Semicrystalline Structural Correlations of Conductivity in Conjugated Polymer Thin Films Surface-Doped by the Vapor Phase Method

π-Conjugated polymer (P3HT) thin films were surface-doped with fluoroalkyl trichlorosilane (FTS) by means of the vapor phase method. Semicrystalline structural changes as well as electronic properties, i.e., conductivity, carrier density, and carrier mobility, have been evaluated as a function of the amounts of FTS before and after surface-doping. The conductivity was quite enhanced by a factor of about 4 orders at the maximum, at which the carrier density was multiplied and the carrier mobility was reduced at the same time. It was found evidently that the increase in carrier density was due to the direct interaction between P3HT and FTS because of the electron transfer induced by the Lewis acidity of FTS. On the other hand, the decrease in carrier mobility was caused by disturbing and/or disordering the semicrystalline structure in P3HT during surface-doping of FTS.