Förster Energy Transfer Studies of Polyelectrolyte Heterostructures Containing Conjugated Polymers:  A Means To Estimate Layer Interpenetration

Baur, Jeffery W.; Rubner, Michael F.; Reynolds, and John R.; Kim, Seung‐Ho

doi:10.1021/la981732w

Cited by 110 publications

(115 citation statements)

References 32 publications

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“…Therefore, complex gratings must be prepared to obtain films exhibiting Bragg peaks, even in neutron reflectivity studies 26,29,163,184,185,293,381,385,428) . This picture is supported by electrochemical studies 203,210) and by non-radiative energy transfer experiments 176,262) . But despite of the interdigitation of the oppositely charged polyelectrolytes, they are expected to decoil upon adsorption (cf.…”

Section: The Structure Of Polymer Films Made By Esamentioning

confidence: 79%

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

Bertrand

Jonas

Laschewsky³

et al. 2000

Macromol. Rapid Commun.

1,174

1,184

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A bit of historyThe key role of surfaces for many material properties as well as for many biological processes has been recognized now. Therefore, new strategies aim at the tailoring of the material's surface only -or of a thin surface layer, respectively -, while preserving the bulk properties of the underlying support. Particular emphasis has been given to the surface modification by polymers, in an attempt to extend the known versatility of polymer bulk materials to ultrathin films and coatings, and to prepare bulk-surface composite materials. The self-organization of polymers has been increasingly explored for the preparation of well-defined surfaces and interfaces in recent years, extending the use of the established methods of low molar mass compounds (for comparative reviews, see ref. 1-3)). With such techniques, polymer films are formed spontaneously on substrates, due to balanced interactions between substrate, polymer (or its precursor) and medium. Typically, very thin, often monomolecular layers are produced. Repetitive deposition steps provide a precise control over the total thickness of the coatings, in the range from a few angstroms up to the micrometer range. Moreover, the step-by-step procedures allow for a fine structuring in the third dimension. In addition to the preparation of uniform and homogeneous coatings, gratings, gradients or steps of defined height in molecular dimensions can be easily constructed.The most recent of the self-organization techniques is the alternating physisorption of oppositely charged polyelectrolytes, the so-called "layer-by-layer" method or "electrostatic self-assembly" (ESA) [3][4][5][6][7][8][9][10] . Although some early, singular studies of self-assembly by alternating adsorption of oppositely charged polyions are reported [11][12][13] , a practical method for ESA was developed Feature Article: The article presents the state-of-the-art of alternating physisorption of oppositely charged polyelectrolytes, the so-called "layer-by-layer" method or "electrostatic self-assembly" (ESA), for the preparation of thin polymer coatings. In comparison to other, more established self-organization techniques, this recent method is distinguished by its simplicity, versatility, and speed. In particular, the tendency for self-healing is unique. Emphasis is given to the role of the molecular structure of the polyelectrolytes, and to the nature of the support. Also, various parameters for the preparation of multilayer films are highlighted, which are very important due to the kinetic control of the build-up process. The structure of the resulting coatings, their quality and stability, chemical reactions in the films, and potential applications are discussed.Macromol. Rapid Commun. 21, No. 7

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Section: The Structure Of Polymer Films Made By Esamentioning

confidence: 79%

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

Bertrand

Jonas

Laschewsky³

et al. 2000

Macromol. Rapid Commun.

1,174

1,184

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“…Using other materials, such as conductive polymers [3][4][5], organic dyes [6], proteins, micelles, clays [7], and organic [8] or inorganic [9][10][11] particles, it is easy to fabricate hetero-structures. The electrical or optical properties [12] and energy transfer mechanism [13] have been reported. It can also be combined with other techniques [14], such as micro-printing [15,16] and the surface sol-gel method [17].…”

Section: Introductionmentioning

confidence: 99%

In situ observation of the initial adsorption process of layer‐by‐layer sequential adsorbed polyelectrolyte film using an AFM

Yamada

Shiratori

2002

Electrical Engineering Japan

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SUMMARYIn this study, we demonstrate the first observation results of the initial adsorption processes of polyelectrolytes to the substrate in solution by in situ observation using an AFM. The adsorption form of polyelectrolytes was changed by solution pH. It was found that the surface structure was controlled by adsorbing time of polyelectrolytes and strongly affected by both the previously formed under layer and the solution pH.

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“…Energy transfer for the geometrically relevant structures is many times more efficient than would be the case between two isolated chromophores. This relaxed distance dependence has been previously recog-nized for its importance in describing excitation transfer to metal films, [33][34][35] between dyes in layered Langmuir-Blodgett structures, [36][37][38][39] and in heterostructure OLEDs. [40] We recently reported device results using regioregular poly(3-hexylthiophene (RR-P3HT) as the energy donor and the low bandgap polymer poly(N-dodecyl-2,5,-bis(2′-thienyl)-pyrrole-2,1,3-benzothiadiazole) (PTPTB) [41,42] as the energy acceptor.…”

mentioning

confidence: 99%

Long‐Range Resonant Energy Transfer for Enhanced Exciton Harvesting for Organic Solar Cells

et al. 2007

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Exciton harvesting is of fundamental importance for the efficient operation of organic photovoltaic devices. The quantum efficiencies of many organic and hybrid organic-inorganic devices are still limited by low exciton harvesting efficiencies. This problem is most apparent in planar heterostructures that suffer from a direct tradeoff between light absorption and exciton harvesting. The bulk heterojunction concept [1,2] was designed to alleviate the problem of limited exciton migration by intimately blending the donor and acceptor phases on the nanometer length scale. In some polymer/fullerene systems, such as poly(2-methoxy,5-(3,7-dimethyloctyloxy)-1,4phenyl-enevinylene) (MDMO-PPV)/(6,6)-phenyl C61-butyric acid methyl ester (PCBM), time resolved spectroscopy shows the photoinduced formation of the radical anions and cations on femtosecond timescales. [3] This ultrafast formation of the polaron signature is only possible if every exciton is formed on a polymer chain segment that is immediately adjacent to one or more fullerene molecules. However, in other systems, very large domains prevail and, consequently, exciton harvesting is inefficient. [4] This has made the fabrication of efficient devices incorporating new materials difficult because each new material leads to a new morphology with its own characteristic length scale. The ordered bulk heterojunction architecture is intended to alleviate these issues by using a pre-patterned nanostructured scaffold [5][6][7] that has been engineered to have both straight pathways to the electrodes to ensure efficient carrier collection, and controlled domain size to ensure efficient exciton harvesting. Recently, chain alignment has been shown to be promoted for regioregular poly(3-hexyl thiophene) (RR-P3HT) in straight nanopores of anodic alumina leading to a 20-fold increase in hole-mobility in these structures.[8] For solar cell applications, higher mobilities reduce the effects of space charge [9] and increase the probability of separating the geminate pair formed immediately after exciton dissociation. [10][11][12][13] While the ordered bulk heterojunction architecture shows promise, existing structures have domains too large [14,15] for efficient exciton harvesting with singlet diffusion lengths only ca. 3-8 nm. [16][17][18] At this time, few alternatives other than nanostructuring have been proposed to increase exciton harvesting. Triplet excitons have been shown to have large diffusion lengths due to their long lifetimes, [18][19][20] but except in a few examples [21,22] this usually comes at the expense of a loss in energy of 0.4-0.8 eV associated with intersystem crossing between the photoexcited singlet to the first excited triplet. [23][24][25] At present, the direct engineering of singlet materials that have large diffusion lengths remains elusive due to the inherent disorder of most organic thin film materials. In this communication, we present theory and experiments that support a scheme to harvest singlet excitons over 25 nm away from the donor-acceptor int...

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Förster Energy Transfer Studies of Polyelectrolyte Heterostructures Containing Conjugated Polymers: A Means To Estimate Layer Interpenetration

Cited by 110 publications

References 32 publications

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

In situ observation of the initial adsorption process of layer‐by‐layer sequential adsorbed polyelectrolyte film using an AFM

Long‐Range Resonant Energy Transfer for Enhanced Exciton Harvesting for Organic Solar Cells

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