201
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Zhu T, Wan Y, Huang L. Direct Imaging of Frenkel Exciton Transport by Ultrafast Microscopy. Acc Chem Res 2017; 50:1725-1733. [PMID: 28678469 DOI: 10.1021/acs.accounts.7b00155] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Long-range transport of Frenkel excitons is crucial for achieving efficient molecular-based solar energy harvesting. Understanding of exciton transport mechanisms is important for designing materials for solar energy applications. One major bottleneck in unraveling of exciton transport mechanisms is the lack of direct measurements to provide information in both spatial and temporal domains, imposed by the combination of fast energy transfer (typically ≤1 ps) and short exciton diffusion lengths (typically ≤100 nm). This challenge requires developing experimental tools to directly characterize excitation energy transport, and thus facilitate the elucidation of mechanisms. To address this challenge, we have employed ultrafast transient absorption microscopy (TAM) as a means to directly image exciton transport with ∼200 fs time resolution and ∼50 nm spatial precision. By mapping population in spatial and temporal domains, such approach has unraveled otherwise obscured information and provided important parameters for testing exciton transport models. In this Account, we discuss the recent progress in imaging Frenkel exciton migration in molecular crystals and aggregates by ultrafast microscopy. First, we establish the validity of the TAM methods by imaging singlet and triplet exciton transport in a series of polyacene single crystals that undergo singlet fission. A new singlet-mediated triplet transport pathway has been revealed by TAM, resulting from the equilibrium between triplet and singlet exciton populations. Such enhancement of triplet exciton transport enables triplet excitons to migrate as singlet excitons and leads to orders of magnitude faster apparent triplet exciton diffusion rate in the picosecond and nanosecond time scales, favorable for solar cell applications. Next we discuss how information obtained by ultrafast microscopy can evaluate coherent effects in exciton transport. We use tubular molecular aggregates that could support large exciton delocalization sizes as a model system. The initial experiments measure exciton diffusion constants of 3-6 cm2 s-1, 3-5 times higher than the incoherent limit predicted by theory, suggesting that coherent effects play a role. In summary, combining ultrafast spectroscopic methods with microscopic techniques provides a direct approach for obtaining important parameters to unravel the underlying exciton transport mechanisms in molecular solids. We discuss future directions to bridge the gap in understanding of fundamental energy transfer theories to include coherent and incoherent effects. We are still in the infancy of ultrafast microscopy, and the vast potential is not limited to the systems discussed in this Account.
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Affiliation(s)
- Tong Zhu
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Yan Wan
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Libai Huang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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202
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Yong CK, Musser AJ, Bayliss SL, Lukman S, Tamura H, Bubnova O, Hallani RK, Meneau A, Resel R, Maruyama M, Hotta S, Herz LM, Beljonne D, Anthony JE, Clark J, Sirringhaus H. The entangled triplet pair state in acene and heteroacene materials. Nat Commun 2017; 8:15953. [PMID: 28699637 PMCID: PMC5510179 DOI: 10.1038/ncomms15953] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 05/17/2017] [Indexed: 12/18/2022] Open
Abstract
Entanglement of states is one of the most surprising and counter-intuitive consequences of quantum mechanics, with potent applications in cryptography and computing. In organic materials, one particularly significant manifestation is the spin-entangled triplet-pair state, which mediates the spin-conserving fission of one spin-0 singlet exciton into two spin-1 triplet excitons. Despite long theoretical and experimental exploration, the nature of the triplet-pair state and inter-triplet interactions have proved elusive. Here we use a range of organic semiconductors that undergo singlet exciton fission to reveal the photophysical properties of entangled triplet-pair states. We find that the triplet pair is bound with respect to free triplets with an energy that is largely material independent (∼30 meV). During its lifetime, the component triplets behave cooperatively as a singlet and emit light through a Herzberg-Teller-type mechanism, resulting in vibronically structured photoluminescence. In photovoltaic blends, charge transfer can occur from the bound triplet pairs with >100% photon-to-charge conversion efficiency.
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Affiliation(s)
- Chaw Keong Yong
- Cavendish Laboratory, Optoelectronics Group, University of Cambridge, Madingley Road, J.J. Thomson Avenue, Cambridge CB3 0HE, UK.,Department of Physics, University of California, Berkeley, California 94720, USA
| | - Andrew J Musser
- Cavendish Laboratory, Optoelectronics Group, University of Cambridge, Madingley Road, J.J. Thomson Avenue, Cambridge CB3 0HE, UK.,Department of Physics and Astronomy, The University of Sheffield, Hicks Buildling, Hounsfield Road, Sheffield S3 7RH, UK
| | - Sam L Bayliss
- Cavendish Laboratory, Optoelectronics Group, University of Cambridge, Madingley Road, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Steven Lukman
- Cavendish Laboratory, Optoelectronics Group, University of Cambridge, Madingley Road, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Hiroyuki Tamura
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Olga Bubnova
- Cavendish Laboratory, Optoelectronics Group, University of Cambridge, Madingley Road, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Rawad K Hallani
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA
| | - Aurélie Meneau
- Cavendish Laboratory, Optoelectronics Group, University of Cambridge, Madingley Road, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Roland Resel
- Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Munetaka Maruyama
- Faculty of Materials Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Shu Hotta
- Faculty of Materials Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Laura M Herz
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, B-7000 Mons, Belgium
| | - John E Anthony
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA
| | - Jenny Clark
- Department of Physics and Astronomy, The University of Sheffield, Hicks Buildling, Hounsfield Road, Sheffield S3 7RH, UK
| | - Henning Sirringhaus
- Cavendish Laboratory, Optoelectronics Group, University of Cambridge, Madingley Road, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
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203
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Trinh MT, Pinkard A, Pun AB, Sanders SN, Kumarasamy E, Sfeir MY, Campos LM, Roy X, Zhu XY. Distinct properties of the triplet pair state from singlet fission. SCIENCE ADVANCES 2017; 3:e1700241. [PMID: 28740866 PMCID: PMC5510972 DOI: 10.1126/sciadv.1700241] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 05/25/2017] [Indexed: 05/12/2023]
Abstract
Singlet fission, the conversion of a singlet exciton (S1) to two triplets (2 × T1), may increase the solar energy conversion efficiency beyond the Shockley-Queisser limit. This process is believed to involve the correlated triplet pair state 1(TT). Despite extensive research, the nature of the 1(TT) state and its spectroscopic signature remain actively debated. We use an end-connected pentacene dimer (BP0) as a model system and show evidence for a tightly bound 1(TT) state. It is characterized in the near-infrared (IR) region (~1.0 eV) by a distinct excited-state absorption (ESA) spectral feature, which closely resembles that of the S1 state; both show vibronic progressions of the aromatic ring breathing mode. We assign these near-IR spectra to 1(TT)→Sn and S1→Sn' transitions; Sn and Sn' likely come from the antisymmetric and symmetric linear combinations, respectively, of the S2 state localized on each pentacene unit in the dimer molecule. The 1(TT)→Sn transition is an indicator of the intertriplet electronic coupling strength, because inserting a phenylene spacer or twisting the dihedral angle between the two pentacene chromophores decreases the intertriplet electronic coupling and diminishes this ESA peak. In addition to spectroscopic signature, the tightly bound 1(TT) state also shows chemical reactivity that is distinctively different from that of an individual T1 state. Using an electron-accepting iron oxide molecular cluster [Fe8O4] linked to the pentacene or pentacene dimer (BP0), we show that electron transfer to the cluster occurs efficiently from an individual T1 in pentacene but not from the tightly bound 1(TT) state. Thus, reducing intertriplet electronic coupling in 1(TT) via molecular design might be necessary for the efficient harvesting of triplets from intramolecular singlet fission.
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Affiliation(s)
- M. Tuan Trinh
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Andrew Pinkard
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Andrew B. Pun
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Samuel N. Sanders
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Elango Kumarasamy
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Matthew Y. Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Luis M. Campos
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Xavier Roy
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - X.-Y. Zhu
- Department of Chemistry, Columbia University, New York, NY 10027, USA
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204
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Sardar S. Monitoring of the energy levels by heteroatom substitution to hexacene and controlling over singlet fission and photo-oxidative resistance. J Mol Graph Model 2017; 74:24-37. [DOI: 10.1016/j.jmgm.2017.01.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/26/2017] [Accepted: 01/27/2017] [Indexed: 10/20/2022]
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205
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Castellanos MA, Huo P. Enhancing Singlet Fission Dynamics by Suppressing Destructive Interference between Charge-Transfer Pathways. J Phys Chem Lett 2017; 8:2480-2488. [PMID: 28520444 DOI: 10.1021/acs.jpclett.7b00972] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We apply a real-time path-integral approach to investigate the charge-transfer (CT)-mediated singlet fission quantum dynamics in a model pentacene dimer. Our path-integral method gives reliable fission dynamics across various reaction regimes as well as a broad range of reorganization energies and temperatures. With this method, we investigated the destructive interference between the two CT-mediated fission pathways and discovered two mechanisms that can suppress this deleterious effect. First, increasing the energy gap between the two CT states effectively shuts down the high-lying CT pathway, leaving a better functioning low-lying CT pathway with a minimum amount of destructive interference. Second, intermolecular vibrations induce electronic coupling fluctuations, such that the destructive cancellations due to the different signs in static electronic couplings are suppressed. Our numerical results suggest that these two effects can enhance the fission rate up to three times. These findings reveal promising design principles for more efficient singlet fission materials.
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Affiliation(s)
- Maria A Castellanos
- Department of Chemistry, University of Rochester , 120 Trustee Road, Rochester, New York 14627, United States
- Department of Chemistry, Universidad Icesi , Cali, Colombia
| | - Pengfei Huo
- Department of Chemistry, University of Rochester , 120 Trustee Road, Rochester, New York 14627, United States
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206
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Miyata K, Kurashige Y, Watanabe K, Sugimoto T, Takahashi S, Tanaka S, Takeya J, Yanai T, Matsumoto Y. Coherent singlet fission activated by symmetry breaking. Nat Chem 2017; 9:983-989. [PMID: 28937675 DOI: 10.1038/nchem.2784] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 04/21/2017] [Indexed: 12/20/2022]
Abstract
Singlet fission, in which a singlet exciton is converted to two triplet excitons, is a process that could be beneficial in photovoltaic applications. A full understanding of the dynamics of singlet fission in molecular systems requires detailed knowledge of the relevant potential energy surfaces and their (conical) intersections. However, obtaining such information is a nontrivial task, particularly for molecular aggregates. Here we investigate singlet fission in rubrene crystals using transient absorption spectroscopy and state-of-the-art quantum chemical calculations. We observe a coherent and ultrafast singlet-fission channel as well as the well-known and conventional thermally assisted incoherent channel. This coherent channel is accessible because the conical intersection for singlet fission on the excited-state potential energy surface is located very close to the equilibrium position of the ground-state potential energy surface and also because of the excitation of an intermolecular symmetry-breaking mode, which activates the electronic coupling necessary for singlet fission.
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Affiliation(s)
- Kiyoshi Miyata
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yuki Kurashige
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.,Institute for Molecular Science, Okazaki 444-8585, Japan.,PRESTO, Japan Science and Technology Agency (JST), Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan
| | - Kazuya Watanabe
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Toshiki Sugimoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.,PRESTO, Japan Science and Technology Agency (JST), Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan
| | - Shota Takahashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Shunsuke Tanaka
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Jun Takeya
- Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8561, Japan
| | - Takeshi Yanai
- Institute for Molecular Science, Okazaki 444-8585, Japan
| | - Yoshiyasu Matsumoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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207
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Surakhot Y, Laszlo V, Chitpakdee C, Promarak V, Sudyoadsuk T, Kungwan N, Kowalczyk T, Irle S, Jungsuttiwong S. Theoretical rationalization for reduced charge recombination in bulky carbazole-based sensitizers in solar cells. J Comput Chem 2017; 38:901-909. [PMID: 28192642 DOI: 10.1002/jcc.24751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/12/2016] [Accepted: 12/31/2016] [Indexed: 11/09/2022]
Abstract
The search for greater efficiency in organic dye-sensitized solar cells (DSCs) and in their perovskite cousins is greatly aided by a more complete understanding of the spectral and morphological properties of the photoactive layer. This investigation resolves a discrepancy in the observed photoconversion efficiency (PCE) of two closely related DSCs based on carbazole-containing D-π-A organic sensitizers. Detailed theoretical characterization of the absorption spectra, dye adsorption on TiO2 , and electronic couplings for charge separation and recombination permit a systematic determination of the origin of the difference in PCE. Although the two dyes produce similar spectral features, ground- and excited-state density functional theory (DFT) simulations reveal that the dye with the bulkier donor group adsorbs more strongly to TiO2 , experiences limited π-π aggregation, and is more resistant to loss of excitation energy via charge recombination on the dye. The effects of conformational flexibility on absorption spectra and on the electronic coupling between the bright exciton and charge-transfer states are revealed to be substantial and are characterized through density-functional tight-binding (DFTB) molecular dynamics sampling. These simulations offer a mechanistic explanation for the superior open-circuit voltage and short-circuit current of the bulky-donor dye sensitizer and provide theoretical justification of an important design feature for the pursuit of greater photocurrent efficiency in DSCs. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Yaowarat Surakhot
- Center for Organic Electronic and Alternative Energy, Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani, 34190, Thailand
| | - Viktor Laszlo
- Department of Chemistry, Advanced Materials Science and Engineering Center, and Institute for Energy Studies, Western Washington University, Bellingham, Washington, 98225
| | - Chirawat Chitpakdee
- National Nanotechnology Center, National Science and Technology Development Agency, Klong Luang, Pathumthani, 12120, Thailand
| | - Vinich Promarak
- School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong, 21210, Thailand
| | - Taweesak Sudyoadsuk
- School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan, Rayong, 21210, Thailand
| | - Nawee Kungwan
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Tim Kowalczyk
- Department of Chemistry, Advanced Materials Science and Engineering Center, and Institute for Energy Studies, Western Washington University, Bellingham, Washington, 98225
| | - Stephan Irle
- Department of Chemistry, Graduate School of Science, Nagoya University, Institute of Transformational Biomolecules (WPI-ITbM) and, Nagoya, 464-8602, Japan
| | - Siriporn Jungsuttiwong
- Center for Organic Electronic and Alternative Energy, Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani, 34190, Thailand
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208
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Xia J, Sanders SN, Cheng W, Low JZ, Liu J, Campos LM, Sun T. Singlet Fission: Progress and Prospects in Solar Cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29. [PMID: 27973702 DOI: 10.1002/adma.201601652] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 08/07/2016] [Indexed: 05/12/2023]
Abstract
The third generation of photovoltaic technology aims to reduce the fabrication cost and improve the power conversion efficiency (PCE) of solar cells. Singlet fission (SF), an efficient multiple exciton generation (MEG) process in organic semiconductors, is one promising way to surpass the Shockley-Queisser limit of conventional single-junction solar cells. Traditionally, this MEG process has been observed as an intermolecular process in organic materials. The implementation of intermolecular SF in photovoltaic devices has achieved an external quantum efficiency of over 100% and demonstrated significant promise for boosting the PCE of third generation solar cells. More recently, efficient intramolecular SF has been reported. Intramolecular SF materials are modular and have the potential to overcome certain design constraints that intermolecular SF materials possess, which may allow for more facile integration into devices.
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Affiliation(s)
- Jianlong Xia
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
| | - Samuel N Sanders
- Department of Chemistry, Columbia University, New York, New York, 10027, United States
| | - Wei Cheng
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
| | - Jonathan Z Low
- Department of Chemistry, Columbia University, New York, New York, 10027, United States
| | - Jinping Liu
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
| | - Luis M Campos
- Department of Chemistry, Columbia University, New York, New York, 10027, United States
| | - Taolei Sun
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
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209
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Carey TJ, Snyder JL, Miller EG, Sammakia T, Damrauer NH. Synthesis of Geometrically Well-Defined Covalent Acene Dimers for Mechanistic Exploration of Singlet Fission. J Org Chem 2017; 82:4866-4874. [DOI: 10.1021/acs.joc.7b00602] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Thomas J. Carey
- Department of Chemistry and
Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Jamie L. Snyder
- Department of Chemistry and
Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Ethan G. Miller
- Department of Chemistry and
Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Tarek Sammakia
- Department of Chemistry and
Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Niels H. Damrauer
- Department of Chemistry and
Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
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210
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Uchida K, Kubo T, Yamanaka D, Furube A, Matsuzaki H, Nishii R, Sakagami Y, Abulikemu A, Kamada K. Synthesis, crystal structure, and photophysical properties of 2,9-disubstituted peropyrene derivatives. CAN J CHEM 2017. [DOI: 10.1139/cjc-2016-0569] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Peropyrene is a promising candidate molecule for use in organic solar cells based on singlet fission, because it fulfills the energy matching requirement for singlet fission. We prepare three 2,9-disubstitued peropyrene derivatives and investigate their crystal structures, photophysical properties, and singlet fission phenomenon. Although each derivative shows different molecular overlap motifs in solid state, no singlet fission occurs under normal exciton density conditions due to the substantial stabilization of the first excited singlet (S1) state. In contrast, under high exciton density conditions, singlet fission from highly excited singlet (Sn) states, which is generated by singlet–singlet exciton annihilation, takes place to produce a triplet exciton. We also investigate the reverse process of singlet fission, that is, triplet–triplet annihilation, of peropyrene in solution state to explore the possibility of photon upconversion.
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Affiliation(s)
- Kazuyuki Uchida
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takashi Kubo
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Daiki Yamanaka
- Department of Optical Science, Tokushima University, 2-1 Minamijosanjima, Tokushima, 770-8506, Japan
| | - Akihiro Furube
- Department of Optical Science, Tokushima University, 2-1 Minamijosanjima, Tokushima, 770-8506, Japan
| | - Hiroyuki Matsuzaki
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Ritsuki Nishii
- IFMRI, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
| | - Yusuke Sakagami
- IFMRI, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
| | - Aizitiaili Abulikemu
- IFMRI, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan
| | - Kenji Kamada
- IFMRI, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
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211
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Wang T, Kafle TR, Kattel B, Chan WL. A Multidimensional View of Charge Transfer Excitons at Organic Donor–Acceptor Interfaces. J Am Chem Soc 2017; 139:4098-4106. [DOI: 10.1021/jacs.6b13312] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ti Wang
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Tika R. Kafle
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Bhupal Kattel
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
| | - Wai-Lun Chan
- Department of Physics and
Astronomy, University of Kansas, Lawrence, Kansas 66045, United States
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212
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Mukhopadhyay T, Musser AJ, Puttaraju B, Dhar J, Friend RH, Patil S. Is the Chemical Strategy for Imbuing "Polyene" Character in Diketopyrrolopyrrole-Based Chromophores Sufficient for Singlet Fission? J Phys Chem Lett 2017; 8:984-991. [PMID: 28112521 DOI: 10.1021/acs.jpclett.6b02919] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, we have rationally designed and synthesized a novel thiophene-diketopyrrolopyrrole (TDPP)-vinyl-based dimer. We have investigated the optical and electronic properties and have probed the photophysical dynamics using transient absorption to investigate the possibility of singlet exciton fission. These revealed extremely rapid decay to the ground state (<50 ps), which we confirm is due to intramolecular excitonic processes rather than large-scale conformational change enabled by the vinyl linker. In all cases, the main excited state appears to be "dark", suggesting rapid internal conversion into a dark 2Ag-type singlet state. We found no evidence of triplet formation in TDPP-V-TDPP under direct photoexcitation. This may be a consequence of significant singlet stabilization in the dimer, bringing it below the energy needed to form two triplets. Our studies on this model compound set valuable lessons for design of novel triplet-forming materials and highlight the need for more broadly applicable design principles.
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Affiliation(s)
- Tushita Mukhopadhyay
- Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India
| | - Andrew J Musser
- Department of Physics and Astronomy, University of Sheffield , Sheffield, United Kingdom
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Boregowda Puttaraju
- Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India
| | - Joydeep Dhar
- Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India
| | - Richard H Friend
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Satish Patil
- Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India
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213
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Fujihashi Y, Chen L, Ishizaki A, Wang J, Zhao Y. Effect of high-frequency modes on singlet fission dynamics. J Chem Phys 2017; 146:044101. [DOI: 10.1063/1.4973981] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yuta Fujihashi
- Division of Materials Science, Nanyang Technological University, Singapore 639798, Singapore
| | - Lipeng Chen
- Division of Materials Science, Nanyang Technological University, Singapore 639798, Singapore
| | - Akihito Ishizaki
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan
- School of Physical Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Junling Wang
- Division of Materials Science, Nanyang Technological University, Singapore 639798, Singapore
| | - Yang Zhao
- Division of Materials Science, Nanyang Technological University, Singapore 639798, Singapore
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214
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Gibson J, Penfold TJ. Nonadiabatic coupling reduces the activation energy in thermally activated delayed fluorescence. Phys Chem Chem Phys 2017; 19:8428-8434. [DOI: 10.1039/c7cp00719a] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The activation energy of thermally activated delayed fluorescence can be reduced by nonadiabatic coupling.
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Affiliation(s)
- J. Gibson
- School of Chemistry
- Newcastle University
- Newcastle upon Tyne
- UK
| | - T. J. Penfold
- School of Chemistry
- Newcastle University
- Newcastle upon Tyne
- UK
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215
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López-Carballeira D, Casanova D, Ruipérez F. Theoretical design of conjugated diradicaloids as singlet fission sensitizers: quinones and methylene derivatives. Phys Chem Chem Phys 2017; 19:30227-30238. [DOI: 10.1039/c7cp05120d] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
New conjugated diradicaloids as potential candidates for singlet fission sensitizers.
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Affiliation(s)
- Diego López-Carballeira
- POLYMAT, University of the Basque Country UPV/EHU
- Joxe Mari Korta Center
- Donostia-San Sebastián
- Spain
| | - David Casanova
- Donostia International Physics Center (DIPC) and Kimika Fakultatea
- Euskal Herriko Unibertsitatea (UPV/EHU)
- 20080 Donostia
- Spain
- IKERBASQUE
| | - Fernando Ruipérez
- POLYMAT, University of the Basque Country UPV/EHU
- Joxe Mari Korta Center
- Donostia-San Sebastián
- Spain
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216
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Ito S, Nagami T, Nakano M. Rational design of doubly-bridged chromophores for singlet fission and triplet–triplet annihilation. RSC Adv 2017. [DOI: 10.1039/c7ra06032g] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A novel multiple-bridging realizes rational molecular design for efficient singlet fission and triplet–triplet annihilation.
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Affiliation(s)
- S. Ito
- Department of Materials Engineering Science
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
| | - T. Nagami
- Department of Materials Engineering Science
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
| | - M. Nakano
- Department of Materials Engineering Science
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
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217
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Benchmarking singlet and triplet excitation energies of molecular semiconductors for singlet fission: Tuning the amount of HF exchange and adjusting local correlation to obtain accurate functionals for singlet–triplet gaps. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2016.08.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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218
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Singlet Fission: Optimization of Chromophore Dimer Geometry. ADVANCES IN QUANTUM CHEMISTRY 2017. [DOI: 10.1016/bs.aiq.2017.03.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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219
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Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering. Nat Commun 2016; 7:13622. [PMID: 27924819 PMCID: PMC5150654 DOI: 10.1038/ncomms13622] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 10/17/2016] [Indexed: 12/23/2022] Open
Abstract
Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics.
The understanding of how a singlet exciton separates into triplet states in organic semiconductors is crucial to the design of efficient organic solar cells. Here, Lukman et al. identify the role played by charge-transfer states during triplet formation through side-group engineering of pentacenes.
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220
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Dynamics of the triplet-pair state reveals the likely coexistence of coherent and incoherent singlet fission in crystalline hexacene. Nat Chem 2016; 9:341-346. [DOI: 10.1038/nchem.2665] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 10/03/2016] [Indexed: 12/19/2022]
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221
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Grieco C, Doucette GS, Pensack RD, Payne MM, Rimshaw A, Scholes GD, Anthony JE, Asbury JB. Dynamic Exchange During Triplet Transport in Nanocrystalline TIPS-Pentacene Films. J Am Chem Soc 2016; 138:16069-16080. [DOI: 10.1021/jacs.6b10010] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher Grieco
- 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
| | - Ryan D. Pensack
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Marcia M. Payne
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Adam Rimshaw
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Gregory D. Scholes
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - John E. Anthony
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - John B. Asbury
- 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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222
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Schnedermann C, Lim JM, Wende T, Duarte AS, Ni L, Gu Q, Sadhanala A, Rao A, Kukura P. Sub-10 fs Time-Resolved Vibronic Optical Microscopy. J Phys Chem Lett 2016; 7:4854-4859. [PMID: 27934055 PMCID: PMC5684689 DOI: 10.1021/acs.jpclett.6b02387] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 11/10/2016] [Indexed: 05/22/2023]
Abstract
We introduce femtosecond wide-field transient absorption microscopy combining sub-10 fs pump and probe pulses covering the complete visible (500-650 nm) and near-infrared (650-950 nm) spectrum with diffraction-limited optical resolution. We demonstrate the capabilities of our system by reporting the spatially- and spectrally-resolved transient electronic response of MAPbI3-xClx perovskite films and reveal significant quenching of the transient bleach signal at grain boundaries. The unprecedented temporal resolution enables us to directly observe the formation of band-gap renormalization, completed in 25 fs after photoexcitation. In addition, we acquire hyperspectral Raman maps of TIPS pentacene films with sub-400 nm spatial and sub-15 cm-1 spectral resolution covering the 100-2000 cm-1 window. Our approach opens up the possibility of studying ultrafast dynamics on nanometer length and femtosecond time scales in a variety of two-dimensional and nanoscopic systems.
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Affiliation(s)
- Christoph Schnedermann
- Physical
and Theoretical Chemistry Laboratory, University
of Oxford, South Parks
Road, Oxford OX1 3QZ, United Kingdom
| | - Jong Min Lim
- Physical
and Theoretical Chemistry Laboratory, University
of Oxford, South Parks
Road, Oxford OX1 3QZ, United Kingdom
| | - Torsten Wende
- Physical
and Theoretical Chemistry Laboratory, University
of Oxford, South Parks
Road, Oxford OX1 3QZ, United Kingdom
| | - Alex S. Duarte
- Physical
and Theoretical Chemistry Laboratory, University
of Oxford, South Parks
Road, Oxford OX1 3QZ, United Kingdom
| | - Limeng Ni
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Qifei Gu
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Aditya Sadhanala
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Akshay Rao
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Philipp Kukura
- Physical
and Theoretical Chemistry Laboratory, University
of Oxford, South Parks
Road, Oxford OX1 3QZ, United Kingdom
- E-mail:
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223
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Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
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Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
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224
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Ito S, Nagami T, Nakano M. Diradical Character-Based Design for Singlet Fission of Bisanthene Derivatives: Aromatic-Ring Attachment and π-Plane Twisting. J Phys Chem Lett 2016; 7:3925-3930. [PMID: 27653705 DOI: 10.1021/acs.jpclett.6b01885] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate a diradical character-based molecular design for singlet fission using polycyclic aromatic hydrocarbons, bisanthene derivatives. Two types of chemical modifications-aromatic-ring attachment and π-plane twisting-are examined in order to satisfy the energy level matching condition for singlet fission. Detailed analysis of the electronic structures of the model molecules using nucleus-independent chemical shift, molecular orbitals, and their energies has demonstrated the usefulness of the relationship between the resonance structure and aromaticity and that between nonplanarity of π-conjugated systems and reduction of orbital overlap for tuning the diradical character. This result provides a novel design guideline for polycyclic aromatic hydrocarbons toward efficient singlet fission.
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Affiliation(s)
- Soichi Ito
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan
| | - Takanori Nagami
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan
| | - Masayoshi Nakano
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan
- Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan
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225
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Feng X, Krylov AI. On couplings and excimers: lessons from studies of singlet fission in covalently linked tetracene dimers. Phys Chem Chem Phys 2016; 18:7751-61. [PMID: 26910414 DOI: 10.1039/c6cp00177g] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Electronic factors controlling singlet fission (SF) rates are investigated in covalently linked dimers of tetracene. Using covalent linkers, relative orientation of the individual chromophores can be controlled, maximizing the rates of SF. Structures with coplanar and staggered arrangements of tetracene moieties are considered. The electronic structure calculations and three-state kinetic model for SF rates provide explanations for experimentally observed low SF yields in coplanar dimers and efficient SF in staggered dimers. The calculations illuminate the role of the excimer formation in SF process. The structural relaxation in the S1 state leads to the increased rate of the multi-exciton (ME) state formation, but impedes the second step, separation of the ME state into independent triplets. The slower second step reduces SF yield by allowing other processes, such as radiationless relaxation, to compete with triplet generation. The calculations of electronic couplings also suggest an increased rate of radiationless relaxation at the excimer geometries. Thus, the excimer serves as a trap of the ME state. The effect of covalent linkers on the electronic factors and SF rates is investigated. In all considered structures, the presence of the linker leads to larger couplings, however, the effect on the overall rate is less straightforward, since the linkers generally result in less favorable energetics. This complex behavior once again illustrates the importance of integrative approaches that evaluate the overall rate, rather than focusing on specific electronic factors such as energies or couplings.
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Affiliation(s)
- Xintian Feng
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA.
| | - Anna I Krylov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA.
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226
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Zhu T, Wan Y, Guo Z, Johnson J, Huang L. Two Birds with One Stone: Tailoring Singlet Fission for Both Triplet Yield and Exciton Diffusion Length. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:7539-7547. [PMID: 27348847 DOI: 10.1002/adma.201600968] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/04/2016] [Indexed: 06/06/2023]
Abstract
By direct imaging of singlet and triplet populations with ultrafast microscopy, it is shown that the triplet diffusion length and singlet fission yield can be simultaneously optimized for tetracene and its derivatives, making them ideal structures for application in bilayer solar cells.
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Affiliation(s)
- Tong Zhu
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Yan Wan
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Zhi Guo
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Justin Johnson
- National Renewable Energy Laboratory, 15013 Denver West Pkwy, Golden, CO, 80401, USA
| | - Libai Huang
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA.
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227
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Mauck CM, Hartnett PE, Margulies EA, Ma L, Miller CE, Schatz GC, Marks TJ, Wasielewski MR. Singlet Fission via an Excimer-Like Intermediate in 3,6-Bis(thiophen-2-yl)diketopyrrolopyrrole Derivatives. J Am Chem Soc 2016; 138:11749-61. [PMID: 27547986 DOI: 10.1021/jacs.6b05627] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Singlet fission (SF) in polycrystalline thin films of four 3,6-bis(thiophen-2-yl)diketopyrrolopyrrole (TDPP) chromophores with methyl (Me), n-hexyl (C6), triethylene glycol (TEG), and 2-ethylhexyl (EH) substituents at the 2,5-positions is found to involve an intermediate excimer-like state. The four different substituents yield four distinct intermolecular packing geometries, resulting in variable intermolecular charge transfer (CT) interactions in the solid. SF from the excimer state of Me, C6, TEG, and EH takes place in τSF = 22, 336, 195, and 1200 ps, respectively, to give triplet yields of 200%, 110%, 110%, and 70%, respectively. The transient spectra of the excimer-like state and its energetic proximity to the lowest excited singlet state in these derivatives suggests that this state may be the multiexciton (1)(T1T1) state that precedes formation of the uncorrelated triplet excitons. The excimer decay rates correlate well with the SF efficiencies and the degree of intermolecular donor-acceptor interactions resulting from π-stacking of the thiophene donor of one molecule with the DPP core acceptor in another molecule as observed in the crystal structures. Such interactions are found to also increase with the SF coupling energies, as calculated for each derivative. These structural and spectroscopic studies afford a better understanding of the electronic interactions that enhance SF in chromophores having strong intra- and intermolecular CT character.
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Affiliation(s)
- Catherine M Mauck
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Patrick E Hartnett
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Eric A Margulies
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Lin Ma
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Claire E Miller
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - George C Schatz
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Tobin J Marks
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Michael R Wasielewski
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
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228
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Margulies EA, Miller CE, Wu Y, Ma L, Schatz GC, Young RM, Wasielewski MR. Enabling singlet fission by controlling intramolecular charge transfer in π-stacked covalent terrylenediimide dimers. Nat Chem 2016; 8:1120-1125. [PMID: 27874873 DOI: 10.1038/nchem.2589] [Citation(s) in RCA: 192] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 07/01/2016] [Indexed: 01/05/2023]
Abstract
When an assembly of two or more molecules absorbs a photon to form a singlet exciton, and the energetics and intermolecular interactions are favourable, the singlet exciton can rapidly and spontaneously produce two triplet excitons by singlet fission. To understand this process is important because it may prove to be technologically significant for enhancing solar-cell performance. Theory strongly suggests that charge-transfer states are involved in singlet fission, but their role has remained an intriguing puzzle and, up until now, no molecular system has provided clear evidence for such a state. Here we describe a terrylenediimide dimer that forms a charge-transfer state in a few picoseconds in polar solvents, and undergoes equally rapid, high-yield singlet fission in nonpolar solvents. These results show that adjusting the charge-transfer-state energy relative to those of the exciton states can serve to either inhibit or promote singlet fission.
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Affiliation(s)
- Eric A Margulies
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Claire E Miller
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Yilei Wu
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Lin Ma
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - George C Schatz
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Ryan M Young
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Michael R Wasielewski
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
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229
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Mayhall NJ. From Model Hamiltonians to ab Initio Hamiltonians and Back Again: Using Single Excitation Quantum Chemistry Methods To Find Multiexciton States in Singlet Fission Materials. J Chem Theory Comput 2016; 12:4263-73. [DOI: 10.1021/acs.jctc.6b00545] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Nicholas J. Mayhall
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24060, United States
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230
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Yost SR, Head-Gordon M. Size consistent formulations of the perturb-then-diagonalize Møller-Plesset perturbation theory correction to non-orthogonal configuration interaction. J Chem Phys 2016; 145:054105. [DOI: 10.1063/1.4959794] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Shane R. Yost
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Martin Head-Gordon
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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231
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Ito S, Nagami T, Nakano M. Design Principles of Electronic Couplings for Intramolecular Singlet Fission in Covalently-Linked Systems. J Phys Chem A 2016; 120:6236-41. [DOI: 10.1021/acs.jpca.6b07153] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Soichi Ito
- Department
of Materials Engineering
Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Takanori Nagami
- Department
of Materials Engineering
Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Masayoshi Nakano
- Department
of Materials Engineering
Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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232
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Pensack RD, Ostroumov EE, Tilley AJ, Mazza S, Grieco C, Thorley KJ, Asbury JB, Seferos DS, Anthony JE, Scholes GD. Observation of Two Triplet-Pair Intermediates in Singlet Exciton Fission. J Phys Chem Lett 2016; 7:2370-5. [PMID: 27281713 DOI: 10.1021/acs.jpclett.6b00947] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Singlet fission is an excitation multiplication process in molecular systems that can circumvent energy losses and significantly boost solar cell efficiencies; however, the nature of a critical intermediate that enables singlet fission and details of its evolution into multiple product excitations remain obscure. We resolve the initial sequence of events comprising the fission of a singlet exciton in solids of pentacene derivatives using femtosecond transient absorption spectroscopy. We propose a three-step model of singlet fission that includes two triplet-pair intermediates and show how transient spectroscopy can distinguish initially interacting triplet pairs from those that are spatially separated and noninteracting. We find that the interconversion of these two triplet-pair intermediates is limited by the rate of triplet transfer. These results clearly highlight the classical kinetic model of singlet fission and expose subtle details that promise to aid in resolving problems associated with triplet extraction.
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Affiliation(s)
- Ryan D Pensack
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Evgeny E Ostroumov
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Andrew J Tilley
- Department of Chemistry, University of Toronto , Toronto, Ontario M5S 3H6, Canada
| | - Samuel 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
| | - Karl J Thorley
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
| | - John B Asbury
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Dwight S Seferos
- Department of Chemistry, University of Toronto , Toronto, Ontario M5S 3H6, Canada
| | - John E Anthony
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
| | - Gregory D Scholes
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
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233
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Cook JD, Carey TJ, Damrauer NH. Solution-Phase Singlet Fission in a Structurally Well-Defined Norbornyl-Bridged Tetracene Dimer. J Phys Chem A 2016; 120:4473-81. [PMID: 27291516 DOI: 10.1021/acs.jpca.6b04367] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photophysics of a norbornyl-bridged covalent tetracene (Tc) dimer BT1 and a monomer analogue Tc-e were studied in room-temperature nonpolar solvents. Notably in BT1, a Davydov-split band is observed in UV absorption, heralding interchromophore electronic interactions. Emission spectra indicate an acene-like vibronic progression mirroring the lowest-energy visible absorption. For BT1, this argues against excited-state excimer formation. Evidence of intramolecular singlet fission (SF) comes from a comparison of time-resolved emission decay signals collected for BT1 versus Tc-e in toluene. In BT1, the multiexcitonic (1)TT state is produced in 70 ns in 6% yield. A ratio of fission versus fusion rate constants provides an experimental measure of the SF reaction free energy at 52 meV in good agreement with previous calculations. The low SF yield corroborates our expectations that orbital symmetry effects on diabatic coupling for SF are important for dimers that cannot rely on more favorable thermodynamics.
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Affiliation(s)
- Jasper D Cook
- Department of Chemistry and Biochemistry, University of Colorado , Boulder Colorado 80309, United States
| | - Thomas J Carey
- Department of Chemistry and Biochemistry, University of Colorado , Boulder Colorado 80309, United States
| | - Niels H Damrauer
- Department of Chemistry and Biochemistry, University of Colorado , Boulder Colorado 80309, United States
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234
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Sanders SN, Kumarasamy E, Pun AB, Appavoo K, Steigerwald ML, Campos LM, Sfeir MY. Exciton Correlations in Intramolecular Singlet Fission. J Am Chem Soc 2016; 138:7289-97. [DOI: 10.1021/jacs.6b00657] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Samuel N. Sanders
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Elango Kumarasamy
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Andrew B. Pun
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Kannatassen Appavoo
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
| | | | - Luis M. Campos
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Matthew Y. Sfeir
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
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235
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Fuemmeler EG, Sanders SN, Pun A, Kumarasamy E, Zeng T, Miyata K, Steigerwald ML, Zhu XY, Sfeir MY, Campos LM, Ananth N. A Direct Mechanism of Ultrafast Intramolecular Singlet Fission in Pentacene Dimers. ACS CENTRAL SCIENCE 2016; 2:316-24. [PMID: 27280166 PMCID: PMC4882733 DOI: 10.1021/acscentsci.6b00063] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Indexed: 05/05/2023]
Abstract
Interest in materials that undergo singlet fission (SF) has been catalyzed by the potential to exceed the Shockley-Queisser limit of solar power conversion efficiency. In conventional materials, the mechanism of SF is an intermolecular process (xSF), which is mediated by charge transfer (CT) states and depends sensitively on crystal packing or molecular collisions. In contrast, recently reported covalently coupled pentacenes yield ∼2 triplets per photon absorbed in individual molecules: the hallmark of intramolecular singlet fission (iSF). However, the mechanism of iSF is unclear. Here, using multireference electronic structure calculations and transient absorption spectroscopy, we establish that iSF can occur via a direct coupling mechanism that is independent of CT states. We show that a near-degeneracy in electronic state energies induced by vibronic coupling to intramolecular modes of the covalent dimer allows for strong mixing between the correlated triplet pair state and the local excitonic state, despite weak direct coupling.
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Affiliation(s)
- Eric G. Fuemmeler
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
| | - Samuel N. Sanders
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Andrew
B. Pun
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Elango Kumarasamy
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Tao Zeng
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
| | - Kiyoshi Miyata
- 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
| | - Matthew Y. Sfeir
- Center
for Functional Nanomaterials, Brookhaven
National Laboratory, Upton, New York 11973, United States
- E-mail:
| | - Luis M. Campos
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
- E-mail:
| | - Nandini Ananth
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
- E-mail:
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236
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Zirzlmeier J, Casillas R, Reddy SR, Coto PB, Lehnherr D, Chernick ET, Papadopoulos I, Thoss M, Tykwinski RR, Guldi DM. Solution-based intramolecular singlet fission in cross-conjugated pentacene dimers. NANOSCALE 2016; 8:10113-23. [PMID: 27122097 DOI: 10.1039/c6nr02493a] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We show unambiguous and compelling evidence by means of pump-probe experiments, which are complemented by calculations using ab initio multireference perturbation theory, for intramolecular singlet fission (SF) within two synthetically tailored pentacene dimers with cross-conjugation, namely XC1 and XC2. The two pentacene dimers differ in terms of electronic interactions as evidenced by perturbation of the ground state absorption spectra stemming from stronger through-bond contributions in XC1 as confirmed by theory. Multiwavelength analysis, on one hand, and global analysis, on the other hand, confirm that the rapid singlet excited state decay and triplet excited state growth relate to SF. SF rate constants and quantum yields increase with solvent polarity. For example, XC2 reveals triplet quantum yields and rate constants as high as 162 ± 10% and (0.7 ± 0.1) × 10(12) s(-1), respectively, in room temperature solutions.
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Affiliation(s)
- Johannes Zirzlmeier
- Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), Engineering of Advanced Materials (EAM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 3, 91058 Erlangen, Germany.
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237
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Kato D, Sakai H, Tkachenko NV, Hasobe T. High-Yield Excited Triplet States in Pentacene Self-Assembled Monolayers on Gold Nanoparticles through Singlet Exciton Fission. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201601421] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Daiki Kato
- Department of Chemistry; Faculty of Science and Technology; Keio University; Yokohama Kanagawa 223-8522 Japan
| | - Hayato Sakai
- Department of Chemistry; Faculty of Science and Technology; Keio University; Yokohama Kanagawa 223-8522 Japan
| | - Nikolai V. Tkachenko
- Department of Chemistry and Bioengineering; Tampere University of Technology; P.O. Box 541 33101 Tampere Finland
| | - Taku Hasobe
- Department of Chemistry; Faculty of Science and Technology; Keio University; Yokohama Kanagawa 223-8522 Japan
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238
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Kato D, Sakai H, Tkachenko NV, Hasobe T. High-Yield Excited Triplet States in Pentacene Self-Assembled Monolayers on Gold Nanoparticles through Singlet Exciton Fission. Angew Chem Int Ed Engl 2016; 55:5230-4. [DOI: 10.1002/anie.201601421] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Daiki Kato
- Department of Chemistry; Faculty of Science and Technology; Keio University; Yokohama Kanagawa 223-8522 Japan
| | - Hayato Sakai
- Department of Chemistry; Faculty of Science and Technology; Keio University; Yokohama Kanagawa 223-8522 Japan
| | - Nikolai V. Tkachenko
- Department of Chemistry and Bioengineering; Tampere University of Technology; P.O. Box 541 33101 Tampere Finland
| | - Taku Hasobe
- Department of Chemistry; Faculty of Science and Technology; Keio University; Yokohama Kanagawa 223-8522 Japan
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239
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Sakuma T, Sakai H, Araki Y, Mori T, Wada T, Tkachenko NV, Hasobe T. Long-Lived Triplet Excited States of Bent-Shaped Pentacene Dimers by Intramolecular Singlet Fission. J Phys Chem A 2016; 120:1867-75. [PMID: 26930127 DOI: 10.1021/acs.jpca.6b00988] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Intramolecular singlet fission (ISF) is a promising photophysical process to construct more efficient light energy conversion systems as one excited singlet state converts into two excited triplet states. Herein we synthesized and evaluated bent-shaped pentacene dimers as a prototype of ISF to reveal intrinsic characters of triplet states (e.g., lifetimes of triplet excited states). In this study, meta-phenylene-bridged TIPS-pentacene dimer (PcD-3Ph) and 2,2'-bipheynyl bridged TIPS-pentacene dimer (PcD-Biph) were newly synthesized as bent-shaped dimers. In the steady-state spectroscopy, absorption and emission bands of these dimers were fully characterized, suggesting the appropriate degree of electronic coupling between pentacene moieties in these dimers. In addition, the electrochemical measurements were also performed to check the electronic interaction between two pentacene moieties. Whereas the successive two oxidation peaks owing to the delocalization were observed in a directly linked-pentacene dimer (PcD) by a single bond, the cyclic voltammograms in PcD-Biph and PcD-3Ph implied the weaker interaction compared to that of p-phenylene-bridged TIPS-pentacene dimer (PcD-4Ph) and PcD. The femtosecond and nanosecond transient absorption spectra clearly revealed the slower ISF process in bent-shaped pentacene dimers (PcD-Biph and PcD-3Ph), more notably, the slower relaxation of the excited triplet states in PcD-Biph and PcD-3Ph. Namely, the quantum yields of triplet states (ΦT) by ISF approximately remain constant (ca. 180-200%) in all dimer systems, whereas the lifetimes of the triplet excited states became much longer (up to 360 ns) in PcD-Biph as compared to PcD-4Ph (15 ns). Additionally, the lifetimes of the corresponding triplet states in PcD-Biph and PcD-3Ph were sufficiently affected by solvent viscosity. In particular, the lifetimes of PcD-Biph triplet state in THF/paraffin (1.0 μs) increased up to approximately three times as compared to that in THF (360 ns), whereas those of PcD-4Ph were quite similar in both solvent.
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Affiliation(s)
- Takao Sakuma
- Department of Chemistry, Faculty of Science and Technology, Keio University , Yokohama, 223-8522, Japan
| | - Hayato Sakai
- Department of Chemistry, Faculty of Science and Technology, Keio University , Yokohama, 223-8522, Japan
| | - Yasuyuki Araki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Tadashi Mori
- Department of Applied Chemistry, Osaka University , 2-1 Yamada-oka, Suita 565-0871, Japan
| | - Takehiko Wada
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Nikolai V Tkachenko
- Department of Chemistry and Bioengineering, Tampere University of Technology , 33720 Tampere, Finland
| | - Taku Hasobe
- Department of Chemistry, Faculty of Science and Technology, Keio University , Yokohama, 223-8522, Japan
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240
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Kawata S, Pu YJ, Saito A, Kurashige Y, Beppu T, Katagiri H, Hada M, Kido J. Singlet Fission of Non-polycyclic Aromatic Molecules in Organic Photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:1585-1590. [PMID: 26663207 DOI: 10.1002/adma.201504281] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/14/2015] [Indexed: 06/05/2023]
Abstract
Singlet fission of thienoquinoid compounds in organic photovoltaics is demonstrated. The escalation of the thienoquinoid length of the compounds realizes a suitable packing structure and energy levels for singlet fission. The magnetic-field dependence of the photocurrent and the external quantum efficiency of the devices reveal singlet fission of the compounds and dissociation of triplet excitons into charges.
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Affiliation(s)
- So Kawata
- Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Yong-Jin Pu
- Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
- JST-PRESTO, Kawaguchi, Saitama, 332-0012, Japan
| | - Ayaka Saito
- Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Yuki Kurashige
- JST-PRESTO, Kawaguchi, Saitama, 332-0012, Japan
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi, 444-8585, Japan
| | - Teruo Beppu
- Department of Chemistry and Chemical Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Hiroshi Katagiri
- Department of Chemistry and Chemical Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Masaki Hada
- JST-PRESTO, Kawaguchi, Saitama, 332-0012, Japan
- Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan
| | - Junji Kido
- Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
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241
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Fujihashi Y, Ishizaki A. Fluctuations in Electronic Energy Affecting Singlet Fission Dynamics and Mixing with Charge-Transfer State: Quantum Dynamics Study. J Phys Chem Lett 2016; 7:363-369. [PMID: 26732701 DOI: 10.1021/acs.jpclett.5b02678] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Singlet fission is a spin-allowed process by which a singlet excited state is converted to two triplet states. To understand mechanisms of the ultrafast fission via a charge transfer (CT) state, one has investigated the dynamics through quantum-dynamical calculations with the uncorrelated fluctuation model; however, the electronic states are expected to experience the same fluctuations induced by the surrounding molecules because the electronic structure of the triplet pair state is similar to that of the singlet state except for the spin configuration. Therefore, the fluctuations in the electronic energies could be correlated, and the 1D reaction coordinate model may adequately describe the fission dynamics. In this work we develop a model for describing the fission dynamics to explain the experimentally observed behaviors. We also explore impacts of fluctuations in the energy of the CT state on the fission dynamics and the mixing with the CT state. The overall behavior of the dynamics is insensitive to values of the reorganization energy associated with the transition from the singlet state to the CT state, although the coherent oscillation is affected by the fluctuations. This result indicates that the mixing with the CT state is rather robust under the fluctuations in the energy of the CT state as well as the high-lying CT state.
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Affiliation(s)
- Yuta Fujihashi
- Institute for Molecular Science, National Institutes of Natural Sciences , Okazaki 444-8585, Japan
| | - Akihito Ishizaki
- Institute for Molecular Science, National Institutes of Natural Sciences , Okazaki 444-8585, Japan
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242
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Sanders SN, Kumarasamy E, Pun AB, Steigerwald ML, Sfeir MY, Campos LM. Intramolecular Singlet Fission in Oligoacene Heterodimers. Angew Chem Int Ed Engl 2016; 55:3373-7. [DOI: 10.1002/anie.201510632] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Samuel N. Sanders
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Elango Kumarasamy
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Andrew B. Pun
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Michael L. Steigerwald
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Matthew Y. Sfeir
- Center for Functional Nanomaterials; Brookhaven National Laboratory; Building 735 Upton NY 11973 USA
| | - Luis M. Campos
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
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243
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Sanders SN, Kumarasamy E, Pun AB, Steigerwald ML, Sfeir MY, Campos LM. Intramolecular Singlet Fission in Oligoacene Heterodimers. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510632] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Samuel N. Sanders
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Elango Kumarasamy
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Andrew B. Pun
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Michael L. Steigerwald
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Matthew Y. Sfeir
- Center for Functional Nanomaterials; Brookhaven National Laboratory; Building 735 Upton NY 11973 USA
| | - Luis M. Campos
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
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244
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Korovina NV, Das S, Nett Z, Feng X, Joy J, Haiges R, Krylov AI, Bradforth SE, Thompson ME. Singlet Fission in a Covalently Linked Cofacial Alkynyltetracene Dimer. J Am Chem Soc 2016; 138:617-27. [PMID: 26693957 DOI: 10.1021/jacs.5b10550] [Citation(s) in RCA: 185] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Singlet fission is a process in which a singlet exciton converts into two triplet excitons. To investigate this phenomenon, we synthesized two covalently linked 5-ethynyl-tetracene (ET) dimers with differing degrees of intertetracene overlap: BET-X, with large, cofacial overlap of tetracene π-orbitals, and BET-B, with twisted arrangement between tetracenes exhibits less overlap between the tetracene π-orbitals. The two compounds were crystallographically characterized and studied by absorption and emission spectroscopy in solution, in PMMA and neat thin films. The results show that singlet fission occurs within 1 ps in an amorphous thin film of BET-B with high efficiency (triplet yield: 154%). In solution and the PMMA matrix the S1 of BET-B relaxes to a correlated triplet pair (1)(T1T1) on a time scale of 2 ps, which decays to the ground state without forming separated triplets, suggesting that triplet energy transfer from (1)(T1T1) to a nearby chromophore is essential for producing free triplets. In support of this hypothesis, selective excitation of BET-B doped into a thin film of diphenyltetracene (DPT) leads to formation of the (1)(T1T1) state of BET-B, followed by generation of both DPT and BET-B triplets. For the structurally cofacial BET-X, an intermediate forms in <180 fs and returns to the ground state more rapidly than BET-B. First-principles calculations predict a 2 orders of magnitude faster rate of singlet fission to the (1)(T1T1) state in BET-B relative to that of crystalline tetracene, attributing the rate increase to greater coupling between the S1 and (1)(T1T1) states and favorable energetics for formation of the separated triplets.
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Affiliation(s)
- Nadezhda V Korovina
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Saptaparna Das
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Zachary Nett
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Xintian Feng
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Jimmy Joy
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Ralf Haiges
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Anna I Krylov
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Stephen E Bradforth
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Mark E Thompson
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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245
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Ishibashi Y, Inoue Y, Asahi T. The excitation intensity dependence of singlet fission dynamics of a rubrene microcrystal studied by femtosecond transient microspectroscopy. Photochem Photobiol Sci 2016; 15:1304-1309. [DOI: 10.1039/c6pp00171h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
When a rubrene crystal was excited with an intense fs pulse (397 nm), transient local heating (∼ps) of the crystal through nonradiative relaxation from SN to S1 accelerates singlet fission of the S1.
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Affiliation(s)
- Y. Ishibashi
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama
- Japan
| | - Y. Inoue
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama
- Japan
| | - T. Asahi
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama
- Japan
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246
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Yanai N, Kimizuka N. Recent emergence of photon upconversion based on triplet energy migration in molecular assemblies. Chem Commun (Camb) 2016; 52:5354-70. [DOI: 10.1039/c6cc00089d] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This Feature Article reviews an emerging field of triplet energy migration-based photon upconversion (TEM-UC) that allows highly efficient photon upconversion at low excitation power.
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Affiliation(s)
- Nobuhiro Yanai
- Department of Chemistry and Biochemistry
- Graduate School of Engineering
- Center for Molecular Systems (CMS)
- Kyushu University
- Nishi-ku
| | - Nobuo Kimizuka
- Department of Chemistry and Biochemistry
- Graduate School of Engineering
- Center for Molecular Systems (CMS)
- Kyushu University
- Nishi-ku
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247
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Leng X, Feng J, Chen T, Liu C, Ma Y. Optical properties of acene molecules and pentacene crystal from the many-body Green's function method. Phys Chem Chem Phys 2016; 18:30777-30784. [DOI: 10.1039/c6cp05902c] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using many-body Green's function theory, we compare the excitation of several acene molecules at geometries optimized by different approaches.
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Affiliation(s)
- Xia Leng
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan 250100
- China
| | - Jin Feng
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan 250100
- China
| | - Tingwei Chen
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan 250100
- China
| | - Chengbu Liu
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan 250100
- China
| | - Yuchen Ma
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan 250100
- China
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248
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Scholes GD. Correlated Pair States Formed by Singlet Fission and Exciton–Exciton Annihilation. J Phys Chem A 2015; 119:12699-705. [DOI: 10.1021/acs.jpca.5b09725] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gregory D. Scholes
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
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249
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Damrauer NH, Snyder JL. Symmetry-directed control of electronic coupling for singlet fission in covalent bis-acene dimers. J Phys Chem Lett 2015; 6:4456-4462. [PMID: 26505732 DOI: 10.1021/acs.jpclett.5b02186] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
While singlet fission (SF) has developed in recent years within material settings, much less is known about its control in covalent dimers. Such platforms are of fundamental importance and may also find practical use in next-generation dye-sensitized solar cell applications or for seeding SF at interfaces following exciton transport. Here, facile theoretical tools based on Boys localization methods are used to predict diabatic coupling for SF via determination of one-electron orbital coupling matrix elements. The results expose important design rules that are rooted in point group symmetry. For Cs-symmetric dimers, pathways for SF that are mediated by virtual charge transfer excited states destructively interfere with negative impact on the magnitude of diabatic coupling for SF. When dimers have C2 symmetry, constructive interference is enabled for certain readily achievable interchromophore orientations. Three sets of dimers exploiting these ideas are explored: a bis-tetracene pair and two sets of aza-substituted tetracene dimers. Remarkable control is shown. In one aza-substituted set, symmetry has no impact on SF reaction thermodynamics but leads to a 16-fold manipulation in SF diabatic coupling. This translates to a difference of nearly 300 in kSF with the faster of the two dimers (C2) being predicted to undergo the process on a nearly ultrafast 1.5 ps time scale.
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Affiliation(s)
- Niels H Damrauer
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - Jamie L Snyder
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
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250
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Teichen PE, Eaves JD. Collective aspects of singlet fission in molecular crystals. J Chem Phys 2015; 143:044118. [PMID: 26233118 DOI: 10.1063/1.4922644] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We present a model to describe collective features of singlet fission in molecular crystals and analyze it using many-body theory. The model we develop allows excitonic states to delocalize over several chromophores which is consistent with the character of the excited states in many molecular crystals, such as the acenes, where singlet fission occurs. As singlet states become more delocalized and triplet states more localized, the rate of singlet fission increases. We also determine the conditions under which the two triplets resulting from fission are correlated. Using the Bethe Ansatz and an entanglement measure for indistinguishable bipartite systems, we calculate the triplet-triplet entanglement as a function of the biexciton interaction strength. The biexciton interaction can produce bound biexciton states and provides a source of entanglement between the two triplets even when the triplets are spatially well separated. Significant entanglement between the triplet pair occurs well below the threshold for bound pair formation. Our results paint a dynamical picture that helps to explain why fission has been observed to be more efficient in molecular crystals than in their covalent dimer analogues and have consequences for photovoltaic efficiency models that assume that the two triplets can be extracted independently.
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Affiliation(s)
- Paul E Teichen
- Department of Chemistry and Biochemistry, The University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Joel D Eaves
- Department of Chemistry and Biochemistry, The University of Colorado at Boulder, Boulder, Colorado 80309, USA
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