1
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Zhou L, Feng RR, Zhang W, Gai F. Triple-Bond Vibrations: Emerging Applications in Energy and Biological Sciences. J Phys Chem Lett 2024; 15:187-200. [PMID: 38156972 DOI: 10.1021/acs.jpclett.3c02619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Triple bonds, such as that formed between two carbon atoms (i.e., C≡C) or that formed between one carbon atom and one nitrogen atom (i.e., C≡N), afford unique chemical bonding and hence vibrational characteristics. As such, they are not only frequently used to construct molecules with tailored chemical and/or physical properties but also employed as vibrational probes to provide site-specific chemical and/or physical information at the molecular level. Herein, we offer our perspective on the emerging applications of various triple-bond vibrations in energy and biological sciences with a focus on C≡C and C≡N triple bonds.
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Affiliation(s)
- Liang Zhou
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Ran-Ran Feng
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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2
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Kim J, Teo HT, Hong Y, Liau YC, Yim D, Han Y, Oh J, Kim H, Chi C, Kim D. Leveraging Charge-Transfer Interactions in Through-Space-Coupled Pentacene Dendritic Oligomer for Singlet Exciton Fission. J Am Chem Soc 2023; 145:19812-19823. [PMID: 37656929 DOI: 10.1021/jacs.3c05660] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/03/2023]
Abstract
Singlet exciton fission in organic chromophores has received much attention during the past decade. Inspired by numerous spectroscopic studies in the solid state, there have been vigorous efforts to study singlet exciton fission dynamics in covalently bonded oligomers, which aims to investigate underlying mechanisms of this intriguing process in simplified model systems. In terms of through-space orbital interactions, however, most of covalently bonded pentacene oligomers studied so far fall into weakly interacting systems since they manifest chain-like structures based on various (non)conjugated linkers. Therefore, it remains as a compelling question to answer how through-space interactions in the solid state intervene this photophysical process since it is hypersensitive to displacements and orientations between neighboring chromophores. Herein, as one of experimental studies to answer this question, we introduced a tight-packing dendritic structure whose mesityl-pentacene constituents are coupled via moderate through-space orbital interactions. Based on the comparison with a suitably controlled dendritic structure, which is in a weak coupling regime, important mechanistic viewpoints are tackled such as configurational mixings between singlet, charge-transfer, and triplet pair states and the role of chromophore multiplication. We underscore that our through-space-coupled dendritic oligomer in a quasi-intermediate coupling regime provides a hint on the interplay of multiconfigurational excited-states, which might have drawn complexity in singlet exciton fission kinetics throughout numerous solid-state morphologies.
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Affiliation(s)
- Juno Kim
- Department of Chemistry, Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul 03722, Korea
| | - Hao Ting Teo
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Yongseok Hong
- Department of Chemistry, Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul 03722, Korea
| | - Yuan Cheng Liau
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Daniel Yim
- Department of Chemistry, Incheon National University, Incheon 22012, Korea
| | - Yi Han
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Juwon Oh
- Department of ICT Environmental Health System and Department of Chemistry, Soonchunhyang University, Asan 31538, Korea
| | - Hyungjun Kim
- Department of Chemistry, Incheon National University, Incheon 22012, Korea
| | - Chunyan Chi
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Dongho Kim
- Department of Chemistry, Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul 03722, Korea
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3
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Stuart AN, Tapping P, Kee T, Huang DM. Pitfalls of quantifying intersystem crossing rates in singlet-fission chromophore solutions. J Chem Phys 2022; 157:084312. [DOI: 10.1063/5.0100619] [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
Singlet fission (SF), a process that produces two triplet excitons from one singlet exciton, has attracted recent interest for its potential to circumvent the detailed-balance efficiency limit of single-junction solar cells. For the potential of SF to be fully realized, accurate assignment and quantification of SF is necessary. Intersystem crossing (ISC) is another process of singlet to triplet conversion that is important to distinguish from SF to avoid either over- or under-estimation of SF triplet production. Here, we quantify an upper bound on the rate of ISC in two commonly studied SF chromophores, TIPS-pentacene and TIPS-tetracene, by using transient absorption spectroscopy of solutions of varying concentrations in toluene. We show that SF in solutions of these acenes has previously been misidentified as ISC, and vice versa. By determining a bimolecular SF rate constant in concentrated solutions in which SF dominates over ISC, we distinguish triplet formation due to SF from triplet formation due to ISC, and show that the characteristic time scale of ISC must be longer than 325 ns in TIPS-pentacene, while it must be longer than 118 ns in TIPS-tetracene. We additionally note that no excimer formation is observed in the relatively dilute (up to 8 mM) solutions studied here, indicating that previous excimer formation observed at much higher concentrations may be partially due to aggregate formation. This work highlights that an accurate quantification of ISC is crucial as it leads to accurate determination of SF rate constants and yields.
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Affiliation(s)
| | | | - Tak Kee
- Chemistry, The University of Adelaide Faculty of Sciences, Australia
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4
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Pensack RD, Purdum GE, Mazza SM, Grieco C, Asbury JB, Anthony JE, Loo YL, Scholes GD. Excited-State Dynamics of 5,14- vs 6,13-Bis(trialkylsilylethynyl)-Substituted Pentacenes: Implications for Singlet Fission. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:9784-9793. [PMID: 35756579 PMCID: PMC9210346 DOI: 10.1021/acs.jpcc.2c00897] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 05/20/2022] [Indexed: 05/16/2023]
Abstract
Singlet fission is a process in conjugated organic materials that has the potential to considerably improve the performance of devices in many applications, including solar energy conversion. In any application involving singlet fission, efficient triplet harvesting is essential. At present, not much is known about molecular packing arrangements detrimental to singlet fission. In this work, we report a molecular packing arrangement in crystalline films of 5,14-bis(triisopropylsilylethynyl)-substituted pentacene, specifically a local (pairwise) packing arrangement, responsible for complete quenching of triplet pairs generated via singlet fission. We first demonstrate that the energetic condition necessary for singlet fission is satisfied in amorphous films of the 5,14-substituted pentacene derivative. However, while triplet pairs form highly efficiently in the amorphous films, only a modest yield of independent triplets is observed. In crystalline films, triplet pairs also form highly efficiently, although independent triplets are not observed because triplet pairs decay rapidly and are quenched completely. We assign the quenching to a rapid nonadiabatic transition directly to the ground state. Detrimental quenching is observed in crystalline films of two additional 5,14-bis(trialkylsilylethynyl)-substituted pentacenes with either ethyl or isobutyl substituents. Developing a better understanding of the losses identified in this work, and associated molecular packing, may benefit overcoming losses in solids of other singlet fission materials.
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Affiliation(s)
- Ryan D. Pensack
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Geoffrey E. Purdum
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Samuel M. Mazza
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Christopher Grieco
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - John B. Asbury
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - John E. Anthony
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Yueh-Lin Loo
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
- Andlinger
Center for Energy and the Environment, Princeton
University, Princeton, New Jersey 08544, United States
| | - Gregory D. Scholes
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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5
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Bera K, Douglas CJ, Frontiera RR. Femtosecond stimulated Raman spectroscopy - guided library mining leads to efficient singlet fission in rubrene derivatives. Chem Sci 2021; 12:13825-13835. [PMID: 34760168 PMCID: PMC8549787 DOI: 10.1039/d1sc04251c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 09/22/2021] [Indexed: 12/04/2022] Open
Abstract
Chromophores undergoing singlet fission are promising candidates for harnessing solar energy as they can generate a pair of charge carriers by the absorption of one photon. However, photovoltaic devices employing singlet fission are still lacking practical applications due to the limitations within the existing molecules undergoing singlet fission. Chemical modifications to acenes can lead to efficient singlet fission devices, but the influence of changes to molecular structure on the rate of singlet fission is challenging to model and predict. Using femtosecond stimulated Raman spectroscopy we have previously demonstrated that the triplet separation process during singlet fission in crystalline rubrene is associated with the loss of electron density from its tetracene core. Based on this knowledge, we mined a library of new rubrene derivatives with electron withdrawing substituents that prime the molecules for efficient singlet fission, without impacting their crystal packing. Our rationally chosen crystalline chromophores exhibit significantly improved singlet fission rates. This study demonstrates the utility and strength of a structurally sensitive spectroscopic technique in providing insights to spectroscopy-guided materials selection and design guidelines that go beyond energy arguments to design new singlet fission-capable chromophores. In the race to find efficient singlet fission materials, picking a winner is not easy. Femtosecond stimulated Raman spectroscopy can help us choose the best candidates, as demonstrated here in choosing from a library of rubrene derivatives.![]()
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Affiliation(s)
- Kajari Bera
- Department of Chemistry, University of Minnesota Minneapolis MN 55455 USA +1612-624-2501
| | - Christopher J Douglas
- Department of Chemistry, University of Minnesota Minneapolis MN 55455 USA +1612-624-2501
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota Minneapolis MN 55455 USA +1612-624-2501
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6
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Kennehan ER, Munson KT, Grieco C, Doucette GS, Marshall AR, Beard MC, Asbury JB. Influence of Ligand Structure on Excited State Surface Chemistry of Lead Sulfide Quantum Dots. J Am Chem Soc 2021; 143:13824-13834. [PMID: 34420309 DOI: 10.1021/jacs.1c06248] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The ligand-nanocrystal boundaries of colloidal quantum dots (QDs) mediate the primary energy and electron transfer processes that underpin photochemical and photocatalytic transformations at their surfaces. We use mid-infrared transient absorption spectroscopy to reveal the influence that ligand structure and bonding to nanocrystal surfaces have on the changes of the excited state surface chemistry of this boundary in PbS QDs and the corresponding impact on charge transfer processes between nanocrystals. We demonstrate that oleate ligands undergo marked changes in their bonding to surfaces in the excitonic excited states of the nanocrystals, indicating that oleate passivated PbS surfaces undergo significant structural changes following photoexcitation. These changes can impact the surface mobility of the ligands and the ability of redox shuttles to approach the nanocrystal surfaces to undergo charge transfer in photocatalytic reactions. In contrast, markedly different transient vibrational features are observed in iodide/mercaptoproprionic acid passivated PbS QD films that result from charge transfer between neighboring nanocrystals and localization of holes at the nanocrystal surfaces near MPA ligands. This ability to distinguish the influence that excitonic excited states vs charge transfer processes have on the surface chemistry of the ligand-nanocrystal boundary lays the groundwork for exploration of how this boundary can be understood and controlled for the design of nanocrystalline materials tailored for specific applications in solar energy harvesting and photocatalytic reactions.
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Affiliation(s)
- Eric R Kennehan
- Magnitude Instruments, State College, Pennsylvania 16803, United States.,Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Kyle T Munson
- Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Christopher Grieco
- Magnitude Instruments, State College, Pennsylvania 16803, United States.,Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Grayson S Doucette
- Intercollege Materials Science and Engineering Program, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ashley R Marshall
- Chemical and Materials Science, National Renewable Energy Laboratory (NREL), Golden, Colorado 80401, United States.,Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Matthew C Beard
- Chemical and Materials Science, National Renewable Energy Laboratory (NREL), Golden, Colorado 80401, United States.,Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - John B Asbury
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.,Intercollege Materials Science and Engineering Program, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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7
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Zeiser C, Moretti L, Reicherter F, Bettinger HF, Maiuri M, Cerullo G, Broch K. Singlet Fission in Dideuterated Tetracene and Pentacene. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202000284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Clemens Zeiser
- Institute for Applied Physics University of Tübingen Auf der Morgenstelle 10 72076 Tübingen Germany
| | - Luca Moretti
- IFN-CNR Dipartimento di Fisica Politecnico di Milano Piazza Leonardo da Vinci 32 20133 Milan Italy
| | - Florian Reicherter
- Institute for Organic Chemistry University of Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Holger F. Bettinger
- Institute for Organic Chemistry University of Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Margherita Maiuri
- IFN-CNR Dipartimento di Fisica Politecnico di Milano Piazza Leonardo da Vinci 32 20133 Milan Italy
| | - Giulio Cerullo
- IFN-CNR Dipartimento di Fisica Politecnico di Milano Piazza Leonardo da Vinci 32 20133 Milan Italy
| | - Katharina Broch
- Institute for Applied Physics University of Tübingen Auf der Morgenstelle 10 72076 Tübingen Germany
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8
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Abstract
Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states. As such, it constitutes an exciton multiplication generation process, which is currently at the focal point for future integration into solar energy conversion devices. Beyond this, various other exciting applications were proposed, including quantum cryptography or organic light emitting diodes. Also, the mechanistic understanding evolved rapidly during the last year. Unfortunately, the number of suitable SF-chromophores is still limited. This is per se problematic, considering the wide range of envisaged applicability. With that in mind, we emphasize uncommon SF-scaffolds and outline requirements as well as strategies to expand the chromophore pool of SF-materials.
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Affiliation(s)
- Tobias Ullrich
- Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Department für Chemie und Pharmazie, Egerlandstr. 1-3, 91058 Erlangen, Germany.
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9
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Zhao X, Bae YJ, Chen M, Harvey SM, Lin C, Zhou J, Schaller RD, Young RM, Wasielewski MR. Singlet fission in core-linked terrylenediimide dimers. J Chem Phys 2020; 153:244306. [PMID: 33380082 DOI: 10.1063/5.0026254] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Xingang Zhao
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Youn Jue Bae
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Michelle Chen
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Samantha M. Harvey
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Chenjian Lin
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Jiawang Zhou
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Richard D. Schaller
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Ryan M. Young
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Michael R. Wasielewski
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, USA
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10
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Kobori Y, Fuki M, Nakamura S, Hasobe T. Geometries and Terahertz Motions Driving Quintet Multiexcitons and Ultimate Triplet–Triplet Dissociations via the Intramolecular Singlet Fissions. J Phys Chem B 2020; 124:9411-9419. [DOI: 10.1021/acs.jpcb.0c07984] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yasuhiro Kobori
- Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Masaaki Fuki
- Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Shunta Nakamura
- Department of Chemistry, Faculty of Science and Technology, Keio University, Yokohama, 223-8522, Japan
| | - Taku Hasobe
- Department of Chemistry, Faculty of Science and Technology, Keio University, Yokohama, 223-8522, Japan
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11
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Cassabaum AA, Bera K, Rich CC, Nebgen BR, Kwang SY, Clapham ML, Frontiera RR. Femtosecond stimulated Raman spectro-microscopy for probing chemical reaction dynamics in solid-state materials. J Chem Phys 2020; 153:030901. [DOI: 10.1063/5.0009976] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Alyssa A. Cassabaum
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Kajari Bera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Christopher C. Rich
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Bailey R. Nebgen
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Siu Yi Kwang
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Margaret L. Clapham
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Renee R. Frontiera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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12
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Kwang SY, Frontiera RR. Spatially Offset Femtosecond Stimulated Raman Spectroscopy: Observing Exciton Transport through a Vibrational Lens. J Phys Chem Lett 2020; 11:4337-4344. [PMID: 32427490 DOI: 10.1021/acs.jpclett.0c01114] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
To design better molecular electronic devices, we need a strong understanding of how charges or excitons propagate, as many efficiency losses arise during transport. Exciton transport has been difficult to study because excitons tend to be short-lived, have short diffusion lengths, and can easily recombine. Here, we debut spatially offset femtosecond stimulated Raman spectroscopy (SO-FSRS), a three-pulse ultrafast microscopy technique. By offsetting the photoexcitation beam, we can monitor Raman spectral changes as a function of both time and position. We used SO-FSRS on 6,13-bis(triisopropylsilylethynyl) pentacene, a well-studied organic semiconductor used in photovoltaics and field-effect transistors. We demonstrated that the fast exciton and free charge carrier transport axes are identical and observed that exciton transport is less anisotropic by a factor of ∼3. SO-FSRS is the first technique that directly tracks molecular structural evolution during exciton transport, which can provide roadmaps for tailor-making molecules for specific electronic devices.
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Affiliation(s)
- Siu Yi Kwang
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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13
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Kennehan ER, Munson KT, Doucette GS, Marshall AR, Beard MC, Asbury JB. Dynamic Ligand Surface Chemistry of Excited PbS Quantum Dots. J Phys Chem Lett 2020; 11:2291-2297. [PMID: 32131595 DOI: 10.1021/acs.jpclett.0c00539] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The ligand shell around colloidal quantum dots mediates the electron and energy transfer processes that underpin their use in optoelectronic and photocatalytic applications. Here, we show that the surface chemistry of carboxylate anchoring groups of oleate ligands passivating PbS quantum dots undergoes significant changes when the quantum dots are excited to their excitonic states. We directly probe the changes of surface chemistry using time-resolved mid-infrared spectroscopy that records the evolution of the vibrational frequencies of carboxylate groups following excitation of the electronic states. The data reveal a reduction of the Pb-O coordination of carboxylate anchoring groups to lead atoms at the quantum dot surfaces. The dynamic surface chemistry of the ligands may increase their surface mobility in the excited state and enhance the ability of molecular species to penetrate the ligand shell to undergo energy and charge transfer processes that depend sensitively on distance.
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Affiliation(s)
- Eric R Kennehan
- Magnitude Instruments, State College, Pennsylvania 16803, United States
| | - Kyle T Munson
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Grayson S Doucette
- Intercollege Materials Science and Engineering Program, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ashley R Marshall
- Chemical and Materials Science, National Renewable Energy Laboratory (NREL), Golden, Colorado 80401, United States
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Matthew C Beard
- Chemical and Materials Science, National Renewable Energy Laboratory (NREL), Golden, Colorado 80401, United States
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - John B Asbury
- Magnitude Instruments, State College, Pennsylvania 16803, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Intercollege Materials Science and Engineering Program, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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14
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Matsuda S, Oyama S, Kobori Y. Electron spin polarization generated by transport of singlet and quintet multiexcitons to spin-correlated triplet pairs during singlet fissions. Chem Sci 2020; 11:2934-2942. [PMID: 34122794 PMCID: PMC8157521 DOI: 10.1039/c9sc04949e] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Singlet fission (SF) is expected to exceed the Shockley–Queisser theoretical limit of efficiency of organic solar cells. Transport of spin-entanglement in the triplet–triplet pair state via one singlet exciton is a promising phenomenon for several energy conversion applications including quantum information science. However, direct observation of electron spin polarization by transport of entangled spin-states has not been presented. In this study, time-resolved electron paramagnetic resonance has been utilized to observe the transportation of singlet and quintet characters generating correlated triplet–triplet (T + T) exciton-pair states by probing the electron spin polarization (ESP) generated in thin films of 6,13-bis(triisopropylsilylethynyl)pentacene. We have clearly demonstrated that the ESP detected at the resonance field positions of individual triplet excitons is dependent on the morphology and on the detection delay time after laser flash to cause SF. ESP was clearly explained by quantum superposition of singlet–triplet–quintet wavefunctions via picosecond triplet-exciton dissociation as the electron spin polarization transfer from strongly exchange-coupled singlet and quintet TT states to weakly-coupled spin-correlated triplet pair states. Although the coherent superposition of spin eigenstates was not directly detected, the present interpretation of the spin correlation of the separated T + T exciton pair may pave new avenues not only for elucidating the vibronic role in the de-coupling between two excitons but also for scalable quantum information processing using quick T + T dissociation via one-photon excitation. Singlet fission (SF) is expected to exceed the Shockley–Queisser theoretical limit of efficiency of organic solar cells.![]()
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Affiliation(s)
- Saki Matsuda
- Department of Chemistry, Graduate School of Science, Kobe University 1-1 Rokkodai-cho, Nada-ku Kobe 657-8501 Japan
| | - Shinya Oyama
- Department of Chemistry, Graduate School of Science, Kobe University 1-1 Rokkodai-cho, Nada-ku Kobe 657-8501 Japan
| | - Yasuhiro Kobori
- Department of Chemistry, Graduate School of Science, Kobe University 1-1 Rokkodai-cho, Nada-ku Kobe 657-8501 Japan .,Molecular Photoscience Research Center, Kobe University 1-1 Rokkodai-cho, Nada-ku Kobe 657-8501 Japan
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15
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Nelson TR, White AJ, Bjorgaard JA, Sifain AE, Zhang Y, Nebgen B, Fernandez-Alberti S, Mozyrsky D, Roitberg AE, Tretiak S. Non-adiabatic Excited-State Molecular Dynamics: Theory and Applications for Modeling Photophysics in Extended Molecular Materials. Chem Rev 2020; 120:2215-2287. [PMID: 32040312 DOI: 10.1021/acs.chemrev.9b00447] [Citation(s) in RCA: 198] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Optically active molecular materials, such as organic conjugated polymers and biological systems, are characterized by strong coupling between electronic and vibrational degrees of freedom. Typically, simulations must go beyond the Born-Oppenheimer approximation to account for non-adiabatic coupling between excited states. Indeed, non-adiabatic dynamics is commonly associated with exciton dynamics and photophysics involving charge and energy transfer, as well as exciton dissociation and charge recombination. Understanding the photoinduced dynamics in such materials is vital to providing an accurate description of exciton formation, evolution, and decay. This interdisciplinary field has matured significantly over the past decades. Formulation of new theoretical frameworks, development of more efficient and accurate computational algorithms, and evolution of high-performance computer hardware has extended these simulations to very large molecular systems with hundreds of atoms, including numerous studies of organic semiconductors and biomolecules. In this Review, we will describe recent theoretical advances including treatment of electronic decoherence in surface-hopping methods, the role of solvent effects, trivial unavoided crossings, analysis of data based on transition densities, and efficient computational implementations of these numerical methods. We also emphasize newly developed semiclassical approaches, based on the Gaussian approximation, which retain phase and width information to account for significant decoherence and interference effects while maintaining the high efficiency of surface-hopping approaches. The above developments have been employed to successfully describe photophysics in a variety of molecular materials.
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Affiliation(s)
- Tammie R Nelson
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Alexander J White
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Josiah A Bjorgaard
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Andrew E Sifain
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States.,U.S. Army Research Laboratory , Aberdeen Proving Ground , Maryland 21005 , United States
| | - Yu Zhang
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Benjamin Nebgen
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | | | - Dmitry Mozyrsky
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Adrian E Roitberg
- Department of Chemistry , University of Florida , Gainesville , Florida 32611 , United States
| | - Sergei Tretiak
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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16
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Jones AC, Kearns NM, Ho JJ, Flach JT, Zanni MT. Impact of non-equilibrium molecular packings on singlet fission in microcrystals observed using 2D white-light microscopy. Nat Chem 2019; 12:40-47. [PMID: 31792384 DOI: 10.1038/s41557-019-0368-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 10/08/2019] [Indexed: 11/09/2022]
Abstract
Singlet fission, the process of splitting a singlet exciton into two triplet excitons, has been proposed as a mechanism for improving the efficiency of future photovoltaic devices. In organic semiconductors exhibiting singlet fission, the geometric relationship between molecules plays an important role by setting the intermolecular couplings that determine the system energetics. Here, we spatially image TIPS-pentacene microcrystals using ultrafast two-dimensional white-light microscopy and discover a low-energy singlet state sparsely distributed throughout the microcrystals, with higher concentrations at edges and morphological defects. The spectra of these singlet states are consistent with slip-stacked molecular geometries and increased charge-transfer couplings. The picosecond-timescale kinetics of these low-energy singlet states matches that of the correlated triplet-pair state, which we attribute to singlet/triplet-pair interconversion at these sites. Our observations support the conclusion that small populations of geometries with favourable energetics can play outsized roles in singlet fission processes.
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Affiliation(s)
- Andrew C Jones
- Department of Chemistry, University of Wisconsin, Madison, WI, USA
| | | | - Jia-Jung Ho
- Department of Chemistry, University of Wisconsin, Madison, WI, USA
| | - Jessica T Flach
- Department of Chemistry, University of Wisconsin, Madison, WI, USA
| | - Martin T Zanni
- Department of Chemistry, University of Wisconsin, Madison, WI, USA.
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17
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Jones AC, Kearns NM, Bohlmann Kunz M, Flach JT, Zanni MT. Multidimensional Spectroscopy on the Microscale: Development of a Multimodal Imaging System Incorporating 2D White-Light Spectroscopy, Broadband Transient Absorption, and Atomic Force Microscopy. J Phys Chem A 2019; 123:10824-10836. [DOI: 10.1021/acs.jpca.9b09099] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Andrew C. Jones
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Nicholas M. Kearns
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Miriam Bohlmann Kunz
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Jessica T. Flach
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Martin T. Zanni
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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18
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Grieco C, Doucette GS, Munson KT, Swartzfager JR, Munro JM, Anthony JE, Dabo I, Asbury JB. Vibrational probe of the origin of singlet exciton fission in TIPS-pentacene solutions. J Chem Phys 2019; 151:154701. [DOI: 10.1063/1.5116586] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Christopher Grieco
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Grayson S. Doucette
- Intercollege Materials Science and Engineering Program, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Kyle T. Munson
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - John R. Swartzfager
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Jason M. Munro
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - John E. Anthony
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Ismaila Dabo
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - John B. Asbury
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
- Intercollege Materials Science and Engineering Program, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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19
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Hetzer C, Basel BS, Kopp SM, Hampel F, White FJ, Clark T, Guldi DM, Tykwinski RR. Chromophore Multiplication To Enable Exciton Delocalization and Triplet Diffusion Following Singlet Fission in Tetrameric Pentacene. Angew Chem Int Ed Engl 2019; 58:15263-15267. [PMID: 31342607 PMCID: PMC7497398 DOI: 10.1002/anie.201907221] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Indexed: 11/06/2022]
Abstract
A tetrameric pentacene, PT, has been used to explore the effects of exciton delocalization on singlet fission (SF). For the first time, triplet decorrelation through intramolecular triplet diffusion was observed following SF. Transient absorption spectroscopy was used to examine different decorrelation mechanisms (triplet diffusion versus structural changes) for PT and its dimeric equivalent PD on the basis of the rate and activation barrier of the decorrelation step. Charge-separation experiments using tetracyano-p-quinodimethane (TCNQ) to quench triplet excitons formed through SF demonstrate that enhanced intersystem crossing, that is, spin catalysis, is a widely underestimated obstacle to quantitative harvesting of the SF products. The importance of spatial separation of the decorrelated triplet states is emphasized, and independent proof that the decorrelated triplet pair state consists of two (T1 ) states per molecule is provided.
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Affiliation(s)
- Constantin Hetzer
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM)Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Nikolaus-Fiebiger-Strasse 1091058ErlangenGermany
| | - Bettina S. Basel
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM), FAUEgerlandstrasse 391058ErlangenGermany
| | - Sebastian M. Kopp
- Department of ChemistryUniversity of AlbertaEdmontonAlbertaT6G 2G2Canada
| | - Frank Hampel
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM)Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Nikolaus-Fiebiger-Strasse 1091058ErlangenGermany
| | - Fraser J. White
- Rigaku Europe, Unit B6Chaucer Business ParkWatery Lane, KemsingSevenoaksTN15 6QYUK
| | - Timothy Clark
- Computer Chemistry CenterDepartment of Chemistry and Pharmacy, FAUNägelsbachstrasse 2591052ErlangenGermany
| | - Dirk M. Guldi
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM), FAUEgerlandstrasse 391058ErlangenGermany
| | - Rik R. Tykwinski
- Department of ChemistryUniversity of AlbertaEdmontonAlbertaT6G 2G2Canada
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20
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Hetzer C, Basel BS, Kopp SM, Hampel F, White FJ, Clark T, Guldi DM, Tykwinski RR. Chromophore Multiplication To Enable Exciton Delocalization and Triplet Diffusion Following Singlet Fission in Tetrameric Pentacene. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201907221] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Constantin Hetzer
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Nikolaus-Fiebiger-Strasse 10 91058 Erlangen Germany
| | - Bettina S. Basel
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM), FAU Egerlandstrasse 3 91058 Erlangen Germany
| | - Sebastian M. Kopp
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
| | - Frank Hampel
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Nikolaus-Fiebiger-Strasse 10 91058 Erlangen Germany
| | - Fraser J. White
- Rigaku Europe, Unit B6 Chaucer Business Park Watery Lane, Kemsing Sevenoaks TN15 6QY UK
| | - Timothy Clark
- Computer Chemistry Center Department of Chemistry and Pharmacy, FAU Nägelsbachstrasse 25 91052 Erlangen Germany
| | - Dirk M. Guldi
- Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM), FAU Egerlandstrasse 3 91058 Erlangen Germany
| | - Rik R. Tykwinski
- Department of Chemistry University of Alberta Edmonton Alberta T6G 2G2 Canada
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21
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Deng GH, Wei Q, Han J, Qian Y, Luo J, Harutyunyan AR, Chen G, Bian H, Chen H, Rao Y. Vibronic fingerprint of singlet fission in hexacene. J Chem Phys 2019. [DOI: 10.1063/1.5110263] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Gang-Hua Deng
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
| | - Qianshun Wei
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China
| | - Jian Han
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
- School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Yuqin Qian
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
| | - Jun Luo
- School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | | | - Gugang Chen
- Honda Research Institute USA, Inc., San Jose, California 95134, USA
| | - Hongtao Bian
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China
| | - Hanning Chen
- Department of Chemistry, George Washington University, Washington, DC 20052, USA
| | - Yi Rao
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
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22
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Abstract
Entanglement of states is one of the most surprising and counterintuitive consequences of quantum mechanics, with potent applications in cryptography and computing. In organic semiconductor materials, one particularly significant manifestation is the spin-entangled triplet-pair state, which consists of a pair of localized triplet excitons coupled into an overall spin-0, -1, or -2 configuration. The most widely analyzed of these is the spin-0 pair, denoted 1(TT), which was initially invoked in the 1960s to explain delayed fluorescence in acene films. It is considered an essential gateway state for triplet-triplet annihilation and the reverse process, singlet fission, enabling interconversion between one singlet and two triplet excitons without any change in overall spin. This state has returned to the forefront of organic materials research in recent years, thanks both to its central role in the resurgent field of singlet fission and to its implication in a host of exotic new photophysical behaviors. Here we review the properties of triplet-pair states, from first principles to recent experimental results.
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Affiliation(s)
- Andrew J Musser
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom; ,
| | - Jenny Clark
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom; ,
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23
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Efficient triplet pair separation from intramolecular singlet fission in dibenzopentalene derivatives. Sci China Chem 2019. [DOI: 10.1007/s11426-019-9482-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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24
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Abstract
This account aims at providing an understanding of singlet fission, i.e., the photophysical process of a singlet state ( S1) splitting into two triplet states (2 × T1) in molecular chromophores. Since its discovery 50 years ago, the field of singlet fission has enjoyed rapid expansion in the past 8 years. However, there have been lingering confusion and debates on the nature of the all-important triplet pair intermediate states and the definition of singlet fission rates. Here we clarify the confusion from both theoretical and experimental perspectives. We distinguish the triplet pair state that maintains electronic coherence between the two constituent triplets, 1(TT), from one which does not, 1(T···T). Only the rate of formation of 1(T···T) is defined as that of singlet fission. We present distinct experimental evidence for 1(TT), whose formation may occur via incoherent and/or vibronic coherent mechanisms. We discuss the challenges in treating singlet fission beyond the dimer approximation, in understanding the often neglected roles of delocalization on singlet fission rates, and in realizing the much lauded goal of increasing solar energy conversion efficiencies with singlet fission chromophores.
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Affiliation(s)
- Kiyoshi Miyata
- Department of Chemistry , Columbia University , New York , New York 10027 , United States.,Department of Chemistry , Kyushu University , Fukuoka 819-0395 , Japan
| | - Felisa S Conrad-Burton
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - Florian L Geyer
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - X-Y Zhu
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
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25
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Krishnapriya KC, Roy P, Puttaraju B, Salzner U, Musser AJ, Jain M, Dasgupta J, Patil S. Spin density encodes intramolecular singlet exciton fission in pentacene dimers. Nat Commun 2019; 10:33. [PMID: 30604740 PMCID: PMC6318326 DOI: 10.1038/s41467-018-07736-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 11/25/2018] [Indexed: 11/09/2022] Open
Abstract
The formation of two triplet excitons at the cost of one photon via singlet exciton fission in organic semiconductors can potentially enhance the photocurrent in photovoltaic devices. However, the role of spin density distribution in driving this photophysical process has been unclear until now. Here we present the significance of electronic spin density distribution in facilitating efficient intramolecular singlet exciton fission (iSEF) in π-bridged pentacene dimers. We synthetically modulate the spin density distribution in a series of pentacene dimers using phenyl-, thienyl- and selenyl- flanked diketopyrrolopyrrole (DPP) derivatives as π-bridges. Using femtosecond transient absorption spectroscopy, we find that efficient iSEF is only observed for the phenyl-derivative in ~2.4 ps while absent in the other two dimers. Electronic structure calculations reveal that phenyl-DPP bridge localizes α- and β-spin densities on distinct terminal pentacenes. Upon photoexcitation, a spin exchange mechanism enables iSEF from a singlet state which has an innate triplet pair character.
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Affiliation(s)
- K C Krishnapriya
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Palas Roy
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, 400005, India.,Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Boregowda Puttaraju
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Ulrike Salzner
- Department of Chemistry, Bilkent University, Ankara, 06800, Turkey
| | - Andrew J Musser
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S37RH, UK
| | - Manish Jain
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India
| | - Jyotishman Dasgupta
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, 400005, India.
| | - Satish Patil
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012, India.
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26
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Jana S, Yapamanu AL, Umapathy S. Unraveling structural dynamics in isoenergetic excited S1 and multi-excitonic 1(TT) states of 9,10-bis(phenylethynyl)anthracene (BPEA) in solution via ultrafast Raman loss spectroscopy. Phys Chem Chem Phys 2019; 21:14341-14349. [DOI: 10.1039/c8cp06658b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ultrafast Raman loss spectroscopy provides a direct evidence for the structural changes that occur during the evolution from the S1 to the 1(TT) state of BPEA in solution.
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Affiliation(s)
- Sanjib Jana
- Department of Instrumentation and Applied Physics
- Bangalore 560012
- India
| | | | - Siva Umapathy
- Department of Instrumentation and Applied Physics
- Bangalore 560012
- India
- Department of Inorganic and Physical Chemistry and Applied Physics
- Bangalore 560012
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27
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Abstract
The highly unusual state, 1(TT), is a coupled, double triplet state that has recently garnered significant attention. This multiexcitonic state can be formed by a quantum transition from a single-photon bright state in a variety of organic semiconducting materials. 1(TT)'s transient nature and similarity to independent triplets, however, has led to significant difficulties in characterization and prediction of its properties. Recent progress describing 1(TT) from theory and experiment are breaking through these difficulties, and have greatly advanced our comprehension of this state. Starting from the early description of 1(TT) in polyenes, this perspective discusses formation mechanisms, spectroscopic signatures, and the scope of intertriplet interactions. When employing singlet fission to generate charge carriers in a solar cell, 1(TT) has a central role. Due to the variety of coupling strengths between triplet states in 1(TT) amongst different chromophores, two different strategies are discussed to enable efficient charge carrier extraction. Continued growth in our understanding of 1(TT) may lead to control over complex quantum states for intriguing applications beyond high-efficiency, organic solar cells.
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Affiliation(s)
- Hyungjun Kim
- Department of Chemistry, Incheon National University, Incheon 22012, Republic of Korea.
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28
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Pensack RD, Tilley AJ, Grieco C, Purdum GE, Ostroumov EE, Granger DB, Oblinsky DG, Dean JC, Doucette GS, Asbury JB, Loo YL, Seferos DS, Anthony JE, Scholes GD. Striking the right balance of intermolecular coupling for high-efficiency singlet fission. Chem Sci 2018; 9:6240-6259. [PMID: 30090312 PMCID: PMC6062843 DOI: 10.1039/c8sc00293b] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 05/31/2018] [Indexed: 12/02/2022] Open
Abstract
Singlet fission is a process that splits collective excitations, or excitons, into two with unity efficiency. This exciton splitting process, unique to molecular photophysics, has the potential to considerably improve the efficiency of optoelectronic devices through more efficient light harvesting. While the first step of singlet fission has been characterized in great detail, subsequent steps critical to achieving overall highly-efficient singlet-to-triplet conversion are only just beginning to become well understood. One of the most elementary suggestions, which has yet to be tested, is that an appropriately balanced coupling is necessary to ensure overall highly efficient singlet fission; that is, the coupling needs to be strong enough so that the first step is fast and efficient, yet weak enough to ensure the independent behavior of the resultant triplets. In this work, we show how high overall singlet-to-triplet conversion efficiencies can be achieved in singlet fission by ensuring that the triplets comprising the triplet pair behave as independently as possible. We show that side chain sterics govern local packing in amorphous pentacene derivative nanoparticles, and that this in turn controls both the rate at which triplet pairs form and the rate at which they decay. We show how compact side chains and stronger couplings promote a triplet pair that effectively couples to the ground state, whereas bulkier side chains promote a triplet pair that appears more like two independent and long-lived triplet excitations. Our results show that the triplet pair is not emissive, that its decay is best viewed as internal conversion rather than triplet-triplet annihilation, and perhaps most critically that, in contrast to a number of recent suggestions, the triplets comprising the initially formed triplet pair cannot be considered independently. This work represents a significant step toward better understanding intermediates in singlet fission, and how molecular packing and couplings govern overall triplet yields.
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Affiliation(s)
- Ryan D Pensack
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
| | - Andrew J Tilley
- Department of Chemistry , University of Toronto , Toronto , Ontario M5S 3H6 , Canada
| | - Christopher Grieco
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , USA
| | - Geoffrey E Purdum
- Department of Chemical and Biological Engineering , Princeton University , Princeton , New Jersey 08544 , USA
| | - Evgeny E Ostroumov
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
| | - Devin B Granger
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40506 , USA .
| | - Daniel G Oblinsky
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
| | - Jacob C Dean
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
| | - Grayson S Doucette
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , USA
| | - John B Asbury
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , USA
| | - Yueh-Lin Loo
- Department of Chemical and Biological Engineering , Princeton University , Princeton , New Jersey 08544 , USA
- Andlinger Center for Energy and the Environment , Princeton University , Princeton , New Jersey 08544 , USA
| | - Dwight S Seferos
- Department of Chemistry , University of Toronto , Toronto , Ontario M5S 3H6 , Canada
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , Toronto , Ontario M5S 3E5 , Canada
| | - John E Anthony
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40506 , USA .
| | - Gregory D Scholes
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
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29
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Chen M, Bae YJ, Mauck CM, Mandal A, Young RM, Wasielewski MR. Singlet Fission in Covalent Terrylenediimide Dimers: Probing the Nature of the Multiexciton State Using Femtosecond Mid-Infrared Spectroscopy. J Am Chem Soc 2018; 140:9184-9192. [PMID: 29949371 DOI: 10.1021/jacs.8b04830] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Singlet fission (SF) is a spin-allowed process that involves absorption of a photon by two electronically interacting chromophores to produce a singlet exciton state, 1(S1S0), followed by rapid formation of two triplet excitons if the singlet exciton energy is about twice that of the triplet exciton. The initial formation of the multiexciton correlated triplet pair state, 1(T1T1), is thought to involve the agency of charge transfer (CT) states. The dynamics of these electronic states were studied in a covalent slip-stacked terrylene-3,4:11,12-bis(dicarboximide) (TDI) dimer in which the conformation of two TDI molecules is determined by a xanthene spacer (XanTDI2). Femtosecond mid-infrared (fsIR) spectroscopy shows that the multiexciton 1(T1T1) state has absorptions characteristic of the T1 state in the carbonyl stretch region of the IR spectrum, in addition to IR absorptions specific to the CT state in the C═C stretch region. The simultaneous presence of CT and triplet state features in both high dielectric constant CH2Cl2 and low dielectric constant 1,4-dioxane throughout the multiexciton state lifetime suggests that this state has both CT and triplet character.
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Affiliation(s)
- Michelle Chen
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208-3113 , United States
| | - Youn Jue Bae
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208-3113 , United States
| | - Catherine M Mauck
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208-3113 , United States
| | - Aritra Mandal
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208-3113 , United States
| | - Ryan M Young
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208-3113 , United States
| | - Michael R Wasielewski
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern , Northwestern University , Evanston , Illinois 60208-3113 , United States
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30
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Kennehan ER, Doucette GS, Marshall AR, Grieco C, Munson KT, Beard MC, Asbury JB. Electron-Phonon Coupling and Resonant Relaxation from 1D and 1P States in PbS Quantum Dots. ACS NANO 2018; 12:6263-6272. [PMID: 29792675 DOI: 10.1021/acsnano.8b03216] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Observations of the hot-phonon bottleneck, which is predicted to slow the rate of hot carrier cooling in quantum confined nanocrystals, have been limited to date for reasons that are not fully understood. We used time-resolved infrared spectroscopy to directly measure higher energy intraband transitions in PbS colloidal quantum dots. Direct measurements of these intraband transitions permitted detailed analysis of the electronic overlap of the quantum confined states that may influence their relaxation processes. In smaller PbS nanocrystals, where the hot-phonon bottleneck is expected to be most pronounced, we found that relaxation of parity selection rules combined with stronger electron-phonon coupling led to greater spectral overlap of transitions among the quantum confined states. This created pathways for fast energy transfer and relaxation that may bypass the predicted hot-phonon bottleneck. In contrast, larger, but still quantum confined nanocrystals did not exhibit such relaxation of the parity selection rules and possessed narrower intraband states. These observations were consistent with slower relaxation dynamics that have been measured in larger quantum confined systems. These findings indicated that, at small radii, electron-phonon interactions overcome the advantageous increase in energetic separation of the electronic states for PbS quantum dots. Selection of appropriately sized quantum dots, which minimize spectral broadening due to electron-phonon interactions while maximizing electronic state separation, is necessary to observe the hot-phonon bottleneck. Such optimization may provide a framework for achieving efficient hot carrier collection and multiple exciton generation.
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Affiliation(s)
| | | | - Ashley R Marshall
- Chemical and Materials Science , National Renewable Energy Laboratory (NREL) , Golden , Colorado 80401 , United States
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , United States
| | | | | | - Matthew C Beard
- Chemical and Materials Science , National Renewable Energy Laboratory (NREL) , Golden , Colorado 80401 , United States
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , United States
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Kim H, Keller B, Ho-Wu R, Abeyasinghe N, Vázquez RJ, Goodson T, Zimmerman PM. Enacting Two-Electron Transfer from a Double-Triplet State of Intramolecular Singlet Fission. J Am Chem Soc 2018; 140:7760-7763. [DOI: 10.1021/jacs.8b01884] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hyungjun Kim
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Bradley Keller
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Rosina Ho-Wu
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Neranga Abeyasinghe
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Ricardo J. Vázquez
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Theodore Goodson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Paul M. Zimmerman
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Basel BS, Zirzlmeier J, Hetzer C, Reddy SR, Phelan BT, Krzyaniak MD, Volland MK, Coto PB, Young RM, Clark T, Thoss M, Tykwinski RR, Wasielewski MR, Guldi DM. Evidence for Charge-Transfer Mediation in the Primary Events of Singlet Fission in a Weakly Coupled Pentacene Dimer. Chem 2018. [DOI: 10.1016/j.chempr.2018.04.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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