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Wen J, Ma H. A fragmentation-based approach for evaluating the intra-chain excitonic couplings in conjugated polymers. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.04.099] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Wiebeler C, Plasser F, Hedley GJ, Ruseckas A, Samuel IDW, Schumacher S. Ultrafast Electronic Energy Transfer in an Orthogonal Molecular Dyad. J Phys Chem Lett 2017; 8:1086-1092. [PMID: 28206765 DOI: 10.1021/acs.jpclett.7b00089] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Understanding electronic energy transfer (EET) is an important ingredient in the development of artificial photosynthetic systems and photovoltaic technologies. Although EET is at the heart of these applications and crucially influences their light-harvesting efficiency, the nature of EET over short distances for covalently bound donor and acceptor units is often not well understood. Here we investigate EET in an orthogonal molecular dyad (BODT4), in which simple models fail to explain the very origin of EET. On the basis of nonadiabatic ab initio molecular dynamics calculations and ultrafast fluorescence experiments, we gain detailed microscopic insights into the ultrafast electrovibrational dynamics following photoexcitation. Our analysis offers molecular-level insights into these processes and reveals that it takes place on time scales ≲100 fs and occurs through an intermediate charge-transfer state.
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Affiliation(s)
- Christian Wiebeler
- Physics Department and Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn , Warburger Strasse 100, 33098 Paderborn, Germany
| | - Felix Plasser
- Institute for Theoretical Chemistry, Faculty of Chemistry, University of Vienna , Währingerstr. 17, 1090 Vienna, Austria
| | - Gordon J Hedley
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Arvydas Ruseckas
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom
| | - Stefan Schumacher
- Physics Department and Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn , Warburger Strasse 100, 33098 Paderborn, Germany
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Wildman J, Repiščák P, Paterson MJ, Galbraith I. General Force-Field Parametrization Scheme for Molecular Dynamics Simulations of Conjugated Materials in Solution. J Chem Theory Comput 2016; 12:3813-24. [PMID: 27397762 PMCID: PMC4980687 DOI: 10.1021/acs.jctc.5b01195] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
We
describe a general scheme to obtain force-field parameters for
classical molecular dynamics simulations of conjugated polymers. We
identify a computationally inexpensive methodology for calculation
of accurate intermonomer dihedral potentials and partial charges.
Our findings indicate that the use of a two-step methodology of geometry
optimization and single-point energy calculations using DFT methods
produces potentials which compare favorably to high level theory calculation.
We also report the effects of varying the conjugated backbone length
and alkyl side-chain lengths on the dihedral profiles and partial
charge distributions and determine the existence of converged lengths
above which convergence is achieved in the force-field parameter sets.
We thus determine which calculations are required for accurate parametrization
and the scope of a given parameter set for variations to a given molecule.
We perform simulations of long oligomers of dioctylfluorene and hexylthiophene
in explicit solvent and find peristence lengths and end-length distributions
consistent with experimental values.
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Affiliation(s)
- Jack Wildman
- Institute for Photonics and Quantum Sciences, School of Engineering and Physical Sciences, SUPA and ‡Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - Peter Repiščák
- Institute for Photonics and Quantum Sciences, School of Engineering and Physical Sciences, SUPA and ‡Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - Martin J Paterson
- Institute for Photonics and Quantum Sciences, School of Engineering and Physical Sciences, SUPA and ‡Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - Ian Galbraith
- Institute for Photonics and Quantum Sciences, School of Engineering and Physical Sciences, SUPA and ‡Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
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Chen CT, Chuang C, Cao J, Ball V, Ruch D, Buehler MJ. Excitonic effects from geometric order and disorder explain broadband optical absorption in eumelanin. Nat Commun 2014; 5:3859. [PMID: 24848640 DOI: 10.1038/ncomms4859] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 04/11/2014] [Indexed: 12/21/2022] Open
Abstract
Eumelanin is a ubiquitous biological pigment, and the origin of its broadband absorption spectrum has long been a topic of scientific debate. Here, we report a first-principles computational investigation to explain its broadband absorption feature. These computations are complemented by experimental results showing a broadening of the absorption spectra of dopamine solutions upon their oxidation. We consider a variety of eumelanin molecular structures supported by experiments or theoretical studies, and calculate the absorption spectra with proper account of the excitonic couplings based on the Frenkel exciton model. The interplay of geometric order and disorder of eumelanin aggregate structures broadens the absorption spectrum and gives rise to a relative enhancement of absorption intensity at the higher-energy end, proportional to the cube of absorption energy. These findings show that the geometric disorder model is as able as the chemical disorder model, and complements this model, to describe the optical properties of eumelanin.
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Affiliation(s)
- Chun-Teh Chen
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-235A&B, Cambridge, Massachusetts 02139, USA
| | - Chern Chuang
- 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
| | - Vincent Ball
- Faculté de Chirurgie Dentaire, Université de Strasbourg, 8 rue Sainte Elizabeth, 67000 Strasbourg, France and Unité INSERM 1121, 11 rue Humann, 67085 Strasbourg Cédex, France
| | - David Ruch
- Department for Advanced Materials and Structures, Centre de Recherche Public Henri Tudor, 5 rue Bommel, L-4940 Hautcharage, Luxembourg
| | - Markus J Buehler
- 1] Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-235A&B, Cambridge, Massachusetts 02139, USA [2] Center for Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA [3] Center for Computational Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Harriman A, Alamiry MAH, Hagon JP, Hablot D, Ziessel R. Through-Space Electronic Energy Transfer Across Proximal Molecular Dyads. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201302081] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Harriman A, Alamiry MAH, Hagon JP, Hablot D, Ziessel R. Through-Space Electronic Energy Transfer Across Proximal Molecular Dyads. Angew Chem Int Ed Engl 2013; 52:6611-5. [DOI: 10.1002/anie.201302081] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Indexed: 11/07/2022]
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