1
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Haghshenas H, Spano FC. Impact of Local and Nonlocal Vibronic Coupling on the Absorption and Emission Spectra of J- and H-Dimers. J Chem Theory Comput 2024; 20:4790-4803. [PMID: 38768310 DOI: 10.1021/acs.jctc.4c00299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
The impact of exciton-vibrational (EV) coupling involving low-energy ("slow") intermolecular vibrations and higher-energy ("fast") intramolecular vibrations on the absorption and emission spectra of H- and J-dimers is studied theoretically for a pair of chromophores with excitonic coupling dominated by transition dipole-dipole coupling, JC. Exact quantum-mechanical solutions based on a Frenkel-Holstein-Peierls Hamiltonian reveal a fascinating interplay between the two coupling sources in determining the spectral line widths, Stoke shifts and radiative decay rates. It is shown that the ratio rules derived from the vibronic progression of the fast mode in molecular dimers remain valid under the influence of slow-mode EV coupling under most conditions. However, a highly unusual aggregate behavior occurs when the product of local and nonlocal couplings, |gLgNL|, exceeds 2ℏωs|JC|, where ℏωs is the energy of the slow mode. In this regime and when gL and gNL are in-phase, an H-dimer (JC > 0) becomes strongly emissive and can even be super-radiant, while a J-dimer (JC < 0) with out-of-phase gL and gNL values becomes subradiant. Such behaviors are in marked contrast to the predictions of Kasha theory and demonstrate the richness of the photophysical behavior resulting from EV coupling involving inter- and intramolecular vibrations.
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Affiliation(s)
- Hamed Haghshenas
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Frank C Spano
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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2
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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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3
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Schötz K, Panzer F, Sommer M, Bässler H, Köhler A. A spectroscopic assessment of static and dynamic disorder in a film of a polythiophene with a planarized backbone. MATERIALS HORIZONS 2023; 10:5538-5546. [PMID: 37853812 DOI: 10.1039/d3mh01262j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
The optoelectronic performance of organic semiconductor devices is related to the static and dynamic disorder in the film. The disorder can be assessed by considering the linewidth of its optical spectra. We focus on identifying the effect of conjugation length distribution on the static energetic disorder. Hence, we disentangle the contributions of static and dynamic disorder to the absorption and emission spectra of poly(3-(2,5-dioctylphenyl)-thiophene) (PDOPT) by exploring how the linewidth and energy of the spectra evolve upon cooling the sample from 300 K to 5 K. PDOPT has sterically hindered side chains that arrange such as to cause a planarized polymer backbone. This makes it a suitable model for a quasi-one-dimensional molecular system. By modelling the conjugated segments as coupled oscillators we find that the linewidth contribution resulting from the variation of conjugation length decreases linearly with decreasing exciton energy and extrapolates to zero at the energy corresponding to an infinite chain. These results provide a new avenue to the design of low disorder and hence high mobility polymeric semiconductors.
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Affiliation(s)
- Konstantin Schötz
- Soft Matter Optoelectronics and Bavarian Polymer Institute (BPI), University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Fabian Panzer
- Soft Matter Optoelectronics and Bavarian Polymer Institute (BPI), University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Michael Sommer
- Institute for Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany
| | - Heinz Bässler
- Bayreuth Institute of Macromolecular Research (BIMF), University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.
| | - Anna Köhler
- Soft Matter Optoelectronics and Bavarian Polymer Institute (BPI), University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
- Bayreuth Institute of Macromolecular Research (BIMF), University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.
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4
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Minion L, Wade J, Moreno‐Naranjo JM, Ryan S, Siligardi G, Fuchter MJ. Insights into the origins of inverted circular dichroism in thin films of a chiral side chain polyfluorene. Chirality 2023; 35:817-825. [PMID: 37349263 PMCID: PMC10946986 DOI: 10.1002/chir.23601] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/16/2023] [Accepted: 06/05/2023] [Indexed: 06/24/2023]
Abstract
We synthesized a fluorene-bithiophene co-polymer with chiral side chains (cPFT2) and investigated its chiroptical properties via synchotronradiation circular dichroism. We observed that thin films of the polymer display an intense circular dichroism (CD) upon annealing, which is of opposite handedness to the CD reported for similar polyfluorenes bearing the same enantiomeric chiral side chain. We then contrast the properties of this polymer with chiral side chain fluorene homopolymer (cPF) and observe large differences in their thin film morphology. Using photoluminescence spectroscopy, we uncover evidence of polymer chain bending in cPFT2, which is further supported by theoretical calculations, and propose an explanation for the observed inverted optical activity.
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Affiliation(s)
- Louis Minion
- Department of MaterialsImperial College LondonLondonUK
- Centre for Processable ElectronicsImperial College London, South Kensington CampusLondonUK
- B23 Beamline, Diamond Light Source Ltd, Harwell Science and Innovation CampusDidcotUK
| | - Jessica Wade
- Department of MaterialsImperial College LondonLondonUK
- Centre for Processable ElectronicsImperial College London, South Kensington CampusLondonUK
| | - Juan Manuel Moreno‐Naranjo
- Centre for Processable ElectronicsImperial College London, South Kensington CampusLondonUK
- Department of Chemistry and Molecular Sciences Research HubImperial College London, White City CampusLondonUK
| | - Seán Ryan
- Department of Chemistry and Molecular Sciences Research HubImperial College London, White City CampusLondonUK
| | - Giuliano Siligardi
- B23 Beamline, Diamond Light Source Ltd, Harwell Science and Innovation CampusDidcotUK
| | - Matthew J. Fuchter
- Centre for Processable ElectronicsImperial College London, South Kensington CampusLondonUK
- Department of Chemistry and Molecular Sciences Research HubImperial College London, White City CampusLondonUK
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5
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Liu W, Andrienko D. An ab initio method on large sized molecular aggregate system: Predicting absorption spectra of crystalline organic semiconducting films. J Chem Phys 2023; 158:094108. [PMID: 36889948 DOI: 10.1063/5.0138748] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Theoretical description of electronically excited states of molecular aggregates at an ab initio level is computationally demanding. To reduce the computational cost, we propose a model Hamiltonian approach that approximates the electronically excited state wavefunction of the molecular aggregate. We benchmark our approach on a thiophene hexamer, as well as calculate the absorption spectra of several crystalline non-fullerene acceptors, including Y6 and ITIC, which are known for their high power conversion efficiency in organic solar cells. The method qualitatively predicts the experimentally measured spectral shape, which can be further linked to the molecular arrangement in the unit cell.
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Affiliation(s)
- Wenlan Liu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Denis Andrienko
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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6
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Ghosh R, Paesani F. Connecting the dots for fundamental understanding of structure-photophysics-property relationships of COFs, MOFs, and perovskites using a Multiparticle Holstein Formalism. Chem Sci 2023; 14:1040-1064. [PMID: 36756323 PMCID: PMC9891456 DOI: 10.1039/d2sc03793a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 11/09/2022] [Indexed: 11/17/2022] Open
Abstract
Photoactive organic and hybrid organic-inorganic materials such as conjugated polymers, covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and layered perovskites, display intriguing photophysical signatures upon interaction with light. Elucidating structure-photophysics-property relationships across a broad range of functional materials is nontrivial and requires our fundamental understanding of the intricate interplay among excitons (electron-hole pair), polarons (charges), bipolarons, phonons (vibrations), inter-layer stacking interactions, and different forms of structural and conformational defects. In parallel with electronic structure modeling and data-driven science that are actively pursued to successfully accelerate materials discovery, an accurate, computationally inexpensive, and physically-motivated theoretical model, which consistently makes quantitative connections with conceptually complicated experimental observations, is equally important. Within this context, the first part of this perspective highlights a unified theoretical framework in which the electronic coupling as well as the local coupling between the electronic and nuclear degrees of freedom can be efficiently described for a broad range of quasiparticles with similarly structured Holstein-style vibronic Hamiltonians. The second part of this perspective discusses excitonic and polaronic photophysical signatures in polymers, COFs, MOFs, and perovskites, and attempts to bridge the gap between different research fields using a common theoretical construct - the Multiparticle Holstein Formalism. We envision that the synergistic integration of state-of-the-art computational approaches with the Multiparticle Holstein Formalism will help identify and establish new, transformative design strategies that will guide the synthesis and characterization of next-generation energy materials optimized for a broad range of optoelectronic, spintronic, and photonic applications.
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Affiliation(s)
- Raja Ghosh
- Department of Chemistry and Biochemistry, University of California La Jolla San Diego California 92093 USA
| | - Francesco Paesani
- Department of Chemistry and Biochemistry, University of California La Jolla San Diego California 92093 USA
- San Diego Supercomputer Center, University of California La Jolla San Diego California 92093 USA
- Materials Science and Engineering, University of California La Jolla San Diego California 92093 USA
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7
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Abstract
A comparison of four approaches to account the vibronic coupling in photoabsorption is performed. The methods considered are nuclear ensemble (NE), direct vibronic coupling (DVC), adiabatic Hessian (AH), and vertical gradient (VG). The case study is the symmetry-forbidden [Formula: see text] [Formula: see text]A[Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text]A[Formula: see text] (n [Formula: see text] [Formula: see text]) transition in formaldehyde. Being forbidden in the equilibrium geometry, this transition is entirely induced by vibronic coupling and constitutes an appropriate case to study the performance of different methods. From DVC, it is found that mode 1 (C=O out-of-plane bending) is the most inducing, followed by mode 6 (in-plane C-H asymmetric stretching) and finally by mode 2 (in-plane C-H asymmetric bending). We were able to correlate 17 out of 20 structures obtained from NE with these modes, showing that these two methods, although different in principle, give comparable results. The simulated spectra were obtained for all methods and compared, and each one has its own advantage. In what concerns the transition studied, NE gives the best description of the spectrum, DVC is the only one that easily gives an absolute value for OOS, and AH and VG are the computationally less expensive methods. From the latter two, VG is the less demanding on computational grounds, since it does not require the excited state Hessian.
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8
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Navamani K, Rajkumar K. Generalization on Entropy-Ruled Charge and Energy Transport for Organic Solids and Biomolecular Aggregates. ACS OMEGA 2022; 7:27102-27115. [PMID: 35967056 PMCID: PMC9366796 DOI: 10.1021/acsomega.2c01118] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 07/13/2022] [Indexed: 05/27/2023]
Abstract
Herein, a generalized version of the entropy-ruled charge and energy transport mechanism for organic solids and biomolecular aggregates is presented. The effects of thermal disorder and electric field on electronic transport in molecular solids have been quantified by entropy, which eventually varies with respect to the typical disorder (static or dynamic). Based on our previous differential entropy (h s )-driven charge transport method, we explore the nonsteady carrier energy flux principle for soft matter systems from small organic solids to macrobiomolecular aggregates. Through this principle, the synergic nature of charge and energy transport in different organic systems is addressed. In this work, entropy is the key parameter to classify whether the carrier dynamics is in a nonsteady or steady state. Besides that, we also propose the formulation for unifying the hopping and band transport, which provides the relaxation time-hopping rate relation and the relaxation time-effective mass ratio. The calculated disorder drift time (or entropy-weighted carrier drift time) for hole transport in an alkyl-substituted triphenylamine (TPA) molecular device is 9.3 × 10-7 s, which illustrates nuclear dynamics-coupled charge transfer kinetics. The existence of nonequilibrium transport is anticipated while the carrier dynamics is in the nonsteady state, which is further examined from the rate of traversing potential in octupolar molecules. Our entropy-ruled Einstein model connects the adiabatic band and nonadiabatic hopping transport mechanisms. The logarithmic current density at different electric field-assisted site energy differences provides information about the typical transport (whether trap-free diffusion or trap-assisted recombination) in molecular devices, which reflects in the Navamani-Shockley diode equation.
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Affiliation(s)
- Karuppuchamy Navamani
- Department
of Physics, Centre for Research and Development
(CFRD), KPR Institute of Engineering and Technology, Coimbatore 641407, India
| | - Kanakaraj Rajkumar
- Department
of Physics, Indian Institute of Technology
Madras, Chennai 600036, India
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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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Park KS, Xue Z, Patel BB, An H, Kwok JJ, Kafle P, Chen Q, Shukla D, Diao Y. Chiral emergence in multistep hierarchical assembly of achiral conjugated polymers. Nat Commun 2022; 13:2738. [PMID: 35585050 PMCID: PMC9117306 DOI: 10.1038/s41467-022-30420-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 04/27/2022] [Indexed: 11/09/2022] Open
Abstract
Intimately connected to the rule of life, chirality remains a long-time fascination in biology, chemistry, physics and materials science. Chiral structures, e.g., nucleic acid and cholesteric phase developed from chiral molecules are common in nature and synthetic soft materials. While it was recently discovered that achiral but bent-core mesogens can also form chiral helices, the assembly of chiral microstructures from achiral polymers has rarely been explored. Here, we reveal chiral emergence from achiral conjugated polymers, in which hierarchical helical structures are developed through a multistep assembly pathway. Upon increasing concentration beyond a threshold volume fraction, dispersed polymer nanofibers form lyotropic liquid crystalline (LC) mesophases with complex, chiral morphologies. Combining imaging, X-ray and spectroscopy techniques with molecular simulations, we demonstrate that this structural evolution arises from torsional polymer molecules which induce multiscale helical assembly, progressing from nano- to micron scale helical structures as the solution concentration increases. This study unveils a previously unknown complex state of matter for conjugated polymers that can pave way to a field of chiral (opto)electronics. We anticipate that hierarchical chiral helical structures can profoundly impact how conjugated polymers interact with light, transport charges, and transduce signals from biomolecular interactions and even give rise to properties unimagined before.
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Affiliation(s)
- Kyung Sun Park
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA
| | - Zhengyuan Xue
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA
| | - Bijal B Patel
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA
| | - Hyosung An
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA
| | - Justin J Kwok
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA
| | - Prapti Kafle
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA
| | - Qian Chen
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA
| | - Diwakar Shukla
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA
| | - Ying Diao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA.
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA.
- Beckman Institute, Molecular Science and Engineering, University of Illinois at Urbana-Champaign, 405 N. Mathews Ave., Urbana, IL, 61801, USA.
- Department of Chemistry, University of Illinois at Urbana-Champaign, 505 S. Mathews Ave., Urbana, IL, 61801, USA.
- Materials Research Laboratory, The Grainger College of Engineering, University of Illinois at Urbana-Champaign, 104 S. Goodwin Ave., Urbana, IL, 61801, USA.
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11
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Dimitriev OP. Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems. Chem Rev 2022; 122:8487-8593. [PMID: 35298145 DOI: 10.1021/acs.chemrev.1c00648] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The exciton, an excited electron-hole pair bound by Coulomb attraction, plays a key role in photophysics of organic molecules and drives practically important phenomena such as photoinduced mechanical motions of a molecule, photochemical conversions, energy transfer, generation of free charge carriers, etc. Its behavior in extended π-conjugated molecules and disordered organic films is very different and very rich compared with exciton behavior in inorganic semiconductor crystals. Due to the high degree of variability of organic systems themselves, the exciton not only exerts changes on molecules that carry it but undergoes its own changes during all phases of its lifetime, that is, birth, conversion and transport, and decay. The goal of this review is to give a systematic and comprehensive view on exciton behavior in π-conjugated molecules and molecular assemblies at all phases of exciton evolution with emphasis on rates typical for this dynamic picture and various consequences of the above dynamics. To uncover the rich variety of exciton behavior, details of exciton formation, exciton transport, exciton energy conversion, direct and reverse intersystem crossing, and radiative and nonradiative decay are considered in different systems, where these processes lead to or are influenced by static and dynamic disorder, charge distribution symmetry breaking, photoinduced reactions, electron and proton transfer, structural rearrangements, exciton coupling with vibrations and intermediate particles, and exciton dissociation and annihilation as well.
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Affiliation(s)
- Oleg P Dimitriev
- V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, pr. Nauki 41, Kyiv 03028, Ukraine
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12
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Paul S, Karunakaran V. Excimer Formation Inhibits the Intramolecular Singlet Fission Dynamics: Systematic Tilting of Pentacene Dimers by Linking Positions. J Phys Chem B 2022; 126:1054-1062. [PMID: 35107283 DOI: 10.1021/acs.jpcb.1c07951] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The role of excimer formation in inhibiting or enhancing the efficiency of the intramolecular singlet fission (iSF) process has been a subject of recent debate. Here, we investigated the effect of excimer formation on iSF dynamics by modifying its configuration by connecting pentacenes at various positions. Hence, pentacene dimers having slip-stacked (2,2' BP, J-type), oblique (2,6' BP), and facial (6,6' BP, H-type) configurations were synthesized by covalently linking pentacenes at positions 2,2', 2,6', and 6,6', respectively, with an ethynyl bridge, and their ultrafast excited-state relaxation dynamics were characterized. Femtosecond time-resolved transient absorption spectra revealed that the efficiency of iSF dynamics decreased from slip-stacked (182%) to oblique configuration (97%),whereas in the 6,6' BP with facial configuration, strong electronic coupling led to the formation of excimers that decayed nonradiatively without formation of correlated triplet pairs. These studies reveal the formation of excimers by strong intrapentacene electronic coupling upon ultrafast excitation, preventing the efficient iSF process.
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Affiliation(s)
- Sumitha Paul
- Photosciences and Photonics Section, Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, Kerala 695 019, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Venugopal Karunakaran
- Photosciences and Photonics Section, Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, Kerala 695 019, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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13
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Manousiouthakis E, Park J, Hardy JG, Lee JY, Schmidt CE. Towards the translation of electroconductive organic materials for regeneration of neural tissues. Acta Biomater 2022; 139:22-42. [PMID: 34339871 DOI: 10.1016/j.actbio.2021.07.065] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/23/2021] [Accepted: 07/27/2021] [Indexed: 12/13/2022]
Abstract
Carbon-based conductive and electroactive materials (e.g., derivatives of graphene, fullerenes, polypyrrole, polythiophene, polyaniline) have been studied since the 1970s for use in a broad range of applications. These materials have electrical properties comparable to those of commonly used metals, while providing other benefits such as flexibility in processing and modification with biologics (e.g., cells, biomolecules), to yield electroactive materials with biomimetic mechanical and chemical properties. In this review, we focus on the uses of these electroconductive materials in the context of the central and peripheral nervous system, specifically recent studies in the peripheral nerve, spinal cord, brain, eye, and ear. We also highlight in vivo studies and clinical trials, as well as a snapshot of emerging classes of electroconductive materials (e.g., biodegradable materials). We believe such specialized electrically conductive biomaterials will clinically impact the field of tissue regeneration in the foreseeable future. STATEMENT OF SIGNIFICANCE: This review addresses the use of conductive and electroactive materials for neural tissue regeneration, which is of significant interest to a broad readership, and of particular relevance to the growing community of scientists, engineers and clinicians in academia and industry who develop novel medical devices for tissue engineering and regenerative medicine. The review covers the materials that may be employed (primarily focusing on derivatives of fullerenes, graphene and conjugated polymers) and techniques used to analyze materials composed thereof, followed by sections on the application of these materials to nervous tissues (i.e., peripheral nerve, spinal cord, brain, optical, and auditory tissues) throughout the body.
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Affiliation(s)
- Eleana Manousiouthakis
- Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville 32611, FL, United States
| | - Junggeon Park
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - John G Hardy
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom; Materials Science Institute, Lancaster University, Lancaster LA1 4YB, United Kingdom.
| | - Jae Young Lee
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea.
| | - Christine E Schmidt
- Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville 32611, FL, United States.
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14
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Danielsen SPO, Bridges CR, Segalman RA. Chain Stiffness of Donor–Acceptor Conjugated Polymers in Solution. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Scott P. O. Danielsen
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Colin R. Bridges
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Mitsubishi Chemical Center for Advanced Materials, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Rachel A. Segalman
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Mitsubishi Chemical Center for Advanced Materials, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States
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15
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Bressan G, Jirasek M, Roy P, Anderson HL, Meech SR, Heisler IA. Population and Coherence Dynamics in Large Conjugated Porphyrin Nanorings. Chem Sci 2022; 13:9624-9636. [PMID: 36091893 PMCID: PMC9400675 DOI: 10.1039/d2sc01971j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 07/12/2022] [Indexed: 11/28/2022] Open
Abstract
In photosynthesis, nature exploits the distinctive electronic properties of chromophores arranged in supramolecular rings for efficient light harvesting. Among synthetic supramolecular cyclic structures, porphyrin nanorings have attracted considerable attention as they have a resemblance to naturally occurring light-harvesting structures but offer the ability to control ring size and the level of disorder. Here, broadband femtosecond transient absorption spectroscopy, with pump pulses in resonance with either the high or the low energy sides of the inhomogeneously broadened absorption spectrum, is used to study the population dynamics and ground and excited state vibrational coherence in large porphyrin nanorings. A series of fully conjugated, alkyne bridged, nanorings constituted of between ten and forty porphyrin units is studied. Pump-wavelength dependent fast spectral evolution is found. A fast rise or decay of the stimulated emission is found when large porphyrin nanorings are excited on, respectively, the high or low energy side of the absorption spectrum. Such dynamics are consistent with the hypothesis of a variation in transition dipole moment across the inhomogeneously broadened ground state ensemble. The observed dynamics indicate the interplay of nanoring conformation and oscillator strength. Oscillatory dynamics on the sub-ps time domain are observed in both pumping conditions. A combined analysis of the excitation wavelength-dependent transient spectra along with the amplitude and phase evolution of the oscillations allows assignment to vibrational wavepackets evolving on either ground or excited states electronic potential energy surfaces. Even though porphyrin nanorings support highly delocalized electronic wavefunctions, with coherence length spanning tens of chromophores, the measured vibrational coherences remain localised on the monomers. The main contributions to the beatings are assigned to two vibrational modes localised on the porphyrin cores: a Zn–N stretching mode and a skeletal methinic/pyrrolic C–C stretching and in-plane bending mode. Pump wavelength-dependent, ultrafast excited state dynamics arising from inhomogeneous broadening and ground and excited state nuclear wavepackets were observed for a series of Zn porphyrin nanorings made of 10 to 40 repeating units.![]()
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Affiliation(s)
- Giovanni Bressan
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Michael Jirasek
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory Oxford OX1 3TA UK
| | - Palas Roy
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Harry L Anderson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory Oxford OX1 3TA UK
| | - Stephen R Meech
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Ismael A Heisler
- Instituto de Física, Universidade Federal do Rio Grande do Sul Avenida Bento Gonçalves, 9500, CEP 91501-970 Porto Alegre Brazil
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16
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Laidlaw B, Eng J, Wade J, Shi X, Salerno F, Fuchter MJ, Penfold TJ. On the factors influencing the chiroptical response of conjugated polymer thin films. Chem Commun (Camb) 2021; 57:9914-9917. [PMID: 34498020 DOI: 10.1039/d1cc02918e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the influence of the physical and chemical structure on the chiroptical response of fluorene-based polymeric systems, namely poly(9,9-dioctylfluorene) (PFO) and the donor-acceptor type copolymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT). We reveal the significance of electric-magnetic coupling, at both short (molecular-level) and intermediate (delocalised over multiple polymer chains) length scales, on the magnitude of the dissymmetry. These findings provide a framework for the design of new materials with an enhanced chiroptical response.
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Affiliation(s)
- Beth Laidlaw
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Julien Eng
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Jessica Wade
- Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,Centre for Processable Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Xingyuan Shi
- Centre for Processable Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
| | - Francesco Salerno
- Centre for Processable Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
| | - Matthew J Fuchter
- Centre for Processable Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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17
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Turkin A, Malý P, Lambert C. Fluorescence band exchange narrowing in a series of squaraine oligomers: energetic vs. structural disorder. Phys Chem Chem Phys 2021; 23:18393-18403. [PMID: 34612380 DOI: 10.1039/d1cp02136b] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The influence of oligosquaraine chain length on the energies and shape of absorption and emission bands and the exciton coherence length is studied in CHCl3 where the oligomers adopt a random coil structure. From the observed fluorescence band narrowing an effective coherence length of Ncoh = 2.5 was estimated for the nonamer. Applying a theoretical Frenkel exciton model the absorption and emission spectra were simulated which confirmed the experimental results. From the relative amplitude of the 00 peak to the vibronic shoulder the coherence length was estimated which yields a somewhat higher saturation value of Ncoh≈ 3 for the nonamer, which is in very good agreement with the theoretical amplitude ratio. The coherence length is much smaller than the geometrical length because the electronic delocalisation is reduced by structural disorder. Taking into account the energetic (diagonal) and structural (off-diagonal) disorder we observed a different influence on the absorption and fluorescence spectra. For the emission spectra, exciton delocalisation leads to a narrowing of the band caused by averaging over energetic disorder, but for the absorption band the spectra are broadened by excitonic splitting and structural disorder.
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Affiliation(s)
- Arthur Turkin
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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18
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Javed N, O'Carroll DM. Long-term effects of impurities on the particle size and optical emission of carbon dots. NANOSCALE ADVANCES 2021; 3:182-189. [PMID: 36131876 PMCID: PMC9417521 DOI: 10.1039/d0na00479k] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/24/2020] [Indexed: 05/05/2023]
Abstract
Carbon dots (CDs) are fluorescent nanoparticles that exhibit strong photoluminescence (PL) emission throughout the visible range of the electromagnetic spectrum. Recent studies highlight the presence of fluorescent impurities in CD dispersions. Here, the long-term impact of these impurities on the stability of the physical and optical properties of CDs synthesized by the solvothermal method is studied. A significant increase in particle size is observed as a function of time after synthesis from transmission electron microscopy analysis of CDs. Furthermore, the quantum yield of blue PL emission, which is mostly caused by impurities that contain carboxyl groups, gradually decays from 30% to ∼3% over 13 weeks. The reduction in quantum yield is attributed to decomposition of impurities that, consequently, deposit on the particles and increase particle size. Finally, it is observed that the blue emission decreases considerably when CDs are properly purified and a solvent-dependent yellow emission arises. The yellow emission is almost negligible when CDs are dispersed in water; however, the intensity of yellow emission increases significantly when the concentration of ethanol is increased.
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Affiliation(s)
- Nasir Javed
- Department of Materials Science and Engineering, Rutgers, The State University of New Jersey 607 Taylor Road Piscataway NJ 08854 USA
| | - Deirdre M O'Carroll
- Department of Materials Science and Engineering, Rutgers, The State University of New Jersey 607 Taylor Road Piscataway NJ 08854 USA
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey 123 Bevier Road Piscataway NJ 08854 USA
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19
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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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20
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Abstract
ConspectusExcitons and polarons play a central role in the electronic and optical properties of organic semiconducting polymers and molecular aggregates and are of fundamental importance in understanding the operation of organic optoelectronic devices such as solar cells and light-emitting diodes. For many conjugated organic molecules and polymers, the creation of neutral electronic excitations or ionic radicals is associated with significant nuclear relaxation, the bulk of which occurs along the vinyl-stretching mode or the aromatic-quinoidal stretching mode when conjugated rings are present. Within a polymer chain or molecular aggregate, nuclear relaxation competes with energy- and charge-transfer, mediated by electronic interactions between the constituent units (repeat units for polymers and individual chromophores for a molecular aggregate); for neutral electronic excitations, such inter-unit interactions lead to extended excited states or excitons, while for positive (or negative) charges, interactions lead to delocalized hole (or electron) polarons. The electronic coupling as well as the local coupling between electronic and nuclear degrees of freedom in both excitons and polarons can be described with a Holstein Hamiltonian. However, although excitons and polarons derive from similarly structured Hamiltonians, their optical signatures are quite distinct, largely due to differing ground states and optical selection rules.In this Account, we explore the similarities and differences in the spectral response of excitons and polarons in organic polymers and molecular aggregates. We limit our analysis to the subspace of excitons and hole polarons containing at most one excitation; hence we omit the influence of bipolarons, biexcitons, and higher multiparticle excitations. Using a generic linear array of coupled units as a model host for both excitons and polarons, we compare and contrast the optical responses of both quasiparticles, with a particular emphasis on the spatial coherence length, the length over which an exciton or polaron possesses wave-like properties important for more efficient transport. For excitons, the UV-vis absorption spectrum is generally represented by a distorted vibronic progression with H-like or J-like signatures depending on the sign of the electronic coupling, Jex. The spectrum broadens with increasing site disorder, with the spectral area preserved due to an oscillator strength sum rule. For (hole) polarons, the generally stronger electronic coupling results in a mid-IR spectrum consisting of a narrow, low-energy peak (A) with energy near a vibrational quantum of the vinyl stretching mode, and a broader, higher-energy feature (B). In contrast to the UV-vis spectrum, the mid-IR spectrum is invariant to the sign of the electronic coupling, th, and completely resistant to long-range disorder, where it remains entirely homogeneously broadened. Even in the presence of short-range disorder, the width of peak A remains surprisingly narrow as long as |th| remains sufficiently large, a property that can be understood in terms of Herzberg-Teller coupling. Unlike for excitons, for polarons, the absorption spectral area decreases with increasing short-range disorder σ (i.e., there is no oscillator sum rule) reflective of a decreasing polaron coherence length. The intensity of the low-energy peak A in relation to B is an important signature of polaron coherence. By contrast, for excitons, the absorption spectrum contains no unambiguous signs of exciton coherence. One must instead resort to the shape of the steady-state photoluminescence spectrum. The Holstein-based model has been highly successful in accounting for the spectral properties of molecular aggregates as well as conjugated polymers like poly(3-hexylthiophene) (P3HT) in the mid-IR and UV-vis spectral regions.
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Affiliation(s)
- Raja Ghosh
- Department of Chemistry Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Frank C. Spano
- Department of Chemistry Temple University, Philadelphia, Pennsylvania 19122, United States
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21
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Liu Y, Liu J, Chen D, Wang X, Zhang Z, Yang Y, Jiang L, Qi W, Ye Z, He S, Liu Q, Xi L, Zou Y, Wu C. Fluorination Enhances NIR‐II Fluorescence of Polymer Dots for Quantitative Brain Tumor Imaging. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202007886] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Ye Liu
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center Central South University Changsha 410083 China
| | - Jinfeng Liu
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center Central South University Changsha 410083 China
| | - Dandan Chen
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Xiaosha Wang
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center Central South University Changsha 410083 China
| | - Zhe Zhang
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Yicheng Yang
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Lihui Jiang
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center Central South University Changsha 410083 China
| | - Weizhi Qi
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Ziyuan Ye
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Shuqing He
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Quanying Liu
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Lei Xi
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Yingping Zou
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center Central South University Changsha 410083 China
| | - Changfeng Wu
- Department of Biomedical Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China
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22
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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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23
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Liu Y, Liu J, Chen D, Wang X, Zhang Z, Yang Y, Jiang L, Qi W, Ye Z, He S, Liu Q, Xi L, Zou Y, Wu C. Fluorination Enhances NIR-II Fluorescence of Polymer Dots for Quantitative Brain Tumor Imaging. Angew Chem Int Ed Engl 2020; 59:21049-21057. [PMID: 32767727 DOI: 10.1002/anie.202007886] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/15/2020] [Indexed: 12/24/2022]
Abstract
Here, we describe a fluorination strategy for semiconducting polymers for the development of highly bright second near-infrared region (NIR-II) probes. Tetrafluorination yielded a fluorescence QY of 3.2 % for the polymer dots (Pdots), over a 3-fold enhancement compared to non-fluorinated counterparts. The fluorescence enhancement was attributable to a nanoscale fluorous effect in the Pdots that maintained the molecular planarity and minimized the structure distortion between the excited state and ground state, thus reducing the nonradiative relaxations. By performing through-skull and through-scalp imaging of the brain vasculature of live mice, we quantitatively analyzed the vascular morphology of transgenic brain tumors in terms of the vessel lengths, vessel branches, and vessel symmetry, which showed statistically significant differences from the wild type animals. The bright NIR-II Pdots obtained through fluorination chemistry provide insightful information for precise diagnosis of the malignancy of the brain tumor.
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Affiliation(s)
- Ye Liu
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center, Central South University, Changsha, 410083, China
| | - Jinfeng Liu
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center, Central South University, Changsha, 410083, China
| | - Dandan Chen
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Xiaosha Wang
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center, Central South University, Changsha, 410083, China
| | - Zhe Zhang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Yicheng Yang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Lihui Jiang
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center, Central South University, Changsha, 410083, China
| | - Weizhi Qi
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Ziyuan Ye
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Shuqing He
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Quanying Liu
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Lei Xi
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Yingping Zou
- College of Chemistry and Chemical Engineering, Molecular Imaging Research Center, Central South University, Changsha, 410083, China
| | - Changfeng Wu
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
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24
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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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25
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Binder R, Burghardt I. First-principles description of intra-chain exciton migration in an oligo(para-phenylene vinylene) chain. II. ML-MCTDH simulations of exciton dynamics at a torsional defect. J Chem Phys 2020; 152:204120. [DOI: 10.1063/5.0004511] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- 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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26
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Marcus M, Knee GC, Datta A. Towards a spectroscopic protocol for unambiguous detection of quantum coherence in excitonic energy transport. Faraday Discuss 2020; 221:110-132. [DOI: 10.1039/c9fd00068b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We propose a witness for quantum coherence in EET that can be extracted directly from two-pulse pump–probe spectroscopy experimental data.
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Affiliation(s)
- Max Marcus
- Department of Physics
- University of Warwick
- Coventry
- UK
| | | | - Animesh Datta
- Department of Physics
- University of Warwick
- Coventry
- UK
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27
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Binder R, Burghardt I. First-principles quantum simulations of exciton diffusion on a minimal oligothiophene chain at finite temperature. Faraday Discuss 2020; 221:406-427. [PMID: 31596291 DOI: 10.1039/c9fd00066f] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
High-dimensional multiconfigurational quantum dynamics simulations are carried out at finite temperature to simulate exciton diffusion on an oligothiophene chain, representative of a segment of the poly(3-hexylthiophene) (P3HT) polymer. The ab initio parametrized site-based Hamiltonian of Binder et al. [Phys. Rev. Lett., 2018, 120, 227401] is employed to model a 20-site system, including intra-ring and inter-ring high-frequency modes as well as torsional modes which undergo thermal fluctuations induced by an explicit harmonic oscillator bath. The system-bath dynamics is treated within the setting of a stochastic mean-field Schrödinger equation. For the 20-site excitonic system, a total of 20 Frenkel states and 248 modes are propagated using the multi-layer multi-configuration time-dependent Hartree (ML-MCTDH) method. The resulting dynamics can be interpreted in terms of the coherent motion of an exciton-polaron quasi-particle stochastically driven by torsional fluctuations. This dynamics yields a near-linear mean squared displacement (MSD) as a function of time, from which a diffusion coefficient can be deduced which increases with temperature, up to 5.7 × 10-3 cm2 s-1 at T = 300 K.
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Affiliation(s)
- Robert Binder
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany.
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28
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Jackson NE, Bowen AS, de Pablo JJ. Efficient Multiscale Optoelectronic Prediction for Conjugated Polymers. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b02020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Nicholas E. Jackson
- Center for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Alec S. Bowen
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Juan J. de Pablo
- Center for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
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29
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Barford W, Gardner JLA, Mannouch JR. Using spectroscopy to probe relaxation, decoherence, and localization of photoexcited states in π-conjugated polymers. Faraday Discuss 2019; 221:281-298. [PMID: 31539013 DOI: 10.1039/c9fd00054b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We use the coarse-grained Frenkel-Holstein model to simulate the relaxation, decoherence, and localization of photoexcited states in conformationally disordered π-conjugated polymers. The dynamics are computed via wave-packet propagation using matrix product states and the time evolution block decimation method. The ultrafast (i.e., t < 10 fs) coupling of an exciton to C-C bond vibrations creates an exciton-polaron. The relatively short (ca. 10 monomers) exciton-phonon correlation length causes ultrafast exciton-site decoherence, which is observable on conformationally disordered chains as fluorescence depolarization. Dissipative coupling to the environment (modelled via quantum jumps) causes the localization of quasi-extended exciton states (QEESs) onto local exciton ground states (LEGSs, i.e., chromophores). This is observable as lifetime broadening of the 0-0 transition (and vibronic satellites) of the QEES in two-dimensional electronic coherence spectroscopy. However, as this process is incoherent, neither population increases of the LEGSs nor coherences with LEGSs are observable.
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Affiliation(s)
- William Barford
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.
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30
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Royakkers J, Minotto A, Congrave DG, Zeng W, Patel A, Bond AD, Bučar DK, Cacialli F, Bronstein H. Doubly Encapsulated Perylene Diimides: Effect of Molecular Encapsulation on Photophysical Properties. J Org Chem 2019; 85:207-214. [PMID: 31682123 DOI: 10.1021/acs.joc.9b02597] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intermolecular interactions play a fundamental role on the performance of conjugated materials in organic electronic devices, as they heavily influence their optoelectronic properties. Synthetic control over the solid state properties of organic optoelectronic materials is crucial to access real life applications. Perylene diimides (PDIs) are one of the most highly studied classes of organic fluorescent dyes. In the solid state, π-π stacking suppresses their emission, limiting their use in a variety of applications. Here, we report the synthesis of a novel PDI dye that is encapsulated by four alkylene straps. X-ray crystallography indicates that intermolecular π-π stacking is completely suppressed in the crystalline state. This is further validated by the photophysical properties of the dye in both solution and solid state and supported by theoretical calculations. However, we find that the introduction of the encapsulating "arms" results in the creation of charge-transfer states which modify the excited state properties. This article demonstrates that molecular encapsulation can be used as a powerful tool to tune intermolecular interactions and thereby gain an extra level of control over the solid state properties of organic optoelectronic materials.
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Affiliation(s)
- Jeroen Royakkers
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom
| | - Alessandro Minotto
- Department of Physics and Astronomy and LCN , University College London , Gower Street , London WC1E 6BT , United Kingdom
| | - Daniel G Congrave
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom
| | - Weixuan Zeng
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom
| | - Adil Patel
- Department of Physics and Astronomy and LCN , University College London , Gower Street , London WC1E 6BT , United Kingdom
| | - Andrew D Bond
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom
| | - Dejan-Krešimir Bučar
- Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Franco Cacialli
- Department of Physics and Astronomy and LCN , University College London , Gower Street , London WC1E 6BT , United Kingdom
| | - Hugo Bronstein
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom.,Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , United Kingdom
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31
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Buchhorn M, Wedler S, Panzer F. Setup to Study the in Situ Evolution of Both Photoluminescence and Absorption during the Processing of Organic or Hybrid Semiconductors. J Phys Chem A 2018; 122:9115-9122. [PMID: 30358396 DOI: 10.1021/acs.jpca.8b07495] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In situ measurement techniques, applied during the solution processing of novel semiconductors such as organic semiconductors or hybrid perovskites, have become more and more important to understand their film formation. In that context, it is crucial to determine how the optical properties, namely photoluminescence (PL) and absorption, evolve during processing. However, until now PL and absorption have mostly been investigated independently, significantly reducing the potential insights into film formation dynamics. To tackle this issue we present the development of a detection system that allows simultaneous measurement of full absorption and PL spectra during solution processing of the investigated film. We also present a spin-coater system attachable to the detection system, where the temperature of the substrate on which the film is processed can be changed. We performed test measurements by spin coating the well-known conjugated polymer P3HT demonstrating the potential of this technique. By considering absorption and corresponding PL, we extract the PL quantum yield (PLQY) during processing, which decreases with substrate temperature. Furthermore, we identify a significant red shift of the PL just prior to the onset of the aggregation process, indicating the importance of chain planarization prior to solid film formation.
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Affiliation(s)
- Michael Buchhorn
- Soft Matter Optoelectronics , University of Bayreuth , Bayreuth 95440 , Germany
| | - Stefan Wedler
- Soft Matter Optoelectronics , University of Bayreuth , Bayreuth 95440 , Germany
| | - Fabian Panzer
- Soft Matter Optoelectronics , University of Bayreuth , Bayreuth 95440 , Germany
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32
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Yuan Z, Buckley C, Thomas S, Zhang G, Bargigia I, Wang G, Fu B, Silva C, Brédas JL, Reichmanis E. A Thiazole–Naphthalene Diimide Based n-Channel Donor–Acceptor Conjugated Polymer. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01829] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
| | | | | | | | | | - Gang Wang
- The Materials Research Center, Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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33
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Milward JD, Marcus M, Köhler A, Barford W. Extracting structural information from MEH-PPV optical spectra. J Chem Phys 2018; 149:044903. [PMID: 30068188 DOI: 10.1063/1.5041938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Frenkel-Holstein model in the Born-Oppenheimer regime is used to interpret temperature-dependent photoluminescence spectra of solutions made with the poly(p-phenylene vinylene) derivative MEH-PPV. Using our recently developed structural optimization method and assuming only intrachain electronic coupling, we predict the structure of emissive MEH-PPV chromophores in terms of a mean torsional angle ϕ0 and its static fluctuations σϕ, assuming no cis-trans defects. This allows us to fully account for the observed changes in spectra, and the chromophore structures obtained are consistent with the known phase transition at 180 K between a "red" and "blue" phase.
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Affiliation(s)
- Jonathan D Milward
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, United Kingdom
| | - Max Marcus
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, United Kingdom
| | - Anna Köhler
- Experimental Physics II, University of Bayreuth, 95447 Bayreuth, Germany and Bayreuth Institute of Macromolecular Research (BIMF), University of Bayreuth, 95447 Bayreuth, Germany
| | - William Barford
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, United Kingdom
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34
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Binder R, Lauvergnat D, Burghardt I. Conformational Dynamics Guides Coherent Exciton Migration in Conjugated Polymer Materials: First-Principles Quantum Dynamical Study. PHYSICAL REVIEW LETTERS 2018; 120:227401. [PMID: 29906150 DOI: 10.1103/physrevlett.120.227401] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Indexed: 06/08/2023]
Abstract
We report on high-dimensional quantum dynamical simulations of photoinduced exciton migration in a single-chain oligothiophene segment, in view of elucidating the controversial nature of the elementary exciton transport steps in semiconducting polymers. A novel first-principles parametrized Frenkel J aggregate Hamiltonian is employed that goes significantly beyond the standard Frenkel-Holstein Hamiltonian. Departing from a nonequilibrium state created by photoexcitation, these simulations provide evidence of an ultrafast two-timescale process at low temperatures, involving exciton-polaron formation within tens of femtoseconds (fs), followed by torsional relaxation on an ∼400 fs timescale. The second step is the driving force for exciton migration, as initial conjugation breaks are removed by dynamical planarization. The quantum coherent nature of the elementary exciton migration step is consistent with experimental observations highlighting the correlated and vibrationally coherent nature of the dynamics on ultrafast timescales.
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Affiliation(s)
- Robert Binder
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany
| | - David Lauvergnat
- Laboratoire de Chimie Physique, Université Paris-Sud, UMR 8000, 91405 Orsay, France
| | - Irene Burghardt
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany
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35
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Savikhin V, Jagadamma LK, Purvis LJ, Robertson I, Oosterhout SD, Douglas CJ, Samuel IDW, Toney MF. Morphological, Chemical, and Electronic Changes of the Conjugated Polymer PTB7 with Thermal Annealing. iScience 2018; 2:182-192. [PMID: 30428374 PMCID: PMC6135925 DOI: 10.1016/j.isci.2018.03.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 02/05/2018] [Accepted: 02/16/2018] [Indexed: 11/30/2022] Open
Abstract
There is considerable interest in improving the performance of organic optoelectronic devices through processing techniques. Here, we study the effect of high-temperature annealing on the properties of the semiconducting polymer PTB7 and PTB7:fullerene blends, of interest as efficient organic photovoltaic (OPV) devices. Annealing to moderate temperature improves the PTB7 morphology and optoelectronic properties. High-temperature annealing also improves morphology but results in poorer optoelectronic properties. This is a result of side chain cleavage that creates by-products that act as trap states, increasing electronic disorder and decreasing mobility. We further observe changes to the PTB7 chemical structure after thermal cleavage that are similar to those following solar irradiation. This implies that side chain cleavage is an important mechanism in device photodegradation, which is a major “burn-in” loss mechanism in OPV. These results lend insight into side chain cleavage as a method of improving optoelectronic properties and suggest strategies for improvement in device photostability. Annealing to 260°C improves morphology and hole mobility in PTB7-based thin films Annealing to 290°C induces side-chain cleavage and closer packing of PTB7 Thermally cleaved PTB7 films resemble irradiated films, suggesting a burn-in mechanism Release of trapped reaction by-products could result in improved device performance
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Affiliation(s)
- Victoria Savikhin
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA; Electrical Engineering Department, Stanford University, 350 Serra Mall, Stanford, CA 94305, USA
| | - Lethy K Jagadamma
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
| | - Lafe J Purvis
- Department of Chemistry, University of Minnesota - Twin Cities, 207 Pleasant St SE, Minneapolis, MN 55455, USA
| | - Iain Robertson
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
| | - Stefan D Oosterhout
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Christopher J Douglas
- Department of Chemistry, University of Minnesota - Twin Cities, 207 Pleasant St SE, Minneapolis, MN 55455, USA
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
| | - Michael F Toney
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
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36
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Hestand NJ, Spano FC. Expanded Theory of H- and J-Molecular Aggregates: The Effects of Vibronic Coupling and Intermolecular Charge Transfer. Chem Rev 2018; 118:7069-7163. [PMID: 29664617 DOI: 10.1021/acs.chemrev.7b00581] [Citation(s) in RCA: 742] [Impact Index Per Article: 123.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The electronic excited states of molecular aggregates and their photophysical signatures have long fascinated spectroscopists and theoreticians alike since the advent of Frenkel exciton theory almost 90 years ago. The influence of molecular packing on basic optical probes like absorption and photoluminescence was originally worked out by Kasha for aggregates dominated by Coulombic intermolecular interactions, eventually leading to the classification of J- and H-aggregates. This review outlines advances made in understanding the relationship between aggregate structure and photophysics when vibronic coupling and intermolecular charge transfer are incorporated. An assortment of packing geometries is considered from the humble molecular dimer to more exotic structures including linear and bent aggregates, two-dimensional herringbone and "HJ" aggregates, and chiral aggregates. The interplay between long-range Coulomb coupling and short-range charge-transfer-mediated coupling strongly depends on the aggregate architecture leading to a wide array of photophysical behaviors.
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Affiliation(s)
- Nicholas J Hestand
- Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Frank C Spano
- Department of Chemistry , Temple University , Philadelphia , Pennsylvania 19122 , United States
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37
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Marcus M, Milward JD, Köhler A, Barford W. Structural Information for Conjugated Polymers from Optical Modeling. J Phys Chem A 2018; 122:3621-3625. [PMID: 29565593 DOI: 10.1021/acs.jpca.8b01585] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We use a Frenkel-Holstein model of uncoupled chains in the adiabatic limit to simulate the optical spectra of the conjugated polymer ladder-type poly( p-phenylene) derivative (MeLPPP), which is a planar conjugated polymer with especially low interchain interactions. The theoretical calculations correctly reproduce the vibronic spectra and yield reasonable torsion angles between adjacent phenyl rings. The success of this approach indicates that, in contrast to interchain coupling, the strong electronic coupling along a polymer chain is more appropriately described in the adiabatic limit.
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Affiliation(s)
- Max Marcus
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory , University of Oxford , Oxford , OX1 3QZ , U.K.,Magdalen College , University of Oxford , Oxford , OX1 4AU , U.K
| | - Jonathan D Milward
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory , University of Oxford , Oxford , OX1 3QZ , U.K.,University College , University of Oxford , Oxford , OX1 4BH , U.K
| | - Anna Köhler
- Experimental Physics II , University of Bayreuth , 95447 Bayreuth , Germany.,Bayreuth Institut of Macromulecular Research (BIMF) , University of Bayreuth , 95447 Bayreuth , Germany
| | - William Barford
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory , University of Oxford , Oxford , OX1 3QZ , U.K
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38
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Raithel D, Simine L, Pickel S, Schötz K, Panzer F, Baderschneider S, Schiefer D, Lohwasser R, Köhler J, Thelakkat M, Sommer M, Köhler A, Rossky PJ, Hildner R. Direct observation of backbone planarization via side-chain alignment in single bulky-substituted polythiophenes. Proc Natl Acad Sci U S A 2018; 115:2699-2704. [PMID: 29483262 PMCID: PMC5856543 DOI: 10.1073/pnas.1719303115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The backbone conformation of conjugated polymers affects, to a large extent, their optical and electronic properties. The usually flexible substituents provide solubility and influence the packing behavior of conjugated polymers in films or in bad solvents. However, the role of the side chains in determining and potentially controlling the backbone conformation, and thus the optical and electronic properties on the single polymer level, is currently under debate. Here, we investigate directly the impact of the side chains by studying the bulky-substituted poly(3-(2,5-dioctylphenyl)thiophene) (PDOPT) and the common poly(3-hexylthiophene) (P3HT), both with a defined molecular weight and high regioregularity, using low-temperature single-chain photoluminescence (PL) spectroscopy and quantum-classical simulations. Surprisingly, the optical transition energy of PDOPT is significantly (∼2,000 cm-1 or 0.25 eV) red-shifted relative to P3HT despite a higher static and dynamic disorder in the former. We ascribe this red shift to a side-chain induced backbone planarization in PDOPT, supported by temperature-dependent ensemble PL spectroscopy. Our atomistic simulations reveal that the bulkier 2,5-dioctylphenyl side chains of PDOPT adopt a clear secondary helical structural motif and thus protect conjugation, i.e., enforce backbone planarity, whereas, for P3HT, this is not the case. These different degrees of planarity in both thiophenes do not result in different conjugation lengths, which we found to be similar. It is rather the stronger electronic coupling between the repeating units in the more planar PDOPT which gives rise to the observed spectral red shift as well as to a reduced calculated electron-hole polarization.
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Affiliation(s)
- Dominic Raithel
- Experimental Physics IV, University of Bayreuth, 95440 Bayreuth, Germany
| | - Lena Simine
- Department of Chemistry, Rice University, Houston, TX 77005
| | - Sebastian Pickel
- Experimental Physics IV, University of Bayreuth, 95440 Bayreuth, Germany
| | - Konstantin Schötz
- Experimental Physics II, University of Bayreuth, 95440 Bayreuth, Germany
| | - Fabian Panzer
- Experimental Physics II, University of Bayreuth, 95440 Bayreuth, Germany
| | | | - Daniel Schiefer
- Institute of Macromolecular Chemistry, University of Freiburg, 79104 Freiburg, Germany
| | - Ruth Lohwasser
- Applied Functional Polymers, University of Bayreuth, 95440 Bayreuth, Germany
| | - Jürgen Köhler
- Experimental Physics IV, University of Bayreuth, 95440 Bayreuth, Germany
- Bayreuth Institute of Macromolecular Research, University of Bayreuth, 95440 Bayreuth, Germany
| | - Mukundan Thelakkat
- Applied Functional Polymers, University of Bayreuth, 95440 Bayreuth, Germany
| | - Michael Sommer
- Institute of Macromolecular Chemistry, University of Freiburg, 79104 Freiburg, Germany
| | - Anna Köhler
- Experimental Physics II, University of Bayreuth, 95440 Bayreuth, Germany
- Bayreuth Institute of Macromolecular Research, University of Bayreuth, 95440 Bayreuth, Germany
| | - Peter J Rossky
- Department of Chemistry, Rice University, Houston, TX 77005
| | - Richard Hildner
- Experimental Physics IV, University of Bayreuth, 95440 Bayreuth, Germany;
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39
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Leventis A, Royakkers J, Rapidis AG, Goodeal N, Corpinot MK, Frost JM, Bučar DK, Blunt MO, Cacialli F, Bronstein H. Highly Luminescent Encapsulated Narrow Bandgap Polymers Based on Diketopyrrolopyrrole. J Am Chem Soc 2018; 140:1622-1626. [DOI: 10.1021/jacs.7b13447] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Anastasia Leventis
- Department of Chemistry & Physics, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Jeroen Royakkers
- Department of Chemistry & Physics, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Alexandros G. Rapidis
- Department
of Physics and Astronomy and LCN, University College London, Gower
Street, London WC1E 6BT, United Kingdom
| | - Niall Goodeal
- Department of Chemistry & Physics, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Merina K. Corpinot
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Jarvist M. Frost
- Department
of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Dejan-Krešimir Bučar
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Matthew Oliver Blunt
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Franco Cacialli
- Department
of Physics and Astronomy and LCN, University College London, Gower
Street, London WC1E 6BT, United Kingdom
| | - Hugo Bronstein
- Department of Chemistry & Physics, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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40
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Mannouch JR, Barford W, Al-Assam S. Ultra-fast relaxation, decoherence, and localization of photoexcited states in π-conjugated polymers. J Chem Phys 2018; 148:034901. [DOI: 10.1063/1.5009393] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jonathan R. Mannouch
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, United Kingdom
- University College, University of Oxford, Oxford OX1 4BH, United Kingdom
| | - William Barford
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, United Kingdom
| | - Sarah Al-Assam
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
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