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Wang K, You X, Miao X, Yi Y, Peng S, Wu D, Chen X, Xu J, Sfeir MY, Xia J. Activated Singlet Fission Dictated by Anti-Kasha Property in a Rylene Imide Dye. J Am Chem Soc 2024; 146:13326-13335. [PMID: 38693621 DOI: 10.1021/jacs.4c01732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
A key challenge in the search of new materials capable of singlet fission (SF) arises from the primary energy conservation criterion, i.e., the energy of the triplet exciton has to be half that of the singlet (E(S1) ≥ 2E(T1)), which excludes most photostable organic materials from consideration and confines the design strategy to materials with low energy triplet states. One potential way to overcome this energy requirement and improve the triplet energy is to enable a SF channel from higher energy ("hot") excitonic states (Sn) in a process called activated SF. Herein, we demonstrate that efficient activated SF is achieved in a rylene imide-based derivative acenaphth[l, 2-a]acenaphthylene diimide (AADI). This process is enabled by an increase in the energy gap to greater than 1.0 eV between the S3 and S1 states due to the incorporation of an antiaromatic pentalene unit, which leads to the emergence of anti-Kasha properties in the isolated molecule. Transient spectroscopy studies show that AADI undergoes ultrafast SF from higher singlet excited states in thin film, with excitation wavelength-dependent SF yields. The SF yield of ∼200% is observed upon higher energy excitation, and long-lived free triplets persist on the μs time scale suggesting that AADI can be used in SF-enhanced devices. Our results suggest that enlarging the Sn-S1 energy gap is an effective way to turn on the activated SF channel and shed light on the development of novel, stable SF materials with high triplet energies.
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Affiliation(s)
- Kangwei Wang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Xiaoxiao You
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Xiaodan Miao
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy Sciences, Beijing 100049, China
| | - Yuanping Yi
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy Sciences, Beijing 100049, China
| | - Shaoqian Peng
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Di Wu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Xingyu Chen
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Jingwen Xu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Matthew Y Sfeir
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York 10016, United States
- Department of Physics, Graduate Center, City University of New York, New York 10031, United States
| | - Jianlong Xia
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
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2
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Vong D, Maleki F, Novak EC, Daemen LL, Moulé AJ. Measuring Intermolecular Excited State Geometry for Favorable Singlet Fission in Tetracene. J Phys Chem Lett 2024; 15:1188-1194. [PMID: 38270396 DOI: 10.1021/acs.jpclett.3c02343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
Singlet fission (SF) is the process of converting an excited singlet to a pair of excited triplets. Harvesting two charges from a single photon has the potential to increase photovoltaic device efficiencies. Acenes, such as tetracene and pentacene, are model molecules for studying SF. Despite SF being an endoergic process for tetracene and exoergic for pentacene, both acenes exhibit near unity SF quantum efficiencies, raising questions about how tetracene can overcome the energy barrier. Here, we use recently developed instrumentation to measure inelastic neutron scattering (INS) while optically exciting the model molecules using two different excitation energies. The spectroscopic results reveal intermolecular structural relaxation due to the presence of a triplet excited state. The structural dynamics of the combined excited state molecule and surrounding tetracene molecules are further studied using time-dependent density functional theory (TD-DFT), which shows that the singlet and triplet levels shift due to the excited state geometry, reducing the uphill energy barrier for SF to within kT.
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Affiliation(s)
- Daniel Vong
- Department of Materials Science and Engineering, University of California Davis, Davis, California 95616, United States
| | - Farahnaz Maleki
- Department of Chemical Engineering, University of California Davis, Davis, California 95616, United States
| | - Eric C Novak
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Luke L Daemen
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Adam J Moulé
- Department of Chemical Engineering, University of California Davis, Davis, California 95616, United States
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3
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Dong S, Yang B, Xin Q, Lan X, Wang X, Xin G. Interfacial thermal transport of graphene/β-Ga 2O 3 heterojunctions: a molecular dynamics study with a self-consistent interatomic potential. Phys Chem Chem Phys 2022; 24:12837-12848. [PMID: 35475984 DOI: 10.1039/d1cp05749a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Graphene/β-Ga2O3 heterojunctions are widely used in high-power and high-frequency devices, for which thermal management is vital to the device operation and life. Here we apply molecular dynamics simulation to calculate the interfacial thermal resistance (ITR) between graphene and β-Ga2O3. Based on the rigid ion model, a self-consistent interatomic potential with a set of parameters that can well reproduce the basic physical properties of crystal β-Ga2O3 is fitted. Using this potential, the effects of model size, interface type, temperature, vacancy defects and graphene hydrogenation on the ITR of graphene/β-Ga2O3 heterojunctions are evaluated. The results show that there is no obvious dependence of ITR on the size of graphene and β-Ga2O3. It is reported that the ITR values of the (100), (010) and (001) interfaces are 7.28 ± 0.35 × 10-8 K m2 W-1, 6.69 ± 0.44 × 10-8 K m2 W-1 and 5.22 ± 0.35 × 10-8 K m2 W-1 at 300 K, respectively. Both temperature increase and vacancy defect increase can prompt the energy propagation across graphene/β-Ga2O3 interfaces due to the enhancement of phonon coupling. In addition, graphene hydrogenation provides new channels for in-plane and out-of-plane phonon coupling, and thus reduces the ITR between graphene and β-Ga2O3. This study provides basic strategies for the thermal design and management of graphene/β-Ga2O3 based photoelectric devices.
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Affiliation(s)
- Shilin Dong
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China.
| | - Bowen Yang
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China.
| | - Qian Xin
- Shandong Technology Center of Nanodevices and Integration, School of Microelectronics, Shandong University, Jinan 250100, China
| | - Xin Lan
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China.
| | - Xinyu Wang
- Institute of Thermal Science and Technology, Shandong University, Jinan 250061, China
| | - Gongming Xin
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China.
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4
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Ye L, Liu Y, Zhou Q, Tao W, Li Y, Wang Z, Zhu H. Ultrafast Singlet Energy Transfer before Fission in a Tetracene/WSe 2 Type II Hybrid Heterostructure. J Phys Chem Lett 2021; 12:8440-8446. [PMID: 34436908 DOI: 10.1021/acs.jpclett.1c02540] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Hybrid heterostructures comprising organic and two-dimensional (2D) layered semiconductors hold great promise for light harvesting and optoelectronic applications. Among them, organic materials that exhibit singlet fission (SF) in which one singlet exciton generates two triplet excitons are particularly attractive and can potentially improve the performance of the device. However, SF-enhanced devices require that SF can compete with direct energy/charge transfer from the singlet exciton. Here, we performed ultrafast spectroscopic studies on a prototypical heterostructure consisting of tetracene (Tc) and monolayer WSe2. We show a type II band alignment with 16.5 ps hole transfer from photoexcited WSe2 to tetracene and a long-lived (∼565 ps) charge separation. Importantly, we show ultrafast (∼3.4 ps) singlet exciton energy transfer from photoexcited tetracene to WSe2, prior to the slow SF process (>20 ps) in tetracene. This study raises the challenge and calls for the careful design of SF-enhanced 2D optoelectronic devices.
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Affiliation(s)
- Lei Ye
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Yanping Liu
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Qiaohui Zhou
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Weijian Tao
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Yujie Li
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Zukun Wang
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Haiming Zhu
- State Key Laboratory of Modern Optical Instrumentation, Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
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5
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Seiler H, Krynski M, Zahn D, Hammer S, Windsor YW, Vasileiadis T, Pflaum J, Ernstorfer R, Rossi M, Schwoerer H. Nuclear dynamics of singlet exciton fission in pentacene single crystals. SCIENCE ADVANCES 2021; 7:7/26/eabg0869. [PMID: 34172443 PMCID: PMC8232917 DOI: 10.1126/sciadv.abg0869] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/14/2021] [Indexed: 05/22/2023]
Abstract
Singlet exciton fission (SEF) is a key process for developing efficient optoelectronic devices. An aspect rarely probed directly, yet with tremendous impact on SEF properties, is the nuclear structure and dynamics involved in this process. Here, we directly observe the nuclear dynamics accompanying the SEF process in single crystal pentacene using femtosecond electron diffraction. The data reveal coherent atomic motions at 1 THz, incoherent motions, and an anisotropic lattice distortion representing the polaronic character of the triplet excitons. Combining molecular dynamics simulations, time-dependent density-functional theory, and experimental structure factor analysis, the coherent motions are identified as collective sliding motions of the pentacene molecules along their long axis. Such motions modify the excitonic coupling between adjacent molecules. Our findings reveal that long-range motions play a decisive part in the electronic decoupling of the electronically correlated triplet pairs and shed light on why SEF occurs on ultrafast time scales.
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Affiliation(s)
- Hélène Seiler
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany.
| | - Marcin Krynski
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany
| | - Daniela Zahn
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany
| | - Sebastian Hammer
- Julius-Maximilians-Universität, Experimentelle Physik VI, Am Hubland, 97074 Würzburg, Germany.
| | | | | | - Jens Pflaum
- Julius-Maximilians-Universität, Experimentelle Physik VI, Am Hubland, 97074 Würzburg, Germany
- Bayerisches Zentrum für Angewandte Energieforschung, Magdalene-Schoch-Straße 3, 97074 Würzburg, Germany
| | - Ralph Ernstorfer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany
| | - Mariana Rossi
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany.
- Max-Planck-Institut für Struktur und Dynamik der Materie, 22761 Hamburg, Germany
| | - Heinrich Schwoerer
- Max-Planck-Institut für Struktur und Dynamik der Materie, 22761 Hamburg, Germany.
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6
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Manna B, Nandi A. Singlet fission in nanoaggregate of bis(phenylethynyl) derivative of benzene (BPEB): High energy triplet exciton generation with >100 % yield. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2021.113251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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7
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Speelman T, Cunha AV, Kathir RK, Havenith RWA. Electronic couplings for singlet fission: Orbital choice and extrapolation to the complete basis set limit. J Comput Chem 2021; 42:326-333. [PMID: 33616968 PMCID: PMC7898305 DOI: 10.1002/jcc.26458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 11/05/2022]
Abstract
For the search for promising singlet fission candidates, the calculation of the effective electronic coupling, which is required to estimate the singlet fission rate between the initially excited state (S0S1) and the multiexcitonic state (1TT, two triplets on neighboring molecules, coupled into a singlet), should be sufficiently reliable and fast enough to explore the configuration space. We propose here to modify the calculation of the effective electronic coupling using a nonorthogonal configuration interaction approach by: (a) using only one set of orbitals, optimized for the triplet state of the molecules, to describe all molecular electronic states, and (b) only taking the leading configurations into consideration. Furthermore, we also studied the basis set convergence of the electronic coupling, and we found, by comparison to the complete basis set limit obtained using the cc-pVnZ series of basis sets, that both the aug-cc-pVDZ and 6-311++G** basis sets are a good compromise between accuracy and computational feasibility. The proposed approach enables future work on larger clusters of molecules than dimers.
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Affiliation(s)
- Tom Speelman
- Stratingh Institute for ChemistryUniversity of GroningenGroningenThe Netherlands
| | - Ana V. Cunha
- High Performance Computing GroupSURFSaraAmsterdamThe Netherlands
| | - R. K. Kathir
- Zernike Institute for Advanced MaterialsUniversity of GroningenGroningenThe Netherlands
| | - Remco W. A. Havenith
- Stratingh Institute for ChemistryUniversity of GroningenGroningenThe Netherlands
- Zernike Institute for Advanced MaterialsUniversity of GroningenGroningenThe Netherlands
- Department of Inorganic and Physical ChemistryGhent UniversityGhentBelgium
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8
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Cainelli M, Tanimura Y. Exciton transfer in organic photovoltaic cells: A role of local and nonlocal electron–phonon interactions in a donor domain. J Chem Phys 2021; 154:034107. [DOI: 10.1063/5.0036590] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mauro Cainelli
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshitaka Tanimura
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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9
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Cruz CD, Chronister EL, Bardeen CJ. Using temperature dependent fluorescence to evaluate singlet fission pathways in tetracene single crystals. J Chem Phys 2020; 153:234504. [PMID: 33353314 DOI: 10.1063/5.0031458] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The temperature-dependent fluorescence spectrum, decay rate, and spin quantum beats are examined in single tetracene crystals to gain insight into the mechanism of singlet fission. Over the temperature range of 250 K-500 K, the vibronic lineshape of the emission indicates that the singlet exciton becomes localized at 400 K. The fission process is insensitive to this localization and exhibits Arrhenius behavior with an activation energy of 550 ± 50 cm-1. The damping rate of the triplet pair spin quantum beats in the delayed fluorescence also exhibits an Arrhenius temperature dependence with an activation energy of 165 ± 70 cm-1. All the data for T > 250 K are consistent with direct production of a spatially separated 1(T⋯T) state via a thermally activated process, analogous to spontaneous parametric downconversion of photons. For temperatures in the range of 20 K-250 K, the singlet exciton continues to undergo a rapid decay on the order of 200 ps, leaving a red-shifted emission that decays on the order of 100 ns. At very long times (≈1 µs), a delayed fluorescence component corresponding to the original S1 state can still be resolved, unlike in polycrystalline films. A kinetic analysis shows that the redshifted emission seen at lower temperatures cannot be an intermediate in the triplet production. When considered in the context of other results, our data suggest that the production of triplets in tetracene for temperatures below 250 K is a complex process that is sensitive to the presence of structural defects.
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Affiliation(s)
- Chad D Cruz
- Department of Chemistry, University of California Riverside, Riverside, California 92521, USA
| | - Eric L Chronister
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, Nevada 89154, USA
| | - Christopher J Bardeen
- Department of Chemistry, University of California Riverside, Riverside, California 92521, USA
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10
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Wang G, Zhang C, Liu Z, Wang R, Ma H, Wang X, Xiao M. Singlet Fission Dynamics in Tetracene Single Crystals Probed by Polarization-Dependent Two-Dimensional Electronic Spectroscopy. J Phys Chem A 2020; 124:10447-10456. [PMID: 33290074 DOI: 10.1021/acs.jpca.0c08440] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The exact mechanism of endothermic singlet fission in crystalline polyacene remains to be clarified. It has been elusive whether the excess energy of vibrational hot states and the upper branch of Davydov splitting is important for the energy compensation. Here, we probe the excited-state specified singlet fission dynamics in tetracene single crystals by polarization-dependent two-dimensional electronic spectroscopy (2DES). While a major spectral transfer with a characteristic lifetime of 86 ps is observed to be largely independent of the excitation energy due to formation of the spatially separated triplet pairs (1(T···T)), the excitation-energy dependent subpicosecond dynamics show marked differences for different states probed, implying the possible involvement of a coherently formed triplet pair state (1(TT)). Analysis of coherent vibrational modes suggests the coupling to high energy modes may offset the energy difference between singlet and triplet pair states. Moreover, the beating map of the low frequency mode indicates a vibrational hot state violating the aggregation behavior of Davydov exciton, which can be explained as a resonance of the 1(TT) state. These results suggest that the coherent vibronic mixing between local excitation and triplet pair states is essential for the singlet fission dynamics in molecule aggregates.
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Affiliation(s)
- Guodong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Zhixing Liu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Rui Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Haibo Ma
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China.,Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
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11
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Van Schenck JDB, Mayonado G, Anthony JE, Graham MW, Ostroverkhova O. Molecular packing-dependent exciton dynamics in functionalized anthradithiophene derivatives: From solutions to crystals. J Chem Phys 2020; 153:164715. [PMID: 33138416 DOI: 10.1063/5.0026072] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Understanding the impact of inter-molecular orientation on the optical properties of organic semiconductors is important for designing next-generation organic (opto)electronic and photonic devices. However, fundamental aspects of how various features of molecular packing in crystalline systems determine the nature and dynamics of excitons have been a subject of debate. Toward this end, we present a systematic study of how various molecular crystal packing motifs affect the optical properties of a class of high-performance organic semiconductors: functionalized derivatives of fluorinated anthradithiophene. The absorptive and emissive species present in three such derivatives (exhibiting "brickwork," "twisted-columnar," and "sandwich-herringbone" motifs, controlled by the side group R) were analyzed both in solution and in single crystals, using various modalities of optical and photoluminescence spectroscopy, revealing the nature of these excited states. In solution, in the emission band, two states were identified: a Franck-Condon state present at all concentrations and an excimer that emerged at higher concentrations. In single crystal systems, together with ab initio calculations, it was found in the absorptive band that Frenkel and Charge Transfer (CT) excitons mixed due to nonvanishing CT integrals in all derivatives, but the amount of admixture and exciton delocalization depended on the packing, with the "sandwich-herringbone" packing motif least conducive to delocalization. Three emissive species in the crystal phase were also identified: Frenkel excitons, entangled triplet pairs 1(TT) (which are precursors to forming free triplet states via singlet fission), and self-trapped excitons (STEs, similar in origin to excimers present in concentrated solution). The "twisted-columnar" packing motif was most conducive to the formation of Frenkel excitons delocalized over 4-7 molecules depending on the temperature. These delocalized Frenkel states were dominant across the full temperature range (78 K-293 K), though at lower temperatures, the entangled triplet states and STEs were present. In the derivative with the "brickwork" packing, all three emissive species were observed across the full temperature range and, most notably, the 1(TT) state was present at room temperature. Finally, the derivative with the "sandwich-herringbone" packing exhibited localized Frenkel excitons and had a strong propensity for self-trapped exciton formation even at higher temperatures. In this derivative, no formation of the 1(TT) state was observed. The temperature-dependent dynamics of these emissive states are reported, as well as their origin in fundamental inter-molecular interactions.
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Affiliation(s)
- J D B Van Schenck
- Department of Physics, Oregon State University, Corvallis, Oregon 97330, USA
| | - G Mayonado
- Department of Physics, Oregon State University, Corvallis, Oregon 97330, USA
| | - J E Anthony
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, USA
| | - M W Graham
- Department of Physics, Oregon State University, Corvallis, Oregon 97330, USA
| | - O Ostroverkhova
- Department of Physics, Oregon State University, Corvallis, Oregon 97330, USA
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12
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Kwang SY, Frontiera RR. Spatially Offset Femtosecond Stimulated Raman Spectroscopy: Observing Exciton Transport through a Vibrational Lens. J Phys Chem Lett 2020; 11:4337-4344. [PMID: 32427490 DOI: 10.1021/acs.jpclett.0c01114] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
To design better molecular electronic devices, we need a strong understanding of how charges or excitons propagate, as many efficiency losses arise during transport. Exciton transport has been difficult to study because excitons tend to be short-lived, have short diffusion lengths, and can easily recombine. Here, we debut spatially offset femtosecond stimulated Raman spectroscopy (SO-FSRS), a three-pulse ultrafast microscopy technique. By offsetting the photoexcitation beam, we can monitor Raman spectral changes as a function of both time and position. We used SO-FSRS on 6,13-bis(triisopropylsilylethynyl) pentacene, a well-studied organic semiconductor used in photovoltaics and field-effect transistors. We demonstrated that the fast exciton and free charge carrier transport axes are identical and observed that exciton transport is less anisotropic by a factor of ∼3. SO-FSRS is the first technique that directly tracks molecular structural evolution during exciton transport, which can provide roadmaps for tailor-making molecules for specific electronic devices.
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Affiliation(s)
- Siu Yi Kwang
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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13
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Manna B, Nandi A. Exploration of photophysics and presence of Long singlet exciton diffusion length in dibenz[a,h]anthracene nanoaggregates. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112407] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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14
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Aggarwal N, Patnaik A. Dimeric conformation sensitive electronic excited states of tetracene congeners and their unconventional non-fluorescent behaviour. J CHEM SCI 2019. [DOI: 10.1007/s12039-019-1626-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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15
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Ellis SR, Dietze DR, Rangel T, Brown-Altvater F, Neaton JB, Mathies RA. Resonance Raman Characterization of Tetracene Monomer and Nanocrystals: Excited State Lattice Distortions With Implications For Efficient Singlet Fission. J Phys Chem A 2019; 123:3863-3875. [PMID: 30952191 DOI: 10.1021/acs.jpca.9b02986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The characterization of specific phonon modes and exciton states that lead to efficient singlet fission (SF) may be instrumental in the design of the next generation of high-efficiency photovoltaic devices. To this end, we analyze the absolute resonance Raman (RR) cross sections for tetracene (Tc) both as a monomer in solution and as a crystalline solid in an aqueous suspension of nanocrystals. For both systems, a time-dependent wavepacket model is developed that is consistent with the absolute RR cross sections, the magnitude of the absorption cross sections, and the vibronic line shapes of the fluorescence. In the monomer, the intramolecular reorganization energy is between 1500 and 1800 cm-1 and the solvent reorganization energy is 70 cm-1. In nanocrystals, the total reorganization is diminished to less than 600 cm-1. The lowest energy exciton has an estimated intramolecular reorganization energy between 300 and 500 cm-1 while intermolecular librational phonons have a reorganization energy of about 130 cm-1. The diminished reorganization energy of the nanocrystal is interpreted in the context of the delocalization of the band-edge exciton onto about ∼7 molecules. When electron and electron-hole correlations are included within many-body perturbation theory, the polarized absorption spectra of crystalline Tc are calculated and found to be in agreement with experiment. The low-lying exciton states and optically active phonons that contribute to the polarized crystal absorption are identified. The likely role of coherent exciton phonon evolution in the SF process is discussed.
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Affiliation(s)
- Scott R Ellis
- Department of Chemistry, MC 1460 , University of California at Berkeley , Berkeley , California 94720 , United States
| | - Daniel R Dietze
- Department of Chemistry, MC 1460 , University of California at Berkeley , Berkeley , California 94720 , United States
| | - Tonatiuh Rangel
- Department of Physics, MC 7300 , University of California at Berkeley , Berkeley , California 94720 , United States
| | - Florian Brown-Altvater
- Department of Physics, MC 7300 , University of California at Berkeley , Berkeley , California 94720 , United States
| | - Jeffrey B Neaton
- Department of Physics, MC 7300 , University of California at Berkeley , Berkeley , California 94720 , United States
| | - Richard A Mathies
- Department of Chemistry, MC 1460 , University of California at Berkeley , Berkeley , California 94720 , United States
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Abstract
This account aims at providing an understanding of singlet fission, i.e., the photophysical process of a singlet state ( S1) splitting into two triplet states (2 × T1) in molecular chromophores. Since its discovery 50 years ago, the field of singlet fission has enjoyed rapid expansion in the past 8 years. However, there have been lingering confusion and debates on the nature of the all-important triplet pair intermediate states and the definition of singlet fission rates. Here we clarify the confusion from both theoretical and experimental perspectives. We distinguish the triplet pair state that maintains electronic coherence between the two constituent triplets, 1(TT), from one which does not, 1(T···T). Only the rate of formation of 1(T···T) is defined as that of singlet fission. We present distinct experimental evidence for 1(TT), whose formation may occur via incoherent and/or vibronic coherent mechanisms. We discuss the challenges in treating singlet fission beyond the dimer approximation, in understanding the often neglected roles of delocalization on singlet fission rates, and in realizing the much lauded goal of increasing solar energy conversion efficiencies with singlet fission chromophores.
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Affiliation(s)
- Kiyoshi Miyata
- Department of Chemistry , Columbia University , New York , New York 10027 , United States.,Department of Chemistry , Kyushu University , Fukuoka 819-0395 , Japan
| | - Felisa S Conrad-Burton
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - Florian L Geyer
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - X-Y Zhu
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
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17
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Wan Y, Wiederrecht GP, Schaller RD, Johnson JC, Huang L. Transport of Spin-Entangled Triplet Excitons Generated by Singlet Fission. J Phys Chem Lett 2018; 9:6731-6738. [PMID: 30403874 DOI: 10.1021/acs.jpclett.8b02944] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Singlet fission provides a promising route for overcoming the Shockley-Queisser limit in solar cells using organic materials. Despite singlet fission dynamics having been extensively investigated, the transport of the various intermediates in relation to the singlet and triplet states is largely unknown. Here we employ temperature-dependent ultrafast transient absorption microscopy to image the transport of singlet fission intermediates in single crystals of tetracene. These measurements suggest a mobile singlet fission intermediate state at low temperatures, with a diffusion constant of 36 cm2s-1 at 5 K, approaching that for the free singlet excitons, which we attribute to the spin-entangled correlated triplet pair state 1[TT]. These results indicate that 1[TT] could transport with a similar mechanism as the bright singlet excitons, which has important implications in designing materials for singlet fission and spintronic applications.
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Affiliation(s)
- Yan Wan
- College of Chemistry , Beijing Normal University , Beijing 100875 , China
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Gary P Wiederrecht
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Richard D Schaller
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Justin C Johnson
- National Renewable Energy Laboratory , 15013 Denver West Pkwy , Golden , Colorado 80401 , United States
| | - Libai Huang
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
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18
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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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19
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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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20
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Morrison AF, Herbert JM. Evidence for Singlet Fission Driven by Vibronic Coherence in Crystalline Tetracene. J Phys Chem Lett 2017; 8:1442-1448. [PMID: 28277682 DOI: 10.1021/acs.jpclett.7b00230] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Singlet fission proceeds rapidly and with high quantum efficiency in both crystalline tetracene and pentacene, which poses a conundrum given that the process in tetracene is disfavored by the electronic energetics. Here, we use an ab initio exciton model to compute nonadiabatic couplings in the unit cell of tetracene in order to identify the modes that promote this process. Four intramolecular modes in the range of 1400-1600 cm-1, which are nearly resonant with the single-exciton/multiexciton energy gap, appear to play a key role. Ab initio calculations of the electron/phonon coupling constants for these modes reveal that they are almost entirely of "Holstein" type, modulating the site energies rather than the intersite couplings. The constants are used to parametrize a vibronic Hamiltonian, simulations with which suggest a vibronically coherent singlet fission mechanism that proceeds spontaneously despite unfavorable electronic energetics. In the absence of vibronic coupling, there is no significant fission according to our model.
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Affiliation(s)
- Adrian F Morrison
- Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
| | - John M Herbert
- Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
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Korovina NV, Das S, Nett Z, Feng X, Joy J, Haiges R, Krylov AI, Bradforth SE, Thompson ME. Singlet Fission in a Covalently Linked Cofacial Alkynyltetracene Dimer. J Am Chem Soc 2016; 138:617-27. [PMID: 26693957 DOI: 10.1021/jacs.5b10550] [Citation(s) in RCA: 185] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Singlet fission is a process in which a singlet exciton converts into two triplet excitons. To investigate this phenomenon, we synthesized two covalently linked 5-ethynyl-tetracene (ET) dimers with differing degrees of intertetracene overlap: BET-X, with large, cofacial overlap of tetracene π-orbitals, and BET-B, with twisted arrangement between tetracenes exhibits less overlap between the tetracene π-orbitals. The two compounds were crystallographically characterized and studied by absorption and emission spectroscopy in solution, in PMMA and neat thin films. The results show that singlet fission occurs within 1 ps in an amorphous thin film of BET-B with high efficiency (triplet yield: 154%). In solution and the PMMA matrix the S1 of BET-B relaxes to a correlated triplet pair (1)(T1T1) on a time scale of 2 ps, which decays to the ground state without forming separated triplets, suggesting that triplet energy transfer from (1)(T1T1) to a nearby chromophore is essential for producing free triplets. In support of this hypothesis, selective excitation of BET-B doped into a thin film of diphenyltetracene (DPT) leads to formation of the (1)(T1T1) state of BET-B, followed by generation of both DPT and BET-B triplets. For the structurally cofacial BET-X, an intermediate forms in <180 fs and returns to the ground state more rapidly than BET-B. First-principles calculations predict a 2 orders of magnitude faster rate of singlet fission to the (1)(T1T1) state in BET-B relative to that of crystalline tetracene, attributing the rate increase to greater coupling between the S1 and (1)(T1T1) states and favorable energetics for formation of the separated triplets.
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Affiliation(s)
- Nadezhda V Korovina
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Saptaparna Das
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Zachary Nett
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Xintian Feng
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Jimmy Joy
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Ralf Haiges
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Anna I Krylov
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Stephen E Bradforth
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Mark E Thompson
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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22
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Davydova D, de la Cadena A, Demmler S, Rothhardt J, Limpert J, Pascher T, Akimov D, Dietzek B. Ultrafast transient absorption microscopy: Study of excited state dynamics in PtOEP crystals. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2015.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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23
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Margulies EA, Wu YL, Gawel P, Miller SA, Shoer LE, Schaller RD, Diederich F, Wasielewski MR. Sub-Picosecond Singlet Exciton Fission in Cyano-Substituted Diaryltetracenes. Angew Chem Int Ed Engl 2015; 54:8679-83. [PMID: 26097009 DOI: 10.1002/anie.201501355] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 04/14/2015] [Indexed: 11/12/2022]
Abstract
Thin films of 5,11-dicyano-6,12-diphenyltetracene (TcCN) have been studied for their ability to undergo singlet exciton fission (SF). Functionalization of tetracene with cyano substituents yields a more stable chromophore with favorable energetics for exoergic SF (2E(T1)-E(S1)=-0.17 eV), where S1 and T1 are singlet and triplet excitons, respectively. As a result of tuning the triplet-state energy, SF is faster in TcCN relative to the corresponding endoergic process in tetracene. SF proceeds with two time constants in the film samples (τ=0.8±0.2 ps and τ=23±3 ps), which is attributed to structural disorder within the film giving rise to one population with a favorable interchromophore geometry, which undergoes rapid SF, and a second population in which the initially formed singlet exciton must diffuse to a site at which this favorable geometry exists. A triplet yield analysis using transient absorption spectra indicates the formation of 1.6±0.3 triplets per initial excited state.
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Affiliation(s)
- Eric A Margulies
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA)
| | - Yi-Lin Wu
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA)
| | - Przemyslaw Gawel
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich (Switzerland)
| | - Stephen A Miller
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA)
| | - Leah E Shoer
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA)
| | - Richard D Schaller
- Department of Chemistry, Northwestern University and Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439 (USA)
| | - François Diederich
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich (Switzerland).
| | - Michael R Wasielewski
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA).
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24
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Margulies EA, Wu YL, Gawel P, Miller SA, Shoer LE, Schaller RD, Diederich F, Wasielewski MR. Sub-Picosecond Singlet Exciton Fission in Cyano-Substituted Diaryltetracenes. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201501355] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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25
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Abstract
The dependence of exciton dynamics on the crystalline morphology of tetracene is investigated using time-resolved photoluminescence. Single crystals exhibit relatively slow singlet decays with times that range from 130 to 300 ps depending on the sample. This decay has an activation energy of ∼450 cm(-1) over the temperature range of 200-400 K. Single-crystal samples also exhibit more pronounced quantum beats due to the triplet pair spin coherences. Polycrystalline thin films grown by thermal evaporation have singlet decay times on the order of 70-90 ps with a much weaker temperature dependence. Many thin-film samples also exhibit a red-shifted excimer-like emission. When a polycrystalline thin film is thermally annealed to produce larger crystal domains, single-crystal behavior is recovered. We hypothesize that the different dynamics arise from the ability of singlet excitons in the thin films to sample regions with defects or packing motifs that accelerate singlet fission.
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Affiliation(s)
- Geoffrey B Piland
- Department of Chemistry, University of California, Riverside, Riverside, California 92506, United States
| | - Christopher J Bardeen
- Department of Chemistry, University of California, Riverside, Riverside, California 92506, United States
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26
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Eaton SW, Miller SA, Margulies EA, Shoer LE, Schaller RD, Wasielewski MR. Singlet exciton fission in thin films of tert-butyl-substituted terrylenes. J Phys Chem A 2015; 119:4151-61. [PMID: 25856414 DOI: 10.1021/acs.jpca.5b02719] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two terrylene chromophores, 2,5,10,13-tetra(tert-butyl)terrylene (1) and 2,5-di(tert-butyl)terrylene (2), were synthesized and studied to determine their singlet exciton fission (SF) efficiencies. Compound 1 crystallizes in one-dimensional stacks, whereas 2 packs in a slip-stacked, herringbone pattern of dimers motif. Strongly quenched fluorescence and rapid singlet exciton decay dynamics are observed in vapor-deposited thin films of 1 and 2. Phosphorescence measurements on thin films of 1 and 2 show that SF is only 70 meV endoergic for these chromophores. Femtosecond transient absorption experiments using low laser fluences on these films reveal rapid triplet exciton formation for both 1 (τ = 120 ± 10 ps) and 2 (τ = 320 ± 20 ps) that depends strongly on film crystallinity. The transient absorption data are consistent with formation of an excimer state prior to SF. Triplet exciton yield measurements indicate nearly quantitative SF in thin films of both chromophores in highly crystalline solvent-vapor-annealed films: 170 ± 20% for 1 and 200 ± 30% for 2. These results show that significantly different crystal morphologies of the same chromophore can both result in high-efficiency SF provided that the energetics are favorable.
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Affiliation(s)
| | | | | | | | - Richard D Schaller
- §Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439-4803, United States
| | - Michael R Wasielewski
- §Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439-4803, United States
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27
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Zhang YJ, Li P, Cai L, Xiang J, Ding BF, Alameh K, Song QL. A simple and cost effective experimental method for verifying singlet fission in pentacene–C60 solar cells. RSC Adv 2015. [DOI: 10.1039/c5ra04197j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The singlet fission in pentacene–C60 solar cells is verified by comparing the experimental and calculated EQE based on the distribution (f1(x)) and the diffusion probability (f2(x)) of excitons.
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Affiliation(s)
- Yu Jun Zhang
- Institute for Clean Energy & Advanced Materials
- Faculty of Materials and Energy
- Southwest University
- Chongqing 400715
- P. R. China
| | - Ping Li
- Institute for Clean Energy & Advanced Materials
- Faculty of Materials and Energy
- Southwest University
- Chongqing 400715
- P. R. China
| | - Lun Cai
- Institute for Clean Energy & Advanced Materials
- Faculty of Materials and Energy
- Southwest University
- Chongqing 400715
- P. R. China
| | - Jin Xiang
- Institute for Clean Energy & Advanced Materials
- Faculty of Materials and Energy
- Southwest University
- Chongqing 400715
- P. R. China
| | - Bao Fu Ding
- Electron Science Research Institute
- Edith Cowan University
- Joondalup
- Australia
| | - Kamal Alameh
- Electron Science Research Institute
- Edith Cowan University
- Joondalup
- Australia
| | - Qun Liang Song
- Institute for Clean Energy & Advanced Materials
- Faculty of Materials and Energy
- Southwest University
- Chongqing 400715
- P. R. China
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28
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Zhang B, Zhang C, Xu Y, Wang R, He B, Liu Y, Zhang S, Wang X, Xiao M. Polarization-dependent exciton dynamics in tetracene single crystals. J Chem Phys 2014; 141:244303. [DOI: 10.1063/1.4904385] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Bo Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yanqing Xu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Rui Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Bin He
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yunlong Liu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Shimeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
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29
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Zhang B, Zhang C, Wang R, Tan Z, Liu Y, Guo W, Zhai X, Cao Y, Wang X, Xiao M. Nonlinear Density Dependence of Singlet Fission Rate in Tetracene Films. J Phys Chem Lett 2014; 5:3462-3467. [PMID: 26278594 DOI: 10.1021/jz501736y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Singlet fission holds the potential to dramatically improve the efficiency of solar energy conversion by creating two triplet excitons from one photoexcited singlet exciton in organic semiconductors. It is generally assumed that the singlet-fission rate is linearly dependent on the exciton density. Here we experimentally show that the rate of singlet fission has a nonlinear dependence on the density of photoexcited singlet excitons in tetracene films with small crystalline grains. We disentangle the spectrotemporal features of singlet and triplet dynamics from ultrafast spectroscopic data with the algorithm of singular value decomposition. The correlation between their temporal dynamics indicates a superlinear dependence of fission rate on the density of singlet excitons, which may arise from excitonic interactions.
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Affiliation(s)
| | | | | | - Zhanao Tan
- ‡New and Renewable Energy of Beijing Key Laboratory, School of Renewable Energy, North China Electric Power University, Beijing 102206, China
| | | | | | | | | | | | - Min Xiao
- §Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
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