Vibrational Neutron Scattering Spectra for Undoped and Doped P3HT

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.