Characterizing Electric Field Exposed P3HT Thin Films Using Polarized-Light Spectroscopies

P3HT (poly (3‐hexylthiophene)) has been widely used as a donor in the active layer in organic photovoltaic devices. Although moderately high‐power conversion efficiencies have been achieved with P3HT‐based devices, structural details, such as the orientation of polymer units and the extent of H‐ and...

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Bibliographic Details
Published in:Macromolecular chemistry and physics 2016-08, Vol.217 (16), p.1801-1809
Main Authors: Bhattacharjee, Ujjal, Elshobaki, Moneim, Santra, Kalyan, Bobbitt, Jonathan M., Chaudhary, Sumit, Smith, Emily A., Petrich, Jacob W.
Format: Article
Language:English
Subjects:
Anisotropy
Channels
electric field
Electric fields
Exposure
fluorescence anisotropy
Hole mobility
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
MATERIALS SCIENCE
Order disorder
Orientation
P3HT
Photovoltaic cells
photovoltaics
polarized Raman spectroscopy
Thin films
π-conjugated polymer
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Summary:P3HT (poly (3‐hexylthiophene)) has been widely used as a donor in the active layer in organic photovoltaic devices. Although moderately high‐power conversion efficiencies have been achieved with P3HT‐based devices, structural details, such as the orientation of polymer units and the extent of H‐ and J‐aggregation are not yet fully understood; and different measures have been taken to control the ordering in the material. One such measure, which has been exploited, is to apply an electric field from a Van de Graaff generator. Fluorescence (to measure anisotropy instead of polarization, which is more commonly measured) and Raman spectroscopy are used to characterize the order of P3HT molecules in thin films resulting from the field. Preferential orientations of the units in a thin film are determined, consistent with observed hole mobility in thin‐film transistors, and it is observed that the apparent H‐coupling strength changes when the films are exposed to oriented electrical fields during drying. A simple method of orienting poly (3‐hexylthiophene) (P3HT) polymers under a unipolar electrostatic field generated by a Van de Graaff dome is reported. Previous uses of electric field are limited to P3HT nanofibers and in microscopic channels. Excitation anisotropy is used to determine the orientation of P3HT which is corroborated by Polarized Raman and hole mobility measurements.
ISSN:1022-1352
1521-3935
DOI:10.1002/macp.201600113