Terahertz Mobility Measurements on P3HT Films: Device Comparison, Molecular Weight and Film Processing Effects
Okan Esenturk, Joseph S. Melinger
We report the first direct comparison of relative carrier mobilities in semiconducting organic polymer films measured using non-contact optical pump terahertz probe spectroscopy to those reported in electrical device studies. Relative transient signal amplitude measurements of photo-injected mobility as a function of polythiophene (P3HT) molecular weight correlate directly with electrical device test values, indicating that the THz method shows promise as a rapid materials screening approach. We also present new measurements on P3HT conducting films as a function of structural regularity, dispersing solvent, addition of C60 electron traps, sample temperature and other growth parameters relevant to device manufacture.