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

Abstract

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.

Tailoring Nanoscale Morphology of Polymer:Fullerene Blends Using Electrostatic Field

“…Again, linecuts shown in Figure S2b of the (100) peak display reduced fwhm of 20.1 ± 0.16° for films exposed to vertical E-field compared to the control (25.8 ± 0.19°), horizontal (26 ± 0.24°) and tilted (25.7 ± 0.83°) cases. Our published work on fluorescence and Raman measurements affirms our GIWAXS results that the static forces of E-field induce anisotropic orientation in P3HT-only thin films. So far, we showed that E-field plays critical role in tailoring the surface morphology and phase distribution in P3HT-PCBM BHJ.…”

“…Again, linecuts shown in FigureS2bof the (100) peak display reduced fwhm of 20.1 ± 0.16°for films exposed to vertical E-field compared to the control (25.8 ± 0.19°), horizontal (26 ± 0.24°) and tilted (25.7 ± 0.83°) cases. Our published work on fluorescence and Raman measurements47…”

Langmuir-Schaefer films of regioregular polythiophene derivatives as VOCs sensors

“…These results are in agreement with the parameters of molecular ordering of the P3HT and P3OT LS films before and after gas exposure ( Table 2). Differences in the values of I C-C /I C=C and FWHM of C=C mode found for the LS film of P3HT before and after gas exposure confirm that the morphology of this film was more affected than the LS film of P3OT, resulting in higher molecular disorder [44] which represents a limitation to the carrier mobility in polymer matrices [45,46].…”