1
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Einsele R, Mitrić R. Nonadiabatic Exciton Dynamics and Energy Gradients in the Framework of FMO-LC-TDDFTB. J Chem Theory Comput 2024. [PMID: 39051619 DOI: 10.1021/acs.jctc.4c00539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
We introduce a novel methodology for simulating the excited-state dynamics of extensive molecular aggregates in the framework of the long-range corrected time-dependent density-functional tight-binding fragment molecular orbital method (FMO-LC-TDDFTB) combined with the mean-field Ehrenfest method. The electronic structure of the system is described in a quasi-diabatic basis composed of locally excited and charge-transfer states of all fragments. In order to carry out nonadiabatic molecular dynamics simulations, we derive and implement the excited-state gradients of the locally excited and charge-transfer states. Subsequently, the accuracy of the analytical excited-state gradients is evaluated. The applicability to the simulation of exciton transport in organic semiconductors is illustrated on a large cluster of anthracene molecules. Additionally, nonadiabatic molecular dynamics simulations of a model system of benzothieno-benzothiophene molecules highlight the method's utility in studying charge-transfer dynamics in organic materials. Our new methodology will facilitate the investigation of excitonic transfer in extensive biological systems, nanomaterials, and other complex molecular systems consisting of thousands of atoms.
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Affiliation(s)
- Richard Einsele
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität, Würzburg 97074, Germany
| | - Roland Mitrić
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität, Würzburg 97074, Germany
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2
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Hino K, Kurashige Y. Encoding a Many-Body Potential Energy Surface into a Grid-Based Matrix Product Operator. J Chem Theory Comput 2024; 20:3839-3849. [PMID: 38647101 DOI: 10.1021/acs.jctc.4c00046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
An efficient algorithm for compressing a given many-body potential energy surface (PES) of molecular systems into a grid-based matrix product operator (MPO) is proposed. The PES is once represented by a full-dimensional or truncated many-body expansion form, which is obtained by ab initio calculations at each grid mesh point, and then all terms in the expansion are compressed and merged into a single MPO while maintaining the bond dimension of the MPO as small as possible. It was shown that the ab initio PES of the H2CO was compressed by more than 2 orders of magnitude in the size of the site operators without loss of accuracy. By the use of grid basis, the tensor rank of the site operators of the MPO is reduced from four to three due to the diagonal nature of the position-dependent operators on grid basis, which significantly reduces the computational cost of the tensor contractions required in the real and imaginary time evolution of the matrix product state (MPS) wave functions with the grid-based MPO (Grid-MPO) Hamiltonian. Similar to other grid-based methods, Grid-MPO is easily applicable to any kinds of potentials of molecular systems, such as analytical empirical model potentials expressed by position operators and ab initio potentials, if the values at the grid points are available. Using the Grid-MPO combined with the MPS, we calculated the time correlation function of the Eigen cation H 3 O + ( H 2 O ) 3 to predict the infrared spectrum and compared with the experimental and the previous theoretical studies. The actual scaling with the size of systems was examined for the multidimensional Henon-Heiles Hamiltonian. It was shown that the method is considerably accelerated by the graphic processing unit (GPU) because the sizes of site operators were kept small and all tensors were able to be stored on the VRAM of a GPU.
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Affiliation(s)
- Kentaro Hino
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yuki Kurashige
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
- FOREST, JST, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan
- CREST, JST, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan
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3
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Brey D, Burghardt I. Coherent Transient Localization Mechanism of Interchain Exciton Transport in Regioregular P3HT: A Quantum-Dynamical Study. J Phys Chem Lett 2024; 15:1836-1845. [PMID: 38334949 DOI: 10.1021/acs.jpclett.3c03290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Transient localization has been proposed as a transport mechanism in organic materials, for both charge carriers and excitons. Here, we characterize a quantum coherent transient localization mechanism using full quantum simulations of an H-aggregated model system representative of regioregular poly(3-hexylthiophene) (rrP3HT). A Frenkel-Holstein Hamiltonian parametrized from first principles is considered, including local high-frequency modes and anharmonic, site-correlated interchain modes. Quantum-dynamical calculations are carried out using the Multi-Layer Multi-Configuration Time-Dependent Hartree (ML-MCTDH) method for a 13-site system with 195 vibrational modes, under periodic boundary conditions. It is shown that temporary localization of exciton polarons alternates with resonant transfer driven by interchain modes. While the transport process is mainly determined by exciton-polarons at the low-energy band edge, persistent coupling with the excitonic manifold is observed, giving rise to a nonadiabatic excitonic flux. This elementary transport mechanism remains preserved for limited static disorder and gives way to Anderson localization when the static disorder becomes dominant.
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Affiliation(s)
- Dominik Brey
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Irene Burghardt
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
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4
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Titov E. Visible Light Induced Exciton Dynamics and trans-to- cis Isomerization in Azobenzene Aggregates: Insights from Surface Hopping/Semiempirical Configuration Interaction Molecular Dynamics Simulations. ACS OMEGA 2024; 9:8520-8532. [PMID: 38405525 PMCID: PMC10882624 DOI: 10.1021/acsomega.3c09900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/19/2024] [Accepted: 01/24/2024] [Indexed: 02/27/2024]
Abstract
Assemblies of photochromic molecules feature exciton states, which govern photochemical and photophysical processes in multichromophoric systems. Understanding the photoinduced dynamics of the assemblies requires nonadiabatic treatment involving multiple exciton states and numerous nuclear degrees of freedom, thus posing a challenge for simulations. In this work, we address this challenge for aggregates of azobenzene, a prototypical molecular switch, performing on-the-fly surface hopping calculations combined with semiempirical configuration interaction electronic structure and augmented with transition density matrix analysis to characterize exciton evolution. Specifically, we consider excitation of azobenzene tetramers in the nπ* absorption band located in the visible (blue) part of the electromagnetic spectrum, thus extending our recent work on dynamics after ππ* excitation corresponding to the ultraviolet region [Titov, J. Phys. Chem. C2023, 127, 13678-13688]. We find that the nπ* excitons, which are initially strongly localized by ground-state conformational disorder, undergo further (very strong) localization during short-time photodynamics. This excited-state localization process is extremely ultrafast, occurring within the first 10 fs of photodynamics. We observe virtually no exciton transfer of the localized excitons in the nπ* manifold. However, the transfer may occur via secondary pathways involving ππ* states or the ground state. Moreover, we find that the nπ* quantum yields of the trans-to-cis isomerization are reduced in the aggregated state.
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Affiliation(s)
- Evgenii Titov
- Institute of Chemistry, Theoretical
Chemistry, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
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5
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Iyengar SS, Zhang JH, Saha D, Ricard TC. Graph-| Q⟩⟨ C|: A Quantum Algorithm with Reduced Quantum Circuit Depth for Electronic Structure. J Phys Chem A 2023; 127:9334-9345. [PMID: 37906738 DOI: 10.1021/acs.jpca.3c04261] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
The accurate determination of chemical properties is known to have a critical impact on multiple fundamental chemical problems but is deeply hindered by the steep algebraic scaling of electron correlation calculations and the exponential scaling of quantum nuclear dynamics. With the advent of new quantum computing hardware and associated developments in creating new paradigms for quantum software, this avenue has been recognized as perhaps one way to address exponentially complex challenges in quantum chemistry and molecular dynamics. In this paper, we discuss a new approach to drastically reduce the quantum circuit depth (by several orders of magnitude) and help improve the accuracy in the quantum computation of electron correlation energies for large molecular systems. The method is derived from a graph-theoretic approach to molecular fragmentation and enables us to create a family of projection operators that decompose quantum circuits into separate unitary processes. Some of these processes can be treated on quantum hardware and others on classical hardware in a completely asynchronous and parallel fashion. Numerical benchmarks are provided through the computation of unitary coupled-cluster singles and doubles (UCCSD) energies for medium-sized protonated and neutral water clusters using the new quantum algorithms presented here.
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Affiliation(s)
- Srinivasan S Iyengar
- Department of Chemistry, Department of Physics, and the Indiana University Quantum Science and Engineering Center (IU-QSEC), Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Juncheng Harry Zhang
- Department of Chemistry, Department of Physics, and the Indiana University Quantum Science and Engineering Center (IU-QSEC), Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Debadrita Saha
- Department of Chemistry, Department of Physics, and the Indiana University Quantum Science and Engineering Center (IU-QSEC), Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Timothy C Ricard
- Department of Chemistry, Department of Physics, and the Indiana University Quantum Science and Engineering Center (IU-QSEC), Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
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6
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Palacino-González E, Jansen TLC. Modeling the Effect of Disorder in the Two-Dimensional Electronic Spectroscopy of Poly-3-hexyltiophene in an Organic Photovoltaic Blend: A Combined Quantum/Classical Approach. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:6793-6801. [PMID: 37081993 PMCID: PMC10108354 DOI: 10.1021/acs.jpcc.3c01080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 02/28/2023] [Indexed: 05/03/2023]
Abstract
We introduce a first-principles model of the 12-mer poly-3-hexyltiophene (P3HT) polymer system in the realistic description of an organic photovoltaic blend environment. We combine Molecular Dynamics (MD) simulations of a thin-film blend of P3HT and phenyl-C61-butyric acid methyl ester (PCBM) to model the interactions with a fluctuating environment with Time-Dependent Density Functional Theory (TDDFT) calculations to parametrize the effect of the torsional flexibility in the polymer and construct an exciton-type Hamiltonian that describes the photoexcitation of the polymer. This allows us to reveal the presence of different flexibility patterns governed by the torsional angles along the polymer chain which, in the interacting fluctuating environment, control the broadening of the spectral observables. We identify the origin of the homogeneous and inhomogeneous line shape of the simulated optical signals. This is paramount to decipher the spectroscopic nature of the ultrafast electron-transfer process occurring in organic photovoltaic (OPV) materials.
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7
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Balzer D, Kassal I. Mechanism of Delocalization-Enhanced Exciton Transport in Disordered Organic Semiconductors. J Phys Chem Lett 2023; 14:2155-2162. [PMID: 36802583 DOI: 10.1021/acs.jpclett.2c03886] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Large exciton diffusion lengths generally improve the performance of organic semiconductor devices, because they enable energy to be transported farther during the exciton lifetime. However, the physics of exciton motion in disordered organic materials is not fully understood, and modeling the transport of quantum-mechanically delocalized excitons in disordered organic semiconductors is a computational challenge. Here, we describe delocalized kinetic Monte Carlo (dKMC), the first model of three-dimensional exciton transport in organic semiconductors that includes delocalization, disorder, and polaron formation. We find that delocalization can dramatically increase exciton transport; for example, delocalization across less than two molecules in each direction can increase the exciton diffusion coefficient by over an order of magnitude. The mechanism for the enhancement is 2-fold: delocalization enables excitons to hop both more frequently and further in each hop. We also quantify the effect of transient delocalization (short-lived periods where excitons become highly delocalized) and show that it depends strongly upon the disorder and transition dipole moments.
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Affiliation(s)
- Daniel Balzer
- School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Ivan Kassal
- School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
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8
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Fureraj I, Budkina DS, Vauthey E. Torsional disorder and planarization dynamics: 9,10-bis(phenylethynyl)anthracene as a case study. Phys Chem Chem Phys 2022; 24:25979-25989. [PMID: 36263805 PMCID: PMC9627944 DOI: 10.1039/d2cp03909e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/04/2022] [Indexed: 06/14/2023]
Abstract
Conjugated molecules with phenylethynyl building blocks are usually characterised by torsional disorder at room temperature. They are much more rigid in the electronic excited state due to conjugation. As a consequence, the electronic absorption and emission spectra do not present a mirror-image relationship. Here, we investigate how torsional disorder affects the excited state dynamics of 9,10-bis(phenylethynyl)anthracene in solvents of different viscosities and in polymers, using both stationary and ultrafast electronic spectroscopies. Temperature-dependent measurements reveal inhomogeneous broadening of the absorption spectrum at room temperature. This is confirmed by ultrafast spectroscopic measurements at different excitation wavelengths. Red-edge irradiation excites planar molecules that return to the ground state without significant structural dynamics. In this case, however, re-equilibration of the torsional disorder in the ground state can be observed. Higher-energy irradiation excites torsionally disordered molecules, which then planarise, leading to important spectral dynamics. The latter is found to occur partially via viscosity-independent inertial motion, whereas it is purely diffusive in the ground state. This dissimilarity is explained in terms of the steepness of the potential along the torsional coordinate.
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Affiliation(s)
- Ina Fureraj
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
| | - Darya S Budkina
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
| | - Eric Vauthey
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
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9
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Mondelo-Martell M, Brey D, Burghardt I. Quantum dynamical study of inter-chain exciton transport in a regioregular P3HT model system at finite temperature: HJ vs. H-aggregate models. J Chem Phys 2022; 157:094108. [DOI: 10.1063/5.0104729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report on quantum dynamical simulations of inter-chain exciton transport in a model of regioregular poly(3-hexylthiophene), rr-P3HT, at finite temperature, using the Multi-Layer Multi-Configuration Time-Dependent Hartree (ML-MCTDH) method for a system of up to 63 electronic states and 180 vibrational modes. A Frenkel Hamiltonian of HJ aggregate type is used, along with a reduced H-aggregate representation; electron-phonon coupling includes local high-frequency modes as well as anharmonic intermolecular modes. The latter are operative in mediating inter-chain transport, by a mechanism of transient localization type. Strikingly, this mechanism is found to be of quantum coherent character and involves non-adiabatic effects. Using periodic boundary conditions, a normal diffusion regime is identified from the exciton mean-squared displacement, apart from early-time transients. Diffusion coefficients are found to be of the order of 3 x 10-3 cm2/s, showing a non-monotonous increase with temperature.
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Affiliation(s)
- Manel Mondelo-Martell
- Institut für Physikalische u. Theoretische Chemie, Goethe-Universitat Frankfurt am Main Institut fur Physikalische und Theoretische Chemie, Germany
| | | | - Irene Burghardt
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Germany
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10
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Langkabel F, Albrecht PA, Bande A, Krause P. Making Optical Excitations Visible - an Exciton Wavefunction Extension to the Time-dependent Configuration Interaction Method. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111502] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Dilmurat R, Prodhan S, Wang L, Beljonne D. Thermally activated intra-chain charge transport in high charge-carrier mobility copolymers. J Chem Phys 2022; 156:084115. [DOI: 10.1063/5.0082569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Disordered or even seemingly amorphous, donor–acceptor type, conjugated copolymers with high charge-carrier mobility have emerged as a new class of functional materials, where transport along the conjugated backbone is key. Here, we report on non-adiabatic molecular dynamics simulations of charge-carrier transport along chains of poly (indacenodithiophene-co-benzothiadiazole), within a model Hamiltonian parameterized against first-principles calculations. We predict thermally activated charge transport associated with a slightly twisted ground-state conformation, on par with experimental results. Our results also demonstrate that the energy mismatch between the hole on the donor vs the acceptor units of the copolymer drives localization of the charge carriers and limits the intra-chain charge-carrier mobility. We predict that room-temperature mobility values in excess of 10 cm2 V−1 s−1 can be achieved through proper chemical tuning of the component monomer units.
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Affiliation(s)
- Rishat Dilmurat
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc, 20, 7000 Mons, Belgium
| | - Suryoday Prodhan
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc, 20, 7000 Mons, Belgium
| | - Linjun Wang
- Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc, 20, 7000 Mons, Belgium
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12
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Brey D, Binder R, Martinazzo R, Burghardt I. Signatures of coherent vibronic exciton dynamics and conformational control in two-dimensional electronic spectroscopy of conjugated polymers. Faraday Discuss 2022; 237:148-167. [DOI: 10.1039/d2fd00014h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two-dimensional electronic spectroscopy (2DES) signals for homo-oligomer J-aggregates are computed, with a focus on the role of structural change induced by low-frequency torsional modes along with quasi-stationary trapping effects induced...
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13
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Titov E, Kopp T, Hoche J, Humeniuk A, Mitrić R. (De)localization dynamics of molecular excitons: comparison of mixed quantum–classical and fully quantum treatments. Phys Chem Chem Phys 2022; 24:12136-12148. [DOI: 10.1039/d2cp00586g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular excitons play a central role in processes of solar energy conversion, both natural and artificial. It is therefore no wonder that numerous experimental and theoretical investigations in the last...
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14
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Krause P, Tremblay JC, Bande A. Atomistic Simulations of Laser-Controlled Exciton Transfer and Stabilization in Symmetric Double Quantum Dots. J Phys Chem A 2021; 125:4793-4804. [PMID: 34047560 DOI: 10.1021/acs.jpca.1c02501] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The creation, transfer, and stabilization of localized excitations are studied in a donor-acceptor Frenkel exciton model in an atomistic treatment of reduced-size double quantum dots (QDs) of various sizes. The explicit time-dependent dynamics simulations carried out by hybrid time-dependent density functional theory/configuration interaction show that laser-controlled hole trapping in stacked, coupled germanium/silicon quantum dots can be achieved by a UV/IR pump-dump pulse sequence. The first UV excitation creates an exciton localized on the topmost QD and after some coherent transfer time, an IR pulse dumps and localizes an exciton in the bottom QD. While hole trapping is observed in each excitation step, we show that the stability of the localized electron depends on its multiexcitonic character. We present how size and geometry variations of three Ge/Si nanocrystals influence transfer times and thus the efficiency of laser-driven populations of the electron-hole pair states.
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Affiliation(s)
- Pascal Krause
- Theory of Electron Dynamics and Spectroscopy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner Platz 1, 14109 Berlin, Germany.,Physical and Theoretical Chemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Jean Christophe Tremblay
- Laboratoire de Physique et Chimie Théoriques, UMR7019, CNRS-Université de Lorraine, 1 Bd Arago, 57070 Metz, France
| | - Annika Bande
- Theory of Electron Dynamics and Spectroscopy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner Platz 1, 14109 Berlin, Germany
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15
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Popp W, Brey D, Binder R, Burghardt I. Quantum Dynamics of Exciton Transport and Dissociation in Multichromophoric Systems. Annu Rev Phys Chem 2021; 72:591-616. [PMID: 33636997 DOI: 10.1146/annurev-physchem-090419-040306] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Due to the subtle interplay of site-to-site electronic couplings, exciton delocalization, nonadiabatic effects, and vibronic couplings, quantum dynamical studies are needed to elucidate the details of ultrafast photoinduced energy and charge transfer events in organic multichromophoric systems. In this vein, we review an approach that combines first-principles parameterized lattice Hamiltonians with accurate quantum dynamical simulations using advanced multiconfigurational methods. Focusing on the elementary transfer steps in organic functional materials, we address coherent exciton migration and creation of charge transfer excitons in homopolymers, notably representative of the poly(3-hexylthiophene) material, as well as exciton dissociation at polymer:fullerene heterojunctions. We emphasize the role of coherent transfer, trapping effects due to high-frequency phonon modes, and thermal activation due to low-frequency soft modes that drive a diffusive dynamics.
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Affiliation(s)
- Wjatscheslaw Popp
- Institute for Physical and Theoretical Chemistry, Goethe University Frankfurt, 60438 Frankfurt, Germany;
| | - Dominik Brey
- Institute for Physical and Theoretical Chemistry, Goethe University Frankfurt, 60438 Frankfurt, Germany;
| | - Robert Binder
- Institute for Physical and Theoretical Chemistry, Goethe University Frankfurt, 60438 Frankfurt, Germany;
| | - Irene Burghardt
- Institute for Physical and Theoretical Chemistry, Goethe University Frankfurt, 60438 Frankfurt, Germany;
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16
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Di Maiolo F, Brey D, Binder R, Burghardt I. Quantum dynamical simulations of intra-chain exciton diffusion in an oligo (para-phenylene vinylene) chain at finite temperature. J Chem Phys 2020; 153:184107. [PMID: 33187420 DOI: 10.1063/5.0027588] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
We report on quantum dynamical simulations of exciton diffusion in an oligo(para-phenylene vinylene) chain segment with 20 repeat units (OPV-20) at finite temperature, complementary to our recent study of the same system at T = 0 K [R. Binder and I. Burghardt, J. Chem. Phys. 152, 204120 (2020)]. Accurate quantum dynamical simulations are performed using the multi-layer multi-configuration time-dependent Hartree method as applied to a site-based Hamiltonian comprising 20 electronic states of Frenkel type and 460 vibrational modes, including site-local quinoid-distortion modes along with site-correlated bond-length alternation (BLA) modes, ring torsional modes, and an explicit harmonic-oscillator bath. A first-principles parameterized Frenkel-Holstein type Hamiltonian is employed, which accounts for correlations between the ring torsional modes and the anharmonically coupled BLA coordinates located at the same junction. Thermally induced fluctuations of the torsional modes are described by a stochastic mean-field approach, and their impact on the excitonic motion is characterized in terms of the exciton mean-squared displacement. A normal diffusion regime is observed under periodic boundary conditions, apart from transient localization features. Even though the polaronic exciton species are comparatively weakly bound, exciton diffusion is found to be a coherent-rather than hopping type-process, driven by the fluctuations of the soft torsional modes. Similar to the previous observations for oligothiophenes, the evolution for the most part exhibits a near-adiabatic dynamics of local exciton ground states (LEGSs) that adjust to the local conformational dynamics. However, a second mechanism, involving resonant transitions between neighboring LEGSs, gains importance at higher temperatures.
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Affiliation(s)
- Francesco Di Maiolo
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
| | - Dominik Brey
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
| | - Robert Binder
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
| | - Irene Burghardt
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
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17
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Hegger R, Binder R, Burghardt I. First-Principles Quantum and Quantum-Classical Simulations of Exciton Diffusion in Semiconducting Polymer Chains at Finite Temperature. J Chem Theory Comput 2020; 16:5441-5455. [PMID: 32786907 DOI: 10.1021/acs.jctc.0c00351] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We report on first-principles quantum-dynamical and quantum-classical simulations of photoinduced exciton dynamics in oligothiophene chain segments, representative of intrachain exciton migration in the poly(3-hexylthiophene) (P3HT) polymer. Following up on our recent study (Binder R.; Burghardt, I. Faraday Discuss. 2020, 221, 406), multilayer multiconfiguration time-dependent Hartree calculations for a short oligothiophene segment comprising 20 monomer units (OT-20) are carried out to obtain full quantum-dynamical simulations at finite temperature. These are employed to benchmark mean-field Ehrenfest calculations, which are shown to give qualitatively correct results for the present system. Periodic boundary conditions turn out to significantly improve earlier estimates of diffusion coefficients. Using the Ehrenfest approach, a series of calculations are subsequently carried out for larger lattices (OT-40 to OT-80), leading to estimates for temperature-dependent mean-squared displacements, which are found to exhibit a near-linear dependence as a function of time. The resulting diffusion coefficient estimates are an increasing function of temperature, whose detailed functional form depends on the degree of static disorder. With a realistic static disorder parameter (σs ≃ 0.06 eV), the diffusion coefficients decrease from D ∼ 1 × 10-2 cm2 s-1 to D ∼ 1 × 10-3 cm2 s-1, in qualitative agreement with experimental data for P3HT. The dynamical scenario obtained from our simulations shows that exciton migration in P3HT-type chains is a largely adiabatic process throughout the temperature regime we investigated (i.e., T = 50-300 K). The resulting picture of exciton migration is a coherent, but not bandlike, motion of an exciton-polaron driven by fluctuations induced by low-frequency modes. This process acquires partial hopping character if static disorder becomes prominent and Anderson localization sets in.
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Affiliation(s)
- Rainer Hegger
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
| | - Robert Binder
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
| | - Irene Burghardt
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
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Prodhan S, Qiu J, Ricci M, Roscioni OM, Wang L, Beljonne D. Design Rules to Maximize Charge-Carrier Mobility along Conjugated Polymer Chains. J Phys Chem Lett 2020; 11:6519-6525. [PMID: 32692920 DOI: 10.1021/acs.jpclett.0c01793] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The emergence of polymeric materials displaying high charge-carrier mobility values despite poor interchain structural order has spawned a renewal of interest in the identification of structure-property relationships pertaining to the transport of charges along conjugated polymer chains and the subsequent design of optimized architectures. Here, we present the results of intrachain charge transport simulations obtained by applying a robust surface hopping algorithm to a phenomenological Hamiltonian parametrized against first-principles simulations. Conformational effects are shown to provide a clear signature in the temperature-dependent charge-carrier mobility that complies with recent experimental observations. We further contrast against molecular crystals the evolution with electronic bandwidth and electron-phonon interactions of the room-temperature mobility in polymers, showing that intrachain charge-carrier mobility values in excess of 100 cm2/(V s) can be achieved through a proper chemical engineering of the backbones.
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Affiliation(s)
- Suryoday Prodhan
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons 7000, Belgium
| | - Jing Qiu
- Center for Chemistry of Novel & High-Performance Materials and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | | | | | - Linjun Wang
- Center for Chemistry of Novel & High-Performance Materials and Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons 7000, Belgium
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Binder R, Bonfanti M, Lauvergnat D, Burghardt I. First-principles description of intra-chain exciton migration in an oligo(para-phenylene vinylene) chain. I. Generalized Frenkel-Holstein Hamiltonian. J Chem Phys 2020; 152:204119. [PMID: 32486686 DOI: 10.1063/5.0004510] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A generalized Frenkel-Holstein Hamiltonian is constructed to describe exciton migration in oligo(para-phenylene vinylene) chains, based on excited state electronic structure data for an oligomer comprising 20 monomer units (OPV-20). Time-dependent density functional theory calculations using the ωB97XD hybrid functional are employed in conjunction with a transition density analysis to study the low-lying singlet excitations and demonstrate that these can be characterized to a good approximation as a Frenkel exciton manifold. Based on these findings, we employ the analytic mapping procedure of Binder et al. [J. Chem. Phys. 141, 014101 (2014)] to translate one-dimensional (1D) and two-dimensional (2D) potential energy surface (PES) scans to a fully anharmonic, generalized Frenkel-Holstein (FH) Hamiltonian. A 1D PES scan is carried out for intra-ring quinoid distortion modes, while 2D PES scans are performed for the anharmonically coupled inter-monomer torsional and vinylene bridge bond length alternation modes. The kinetic energy is constructed in curvilinear coordinates by an exact numerical procedure, using the TNUM Fortran code. As a result, a fully molecular-based, generalized FH Hamiltonian is obtained, which is subsequently employed for quantum exciton dynamics simulations, as shown in Paper II [R. Binder and I. Burghardt, J. Chem. Phys. 152, 204120 (2020)].
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Affiliation(s)
- Robert Binder
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
| | - Matteo Bonfanti
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
| | - David Lauvergnat
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France
| | - Irene Burghardt
- Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
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