101
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Benchmarking singlet and triplet excitation energies of molecular semiconductors for singlet fission: Tuning the amount of HF exchange and adjusting local correlation to obtain accurate functionals for singlet–triplet gaps. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2016.08.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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102
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Singlet Fission: Optimization of Chromophore Dimer Geometry. ADVANCES IN QUANTUM CHEMISTRY 2017. [DOI: 10.1016/bs.aiq.2017.03.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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103
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McDonough TJ, Zhang L, Roy SS, Kearns NM, Arnold MS, Zanni MT, Andrew TL. Triplet exciton dissociation and electron extraction in graphene-templated pentacene observed with ultrafast spectroscopy. Phys Chem Chem Phys 2017; 19:4809-4820. [DOI: 10.1039/c6cp06454j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Transient absorption measurements of pentacene, controlling molecular orientation (via graphene templating), fluence, and polarization, provide new evidence for charge generation.
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Affiliation(s)
| | - Lushuai Zhang
- Department of Materials Science and Engineering
- University of Wisconsin–Madison
- Madison
- USA
| | - Susmit Singha Roy
- Department of Materials Science and Engineering
- University of Wisconsin–Madison
- Madison
- USA
| | | | - Michael S. Arnold
- Department of Materials Science and Engineering
- University of Wisconsin–Madison
- Madison
- USA
| | - Martin T. Zanni
- Department of Chemistry
- University of Wisconsin–Madison
- Madison
- USA
| | - Trisha L. Andrew
- Department of Chemistry
- University of Wisconsin–Madison
- Madison
- USA
- Department of Materials Science and Engineering
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104
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Margulies EA, Logsdon JL, Miller CE, Ma L, Simonoff E, Young RM, Schatz GC, Wasielewski MR. Direct Observation of a Charge-Transfer State Preceding High-Yield Singlet Fission in Terrylenediimide Thin Films. J Am Chem Soc 2016; 139:663-671. [PMID: 27977196 DOI: 10.1021/jacs.6b07721] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Singlet exciton fission (SF) in organic chromophore assemblies results in the conversion of one singlet exciton (S1) into two triplet excitons (T1), provided that the overall process is exoergic, i.e., E(S1) > 2E(T1). We report on SF in thin polycrystalline films of two terrylene-3,4:11,12-bis(dicarboximide) (TDI) derivatives 1 and 2, which crystallize into two distinct π-stacked structures. Femtosecond transient absorption spectroscopy (fsTA) reveals a charge-transfer state preceding a 190% T1 yield in films of 1, where the π-stacked TDI molecules are rotated by 23° along an axis perpendicular to their π systems. In contrast, when the TDI molecules are slip-stacked along their N-N axes in films of 2, fsTA shows excimer formation, followed by a 50% T1 yield.
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Affiliation(s)
- Eric A Margulies
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Jenna L Logsdon
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Claire E Miller
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Lin Ma
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Ethan Simonoff
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Ryan M Young
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - George C Schatz
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Michael R Wasielewski
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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105
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Xie X, Ma H. Opposite Anisotropy Effects of Singlet and Triplet Exciton Diffusion in Tetracene Crystal. ChemistryOpen 2016; 5:201-205. [PMID: 27933226 PMCID: PMC5126140 DOI: 10.1002/open.201500214] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Indexed: 11/10/2022] Open
Abstract
We observe the diffusion anisotropy difference between singlet and triplet excitons in organic crystals; that is, singlet and triplet excitons may have completely different spatial direction preference for diffusion. This phenomenon can be ascribed to the distinct dependence of different excitonic couplings (Coulomb Förster vs. exchange Dexter) existing in singlet and triplet excitons on their intermolecular distance and intermolecular orientation. Such a discovery provides insights for understanding the fundamental photophysical process in a vast range of organic condensed-phase systems and optimizing the efficiency of organic optoelectronic materials.
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Affiliation(s)
- Xiaoyu Xie
- Key Laboratory of Mesoscopic Chemistry of the Ministry of Education (MOE) Collaborative Innovation Centre of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210093 P. R. China
| | - Haibo Ma
- Key Laboratory of Mesoscopic Chemistry of the Ministry of Education (MOE) Collaborative Innovation Centre of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210093 P. R. China
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106
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Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering. Nat Commun 2016; 7:13622. [PMID: 27924819 PMCID: PMC5150654 DOI: 10.1038/ncomms13622] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 10/17/2016] [Indexed: 12/23/2022] Open
Abstract
Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics.
The understanding of how a singlet exciton separates into triplet states in organic semiconductors is crucial to the design of efficient organic solar cells. Here, Lukman et al. identify the role played by charge-transfer states during triplet formation through side-group engineering of pentacenes.
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107
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Grieco C, Doucette GS, Pensack RD, Payne MM, Rimshaw A, Scholes GD, Anthony JE, Asbury JB. Dynamic Exchange During Triplet Transport in Nanocrystalline TIPS-Pentacene Films. J Am Chem Soc 2016; 138:16069-16080. [DOI: 10.1021/jacs.6b10010] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher Grieco
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Grayson S. Doucette
- Intercollege
Materials Science and Engineering Program, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ryan D. Pensack
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Marcia M. Payne
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Adam Rimshaw
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Gregory D. Scholes
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - John E. Anthony
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - John B. Asbury
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Intercollege
Materials Science and Engineering Program, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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108
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Le AK, Bender JA, Roberts ST. Slow Singlet Fission Observed in a Polycrystalline Perylenediimide Thin Film. J Phys Chem Lett 2016; 7:4922-4928. [PMID: 27934043 DOI: 10.1021/acs.jpclett.6b02320] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Singlet exciton fission (SF) is a process wherein an exciton in an organic semiconductor divides its energy to form two excitations. This process can offset thermalization losses in light harvesting technologies, but requires photostable materials with high SF efficiency. We report ultrafast kinetics of polycrystalline films of N-N'-dioctyl-3,4,9,10-perylenedicarboximide (C8-PDI), a chromophore predicted to undergo SF on picosecond time scales. While transient absorption measurements display picosecond dynamics, such kinetics are absent from low-fluence time-resolved emission experiments, indicating they result from singlet-singlet exciton annihilation. A model that accounts for annihilation can reproduce both measurements and highlights that care must be taken when extracting SF rates from time-resolved data. Our model also reveals SF proceeds in C8-PDI over 3.8 ns. Despite this slow rate, SF occurs in high yield (51%) due to a lack of competing singlet deactivation pathways. Our results show perylenediimides are a promising class of SF materials that merit further study.
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Affiliation(s)
- Aaron K Le
- Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712-1224, United States
| | - Jon A Bender
- Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712-1224, United States
| | - Sean T Roberts
- Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712-1224, United States
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109
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110
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Mauck CM, Hartnett PE, Margulies EA, Ma L, Miller CE, Schatz GC, Marks TJ, Wasielewski MR. Singlet Fission via an Excimer-Like Intermediate in 3,6-Bis(thiophen-2-yl)diketopyrrolopyrrole Derivatives. J Am Chem Soc 2016; 138:11749-61. [PMID: 27547986 DOI: 10.1021/jacs.6b05627] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Singlet fission (SF) in polycrystalline thin films of four 3,6-bis(thiophen-2-yl)diketopyrrolopyrrole (TDPP) chromophores with methyl (Me), n-hexyl (C6), triethylene glycol (TEG), and 2-ethylhexyl (EH) substituents at the 2,5-positions is found to involve an intermediate excimer-like state. The four different substituents yield four distinct intermolecular packing geometries, resulting in variable intermolecular charge transfer (CT) interactions in the solid. SF from the excimer state of Me, C6, TEG, and EH takes place in τSF = 22, 336, 195, and 1200 ps, respectively, to give triplet yields of 200%, 110%, 110%, and 70%, respectively. The transient spectra of the excimer-like state and its energetic proximity to the lowest excited singlet state in these derivatives suggests that this state may be the multiexciton (1)(T1T1) state that precedes formation of the uncorrelated triplet excitons. The excimer decay rates correlate well with the SF efficiencies and the degree of intermolecular donor-acceptor interactions resulting from π-stacking of the thiophene donor of one molecule with the DPP core acceptor in another molecule as observed in the crystal structures. Such interactions are found to also increase with the SF coupling energies, as calculated for each derivative. These structural and spectroscopic studies afford a better understanding of the electronic interactions that enhance SF in chromophores having strong intra- and intermolecular CT character.
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Affiliation(s)
- Catherine M Mauck
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Patrick E Hartnett
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Eric A Margulies
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Lin Ma
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Claire E Miller
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - George C Schatz
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Tobin J Marks
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Michael R Wasielewski
- Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and Institute for Sustainability and Energy at Northwestern, Northwestern University , Evanston, Illinois 60208-3113, United States
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111
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Margulies EA, Miller CE, Wu Y, Ma L, Schatz GC, Young RM, Wasielewski MR. Enabling singlet fission by controlling intramolecular charge transfer in π-stacked covalent terrylenediimide dimers. Nat Chem 2016; 8:1120-1125. [PMID: 27874873 DOI: 10.1038/nchem.2589] [Citation(s) in RCA: 192] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 07/01/2016] [Indexed: 01/05/2023]
Abstract
When an assembly of two or more molecules absorbs a photon to form a singlet exciton, and the energetics and intermolecular interactions are favourable, the singlet exciton can rapidly and spontaneously produce two triplet excitons by singlet fission. To understand this process is important because it may prove to be technologically significant for enhancing solar-cell performance. Theory strongly suggests that charge-transfer states are involved in singlet fission, but their role has remained an intriguing puzzle and, up until now, no molecular system has provided clear evidence for such a state. Here we describe a terrylenediimide dimer that forms a charge-transfer state in a few picoseconds in polar solvents, and undergoes equally rapid, high-yield singlet fission in nonpolar solvents. These results show that adjusting the charge-transfer-state energy relative to those of the exciton states can serve to either inhibit or promote singlet fission.
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Affiliation(s)
- Eric A Margulies
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Claire E Miller
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Yilei Wu
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Lin Ma
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - George C Schatz
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Ryan M Young
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
| | - Michael R Wasielewski
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA
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112
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Lian S, Weinberg DJ, Harris RD, Kodaimati MS, Weiss EA. Subpicosecond Photoinduced Hole Transfer from a CdS Quantum Dot to a Molecular Acceptor Bound Through an Exciton-Delocalizing Ligand. ACS NANO 2016; 10:6372-6382. [PMID: 27281685 DOI: 10.1021/acsnano.6b02814] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This paper describes the enhancement of the rate of hole transfer from a photoexcited CdS quantum dot (QD), with radius R = 2.0 nm, to a molecular acceptor, phenothiazine (PTZ), by linking the donor and acceptor through a phenyldithiocarbamate (PTC) linker, which is known to lower the confinement energy of the excitonic hole. Upon adsorption of PTC, the bandgap of the QD decreases due to delocalization of the exciton, primarily the excitonic hole, into interfacial states of mixed QD/PTC character. This delocalization enables hole transfer from the QD to PTZ in <300 fs (within the instrument response of the laser system) when linked by PTC, but not when linked by a benzoate group, which has a similar length and conjugation as PTC but does not delocalize the excitonic hole. Comparison of the two systems was aided by quantification of the surface coverage of benzoate and PTC-linked PTZ by (1)H NMR. This work provides direct spectroscopic evidence of the enhancement of the rate of hole extraction from a colloidal QD through covalent linkage of a hole acceptor through an exciton-delocalizing ligand.
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Affiliation(s)
- Shichen Lian
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - David J Weinberg
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - Rachel D Harris
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - Mohamad S Kodaimati
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - Emily A Weiss
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
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113
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Cook JD, Carey TJ, Damrauer NH. Solution-Phase Singlet Fission in a Structurally Well-Defined Norbornyl-Bridged Tetracene Dimer. J Phys Chem A 2016; 120:4473-81. [PMID: 27291516 DOI: 10.1021/acs.jpca.6b04367] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photophysics of a norbornyl-bridged covalent tetracene (Tc) dimer BT1 and a monomer analogue Tc-e were studied in room-temperature nonpolar solvents. Notably in BT1, a Davydov-split band is observed in UV absorption, heralding interchromophore electronic interactions. Emission spectra indicate an acene-like vibronic progression mirroring the lowest-energy visible absorption. For BT1, this argues against excited-state excimer formation. Evidence of intramolecular singlet fission (SF) comes from a comparison of time-resolved emission decay signals collected for BT1 versus Tc-e in toluene. In BT1, the multiexcitonic (1)TT state is produced in 70 ns in 6% yield. A ratio of fission versus fusion rate constants provides an experimental measure of the SF reaction free energy at 52 meV in good agreement with previous calculations. The low SF yield corroborates our expectations that orbital symmetry effects on diabatic coupling for SF are important for dimers that cannot rely on more favorable thermodynamics.
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Affiliation(s)
- Jasper D Cook
- Department of Chemistry and Biochemistry, University of Colorado , Boulder Colorado 80309, United States
| | - Thomas J Carey
- Department of Chemistry and Biochemistry, University of Colorado , Boulder Colorado 80309, United States
| | - Niels H Damrauer
- Department of Chemistry and Biochemistry, University of Colorado , Boulder Colorado 80309, United States
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114
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Zhang YD, Wu Y, Xu Y, Wang Q, Liu K, Chen JW, Cao JJ, Zhang C, Fu H, Zhang HL. Excessive Exoergicity Reduces Singlet Exciton Fission Efficiency of Heteroacenes in Solutions. J Am Chem Soc 2016; 138:6739-45. [DOI: 10.1021/jacs.6b03829] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- You-Dan Zhang
- State Key Laboratory of Applied Organic
Chemistry (SKLAOC), Key Laboratory of Special Function Materials and
Structure Design (MOE), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Yishi Wu
- Beijing National Laboratory for Molecules Science (BNLMS),
State Key Laboratory for Structural Chemistry of Unstable and Stable
Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Yanqing Xu
- National Laboratory of Solid State Microstructures, School
of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Qiang Wang
- State Key Laboratory of Applied Organic
Chemistry (SKLAOC), Key Laboratory of Special Function Materials and
Structure Design (MOE), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Ke Liu
- State Key Laboratory of Applied Organic
Chemistry (SKLAOC), Key Laboratory of Special Function Materials and
Structure Design (MOE), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Jian-Wei Chen
- Beijing National Laboratory for Molecules Science (BNLMS),
State Key Laboratory for Structural Chemistry of Unstable and Stable
Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Jing-Jing Cao
- State Key Laboratory of Applied Organic
Chemistry (SKLAOC), Key Laboratory of Special Function Materials and
Structure Design (MOE), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School
of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Hongbing Fu
- Beijing National Laboratory for Molecules Science (BNLMS),
State Key Laboratory for Structural Chemistry of Unstable and Stable
Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Hao-Li Zhang
- State Key Laboratory of Applied Organic
Chemistry (SKLAOC), Key Laboratory of Special Function Materials and
Structure Design (MOE), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
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115
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Dijkstra AG, Duan HG, Knoester J, Nelson KA, Cao J. How two-dimensional brick layer J-aggregates differ from linear ones: Excitonic properties and line broadening mechanisms. J Chem Phys 2016; 144:134310. [DOI: 10.1063/1.4944980] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- Arend G. Dijkstra
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149 Bldg. 99, 22761 Hamburg, Germany
| | - Hong-Guang Duan
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149 Bldg. 99, 22761 Hamburg, Germany
| | - Jasper Knoester
- Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Keith A. Nelson
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Jianshu Cao
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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116
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Kawata S, Pu YJ, Saito A, Kurashige Y, Beppu T, Katagiri H, Hada M, Kido J. Singlet Fission of Non-polycyclic Aromatic Molecules in Organic Photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:1585-1590. [PMID: 26663207 DOI: 10.1002/adma.201504281] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/14/2015] [Indexed: 06/05/2023]
Abstract
Singlet fission of thienoquinoid compounds in organic photovoltaics is demonstrated. The escalation of the thienoquinoid length of the compounds realizes a suitable packing structure and energy levels for singlet fission. The magnetic-field dependence of the photocurrent and the external quantum efficiency of the devices reveal singlet fission of the compounds and dissociation of triplet excitons into charges.
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Affiliation(s)
- So Kawata
- Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Yong-Jin Pu
- Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
- JST-PRESTO, Kawaguchi, Saitama, 332-0012, Japan
| | - Ayaka Saito
- Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Yuki Kurashige
- JST-PRESTO, Kawaguchi, Saitama, 332-0012, Japan
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi, 444-8585, Japan
| | - Teruo Beppu
- Department of Chemistry and Chemical Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Hiroshi Katagiri
- Department of Chemistry and Chemical Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Masaki Hada
- JST-PRESTO, Kawaguchi, Saitama, 332-0012, Japan
- Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan
| | - Junji Kido
- Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
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117
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Sanders SN, Kumarasamy E, Pun AB, Steigerwald ML, Sfeir MY, Campos LM. Intramolecular Singlet Fission in Oligoacene Heterodimers. Angew Chem Int Ed Engl 2016; 55:3373-7. [DOI: 10.1002/anie.201510632] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Samuel N. Sanders
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Elango Kumarasamy
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Andrew B. Pun
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Michael L. Steigerwald
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Matthew Y. Sfeir
- Center for Functional Nanomaterials; Brookhaven National Laboratory; Building 735 Upton NY 11973 USA
| | - Luis M. Campos
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
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118
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Sanders SN, Kumarasamy E, Pun AB, Steigerwald ML, Sfeir MY, Campos LM. Intramolecular Singlet Fission in Oligoacene Heterodimers. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510632] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Samuel N. Sanders
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Elango Kumarasamy
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Andrew B. Pun
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Michael L. Steigerwald
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
| | - Matthew Y. Sfeir
- Center for Functional Nanomaterials; Brookhaven National Laboratory; Building 735 Upton NY 11973 USA
| | - Luis M. Campos
- Department of Chemistry; Columbia University; 3000 Broadway, MC3124 New York NY 10027 USA
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119
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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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120
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Kasai Y, Tamai Y, Ohkita H, Benten H, Ito S. Ultrafast Singlet Fission in a Push–Pull Low-Bandgap Polymer Film. J Am Chem Soc 2015; 137:15980-3. [DOI: 10.1021/jacs.5b09361] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Yukitomo Kasai
- Department
of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan
| | - Yasunari Tamai
- Department
of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan
| | - Hideo Ohkita
- Department
of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan
- Japan Science and Technology Agency (JST), PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Hiroaki Benten
- Department
of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan
| | - Shinzaburo Ito
- Department
of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan
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121
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Damrauer NH, Snyder JL. Symmetry-directed control of electronic coupling for singlet fission in covalent bis-acene dimers. J Phys Chem Lett 2015; 6:4456-4462. [PMID: 26505732 DOI: 10.1021/acs.jpclett.5b02186] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
While singlet fission (SF) has developed in recent years within material settings, much less is known about its control in covalent dimers. Such platforms are of fundamental importance and may also find practical use in next-generation dye-sensitized solar cell applications or for seeding SF at interfaces following exciton transport. Here, facile theoretical tools based on Boys localization methods are used to predict diabatic coupling for SF via determination of one-electron orbital coupling matrix elements. The results expose important design rules that are rooted in point group symmetry. For Cs-symmetric dimers, pathways for SF that are mediated by virtual charge transfer excited states destructively interfere with negative impact on the magnitude of diabatic coupling for SF. When dimers have C2 symmetry, constructive interference is enabled for certain readily achievable interchromophore orientations. Three sets of dimers exploiting these ideas are explored: a bis-tetracene pair and two sets of aza-substituted tetracene dimers. Remarkable control is shown. In one aza-substituted set, symmetry has no impact on SF reaction thermodynamics but leads to a 16-fold manipulation in SF diabatic coupling. This translates to a difference of nearly 300 in kSF with the faster of the two dimers (C2) being predicted to undergo the process on a nearly ultrafast 1.5 ps time scale.
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Affiliation(s)
- Niels H Damrauer
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - Jamie L Snyder
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
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122
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Teichen PE, Eaves JD. Collective aspects of singlet fission in molecular crystals. J Chem Phys 2015; 143:044118. [PMID: 26233118 DOI: 10.1063/1.4922644] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We present a model to describe collective features of singlet fission in molecular crystals and analyze it using many-body theory. The model we develop allows excitonic states to delocalize over several chromophores which is consistent with the character of the excited states in many molecular crystals, such as the acenes, where singlet fission occurs. As singlet states become more delocalized and triplet states more localized, the rate of singlet fission increases. We also determine the conditions under which the two triplets resulting from fission are correlated. Using the Bethe Ansatz and an entanglement measure for indistinguishable bipartite systems, we calculate the triplet-triplet entanglement as a function of the biexciton interaction strength. The biexciton interaction can produce bound biexciton states and provides a source of entanglement between the two triplets even when the triplets are spatially well separated. Significant entanglement between the triplet pair occurs well below the threshold for bound pair formation. Our results paint a dynamical picture that helps to explain why fission has been observed to be more efficient in molecular crystals than in their covalent dimer analogues and have consequences for photovoltaic efficiency models that assume that the two triplets can be extracted independently.
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Affiliation(s)
- Paul E Teichen
- Department of Chemistry and Biochemistry, The University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Joel D Eaves
- Department of Chemistry and Biochemistry, The University of Colorado at Boulder, Boulder, Colorado 80309, USA
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123
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Arias DH, Ryerson JL, Cook JD, Damrauer NH, Johnson JC. Polymorphism influences singlet fission rates in tetracene thin films. Chem Sci 2015; 7:1185-1191. [PMID: 29910873 PMCID: PMC5975788 DOI: 10.1039/c5sc03535j] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 11/05/2015] [Indexed: 12/21/2022] Open
Abstract
We report the effect of crystal structure and crystallite grain size on singlet fission (SF) in polycrystalline tetracene, one of the most widely studied SF and organic semiconductor materials. SF has been comprehensively studied in one polymoprh (Tc I), but not in the other, less stable polymorph (Tc II). Using carefully controlled thermal evaporation deposition conditions and high sensitivity ultrafast transient absorption spectroscopy, we found that for large crystallite size samples, SF in nearly pure Tc II films is significantly faster than SF in Tc I films. We also discovered that crystallite size has a minimal impact on the SF rate in Tc II films, but a significant influence in Tc I films. Large crystallites exhibit SF times of 125 ps and 22 ps in Tc I and Tc II, respectively, whereas small crystallites have SF times of 31 ps and 33 ps. Our results demonstrate first, that attention must be paid to polymorphism in obtaining a self-consistent rate picture for SF in tetracene and second, that control of polymorphism can play a significant role towards achieving a mechanistic understanding of SF in polycrystalline systems. In this latter context we show that conventional theory based on non-covalent tetracene couplings is insufficient, thus highlighting the need for models that capture the delocalized and highly mobile nature of excited states in elucidating the full photophysical picture.
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Affiliation(s)
- Dylan H Arias
- National Renewable Energy Laboratory , Golden , Colorado 80401 , USA . .,Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , USA .
| | - Joseph L Ryerson
- National Renewable Energy Laboratory , Golden , Colorado 80401 , USA . .,Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , USA .
| | - Jasper D Cook
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , USA .
| | - Niels H Damrauer
- Department of Chemistry and Biochemistry , University of Colorado , Boulder , Colorado 80309 , USA .
| | - Justin C Johnson
- National Renewable Energy Laboratory , Golden , Colorado 80401 , USA .
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124
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Wang W, Liu Q, Zhan C, Barhoumi A, Yang T, Wylie RG, Armstrong PA, Kohane DS. Efficient Triplet-Triplet Annihilation-Based Upconversion for Nanoparticle Phototargeting. NANO LETTERS 2015; 15:6332-8. [PMID: 26158690 DOI: 10.1021/acs.nanolett.5b01325] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
High-efficiency upconverted light would be a desirable stimulus for triggered drug delivery. Here we present a general strategy to achieve photoreactions based on triplet-triplet annihilation upconversion (TTA-UC) and Förster resonance energy transfer (FRET). We designed PLA-PEG micellar nanoparticles containing in their cores hydrophobic photosensitizer and annihilator molecules which, when stimulated with green light, would undergo TTA-UC. The upconverted energy was then transferred by FRET to a hydrophobic photocleavable group (DEACM), also in the core. The DEACM was bonded to (and thus inactivated) the cell-binding peptide cyclo-(RGDfK), which was bound to the PLA-PEG chain. Cleavage of DEACM by FRET reactivated the PLA-PEG-bound peptide and allowed it to move from the particle core to the surface. TTA-UC followed by FRET allowed photocontrolled binding of cell adhesion with green light LED irradiation at low irradiance for short periods. These are attractive properties in phototriggered systems.
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Affiliation(s)
- Weiping Wang
- Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Qian Liu
- Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Changyou Zhan
- Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Aoune Barhoumi
- Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Tianshe Yang
- Institute of Advanced Materials, School of Materials Science and Engineering, Nanjing University of Posts and Telecommunications , 9 Wenyuan Road, Nanjing 210023, People's Republic of China
| | - Ryan G Wylie
- Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Patrick A Armstrong
- Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Daniel S Kohane
- Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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125
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126
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Wan Y, Guo Z, Zhu T, Yan S, Johnson J, Huang L. Cooperative singlet and triplet exciton transport in tetracene crystals visualized by ultrafast microscopy. Nat Chem 2015; 7:785-92. [DOI: 10.1038/nchem.2348] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 09/14/2015] [Indexed: 12/22/2022]
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127
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Sanders SN, Kumarasamy E, Pun AB, Trinh MT, Choi B, Xia J, Taffet EJ, Low JZ, Miller JR, Roy X, Zhu XY, Steigerwald ML, Sfeir MY, Campos LM. Quantitative Intramolecular Singlet Fission in Bipentacenes. J Am Chem Soc 2015; 137:8965-72. [DOI: 10.1021/jacs.5b04986] [Citation(s) in RCA: 272] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Samuel N. Sanders
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Elango Kumarasamy
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Andrew B. Pun
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - M. Tuan Trinh
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Bonnie Choi
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Jianlong Xia
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Elliot J. Taffet
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Jonathan Z. Low
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | | | - Xavier Roy
- 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
| | | | | | - Luis M. Campos
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
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128
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Zhai Y, Sheng C, Vardeny ZV. Singlet fission of hot excitons in π-conjugated polymers. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:20140327. [PMID: 25987576 PMCID: PMC4455724 DOI: 10.1098/rsta.2014.0327] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/22/2014] [Indexed: 05/20/2023]
Abstract
We used steady-state photoinduced absorption (PA), excitation dependence (EXPA(ω)) spectrum of the triplet exciton PA band, and its magneto-PA (MPA(B)) response to investigate singlet fission (SF) of hot excitons into two separated triplet excitons, in two luminescent and non-luminescent π-conjugated polymers. From the high energy step in the triplet EXPA(ω) spectrum of the luminescent polymer poly(dioctyloxy)phenylenevinylene (DOO-PPV) films, we identified a hot-exciton SF (HE-SF) process having threshold energy at E≈2E(T) (=2.8 eV, where ET is the energy of the lowest lying triplet exciton), which is about 0.8 eV above the lowest singlet exciton energy. The HE-SF process was confirmed by the triplet MPA(B) response for excitation at E>2E(T), which shows typical SF response. This process is missing in DOO-PPV solution, showing that it is predominantly interchain in nature. By contrast, the triplet EXPA(ω) spectrum in the non-luminescent polymer polydiacetylene (PDA) is flat with an onset at E=E(g) (≈2.25 eV). From this, we infer that intrachain SF that involves a triplet-triplet pair state, also known as the 'dark' 2A(g) exciton, dominates the triplet photogeneration in PDA polymer as E(g)>2E(T). The intrachain SF process was also identified from the MPA(B) response of the triplet PA band in PDA. Our work shows that the SF process in π-conjugated polymers is a much more general process than thought previously.
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Affiliation(s)
- Yaxin Zhai
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA Materials Research Science and Engineering Center (MRSEC), University of Utah, Salt Lake City, UT 84112, USA
| | - Chuanxiang Sheng
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Z Valy Vardeny
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA Materials Research Science and Engineering Center (MRSEC), University of Utah, Salt Lake City, UT 84112, USA
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129
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Herz J, Buckup T, Paulus F, Engelhart JU, Bunz UHF, Motzkus M. Unveiling Singlet Fission Mediating States in TIPS-pentacene and its Aza Derivatives. J Phys Chem A 2015; 119:6602-10. [DOI: 10.1021/acs.jpca.5b02212] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Julia Herz
- Physikalisch-Chemisches
Institut, Im Neuenheimer
Feld 229, ‡Organisch-Chemisches Institut, Im Neuenheimer Feld 270, and §Centre
of Advanced Materials, Im Neuenheimer Feld 225, Ruprecht-Karls-Universität, Heidelberg D-69120, Germany
| | - Tiago Buckup
- Physikalisch-Chemisches
Institut, Im Neuenheimer
Feld 229, ‡Organisch-Chemisches Institut, Im Neuenheimer Feld 270, and §Centre
of Advanced Materials, Im Neuenheimer Feld 225, Ruprecht-Karls-Universität, Heidelberg D-69120, Germany
| | - Fabian Paulus
- Physikalisch-Chemisches
Institut, Im Neuenheimer
Feld 229, ‡Organisch-Chemisches Institut, Im Neuenheimer Feld 270, and §Centre
of Advanced Materials, Im Neuenheimer Feld 225, Ruprecht-Karls-Universität, Heidelberg D-69120, Germany
| | - Jens U. Engelhart
- Physikalisch-Chemisches
Institut, Im Neuenheimer
Feld 229, ‡Organisch-Chemisches Institut, Im Neuenheimer Feld 270, and §Centre
of Advanced Materials, Im Neuenheimer Feld 225, Ruprecht-Karls-Universität, Heidelberg D-69120, Germany
| | - Uwe H. F. Bunz
- Physikalisch-Chemisches
Institut, Im Neuenheimer
Feld 229, ‡Organisch-Chemisches Institut, Im Neuenheimer Feld 270, and §Centre
of Advanced Materials, Im Neuenheimer Feld 225, Ruprecht-Karls-Universität, Heidelberg D-69120, Germany
| | - Marcus Motzkus
- Physikalisch-Chemisches
Institut, Im Neuenheimer
Feld 229, ‡Organisch-Chemisches Institut, Im Neuenheimer Feld 270, and §Centre
of Advanced Materials, Im Neuenheimer Feld 225, Ruprecht-Karls-Universität, Heidelberg D-69120, Germany
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130
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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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131
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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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132
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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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133
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Pensack RD, Tilley AJ, Parkin SR, Lee TS, Payne MM, Gao D, Jahnke AA, Oblinsky DG, Li PF, Anthony JE, Seferos DS, Scholes GD. Exciton Delocalization Drives Rapid Singlet Fission in Nanoparticles of Acene Derivatives. J Am Chem Soc 2015; 137:6790-803. [DOI: 10.1021/ja512668r] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Ryan D. Pensack
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Andrew J. Tilley
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Sean R. Parkin
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Tia S. Lee
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Marcia M. Payne
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Dong Gao
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Ashlee A. Jahnke
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Daniel G. Oblinsky
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Peng-Fei Li
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - John E. Anthony
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Dwight S. Seferos
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Gregory D. Scholes
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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134
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Berkelbach TC, Hybertsen MS, Reichman DR. Microscopic theory of singlet exciton fission. III. Crystalline pentacene. J Chem Phys 2015; 141:074705. [PMID: 25149804 DOI: 10.1063/1.4892793] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We extend our previous work on singlet exciton fission in isolated dimers to the case of crystalline materials, focusing on pentacene as a canonical and concrete example. We discuss the proper interpretation of the character of low-lying excited states of relevance to singlet fission. In particular, we consider a variety of metrics for measuring charge-transfer character, conclusively demonstrating significant charge-transfer character in the low-lying excited states. The impact of this electronic structure on the subsequent singlet fission dynamics is assessed by performing real-time master-equation calculations involving hundreds of quantum states. We make direct comparisons with experimental absorption spectra and singlet fission rates, finding good quantitative agreement in both cases, and we discuss the mechanistic distinctions that exist between small isolated aggregates and bulk systems.
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Affiliation(s)
- Timothy C Berkelbach
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - Mark S Hybertsen
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - David R Reichman
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
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135
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Casanova D. Bright Fission: Singlet Fission into a Pair of Emitting States. J Chem Theory Comput 2015; 11:2642-50. [DOI: 10.1021/acs.jctc.5b00144] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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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136
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Brazard J, Bizimana LA, Turner DB. Accurate convergence of transient-absorption spectra using pulsed lasers. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:053106. [PMID: 26026513 DOI: 10.1063/1.4921479] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Transient-absorption spectroscopy is a common and well-developed technique for measuring time-dependent optical phenomena. One important aspect, especially for measurements using pulsed lasers, is how to average multiple data acquisition events. Here, we use a mathematical analysis method based on covariance to evaluate various averaging schemes. The analysis reveals that the baseline and the signal converge to incorrect values without balanced detection of the probe, shot-by-shot detection, and a specific method of averaging. Experiments performed with sub-7 fs pulses confirm the analytic results and reveal insights into molecular excited-state vibrational dynamics.
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Affiliation(s)
- Johanna Brazard
- Department of Chemistry, New York University, New York, New York 10003, USA
| | - Laurie A Bizimana
- Department of Chemistry, New York University, New York, New York 10003, USA
| | - Daniel B Turner
- Department of Chemistry, New York University, New York, New York 10003, USA
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137
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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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138
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Varnavski O, Abeyasinghe N, Aragó J, Serrano-Pérez JJ, Ortí E, López Navarrete JT, Takimiya K, Casanova D, Casado J, Goodson T. High Yield Ultrafast Intramolecular Singlet Exciton Fission in a Quinoidal Bithiophene. J Phys Chem Lett 2015; 6:1375-84. [PMID: 26263138 DOI: 10.1021/acs.jpclett.5b00198] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We report the process of singlet exciton fission with high-yield upon photoexcitation of a quinoidal thiophene molecule. Efficient ultrafast triplet photogeneration and its yield are determined by photoinduced triplet-triplet absorption, flash photolysis triplet lifetime measurements, as well as by femtosecond time-resolved transient absorption and fluorescence methods. These experiments show that optically excited quinoidal bithiophene molecule undergoes ultrafast formation of the triplet-like state with the lifetime ∼57 μs. CASPT2 and RAS-SF calculations have been performed to support the experimental findings. To date, high singlet fission rates have been reported for crystalline and polycrystalline materials, whereas for covalently linked dimers and small oligomers it was found to be relatively small. In this contribution, we show an unprecedented quantum yield of intramolecular singlet exciton fission of ∼180% for a quinoidal bithiophene system.
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Affiliation(s)
- Oleg Varnavski
- †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Neranga Abeyasinghe
- †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Juan Aragó
- ‡Instituto de Ciencia Molecular, Universidad de Valencia, 46980 Paterna, Spain
| | | | - Enrique Ortí
- ‡Instituto de Ciencia Molecular, Universidad de Valencia, 46980 Paterna, Spain
| | | | - Kazuo Takimiya
- ∥Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
| | - David Casanova
- ⊥IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
- ∇Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, 20080 Donostia, Spain
- ¶Donostia International Physics Center (DIPC), 20018 Donostia, Spain
| | - Juan Casado
- §Department of Physical Chemistry, University of Malaga, 29071 Malaga, Spain
| | - Theodore Goodson
- †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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139
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Musser AJ, Maiuri M, Brida D, Cerullo G, Friend RH, Clark J. The nature of singlet exciton fission in carotenoid aggregates. J Am Chem Soc 2015; 137:5130-9. [PMID: 25825939 PMCID: PMC4440407 DOI: 10.1021/jacs.5b01130] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Singlet exciton fission allows the fast and efficient generation of two spin triplet states from one photoexcited singlet. It has the potential to improve organic photovoltaics, enabling efficient coupling to the blue to ultraviolet region of the solar spectrum to capture the energy generally lost as waste heat. However, many questions remain about the underlying fission mechanism. The relation between intermolecular geometry and singlet fission rate and yield is poorly understood and remains one of the most significant barriers to the design of new singlet fission sensitizers. Here we explore the structure-property relationship and examine the mechanism of singlet fission in aggregates of astaxanthin, a small polyene. We isolate five distinct supramolecular structures of astaxanthin generated through self-assembly in solution. Each is capable of undergoing intermolecular singlet fission, with rates of triplet generation and annihilation that can be correlated with intermolecular coupling strength. In contrast with the conventional model of singlet fission in linear molecules, we demonstrate that no intermediate states are involved in the triplet formation: instead, singlet fission occurs directly from the initial 1B(u) photoexcited state on ultrafast time scales. This result demands a re-evaluation of current theories of polyene photophysics and highlights the robustness of carotenoid singlet fission.
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Affiliation(s)
- Andrew J Musser
- †Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - Margherita Maiuri
- ‡IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, I-20133 Milano, Italy
| | - Daniele Brida
- §Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - Giulio Cerullo
- ‡IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, I-20133 Milano, Italy
| | - Richard H Friend
- †Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - Jenny Clark
- ∥Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
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140
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Strong SE, Eaves JD. Tetracene Aggregation on Polar and Nonpolar Surfaces: Implications for Singlet Fission. J Phys Chem Lett 2015; 6:1209-1215. [PMID: 26262973 DOI: 10.1021/acs.jpclett.5b00141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In molecular crystals that exhibit singlet fission, quantum yields depend strongly on intermolecular configurations that control the relevant electronic couplings. Here, we explore how noncovalent interactions between molecules and surfaces stabilize intermolecular structures with strong singlet fission couplings. Using molecular dynamics simulations, we studied the aggregation patterns of tetracene molecules on a solid surface as a function of surface polarity. Even at low surface concentrations, tetracene self-assembled into nanocrystallites where about 10-20% of the clustered molecules were part of at least one herringbone structure. The herringbone structure is the native structure of crystalline tetracene, which exhibits a high singlet fission quantum yield. Increasing the polarity of the surface reduced both the amount of clustering and the relative number of herringbone configurations, but only when the dipoles on the surface were orientationally disordered. These results have implications for the application of singlet fission in dye-sensitized solar cells.
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Affiliation(s)
- Steven E Strong
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Joel D Eaves
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
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141
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Busby E, Xia J, Wu Q, Low JZ, Song R, Miller JR, Zhu XY, Campos LM, Sfeir MY. A design strategy for intramolecular singlet fission mediated by charge-transfer states in donor-acceptor organic materials. NATURE MATERIALS 2015; 14:426-33. [PMID: 25581625 DOI: 10.1038/nmat4175] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 11/18/2014] [Indexed: 05/21/2023]
Abstract
The ability to advance our understanding of multiple exciton generation (MEG) in organic materials has been restricted by the limited number of materials capable of singlet fission. A particular challenge is the development of materials that undergo efficient intramolecular fission, such that local order and strong nearest-neighbour coupling is no longer a design constraint. Here we address these challenges by demonstrating that strong intrachain donor-acceptor interactions are a key design feature for organic materials capable of intramolecular singlet fission. By conjugating strong-acceptor and strong-donor building blocks, small molecules and polymers with charge-transfer states that mediate population transfer between singlet excitons and triplet excitons are synthesized. Using transient optical techniques, we show that triplet populations can be generated with yields up to 170%. These guidelines are widely applicable to similar families of polymers and small molecules, and can lead to the development of new fission-capable materials with tunable electronic structure, as well as a deeper fundamental understanding of MEG.
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Affiliation(s)
- Erik Busby
- 1] Energy Frontier Research Center, Columbia University, New York, New York 10027, USA [2] Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Jianlong Xia
- 1] Energy Frontier Research Center, Columbia University, New York, New York 10027, USA [2] Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Qin Wu
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Jonathan Z Low
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Rui Song
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - John R Miller
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X-Y Zhu
- 1] Energy Frontier Research Center, Columbia University, New York, New York 10027, USA [2] Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Luis M Campos
- 1] Energy Frontier Research Center, Columbia University, New York, New York 10027, USA [2] Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Matthew Y Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
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142
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Renaud N, Grozema FC. Intermolecular Vibrational Modes Speed Up Singlet Fission in Perylenediimide Crystals. J Phys Chem Lett 2015; 6:360-5. [PMID: 26261948 DOI: 10.1021/jz5023575] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report numerical simulations based on a non-Markovian density matrix propagation scheme of singlet fission (SF) in molecular crystals. Ab initio electronic structure calculations were used to parametrize the exciton and phonon Hamiltonian as well as the interactions between the exciton and the intramolecular and intermolecular vibrational modes. We demonstrate that the interactions of the exciton with intermolecular vibrational modes are highly sensitive to the stacking geometry of the crystal and can, in certain cases, significantly accelerate SF. This result may help in understanding the fast SF experimentally observed in a broad range of molecular crystals and offers a new direction for the engineering of efficient SF sensitizers.
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Affiliation(s)
- Nicolas Renaud
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2629BL Delft, The Netherlands
| | - Ferdinand C Grozema
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2629BL Delft, The Netherlands
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143
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Schrauben JN, Zhao Y, Mercado C, Dron PI, Ryerson JL, Michl J, Zhu K, Johnson JC. Photocurrent enhanced by singlet fission in a dye-sensitized solar cell. ACS APPLIED MATERIALS & INTERFACES 2015; 7:2286-2293. [PMID: 25607825 DOI: 10.1021/am506329v] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Investigations of singlet fission have accelerated recently because of its potential utility in solar photoconversion, although only a few reports definitively identify the role of singlet fission in a complete solar cell. Evidence of the influence of singlet fission in a dye-sensitized solar cell using 1,3-diphenylisobenzofuran (DPIBF, 1) as the sensitizer is reported here. Self-assembly of the blue-absorbing 1 with co-adsorbed oxidation products on mesoporous TiO2 yields a cell with a peak internal quantum efficiency of ∼70% and a power conversion efficiency of ∼1.1%. Introducing a ZrO2 spacer layer of thickness varying from 2 to 20 Å modulates the short-circuit photocurrent such that it is initially reduced as thickness increases but 1 with 10-15 Å of added ZrO2. This rise can be explained as being due to a reduced rate of injection of electrons from the S1 state of 1 such that singlet fission, known to occur with a 30 ps time constant in polycrystalline films, has the opportunity to proceed efficiently and produce two T1 states per absorbed photon that can subsequently inject electrons into TiO2. Transient spectroscopy and kinetic simulations confirm this novel mode of dye-sensitized solar cell operation and its potential utility for enhanced solar photoconversion.
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Affiliation(s)
- Joel N Schrauben
- National Renewable Energy Laboratory , 15013 Denver West Parkway, Golden, Colorado 80401, United States
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144
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Abstract
Singlet fission, the splitting of a singlet exciton into two triplet excitons in molecular materials, is interesting not only as a model many-electron problem, but also as a process with potential applications in solar energy conversion. Here we discuss limitations of the conventional four-electron and molecular dimer model in describing singlet fission in crystalline organic semiconductors, such as pentacene and tetracene. We emphasize the need to consider electronic delocalization, which is responsible for the decisive role played by the Mott-Wannier exciton, also called the charge transfer (CT) exciton, in mediating singlet fission. At the strong electronic coupling limit, the initial excitation creates a quantum superposition of singlet, CT, and triplet-pair states, and we present experimental evidence for this interpretation. We also discuss the most recent attempts at translating this mechanistic understanding into design principles for CT state-mediated intramolecular singlet fission in oligomers and polymers.
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Affiliation(s)
- N Monahan
- Department of Chemistry, Columbia University, New York, New York 10027;
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145
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Alguire EC, Subotnik JE, Damrauer NH. Exploring Non-Condon Effects in a Covalent Tetracene Dimer: How Important Are Vibrations in Determining the Electronic Coupling for Singlet Fission? J Phys Chem A 2014; 119:299-311. [DOI: 10.1021/jp510777c] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Ethan C. Alguire
- Department
of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Joseph E. Subotnik
- Department
of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Niels H. Damrauer
- Department
of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, United States
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146
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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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147
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Wilson MWB, Rao A, Johnson K, Gélinas S, di Pietro R, Clark J, Friend RH. Temperature-independent singlet exciton fission in tetracene. J Am Chem Soc 2014; 135:16680-8. [PMID: 24148017 DOI: 10.1021/ja408854u] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We use transient absorption spectroscopy to demonstrate that the dynamics of singlet exciton fission in tetracene are independent of temperature (10–270 K). Low-intensity, broad-band measurements allow the identification of spectral features while minimizing bimolecular recombination. Hence, by directly observing both species, we find that the time constant for the conversion of singlets to triplet pairs is ~90 ps. However, in contrast to pentacene, where fission is effectively unidirectional, we confirm that the emissive singlet in tetracene is readily regenerated from spin-correlated "geminate" triplets following fission, leading to equilibrium dynamics. Although free triplets are efficiently generated at room temperature, the interplay of superradiance and frustrated triplet diffusion contributes to a nearly 20-fold increase in the steady-state fluorescence as the sample is cooled. Together, these results require that singlets and triplet pairs in tetracene are effectively degenerate in energy, and begin to reconcile the temperature dependence of many macroscopic observables with a fission process which does not require thermal activation.
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148
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Wu Y, Liu K, Liu H, Zhang Y, Zhang H, Yao J, Fu H. Impact of Intermolecular Distance on Singlet Fission in a Series of TIPS Pentacene Compounds. J Phys Chem Lett 2014; 5:3451-3455. [PMID: 26278592 DOI: 10.1021/jz5017729] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Singlet fission has attracted considerable interest for its potential application in organic photovoltaics. However, the underlying microscopic mechanism is not well understood and the molecular parameters that govern SF efficiency remain unclear. We herein study the primary exciton photogeneration and evolution in the thin film of a series of pentacene derivatives (TIPS-Pn and ADPD-Pn) using femtosecond transient absorption spectroscopy. With a favorable "long-edge on" packing motif, the singlet-excited slip-stacked TIPS-Pn and ADPD-Pn molecules undergo ultrafast fission to produce triplet excitonic states with time constants of ∼0.3 ps. More importantly, the ADPD-Pn compound features a considerably higher triplet yield than TIPS-Pn (162 ± 10% vs 114 ± 15%). The enhanced electronic coupling as a result of closer interchromophore distance (3.33 Å for ADPD-Pn vs 3.40 Å for TIPS-Pn) is suggested to account for the much higher triplet yield for ADPD-Pn relative to that for TIPS-Pn, proving SF can be readily modulated by adjusting the intermolecular distance.
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Affiliation(s)
- Yishi Wu
- †Beijing National Laboratory for Molecules Science (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Ke Liu
- ‡State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Huiying Liu
- †Beijing National Laboratory for Molecules Science (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yi Zhang
- †Beijing National Laboratory for Molecules Science (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Haoli Zhang
- ‡State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Jiannian Yao
- †Beijing National Laboratory for Molecules Science (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Hongbing Fu
- †Beijing National Laboratory for Molecules Science (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- §Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Capital Normal University, Beijing 100048, People's Republic of China
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149
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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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150
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Zeng T, Ananth N, Hoffmann R. Seeking small molecules for singlet fission: a heteroatom substitution strategy. J Am Chem Soc 2014; 136:12638-47. [PMID: 25140824 DOI: 10.1021/ja505275m] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We design theoretically small molecule candidates for singlet fission chromophores, aiming to achieve a balance between sufficient diradical character and kinetic persistence. We develop a perturbation strategy based on the captodative effect to introduce diradical character into small π-systems. Specifically, this can be accomplished by replacing pairs of not necessarily adjacent C atoms with isoelectronic and isosteric pairs of B and N atoms. Three rules of thumb emerge from our studies to aid further design: (i) Lewis structures provide insight into likely diradical character; (ii) formal radical centers of the diradical must be well-separated; (iii) stabilization of radical centers by a donor (N) and an acceptor (B) is essential. Following the rules, we propose candidate molecules. Employing reliable multireference calculations for excited states, we identify three likely candidate molecules for SF chromophores. These include a benzene, a napthalene, and an azulene, where four C atoms are replaced by a pair of B and a pair of N atoms.
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Affiliation(s)
- Tao Zeng
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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