151
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Ribeiro RF, Martínez-Martínez LA, Du M, Campos-Gonzalez-Angulo J, Yuen-Zhou J. Polariton chemistry: controlling molecular dynamics with optical cavities. Chem Sci 2018; 9:6325-6339. [PMID: 30310561 PMCID: PMC6115696 DOI: 10.1039/c8sc01043a] [Citation(s) in RCA: 259] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 06/07/2018] [Indexed: 12/16/2022] Open
Abstract
Molecular polaritons are the optical excitations which emerge when molecular transitions interact strongly with confined electromagnetic fields. Increasing interest in the hybrid molecular-photonic materials that host these excitations stems from recent observations of their novel and tunable chemistry. Some of the remarkable functionalities exhibited by polaritons include the ability to induce long-range excitation energy transfer, enhance charge conductivity, and inhibit or accelerate chemical reactions. In this review, we explain the effective theories of molecular polaritons which form a basis for the interpretation and guidance of experiments at the strong coupling limit. The theoretical discussion is illustrated with the analysis of innovative applications of strongly coupled molecular-photonic systems to chemical phenomena of fundamental importance to future technologies.
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Affiliation(s)
- Raphael F Ribeiro
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , USA .
| | - Luis A Martínez-Martínez
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , USA .
| | - Matthew Du
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , USA .
| | - Jorge Campos-Gonzalez-Angulo
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , USA .
| | - Joel Yuen-Zhou
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , USA .
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152
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Korovina NV, Joy J, Feng X, Feltenberger C, Krylov AI, Bradforth SE, Thompson ME. Linker-Dependent Singlet Fission in Tetracene Dimers. J Am Chem Soc 2018; 140:10179-10190. [PMID: 30016102 DOI: 10.1021/jacs.8b04401] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Separation of triplet excitons produced by singlet fission is crucial for efficient application of singlet fission materials. While earlier works explored the first step of singlet fission, the formation of the correlated triplet pair state, the focus of recent studies has been on understanding the second step of singlet fission, the formation of independent triplets from the correlated pair state. We present the synthesis and excited-state dynamics of meta- and para-bis(ethynyltetracenyl)benzene dimers that are analogues to the ortho-bis(ethynyltetracenyl)benzene dimer reported by our groups previously. A comparison of the excited-state properties of these dimers allows us to investigate the effects of electronic conjugation and coupling on singlet fission between the ethynyltetracene units within a dimer. In the para isomer, in which the two chromophores are conjugated, the singlet exciton yields the correlated triplet pair state, from which the triplet excitons can decouple via molecular rotations. In contrast, the meta isomer in which the two chromophores are cross-coupled predominantly relaxes via radiative decay. We also report the synthesis and excited-state dynamics of two para dimers with different bridging units joining the ethynyltetracenes. The rate of singlet fission is found to be faster in the dimer with the bridging unit that has orbitals closer in energy to that of the ethynyltetracene chromophores.
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Affiliation(s)
- Nadezhda V Korovina
- 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
| | - Xintian Feng
- Department of Chemistry , University of Southern California , Los Angeles , California 90089 , United States
| | - Cassidy Feltenberger
- 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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153
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Hu J, Xu K, Shen L, Wu Q, He G, Wang JY, Pei J, Xia J, Sfeir MY. New insights into the design of conjugated polymers for intramolecular singlet fission. Nat Commun 2018; 9:2999. [PMID: 30065295 PMCID: PMC6068183 DOI: 10.1038/s41467-018-05389-w] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 06/28/2018] [Indexed: 11/09/2022] Open
Abstract
Singlet fission (SF), a multiple exciton generation process that generates two triplet excitons after the absorption of one photon, can potentially enable more efficient solar cell designs by harvesting energy normally lost as heat. While low-bandgap conjugated polymers are highly promising candidates for efficient SF-based solar cells, few polymer materials capable of SF have been reported because the SF process in polymer chains is poorly understood. Using transient spectroscopy, we demonstrate a new, highly efficient (triplet yield of 160-200%) isoindigo-based donor-acceptor polymer and show that the triplet pairs are directly emissive and exhibit a time-dependent energy evolution. Importantly, aggregation in poor solvents and in films significantly lowers the singlet energy, suppressing triplet formation because the energy conservation criterion is no longer met. These results suggest a new design rule for developing intramolecular SF capable low-bandgap conjugated polymers, whereby inter-chain interactions must be carefully engineered.
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Affiliation(s)
- Jiahua Hu
- School of Chemistry, Chemical Engineering and Life Science, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070, Wuhan, China
| | - Ke Xu
- School of Chemistry, Chemical Engineering and Life Science, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070, Wuhan, China
| | - Lei Shen
- School of Chemistry, Chemical Engineering and Life Science, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070, Wuhan, China
| | - Qin Wu
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Guiying He
- School of Chemistry, Chemical Engineering and Life Science, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070, Wuhan, China
| | - Jie-Yu Wang
- Beijing National Laboratory for Molecular Sciences (BNLMS), The Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Key Laboratory of Polymer Chemistry and Physics of Ministry of Education; Center of Soft Matter Science and Engineering; College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Jian Pei
- Beijing National Laboratory for Molecular Sciences (BNLMS), The Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; Key Laboratory of Polymer Chemistry and Physics of Ministry of Education; Center of Soft Matter Science and Engineering; College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Jianlong Xia
- School of Chemistry, Chemical Engineering and Life Science, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070, Wuhan, China.
| | - Matthew Y Sfeir
- School of Chemistry, Chemical Engineering and Life Science, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070, Wuhan, China.
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA.
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154
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Ghosh S, Verma P, Cramer CJ, Gagliardi L, Truhlar DG. Combining Wave Function Methods with Density Functional Theory for Excited States. Chem Rev 2018; 118:7249-7292. [PMID: 30044618 DOI: 10.1021/acs.chemrev.8b00193] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We review state-of-the-art electronic structure methods based both on wave function theory (WFT) and density functional theory (DFT). Strengths and limitations of both the wave function and density functional based approaches are discussed, and modern attempts to combine these two methods are presented. The challenges in modeling excited-state chemistry using both single-reference and multireference methods are described. Topics covered include background, combining density functional theory with single-configuration wave function theory, generalized Kohn-Sham (KS) theory, global hybrids, range-separated hybrids, local hybrids, using KS orbitals in many-body theory (including calculations of the self-energy and the GW approximation), Bethe-Salpeter equation, algorithms to accelerate GW calculations, combining DFT with multiconfigurational WFT, orbital-dependent correlation functionals based on multiconfigurational WFT, building multiconfigurational wave functions from KS configurations, adding correlation functionals to multiconfiguration self-consistent-field (MCSCF) energies, combining DFT with configuration-interaction singles by means of time-dependent DFT, using range separation to combine DFT with MCSCF, embedding multiconfigurational WFT in DFT, and multiconfiguration pair-density functional theory.
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Affiliation(s)
- Soumen Ghosh
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455-0431 , United States
| | - Pragya Verma
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455-0431 , United States
| | - Christopher J Cramer
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455-0431 , United States
| | - Laura Gagliardi
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455-0431 , United States
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455-0431 , United States
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155
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Wang Y, Ke Y, Zhao Y. The hierarchical and perturbative forms of stochastic Schrödinger equations and their applications to carrier dynamics in organic materials. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2018. [DOI: 10.1002/wcms.1375] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Yu‐Chen Wang
- State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Lab of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University Xiamen China
| | - Yaling Ke
- State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Lab of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University Xiamen China
| | - Yi Zhao
- State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Lab of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University Xiamen China
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156
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Lee TS, Lin YL, Kim H, Pensack RD, Rand BP, Scholes GD. Triplet Energy Transfer Governs the Dissociation of the Correlated Triplet Pair in Exothermic Singlet Fission. J Phys Chem Lett 2018; 9:4087-4095. [PMID: 29976063 DOI: 10.1021/acs.jpclett.8b01834] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Singlet fission is a spin-allowed process of exciton multiplication that has the potential to enhance the efficiency of photovoltaic devices. The majority of studies to date have emphasized understanding the first step of singlet fission, where the correlated triplet pair is produced. Here, we examine separation of correlated triplet pairs. We conducted temperature-dependent transient absorption on 6,3-bis(tri isopropylsilylethynyl)pentacene (TIPS-Pn) films, where singlet fission is exothermic. We evaluated time constants to show that their temperature dependence is inconsistent with an exclusively thermally activated process. Instead, we found that the trends can be modeled by a triplet-triplet energy transfer. The fitted reorganization energy and electronic coupling agree closely with values calculated using density matrix renormalization group quantum-chemical theory. We conclude that dissociation of the correlated triplet pair to separated (but spin-entangled) triplet excitons in TIPS-Pn occurs by triplet-triplet energy transfer with a hopping time constant of approximately 3.5 ps at room temperature.
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Affiliation(s)
- Tia S Lee
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - YunHui L Lin
- Department of Electrical Engineering , Princeton University , Princeton , New Jersey 08544 , United States
| | - Hwon Kim
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Ryan D Pensack
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Barry P Rand
- Department of Electrical Engineering , Princeton University , Princeton , New Jersey 08544 , United States
- Andlinger Center for Energy and the Environment , Princeton University , Princeton , New Jersey 08544 , United States
| | - Gregory D Scholes
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
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157
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158
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Nagata R, Nakanotani H, Potscavage WJ, Adachi C. Exploiting Singlet Fission in Organic Light-Emitting Diodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1801484. [PMID: 29974520 DOI: 10.1002/adma.201801484] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/06/2018] [Indexed: 06/08/2023]
Abstract
Harvesting of both triplets and singlets yields electroluminescence quantum efficiencies of nearly 100% in organic light-emitting diodes (OLEDs), but the production efficiency of excitons that can undergo radiative decay is theoretically limited to 100% of the electron-hole pairs. Here, breaking of this limit by exploiting singlet fission in an OLED is reported. Based on the dependence of electroluminescence intensity on an applied magnetic field, it is confirmed that triplets produced by singlet fission in a rubrene host matrix are emitted as near-infrared (NIR) electroluminescence by erbium(III) tris(8-hydroxyquinoline) (ErQ3 ) after excitonic energy transfer from the "dark" triplet state of rubrene to an "emissive" state of ErQ3 , leading to NIR electroluminescence with an overall exciton production efficiency of 100.8%. This demonstration clearly indicates that the harvesting of triplets produced by singlet fission as electroluminescence is possible even under electrical excitation, leading to an enhancement of the quantum efficiency of the OLEDs. Electroluminescence employing singlet fission provides a route toward developing high-intensity NIR light sources, which are of particular interest for sensing, optical communications, and medical applications.
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Affiliation(s)
- Ryo Nagata
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- JST, ERATO, Adachi Molecular Exciton Engineering Project, c/o Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Hajime Nakanotani
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- JST, ERATO, Adachi Molecular Exciton Engineering Project, c/o Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - William J Potscavage
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- JST, ERATO, Adachi Molecular Exciton Engineering Project, c/o Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- JST, ERATO, Adachi Molecular Exciton Engineering Project, c/o Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
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159
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Tempelaar R, Reichman DR. Vibronic exciton theory of singlet fission. III. How vibronic coupling and thermodynamics promote rapid triplet generation in pentacene crystals. J Chem Phys 2018; 148:244701. [DOI: 10.1063/1.5031778] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Roel Tempelaar
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - David R. Reichman
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
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160
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Sakai H, Inaya R, Nagashima H, Nakamura S, Kobori Y, Tkachenko NV, Hasobe T. Multiexciton Dynamics Depending on Intramolecular Orientations in Pentacene Dimers: Recombination and Dissociation of Correlated Triplet Pairs. J Phys Chem Lett 2018; 9:3354-3360. [PMID: 29847939 DOI: 10.1021/acs.jpclett.8b01184] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Pentacene dimers bridged by a phenylene at ortho and meta positions [denoted as o-(Pc)2 and m-(Pc)2] were synthesized to examine intramolecular orientation-dependent multiexciton dynamics, especially focusing on singlet fission (SF) and recombination from correlated triplet pairs [(TT)]. Absorption and electrochemical measurements indicated strong intramolecular couplings of o-(Pc)2 relative to m-(Pc)2. Femtosecond and nanosecond TA measurements successfully demonstrated efficient SF in both dimers. In contrast, the dissociation process from the (TT) to the individual triplets [(2 × T)] was clearly observed in m-(Pc)2, which is in sharp contrast to a major recombination process in o-(Pc)2. Time-resolved electron spin resonance (TR-ESR) measurements demonstrated that the recombination and dissociation proceed from the quintet state of 5(TT) in m-(Pc)2. The rate constant of the SF was 2 orders of magnitude greater in o-(Pc)2 than that in m-(Pc)2 and was rationalized by enhanced electronic coupling between adjacent HOMOs of the Pc units.
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Affiliation(s)
- Hayato Sakai
- Department of Chemistry , Faculty of Science and Technology, Keio University , Yokohama 223-8522 , Japan
| | - Ryutaro Inaya
- Department of Chemistry , Faculty of Science and Technology, Keio University , Yokohama 223-8522 , Japan
| | - Hiroki Nagashima
- Molecular Photoscience Research Center , Kobe University , 1-1 Rokkodai-cho , Nada-ku, Kobe 657-8501 , Japan
| | - Shunta Nakamura
- Department of Chemistry , Faculty of Science and Technology, Keio University , Yokohama 223-8522 , Japan
| | - Yasuhiro Kobori
- Molecular Photoscience Research Center , Kobe University , 1-1 Rokkodai-cho , Nada-ku, Kobe 657-8501 , Japan
- Department of Chemistry , Graduate School of Science, Kobe University , Kobe 657-8501 , Japan
| | - Nikolai V Tkachenko
- Laboratory 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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161
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Zeng T, Mellerup SK, Yang D, Wang X, Wang S, Stamplecoskie K. Identifying (BN) 2-pyrenes as a New Class of Singlet Fission Chromophores: Significance of Azaborine Substitution. J Phys Chem Lett 2018; 9:2919-2927. [PMID: 29763325 DOI: 10.1021/acs.jpclett.8b01226] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Singlet fission converts one photoexcited singlet state to two triplet excited states and raises photoelectric conversion efficiency in photovoltaic devices. However, only a handful of chromophores have been known to undergo this process, which greatly limits the application of singlet fission in photovoltaics. We hereby identify a recently synthesized diazadiborine-pyrene ((BN)2-pyrene) as a singlet fission chromophore. Theoretical calculations indicate that it satisfies the thermodynamics criteria for singlet fission. More importantly, the calculations provide a physical chemistry insight into how the BN substitution makes this happen. Both calculation and transient absorption spectroscopy experiments indicate that the chromophore has a better absorption than pentacene. The convenient synthesis pathway of the (BN)2-pyrene suggests an in situ chromophore generation in photovoltaic devices. Two more (BN)2-pyrene isomers are proposed as singlet fission chromophores. This study sets a step forward in the cross-link of singlet fission and azaborine chemistry.
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Affiliation(s)
- Tao Zeng
- Department of Chemistry , Carleton University , Ottawa , Ontario K1S5B6 , Canada
| | - Soren K Mellerup
- Department of Chemistry , Queen's University , Kingston , Ontario K7L3N6 , Canada
| | - Dengtao Yang
- Department of Chemistry , Queen's University , Kingston , Ontario K7L3N6 , Canada
| | - Xiang Wang
- Department of Chemistry , Queen's University , Kingston , Ontario K7L3N6 , Canada
| | - Suning Wang
- Department of Chemistry , Queen's University , Kingston , Ontario K7L3N6 , Canada
| | - Kevin Stamplecoskie
- Department of Chemistry , Queen's University , Kingston , Ontario K7L3N6 , Canada
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162
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Wang X, Liu X, Cook C, Schatschneider B, Marom N. On the possibility of singlet fission in crystalline quaterrylene. J Chem Phys 2018; 148:184101. [DOI: 10.1063/1.5027553] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Xiaopeng Wang
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Xingyu Liu
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Cameron Cook
- Department of Chemistry and Biochemistry, California State Polytechnic University at Pomona, Pomona, California 91768, USA
| | - Bohdan Schatschneider
- Department of Chemistry and Biochemistry, California State Polytechnic University at Pomona, Pomona, California 91768, USA
| | - Noa Marom
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
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163
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Basel BS, Zirzlmeier J, Hetzer C, Reddy SR, Phelan BT, Krzyaniak MD, Volland MK, Coto PB, Young RM, Clark T, Thoss M, Tykwinski RR, Wasielewski MR, Guldi DM. Evidence for Charge-Transfer Mediation in the Primary Events of Singlet Fission in a Weakly Coupled Pentacene Dimer. Chem 2018. [DOI: 10.1016/j.chempr.2018.04.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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164
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Martínez-Martínez LA, Du M, F Ribeiro R, Kéna-Cohen S, Yuen-Zhou J. Polariton-Assisted Singlet Fission in Acene Aggregates. J Phys Chem Lett 2018; 9:1951-1957. [PMID: 29551074 DOI: 10.1021/acs.jpclett.8b00008] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Singlet fission is an important candidate to increase energy conversion efficiency in organic photovoltaics by providing a pathway to increase the quantum yield of excitons per photon absorbed in select materials. We investigate the dependence of exciton quantum yield for acenes in the strong light-matter interaction (polariton) regime, where the materials are embedded in optical microcavities. Starting from an open-quantum-systems approach, we build a kinetic model for time-evolution of species of interest in the presence of singlet quenchers and show that polaritons can decrease or increase exciton quantum yields compared to the cavity-free case. In particular, we find that hexacene, under the conditions of our model, can feature a higher yield than cavity-free pentacene when assisted by polaritonic effects. Similarly, we show that pentacene yield can be increased when assisted by polariton states. Finally, we address how various relaxation processes between bright and dark states in lossy microcavities affect polariton photochemistry. Our results also provide insights on how to choose microcavities to enhance similarly related chemical processes.
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Affiliation(s)
- Luis A Martínez-Martínez
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , United States
| | - Matthew Du
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , United States
| | - Raphael F Ribeiro
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , United States
| | - Stéphane Kéna-Cohen
- Department of Engineering Physics , École Polytechnique de Montréal , Montréal H3C 3A7 , Quebec , Canada
| | - Joel Yuen-Zhou
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , United States
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165
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Sharifzadeh S. Many-body perturbation theory for understanding optical excitations in organic molecules and solids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:153002. [PMID: 29460855 DOI: 10.1088/1361-648x/aab0d1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Semiconductors composed of organic molecules are promising as components for flexible and inexpensive optoelectronic devices, with many recent studies aimed at understanding their electronic and optical properties. In particular, computational modeling of these complex materials has provided new understanding of the underlying properties which give rise to their excited-state phenomena. This article provides an overview of recent many-body perturbation theory (MBPT) studies of optical excitations within organic molecules and solids. We discuss the accuracy of MBPT within the GW/BSE approach in predicting excitation energies and absorption spectra, and assess the impact of two commonly used approximations, the DFT starting point and the Tamm-Dancoff approximation. Moreover, we summarize studies that elucidate the role of solid-state structure on the nature of excitons in organic crystals. These studies show that a rich physical understanding of organic materials can be obtained from GW/BSE.
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Affiliation(s)
- Sahar Sharifzadeh
- Division of Materials Science and Engineering, Department of Electrical and Computer Engineering, Department of Physics, Boston University, Boston, MA, United States of America
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166
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Hestand NJ, Spano FC. Expanded Theory of H- and J-Molecular Aggregates: The Effects of Vibronic Coupling and Intermolecular Charge Transfer. Chem Rev 2018; 118:7069-7163. [PMID: 29664617 DOI: 10.1021/acs.chemrev.7b00581] [Citation(s) in RCA: 700] [Impact Index Per Article: 116.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The electronic excited states of molecular aggregates and their photophysical signatures have long fascinated spectroscopists and theoreticians alike since the advent of Frenkel exciton theory almost 90 years ago. The influence of molecular packing on basic optical probes like absorption and photoluminescence was originally worked out by Kasha for aggregates dominated by Coulombic intermolecular interactions, eventually leading to the classification of J- and H-aggregates. This review outlines advances made in understanding the relationship between aggregate structure and photophysics when vibronic coupling and intermolecular charge transfer are incorporated. An assortment of packing geometries is considered from the humble molecular dimer to more exotic structures including linear and bent aggregates, two-dimensional herringbone and "HJ" aggregates, and chiral aggregates. The interplay between long-range Coulomb coupling and short-range charge-transfer-mediated coupling strongly depends on the aggregate architecture leading to a wide array of photophysical behaviors.
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Affiliation(s)
- Nicholas J Hestand
- Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Frank C Spano
- Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
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167
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Abstract
Singlet fission is a photophysical reaction in which a singlet excited electronic state splits into two spin-triplet states. Singlet fission was discovered more than 50 years ago, but the interest in this process has gained a lot of momentum in the past decade due to its potential as a way to boost solar cell efficiencies. This review presents and discusses the most recent advances with respect to the theoretical and computational studies on the singlet fission phenomenon. The work revisits important aspects regarding electronic states involved in the process, the evaluation of fission rates and interstate couplings, the study of the excited state dynamics in singlet fission, and the advances in the design and characterization of singlet fission compounds and materials such as molecular dimers, polymers, or extended structures. Finally, the review tries to pinpoint some aspects that need further improvement and proposes future lines of research for theoretical and computational chemists and physicists in order to further push the understanding and applicability of singlet fission.
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Affiliation(s)
- David Casanova
- Kimika Fakultatea , Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia International Physics Center (DIPC) , P.K. 1072, 20080 Donostia , Euskadi, Spain.,IKERBASQUE, Basque, Foundation for Science , 48013 Bilbao , Euskadi, Spain
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168
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Structure and dynamics of triplet-exciton pairs generated from singlet fission studied via magnetic field effects. Commun Chem 2018. [DOI: 10.1038/s42004-018-0008-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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169
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Pace NA, Arias DH, Granger DB, Christensen S, Anthony JE, Johnson JC. Dynamics of singlet fission and electron injection in self-assembled acene monolayers on titanium dioxide. Chem Sci 2018; 9:3004-3013. [PMID: 29732084 PMCID: PMC5915837 DOI: 10.1039/c7sc04688j] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/15/2018] [Indexed: 12/11/2022] Open
Abstract
We employ a combination of linear spectroscopy, electrochemistry, and transient absorption spectroscopy to characterize the interplay between electron transfer and singlet fission dynamics in polyacene-based dyes attached to nanostructured TiO2. For triisopropyl silylethynyl (TIPS)-pentacene, we find that the singlet fission time constant increases to 6.5 ps on a nanostructured TiO2 surface relative to a thin film time constant of 150 fs, and that triplets do not dissociate after they are formed. In contrast, TIPS-tetracene singlets quickly dissociate in 2 ps at the molecule/TiO2 interface, and this dissociation outcompetes the relatively slow singlet fission process. The addition of an alumina layer slows down electron injection, allowing the formation of triplets from singlet fission in 40 ps. However, the triplets do not inject electrons, which is likely due to a lack of sufficient driving force for triplet dissociation. These results point to the critical balance required between efficient singlet fission and appropriate energetics for interfacial charge transfer.
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Affiliation(s)
- Natalie A Pace
- National Renewable Energy Laboratory , Golden , CO 80401 , USA .
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , CO 80309 , USA
| | - Dylan H Arias
- National Renewable Energy Laboratory , Golden , CO 80401 , USA .
| | - Devin B Granger
- Department of Chemistry , University of Kentucky , Lexington , KY 40506 , USA
| | | | - John E Anthony
- Department of Chemistry , University of Kentucky , Lexington , KY 40506 , USA
| | - Justin C Johnson
- National Renewable Energy Laboratory , Golden , CO 80401 , USA .
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170
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Davis NJLK, Allardice JR, Xiao J, Petty AJ, Greenham NC, Anthony JE, Rao A. Singlet Fission and Triplet Transfer to PbS Quantum Dots in TIPS-Tetracene Carboxylic Acid Ligands. J Phys Chem Lett 2018; 9:1454-1460. [PMID: 29506386 DOI: 10.1021/acs.jpclett.8b00099] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Singlet exciton fission allows for the generation of two triplet excitons for each photon absorbed within an organic semiconductor. Efficient harvesting of these triplets could allow for the Shockley-Queisser limit on the power conversion efficiency of single-junction photovoltaics to be broken. Here, we show that singlet fission molecules bound directly to PbS quantum dots as ligands can undergo singlet fission with near unity efficiency and can transfer triplets sequentially into the PbS with near unity efficiency. Within the PbS, the excitations recombine, giving rise of the emission of photons. This allows for the doubling of the quantum dot photoluminescence quantum efficiency when photons are absorbed by the singlet fission ligand, as compared to when directly absorbed in the quantum dot. Our approach demonstrates that it is possible to convert the exciton multiplication process of singlet fission into a photon multiplication process and provides a new path to harness singlet fission with photovoltaics.
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Affiliation(s)
- Nathaniel J L K Davis
- Cavendish Laboratory , University of Cambridge , J. J. Thomson Avenue , Cambridge , CB3 0HE , United Kingdom
| | - Jesse R Allardice
- Cavendish Laboratory , University of Cambridge , J. J. Thomson Avenue , Cambridge , CB3 0HE , United Kingdom
| | - James Xiao
- Cavendish Laboratory , University of Cambridge , J. J. Thomson Avenue , Cambridge , CB3 0HE , United Kingdom
| | - Anthony J Petty
- Department of Chemistry , University of Kentucky , 161 Jacobs Science Building , Lexington Kentucky 40506-0174 , United States
| | - Neil C Greenham
- Cavendish Laboratory , University of Cambridge , J. J. Thomson Avenue , Cambridge , CB3 0HE , United Kingdom
| | - John E Anthony
- Department of Chemistry , University of Kentucky , 161 Jacobs Science Building , Lexington Kentucky 40506-0174 , United States
| | - Akshay Rao
- Cavendish Laboratory , University of Cambridge , J. J. Thomson Avenue , Cambridge , CB3 0HE , United Kingdom
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171
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Broch K, Dieterle J, Branchi F, Hestand NJ, Olivier Y, Tamura H, Cruz C, Nichols VM, Hinderhofer A, Beljonne D, Spano FC, Cerullo G, Bardeen CJ, Schreiber F. Robust singlet fission in pentacene thin films with tuned charge transfer interactions. Nat Commun 2018; 9:954. [PMID: 29507287 PMCID: PMC5838205 DOI: 10.1038/s41467-018-03300-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 01/29/2018] [Indexed: 02/07/2023] Open
Abstract
Singlet fission, the spin-allowed photophysical process converting an excited singlet state into two triplet states, has attracted significant attention for device applications. Research so far has focused mainly on the understanding of singlet fission in pure materials, yet blends offer the promise of a controlled tuning of intermolecular interactions, impacting singlet fission efficiencies. Here we report a study of singlet fission in mixtures of pentacene with weakly interacting spacer molecules. Comparison of experimentally determined stationary optical properties and theoretical calculations indicates a reduction of charge-transfer interactions between pentacene molecules with increasing spacer molecule fraction. Theory predicts that the reduced interactions slow down singlet fission in these blends, but surprisingly we find that singlet fission occurs on a timescale comparable to that in pure crystalline pentacene. We explain the observed robustness of singlet fission in such mixed films by a mechanism of exciton diffusion to hot spots with closer intermolecular spacings.
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Affiliation(s)
- K Broch
- Institute of Applied Physics and Center for Light Matter Interactions, Sensors and Analytics, LISA+, University of Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany.
- Fritz-Haber Institute of the Max-Planck Society, Faradayweg 4-6, 14195, Berlin, Germany.
| | - J Dieterle
- Institute of Applied Physics and Center for Light Matter Interactions, Sensors and Analytics, LISA+, University of Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany
| | - F Branchi
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Milano, 20133, Italy
| | - N J Hestand
- Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
| | - Y Olivier
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000, Mons, Belgium
| | - H Tamura
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo, 113-8656, Japan
| | - C Cruz
- Department of Chemistry, University of California at Riverside, 501 Big Springs Rd, Riverside, CA, 92521, USA
| | - V M Nichols
- Department of Chemistry, University of California at Riverside, 501 Big Springs Rd, Riverside, CA, 92521, USA
| | - A Hinderhofer
- Institute of Applied Physics and Center for Light Matter Interactions, Sensors and Analytics, LISA+, University of Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany
| | - D Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000, Mons, Belgium
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
| | - F C Spano
- Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
| | - G Cerullo
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Milano, 20133, Italy
| | - C J Bardeen
- Department of Chemistry, University of California at Riverside, 501 Big Springs Rd, Riverside, CA, 92521, USA
| | - F Schreiber
- Institute of Applied Physics and Center for Light Matter Interactions, Sensors and Analytics, LISA+, University of Tübingen, Auf der Morgenstelle 10, 72076, Tübingen, Germany
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172
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Ito S, Nagami T, Nakano M. Molecular design for efficient singlet fission. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2018. [DOI: 10.1016/j.jphotochemrev.2018.01.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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173
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Japahuge A, Zeng T. Theoretical Studies of Singlet Fission: Searching for Materials and Exploring Mechanisms. Chempluschem 2018; 83:146-182. [PMID: 31957288 DOI: 10.1002/cplu.201700489] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 12/31/2017] [Indexed: 02/02/2023]
Abstract
In this Review article, a survey is given for theoretical studies in the subject of singlet fission. Singlet fission converts one singlet exciton to two triplet excitons. With the doubled number of excitons and the longer lifetime of the triplets, singlet fission provides an avenue to improve the photoelectric conversion efficiency in organic photovoltaic devices. It has been a subject of intense research in the past decade. Theoretical studies play an essential role in understanding singlet fission. This article presents a Review of theoretical studies in singlet fission since 2006, the year when the research interest in this subject was reignited. Both electronic structure and dynamics studies are covered. Electronic structure studies provide guidelines for designing singlet fission chromophores and insights into the couplings between single- and multi-excitonic states. The latter provides fundamental knowledge for engineering interchromophore conformations to enhance the fission efficiency. Dynamics studies reveal the importance of vibronic couplings in singlet fission.
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Affiliation(s)
- Achini Japahuge
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S5B6, Canada
| | - Tao Zeng
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S5B6, Canada
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174
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Dean JC, Zhang R, Hallani RK, Pensack RD, Sanders SN, Oblinsky DG, Parkin SR, Campos LM, Anthony JE, Scholes GD. Photophysical characterization and time-resolved spectroscopy of a anthradithiophene dimer: exploring the role of conformation in singlet fission. Phys Chem Chem Phys 2018; 19:23162-23175. [PMID: 28820218 DOI: 10.1039/c7cp03774k] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Quantitative singlet fission has been observed for a variety of acene derivatives such as tetracene and pentacene, and efforts to extend the library of singlet fission compounds is of current interest. Preliminary calculations suggest anthradithiophenes exhibit significant exothermicity between the first optically-allowed singlet state, S1, and 2 × T1 with an energy difference of >5000 cm-1. Given the fulfillment of this ingredient for singlet fission, here we investigate the singlet fission capability of a difluorinated anthradithiophene dimer (2ADT) covalently linked by a (dimethylsilyl)ethane bridge and derivatized by triisobutylsilylethynyl (TIBS) groups. Photophysical characterization of 2ADT and the single functionalized ADT monomer were carried out in toluene and acetone solution via absorption and fluorescence spectroscopy, and their photo-initiated dynamics were investigated with time-resolved fluorescence (TRF) and transient absorption (TA) spectroscopy. In accordance with computational predictions, two conformers of 2ADT were observed via fluorescence spectroscopy and were assigned to structures with the ADT cores trans or cis to one another about the covalent bridge. The two conformers exhibited markedly different excited state deactivation mechanisms, with the minor trans population being representative of the ADT monomer showing primarily radiative decay, while the dominant cis population underwent relaxation into an excimer geometry before internally converting to the ground state. The excimer formation kinetics were found to be solvent dependent, yielding time constants of ∼1.75 ns in toluene, and ∼600 ps in acetone. While the difference in rates elicits a role for the solvent in stabilizing the excimer structure, the rate is still decidedly long compared to most singlet fission rates of analogous dimers, suggesting that the excimer is neither a kinetic nor a thermodynamic trap, yet singlet fission was still not observed. The result highlights the sensitivity of the electronic coupling element between the singlet and correlated triplet pair states, to the dimer conformation in dictating singlet fission efficiency even when the energetic requirements are met.
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Affiliation(s)
- Jacob C Dean
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
| | - Ruomeng Zhang
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
| | - Rawad K Hallani
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Ryan D Pensack
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
| | - Samuel N Sanders
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Daniel G Oblinsky
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
| | - Sean R Parkin
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Luis M Campos
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - John E Anthony
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
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175
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Folie BD, Haber JB, Refaely-Abramson S, Neaton JB, Ginsberg NS. Long-Lived Correlated Triplet Pairs in a π-Stacked Crystalline Pentacene Derivative. J Am Chem Soc 2018; 140:2326-2335. [DOI: 10.1021/jacs.7b12662] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | - Jeffrey B. Neaton
- Kavli Energy NanoSciences Institute, Berkeley, California 94720, United States
| | - Naomi S. Ginsberg
- Kavli Energy NanoSciences Institute, Berkeley, California 94720, United States
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176
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Petti MK, Lomont JP, Maj M, Zanni MT. Two-Dimensional Spectroscopy Is Being Used to Address Core Scientific Questions in Biology and Materials Science. J Phys Chem B 2018; 122:1771-1780. [PMID: 29346730 DOI: 10.1021/acs.jpcb.7b11370] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two-dimensional spectroscopy is a powerful tool for extracting structural and dynamic information from a wide range of chemical systems. We provide a brief overview of the ways in which two-dimensional visible and infrared spectroscopies are being applied to elucidate fundamental details of important processes in biological and materials science. The topics covered include amyloid proteins, photosynthetic complexes, ion channels, photovoltaics, batteries, as well as a variety of promising new methods in two-dimensional spectroscopy.
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Affiliation(s)
- Megan K Petti
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Justin P Lomont
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Michał Maj
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Martin T Zanni
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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177
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Endothermic singlet fission is hindered by excimer formation. Nat Chem 2018; 10:305-310. [PMID: 29461531 DOI: 10.1038/nchem.2926] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 12/05/2017] [Indexed: 12/23/2022]
Abstract
Singlet fission is a process whereby two triplet excitons can be produced from one photon, potentially increasing the efficiency of photovoltaic devices. Endothermic singlet fission is desired for a maximum energy-conversion efficiency, and such systems have been considered to form an excimer-like state with multiexcitonic character prior to the appearance of triplets. However, the role of the excimer as an intermediate has, until now, been unclear. Here we show, using 5,12-bis((triisopropylsilyl)ethynyl)tetracene in solution as a prototypical example, that, rather than acting as an intermediate, the excimer serves to trap excited states to the detriment of singlet-fission yield. We clearly demonstrate that singlet fission and its conjugate process, triplet-triplet annihilation, occur at a longer intermolecular distance than an excimer intermediate would impute. These results establish that an endothermic singlet-fission material must be designed to avoid excimer formation, thus allowing singlet fission to reach its full potential in enhancing photovoltaic energy conversion.
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178
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Thampi A, Stern HL, Cheminal A, Tayebjee MJY, Petty AJ, Anthony JE, Rao A. Elucidation of Excitation Energy Dependent Correlated Triplet Pair Formation Pathways in an Endothermic Singlet Fission System. J Am Chem Soc 2018; 140:4613-4622. [PMID: 29275626 DOI: 10.1021/jacs.7b06274] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Singlet fission is the spin-allowed conversion of a photogenerated singlet exciton into two triplet excitons in organic semiconductors, which could enable single-junction photovoltaic cells to break the Shockley-Queisser limit. The conversion of singlets to free triplets is mediated by an intermediate correlated triplet pair (TT) state, but an understanding of how the formation and dissociation of these states depend on energetics and morphology is lacking. In this study, we probe the dynamics of TT states in a model endothermic fission system, TIPS-Tc nanoparticles, which show a mixture of crystalline and disordered regions. We observe the formation of different TT states, with varying yield and different rates of singlet decay, depending on the excitation energy. An emissive TT state is observed to grow in over 1 ns when excited at 480 nm, in contrast to excitation at lower energies where this emissive TT state is not observed. This suggests that the pathway for singlet fission in these nanoparticles is strongly influenced by the initial sub-100 fs relaxation of the photoexcited state away from the Franck-Condon point, with multiple possible TT states. On nanosecond time scales, the TT states are converted to free triplets, which suggests that TT states might diffuse into the disordered regions of the nanoparticles where their breakup to free triplets is favored. The free triplets then decay on μs time scales, despite the confined nature of the system. Our results provide important insights into the mechanism of endothermic singlet fission and the design of nanostructures to harness singlet fission.
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Affiliation(s)
- Arya Thampi
- Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , U.K
| | - Hannah L Stern
- Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , U.K
| | - Alexandre Cheminal
- Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , U.K
| | - Murad J Y Tayebjee
- Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , U.K
| | - Anthony J Petty
- University of Kentucky , Lexington , Kentucky 40506 , United States
| | - John E Anthony
- University of Kentucky , Lexington , Kentucky 40506 , United States
| | - Akshay Rao
- Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , U.K
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179
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Watanabe M, Miyazaki T, Matsushima T, Matsuda J, Chein CT, Shibahara M, Adachi C, Sun SS, Chow TJ, Ishihara T. Synthesis and physical properties of brominated hexacene and hole-transfer properties of thin-film transistors. RSC Adv 2018; 8:13259-13265. [PMID: 35542556 PMCID: PMC9079830 DOI: 10.1039/c7ra13632c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Accepted: 03/13/2018] [Indexed: 02/04/2023] Open
Abstract
A halide-substituted higher acene, 2-bromohexacene, and its precursor with a carbonyl bridge moiety were synthesized. The precursor was synthesized through 7 steps in a total yield of 2.5%. The structure of precursor and thermally converted 2-bromohexacene were characterized by solid state NMR, IR, and absorption spectra, as well as by DFT computation analysis. It exhibited high stability in the solid state over 3 months, therefore can be utilized in the fabrication of opto-electronic devices. The organic thin-film transistors (OFETs) were fabricated by using 2-bromohexacene and parent hexacene through vaccum deposition method. The best film mobility of 2-bromohexacene was observed at 0.83 cm2 V−1 s−1 with an on/off ratio of 5.0 × 104 and a threshold of −52 V, while the best film mobility of hexacene was observed at 0.076 cm2 V−1 s−1 with an on/off ratio of 2.4 × 102 and a threshold of −21 V. AFM measurement of 2-bromohexacene showed smooth film formation. The averaged mobility of 2-bromohexacene is 8 fold higher than the non-substituted hexacene. A halide-substituted higher acene, 2-bromohexacene, and its precursor with a carbonyl bridge moiety were synthesized.![]()
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Affiliation(s)
- Motonori Watanabe
- International Institute for Carbon Neutral Energy Research
- Kyushu University
- Fukuoka 819-0395
- Japan
| | - Takaaki Miyazaki
- Education Center for Global Leaders in Molecular Systems for Devices
- Kyushu University
- Fukuoka 819-0395
- Japan
| | - Toshinori Matsushima
- International Institute for Carbon Neutral Energy Research
- Kyushu University
- Fukuoka 819-0395
- Japan
- Center for Organic Photonics and Electronics Research (OPERA)
| | - Junko Matsuda
- International Institute for Carbon Neutral Energy Research
- Kyushu University
- Fukuoka 819-0395
- Japan
| | | | - Masahiko Shibahara
- Division of Natural Sciences
- Faculty of Science and Technology
- Oita University
- Oita
- Japan
| | - Chihaya Adachi
- International Institute for Carbon Neutral Energy Research
- Kyushu University
- Fukuoka 819-0395
- Japan
- Education Center for Global Leaders in Molecular Systems for Devices
| | | | - Tahsin J. Chow
- Institute of Chemistry
- Academia Sinica
- Taipei 11529
- Taiwan
- Department of Chemistry
| | - Tatsumi Ishihara
- International Institute for Carbon Neutral Energy Research
- Kyushu University
- Fukuoka 819-0395
- Japan
- Department of Applied Chemistry
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180
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Kato D, Sakai H, Araki Y, Wada T, Tkachenko NV, Hasobe T. Concentration-dependent photophysical switching in mixed self-assembled monolayers of pentacene and perylenediimide on gold nanoclusters. Phys Chem Chem Phys 2018. [DOI: 10.1039/c8cp00174j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The precise control and switching of photophysical processes such as singlet fission, electron transfer and excimer were performed using mixed SAMs of pentacene and perylenediimide units on Au nanoclusters.
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Affiliation(s)
- Daiki Kato
- Department of Chemistry
- Faculty of Science and Technology
- Keio University
- Kanagawa 223-8522
- Japan
| | - Hayato Sakai
- Department of Chemistry
- Faculty of Science and Technology
- Keio University
- Kanagawa 223-8522
- Japan
| | - Yasuyuki Araki
- Institute of Multidisciplinary Research for Advanced Materials
- Tohoku University
- Sendai 980-8577
- Japan
| | - Takehiko Wada
- Institute of Multidisciplinary Research for Advanced Materials
- Tohoku University
- Sendai 980-8577
- Japan
| | - Nikolai V. Tkachenko
- Laboratory of Chemistry and Bioengineering
- Tampere University of Technology
- 33101 Tampere
- Finland
| | - Taku Hasobe
- Department of Chemistry
- Faculty of Science and Technology
- Keio University
- Kanagawa 223-8522
- Japan
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181
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Refaely-Abramson S, da Jornada FH, Louie SG, Neaton JB. Origins of Singlet Fission in Solid Pentacene from an ab initio Green's Function Approach. PHYSICAL REVIEW LETTERS 2017; 119:267401. [PMID: 29328724 DOI: 10.1103/physrevlett.119.267401] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Indexed: 05/24/2023]
Abstract
We develop a new first-principles approach to predict and understand rates of singlet fission with an ab initio Green's-function formalism based on many-body perturbation theory. Starting with singlet and triplet excitons computed from a GW plus Bethe-Salpeter equation approach, we calculate the exciton-biexciton coupling to lowest order in the Coulomb interaction, assuming a final state consisting of two noninteracting spin-correlated triplets with finite center-of-mass momentum. For crystalline pentacene, symmetries dictate that the only purely Coulombic fission decay process from a bright singlet state requires a final state consisting of two inequivalent nearly degenerate triplets of nonzero, equal and opposite, center-of-mass momenta. For such a process, we predict a singlet lifetime of 30-70 fs, in very good agreement with experimental data, indicating that this process can dominate singlet fission in crystalline pentacene. Our approach is general and provides a framework for predicting and understanding multiexciton interactions in solids.
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Affiliation(s)
- Sivan Refaely-Abramson
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Felipe H da Jornada
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Steven G Louie
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jeffrey B Neaton
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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182
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Hart SM, Silva WR, Frontiera RR. Femtosecond stimulated Raman evidence for charge-transfer character in pentacene singlet fission. Chem Sci 2017; 9:1242-1250. [PMID: 29675170 PMCID: PMC5885776 DOI: 10.1039/c7sc03496b] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 12/12/2017] [Indexed: 12/22/2022] Open
Abstract
Evidence for transient anionic and cationic species in singlet fission is given by ultrafast Raman measurements.
Singlet fission is a spin-allowed process in which an excited singlet state evolves into two triplet states. We use femtosecond stimulated Raman spectroscopy, an ultrafast vibrational technique, to follow the molecular structural evolution during singlet fission in order to determine the mechanism of this process. In crystalline pentacene, we observe the formation of an intermediate characterized by pairs of excited state peaks that are red- and blue-shifted relative to the ground state features. We hypothesize that these features arise from the formation of cationic and anionic species due to partial transfer of electron density from one pentacene molecule to a neighboring molecule. These observations provide experimental evidence for the role of states with significant charge-transfer character which facilitate the singlet fission process in pentacene. Our work both provides new insight into the singlet fission mechanism in pentacene and demonstrates the utility of structurally-sensitive time-resolved spectroscopic techniques in monitoring ultrafast processes.
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Affiliation(s)
- Stephanie M Hart
- Department of Chemistry , University of Minnesota , Minneapolis , MN 55455 , USA .
| | - W Ruchira Silva
- Department of Chemistry , University of Minnesota , Minneapolis , MN 55455 , USA .
| | - Renee R Frontiera
- Department of Chemistry , University of Minnesota , Minneapolis , MN 55455 , USA .
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183
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Sun KW, Yao Y. Beating maps of singlet fission: Simulation of coherent two-dimensional electronic spectroscopy by Davydov ansatz in organic molecules. J Chem Phys 2017; 147:224905. [DOI: 10.1063/1.5005564] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Ke-Wei Sun
- School of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Yao Yao
- Department of Physics, South China University of Technology, Guangzhou 510640, China
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184
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Grieco C, Kennehan ER, Rimshaw A, Payne MM, Anthony JE, Asbury JB. Harnessing Molecular Vibrations to Probe Triplet Dynamics During Singlet Fission. J Phys Chem Lett 2017; 8:5700-5706. [PMID: 29112418 DOI: 10.1021/acs.jpclett.7b02434] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Ultrafast vibrational spectroscopy in the mid-infrared spectral range provides the opportunity to probe the dynamics of electronic states involved in all stages of the singlet fission reaction through their unique vibrational frequencies. This capability is demonstrated using a model singlet fission chromophore, 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn). The alkyne groups of the TIPS side chains are coupled to the conjugated framework of the pentacene cores, enabling direct examination of the dynamics of triplet excitons that have successfully separated from correlated triplet pair states in crystalline films of TIPS-Pn. Relaxation processes during the separation of triplet excitons and triplet-triplet annihilation after their separation result in the formation of hot ground state molecules that also exhibit unique vibrational frequencies. Because all organic molecules possess native vibrational modes, ultrafast vibrational spectroscopy offers a new approach to examine the dynamics of electronic intermediates that may inform ongoing efforts to utilize singlet fission to overcome thermalization losses in photovoltaic applications.
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Affiliation(s)
- Christopher Grieco
- Department of Chemistry, The Pennsylvania State University , State College, Pennsylvania 16801, United States
| | - Eric R Kennehan
- Department of Chemistry, The Pennsylvania State University , State College, Pennsylvania 16801, United States
| | - Adam Rimshaw
- Department of Chemistry, The Pennsylvania State University , State College, Pennsylvania 16801, United States
| | - Marcia M Payne
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, 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 , State College, Pennsylvania 16801, United States
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185
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Bera K, Douglas CJ, Frontiera RR. Femtosecond Raman Microscopy Reveals Structural Dynamics Leading to Triplet Separation in Rubrene Singlet Fission. J Phys Chem Lett 2017; 8:5929-5934. [PMID: 29166019 DOI: 10.1021/acs.jpclett.7b02769] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Singlet fission generates multiple excitons from a single photon, which in theory can result in solar cell efficiencies with values above the Shockley-Queisser limit. Understanding the molecular structural dynamics during singlet fission will help to fabricate efficient organic photovoltaic devices. Here we use femtosecond stimulated Raman spectroscopy to reveal the structural evolution during the triplet separation in rubrene. We observe vibrational signatures of the correlated triplet pair, as well as shifting of the vibrational frequencies of the 1430 and 1542 cm-1 excited state modes, which increase by more than 25 cm-1 in 5 ps. Our results indicate that the correlated pair separation into two individual triplets occurs concurrently with the loss of electron density from the tetracene backbone in rubrene. This study provides new insights into the triplet separation process and proves the utility of structurally sensitive ultrafast vibrational techniques to understand the mechanism of singlet fission.
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Affiliation(s)
- Kajari Bera
- Department of Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Christopher J Douglas
- Department of Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
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186
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Abraham V, Mayhall NJ. Simple Rule To Predict Boundedness of Multiexciton States in Covalently Linked Singlet-Fission Dimers. J Phys Chem Lett 2017; 8:5472-5478. [PMID: 29061043 DOI: 10.1021/acs.jpclett.7b02476] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Because of the potential for increasing solar cell efficiencies, significant effort has been spent understanding the mechanism of singlet fission. We provide a simple connectivity rule to predict whether the through-bond coupling will be stabilizing or destabilizing for the 1(TT) state in covalently linked singlet-fission chromophores. By drawing an analogy between the chemical system and a simple spin-lattice, one is able to determine the ordering of the multiexciton spin state via a generalized usage of Ovchinnikov's rule. This allows one to predict (without any computation) whether the 1(TT) multiexciton state will be bound or unbound with respect to the separated triplets in covalently linked singlet-fission dimers. To test our hypothesis, we have performed ab initio calculations on a systematic series of covalently linked singlet-fission dimers. Numerical examples are given, and the limitations of the proposed theory are explored.
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Affiliation(s)
- Vibin Abraham
- Department of Chemistry, Virginia Tech , Blacksburg, Virginia 24060, United States
| | - Nicholas J Mayhall
- Department of Chemistry, Virginia Tech , Blacksburg, Virginia 24060, United States
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187
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Pun AB, Sanders SN, Kumarasamy E, Sfeir MY, Congreve DN, Campos LM. Triplet Harvesting from Intramolecular Singlet Fission in Polytetracene. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1701416. [PMID: 28910503 DOI: 10.1002/adma.201701416] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 06/30/2017] [Indexed: 06/07/2023]
Abstract
Singlet fission (SF), a promising mechanism of multiple exciton generation, has only recently been engineered as a fast, efficient, intramolecular process (iSF). The challenge now lies in designing and optimizing iSF materials that can be practically applied in high-performance optoelectronic devices. However, most of the reported iSF systems, such as those based on donor-acceptor polymers or pentacene, have low triplet energies, which limits their applications. Tetracene-based materials can overcome significant challenges, as the tetracene triplet state is practically useful, ≈1.2 eV. Here, the synthesis and excited state dynamics of a conjugated tetracene homopolymer are studied. This polymer undergoes ultrafast iSF in solution, generating high-energy triplets on a sub-picosecond time scale. Magnetic-field-dependent photocurrent measurements of polytetracene-based devices demonstrate the first example of iSF-generated triplet extraction in devices, exhibiting the potential of iSF materials for use in next-generation devices.
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Affiliation(s)
- 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
| | - Daniel N Congreve
- Energy Frontier Research Center for Excitonics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Luis M Campos
- Department of Chemistry, Columbia University, New York, NY, 10027, USA
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188
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Buchanan EA, Michl J. Packing Guidelines for Optimizing Singlet Fission Matrix Elements in Noncovalent Dimers. J Am Chem Soc 2017; 139:15572-15575. [DOI: 10.1021/jacs.7b07963] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Eric A. Buchanan
- Department
of Chemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Josef Michl
- Department
of Chemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo
nám. 2, 16610 Prague 6, Czech Republic
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189
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Berkelbach TC. Electronic Structure and Dynamics of Singlet Fission in Organic Molecules and Crystals. ADVANCES IN CHEMICAL PHYSICS 2017. [DOI: 10.1002/9781119324560.ch1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Affiliation(s)
- Timothy C. Berkelbach
- Department of Chemistry and The James Franck Institute; The University of Chicago; Chicago IL 60637 USA
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190
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Zang H, Zhao Y, Liang W. Quantum Interference in Singlet Fission: J- and H-Aggregate Behavior. J Phys Chem Lett 2017; 8:5105-5112. [PMID: 28960999 DOI: 10.1021/acs.jpclett.7b01996] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The quantum interference in singlet fission (SF) among the multiple pathways from singlet excited states to correlated triplet pair states is comprehensively investigated. The analytical analysis reveals that this interference is strongly affected by the exciton-exciton coupling and is closely related to the property of J- and H-type of aggregates. Different from the interference in the spectra of aggregates, which depends only on the sign of exciton-exciton coupling, the interference in SF is additionally related to the signs of couplings between singlet excited states and triplet pair states. The interference dynamics is further demonstrated numerically by a time-dependent wavepacket diffusion method with electron-phonon interactions incorporated. Finally, we take a pentacene dimer as a concrete example to show how to adjust the constructive and destructive interferences in SF dynamics in terms of J-/H-aggregate behaviors. The results presented here may provide guiding principles for designing efficient SF materials through directly tuning quantum interference via morphology engineering.
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Affiliation(s)
- Hang Zang
- Department of Chemical Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Yi Zhao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen, Fujian 361005, China
| | - WanZhen Liang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen, Fujian 361005, China
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191
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Mauck CM, Bae YJ, Chen M, Powers‐Riggs N, Wu Y, Wasielewski MR. Charge‐Transfer Character in a Covalent Diketopyrrolopyrrole Dimer: Implications for Singlet Fission. CHEMPHOTOCHEM 2017. [DOI: 10.1002/cptc.201700135] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Catherine M. Mauck
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, Institute for Sustainability and Energy at Northwestern Northwestern University Evanston IL 60208-3113 USA
| | - Youn Jue Bae
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, Institute for Sustainability and Energy at Northwestern Northwestern University Evanston IL 60208-3113 USA
| | - Michelle Chen
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, Institute for Sustainability and Energy at Northwestern Northwestern University Evanston IL 60208-3113 USA
| | - Natalia Powers‐Riggs
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, Institute for Sustainability and Energy at Northwestern Northwestern University Evanston IL 60208-3113 USA
| | - Yi‐Lin Wu
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, Institute for Sustainability and Energy at Northwestern Northwestern University Evanston IL 60208-3113 USA
| | - Michael R. Wasielewski
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, Institute for Sustainability and Energy at Northwestern Northwestern University Evanston IL 60208-3113 USA
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192
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Bai S, Barbatti M. Divide-to-Conquer: A Kinetic Model for Singlet Oxygen Photosensitization. J Chem Theory Comput 2017; 13:5528-5538. [DOI: 10.1021/acs.jctc.7b00619] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shuming Bai
- Aix Marseille Univ, CNRS, ICR, 13397 Marseille, France
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193
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Khan S, Mazumdar S. Diagrammatic Exciton Basis Theory of the Photophysics of Pentacene Dimers. J Phys Chem Lett 2017; 8:4468-4478. [PMID: 28853895 DOI: 10.1021/acs.jpclett.7b01829] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Covalently linked acene dimers are of interest as candidates for intramolecular singlet fission. We report many-electron calculations of the energies and wave functions of the optical singlets, the lowest triplet exciton, and the triplet-triplet biexciton, as well as the final states of excited state absorptions from these states in a family of phenyl-linked pentacene dimers. While it is difficult to distinguish the triplet and the triplet-triplet from their transient absorptions in the 500-600 nm region, by comparing theoretical transient absorption spectra against earlier and very recent experimental transient absorptions in the near- and mid-infrared, we conclude that the end product of photoexcitation in these particular bipentacenes is the bound triplet-triplet and not free triplets. We predict additional transient absorptions at even longer wavelengths, beyond 1500 nm, to the equivalent of the classic 21Ag- in linear polyenes.
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Affiliation(s)
- Souratosh Khan
- Department of Physics, ‡Department of Chemistry and Biochemistry, and §College of Optical Sciences, University of Arizona , Tucson, Arizona 85721, United States
| | - Sumit Mazumdar
- Department of Physics, ‡Department of Chemistry and Biochemistry, and §College of Optical Sciences, University of Arizona , Tucson, Arizona 85721, United States
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194
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Vibronically coherent ultrafast triplet-pair formation and subsequent thermally activated dissociation control efficient endothermic singlet fission. Nat Chem 2017; 9:1205-1212. [PMID: 29168494 DOI: 10.1038/nchem.2856] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 07/28/2017] [Indexed: 12/20/2022]
Abstract
Singlet exciton fission (SF), the conversion of one spin-singlet exciton (S1) into two spin-triplet excitons (T1), could provide a means to overcome the Shockley-Queisser limit in photovoltaics. SF as measured by the decay of S1 has been shown to occur efficiently and independently of temperature, even when the energy of S1 is as much as 200 meV less than that of 2T1. Here we study films of triisopropylsilyltetracene using transient optical spectroscopy and show that the triplet pair state (TT), which has been proposed to mediate singlet fission, forms on ultrafast timescales (in 300 fs) and that its formation is mediated by the strong coupling of electronic and vibrational degrees of freedom. This is followed by a slower loss of singlet character as the excitation evolves to become only TT. We observe the TT to be thermally dissociated on 10-100 ns timescales to form free triplets. This provides a model for 'temperature-independent' efficient TT formation and thermally activated TT separation.
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195
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Kumarasamy E, Sanders SN, Tayebjee MJY, Asadpoordarvish A, Hele TJH, Fuemmeler EG, Pun AB, Yablon LM, Low JZ, Paley DW, Dean JC, Choi B, Scholes GD, Steigerwald ML, Ananth N, McCamey DR, Sfeir MY, Campos LM. Tuning Singlet Fission in π-Bridge-π Chromophores. J Am Chem Soc 2017; 139:12488-12494. [PMID: 28799752 DOI: 10.1021/jacs.7b05204] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We have designed a series of pentacene dimers separated by homoconjugated or nonconjugated bridges that exhibit fast and efficient intramolecular singlet exciton fission (iSF). These materials are distinctive among reported iSF compounds because they exist in the unexplored regime of close spatial proximity but weak electronic coupling between the singlet exciton and triplet pair states. Using transient absorption spectroscopy to investigate photophysics in these molecules, we find that homoconjugated dimers display desirable excited-state dynamics, with significantly reduced recombination rates as compared to conjugated dimers with similar singlet fission rates. In addition, unlike conjugated dimers, the time constants for singlet fission are relatively insensitive to the interplanar angle between chromophores, since rotation about σ bonds negligibly affects the orbital overlap within the π-bonding network. In the nonconjugated dimer, where the iSF occurs with a time constant >10 ns, comparable to the fluorescence lifetime, we used electron spin resonance spectroscopy to unequivocally establish the formation of triplet-triplet multiexcitons and uncoupled triplet excitons through singlet fission. Together, these studies enable us to articulate the role of the conjugation motif in iSF.
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Affiliation(s)
| | | | - Murad J Y Tayebjee
- Cavendish Laboratory, University of Cambridge , J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | | | - Timothy J H Hele
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14850, United States.,Jesus College, Cambridge University , Cambridge CB5 8BL, United Kingdom
| | - Eric G Fuemmeler
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14850, United States
| | | | | | | | | | - Jacob C Dean
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | | | - Gregory D Scholes
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | | | - Nandini Ananth
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14850, United States
| | | | - Matthew Y Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
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196
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Nagami T, Ito S, Kubo T, Nakano M. Intermolecular Packing Effects on Singlet Fission in Oligorylene Dimers. ACS OMEGA 2017; 2:5095-5103. [PMID: 30023738 PMCID: PMC6044983 DOI: 10.1021/acsomega.7b00655] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 08/14/2017] [Indexed: 06/08/2023]
Abstract
Using the density functional theory method, the crystalline packing effect on the singlet fission (SF) rate of oligorylenes, some of which are found to exhibit SF in crystal forms, is revealed by evaluating the effective electronic coupling (|Veff|), the square of which is proportional to the SF rate. The |Veff| values for terrylene and quaterrylene dimer models are investigated for a variety of slip-stacked forms. It is found that these values show similar dependences on the intermolecular packing as a function of lateral and longitudinal displacements of monomer frameworks, and that they are maximized in several configurations of one monomer slipped from another along the longitudinal axis. The present estimation method of the SF rate is also found to qualitatively explain the experimental SF rate difference between terrylene derivatives with different packing forms. Furthermore, by analyzing the effect of electronic couplings on the adiabatic electronic states related to SF, we predict several favorable molecular packings leading to a fast SF with a high triplet yield.
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Affiliation(s)
- Takanori Nagami
- Department
of Materials Engineering Science, Graduate School of Engineering
Science and Center for Spintronics Research Network (CSRN), Graduate School of
Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Soichi Ito
- Department
of Materials Engineering Science, Graduate School of Engineering
Science and Center for Spintronics Research Network (CSRN), Graduate School of
Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Takashi Kubo
- Department
of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Masayoshi Nakano
- Department
of Materials Engineering Science, Graduate School of Engineering
Science and Center for Spintronics Research Network (CSRN), Graduate School of
Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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197
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Nienhaus L, Wu M, Geva N, Shepherd JJ, Wilson MWB, Bulović V, Van Voorhis T, Baldo MA, Bawendi MG. Speed Limit for Triplet-Exciton Transfer in Solid-State PbS Nanocrystal-Sensitized Photon Upconversion. ACS NANO 2017; 11:7848-7857. [PMID: 28745512 DOI: 10.1021/acsnano.7b02024] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Hybrid interfaces combining inorganic and organic materials underpin the operation of many optoelectronic and photocatalytic systems and allow for innovative approaches to photon up- and down-conversion. However, the mechanism of exchange-mediated energy transfer of spin-triplet excitons across these interfaces remains obscure, particularly when both the macroscopic donor and acceptor are composed of many separately interacting nanoscopic moieties. Here, we study the transfer of excitons from colloidal lead sulfide (PbS) nanocrystals to the spin-triplet state of rubrene molecules. By reducing the length of the carboxylic acid ligands on the nanocrystal surface from 18 to 4 carbon atoms, thinning the effective ligand shell from 13 to 6 Å, we are able to increase the characteristic transfer rate by an order of magnitude. However, we observe that the energy transfer rate asymptotes for shorter separation distances (≤10 Å) which we attribute to the reduced Dexter coupling brought on by the increased effective dielectric constant of these solid-state devices when the aliphatic ligands are short. This implies that the shortest ligands, which hinder long-term colloidal stability, offer little advantage for energy transfer. Indeed, we find that hexanoic acid ligands are already sufficient for near-unity transfer efficiency. Using nanocrystals with these optimal-length ligands in an improved solid-state device structure, we obtain an upconversion efficiency of (7 ± 1)% with excitation at λ = 808 nm.
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Affiliation(s)
- Lea Nienhaus
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Mengfei Wu
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Nadav Geva
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - James J Shepherd
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Mark W B Wilson
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Vladimir Bulović
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Troy Van Voorhis
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Marc A Baldo
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Moungi G Bawendi
- Department of Chemistry, ‡Department of Electrical Engineering and Computer Science, and §Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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198
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Breen I, Tempelaar R, Bizimana LA, Kloss B, Reichman DR, Turner DB. Triplet Separation Drives Singlet Fission after Femtosecond Correlated Triplet Pair Production in Rubrene. J Am Chem Soc 2017; 139:11745-11751. [PMID: 28763611 DOI: 10.1021/jacs.7b02621] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Singlet fission, a multistep molecular process in which one photon generates two triplet excitons, holds great technological promise. Here, by applying a combination of transient transmittance and two-dimensional electronic spectroscopy with 5 fs laser pulses, we resolve the full set of fission steps before the onset of spin dephasing. In addition to its role as a viable singlet fission material, single-crystalline rubrene is selected because its energetics and transition dipole alignment uniquely allow for the unambiguous identification of the various fission steps through their contributions to distinct spectroscopic features. The measurements reveal that the neighboring correlated triplet pair achieves its maximum population within 20 fs. Subsequent growth of the triplet signal on picosecond time scales is attributable to spatial separation of the triplets, proceeding nonadiabatically through weakly coupled but near-resonant states. As such, we provide evidence in crystalline rubrene for a singlet fission step that, until now, has not been convincingly observed.
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Affiliation(s)
- Ilana Breen
- Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States
| | - Roel Tempelaar
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
| | - Laurie A Bizimana
- Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States
| | - Benedikt Kloss
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
| | - David R Reichman
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
| | - Daniel B Turner
- Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States
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199
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Minaki H, Kawata S, Furudate J, Saito A, Katagiri H, Pu YJ. Donor- or Acceptor-type 9,9′-Bifluorenylidene Derivatives for Attaining Singlet Fission Character in Organic Photovoltaics. CHEM LETT 2017. [DOI: 10.1246/cl.170437] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hiroko Minaki
- Graduate School of Organic Materials Science, Yamagata University, Yonezawa, Yamagata 992-8510
| | - So Kawata
- Graduate School of Organic Materials Science, Yamagata University, Yonezawa, Yamagata 992-8510
| | - Junki Furudate
- Graduate School of Organic Materials Science, Yamagata University, Yonezawa, Yamagata 992-8510
| | - Ayaka Saito
- Graduate School of Organic Materials Science, Yamagata University, Yonezawa, Yamagata 992-8510
| | - Hiroshi Katagiri
- Graduate School of Organic Materials Science, Yamagata University, Yonezawa, Yamagata 992-8510
| | - Yong-Jin Pu
- Graduate School of Organic Materials Science, Yamagata University, Yonezawa, Yamagata 992-8510
- JST-PRESTO, Kawaguchi, Saitama 332-0012
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Huang Z, Fujihashi Y, Zhao Y. Effect of Off-Diagonal Exciton-Phonon Coupling on Intramolecular Singlet Fission. J Phys Chem Lett 2017; 8:3306-3312. [PMID: 28673087 DOI: 10.1021/acs.jpclett.7b01247] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Intramolecular singlet fission (iSF) materials provide remarkable advantages in terms of tunable electronic structures, and quantum chemistry studies have indicated strong electronic coupling modulation by high frequency phonon modes. In this work, we formulate a microscopic model of iSF with simultaneous diagonal and off-diagonal coupling to high-frequency modes. A nonperturbative treatment, the Dirac-Frenkel time-dependent variational approach is adopted using the multiple Davydov trial states. It is shown that both diagonal and off-diagonal coupling can aid efficient singlet fission if excitonic coupling is weak, and fission is only facilitated by diagonal coupling if excitonic coupling is strong. In the presence of off-diagonal coupling, it is found that high frequency modes create additional fission channels for rapid iSF. Results presented here may help provide guiding principles for design of efficient singlet fission materials by directly tuning singlet-triplet interstate coupling.
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Affiliation(s)
- Zhongkai Huang
- Division of Materials Science, Nanyang Technological University , Singapore 639798, Singapore
| | - Yuta Fujihashi
- 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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