10.25338/B8HC7K
Harrelson, Thomas
0000-0002-8689-4273
University of California, Davis
Li, Jun
University of California, Davis
Moule, Adam
0000-0003-1354-3517
University of California, Davis
Vibrational Neutron Scattering Spectra for Undoped and Doped P3HT
Dryad
dataset
2018
2018-05-25T22:01:29Z
2018-05-25T22:01:29Z
en
1575625 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Doped semiconducting polymers have garnered vast research interest in
photovoltaic, transistor, thermoelectric, and sensor applications. P3HT is
a canonical semiconducting polymer that self-assembles into a mixture of
crystalline and amorphous domains. Doping P3HT can increase the observed
conductivity by several orders of magnitude. The vibrations of the polymer
are sensitive to the local morphology of the film, and the morphology of
the film changes upon doping. Vibrational neutron spectroscopy is a method
for identifying vibrational modes/phonons over a large energy range (1 meV
- 500 meV). Each peak in the spectra represents a specific vibrational
mode, which can be used to correlate local structure in the material. We
present spectra for undoped regioregular P3HT (rr-P3HT), undoped
regiorandom P3HT (rra-P3HT), undoped deuterated rr-P3HT, rr-P3HT doped
with F4TCNQ at 5% mole ratio, rr-P3HT doped with F4TCNQ at 17% mole ratio,
and rr-P3HT doped with I2 at 10% mole ratio.
The samples were coarse powders that were placed into the sample holder of
the neutron instrument. Thus, the resulting spectra are powder averages of
the vibrations. Most samples are not deuterated, which means that those
spectra are incoherent scattering spectra. The deuterated spectrum is
primarily coherent scattering, and should be treated differently. The data
was taken at the VISION spectrometer at the Spallation Neutron Source at
Oak Ridge National Laboratory. The data was collected by cooling the
sample to ~5 K, then opening the shutter allowing pulses of neutrons to
interact with the sample at known time points. Scattering neutrons hit the
analyzer crystals, which only reflect scattered neutrons with a known
wavelength toward the detector. The detector records the time at which a
scattered neutron hits the detector, allowing the energy loss of the
scattered neutron to be calculated through time-of-flight analysis. The
sample was run long enough to sufficiently reduce the signal to noise
ratio. The data is displayed in 3 columns: Energy loss (in meV),
Intensity, error. Most text file contains 2 sets of data: the first one is
the results from the forward scattering analyzers, the second from the
back scattering analyzers. The forward scattering data comes from low
momentum transfer scattering events, and the back scattering data comes
from high momentum transfer scattering events. If a text file contains
only one spectrum, it is the forward scattering data.