1
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Adhikari S, Orrit M. Progress and perspectives in single-molecule optical spectroscopy. J Chem Phys 2022; 156:160903. [PMID: 35489995 DOI: 10.1063/5.0087003] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We review some of the progress of single-molecule optical experiments in the past 20 years and propose some perspectives for the coming years. We particularly focus on methodological advances in fluorescence, super-resolution, photothermal contrast, and interferometric scattering and briefly discuss a few of the applications. These advances have enabled the exploration of new emitters and quantum optics; the chemistry and biology of complex heterogeneous systems, nanoparticles, and plasmonics; and the detection and study of non-fluorescing and non-absorbing nano-objects. We conclude by proposing some ideas for future experiments. The field will move toward more and better signals of a broader variety of objects and toward a sharper view of the surprising complexity of the nanoscale world of single (bio-)molecules, nanoparticles, and their nano-environments.
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Affiliation(s)
- Subhasis Adhikari
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2333 CA Leiden, The Netherlands
| | - Michel Orrit
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2333 CA Leiden, The Netherlands
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2
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Eder T, Kraus D, Höger S, Vogelsang J, Lupton JM. Vibrations Responsible for Luminescence from HJ-Aggregates of Conjugated Polymers Identified by Cryogenic Spectroscopy of Single Nanoparticles. ACS NANO 2022; 16:6382-6393. [PMID: 35394735 DOI: 10.1021/acsnano.2c00472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A single polymer chain can be thought of as a covalently bound J-aggregate, where the microscopic transition-dipole moments line up to emit in phase. Packing polymer chains into a bulk film can result in the opposite effect, inducing H-type coupling between chains. Cofacial transition-dipole moments oscillate out of phase, canceling each other out, so that the lowest-energy excited state turns dark. H-aggregates of conjugated polymers can, in principle, be coaxed into emitting light by mixing purely electronic and vibronic transitions. However, it is challenging to characterize this electron-phonon coupling experimentally. In a bulk film, many different conformations exist with varying degrees of intrachain J-type and interchain H-type coupling strengths, giving rise to broad and featureless aggregate absorption and emission spectra. Even if single nanoparticles consisting of only a few single chains are grown in a controlled fashion, the luminescence spectra remain broad, owing to the underlying molecular dynamics and structural heterogeneity at room temperature. At cryogenic temperatures, emission from H-type aggregates should be suppressed because, in the absence of thermal energy, internal conversion drives the aggregate to the lowest-energy dark state. At the same time, electronic and vibronic transitions narrow substantially, facilitating the attribution of spectral signatures to distinct vibrational modes. We demonstrate how to distinguish signatures of interchain H-type aggregate species from those of intramolecular J-type coupling. Whereas all dominant vibronic modes revealed in the photoluminescence (PL) and surface-enhanced resonance Raman scattering spectra of a single chromophore within a single polymer chain are identified in the J-type aggregate luminescence spectra, they are not all present at once in the H-type spectra. Universal spectral features are found for the luminescence from strongly HJ-coupled chains, clearly resolving the vibrations responsible for the nonadiabatic excited-state molecular dynamics that enable light emission. We discuss the possible combinations of vibrational modes responsible for H-type aggregate PL and demonstrate that only one, mainly the lowest energy one, of the three dominant vibrational modes contributes to the 0-1 transition, whereas combinations of all three are found in the 0-2 transition. From this analysis, we can distinguish between energy shifts due to either J-type intrachain coupling or H-type interchain interactions, offering a means to directly discriminate between structural and energetic disorder.
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Affiliation(s)
- Theresa Eder
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - Daniel Kraus
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - Sigurd Höger
- Kekulé-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
| | - Jan Vogelsang
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - John M Lupton
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
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3
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van de Laar T, Hooiveld E, Higler R, van der Scheer P, Sprakel J. Gel Trapping Enables Optical Spectroscopy of Single Solvated Conjugated Polymers in Equilibrium. ACS NANO 2019; 13:13185-13195. [PMID: 31647632 PMCID: PMC6887849 DOI: 10.1021/acsnano.9b06164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 10/24/2019] [Indexed: 06/10/2023]
Abstract
Single-molecule studies have provided a wealth of insight into the photophysics of conjugated polymers in the solid and desolvated state. Desolvating conjugated chains, e.g., by their embedding in inert solid matrices, invariably leads to chain collapse and the formation of intermolecular aggregates, which have a pronounced effect on their properties. By contrast, the luminescent properties of individual semiconducting polymers in their solvated and thermodynamic state remain largely unexplored. In this paper, we demonstrate a versatile gel trapping technique that enables the chemistry-free immobilization and interrogation of individual conjugated macromolecules, which retain a fully equilibrated conformation by contrast to conventional solid-state immobilization methods. We show how the technique can be used to record full luminescence spectra of single chains, to evaluate their time-resolved fluorescence, and to probe their photodynamics. Finally, we explore how the photophysics of different conjugated polymers is strongly affected by desolvation and chain collapse.
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4
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Camacho R, Täuber D, Scheblykin IG. Fluorescence Anisotropy Reloaded-Emerging Polarization Microscopy Methods for Assessing Chromophores' Organization and Excitation Energy Transfer in Single Molecules, Particles, Films, and Beyond. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805671. [PMID: 30721532 DOI: 10.1002/adma.201805671] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/12/2018] [Indexed: 06/09/2023]
Abstract
Fluorescence polarization is widely used to assess the orientation/rotation of molecules, and the excitation energy transfer between closely located chromophores. Emerging since the 1990s, single molecule fluorescence spectroscopy and imaging stimulate the application of light polarization for studying molecular organization and energy transfer beyond ensemble averaging. Here, traditional fluorescence polarization and linear dichroism methods used for bulk samples are compared with techniques specially developed for, or inspired by, single molecule fluorescence spectroscopy. Techniques for assessing energy transfer in anisotropic samples, where the traditional fluorescence anisotropy framework is not readily applicable, are discussed in depth. It is shown that the concept of a polarization portrait and the single funnel approximation can lay the foundation for alternative energy transfer metrics. Examples ranging from fundamental studies of photoactive materials (conjugated polymers, light-harvesting aggregates, and perovskite semiconductors) to Förster resonant energy transfer (FRET)-based biomedical imaging are presented. Furthermore, novel uses of light polarization for super-resolution optical imaging are mentioned as well as strategies for avoiding artifacts in polarization microscopy.
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Affiliation(s)
- Rafael Camacho
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001, Leuven, Belgium
| | - Daniela Täuber
- Chemical Physics and NanoLund, Lund University, P.O. Box 124, SE-22100, Lund, Sweden
- Biopolarisation, Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745, Jena, Germany
- Institute of Solid State Physics, FSU Jena, Helmholtzweg 3, D-07743, Jena, Germany
| | - Ivan G Scheblykin
- Chemical Physics and NanoLund, Lund University, P.O. Box 124, SE-22100, Lund, Sweden
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5
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Lidster BJ, Hirata S, Matsuda S, Yamamoto T, Komanduri V, Kumar DR, Tezuka Y, Vacha M, Turner ML. Macrocyclic poly( p-phenylenevinylene)s by ring expansion metathesis polymerisation and their characterisation by single-molecule spectroscopy. Chem Sci 2018; 9:2934-2941. [PMID: 29732077 PMCID: PMC5915795 DOI: 10.1039/c7sc03945j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 02/12/2018] [Indexed: 12/04/2022] Open
Abstract
Ring expansion metathesis polymerisation (REMP) has proven to be a viable approach to prepare high purity macrocyclic phenylenevinylene polymers.
Ring expansion metathesis polymerisation (REMP) has proven to be a viable approach to prepare high purity cyclic polymers. Macrocyclic polymers with a fully conjugated defect free backbone are of particular interest as these polymers have no end groups that can act as charge traps. In this work soluble macrocyclic poly(p-phenylenevinylene)s (cPPVs) have been prepared directly via the REMP of substituted paracyclophanedienes. Single-molecule spectroscopy of the two topological forms of PPV i.e., linear (lPPV) and cyclic (cPPV) revealed that lPPV exists in an extended conformation whereas the cPPV adopts a restricted ring-like conformation. Despite such large differences in the chain conformation, the spectral properties of the two compounds are unexpectedly very similar, and are dominated by torsional deformations in relatively short conjugated segments.
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Affiliation(s)
- Benjamin John Lidster
- The School of Chemistry , The University of Manchester , Oxford Road , Manchester , M13 9PL , UK .
| | - Shuzo Hirata
- Department of Materials Science and Engineering , Tokyo Institute of Technology , Ookayama 2-12-1, Meguro-ku , Tokyo 152-8552 , Japan .
| | - Shoki Matsuda
- Department of Materials Science and Engineering , Tokyo Institute of Technology , Ookayama 2-12-1, Meguro-ku , Tokyo 152-8552 , Japan .
| | - Takuya Yamamoto
- Division of Applied Chemistry , Faculty of Engineering , Hokkaido University , Sapporo , Hokkaido 060-8628 , Japan
| | - Venukrishnan Komanduri
- The School of Chemistry , The University of Manchester , Oxford Road , Manchester , M13 9PL , UK .
| | - Dharam Raj Kumar
- The School of Chemistry , The University of Manchester , Oxford Road , Manchester , M13 9PL , UK .
| | - Yasuyuki Tezuka
- Department of Materials Science and Engineering , Tokyo Institute of Technology , Ookayama 2-12-1, Meguro-ku , Tokyo 152-8552 , Japan .
| | - Martin Vacha
- Department of Materials Science and Engineering , Tokyo Institute of Technology , Ookayama 2-12-1, Meguro-ku , Tokyo 152-8552 , Japan .
| | - Michael L Turner
- The School of Chemistry , The University of Manchester , Oxford Road , Manchester , M13 9PL , UK .
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6
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Hu Z, Shao B, Geberth GT, Vanden Bout DA. Effects of molecular architecture on morphology and photophysics in conjugated polymers: from single molecules to bulk. Chem Sci 2018; 9:1101-1111. [PMID: 29675155 PMCID: PMC5887865 DOI: 10.1039/c7sc03465b] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 12/30/2017] [Indexed: 01/16/2023] Open
Abstract
A definitive comprehension of morphology and photophysics in conjugated polymers at multiple length scales demands both single molecule spectroscopy and well-controlled molecular architectures.
Conjugated polymers (CPs) possess a wide range of desirable properties, including accessible energetic bandgaps, synthetic versatility, and mechanical flexibility, which make them attractive for flexible and wearable optoelectronic devices. An accurate and comprehensive understanding about the morphology–photophysics relations in CPs lays the groundwork for their development in these applications. However, due to the complex roles of chemical structure, side-chains, backbone, and intramolecular interactions, CPs can exhibit heterogeneity in both their morphology and optoelectronic properties even at the single chain level. This molecular level heterogeneity together with complicated intermolecular interactions found in bulk CP materials severely obscures the deterministic information about the morphology and photophysics at different hierarchy levels. To counter this complexity and offer a clearer picture for the properties of CP materials, we highlight the approach of probing material systems with specific structural features via single molecule/aggregate spectroscopy (SMS). This review article covers recent advances achieved through such an approach regarding the important morphological and photophysical properties of CPs. After a brief review of the typical characteristics of CPs, we present detailed discussions of structurally well-defined model systems of CPs, from manipulated backbones and side-chains, up to nano-aggregates, studied with SMS to offer deterministic relations between morphology and photophysics from single chains building up to bulk states.
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Affiliation(s)
- Zhongjian Hu
- Department of Chemistry , University of Texas at Austin , USA .
| | - Beiyue Shao
- Department of Chemistry , University of Texas at Austin , USA .
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7
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Hou L, Adhikari S, Tian Y, Scheblykin IG, Orrit M. Absorption and Quantum Yield of Single Conjugated Polymer Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) Molecules. NANO LETTERS 2017; 17:1575-1581. [PMID: 28221806 PMCID: PMC5345118 DOI: 10.1021/acs.nanolett.6b04726] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/14/2017] [Indexed: 05/28/2023]
Abstract
We simultaneously measured the absorption and emission of single conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) molecules in a poly(methyl methacrylate) (PMMA) matrix using near-critical xenon to enhance the photothermal contrast for direct absorption measurements. We directly measured the number of monomers and the quantum yield of single conjugated polymer molecules. Simultaneous absorption and emission measurements provided new insight into the photophysics of single conjugated polymers under optical excitation: quenching in larger molecules is more efficient than in smaller ones. Photoinduced traps and defects formed under prolonged illumination lead to decrease of both polymer fluorescence and absorption signals with the latter declining slower.
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Affiliation(s)
- Lei Hou
- LION, Huygens-Kamerlingh
Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2300RA Leiden, The Netherlands
| | - Subhasis Adhikari
- LION, Huygens-Kamerlingh
Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2300RA Leiden, The Netherlands
| | - Yuxi Tian
- Chemical Physics and Nano Lund, Lund University, P.O. Box 124, 22100 Lund, Sweden
- Key Laboratory of Mesoscopic
Chemistry of MOE and School of Chemistry and Chemical Engineering, Nanjing University, 210023 Nanjing, China
| | - Ivan G. Scheblykin
- Chemical Physics and Nano Lund, Lund University, P.O. Box 124, 22100 Lund, Sweden
| | - Michel Orrit
- LION, Huygens-Kamerlingh
Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2300RA Leiden, The Netherlands
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8
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de Magalhães CET, Savedra RML, Dias KS, Ramos R, Siqueira MF. Structural dependence of MEH-PPV chromism in solution. J Mol Model 2017; 23:91. [PMID: 28236031 DOI: 10.1007/s00894-017-3239-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 01/13/2017] [Indexed: 11/24/2022]
Abstract
The chromism observed in the MEH-PPV polymer in tetrahydrofuran (THF) solution is discussed as a function of the structural morphology of the backbone chains. To evaluate this phenomenon, we carried out simulations employing a hybrid methodology using molecular dynamics and quantum mechanical approaches. Our results support the hypothesis that the morphological order-disorder transition is related to the change from red to blue phase observed experimentally. The morphological disorder is associated with total or partial twisted arrangements in the polymer backbone, which induces an electronic conjugation length more confined to shorter segments. In addition, the main band of the MEH-PPV UV-Vis spectrum at the lower wavelength is related to the blue phase, in contrast to the red phase found for the more planar backbone chains.
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Affiliation(s)
- Carlos E T de Magalhães
- Laboratório de Simulação Molecular de Materiais, Departamento de Física, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, CEP 35400-000 Ouro, Preto-MG, Brazil
| | - Ranylson M L Savedra
- Laboratório de Simulação Molecular de Materiais, Departamento de Física, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, CEP 35400-000 Ouro, Preto-MG, Brazil
- Laboratório de Polímeros e Propriedades Eletrônicas de Materiais, Departamento de Física, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, 35400-000, Ouro Preto-MG, Brazil
| | - Karina S Dias
- Laboratório de Simulação Molecular de Materiais, Departamento de Física, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, CEP 35400-000 Ouro, Preto-MG, Brazil
| | - Rodrigo Ramos
- Instituto de Física, Universidade de São Paulo, Rua do Matão s/n, trav. R 187, São Paulo-SP, Brazil
| | - Melissa F Siqueira
- Laboratório de Simulação Molecular de Materiais, Departamento de Física, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, CEP 35400-000 Ouro, Preto-MG, Brazil.
- Laboratório de Polímeros e Propriedades Eletrônicas de Materiais, Departamento de Física, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, 35400-000, Ouro Preto-MG, Brazil.
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9
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Hader K, Consani C, Brixner T, Engel V. Mapping of exciton–exciton annihilation in MEH-PPV by time-resolved spectroscopy: experiment and microscopic theory. Phys Chem Chem Phys 2017; 19:31989-31996. [DOI: 10.1039/c7cp05168a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transient absorption traces taken on samples of the polymer MEH-PPV are measured as a function of the laser intensity.
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Affiliation(s)
- Kilian Hader
- Institut für Physikalische und Theoretische Chemie
- Universität Würzburg
- 97074 Würzburg
- Germany
| | - Cristina Consani
- Institut für Physikalische und Theoretische Chemie
- Universität Würzburg
- 97074 Würzburg
- Germany
- Center for Nanosystems Chemistry (CNC)
| | - Tobias Brixner
- Institut für Physikalische und Theoretische Chemie
- Universität Würzburg
- 97074 Würzburg
- Germany
- Center for Nanosystems Chemistry (CNC)
| | - Volker Engel
- Institut für Physikalische und Theoretische Chemie
- Universität Würzburg
- 97074 Würzburg
- Germany
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10
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Wise AJ, Grey JK. Understanding the Structural Evolution of Single Conjugated Polymer Chain Conformers. Polymers (Basel) 2016; 8:polym8110388. [PMID: 30974664 PMCID: PMC6432208 DOI: 10.3390/polym8110388] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 10/23/2016] [Accepted: 10/31/2016] [Indexed: 12/03/2022] Open
Abstract
Single molecule photoluminescence (PL) spectroscopy of conjugated polymers has shed new light on the complex structure–function relationships of these materials. Although extensive work has been carried out using polarization and excitation intensity modulated experiments to elucidate conformation-dependent photophysics, surprisingly little attention has been given to information contained in the PL spectral line shapes. We investigate single molecule PL spectra of the prototypical conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) which exists in at least two emissive conformers and can only be observed at dilute levels. Using a model based on the well-known “Missing Mode Effect” (MIME), we show that vibronic progression intervals for MEH-PPV conformers can be explained by relative contributions from particular skeletal vibrational modes. Here, observed progression intervals do not match any ground state Raman active vibrational frequency and instead represent a coalescence of multiple modes in the frequency domain. For example, the higher energy emitting “blue” MEH-PPV form exhibits PL maxima at ~18,200 cm−1 with characteristic MIME progression intervals of ~1200–1350 cm−1, whereas the lower energy emitting “red” form peaks at ~17,100 cm−1 with intervals in the range of ~1350–1450 cm−1. The main differences in blue and red MEH-PPV chromophores lie in the intra-chain order, or, planarity of monomers within a chromophore segment. We demonstrate that the Raman-active out-of-plane C–H wag of the MEH-PPV vinylene group (~966 cm−1) has the greatest influence in determining the observed vibronic progression MIME interval. Namely, larger displacements (intensities)—indicating lower intra-chain order—lower the effective MIME interval. This simple model provides useful insights into the conformational characteristics of the heterogeneous chromophore landscape without requiring costly and time-consuming low temperature or single molecule Raman capabilities.
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Affiliation(s)
- Adam J Wise
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA.
| | - John K Grey
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA.
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11
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Grußmayer KS, Steiner F, Lupton JM, Herten DP, Vogelsang J. Differentiation between Shallow and Deep Charge Trap States on Single Poly(3-hexylthiophene) Chains through Fluorescence Photon Statistics. Chemphyschem 2015; 16:3578-83. [DOI: 10.1002/cphc.201500719] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Indexed: 01/19/2023]
Affiliation(s)
- Kristin S. Grußmayer
- CellNetworks Cluster und Physikalisch-Chemisches Institut; Universität Heidelberg; Im Neuenheimer Feld 267 69210 Heidelberg Germany
| | - Florian Steiner
- Institut für Experimentelle und Angewandte Physik; Universität Regensburg; Universitätsstrasse 31 93053 Regensburg Germany
| | - John M. Lupton
- Institut für Experimentelle und Angewandte Physik; Universität Regensburg; Universitätsstrasse 31 93053 Regensburg Germany
| | - Dirk-Peter Herten
- CellNetworks Cluster und Physikalisch-Chemisches Institut; Universität Heidelberg; Im Neuenheimer Feld 267 69210 Heidelberg Germany
| | - Jan Vogelsang
- Institut für Experimentelle und Angewandte Physik; Universität Regensburg; Universitätsstrasse 31 93053 Regensburg Germany
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12
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Consani C, Koch F, Panzer F, Unger T, Köhler A, Brixner T. Relaxation dynamics and exciton energy transfer in the low-temperature phase of MEH-PPV. J Chem Phys 2015; 142:212429. [DOI: 10.1063/1.4918645] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- Cristina Consani
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Federico Koch
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Fabian Panzer
- Lehrstuhl Experimentalphysik II, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
| | - Thomas Unger
- Lehrstuhl Experimentalphysik II, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
| | - Anna Köhler
- Lehrstuhl Experimentalphysik II, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
| | - Tobias Brixner
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Center for Nanosystems Chemistry (CNC), Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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13
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Single Molecule Studies of a Ladder Type Conjugated Polymer: Vibronic Spectra, Line Widths, and Energy Transfer. Macromol Rapid Commun 2015; 36:1096-102. [DOI: 10.1002/marc.201400739] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 02/25/2015] [Indexed: 11/07/2022]
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14
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Tian Y, Kuzimenkova MV, Halle J, Wojdyr M, Diaz de Zerio Mendaza A, Larsson PO, Müller C, Scheblykin IG. Molecular Weight Determination by Counting Molecules. J Phys Chem Lett 2015; 6:923-927. [PMID: 26262846 DOI: 10.1021/acs.jpclett.5b00296] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Molecular weight (MW) is one of the most important characteristics of macromolecules. Sometimes, MW cannot be measured correctly by conventional methods like gel permeation chromatography (GPC) due to, for example, aggregation. We propose using single-molecule spectroscopy to measure the average MW simply by counting individual fluorescent molecules embedded in a thin matrix film at known mass concentration. We tested the method on dye molecules, a labeled protein, and the conjugated polymer MEH-PPV. We showed that GPC with polystyrene calibration overestimates the MW of large MEH-PPV molecules by 40 times due to chain aggregation and stiffness. This is a crucial observation for understanding correlations between the conjugated polymer length, photophysics and performances of devices. The method can measure the MW of fluorescent molecules, biological objects, and nanoparticles at ultimately low concentrations and does not need any reference; it is conformation-independent and has no limitations regarding the detected MW range.
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Affiliation(s)
| | | | | | | | - Amaia Diaz de Zerio Mendaza
- §Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | | | - Christian Müller
- §Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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15
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Yang J, Ham S, Kim TW, Park KH, Nakao K, Shimizu H, Iyoda M, Kim D. Inhomogeneity in the excited-state torsional disorder of a conjugated macrocycle. J Phys Chem B 2015; 119:4116-26. [PMID: 25700008 DOI: 10.1021/jp5123689] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The photophysics of conjugated polymers has generally been explained based on the interactions between the component conjugated chromophores in a tangled chain. However, conjugated chromophores are entities with static and dynamic structural disorder, which directly affects the conjugated polymer photophysics. Here we demonstrate the impact of chain structure torsional disorder on the spectral characteristics for a macrocyclic oligothiophene 1, which is obscured in conventional linear conjugated chromophores by diverse structural disorders such as those in chromophore size and shape. We used simultaneous multiple fluorescence parameter measurement for a single molecule and quantum-mechanical calculations to show that within the fixed conjugation length across the entire ring an inhomogeneity from torsional disorder in the structure of 1 plays a crucial role in causing its energetic disorder, which affords the spectral broadening of ∼220 meV. The torsional disorder in 1 fluctuated on the time scale of hundreds of milliseconds, typically accompanied by spectral drifts on the order of ∼10 meV. The fluctuations could generate torsional defects and change the electronic structure of 1 associated with the ring symmetry. These findings disclose the fundamental nature of conjugated chromophore that is the most elementary spectroscopic unit in conjugated polymers and suggest the importance of engineering structural disorder to optimize polymer-based device photophysics. Additionally, we combined defocused wide-field fluorescence microscopy and linear dichroism obtained from the simultaneous measurements to show that 1 emits polarized light with a changing polarization direction based on the torsional disorder fluctuations.
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Affiliation(s)
- Jaesung Yang
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University , Seoul 120-749, Korea
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16
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Adachi T, Vogelsang J, Lupton JM. Unraveling the Electronic Heterogeneity of Charge Traps in Conjugated Polymers by Single-Molecule Spectroscopy. J Phys Chem Lett 2014; 5:573-577. [PMID: 26276611 DOI: 10.1021/jz402621y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Charge trapping is taken for granted in modeling the characteristics of organic semiconductor devices, but very few techniques actually exist to spectroscopically pinpoint trap states. For example, trap levels are often assumed to be discrete in energy. Using the well-known keto defect in polyfluorene as a model, we demonstrate how single-molecule spectroscopy can directly track the formation of charge and exciton traps in conjugated polymers in real time, providing crucial information on the energetic distribution of trap sites relative to the polymer optical gap. Charge traps with universal spectral fingerprints scatter by almost 1 eV in depth, implying that substantial heterogeneity must be taken into account when modeling devices.
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Affiliation(s)
- Takuji Adachi
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Jan Vogelsang
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - John M Lupton
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
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17
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Yamagata H, Hestand NJ, Spano FC, Köhler A, Scharsich C, Hoffmann ST, Bässler H. The red-phase of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV): A disordered HJ-aggregate. J Chem Phys 2013; 139:114903. [DOI: 10.1063/1.4819906] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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18
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Lee P, Li WC, Chen BJ, Yang CW, Chang CC, Botiz I, Reiter G, Lin TL, Tang J, Yang ACM. Massive enhancement of photoluminescence through nanofilm dewetting. ACS NANO 2013; 7:6658-6666. [PMID: 23888931 DOI: 10.1021/nn4009752] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Due to the rather low efficiencies of conjugated polymers in solid films, their successful applications are scarce. However, recently several experiments indicated that a proper control of molecular conformations and stresses acting on the polymers may provide constructive ways to boost efficiency. Here, we report an amazingly large enhancement of photoluminescence as a consequence of strong shear forces acting on the polymer chains during nanofilm dewetting. Such sheared chains exhibited an emission probability many times higher than the nonsheared chains within a nondewetted film. This increase in emission probability was accompanied by the emergence of an additional blue-shifted emission peak, suggesting reductions in conjugation length induced by the dewetting-driven mass redistribution. Intriguingly, exciton quenching on narrow-band-gap substrates was also reduced, indicating suppression of vibronic interactions of excitons. Dewetting and related shearing processes resulting in enhanced photoluminescence efficiency are compatible with existing fabrication methods of polymer-based diodes and solar cells.
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Affiliation(s)
- Peiwei Lee
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan
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19
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Camacho R, Thomsson D, Sforazzini G, Anderson HL, Scheblykin IG. Inhomogeneous Quenching as a Limit of the Correlation Between Fluorescence Polarization and Conformation of Single Molecules. J Phys Chem Lett 2013; 4:1053-1058. [PMID: 26291377 DOI: 10.1021/jz400142x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The photophysical properties of conjugated polymers (CPs) largely depend on the interactions between the CP and its environment. We present a study of two polymers with identical conjugated backbones, bare and insulated, that showed different fluorescence excitation modulation depth histograms. However, the polarization differences are not related to differences in conformation, as commonly believed, but to the existence of "dark" chromophores in the bare polymer that are statically quenched. This results in inhomogeneous quenching of the polymer chain that breaks the correlation between excitation fluorescence polarization and conjugated polymer chain conformation.
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Affiliation(s)
- Rafael Camacho
- †Chemical Physics, Lund University, Box 124 22100, Lund, Sweden
| | - Daniel Thomsson
- †Chemical Physics, Lund University, Box 124 22100, Lund, Sweden
| | - Giuseppe Sforazzini
- ‡Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Harry L Anderson
- ‡Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, United Kingdom
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20
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Bolinger JC, Traub MC, Brazard J, Adachi T, Barbara PF, Vanden Bout DA. Conformation and energy transfer in single conjugated polymers. Acc Chem Res 2012; 45:1992-2001. [PMID: 22775295 DOI: 10.1021/ar300012k] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In contrast to the detailed understanding of inorganic materials, researchers lack a comprehensive view of how the properties of bulk organic materials arise from their individual components. For conjugated polymers to eventually serve as low cost semiconductor layers in electronic devices, researchers need to better understand their functionality. For organics, traditional materials science measurements tend to destroy the species of interest, especially at low concentrations. However, fluorescence continues to be a remarkably flexible, relatively noninvasive tool for probing the properties of individual molecules and allows researchers to carry out a broad range of experiments based on a relatively simple concept. In addition, the sensitivity of single-molecule spectroscopy allows researchers to see the properties of an individual component that would be masked in the bulk phase. In this Account, we examine several photophysical properties of different conjugated polymers using single-molecule spectroscopy. In these experiments, we probed the relationship between the conformation of single conjugated polymer chains and the distance scale and efficiency of energy transfer within the polymer. Recent studies used polarization anisotropy measurements on single polymer chains to study chain folding following spin-casting from solution. This Account summarizes the effects of monomer regioregularity and backbone rigidity, by comparing a regiorandom phenylene vinylene (MEH-PPV) with both a regiorandom and regioregular thiophene (P3HT). Synthesis of novel polymers allowed us to explore the role of different conformation-directing inclusions in a PPV backbone. We showed that these inclusions control the conformation of individual chains and that molecular dynamics can predict these structural effects. In situ solvent vapor annealing studies explored the dynamics of polymer chains as well as the effect of solvent evaporation on the structural equilibrium of the polymer. We observed that a slower rate of solvent evaporation results in a narrow population of highly ordered polymer chains. These highly ordered single chains serve as a model system to probe the effect of conformation on energy transfer following excitation in single MEH-PPV polymer chains in two distinct experiments. In the first, we correlated the anisotropy of the fluorescence emission of individual chains with the anisotropy of their fluorescence excitation. Using this data, we derived a model for energy transfer in a conjugated polymer, simulating chromophores along a chain, coupled via Förster energy transfer. In the second experiment, super-resolution measurements demonstrated the ability of single-molecule spectroscopy to directly visualize energy transfer along a polymer chain embedded in a model device environment. A capacitive device allowed for controlled localization of hole polarons onto the polymer chain. These positive charges subsequently quenched local excitations, providing insight into the range of energy transfer in these single polymer molecules. As researchers continue to characterize conjugated polymer films and develop methods for creating multichain systems, single-molecule techniques will provide a greater understanding of how polymer morphology influences interchain interactions and will lead to a richer description of the electronic properties of bulk conjugated polymer films.
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21
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Camacho R, Thomsson D, Yadav D, Scheblykin I. Quantitative characterization of light-harvesting efficiency in single molecules and nanoparticles by 2D polarization microscopy: Experimental and theoretical challenges. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.03.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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Köhler A, Hoffmann ST, Bässler H. An Order–Disorder Transition in the Conjugated Polymer MEH-PPV. J Am Chem Soc 2012; 134:11594-601. [DOI: 10.1021/ja302408a] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anna Köhler
- Organic Semiconductors, Experimental Physics II, Department
of Physics and Bayreuth Institute of Macromolecular Science(BIMF), University of Bayreuth, Bayreuth 95440, Germany
| | - Sebastian T. Hoffmann
- Organic Semiconductors, Experimental Physics II, Department
of Physics and Bayreuth Institute of Macromolecular Science(BIMF), University of Bayreuth, Bayreuth 95440, Germany
| | - Heinz Bässler
- Organic Semiconductors, Experimental Physics II, Department
of Physics and Bayreuth Institute of Macromolecular Science(BIMF), University of Bayreuth, Bayreuth 95440, Germany
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23
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Marques AT, Burrows HD, Seixas de Melo JS, Valente AJM, Justino LLG, Scherf U, Fron E, Rocha S, Hofkens J, Snedden EW, Monkman AP. Spectroscopic properties, excitation, and electron transfer in an anionic water-soluble poly(fluorene-alt-phenylene)-perylenediimide copolymer. J Phys Chem B 2012; 116:7548-59. [PMID: 22554070 DOI: 10.1021/jp3000703] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
An anionic fluorene-phenylene poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}-based copolymer containing on-chain perylenediimine (PDI) chromophoric units, PBS-PFP-PDI, was synthesized and its photophysical properties studied as aggregates and isolated chains in water and dioxane/water (1:1) solution. UV-vis and emission spectroscopy measurements, time-correlated single photon counting, and wide field imaging have been employed to investigate the excited-state behavior of the PBS-PFP-PDI copolymer, including the effect of environment on the energy and electron transfer to the on-chain PDI chromophore. Although the Förster overlap integral is favorable, no evidence is found for intramolecular singlet excitation energy transfer in isolated copolymer chains in solution. Fluorescence is suggested to involve an interchain process, thus revealing that isolated copolymer chains in solution do not undergo efficient intramolecular energy transfer. However, quenching of the PBS-PFP excited state by PDI is observed in aqueous media and ultrafast pump-probe studies in water or dioxane-water solutions show that electron transfer occurs from the phenylene-fluorene units to the PDI. The extent of electron transfer increases with aggregation, suggesting it is largely an interchain process. The interaction of the negatively charged PBS-PFP-PDI copolymer with the positively charged surfactant hexadecyltrimethylammonium bromide (CTAB) in solution has also been studied. The copolymer PBS-PFP-PDI aggregates with the surfactant already at concentrations below the critical micelle concentration (cmc) and the nonpolar environment allows intermolecular energy transfer, observed by the weak emission band located at 630 nm that is associated with the emission of the PDI chromophore. However, the fact that the PDI photoluminescence (PL) lifetime (~1.4 ns) obtained in the presence of CTAB is considerably shorter than that of the nonaggregated chromophore (~5.4 ns) suggests that even in this case there is considerable PL quenching, possibly through some charge transfer route. The increase of the PBS-PFP-PDI photoluminescence intensity at surfactant concentrations above the cmc indicates deaggregation of polyelectrolyte within the initially formed polyelectrolyte-surfactant aggregates.
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Affiliation(s)
- Ana T Marques
- Department of Chemistry, University of Coimbra, P3004-535 Coimbra, Portugal.
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24
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Vogelsang J, Lupton JM. Solvent Vapor Annealing of Single Conjugated Polymer Chains: Building Organic Optoelectronic Materials from the Bottom Up. J Phys Chem Lett 2012; 3:1503-1513. [PMID: 26285629 DOI: 10.1021/jz300294m] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Optoelectronic devices based on organic materials show a strong relationship between the morphological structure of the material and the function of the device. One of the grand challenges in improving the efficiencies of these devices is hence achieving morphological control throughout the entire course of processing. One of the most important postprocessing methods is solvent vapor annealing, which has repeatedly demonstrated its utility in improving the efficiency of organic-material-based devices by changing bulk-film morphology. This Perspective discusses the recent impact of single-molecule spectroscopy techniques in unraveling morphological changes and molecular dynamics and presents solvent vapor annealing as a tool to build organic optoelectronic materials from the bottom up. In particular, we discuss examples of how solvent vapor annealing at the single-chain level can be split into two different regimes, (i) the solvation regime, in which intrachain interactions and molecular dynamics during solvent vapor annealing can be probed, and (ii) the aggregation regime, in which the influence of interchain interactions can be probed. Finally, it will be shown that solvent vapor annealing in the aggregation regime can be used to build highly ordered mesoscopic objects with distinct properties such as long-range energy transfer.
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Affiliation(s)
- Jan Vogelsang
- §Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - John M Lupton
- §Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
- †Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
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25
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Osad'ko IS, Shchukina AL. Blinking fluorescence of single donor-acceptor pairs: important role of "dark'' states in resonance energy transfer via singlet levels. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061907. [PMID: 23005127 DOI: 10.1103/physreve.85.061907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 03/23/2012] [Indexed: 06/01/2023]
Abstract
The influence of triplet levels on Förster resonance energy transfer via singlet levels in donor-acceptor (D-A) pairs is studied. Four types of D-A pair are considered: (i) two-level donor and two-level acceptor, (ii) three-level donor and two-level acceptor, (iii) two-level donor and three-level acceptor, and (iv) three-level donor and three-level acceptor. If singlet-triplet transitions in a three-level acceptor molecule are ineffective, the energy transfer efficiency E=I_{A}/(I_{A}+I_{D}), where I_{D} and I_{A} are the average intensities of donor and acceptor fluorescence, can be described by the simple theoretical equation E(F)=FT_{D}/(1+FT_{D}). Here F is the rate of energy transfer, and T_{D} is the donor fluorescence lifetime. In accordance with the last equation, 100% of the donor electronic energy can be transferred to an acceptor molecule at FT_{D}≫1. However, if singlet-triplet transitions in a three-level acceptor molecule are effective, the energy transfer efficiency is described by another theoretical equation, E(F)=F[over ¯](F)T_{D}/[1+F[over ¯](F)T_{D}]. Here F[over ¯](F) is a function of F depending on singlet-triplet transitions in both donor and acceptor molecules. Expressions for the functions F[over ¯](F) are derived. In this case the energy transfer efficiency will be far from 100% even at FT_{D}≫1. The character of the intensity fluctuations of donor and acceptor fluorescence indicates which of the two equations for E(F) should be used to find the value of the rate F. Therefore, random time instants of photon emission in both donor and acceptor fluorescence are calculated by the Monte Carlo method for all four types of D-A pair. Theoretical expressions for start-stop correlators (waiting time distributions) in donor and acceptor fluorescence are derived. The probabilities w_{N}^{D}(t) and w_{N}^{A}(t) of finding N photons of donor and acceptor fluorescence in the time interval t are calculated for various values of the energy transfer rate F and for all four types of D-A pair. Comparison of the calculated D and A fluorescence trajectories with those measured by Weiss and co-workers proves the important role of triplet levels in energy transfer via singlet levels.
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Affiliation(s)
- I S Osad'ko
- Institute for Spectroscopy, RAS, Troitsk, Russia
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26
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Kobayashi H, Onda S, Furumaki S, Habuchi S, Vacha M. A single-molecule approach to conformation and photophysics of conjugated polymers. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2011.11.064] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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27
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Traub MC, Vogelsang J, Plunkett KN, Nuckolls C, Barbara PF, Vanden Bout DA. Unmasking bulk exciton traps and interchain electronic interactions with single conjugated polymer aggregates. ACS NANO 2012; 6:523-529. [PMID: 22208575 DOI: 10.1021/nn203860u] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
For conjugated polymer materials, there is currently a major gap in understanding between the fundamental properties observed in single molecule measurements and the bulk electronic properties extracted from measurements of highly heterogeneous thin films. New materials and methodologies are needed to follow the evolution from single chain to bulk film properties as multiple chains begin to interact. In this work, we used a controlled solvent vapor annealing process to assemble single chains of phenylene-vinylene conjugated polymers into aggregates that can be individually spectroscopically interrogated. This approach allowed us to probe the effects of interchain coupling in isolated conjugated polymer nanodomains of controlled size. By assembling these aggregates from building blocks of both pristine MEH-PPV and MEH-PPV derivatives containing structure-directing ortho- or para-terphenyl inclusions, we were able to control the ordering of these nanodomains as measured by single aggregate polarization anisotropy measurments. Depending on the individual chain constituents, these aggregates varied from highly anisotropic to nearly isotropic, respectively facilitating or inhibiting interchain coupling. From the single chain fluorescence lifetimes, we demonstrated that these structure directing inclusions effectively break the phenylene-vinylene conjugation, allowing us to differentiate interchain electronic effects from those due to hyper-extended conjugation. We observed well-defined bathochromic shifts in the fluorescence spectra of the aggregates containing extensive interchain interactions, indicating that low-energy exciton traps in MEH-PPV are the result of coupling interactions between neighboring chain segments. These results demonstrate the power of the synthetic inclusion approach to control properties at not just the single chain level, but as a comprehensive approach toward ground-up design of bulk electronic properties.
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Affiliation(s)
- Matthew C Traub
- Department of Chemistry and Biochemistry and the Center for Nano and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712, USA
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28
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Kobayashi H, Tsuchiya K, Ogino K, Vacha M. Spectral multitude and spectral dynamics reflect changing conjugation length in single molecules of oligophenylenevinylenes. Phys Chem Chem Phys 2012; 14:10114-8. [DOI: 10.1039/c2cp41509g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Lupton JM. Chromophores in Conjugated Polymers-All Straight? Chemphyschem 2011; 13:901-7. [DOI: 10.1002/cphc.201100770] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Indexed: 11/10/2022]
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30
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Traub MC, Lakhwani G, Bolinger JC, Bout DV, Barbara PF. Electronic Energy Transfer in Highly Aligned MEH-PPV Single Chains. J Phys Chem B 2011; 115:9941-7. [DOI: 10.1021/jp204591p] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew C. Traub
- Center for Nano and Molecular Science and Technology and §Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, United States
| | - Girish Lakhwani
- Center for Nano and Molecular Science and Technology and §Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, United States
| | - Joshua C. Bolinger
- Center for Nano and Molecular Science and Technology and §Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, United States
| | - David Vanden Bout
- Center for Nano and Molecular Science and Technology and §Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, United States
| | - Paul F. Barbara
- Center for Nano and Molecular Science and Technology and §Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, United States
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