1
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Lv L, Zhang Y, Ning Z. Deciphering the doublet luminescence mechanism in neutral organic radicals: spin-exchange coupling, reversed-quartet mechanism, excited-state dynamics. RSC Adv 2024; 14:23987-23999. [PMID: 39086516 PMCID: PMC11289762 DOI: 10.1039/d4ra03566f] [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: 05/15/2024] [Accepted: 07/17/2024] [Indexed: 08/02/2024] Open
Abstract
Neutral organic radical molecules have recently attracted considerable attention as promising luminescent and quantum-information materials. However, the presence of a radical often shortens their excited-state lifetime and results in fluorescence quenching due to enhanced intersystem crossing (EISC). Recently, an experimental report introduced an efficient luminescent radical molecule, tris(2,4,6-trichlorophenyl)methyl-carbazole-anthracene (TTM-1Cz-An). In this study, we systematically performed quantum theoretical calculations combined with the path integral approach to quantitatively calculate the excited-state dynamics processes and spectral characteristics. Our theoretical findings suggest that the sing-doublet D1 state, originating from the anthracene excited singlet state, is quickly converted to the doublet (trip-doublet) state via EISC, facilitated by a significant nonequivalence exchange interaction, with ΔJ ST = 0.174 cm-1. The formation of the quartet state (Q1, trip-quartet) was predominantly dependent on the exchange coupling 3/2J TR = 0.086 cm-1 between the triplet spin electrons of anthracene and the TTM-1Cz radical. Direct spin-orbit coupling ISC to the Q1 state was minimal due to the nearly identical spatial wavefunctions of the and Q1 levels. The effective occurrence of reverse intersystem crossing (RISC) from the Q1 to D1 state is a critical step in controlling the luminescence of TTM-1Cz-An. The calculated RISC rate k RISC, including the Herzberg-Teller effect, was 3.64 × 105 s-1 at 298 K, significantly exceeding the phosphorescence and nonradiative rates of the Q1 state, thus enabling the D1 repopulation. Subsequently, a strong electronic coupling of 37.4 meV was observed between the D1 and D2 states, along with a dense manifold of doublet states near the D1 state energy, resulting in a larger reverse internal conversion rate k RIC of 9.26 × 1010 s-1. Distributed to the D2 state, the obtained emission rate of k f = 2.98-3.18 × 107 s-1 was in quite good agreement with the experimental value of 1.28 × 107 s-1, and its temperature effect was not remarkable. Our study not only provides strong support for the experimental findings but also offers valuable insights for the molecular design of high-efficiency radical emitters.
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Affiliation(s)
- LingLing Lv
- School of Chemical Engineering and Technology, Tianshui Normal University Tianshui Gansu 741001 China /
- Key Laboratory of Advanced Optoelectronic Functional Materials of Gansu Province, Tianshui Normal University Tianshui Gansu 741001 China
| | - YanYing Zhang
- School of Chemical Engineering and Technology, Tianshui Normal University Tianshui Gansu 741001 China /
| | - ZiYe Ning
- School of Chemical Engineering and Technology, Tianshui Normal University Tianshui Gansu 741001 China /
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2
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Fang C, Xu C, Zhang W, Zhou M, Tan D, Qian L, Hu D, Jin S, Zhu M. Dual-quartet phosphorescent emission in the open-shell M 1Ag 13 (M = Pt, Pd) nanoclusters. Nat Commun 2024; 15:5962. [PMID: 39013901 PMCID: PMC11252300 DOI: 10.1038/s41467-024-50289-x] [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: 02/06/2024] [Accepted: 07/01/2024] [Indexed: 07/18/2024] Open
Abstract
Dual emission (DE) in nanoclusters (NCs) is considerably significant in the research and application of ratiometric sensing, bioimaging, and novel optoelectronic devices. Exploring the DE mechanism in open-shell NCs with doublet or quartet emissions remains challenging because synthesizing open-shell NCs is difficult due to their inherent instability. Here, we synthesize two dual-emissive M1Ag13(PFBT)6(TPP)7 (M = Pt, Pd; PFBT = pentafluorobenzenethiol; TPP = triphenylphosphine) NCs with a 7-electron open-shell configuration to reveal the DE mechanism. Both NCs comprise a crown-like M1Ag11 kernel with Pt or Pd in the center surrounded by five PPh3 ligands and two Ag(SR)3(PPh3) motifs. The combined experimental and theoretical studies revealed the origin of DE in Pt1Ag13 and Pd1Ag13. Specifically, the high-energy visible emission and the low-energy near-infrared emission arise from two distinct quartet excited states: the core-shell charge transfer and core-based states, respectively. Moreover, PFBT ligands are found to play an important role in the existence of DE, as its low-lying π* levels result in energetically accessible core-shell transitions. This novel report on the dual-quartet phosphorescent emission in NCs with an open-shell electronic configuration advances insights into the origin of dual-emissive NCs and promotes their potential application in magnetoluminescence and novel optoelectronic devices.
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Affiliation(s)
- Cao Fang
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui University, Hefei, Anhui, 230601, China
- Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Anhui University, Hefei, Anhui, 230601, China
| | - Chang Xu
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui University, Hefei, Anhui, 230601, China
| | - Wei Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Meng Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Dong Tan
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui University, Hefei, Anhui, 230601, China
- Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Anhui University, Hefei, Anhui, 230601, China
| | - Lixia Qian
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui University, Hefei, Anhui, 230601, China
| | - Daqiao Hu
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui University, Hefei, Anhui, 230601, China.
- Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Anhui University, Hefei, Anhui, 230601, China.
| | - Shan Jin
- Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Anhui University, Hefei, Anhui, 230601, China.
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui, 230601, China.
| | - Manzhou Zhu
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui University, Hefei, Anhui, 230601, China.
- Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Anhui University, Hefei, Anhui, 230601, China.
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3
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Mizuno A, Matsuoka R, Kimura S, Ochiai K, Kusamoto T. Spin-Correlated Luminescence of a Carbazole-Containing Diradical Emitter: Single-Molecule Magnetoluminescence and Thermally Activated Emission. J Am Chem Soc 2024; 146:18470-18483. [PMID: 38921686 DOI: 10.1021/jacs.4c03972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
Luminescent radicals have been intensively studied as a new class of materials exhibiting novel photofunctions unique to open-shell systems. When luminescent radicals are assembled, intriguing spin-correlated luminescence phenomena emerge, including excimer-like emission and magnetic-field effects on luminescence (i.e., magnetoluminescence, MagLum). However, the underlying mechanisms of these phenomena arising from spin multiplicity and spin-dependent excited-state dynamics are poorly understood due to the limited number of luminescent polyradical systems available for study. In particular, the correlation between stronger intramolecular exchange interactions (|2J/kB| > ∼10 K, where J and kB are the intramolecular exchange coupling constant and the Boltzmann constant, respectively) and luminescence properties has not been fully explained. In this study, a novel carbazole-containing diradical emitter (1) and the corresponding monoradical (2) were prepared for the in-depth study of spin-correlated luminescence properties, with luminescence measurements under magnetic fields of up to 18 T. Diradical 1 has a negative 2J/kB value of several tens of kelvin and exhibits a single-molecule MagLum and thermally activated luminescence, whereas 2 does not. Detailed quantitative analyses revealed that both the spin-correlated luminescence properties of 1 are strongly dominated by ground-state spin statistics based on the Boltzmann distribution (i.e., 2J/kB values). Furthermore, diradical 1 exhibits external heavy-atom effects in heavy-atom-containing solvents such as iodobenzene, whereas monoradical 2 does not. This is the first experimental verification of external heavy-atom effects in polyradical emitters. This work demonstrates that polyradical emitters can be designed based on spin degrees of freedom in both ground and excited states.
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Affiliation(s)
- Asato Mizuno
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Division of Chemistry, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Ryota Matsuoka
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Division of Chemistry, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193, Japan
| | - Shojiro Kimura
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Keisuke Ochiai
- SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193, Japan
| | - Tetsuro Kusamoto
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- Division of Chemistry, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193, Japan
- JST-PRESTO, 4-1-8, Honcho, Kawaguchi, Saitama 332-0012, Japan
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4
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Gou Q, Guan J, Zhang L, Ai X. Phenyl Derivatives Modulate the Luminescent Properties and Stability of CzBTM-Type Radicals. Molecules 2024; 29:2900. [PMID: 38930965 PMCID: PMC11206717 DOI: 10.3390/molecules29122900] [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: 05/21/2024] [Revised: 06/15/2024] [Accepted: 06/16/2024] [Indexed: 06/28/2024] Open
Abstract
The distinctive electron structures of luminescent radicals offer considerable potential for a diverse array of applications. Up to now, the luminescent properties of radicals have been modulated through the introduction of electron-donating substituents, predominantly derivatives of carbazole and polyaromatic amines with more and more complicated structures and redshifted luminescent spectra. Herein, four kinds of (N-carbazolyl)bis(2,4,6-tirchlorophenyl)-methyl (CzBTM) radicals, Ph2CzBTM, Mes2CzBTM, Ph2PyIDBTM, and Mes2PyIDBTM, were synthesized and characterized by introducing simple phenyl and 2,4,6-trimethylphenyl groups to CzBTM and PyIDBTM. These radicals exhibit rare blueshifted emission spectra compared to their parent radicals. Furthermore, modifications to CzBTM significantly enhanced the photoluminescence quantum yields (PLQYs), with a highest PLQY of 21% for Mes2CzBTM among CzBTM-type radicals. Additionally, the molecular structures, photophysical properties of molecular orbitals, and stability of the four radicals were systematically investigated. This study provides a novel strategy for tuning the luminescent color of radicals to shorter wavelengths and improving thermostability.
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Affiliation(s)
- Quanquan Gou
- School of Materials Science and Engineering, Hainan University, No 58, Renmin Avenue, Haikou 570228, China
| | - Jiahao Guan
- School of Materials Science and Engineering, Hainan University, No 58, Renmin Avenue, Haikou 570228, China
| | - Lintao Zhang
- School of Materials Science and Engineering, Hainan University, No 58, Renmin Avenue, Haikou 570228, China
- Collaborative Innovation Center of Marine Science and Technology, Hainan University, No 58, Renmin Avenue, Haikou 570228, China
| | - Xin Ai
- School of Materials Science and Engineering, Hainan University, No 58, Renmin Avenue, Haikou 570228, China
- Collaborative Innovation Center of Marine Science and Technology, Hainan University, No 58, Renmin Avenue, Haikou 570228, China
- Collaborative Innovation Center of Information Technology, Hainan University, No 58, Renmin Avenue, Haikou 570228, China
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5
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Ghosh P, Alvertis AM, Chowdhury R, Murto P, Gillett AJ, Dong S, Sneyd AJ, Cho HH, Evans EW, Monserrat B, Li F, Schnedermann C, Bronstein H, Friend RH, Rao A. Decoupling excitons from high-frequency vibrations in organic molecules. Nature 2024; 629:355-362. [PMID: 38720042 PMCID: PMC11078737 DOI: 10.1038/s41586-024-07246-x] [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: 09/20/2022] [Accepted: 02/27/2024] [Indexed: 05/12/2024]
Abstract
The coupling of excitons in π-conjugated molecules to high-frequency vibrational modes, particularly carbon-carbon stretch modes (1,000-1,600 cm-1) has been thought to be unavoidable1,2. These high-frequency modes accelerate non-radiative losses and limit the performance of light-emitting diodes, fluorescent biomarkers and photovoltaic devices. Here, by combining broadband impulsive vibrational spectroscopy, first-principles modelling and synthetic chemistry, we explore exciton-vibration coupling in a range of π-conjugated molecules. We uncover two design rules that decouple excitons from high-frequency vibrations. First, when the exciton wavefunction has a substantial charge-transfer character with spatially disjoint electron and hole densities, we find that high-frequency modes can be localized to either the donor or acceptor moiety, so that they do not significantly perturb the exciton energy or its spatial distribution. Second, it is possible to select materials such that the participating molecular orbitals have a symmetry-imposed non-bonding character and are, thus, decoupled from the high-frequency vibrational modes that modulate the π-bond order. We exemplify both these design rules by creating a series of spin radical systems that have very efficient near-infrared emission (680-800 nm) from charge-transfer excitons. We show that these systems have substantial coupling to vibrational modes only below 250 cm-1, frequencies that are too low to allow fast non-radiative decay. This enables non-radiative decay rates to be suppressed by nearly two orders of magnitude in comparison to π-conjugated molecules with similar bandgaps. Our results show that losses due to coupling to high-frequency modes need not be a fundamental property of these systems.
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Affiliation(s)
- Pratyush Ghosh
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Antonios M Alvertis
- KBR, Inc., NASA Ames Research Center, Moffett Field, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Petri Murto
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | | | - Shengzhi Dong
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, China
| | | | - Hwan-Hee Cho
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Emrys W Evans
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
- Department of Chemistry, Swansea University, Swansea, UK
| | - Bartomeu Monserrat
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK
| | - Feng Li
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, China
| | | | - Hugo Bronstein
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | | | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, Cambridge, UK.
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6
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Lv K, Zhang M, Xia X, Liu W, Wan K, Zhang M, Li F. Cyano modified triphenylmethyl radical skeletons: higher stability and efficiency. Chem Commun (Camb) 2024; 60:4846-4849. [PMID: 38619487 DOI: 10.1039/d4cc00903g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
We introduced cyano groups to replace chlorine atoms in the tris(2,4,6-trichlorophenyl)methyl (TTM) radical skeleton, resulting in two cyano-modified TTM skeletons. The incorporation of cyano groups effectively suppresses nonradiative transition processes and lowers the frontier molecular orbital energy levels compared to those of the TTM radical. Consequently, enhanced photoluminescence quantum efficiency (PLQE) and a shift towards longer-wavelength emission in solution were achieved. Furthermore, the cyano-modified TTM skeletons exhibited improved stabilities. The development of these two skeletons adds diversity to stable organic luminescent radical skeletons.
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Affiliation(s)
- Kuo Lv
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
| | - Minzhe Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
| | - Xin Xia
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
| | - Wenjing Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
| | - Keke Wan
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
| | - Ming Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
| | - Feng Li
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
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Nakamura K, Matsuda K, Xiaotian R, Furukori M, Miyata S, Hosokai T, Anraku K, Nakao K, Albrecht K. Effects of halogen atom substitution on luminescent radicals: a case study on tris(2,4,6-trichlorophenyl)methyl radical-carbazole dyads. Faraday Discuss 2024; 250:192-201. [PMID: 37966049 DOI: 10.1039/d3fd00130j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
A series of halogen-substitute carbazole TTM radicals was synthesized. The effect of halogen substituents on radical luminescence was systematically evaluated. It was found that the well-known heavy atom effect does not work in the emission of radicals and that halogen substitution of the donor carbazole can change the HOMO and alter the absorption and emission wavelengths. In addition, the photostability was found to be improved with respect to TTM but not significantly different from that of closed-shell fluorescent molecules.
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Affiliation(s)
- Kazuhiro Nakamura
- Department of Applied Science for Electronics and Materials, Interdisciplinery Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580, Japan
| | - Kenshiro Matsuda
- Department of Applied Science for Electronics and Materials, Interdisciplinery Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580, Japan
| | - Rui Xiaotian
- Department of Applied Science for Electronics and Materials, Interdisciplinery Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580, Japan
| | - Minori Furukori
- Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Satoshi Miyata
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Takuya Hosokai
- Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Kosuke Anraku
- Department of Applied Science for Electronics and Materials, Interdisciplinery Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580, Japan
| | - Kohei Nakao
- Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-Koen Kasuga-Shi, Fukuoka 816-8580, Japan.
| | - Ken Albrecht
- Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-Koen Kasuga-Shi, Fukuoka 816-8580, Japan.
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8
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Ju CW, Shen Y, French EJ, Yi J, Bi H, Tian A, Lin Z. Accurate Electronic and Optical Properties of Organic Doublet Radicals Using Machine Learned Range-Separated Functionals. J Phys Chem A 2024. [PMID: 38382058 DOI: 10.1021/acs.jpca.3c07437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Luminescent organic semiconducting doublet-spin radicals are unique and emergent optical materials because their fluorescent quantum yields (Φfl) are not compromised by the spin-flipping intersystem crossing (ISC) into a dark high-spin state. The multiconfigurational nature of these radicals challenges their electronic structure calculations in the framework of single-reference density functional theory (DFT) and introduces room for method improvement. In the present study, we extended our earlier development of ML-ωPBE [J. Phys. Chem. Lett., 2021, 12, 9516-9524], a range-separated hybrid (RSH) exchange-correlation (XC) functional constructed using the stacked ensemble machine learning (SEML) algorithm, from closed-shell organic semiconducting molecules to doublet-spin organic semiconducting radicals. We assessed its performance for a new test set of 64 doublet-spin radicals from five categories while placing all previously compiled 3926 closed-shell molecules in the new training set. Interestingly, ML-ωPBE agrees with the nonempirical OT-ωPBE functional regarding the prediction of the molecule-dependent range-separation parameter (ω), with a small mean absolute error (MAE) of 0.0197 a0-1, but saves the computational cost by 2.46 orders of magnitude. This result demonstrates an outstanding domain adaptation capacity of ML-ωPBE for diverse organic semiconducting species. To further assess the predictive power of ML-ωPBE in experimental observables, we also applied it to evaluate absorption and fluorescence energies (Eabs and Efl) using linear-response time-dependent DFT (TDDFT), and we compared its behavior with nine popular XC functionals. For most radicals, ML-ωPBE reproduces experimental measurements of Eabs and Efl with small MAEs of 0.299 and 0.254 eV, only marginally different from those of OT-ωPBE. Our work illustrates a successful extension of the SEML framework from closed-shell molecules to doublet-spin radicals and will open the venue for calculating optical properties for organic semiconductors using single-reference TDDFT.
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Affiliation(s)
- Cheng-Wei Ju
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Yili Shen
- Manning College of Information and Computer Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Ethan J French
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - Jun Yi
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, United States
| | - Hongshan Bi
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Aaron Tian
- Manning College of Information and Computer Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Zhou Lin
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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9
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Lüer L, Wang R, Liu C, Dube H, Heumüller T, Hauch J, Brabec CJ. Maximizing Performance and Stability of Organic Solar Cells at Low Driving Force for Charge Separation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2305948. [PMID: 38039433 PMCID: PMC10853714 DOI: 10.1002/advs.202305948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/19/2023] [Indexed: 12/03/2023]
Abstract
Thanks to the development of novel electron acceptor materials, the power conversion efficiencies (PCE) of organic photovoltaic (OPV) devices are now approaching 20%. Further improvement of PCE is complicated by the need for a driving force to split strongly bound excitons into free charges, causing voltage losses. This review discusses recent approaches to finding efficient OPV systems with minimal driving force, combining near unity quantum efficiency (maximum short circuit currents) with optimal energy efficiency (maximum open circuit voltages). The authors discuss apparently contradicting results on the amount of exciton binding in recent literature, and approaches to harmonize the findings. A comprehensive view is then presented on motifs providing a driving force for charge separation, namely hybridization at the donor:acceptor interface and polarization effects in the bulk, of which quadrupole moments (electrostatics) play a leading role. Apart from controlling the energies of the involved states, these motifs also control the dynamics of recombination processes, which are essential to avoid voltage and fill factor losses. Importantly, all motifs are shown to depend on both molecular structure and process conditions. The resulting high dimensional search space advocates for high throughput (HT) workflows. The final part of the review presents recent HT studies finding consolidated structure-property relationships in OPV films and devices from various deposition methods, from research to industrial upscaling.
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Affiliation(s)
- Larry Lüer
- Institute of Materials for Electronics and Energy Technology (i‐MEET)Friedrich‐Alexander‐Universität Erlangen‐NürnbergMartensstrasse 791058ErlangenGermany
| | - Rong Wang
- Institute of Materials for Electronics and Energy Technology (i‐MEET)Friedrich‐Alexander‐Universität Erlangen‐NürnbergMartensstrasse 791058ErlangenGermany
- Erlangen Graduate School in Advanced Optical Technologies (SAOT)Paul‐Gordan‐Straße 691052ErlangenGermany
| | - Chao Liu
- Institute of Materials for Electronics and Energy Technology (i‐MEET)Friedrich‐Alexander‐Universität Erlangen‐NürnbergMartensstrasse 791058ErlangenGermany
| | - Henry Dube
- Department Chemistry and PharmacyFriedrich‐Alexander‐Universität Erlangen‐NürnbergNikolaus‐Fiebiger‐Straße 1091058ErlangenGermany
| | - Thomas Heumüller
- Institute of Materials for Electronics and Energy Technology (i‐MEET)Friedrich‐Alexander‐Universität Erlangen‐NürnbergMartensstrasse 791058ErlangenGermany
| | - Jens Hauch
- Helmholtz‐Institute Erlangen‐Nürnberg (HI‐ERN)Immerwahrstraße 291058ErlangenGermany
| | - Christoph J. Brabec
- Institute of Materials for Electronics and Energy Technology (i‐MEET)Friedrich‐Alexander‐Universität Erlangen‐NürnbergMartensstrasse 791058ErlangenGermany
- Helmholtz‐Institute Erlangen‐Nürnberg (HI‐ERN)Immerwahrstraße 291058ErlangenGermany
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10
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Yuan JW, Peng QC, Fu JC, Yang Q, Gao ZY, Wang ZY, Li K, Zang SQ, Tang BZ. Highly Efficient Stable Luminescent Radical-Based X-ray Scintillator. J Am Chem Soc 2023. [PMID: 38016919 DOI: 10.1021/jacs.3c11027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
Stable luminescent radicals are open-shell emitters with unique doublet emission characteristics. This feature makes stable luminescent radicals exhibit widespread application prospects in constructing optical, electrical, and magnetic materials. In this work, a stable luminescent radical-based X-ray scintillator of AuPP-1.0 was prepared, which exhibited a high X-ray excited luminescence (XEL) efficiency as well as excellent stability. A mechanism study showed that the heavy atom of Au in AuPP-1.0 endowed it with effective absorption of X-rays, and the doublet emission characteristics of AuPP-1.0 significantly increased its exciton utilization rate in the radioluminescence process. Moreover, AuPP-1.0 has good processability to fabricate a flexible screen for high-quality X-ray imaging, whose resolution can reach 20 LP mm-1. This work demonstrates that the doublet emission is beneficial for improving the exciton utilization rate of radioluminescence, providing a brand-new strategy for the construction of high-performance X-ray scintillators.
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Affiliation(s)
- Jia-Wang Yuan
- Tianjian Laboratory of Advanced Biomedical Sciences, Institute of Advanced Biomedical Sciences, Henan Key Laboratory of Crystalline Molecular Functional Materials, Henan International Joint Laboratory of Tumor Theranostical Cluster Materials, Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
| | - Qiu-Chen Peng
- Tianjian Laboratory of Advanced Biomedical Sciences, Institute of Advanced Biomedical Sciences, Henan Key Laboratory of Crystalline Molecular Functional Materials, Henan International Joint Laboratory of Tumor Theranostical Cluster Materials, Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
| | - Jia-Cong Fu
- Tianjian Laboratory of Advanced Biomedical Sciences, Institute of Advanced Biomedical Sciences, Henan Key Laboratory of Crystalline Molecular Functional Materials, Henan International Joint Laboratory of Tumor Theranostical Cluster Materials, Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
| | - Qi Yang
- Tianjian Laboratory of Advanced Biomedical Sciences, Institute of Advanced Biomedical Sciences, Henan Key Laboratory of Crystalline Molecular Functional Materials, Henan International Joint Laboratory of Tumor Theranostical Cluster Materials, Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
| | - Zi-Ying Gao
- Tianjian Laboratory of Advanced Biomedical Sciences, Institute of Advanced Biomedical Sciences, Henan Key Laboratory of Crystalline Molecular Functional Materials, Henan International Joint Laboratory of Tumor Theranostical Cluster Materials, Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
| | - Zhao-Yang Wang
- Tianjian Laboratory of Advanced Biomedical Sciences, Institute of Advanced Biomedical Sciences, Henan Key Laboratory of Crystalline Molecular Functional Materials, Henan International Joint Laboratory of Tumor Theranostical Cluster Materials, Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
| | | | - Shuang-Quan Zang
- Tianjian Laboratory of Advanced Biomedical Sciences, Institute of Advanced Biomedical Sciences, Henan Key Laboratory of Crystalline Molecular Functional Materials, Henan International Joint Laboratory of Tumor Theranostical Cluster Materials, Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
| | - Ben Zhong Tang
- School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology. The Chinese University of Hong Kong Shenzhen, Shenzhen 518172, China
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11
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Shu C, Yang Z, Rajca A. From Stable Radicals to Thermally Robust High-Spin Diradicals and Triradicals. Chem Rev 2023; 123:11954-12003. [PMID: 37831948 DOI: 10.1021/acs.chemrev.3c00406] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2023]
Abstract
Stable radicals and thermally robust high-spin di- and triradicals have emerged as important organic materials due to their promising applications in diverse fields. New fundamental properties, such as SOMO/HOMO inversion of orbital energies, are explored for the design of new stable radicals, including highly luminescent ones with good photostability. A relation with the singlet-triplet energy gap in the corresponding diradicals is proposed. Thermally robust high-spin di- and triradicals, with energy gaps that are comparable to or greater than a thermal energy at room temperature, are more challenging to synthesize but more rewarding. We summarize a number of high-spin di- and triradicals, based on nitronyl nitroxides that provide a relation between the experimental pairwise exchange coupling constant J/k in the high-spin species vs experimental hyperfine coupling constants in the corresponding monoradicals. This relation allows us to identify outliers, which may correspond to radicals where J/k is not measured with sufficient accuracy. Double helical high-spin diradicals, in which spin density is delocalized over the chiral π-system, have been barely explored, with the sole example of such high-spin diradical possessing alternant π-system with Kekulé resonance form. Finally, we discuss a high-spin diradical with electrical conductivity and derivatives of triangulene diradicals.
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Affiliation(s)
- Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Zhimin Yang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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12
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Akkiraju S, Gilley DM, Savoie BM, Boudouris BW. Anomalous magnetoresistance in a nonconjugated radical polymer glass. Proc Natl Acad Sci U S A 2023; 120:e2308741120. [PMID: 37862383 PMCID: PMC10614627 DOI: 10.1073/pnas.2308741120] [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: 05/24/2023] [Accepted: 09/15/2023] [Indexed: 10/22/2023] Open
Abstract
Macromolecules bearing open-shell entities offer unique transport properties for both electronic and spintronic devices. This work demonstrates that, unlike their conjugated polymer counterparts, the charge carriers in radical polymers (i.e., macromolecules with nonconjugated backbones and with stable open-shell sites present at their pendant groups) are singlet cations, which opens significant avenues for manipulating macromolecular design for advanced solid-state transport in these highly transparent conductors. Despite this key point, magnetoresistive effects are present in radical polymer thin films under applied magnetic fields due to the presence of impurity sites in low (i.e., <1%) concentrations. Additionally, thermal annealing of poly(4-glycidyloxy-2,2,6,6- tetramethylpiperidine-1-oxyl) (PTEO), a nonconjugated polymer with stable open-shell pendant groups, facilitated better electron exchange and pairwise spin interactions resulting in an unexpected magnetoresistance signal at relatively low field strengths (i.e., <2 T). The addition of 4-hydroxy-2,2,6,6-tetramethylpiperidin-N-oxy (TEMPO-OH), a paramagnetic species, increased the magnitude of the MR effect when the small molecule was added to the radical polymer matrix. These macroscopic experimental observables are explained using computational approaches that detail the fundamental molecular principles. This intrinsic localized charge transport behavior differs from the current state of the art regarding closed-shell conjugated macromolecules, and it opens an avenue towards next-generation transport in organic electronic materials.
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Affiliation(s)
- Siddhartha Akkiraju
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN47906
| | - Dylan M. Gilley
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN47906
| | - Brett M. Savoie
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN47906
| | - Bryan W. Boudouris
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN47906
- Department of Chemistry, Purdue University, West Lafayette, IN47906
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13
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Zong X, Yang Y, Yin S. The Energy Structure of Spin States in Reducing the Nonradiative Voltage Loss in Organic Solar Cells. J Phys Chem Lett 2023; 14:7490-7497. [PMID: 37581406 DOI: 10.1021/acs.jpclett.3c01918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
In organic solar cells (OSCs), the nonradiative voltage loss (ΔVnr) has been identified as a critical factor for the relatively lower open-circuit voltage. Under open-circuit conditions, most of the charge recombination processes occur via the triplet exciton state, underscoring the importance of the energy structures concerning the local exciton (LE) and charge transfer (CT) spin states. In this Letter, we propose a five-state model to explore the spin state energy structures to reduce ΔVnr. Our calculations reveal that, to minimize ΔVnr, the spin singlet state for LE should possess a lower energy than the triplet state, ES1 < ET1. In contrast, the energies of the CT spin states have a negligible effect on ΔVnr. We identify the best energy structure as ES1 < ET1 ∼ ECT1/CT3. Moreover, our calculations demonstrate that strong couplings between these spin states, particularly involving spin flip, can effectively mitigate ΔVnr. These findings present novel insights for the advancement of OSCs.
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Affiliation(s)
- Xin Zong
- School of Physics, Shandong University, Jinan 250100, People's Republic of China
| | - Yawen Yang
- School of Physics, Shandong University, Jinan 250100, People's Republic of China
| | - Sun Yin
- School of Physics, Shandong University, Jinan 250100, People's Republic of China
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14
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Lu C, Cho E, Cui Z, Gao Y, Cao W, Brédas JL, Coropceanu V, Li F. Towards Efficient and Stable Donor-Acceptor Luminescent Radicals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208190. [PMID: 36417767 DOI: 10.1002/adma.202208190] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/01/2022] [Indexed: 06/16/2023]
Abstract
In contrast to closed-shell luminescent molecules, the electronic ground state and lowest excited state in organic luminescent radicals are both spin doublet, which results in spin-allowed radiative transitions. Most reported luminescent radicals with high photoluminescent quantum efficiency (PLQE) have a donor-acceptor (D-A•) chemical structure where an electron-donating group is covalently attached to an electron-withdrawing radical core (A•). Understanding the main factors that define the efficiency and stability of D-A• type luminescent radicals remains challenging. Here, we designed and synthesized a series of tri(2,4,6-trichlorophenyl)methyl (TTM) radical derivatives with donor substituents varying by their extent of conjugation and their number of imine-type nitrogen atoms. The experimental results suggest that the luminescence efficiency and stability of the radicals are proportional to the degree of conjugation but inversely proportional to the number of imine nitrogen atoms in the substituents. These experimental trends are very well reproduced by density functional theory calculations. The theoretical results indicate that both the luminescence efficiency and radical stability are related to the energy difference between the charge transfer (CT) and local-excitation (LE) states, which decreases as either the number of imine nitrogen atoms in the substituent increases or its conjugation length decreases.
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Affiliation(s)
- Chen Lu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Eunkyung Cho
- Department of Chemistry and Biochemistry, University of Arizona College of Science, Tucson, AZ, 85721-0088, USA
| | - Zhiyuan Cui
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Yuhang Gao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Wenjuan Cao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Jean-Luc Brédas
- Department of Chemistry and Biochemistry, University of Arizona College of Science, Tucson, AZ, 85721-0088, USA
| | - Veaceslav Coropceanu
- Department of Chemistry and Biochemistry, University of Arizona College of Science, Tucson, AZ, 85721-0088, USA
| | - Feng Li
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
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15
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Merschel A, Rottschäfer D, Neumann B, Stammler HG, Ringenberg M, van Gastel M, Demirer TI, Andrada DM, Ghadwal RS. Crystalline Anions Based on Classical N-Heterocyclic Carbenes. Angew Chem Int Ed Engl 2023; 62:e202215244. [PMID: 36398890 PMCID: PMC10107637 DOI: 10.1002/anie.202215244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/18/2022] [Accepted: 11/18/2022] [Indexed: 11/19/2022]
Abstract
Herein, the first stable anions K[SIPrBp ] (4 a-K) and K[IPrBp ] (4 b-K) (SIPrBp =BpC{N(Dipp)CH2 }2 , IPrBp =BpC{N(Dipp)CH}2 ; Bp=4-PhC6 H4 ; Dipp=2,6-iPr2 C6 H3 ) derived from classical N-heterocyclic carbenes (NHCs) (i.e. SIPr and IPr) have been isolated as violet crystalline solids. 4 a-K and 4 b-K are prepared by KC8 reduction of the neutral radicals [SIPrBp ] (3 a) and [IPrBp ] (3 b), respectively. The radicals 3 a and 3 b as well as [Me-IPrBp ] 3 c (Me-IPrBp =BpC{N(Dipp)CMe}2 ) are accessible as crystalline solids on treatment of the respective 1,3-imidazoli(ni)um bromides (SIPrBp )Br (2 a), (IPrBp )Br (2 b), and (Me-IPrBp )Br (2 c) with KC8 . The cyclic voltammograms of 2 a-2 c exhibit two one-electron reversible redox processes in -0.5 to -2.5 V region that correspond to the radicals 3 a-3 c and the anions (4 a-4 c)- . Computational calculations suggest a closed-shell singlet ground state for (4 a-4 c)- with the singlet-triplet energy gap of 17-24 kcal mol-1 .
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Affiliation(s)
- Arne Merschel
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
| | - Dennis Rottschäfer
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany.,Current address: Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Str. 4, Marburg, Germany
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
| | - Mark Ringenberg
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim a. d. Ruhr, Germany
| | - T Ilgin Demirer
- Allgemeine und Anorganische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany
| | - Diego M Andrada
- Allgemeine und Anorganische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany
| | - Rajendra S Ghadwal
- Anorganische Molekülchemie und Katalyse, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
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16
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Hattori Y, Kitajima R, Ota W, Matsuoka R, Kusamoto T, Sato T, Uchida K. The simplest structure of a stable radical showing high fluorescence efficiency in solution: benzene donors with triarylmethyl radicals. Chem Sci 2022; 13:13418-13425. [PMID: 36507177 PMCID: PMC9682904 DOI: 10.1039/d2sc05079j] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 10/24/2022] [Indexed: 12/15/2022] Open
Abstract
Donor-radical acceptor systems have recently attracted much attention as efficient doublet emitters that offer significant advantages for applications such as OLEDs. We employed an alkylbenzene (mesityl group) as the simplest donor to date and added it to a diphenylpyridylmethyl radical acceptor. The (3,5-difluoro-4-pyridyl)bis[2,6-dichloro-4-(2,4,6-trimethylphenyl)phenyl]methyl radical (Mes2F2PyBTM) was prepared in only three steps from commercially available reagents. A stable radical composed of only one pyridine ring, four benzene rings, methyl groups, halogens, and hydrogens showed fluorescence of over 60% photoluminescence quantum yield (PLQY) in chloroform, dichloromethane, and PMMA. The key to high fluorescence efficiency was benzene rings perpendicular to the diphenylpyridylmethyl radical in the doublet ground (D0) state. The relatively low energy of the β-HOMO and the electron-accepting character of the radical enabled the use of benzenes as electron donors. Furthermore, the structural relaxation of the doublet lowest excited (D1) state was minimized by steric hindrance of the methyl groups. The reasons for this high efficiency include the relatively fast fluorescence transition and the slow internal conversion, both of which were explained by the overlap density between the D1 and D0 states.
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Affiliation(s)
- Yohei Hattori
- Materials Chemistry Course, Faculty of Advanced Science and Technology, Ryukoku UniversitySetaOtsuShiga 520-2194Japan
| | - Ryota Kitajima
- Materials Chemistry Course, Faculty of Advanced Science and Technology, Ryukoku UniversitySetaOtsuShiga 520-2194Japan
| | - Wataru Ota
- MOLFEX, Inc.Takano-Nishibiraki-cho 34-4Kyoto 606-8103Japan
| | - Ryota Matsuoka
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science5-1, Higashiyama, MyodaijiOkazakiAichi 444-8787Japan,SOKENDAI (The Graduate University for Advanced Studies)Shonan VillageHayamaKanagawa 240-0193Japan
| | - Tetsuro Kusamoto
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science5-1, Higashiyama, MyodaijiOkazakiAichi 444-8787Japan,SOKENDAI (The Graduate University for Advanced Studies)Shonan VillageHayamaKanagawa 240-0193Japan,JST-PRESTO4-1-8, HonchoKawaguchiSaitama 332-0012Japan
| | - Tohru Sato
- Fukui Institute for Fundamental Chemistry, Kyoto UniversityTakano-Nishibiraki-cho 34-4Kyoto 606-8103Japan,Department of Molecular Engineering, Graduate School of Engineering, Kyoto UniversityNishikyo-kuKyoto 615-8510Japan
| | - Kingo Uchida
- Materials Chemistry Course, Faculty of Advanced Science and Technology, Ryukoku UniversitySetaOtsuShiga 520-2194Japan
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17
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Li X, Wang YL, Chen C, Ren YY, Han YF. A platform for blue-luminescent carbon-centered radicals. Nat Commun 2022; 13:5367. [PMID: 36100595 PMCID: PMC9470563 DOI: 10.1038/s41467-022-33130-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 09/02/2022] [Indexed: 11/26/2022] Open
Abstract
Organic radicals, which have unique doublet spin-configuration, provide an alternative method to overcome the efficiency limitation of organic light-emitting diodes (OLEDs) based on conventional fluorescent organic molecules. Further, they have made great breakthroughs in deep-red and near-infrared OLEDs. However, it is difficult to extend their fluorescence into a short-wavelength region because of the natural narrow bandgap of the organic radicals. Herein, we significantly expand the scope of luminescent radicals by showing a new platform of carbon-centered radicals derived from N-heterocyclic carbenes that produce blue to green emissions (444–529 nm). Time-dependent density functional theory calculations and experimental investigations disclose that the fluorescence originates from the high-energy excited states to the ground state, demonstrating an anti-Kasha behavior. The present work provides an efficient and modular approach toward a library of carbon-centered radicals that feature anti-Kasha’s rule emission, rendering them as potential new emitters in the short-wavelength region. Organic radicals, which have unique doublet spin-configuration, provide an alternative method to overcome the efficiency limitation of organic light-emitting diodes (OLEDs) but extending their fluorescence into a short-wavelength region remains challenging. Here, the authors significantly expand the scope of luminescent radicals by showing a new platform of carbon-centered radicals that produce blue to green emission.
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18
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Steffenfauseweh H, Vishnevskiy YV, Neumann B, Stammler H, Andrada DM, Ghadwal RS. Isolation of an Arsenic Diradicaloid with a Cyclic C 2 As 2 -Core. Angew Chem Int Ed Engl 2022; 61:e202207415. [PMID: 35652361 PMCID: PMC9545666 DOI: 10.1002/anie.202207415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Indexed: 01/08/2023]
Abstract
Herein, we report on the synthesis, characterization, and reactivity studies of the first cyclic C2 As2 -diradicaloid {(IPr)CAs}2 (6) (IPr = C{N(Dipp)CH}2 ; Dipp = 2,6-iPr2 C6 H3 ). Treatment of (IPr)CH2 (1) with AsCl3 affords the Lewis adduct {(IPr)CH2 }AsCl3 (2). Compound 2 undergoes stepwise dehydrochlorination to yield {(IPr)CH}AsCl2 (3) and {(IPr)CAsCl}2 (5 a) or [{(IPr)CAs}2 Cl]OTf (5 b). Reduction of 5 a (or 5 b) with magnesium turnings gives 6 as a red crystalline solid in 90% yield. Compound 6 featuring a planar C2 As2 ring is diamagnetic and exhibits well resolved NMR signals. DFT calculations reveal a singlet ground state for 6 with a small singlet-triplet energy gap of 8.7 kcal mol-1 . The diradical character of 6 amounts to 20% (CASSCF, complete active space self consistent field) and 28% (DFT). Treatments of 6 with (PhSe)2 and Fe2 (CO)9 give rise to {(IPr)CAs(SePh)}2 (7) and {(IPr)CAs}2 Fe(CO)4 (8), respectively.
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Affiliation(s)
- Henric Steffenfauseweh
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
| | - Yury V. Vishnevskiy
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
| | - Beate Neumann
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
| | - Diego M. Andrada
- Faculty of Natural Sciences and TechnologyDepartment of ChemistrySaarland UniversityCampus C4.166123SaarbrückenGermany
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
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19
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Abroshan H, Winget P, Kwak HS, Brown CT, Halls MD. Organic radical emitters: nature of doublet excitons in emissive layers. Phys Chem Chem Phys 2022; 24:16891-16899. [PMID: 35788234 DOI: 10.1039/d2cp00592a] [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
Organic radical emitters have received significant attention as a new route to efficient organic light-emitting diodes (OLEDs). The electronic structure of radical emitters allows bypassing the triplet harvesting issue in current OLED devices. However, the nature of doublet excited states remains elusive due to the complex nature of emissive layers. To date, the computational efforts have treated radical carrying materials as isolated entities in the gas phase. However, OLED materials are applied as thin solid films where intermolecular interactions significantly impact optoelectronic properties of the devices. Here, we combine molecular dynamics simulations and quantum chemical calculations to evaluate the effect of emitter-host interactions on the performance of radical-based emissive layers. Results demonstrate that intermolecular interactions remarkably modulate the electronic properties of the radicals in the thin solid films. The doublet excitons of isolated emitters demonstrate a hybrid character of charge-transfer (CT) and local-excitation (LE), while the emitter-host clusters present a significant CT character. Further, the impact of static and dynamic disorders on the hole-electron recombination is studied. Although the host-emitter interactions simultaneously decrease radiative rates and increase non-radiative rates, the latter rates are 100 times smaller than the former rates, allowing internal quantum efficiency to reach 100% for the doublet-based emission process. The results of this study highlight the significant impact of host-emitter interactions on radiative and non-radiative recombination processes and offer guidelines to tune these interactions for advancing radical-based OLEDs.
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20
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Steffenfauseweh H, Vishnevskiy YV, Neumann B, Stammler HG, Andrada DM, Ghadwal R. Isolation of an Arsenic Diradicaloid with a Cyclic C2As2‐Core. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | | | - Beate Neumann
- Bielefeld University: Universitat Bielefeld Chemistry GERMANY
| | | | - Diego M. Andrada
- Saarland University: Universitat des Saarlandes Chemistry GERMANY
| | - Rajendra Ghadwal
- Universitat Bielefeld Institut für Anorganische Chemie Universitätstrasse 25 33615 Bielefeld GERMANY
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21
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Hou X, Truong Nguyen G, Xu T, Wei H, Seng Herng T, Huo G, Wang D, Ding J, Wu S, Ungur L, Wu J. Stable Triarylmethyl Radicals and Cobalt(II) Ions Based 1D/2D Coordination Polymers. Chemistry 2022; 28:e202200687. [DOI: 10.1002/chem.202200687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Xudong Hou
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
| | - Giang Truong Nguyen
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
| | - Tingting Xu
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
| | - Haipeng Wei
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
| | - Tun Seng Herng
- Department of Materials Science and Engineering National University of Singapore 119260 Singapore Singapore
| | - Guifei Huo
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
| | - Dingguan Wang
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
| | - Jun Ding
- Department of Materials Science and Engineering National University of Singapore 119260 Singapore Singapore
| | - Shaofei Wu
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
| | - Liviu Ungur
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
| | - Jishan Wu
- Department of Chemistry National University of Singapore 3 Science drive 3 117543 Singapore Singapore
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22
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Green JD, Fuemmeler EG, Hele TJH. Inverse molecular design from first principles: tailoring organic chromophore spectra for optoelectronic applications. J Chem Phys 2022; 156:180901. [DOI: 10.1063/5.0082311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The discovery of molecules with tailored optoelectronic properties such as specific frequency and intensity of absorption or emission is a major challenge in creating next-generation organic light-emitting diodes (OLEDs) and photovoltaics. This raises the question: how can we predict a potential chemical structure from these properties? Approaches that attempt to tackle this inverse design problem include virtual screening, active machine learning and genetic algorithms. However, these approaches rely on a molecular database or many electronic structure calculations, and significant computational savings could be achieved if there was prior knowledge of (i) whether the optoelectronic properties of a parent molecule could easily be improved and (ii) what morphing operations on a parent molecule could improve these properties. In this perspective we address both of these challenges from first principles. We firstly adapt the Thomas-Reiche-Kuhn sum rule to organic chromophores and show how this indicates how easily the absorption and emission of a molecule can be improved. We then show how by combining electronic structure theory and intensity borrowing perturbation theory we can predict whether or not the proposed morphing operations will achieve the desired spectral alteration, and thereby derive widely-applicable design rules. We go on to provide proof-of-concept illustrations of this approach to optimizing the visible absorption of acenes and the emission of radical OLEDs. We believe this approach can be integrated into genetic algorithms by biasing morphing operations in favour of those which are likely to be successful, leading to faster molecular discovery and greener chemistry.
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23
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Chen JF, Tian G, Liu K, Zhang N, Wang N, Yin X, Chen P. Pillar[5]arene-based Neutral Radicals with Doublet Red Emissions and Stable Chiroptical Properties. Org Lett 2022; 24:1935-1940. [PMID: 35243861 DOI: 10.1021/acs.orglett.2c00313] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stable organic radicals with unique luminescence show great importance in photoelectromagnetic materials. We herein report two unusual radical-based systems (P5N-TTM and P5B-TTM) using the concerted effects of planar chiral pillar[5]arenes and tris(2,4,6-trichlorophenyl)methyl (TTM) radicals. The steric effect and electronic doublet-spin character of these radicals allowed the optical resolution and the first red emissions (∼650 nm) for pillar[5]arene derivatives. Notably, cross-coupling with macrocyclic pillar[5]arene, in turn, considerably enhanced the configurational stability of TTM radicals.
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Affiliation(s)
- Jin-Fa Chen
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science of the Ministry of Education, Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering of the Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology of China, Beijing 102488, China
| | - Guoqing Tian
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science of the Ministry of Education, Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering of the Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology of China, Beijing 102488, China
| | - Kanglei Liu
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science of the Ministry of Education, Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering of the Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology of China, Beijing 102488, China
| | - Niu Zhang
- Analysis & Testing Centre, Beijing Institute of Technology of China, Beijing 102488, China
| | - Nan Wang
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science of the Ministry of Education, Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering of the Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology of China, Beijing 102488, China
| | - Xiaodong Yin
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science of the Ministry of Education, Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering of the Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology of China, Beijing 102488, China
| | - Pangkuan Chen
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science of the Ministry of Education, Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering of the Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology of China, Beijing 102488, China
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24
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Research Progress on Triarylmethyl Radical-Based High-Efficiency OLED. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27051632. [PMID: 35268732 PMCID: PMC8911689 DOI: 10.3390/molecules27051632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 11/17/2022]
Abstract
Perchlorotrityl radical (PTM), tris (2,4,6-trichlorophenyl) methyl radical (TTM), (3,5-dichloro-4-pyridyl) bis (2,4,6 trichlorophenyl) methyl radical (PyBTM), (N-carbazolyl) bis (2,4,6-trichlorophenyl) methyl radical (CzBTM), and their derivatives are stable organic radicals that exhibit light emissions at room temperature. Since these triarylmethyl radicals have an unpaired electron, their electron spins at the lowest excited state and ground state are both doublets, and the transition from the lowest excited state to the ground state does not pose the problem of a spin-forbidden reaction. When used as OLED layers, these triarylmethyl radicals exhibit unique light-emitting properties, which can increase the theoretical upper limit of the OLED’s internal quantum efficiency (IQE) to 100%. In recent years, research on the luminescent properties of triarylmethyl radicals has attracted increasing attention. In this review, recent developments in these triarylmethyl radicals and their derivatives in OLED devices are introduced.
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25
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Ghadwal RS. Tuning the Electronic Properties of Main-Group Species by N-Heterocyclic Vinyl (NHV) Scaffolds. Acc Chem Res 2022; 55:457-470. [PMID: 35042327 DOI: 10.1021/acs.accounts.1c00701] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ConspectusMolecules and materials with easily tunable electronic structures and properties are at the forefront of contemporary research. π-Conjugation is fundamental in organic chemistry and plays a key role in the design of molecular materials. In this Account, we showcase the applicability of N-heterocyclic vinyl (NHV) substituents based on classical N-heterocyclic carbenes (NHCs) for tuning the structure, properties, and stability of main-group species (E) via π-conjugation and/or π-donation.NHVs such as [(NHC)═CR] (R = H or aryl) are monoanionic ligands formally derived by the deprotonation of N-heterocyclic olefins (NHOs), (NHC)═CHR. Further deprotonation of [(NHC)═CR] (R = H) is viable, giving rise to N-heterocyclic vinylidene (NHVD) species such as (NHC)═C. NHVs and NHVDs feature a highly polarizable exocyclic CNHC═C bond because of the presence of adjacent π-donor nitrogen atoms. The nature of the NHC, in particular the π-acceptor property, has a direct consequence on the polarity of the CNHC═C bond and hence on the magnitude of π-conjugation in the derived molecules. Thus, the electronic structure, especially the energy and shape of frontier molecular orbitals, HOMO and LUMO, of derived species can be fine-tuned by a judicious choice of the carbene unit. For instance, the HOMO of classical diphosphenes (RP═PR) (R = alkyl or aryl) is invariably the phosphorus lone-pair orbital, while the P═P π-bond is HOMO - 1 or HOMO - 2. In strong contrast, the HOMO of divinyldiphosphenes (R = NHV) is mainly the P═P π-bond. This is owing to the π-conjugation, resulting in the lowering of the LUMO and raising of the HOMO energy. They have a remarkably small HOMO-LUMO energy gap (4.15-4.50 eV) and readily undergo 1e-oxidations, giving rise to stable radical cations and dications.By employing a similar approach, one can access divinyldiarsenes and the corresponding radical cations and dications as crystalline solids. The use of divinyldiphosphenes and divinyldiarsenes as promising ligands in the stabilization of metalloradicals has been shown. By a logical selection of singlet carbenes, stable 2-phosha-1,3-butadiene and 2-arsa-1,3-butadiene compounds, as well as related radical cations and dications, can be prepared as crystalline solids.The relevance of NHV ligands as potent π-donors has been demonstrated for the stabilization of elusive electrophilic phosphinidene and arsinidene complexes {(NHV)E}Fe(CO)4 (E = P or As). Moreover, stable singlet diradicaloid [(NHC)CP]2 and p-quinodimethane derivatives [(NHC)CP2]2 based on an NHVD framework are accessible as stable solids.In this Account, a special emphasis is given to the contributions from this laboratory. The author hopes that this Account will serve as a useful reference guide for researchers interested in studying and applying NHV and NHVD scaffolds in modern molecular chemistry and materials sciences.
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Affiliation(s)
- Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
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26
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Liu Y, Zheng Z, Coropceanu V, Brédas JL, Ginger DS. Lower limits for non-radiative recombination loss in organic donor/acceptor complexes. MATERIALS HORIZONS 2022; 9:325-333. [PMID: 34842253 DOI: 10.1039/d1mh00529d] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Understanding the factors controlling radiative and non-radiative transition rates for charge transfer states in organic systems is important for applications ranging from organic photovoltaics (OPV) to lasers and LEDs. We explore the role of charge-transfer (CT) energetics, lifetimes, and photovoltaic properties in the limit of very slow non-radiative rates by using a model donor/acceptor system with photoluminescence dominated by thermally activated delayed fluorescence (TADF). This blend exhibits an extremely high photoluminescence quantum efficiency (PLQY = ∼22%) and comparatively long PL lifetime, while simultaneously yielding appreciable amounts of free charge generation (photocurrent external quantum efficiency EQE of 24%). In solar cells, this blend exhibits non-radiative voltage losses of only ∼0.1 V, among the lowest reported for an organic system. Notably, we find that the non-radiative decay rate, knr, is on the order of 105 s-1, approximately 4-5 orders of magnitude slower than typical OPV blends, thereby confirming that high radiative efficiency and low non-radiative voltage losses are achievable by reducing knr. Furthermore, despite the high radiative efficiency and already comparatively slow knr, we find that knr is nevertheless much faster than predicted by Marcus-Levich-Jortner two-state theory and we conclude that CT-local exciton (LE) hybridization is present. Our findings highlight that it is crucial to evaluate how radiative and non-radiative rates of the LE states individually influence the PLQY of charge-transfer states, rather than solely focusing on the PLQY of the LE. This conclusion will guide material selection in achieving low non-radiative voltage loss in organic solar cells and high luminescence efficiency in organic LEDs.
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Affiliation(s)
- Yun Liu
- Department of Chemistry, University of Washington, Seattle, WA, 98195-2120, USA.
| | - Zilong Zheng
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400, USA
- College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
| | - Veaceslav Coropceanu
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400, USA
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721-0088, USA
| | - Jean-Luc Brédas
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400, USA
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721-0088, USA
| | - David S Ginger
- Department of Chemistry, University of Washington, Seattle, WA, 98195-2120, USA.
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27
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Zhou HP, Wu SX, Duan YC, Gao FW, Pan QQ, Kan YH, Su ZM. A theoretical study on the donor ability adjustment of tris(2,4,6-trichlorophenyl)methyl-triarylamine (TTM-TPA) radicals aiming to develop better organic luminescent materials. NEW J CHEM 2022. [DOI: 10.1039/d2nj01548j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spin-unrestricted DFT and spin-unrestricted TDDFT calculations were performed to systematically investigate the correlation between the electron donating ability of donors and photophysical properties in D–A luminescent radicals.
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Affiliation(s)
- Hai-Ping Zhou
- Key Laboratory of Electrochemical Energy Storage and Energy Conversion of Hainan Province, School of Chemistry & Chemical Engineering, Hainan Normal University, Haikou 571158, China
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
| | - Shui-Xing Wu
- Key Laboratory of Electrochemical Energy Storage and Energy Conversion of Hainan Province, School of Chemistry & Chemical Engineering, Hainan Normal University, Haikou 571158, China
| | - Ying-Chen Duan
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
| | - Feng-Wei Gao
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
| | - Qing-Qing Pan
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
| | - Yu-He Kan
- Jiangsu Province Key Laboratory for Chemistry of Low-Dimensional Materials, School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huai'an 223300, China
| | - Zhong-Min Su
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China
- Institute of Functional Material Chemistry, Faculty of Chemistry & National & Local United Engineering Laboratory for Power Battery, Northeast Normal University, Changchun 130024, China
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28
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Zhou HP, Wu SX, Duan YC, Gao FW, Pan QQ, Kan YH, Su ZM. The combination of skeleton-engineering and periphery-engineering: a design strategy for organic doublet emitters. Phys Chem Chem Phys 2022; 24:26853-26862. [DOI: 10.1039/d2cp03948f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A series of radicals based on tris(2,4,6-trichlorophenyl)methyl (TTM) were theoretically designed and evaluated by combining skeleton-engineering and periphery-engineering strategies.
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Affiliation(s)
- Hai-Ping Zhou
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, Changchun 130012, China
| | - Shui-Xing Wu
- Key Laboratory of Electrochemical Energy Storage and Energy Conversion of Hainan Province, School of Chemistry & Chemical Engineering, Hainan Normal University, Haikou 571158, China
| | - Ying-Chen Duan
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, Changchun 130012, China
| | - Feng-Wei Gao
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, Changchun 130012, China
| | - Qing-Qing Pan
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, Changchun 130012, China
| | - Yu-He Kan
- Jiangsu Province Key Laboratory for Chemistry of Low-Dimensional Materials, School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huai’an 223300, China
| | - Zhong-Min Su
- School of Chemistry and Environmental Engineering, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Changchun University of Science and Technology, Changchun 130012, China
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130021, China
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29
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Hattori Y, Tsubaki S, Matsuoka R, Kusamoto T, Nishihara H, Uchida K. Expansion of Photostable Luminescent Radicals by Meta-Substitution. Chem Asian J 2021; 16:2538-2544. [PMID: 34270166 DOI: 10.1002/asia.202100612] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/15/2021] [Indexed: 11/12/2022]
Abstract
Polychlorinated pyridyldiphenylmethyl radicals having substituents meta to the position bearing the carbon-centered radical (α-carbon) are synthesized. All of them are stable in ambient conditions in solutions and fluorescent in cyclohexane. The fluorescence of the radicals with bromo, phenyl, 4-chlorophenyl, or 2-pyridyl substituents are enhanced in chloroform, while the emission of the radicals with 2-thienyl or 2-furyl substituents are quenched in chloroform. DFT and TD-DFT calculations indicate that the first doublet excited states of the former are locally excited, while the first doublet excited states of the latter are charge transfer states from the π-electron-donating substituent to the accepting radical. The latter also show much higher photostability under 370-nm light irradiation compared with the first reported photostable fluorescent radical, (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radical (PyBTM), with pronounced bathochromic shifts of the fluorescence.
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Affiliation(s)
- Yohei Hattori
- Materials Chemistry Course, Faculty of Advanced Science and Technology, Ryukoku University, Seta, Otsu, Shiga, 520-2194, Japan
| | - Shunsuke Tsubaki
- Materials Chemistry Course, Faculty of Advanced Science and Technology, Ryukoku University, Seta, Otsu, Shiga, 520-2194, Japan
| | - Ryota Matsuoka
- Department of Life and Coordination-Complex Molecular Science, Instite for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Tetsuro Kusamoto
- Department of Life and Coordination-Complex Molecular Science, Instite for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Hiroshi Nishihara
- Research Institute for Science and Technology, Tokyo University of Science, 2641, Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Kingo Uchida
- Materials Chemistry Course, Faculty of Advanced Science and Technology, Ryukoku University, Seta, Otsu, Shiga, 520-2194, Japan
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30
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Rajca A, Shu C, Zhang H, Zhang S, Wang H, Rajca S. Thiophene-Based Double Helices: Radical Cations with SOMO-HOMO Energy Level Inversion †. Photochem Photobiol 2021; 97:1376-1390. [PMID: 34152605 DOI: 10.1111/php.13475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/17/2021] [Indexed: 11/29/2022]
Abstract
We report relatively persistent, open-shell thiophene-based double helices, radical cations 1•+ -TMS12 and 2•+ -TMS8 . Closed-shell neutral double helices, 1-TMS12 and 2-TMS8 , have nearly identical first oxidation potentials, E+/0 ≈ +1.33 V, corresponding to reversible oxidation to their radical cations. The radical cations are generated, using tungsten hexachloride in dichloromethane (DCM) as an oxidant, E+/0 ≈ +1.56 V. EPR spectra consist of a relatively sharp singlet peak with an unusually low g-value of 2.001-2.002, thus suggesting exclusive delocalization of spin density over π-conjugated system consisting of carbon atoms only. DFT computations confirm these findings, as only negligible fraction of spin density is found on sulfur and silicon atoms and the spin density is delocalized over a single tetrathiophene moiety. For radical cation, 1•+ -TMS12 , energy level of the singly occupied molecular orbital (SOMO) lies below the four highest occupied molecular orbitals (HOMOs), thus indicating the SOMO-HOMO inversion (SHI) and therefore, violating the Aufbau principle. 1•+ -TMS12 has a half-life of the order of only 5 min at room temperature. EPR peak intensity of 2•+ -TMS8 , which does not show SHI, is practically unchanged over at least 2 h.
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Affiliation(s)
- Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE, USA
| | - Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, NE, USA
| | - Hui Zhang
- Department of Chemistry, University of Nebraska, Lincoln, NE, USA
| | - Sheng Zhang
- Engineering Research Center for Nanomaterials, Henan University, Kaifeng, China
| | - Hua Wang
- Engineering Research Center for Nanomaterials, Henan University, Kaifeng, China
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE, USA
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31
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Medina Rivero S, Shang R, Hamada H, Yan Q, Tsuji H, Nakamura E, Casado J. Non-Aufbau Spiro-Conjugated Quinoidal & Aromatic Charged Radicals. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20200385] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Samara Medina Rivero
- Department of Physical Chemistry, Faculty of Science, University of Málaga, Campus de Teatinos, s/n, 29071 Málaga, Spain
| | - Rui Shang
- Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hiroyoshi Hamada
- Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
| | - Qifan Yan
- Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hayato Tsuji
- Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
- Department of Chemistry, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
| | - Eiichi Nakamura
- Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
| | - Juan Casado
- Department of Physical Chemistry, Faculty of Science, University of Málaga, Campus de Teatinos, s/n, 29071 Málaga, Spain
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32
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Murata R, Wang Z, Abe M. Singly Occupied Molecular Orbital−Highest Occupied Molecular Orbital (SOMO−HOMO) Conversion. Aust J Chem 2021. [DOI: 10.1071/ch21186] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Singly occupied molecular orbital−highest occupied molecular orbital (SOMO−HOMO) conversion (inversion), SHC, is a phenomenon in which the SOMO is lower in energy than the doubly occupied molecular orbitals (DOMO, HOMO). A non-Aufbau electronic structure leads to unique properties such as a switch in bond dissociation energy and the generation of high-spin species on one-electron oxidation. In addition, the pronounced photostability of these species has been reported recently for application in organic light-emitting devices. In this review article, we summarise the chemistry of SOMO−HOMO converted (inverted) species reported to date.
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