Thickness changes in polythiophene gas sensors exposed to vapor

While gas sensors made from organic semiconductors such as polythiophene are attractive devices, little work has been made to understand or monitor the interaction of these sensors with the gas analyte molecules. In this work, we report in situ thickness changes in polythiophene films by monitoring the film thickness using X-ray reflectivity during exposure to gas vapors. This is the first time that the sensor–analyte interaction has been corroborated with physical changes in the film. We find the thickness change to be relatively small and to not depend strongly on the analyte concentration. We discuss the implications of these measurements, which advance the understanding of polymer based gas sensors.