Electronic properties of semiconducting poly(ferrocenylsilane) thin films with vapor-phase iodine diffusion doping

We report diffusion doping of the semiconducting polymer poly (ferrocenylsilanes), or PFS. We have obtained a steady-state conductivity change of greater than eight orders of magnitude effected through iodine vapor doping of PFS. The sign of thermoelectric power measurements indicates p-type conductivity. The conductivity exhibits an activation energy of DeltaE = (0.45-0.65) eV for moderately-doped samples and DeltaE = (0.8-0.99) eV for heavily-doped samples. We report sample photoconductivity, which we find to be principally of bolometric origin. We also study the evolution of electrical properties over time: during several days after fabrication, the samples exhibit an irreversible decrease in conductivity which may be attributable to partial iodine desorption. After this aging process, especially noticeable in heavily doped material, the sample properties stabilize, suggesting promise in a range of prospective device applications. (C) 2001 Kluwer Academic Publishers.