Doping effect upon the molecular order of thin films of conducting polymers

Based in a linear dichroism analysis in the infrared region, we present a p reliminary investigation of the effect of FeCl3 doping upon the molecular o rder of Langmuir-Blodgett films prepared from mixtures of poly-hexadecylthi ophene (PHDT) and behenic acid (BA) at different relative concentrations. L ow values of gamma, the orientation angle of the alkyl chains relative to t he normal to the substrate, are normally associated to a higher degree of m olecular order. For pristine films, gamma is maximum at intermediate values of the relative concentrations of the mixtures. Upon doping, disorder incr eases and it is most noticeable in the more organized films.