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How Do Disorder, Reorganization, and Localization Influence the Hole Mobility in Conjugated Copolymers?

  • In order to unravel the intricate interplay between disorder effects, molecular reorganization, and charge carrier localization, a comprehensive study was conducted on hole transport in a series of conjugated alternating phenanthrene indenofluorene copolymers. Each polymer in the series contained one further comonomer comprising monoamines, diamines, or amine-free structures, whose influence on the electronic, optical, and charge transport properties was studied. The series covered a wide range of highest occupied molecular orbital (HOMO) energies as determined by cyclovoltammetry. The mobility, inferred from time-of-flight (ToF) experiments as a function of temperature and electric field, was found to depend exponentially on the HOMO energy. Since possible origins for this effect include energetic disorder, polaronic effects, and wave function localization, the relevant parameters were determined using a range of methods. Disorder and molecular reorganization were established first by an analysis of absorption and emissionIn order to unravel the intricate interplay between disorder effects, molecular reorganization, and charge carrier localization, a comprehensive study was conducted on hole transport in a series of conjugated alternating phenanthrene indenofluorene copolymers. Each polymer in the series contained one further comonomer comprising monoamines, diamines, or amine-free structures, whose influence on the electronic, optical, and charge transport properties was studied. The series covered a wide range of highest occupied molecular orbital (HOMO) energies as determined by cyclovoltammetry. The mobility, inferred from time-of-flight (ToF) experiments as a function of temperature and electric field, was found to depend exponentially on the HOMO energy. Since possible origins for this effect include energetic disorder, polaronic effects, and wave function localization, the relevant parameters were determined using a range of methods. Disorder and molecular reorganization were established first by an analysis of absorption and emission measurements and second by an analysis of the ToF measurements. In addition, density functional theory calculations were carried out to determine how localized or delocalized holes on a polymer chain are and to compare calculated reorganization energies with those that have been inferred from optical spectra. In summary, we conclude that molecular reorganization has little effect on the hole mobility in this system while both disorder effects and hole localization in systems with low-lying HOMOs are predominant. In particular, as the energetic disorder is comparable for the copolymers, the absolute value of the hole mobility at room temperature is determined by the hole localization associated with the triarylamine moieties.‚Ķshow moreshow less

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Metadaten
Author:Sebastian T. Hoffmann, Frank Jaiser, Anna Hayer, Heinz Baessler, Thomas Unger, Stavros Athanasopoulos, Dieter NeherORCiDGND, Anna Koehler
DOI:https://doi.org/10.1021/ja308820j
ISSN:0002-7863 (print)
Parent Title (English):JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Publisher:AMER CHEMICAL SOC
Place of publication:WASHINGTON
Document Type:Article
Language:English
Year of first Publication:2013
Year of Completion:2013
Release Date:2017/03/26
Volume:135
Issue:5
Pagenumber:11
First Page:1772
Last Page:1782
Funder:Bundesministerium fur Bildung und Forschung (BMBF project "NEMO") [FKZ 13N10622, FKZ 13N10614]; Photophysics of Synthetic and Biological Multichromophoric Systems of the German science foundation (DFG) [GRK 1640]