Abstract
The electrical properties of α-quaterthiophene, α-hexathiophene, and pentacene single crystals have been studied for low iodine dopant concentrations. The electronic and ionic currents have been separated experimentally, providing quantitative information on the ion mobility. The mobility of the ions in these layered structures is strongly anisotropic. Parallel to the molecular layers the mobility is of order of to whereas perpendicular to the layers it is smaller by about 4 orders of magnitude. In addition, the activation energy for diffusion parallel to the layers is also much smaller (0.2–0.3 eV) than for diffusion perpendicular to the layers (0.85 eV).
- Received 27 September 1999
DOI:https://doi.org/10.1103/PhysRevB.61.10803
©2000 American Physical Society