Nanostructure Dependence of Conductive Polymer Chemical Sensors

It is shown that the resistive sensing properties of conductive polymers are highly dependent on the material nanostructure. The sensing properties of regioregular poly(3-hexylthiophene) (P3HT) polymer thin films with porous nanofibrile structure, dense nanofibrile structure and nano-granular structure show very different conductance changes, in terms of both response amplitude and sign, upon exposure to various VOC vapors. This implies that multiple sensing mechanisms, such as both grain boundary and intra-grain effects, exist and the dominant sensing mechanism can vary with different material nanostructures. Possible mechanisms for these effects, and their correlation with observed material nanostructures, are also discussed.