theoretical and experimental works, why the studied chromophores do not exhibit TADF properties, contrary to what was expected. The absence of phosphorescence both at room temperature and 77 K tends to indicate the impossibility to harvest triplet states in these systems. Wave-function based calculations show that for both conformers of the three chromophores the S1-T1 splitting is significantly larger than 0.2 eV. The second triplet state T2 of Qeq conformers is found very close in energy to the singlet S1 state, but S1 and T2 states possess similar charge transfer characters. This prevents efficient spin-orbit coupling between the states, which is consistent with the absence of TADF.
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Affiliation(s)
- Maxime Hodée
- Univ Rennes, ENSCR, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France.
| | - Julien Massue
- Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé (ICPEES), UMR CNRS 7515, Equipe Chimie Organique pour la Biologie, les Matériaux et l'Optique (COMBO) 25 Rue Becquerel, 67087 Strasbourg, Cedex 02, France.
| | - Sylvain Achelle
- Univ Rennes, ENSCR, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France.
| | - Arnaud Fihey
- Univ Rennes, ENSCR, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France.
| | - Denis Tondelier
- Laboratoire de Physique des Interfaces et des Couches Minces (LPICM), CNRS, Ecole Polytechnique, IP Paris, Palaiseau Cedex, France
- Université Paris-Saclay, CEA, CNRS, NIMBE, LICSEN, Gif-sur-Yvette, France
| | - Gilles Ulrich
- Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé (ICPEES), UMR CNRS 7515, Equipe Chimie Organique pour la Biologie, les Matériaux et l'Optique (COMBO) 25 Rue Becquerel, 67087 Strasbourg, Cedex 02, France.
| | - Françoise Robin-le Guen
- Univ Rennes, ENSCR, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France.
| | - Claudine Katan
- Univ Rennes, ENSCR, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France.
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13
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Zhang T, Xiao Y, Wang H, Kong S, Huang R, Ka-Man Au V, Yu T, Huang W. Highly Twisted Thermally Activated Delayed Fluorescence (TADF) Molecules and Their Applications in Organic Light-Emitting Diodes (OLEDs). Angew Chem Int Ed Engl 2023; 62:e202301896. [PMID: 37288654 DOI: 10.1002/anie.202301896] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 06/07/2023] [Accepted: 06/07/2023] [Indexed: 06/09/2023]
Abstract
Thermally activated delayed fluorescence (TADF) materials have attracted great potential in the field of organic light-emitting diodes (OLEDs). Among thousands of TADF materials, highly twisted TADF emitters have become a hotspot in recent years. Compared with traditional TADF materials, highly twisted TADF emitters tend to show multi-channel charge-transfer characters and form rigid molecular structures. This is advantageous for TADF materials, as non-radiative decay processes can be suppressed to facilitate efficient exciton utilization. Accordingly, OLEDs with excellent device performances have also been reported. In this Review, we have summarized recent progress in highly twisted TADF materials and related devices, and give an overview of the molecular design strategies, photophysical studies, and the performances of OLED devices. In addition, the challenges and perspectives of highly twisted TADF molecules and the related OLEDs are also discussed.
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Affiliation(s)
- Tiantian Zhang
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Yuxin Xiao
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Hailan Wang
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Shuting Kong
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Rongjuan Huang
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Vonika Ka-Man Au
- Department of Science and Environmental Studies, The Education University of Hong Kong, 10 Lo Ping Road, Tai Po, New Territories, Hong Kong, China
| | - Tao Yu
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
- Key Laboratory of Flexible Electronics of Zhejiang Province, Ningbo Institute of Northwestern Polytechnical University, 218 Qingyi Road, 315103, Ningbo, China
| | - Wei Huang
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, 211816, Nanjing, China
- State Key Laboratory of Organic Electronics and Information Displays &, Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, 210023, Nanjing, China
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14
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Cao L, Liu X, Zhang X, Zhao J, Yu F, Wan Y. The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads. Beilstein J Org Chem 2023; 19:1028-1046. [PMID: 37497052 PMCID: PMC10366440 DOI: 10.3762/bjoc.19.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/07/2023] [Indexed: 07/28/2023] Open
Abstract
A series of 1,8-naphthalimide (NI)-phenothiazine (PTZ) electron donor-acceptor dyads were prepared to study the thermally activated delayed fluorescence (TADF) properties of the dyads, from a point of view of detection of the various transient species. The photophysical properties of the dyads were tuned by changing the electron-donating and the electron-withdrawing capability of the PTZ and NI moieties, respectively, by oxidation of the PTZ unit, or by using different aryl substituents attached to the NI unit. This tuning effect was manifested in the UV-vis absorption and fluorescence emission spectra, e.g., in the change of the charge transfer absorption bands. TADF was observed for the dyads containing the native PTZ unit, and the prompt and delayed fluorescence lifetimes changed with different aryl substituents on the imide part. In polar solvents, no TADF was observed. For the dyads with the PTZ unit oxidized, no TADF was observed as well. Femtosecond transient absorption spectra showed that the charge separation takes ca. 0.6 ps, and admixtures of locally excited (3LE) state and charge separated (1CS/3CS) states formed (in n-hexane). The subsequent charge recombination from the 1CS state takes ca. 7.92 ns. Upon oxidation of the PTZ unit, the beginning of charge separation is at 178 fs and formation of 3LE state takes 4.53 ns. Nanosecond transient absorption (ns-TA) spectra showed that both 3CS and 3LE states were observed for the dyads showing TADF, whereas only 3LE or 3CS states were observed for the systems lacking TADF. This is a rare but unambiguous experimental evidence that the spin-vibronic coupling of 3CS/3LE states is crucial for TADF. Without the mediating effect of the 3LE state, no TADF is resulted, even if the long-lived 3CS state is populated (lifetime τCS ≈ 140 ns). This experimental result confirms the 3CS → 1CS reverse intersystem crossing (rISC) is slow, without coupling with an approximate 3LE state. These studies are useful for an in-depth understanding of the photophysical mechanisms of the TADF emitters, as well as for molecular structure design of new electron donor-acceptor TADF emitters.
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Affiliation(s)
- Liyuan Cao
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, 2 Ling Gong Road, Dalian, 116024, P. R. China
| | - Xi Liu
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Xue Zhang
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, 2 Ling Gong Road, Dalian, 116024, P. R. China
| | - Jianzhang Zhao
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, 2 Ling Gong Road, Dalian, 116024, P. R. China
| | - Fabiao Yu
- Key Laboratory of Hainan Trauma and Disaster Rescue, The First Affiliated Hospital of Hainan Medical University, Hainan Medical University, Haikou 571199, P. R. China
| | - Yan Wan
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
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15
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Wu ZL, Lv X, Meng LY, Chen XL, Lu CZ. Tröger's Base-Derived Thermally Activated Delayed Fluorescence Dopant for Efficient Deep-Blue Organic Light-Emitting Diodes. Molecules 2023; 28:4832. [PMID: 37375387 DOI: 10.3390/molecules28124832] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 06/02/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
The development of efficient deep-blue emitters with thermally activated delayed fluorescence (TADF) properties is a highly significant but challenging task in the field of organic light-emitting diode (OLED) applications. Herein, we report the design and synthesis of two new 4,10-dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine (TB)-derived TADF emitters, TB-BP-DMAC and TB-DMAC, which feature distinct benzophenone (BP)-derived acceptors but share the same dimethylacridin (DMAC) donors. Our comparative study reveals that the amide acceptor in TB-DMAC exhibits a significantly weaker electron-withdrawing ability in comparison to that of the typical benzophenone acceptor employed in TB-BP-DMAC. This disparity not only causes a noticeable blue shift in the emission from green to deep blue but also enhances the emission efficiency and the reverse intersystem crossing (RISC) process. As a result, TB-DMAC emits efficient deep-blue delay fluorescence with a photoluminescence quantum yield (PLQY) of 50.4% and a short lifetime of 2.28 μs in doped film. The doped and non-doped OLEDs based on TB-DMAC display efficient deep-blue electroluminescence with spectral peaks at 449 and 453 nm and maximum external quantum efficiencies (EQEs) of 6.1% and 5.7%, respectively. These findings indicate that substituted amide acceptors are a viable option for the design of high-performance deep-blue TADF materials.
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Affiliation(s)
- Ze-Ling Wu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Lv
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, China
| | - Ling-Yi Meng
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, China
| | - Xu-Lin Chen
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, China
| | - Can-Zhong Lu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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16
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Urban M, Marek-Urban PH, Durka K, Luliński S, Pander P, Monkman AP. TADF Invariant of Host Polarity and Ultralong Fluorescence Lifetimes in a Donor-Acceptor Emitter Featuring a Hybrid Sulfone-Triarylboron Acceptor. Angew Chem Int Ed Engl 2023; 62:e202217530. [PMID: 36622736 DOI: 10.1002/anie.202217530] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/08/2023] [Accepted: 01/09/2023] [Indexed: 01/10/2023]
Abstract
10H-Dibenzo[b,e][1,4]thiaborinine 5,5-dioxide (SO2B)-a high triplet (T1 =3.05 eV) strongly electron-accepting boracycle was successfully utilised in thermally activated delayed fluorescence (TADF) emitters PXZ-Dipp-SO2B and CZ-Dipp-SO2B. We demonstrate the near-complete separation of highest occupied and lowest unoccupied molecular orbitals leading to a low oscillator strength of the S1 →S0 CT transition, resulting in very long ca. 83 ns and 400 ns prompt fluorescence lifetimes for CZ-Dipp-SO2B and PXZ-Dipp-SO2B, respectively, but retaining near unity photoluminescence quantum yield. OLEDs using CZ-Dipp-SO2B as the luminescent dopant display high external quantum efficiency (EQE) of 23.3 % and maximum luminance of 18600 cd m-2 with low efficiency roll off at high brightness. For CZ-Dipp-SO2B, reverse intersystem crossing (rISC) is mediated through the vibronic coupling of two charge transfer (CT) states, without involving the triplet local excited state (3 LE), resulting in remarkable rISC rate invariance to environmental polarity and polarisability whilst giving high organic light-emitting diode (OLED) efficiency. This new form of rISC allows stable OLED performance to be achieved in different host environments.
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Affiliation(s)
- Mateusz Urban
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland.,Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK
| | - Paulina H Marek-Urban
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Krzysztof Durka
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Sergiusz Luliński
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Piotr Pander
- Faculty of Chemistry, Silesian University of Technology, Strzody 9, 44-100, Gliwice, Poland.,Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK
| | - Andrew P Monkman
- Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK
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17
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Weber F, Mori H. On donor-acceptor-bridging intramolecular hydrogen bonds in NIR-TADF molecules. RSC Adv 2023; 13:3942-3946. [PMID: 36756563 PMCID: PMC9891092 DOI: 10.1039/d2ra07450h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 01/20/2023] [Indexed: 01/28/2023] Open
Abstract
Following a report that highlights the importance of intramolecular hydrogen bonds for improved NIR-TADF efficiency in CAT-1 [Leng et al., J. Phys Chem. A, 2021, 125, 2905], an intramolecularly doubly hydrogen-bonded base design is investigated and compared to singly and non-bonded derivatives. It is found that the potential to form more intramolecular hydrogen bonds correlates with decreasing internal reorganization energies in most of the designed structures. In addition, our proposed base design facilitates the desired interlocking of charge transfer donor-, linker- and acceptor-planes through steric gauche-interactions to both linker-plane sides, allowing to trap also smaller heterocyclic linkers.
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Affiliation(s)
- Fabian Weber
- Chuo University, Department of Applied Chemistry Kasuga 1-13-27 112-8551 Tokyo-to Bunkyo-ku Japan
| | - Hirotoshi Mori
- Chuo University, Department of Applied Chemistry Kasuga 1-13-27 112-8551 Tokyo-to Bunkyo-ku Japan
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18
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Haselbach W, Kaminski JM, Kloeters LN, Müller TJJ, Weingart O, Marian CM, Gilch P, Nogueira de Faria BE. A Thermally Activated Delayed Fluorescence Emitter Investigated by Time-Resolved Near-Infrared Spectroscopy. Chemistry 2023; 29:e202202809. [PMID: 36214291 PMCID: PMC10098753 DOI: 10.1002/chem.202202809] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Indexed: 11/18/2022]
Abstract
Emitters for organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) require small singlet (S1 )-triplet (T1 ) energy gaps as well as fast intersystem crossing (ISC) transitions. These transitions can be mediated by vibronic mixing with higher excited states Sn and Tn (n=2, 3, 4, …). For a prototypical TADF emitter consisting of a triarylamine and a dicyanobenzene moiety (TAA-DCN) it is shown that these higher states can be located energetically by time-resolved near-infrared (NIR) spectroscopy.
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Affiliation(s)
- Wiebke Haselbach
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Jeremy M Kaminski
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Laura N Kloeters
- Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Thomas J J Müller
- Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Oliver Weingart
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Christel M Marian
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Peter Gilch
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Barbara E Nogueira de Faria
- Institut für Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
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19
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Gao Y, Wu S, Shan G, Cheng G. Recent Progress in Blue Thermally Activated Delayed Fluorescence Emitters and Their Applications in OLEDs: Beyond Pure Organic Molecules with Twist D-π-A Structures. MICROMACHINES 2022; 13:2150. [PMID: 36557449 PMCID: PMC9784815 DOI: 10.3390/mi13122150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 11/26/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Thermally activated delayed fluorescence (TADF) materials, which can harvest all excitons and emit light without the use of noble metals, are an appealing class of functional materials emerging as next-generation organic electroluminescent materials. Triplet excitons can be upconverted to the singlet state with the aid of ambient thermal energy under the reverse inter-system crossing owing to the small singlet-triplet splitting energy (ΔEST). This results from a specific molecular design consisting of minimal overlap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, due to the spatial separation of the electron-donating and electron-releasing part. When a well-designed device structure is applied, high-performance blue-emitting TADF organic light-emitting diodes can be realized with an appropriate molecular design. Unlike the previous literature that has reviewed general blue-emitting TADF materials, in this paper, we focus on materials other than pure organic molecules with twist D-π-A structures, including multi-resonance TADF, through-space charge transfer TADF, and metal-TADF materials. Cutting-edge molecules with extremely small and even negative ΔEST values are also introduced as candidates for next-generation TADF materials. In addition, OLED structures used to exploit the merits of the abovementioned TADF emitters are also described in this review.
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Affiliation(s)
- Yiting Gao
- State Key Laboratory of Synthetic Chemistry, Department of Chemistry, The University of Hong Kong, Hong Kong, China
- Institute of Functional Material Chemistry and National & Local United Engineering Lab for Power Battery, Faculty of Chemistry, Northeast Normal University, Changchun 130024, China
| | - Siping Wu
- State Key Laboratory of Synthetic Chemistry, Department of Chemistry, The University of Hong Kong, Hong Kong, China
| | - Guogang Shan
- Institute of Functional Material Chemistry and National & Local United Engineering Lab for Power Battery, Faculty of Chemistry, Northeast Normal University, Changchun 130024, China
| | - Gang Cheng
- State Key Laboratory of Synthetic Chemistry, Department of Chemistry, The University of Hong Kong, Hong Kong, China
- HKU Shenzhen Institute of Research and Innovation, Shenzhen 518053, China
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20
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Ferraro V, Castro J, Agostinis L, Bortoluzzi M. Dual-emitting Mn(II) and Zn(II) halide complexes with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide as ligand. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.121285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Effect of host polarity on efficiency of thermally activated delayed fluorescent and hyperfluorescent organic light emitting devices. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.09.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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22
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Ulukan P, Bas EE, Ozek RB, Dal Kaynak C, Monari A, Aviyente V, Catak S. Computational descriptor analysis on excited state behaviours of a series of TADF and non-TADF compounds. Phys Chem Chem Phys 2022; 24:16167-16182. [PMID: 35748918 DOI: 10.1039/d2cp01323a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The thermally activated delayed fluorescence (TADF) behaviours of seventeen organic TADF emitters and two non-TADF chromophores bearing various donor and acceptor moieties were investigated, focusing on their torsion angles, singlet-triplet gap (ΔEST), spin orbit couplings (SOC) and topological ΦS index. Electronic structure calculations were performed in the framework of the Tamm-Dancoff approximation (TDA) allowing the possible reverse intersystem crossing (RISC) pathways to be characterized. The electronic density reorganization of the excited states was checked also with respect to the different exchange-correlation functional and absorption spectra were obtained by considering vibrational and dynamical effects through Wigner sampling of the ground state equilibrium regions. Examining all the parameters obtained in our computational study, we rationalized the influence of electron-donating and electron-accepting groups and the effects of geometrical factors, especially torsion angles, on a wide class of diverse compounds ultimately providing an easy and computationally effective protocol to assess TADF efficiencies.
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Affiliation(s)
- Pelin Ulukan
- Department of Chemistry, Bogazici University, Bebek, 34342, Istanbul, Turkey.
| | - Ekin Esme Bas
- Department of Chemistry, Bogazici University, Bebek, 34342, Istanbul, Turkey.
| | - Rengin Busra Ozek
- Department of Chemistry, Bogazici University, Bebek, 34342, Istanbul, Turkey.
| | - Cansul Dal Kaynak
- Department of Chemistry, Bogazici University, Bebek, 34342, Istanbul, Turkey.
| | - Antonio Monari
- Université de Lorraine and CNRS, LPCT UMR 7019, F-54000 Nancy, France.,Université de Paris and CNRS, Itodys, F-75006 Paris, France
| | - Viktorya Aviyente
- Department of Chemistry, Bogazici University, Bebek, 34342, Istanbul, Turkey.
| | - Saron Catak
- Department of Chemistry, Bogazici University, Bebek, 34342, Istanbul, Turkey.
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23
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Wiefermann J, Schmeinck P, Ganter C, Müller TJJ. Highly Deep‐Blue Luminescent Twisted Diphenylamino Terphenyl Emitters by Bromine‐Lithium Exchange Borylation‐Suzuki Sequence. Chemistry 2022; 28:e202200576. [PMID: 35298846 PMCID: PMC9322521 DOI: 10.1002/chem.202200576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Indexed: 11/11/2022]
Abstract
Four novel intensively blue luminescent chromophores were readily synthesized by bromine‐lithium exchange borylation‐Suzuki (BLEBS) sequence in moderate to good yields. Their electronic properties were studied by absorption and emission spectroscopy and quantum chemical calculations revealing deep‐blue emission in solution as well as in the solid state and upon embedding into a PMMA (polymethylmethacrylate) matrix with small FWHM (full width at half maximum) values and CIE y values smaller than 0.1. Moreover, high photoluminescence quantum yields (PLQY), partially close to unity, are found.
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Affiliation(s)
- Julia Wiefermann
- Institut für Organische Chemie und Makromolekulare Chemie Heinrich-Heine-Universität Düsseldorf Universitätsstraße 1 D-40225 Düsseldorf Germany
| | - Philipp Schmeinck
- Institut für Anorganische Chemie und Strukturchemie I Heinrich-Heine-Universität Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Christian Ganter
- Institut für Anorganische Chemie und Strukturchemie I Heinrich-Heine-Universität Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Thomas J. J. Müller
- Institut für Organische Chemie und Makromolekulare Chemie Heinrich-Heine-Universität Düsseldorf Universitätsstraße 1 D-40225 Düsseldorf Germany
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24
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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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25
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Yu J, Qiu S, Zhang K, Zhou T, Ban X, Duan Y, Jia D, Zhu Q, Zhang T. A novel thermally-activated delayed fluorescent probe based on hydroxyl as identify group for detection of iron ions. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2021.132074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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26
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Wei Z, Zuo T, Jiang S, Qi F, Yang M, Meng L, Lu CZ. Theoretically elucidating high photoluminescence performance of dimethylacridan-based blue-color thermally activated delayed fluorescent materials. NEW J CHEM 2022. [DOI: 10.1039/d1nj05251a] [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
Based on first-principles methods, we comprehensively quantify the luminous quantum efficiencies and related photophysical process rates of dimethylacridan-based blue-color TADF emitters.
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Affiliation(s)
- Zhuangzhuang Wei
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Tao Zuo
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Shanshan Jiang
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Fangfang Qi
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Mingxue Yang
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Lingyi Meng
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Can-Zhong Lu
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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27
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Okuda Y, Fujimoto M, Akashi H, Orita A. Dephosphinylative [4 + 2] Benzannulation of Phosphinyl Ynamines: Application to the Modular Synthesis of Polycyclic Aromatic Amines. J Org Chem 2021; 86:17651-17666. [PMID: 34860520 DOI: 10.1021/acs.joc.1c01897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of 9-amino-10-halophenanthrenes were synthesized through a one-pot process, including dephosphinylative Sonogashira-Hagihara coupling of 2-bromobiphenyls with air-stable phosphinyl ynamines, followed by halonium-promoted [4 + 2] benzannulation of the resulting 2-(aminoethynyl)biphenyls. Nonsubstituted and methyl-substituted 2-bromobiphenyls rapidly underwent the Sonogashira-Hagihara aminoethynylation and the halogenative Friedel-Crafts benzannulation to provide the corresponding amino(halo)phenanthrenes in high yields, while electron-sufficient and -deficient substrates did slowly undergo the former and the latter to result in low yields, respectively. This protocol worked well for the syntheses of highly π-extended aminophenanthrenes and aminobenzonaphthothiophenes with different optical properties. Further application of this approach between 2,2″- and 2',5'-dibromo-p-terphenyls with phosphinyl ynamines led to the regioselective formation of 6,13-diamino-5,12-dihalo- and 5,12-diamino-6,13-dihalo-dibenz[a,h]anthracenes via dual aminoethynylation and [4 + 2] benzannulation. The obtained analogues showed different ultraviolet-visible absorption and photoluminescence spectra with different emission quantum yields in CH2Cl2 solution and the powder state.
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Affiliation(s)
- Yasuhiro Okuda
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
| | - Mayo Fujimoto
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
| | - Haruo Akashi
- Institute of Frontier Science and Technology, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
| | - Akihiro Orita
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
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28
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De Silva TPD, Youm SG, Fronczek FR, Sahasrabudhe G, Nesterov EE, Warner IM. Pyrene-Benzimidazole Derivatives as Novel Blue Emitters for OLEDs. Molecules 2021; 26:molecules26216523. [PMID: 34770936 PMCID: PMC8588490 DOI: 10.3390/molecules26216523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/22/2021] [Accepted: 10/24/2021] [Indexed: 11/16/2022] Open
Abstract
Three novel small organic heterocyclic compounds: 2-(1,2-diphenyl)-1H-benzimidazole-7-tert-butylpyrene (compound A), 1,3-di(1,2-diphenyl)-1H-benzimidazole-7-tert-butylpyrene (compound B), and 1,3,6,8-tetra(1,2-diphenyl)-1H-benzimidazolepyrene (compound C) were synthesized and characterized for possible applications as blue OLED emitters. The specific molecular design targeted decreasing intermolecular aggregation and disrupting crystallinity in the solid-state, in order to reduce dye aggregation, and thus obtain efficient pure blue photo- and electroluminescence. Accordingly, the new compounds displayed reasonably high spectral purity in both solution- and solid-states with average CIE coordinates of (0.160 ± 0.005, 0.029 ± 0.009) in solution and (0.152 ± 0.007, 0.126 ± 0.005) in solid-state. These compounds showed a systematic decrease in degree of crystallinity and intermolecular aggregation due to increasing steric hindrance, as revealed using powder X-ray diffraction analysis and spectroscopic studies. An organic light-emitting diode (OLED) prototype fabricated using compound B as the non-doped emissive layer displayed an external quantum efficiency (EQE) of 0.35 (±0.04)% and luminance 100 (±6) cd m−2 at 5.5 V with an essentially pure blue electroluminescence corresponding to CIE coordinates of (0.1482, 0.1300). The highest EQE observed from this OLED prototype was 4.3 (±0.3)% at 3.5 V, and the highest luminance of 290 (±10) cd m−2 at 7.5 V. These values were found comparable to characteristics of the best pure blue OLED devices based on simple fluorescent small-molecule organic chromophores.
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Affiliation(s)
| | - Sang Gil Youm
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, USA; (S.G.Y.); (E.E.N.)
| | - Frank R. Fronczek
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA; (T.P.D.D.S.); (F.R.F.); (G.S.)
| | - Girija Sahasrabudhe
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA; (T.P.D.D.S.); (F.R.F.); (G.S.)
| | - Evgueni E. Nesterov
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, USA; (S.G.Y.); (E.E.N.)
| | - Isiah M. Warner
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA; (T.P.D.D.S.); (F.R.F.); (G.S.)
- Correspondence: ; Tel.: +1-225-578-2829; Fax: +1-225-578-3971
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29
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30
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Xu H, Lin J, Jiang X, Jin Y, Lin Z, Zhang X, Li X, Yang H, Wu Z. Study on the difference in exciton generation processes for a single host and exciplex-type co-host. OPTICS LETTERS 2021; 46:4840-4843. [PMID: 34598213 DOI: 10.1364/ol.439516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/01/2021] [Indexed: 06/13/2023]
Abstract
We distinctly reveal the difference in the exciton generation processes in phosphorescent organic light-emitting devices with an exciplex-type co-host and a single host. Excitons in the co-host consisting of 4,4,4-tris(N-carbazolyl)-triphenylamine and 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene are created via efficient energy transfer from the exciplex to the phosphorescent dopant. In contrast, excitons in the single host of 4,4,4-tris(N-carbazolyl)-triphenylamine are formed by the combination of holes and electrons trapped by the phosphorescent dopants. The optimized device utilizing the co-host system exhibits highly superior performance relative to the single-host device. The maximum external quantum efficiency and maximum luminance are 14.88% and 90,700cd/m2 for the co-host device, being 1.6 times and 3.6 times the maximum external efficiency and maximum luminance for the single-host device, respectively. Significantly, the critical current density, evaluating the device efficiency roll-off characteristic, is as high as 327.8mA/cm2, which is highly superior to 120.8mA/cm2 for the single-host device, indicating the notable alleviation in efficiency roll-off for the co-host device. The significant improvement in device performance is attributed to eliminating the exciton quenching resulting from the captured holes and the efficient energy transfer from the exciplex-type co-host to the phosphorescent emitter incurred by the reverse intersystem crossing process.
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31
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Ma M, Li J, Liu D, Mei Y, Dong R. Rational Utilization of Intramolecular Hydrogen Bonds to Achieve Blue TADF with EQEs of Nearly 30% and Single Emissive Layer All-TADF WOLED. ACS APPLIED MATERIALS & INTERFACES 2021; 13:44615-44627. [PMID: 34517701 DOI: 10.1021/acsami.1c11812] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A series of highly efficient blue thermally activated delayed fluorescence (TADF) compounds, SON-Cz, SON-tBuCz, and SON-PhCz, were developed. Pyridinyl was introduced as the bridging unit between carbazole donors and sulfone acceptor. Intramolecular hydrogen bonds between the pyridine N atom and carbazole H atoms were detected in single crystals, which suppressed the twisting of carbazole rings and dramatically increased the molecular rigidity. At the same time, tert-butyl or phenyl were incorporated at the 3,6-sites of carbazole ring to tune electron donating ability or enlarge HOMO delocalization. All these hydrogen bonds featured TADF compounds exhibited much improved photoluminescence quantum yields (PLQYs) and excellent efficiencies in their doped blue organic light-emitting diodes. In particular, SON-tBuCz and SON-PhCz exhibited the maximum external quantum efficiencies (EQEs) of 29.59% and 28.22% with CIE coordinates of (0.17, 0.22) and (0.21, 0.36), respectively. The excellent performance benefits from the carbazole structure modification and the intramolecular hydrogen bonds, which bring more rigid structures and eliminate nonradiative transitions. Furthermore, a single emissive layer all-TADF white OLED was fabricated using SON-tBuCz as the blue emitter and 4CzTPN-Ph as the orange emitter to give an EQE of 23.51% with a high CRI of 71, which is among the top efficiencies ever reported for all-TADF WOLEDs so far.
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Affiliation(s)
- Mengyao Ma
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Jiuyan Li
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Di Liu
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, China
| | - Yongqiang Mei
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Ruizhi Dong
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
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32
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Tsuchiya Y, Diesing S, Bencheikh F, Wada Y, Dos Santos PL, Kaji H, Zysman-Colman E, Samuel IDW, Adachi C. Exact Solution of Kinetic Analysis for Thermally Activated Delayed Fluorescence Materials. J Phys Chem A 2021; 125:8074-8089. [PMID: 34473511 DOI: 10.1021/acs.jpca.1c04056] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photophysical analysis of thermally activated delayed fluorescence (TADF) materials has become instrumental for providing insights into their stability and performance, which is not only relevant for organic light-emitting diodes but also for other applications such as sensing, imaging, and photocatalysis. Thus, a deeper understanding of the photophysics underpinning the TADF mechanism is required to push materials design further. Previously reported analyses in the literature of the kinetics of the various processes occurring in a TADF material rely on several a priori assumptions to estimate the rate constants for forward and reverse intersystem crossing. In this report, we demonstrate a method to determine these rate constants using a three-state model together with a steady-state approximation and, importantly, no additional assumptions. Further, we derive the exact rate equations, greatly facilitating a comparison of the TADF properties of structurally diverse emitters and providing a comprehensive understanding of the photophysics of these systems.
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Affiliation(s)
- Youichi Tsuchiya
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Stefan Diesing
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, Fife, St Andrews KY16 9ST, U.K.,Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, Fife, St Andrews KY16 9ST, U.K
| | - Fatima Bencheikh
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yoshimasa Wada
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Paloma L Dos Santos
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, Fife, St Andrews KY16 9ST, U.K
| | - Hironori Kaji
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, Fife, St Andrews KY16 9ST, U.K
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, Fife, St Andrews KY16 9ST, U.K
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan.,International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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Sobolewski AL, Domcke W. Are Heptazine-Based Organic Light-Emitting Diode Chromophores Thermally Activated Delayed Fluorescence or Inverted Singlet-Triplet Systems? J Phys Chem Lett 2021; 12:6852-6860. [PMID: 34279950 DOI: 10.1021/acs.jpclett.1c01926] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two chromophores derived from heptazine, HAP-3MF and HAP-3TPA, were synthesized and tested as emitters in light-emitting diodes (OLEDs) by Adachi and co-workers. Both emitters were shown to exhibit quantum efficiencies which exceed the theoretical maximum of conventional fluorescent OLEDs. The enhanced emission efficiency was explained by the mechanism of thermally activated delayed fluorescence (TADF). In the present work, the electronic excitation energies and essential features of the topography of the excited-state potential-energy surfaces of HAP-3MF and HAP-3TPA have been investigated with a wave function-based ab initio method (ADC(2)). It is found that HAP-3MF is an inverted singlet-triplet (IST) system; that is, the energies of the S1 and T1 states are robustly inverted in violation of Hund's multiplicity rule. Notably, HAP-3MF presumably is the first IST emitter which was implemented in an OLED device. In HAP-3TPA, on the other hand, the vertical excitation energies of the S1 and T1 states are essentially degenerate. The excited states exhibit vibrational stabilization energies of similar magnitude along different relaxation coordinates, resulting in adiabatic excitation energies which also are nearly degenerate. HAP-3TPA is found to be a chromophore at the borderline of TADF and IST systems. The spectroscopic data reported by Adachi and co-workers for HAP-3MF and HAP-3TPA are analyzed in light of these computational results.
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Affiliation(s)
| | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, Garching, Germany
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34
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Efficient Deep-Blue Electroluminescence Employing Heptazine-Based Thermally Activated Delayed Fluorescence. PHOTONICS 2021. [DOI: 10.3390/photonics8080293] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We report an efficient deep-blue organic light-emitting diode (OLED) based on a heptazine-based thermally activated delayed fluorescent (TADF) emitter, 2,5,8-tris(diphenylamine)-tri-s-triazine (HAP-3DPA). The deep-blue-emitting compound, HAP-3DPA, was designed and synthesized by combining the relatively rigid electron-accepting heptazine core with three electron-donating diphenylamine units. Due to the rigid molecular structure and intramolecular charge transfer characteristics, HAP-3DPA in solid state presented a high photoluminescence quantum yield of 67.0% and obvious TADF nature with a short delayed fluorescent lifetime of 1.1 μs. Most importantly, an OLED incorporating HAP-3DPA exhibited deep-blue emission with Commission Internationale de l’Eclairage (CIE) coordinates of (0.16, 0.13), a peak luminance of 10,523 cd/m−2, and a rather high external quantum efficiency of 12.5% without any light out-coupling enhancement. This finding not only reports an efficient deep-blue TADF molecule, but also presents a feasible pathway to construct high-performance deep-blue emitters and devices based on the heptazine skeleton.
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Vieira AA, Farias G, Costa WC, Eccher J, Bechtold IH, Durola F, Bock H. Nematic Triphenyltriazine Triesters and the Induction of the Columnar Mesophase by Fluorine Substitution. Chemistry 2021; 27:9003-9010. [PMID: 33871125 DOI: 10.1002/chem.202005456] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Indexed: 11/06/2022]
Abstract
Whereas their para homologs are not mesogenic, the disk-shaped triphenyltriazine meta-trialkylesters obtained via trimerization of 3-cyanobenzoic alkylester, which are configurationally more flexible, exhibit a monotropic nematic mesophase. Introduction of fluorine atoms into the alkyl chains or into the phenyl moieties leads to the appearance of an enantiotropic columnar mesophase. If fluorine is introduced both in the chains and in the phenyl moieties, only a monotropic mesophase remains. Fluorination of either the alkyl chains or the aromatic core, but not both, appears thus as a simple means of inducing or stabilizing columnar self-assembly in disk-shaped systems. As the homeotropically alignable columnar mesophase can thus be made to persist at room temperature, as energies higher than 3 eV of the first excited triplet state are computed in agreement with the value reported for the parent arene, and as they are not fluorescent themselves, these compounds are of promise as aligning host matrices for blue-emitting TADF devices with improved light outcoupling. Dilution of a columnar with a nonmesogenic homolog induces the nematic state, indicating that the nanoscopic make-up of both mesophases is closely related.
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Affiliation(s)
- André A Vieira
- Instituto de Química, Universidade Federal da Bahia, 40170-115, Salvador, BA, Brazil
| | - Giliandro Farias
- Departamento de Química, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Wallison C Costa
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Juliana Eccher
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Ivan H Bechtold
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Fabien Durola
- Centre de Recherche Paul Pascal, CNRS & Université de Bordeaux 115 av. Schweitzer, 33600, Pessac, France
| | - Harald Bock
- Centre de Recherche Paul Pascal, CNRS & Université de Bordeaux 115 av. Schweitzer, 33600, Pessac, France
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Pios S, Huang X, Sobolewski AL, Domcke W. Triangular boron carbon nitrides: an unexplored family of chromophores with unique properties for photocatalysis and optoelectronics. Phys Chem Chem Phys 2021; 23:12968-12975. [PMID: 34059871 DOI: 10.1039/d1cp02026a] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
It has recently been shown that cycl[3.3.3]azine and heptazine (1,3,4,6,7,9,9b-heptaazaphenalene) as well as related azaphenalenes exhibit inverted singlet and triplet states, that is, the energy of the lowest singlet excited state (S1) is below the energy of the lowest triplet excited state (T1). This feature is unique among all known aromatic chromophores and is of outstanding relevance for applications in photocatalysis and organic optoelectronics. Heptazine is the building block of the polymeric material graphitic carbon nitride which is an extensively explored photocatalyst in hydrogen evolution photocatalysis. Derivatives of heptazine have also been identified as efficient emitters in organic light emitting diodes (OLEDs). In both areas, the inverted singlet-triplet gap of heptazine is a highly beneficial feature. In photocatalysis, the absence of a long-lived triplet state eliminates the activation of atmospheric oxygen, which is favourable for long-term operational stability. In optoelectronics, singlet-triplet inversion implies the possibility of 100% fluorescence efficiency of electron-hole recombination. However, the absorption and luminescence wavelengths of heptazine and the S1-S0 transition dipole moment are difficult to tune for optimal functionality. In this work, we employed high-level ab initio electronic structure theory to devise and characterize a large family of novel heteroaromatic chromophores, the triangular boron carbon nitrides. These novel heterocycles inherit essential spectroscopic features from heptazine, in particular the inverted singlet-triplet gap, while their absorption and luminescence spectra and transition dipole moments are widely tuneable. For applications in photocatalysis, the wavelength of the absorption maximum can be tuned to improve the overlap with the solar spectrum at the surface of earth. For applications in OLEDs, the colour of emission can be adjusted and the fluorescence yield can be enhanced.
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Affiliation(s)
- Sebastian Pios
- Department of Chemistry, Technical University of Munich, 85747 Garching, Germany.
| | - Xiang Huang
- Department of Chemistry, Technical University of Munich, 85747 Garching, Germany.
| | | | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, 85747 Garching, Germany.
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Maeda B, Mori G, Sakakibara Y, Yagi A, Murakami K, Itami K. Photo‐Induced Arylation of Carbazoles With Aryldiazonium Salts. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Bumpei Maeda
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Graduate School of Science Nagoya University, Chikusa Nagoya 464-8602 Japan
| | - Genki Mori
- Central Pharmaceutical Research Institute Japan Tobacco Inc. 1-1 Murasaki-cho, Takatsuki Osaka 569-1125 Japan
| | - Yota Sakakibara
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Graduate School of Science Nagoya University, Chikusa Nagoya 464-8602 Japan
| | - Akiko Yagi
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Graduate School of Science Nagoya University, Chikusa Nagoya 464-8602 Japan
| | - Kei Murakami
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Graduate School of Science Nagoya University, Chikusa Nagoya 464-8602 Japan
- Department of Chemistry School of Science and Technology Kwansei Gakuin University 2-1 Gakuen, Sanda Hyogo 669-1337 Japan
- JST-PRESTO 7 Gobancho, Chiyoda Tokyo 102-0076 Japan
| | - Kenichiro Itami
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Graduate School of Science Nagoya University, Chikusa Nagoya 464-8602 Japan
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Effect of TADF Assistance on Performance Enhancement in Solution Processed Green Phosphorescent OLEDs. Polymers (Basel) 2021; 13:polym13071148. [PMID: 33918499 PMCID: PMC8038252 DOI: 10.3390/polym13071148] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/26/2021] [Accepted: 03/30/2021] [Indexed: 01/12/2023] Open
Abstract
Many methods have been proposed to increase the efficiency of organic electroluminescent materials applied as an emissive layer in organic light emitting diodes (OLEDs). Herein, we demonstrate enhancement of electroluminescence efficiency and operational stability solution processed OLEDs by employing thermally activated delayed fluorescence (TADF) molecules as assistant dopants in host-guest systems. The TADF assistant dopant (SpiroAC–TRZ) is used to facilitate efficient energy transfer from host material poly(N–vinylcarbazole) (PVK) to a phosphorescent Ir(III) emitter. We present the analysis of energy transfer and charge trapping—two main processes playing a crucial role in light generation in host–guest structure OLEDs. The investigation of photo-, electro- and thermoluminescence for the double-dopant layer revealed that assistant dopant does not only harvest and transfer the electrically generated excitons to phosphorescent emitter molecules but also creates exciplexes. The triplet states of formed PVK:SpiroAC–TRZ exciplexes are involved in the transport process of charge carriers and promote long–range exciton energy transfer to the emitter, improving the efficiency of electroluminescence in a single emissive layer OLED, resulting in devices with luminance exceeding 18 000 cd/m2 with a luminous efficiency of 23 cd/A and external quantum efficiency (EQE) of 7.4%.
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39
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Patil VV, Lim J, Lee JY. Strategic Synchronization of 7,7-Dimethyl-5,7-dihydroindeno[2,1- b]carbazole for Narrow-Band, Pure Violet Organic Light-Emitting Diodes with an Efficiency of > 5% and a CIE y Coordinate of < 0.03. ACS APPLIED MATERIALS & INTERFACES 2021; 13:14440-14446. [PMID: 33749250 DOI: 10.1021/acsami.1c02635] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A novel violet emitter, 1,3-bis[10,10-dimethyl-10H-indeno[2,1-b]]indolo[3,2,1-jk]indolo[1',2',3':1,7]indolo[3,2-b]carbazole (m-FLDID), was designed and synthesized by meta-oriented bis-fusion of two 7,7-dimethyl-5,7-dihydroindeno[2,1-b]carbazole (DMID) subunits for use in a pure violet organic light-emitting diode (OLED). Incorporation of the DMID subunits effectively reduced the nonradiative recombination rate, improving the photoluminescence quantum yield of the m-FLDID emitter. The meta-oriented bis-fusion of the two DMID subunits not only triggered an alternative distribution of the frontier orbitals but also effectively locked the π-conjugation chain, which ultimately resulted in a narrow-band, pure violet emission of the m-FLDID emitter. Doped m-FLDID devices possessed an external quantum efficiency (EQE) of > 5%, pure violet emission with a maximum at 407 nm, a narrow full width at half-maximum of 17 nm, and a Commission Internationale de l'éclairage y coordinate of less than 0.03. This is the first work reporting an EQE of > 5% and an extremely narrow emission spectrum for a pure violet emitter.
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Affiliation(s)
- Vilas Venunath Patil
- School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 440-746, Korea
| | - Junseop Lim
- School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 440-746, Korea
| | - Jun Yeob Lee
- School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 440-746, Korea
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40
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Hu Y, Li L, Wang X, Ma D, Huang F. Three-dimensional organic cage with aggregation-induced delayed fluorescence. CHINESE CHEM LETT 2021. [DOI: 10.1016/j.cclet.2020.08.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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41
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Wang L, Ou Q, Peng Q, Shuai Z. Theoretical Characterizations of TADF Materials: Roles of ΔG and the Singlet–Triplet Excited States Interconversion. J Phys Chem A 2021; 125:1468-1475. [DOI: 10.1021/acs.jpca.0c09767] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Lu Wang
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People’s Republic of China
| | - Qi Ou
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People’s Republic of China
| | - Qian Peng
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Zhigang Shuai
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People’s Republic of China
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42
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Alkoxy encapsulation of carbazole-based thermally activated delayed fluorescent dendrimers for highly efficient solution-processed organic light-emitting diodes. CHINESE CHEM LETT 2021. [DOI: 10.1016/j.cclet.2020.06.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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43
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Busch JM, Koshelev DS, Vashchenko AA, Fuhr O, Nieger M, Utochnikova VV, Bräse S. Various Structural Design Modifications: para-Substituted Diphenylphosphinopyridine Bridged Cu(I) Complexes in Organic Light-Emitting Diodes. Inorg Chem 2021; 60:2315-2332. [PMID: 33464050 DOI: 10.1021/acs.inorgchem.0c03187] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The well-known system of dinuclear Cu(I) complexes bridged by 2-(diphenylphosphino)pyridine (PyrPhos) derivatives Cu2X2L3 and Cu2X2LP2 (L = bridging ligand, P = ancillary ligand) goes along with endless variation options for tunability. In this work, the influence of substituents and modifications on the phosphine moiety of the NP-bridging ligand was investigated. In previous studies, the location of the lowest unoccupied molecular orbital (LUMO) of the copper complexes of the PyrPhos family was found to be located on the NP-bridging ligand and enabled color tuning in the whole visible spectrum. A multitude of dinuclear Cu(I) complexes based on the triple methylated 2-(bis(4-methylphenyl)phosphino)-4-methylpyridine (Cu-1b-H, Cu-1b-MeO, and Cu-1b-F) up to complexes bearing 2-(bis(4-fluorophenyl)phosphino)pyridine (Cu-6a-H) with electron-withdrawing fluorine atoms over many other variations on the NP-bridging ligands were synthesized. Almost all copper complexes were confirmed via single crystal X-ray diffraction analysis. Besides theoretical TDDFT-studies of the electronic properties and photophysical measurements, the majority of the phosphino-modified Cu(I) complexes was tested in solution-processed organic light-emitting diodes (OLEDs) with different heterostructure variations. The best results of the OLED devices were obtained with copper emitter Cu-1b-H in a stack architecture of ITO/PEDOT-PSS (50 nm)/poly-TPD (15 nm)/20 wt % Cu(I) emitter:CBP:TcTA(7:3) (45 nm)/TPBi (30 nm)/LiF(1 nm)/Al (>100 nm) with a high brightness of 5900 Cd/m2 and a good current efficiency of 3.79 Cd/A.
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Affiliation(s)
- Jasmin M Busch
- Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Karlsruhe, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Daniil S Koshelev
- Faculty of Materials Science, M.V. Lomonosov Moscow State University, 1/73 Leninskye Gory, Moscow, 119991, Russia
| | | | - Olaf Fuhr
- Institute of Nanotechnology (INT) and Karlsruhe Nano-Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Martin Nieger
- Department of Chemistry, University of Helsinki, P.O. Box 55, A.I. Virtasen aukio 1, 00014, Helsinki, Finland
| | | | - Stefan Bräse
- Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Karlsruhe, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.,Institute of Biological and Chemical Systems - Functional Molecular Systems, IBCS-FMS, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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44
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Khammultri P, Kitisriworaphan W, Chasing P, Namuangruk S, Sudyoadsuk T, Promarak V. Efficient white light-emitting polymers from dual thermally activated delayed fluorescence chromophores for non-doped solution processed white electroluminescent devices. Polym Chem 2021. [DOI: 10.1039/d0py01541e] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Conjugated TADF copolymers comprised of two TADF molecules linked with carbazole exhibited stable pure white emission from non-doped OLEDs with CIE coordinates (0.32, 0.35), a maximum luminance efficiency of 9.13 cd A−1, and a maximum EQE of 4.17%.
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Affiliation(s)
- Praetip Khammultri
- Department of Materials Science and Engineering
- School of Molecular Science & Engineering
- Vidyasirimedhi Institute of Science and Technology
- Wangchan
- Thailand
| | - Wipaporn Kitisriworaphan
- School of Chemistry
- Institute of Science
- Suranaree University of Technology
- Nakhon Ratchasima 30000
- Thailand
| | - Pongsakorn Chasing
- Department of Materials Science and Engineering
- School of Molecular Science & Engineering
- Vidyasirimedhi Institute of Science and Technology
- Wangchan
- Thailand
| | - Supawadee Namuangruk
- National Nanotechnology Center (NANOTEC)
- National Science and Technology Development Agency
- Pathum Thani
- Thailand
| | - Taweesak Sudyoadsuk
- Department of Materials Science and Engineering
- School of Molecular Science & Engineering
- Vidyasirimedhi Institute of Science and Technology
- Wangchan
- Thailand
| | - Vinich Promarak
- Department of Materials Science and Engineering
- School of Molecular Science & Engineering
- Vidyasirimedhi Institute of Science and Technology
- Wangchan
- Thailand
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45
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Nyga A, Izumi S, Higginbotham HF, Stachelek P, Pluczyk S, Silva P, Minakata S, Takeda Y, Data P. Electrochemical and Spectroelectrochemical Comparative Study of Macrocyclic Thermally Activated Delayed Fluorescent Compounds: Molecular Charge Stability vs OLED EQE Roll‐Off. ASIAN J ORG CHEM 2020. [DOI: 10.1002/ajoc.202000475] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Aleksandra Nyga
- Faculty of Chemistry Silesian University of Technology M. Strzody 9 44–100 Gliwice Poland
| | - Saika Izumi
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamadaoka 2–1, Suita Osaka 5650871 Japan
| | | | - Patrycja Stachelek
- Physics Department Durham University South Road Durham DH1 3LE United Kingdom
| | - Sandra Pluczyk
- Faculty of Chemistry Silesian University of Technology M. Strzody 9 44–100 Gliwice Poland
| | - Piotr Silva
- Department of Energy Conversion and Storage Technical University of Denmark Anker Engelunds Vej 301 2800 Kgs. Lyngby Denmark
| | - Satoshi Minakata
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamadaoka 2–1, Suita Osaka 5650871 Japan
| | - Youhei Takeda
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamadaoka 2–1, Suita Osaka 5650871 Japan
| | - Przemyslaw Data
- Faculty of Chemistry Silesian University of Technology M. Strzody 9 44–100 Gliwice Poland
- Centre of Polymer and Carbon Materials Polish Academy of Science M. Curie-Sklodowskiej 34 41–819 Zabrze Poland
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46
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Li F, Li M, Fan J, Song Y, Wang CK, Lin L. Theoretical Study on Thermally Activated Delayed Fluorescence Emitters in White Organic Light-Emitting Diodes: Emission Mechanism and Molecular Design. J Phys Chem A 2020; 124:7526-7537. [DOI: 10.1021/acs.jpca.0c06695] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Feiyan 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
| | - Muzhen 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
| | - 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
| | - 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
| | - 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
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47
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Fluorinated Tolane Dyads with Alkylene Linkage: Synthesis and Evaluation of Photophysical Characteristics. CRYSTALS 2020. [DOI: 10.3390/cryst10080711] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Light-emitting materials have received considerable attention because of their broad applications as substrates in bio-imaging and sensing components, light-emitting displays, and lighting devices. Herein, we developed fluorinated tolane and bistolane derivatives containing fluorinated aromatic rings and demonstrated their intense photoluminescence (PL) characteristics in crystalline powder states. We focused on molecules showing varied PL behavior with a change in the molecular aggregated structures. We synthesized novel fluorinated tolane dyads consisting of fluorinated tolane-based π-conjugated scaffolds and flexible alkylene linkages to control both the electron-density distribution and molecular aggregated states. Fluorinated tolane dyads connected with an alkylene linkage showed blue PL in a dilute solution, but the PL efficiency achieved was low. In contrast, the crystalline powder of tolane dyad substrates exhibited dual emission—relatively intense blue to deep blue PL—originating from monomer and aggregate emission. The PL behavior changed significantly with the alkylene linkage and the application of a mechanical stimulus to the crystalline powder sample. The fluorinated tolane dyads developed in this study could serve as stimulus-responsive photoluminescent materials suitable for optical applications.
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48
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Non-symmetric 9,10-Di(2-naphthyl)anthracene derivatives as hosts and emitters for solution-processed blue fluorescent organic light emitting diodes. J IND ENG CHEM 2020. [DOI: 10.1016/j.jiec.2020.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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49
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Qian S, Pu X, Chang G, Huang Y, Yang Y. Rh(III)-Catalyzed Oxidative C–H Activation/Domino Annulation of Anilines with 1,3-Diynes: A Rapid Access to Blue-Emitting Tricyclic N,O-Heteroaromatics. Org Lett 2020; 22:5309-5313. [DOI: 10.1021/acs.orglett.0c01465] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Shengyou Qian
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Xingwen Pu
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Guanjun Chang
- State Key Laboratory of Environment-friendly Energy Materials, School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China
| | - Ying Huang
- State Key Laboratory of Environment-friendly Energy Materials, School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China
| | - Yudong Yang
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
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Crucho CIC, Avó J, Diniz AM, Pinto SN, Barbosa J, Smith PO, Berberan-Santos MN, Pålsson LO, Dias FB. TADF Dye-Loaded Nanoparticles for Fluorescence Live-Cell Imaging. Front Chem 2020; 8:404. [PMID: 32457878 PMCID: PMC7227253 DOI: 10.3389/fchem.2020.00404] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 04/17/2020] [Indexed: 02/03/2023] Open
Abstract
Thermally activated delayed fluorescence (TADF) molecules offer nowadays a powerful tool in the development of novel organic light emitting diodes due to their capability of harvesting energy from non-emissive triplet states without using heavy-metal complexes. TADF emitters have very small energy difference between the singlet and triplet excited states, which makes thermally activated reverse intersystem crossing from the triplet states back to the singlet manifold viable. This mechanism generates a long-lived delayed fluorescence component which can be explored in the sensing of oxygen concentration, local temperature, or used in time-gated optical cell-imaging, to suppress interference from autofluorescence and scattering. Despite this strong potential, until recently the application of TADF outside lighting devices has been hindered due to the low biocompatibility, low aqueous solubility and poor performance in polar media shown by the vast majority of TADF emitters. To achieve TADF luminescence in biological media, careful selection or design of emitters is required. Unfortunately, most TADF molecules are not emissive in polar media, thus complexation with biomolecules or the formation of emissive aggregate states is required, in order to retain the delayed fluorescence that is characteristic of these compounds. Herein, we demonstrate a facile method with great generalization potential that maintains the photophysical properties of solvated dyes by combining luminescent molecules with polymeric nanoparticles. Using an established swelling procedure, two known TADF emitters are loaded onto polystyrene nanoparticles to prepare TADF emitting nanomaterials able to be used in live-cell imaging. The obtained particles were characterized by optical spectroscopy and exhibited the desired TADF emission in aqueous media, due to the polymeric matrix shielding the dye from solvent polarity effects. The prepared nanoparticles were incubated with live human cancer cells and showed very low cytotoxicity and good cellular uptake, thus making fluorescence microscopy imaging possible at low dye concentrations.
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Affiliation(s)
- Carina I C Crucho
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - João Avó
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Ana M Diniz
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Sandra N Pinto
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - José Barbosa
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Poppy O Smith
- Department of Chemistry, Durham University, Durham, United Kingdom
| | - Mário Nuno Berberan-Santos
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | | | - Fernando B Dias
- Department of Physics, Durham University, Durham, United Kingdom
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