Morphology-Driven Sensitivity Enhancement in Organic Nanowire Chemiresistors

Chemiresistors were prepared from the common organic semiconductor, poly(3-hexylthiophene) (P3HT), which is known to respond to atmospheric humidity with an increase of its conductance. Chemiresistors with different P3HT morphologies were compared: a solution-cast film versus an organic nanowire 'mesh.' It was found that both types of chemiresistors show no response for an exposure to less than 50% relative humidity. When humidity exceeds this threshold, the conductance of both chemiresistors increases. The conductance response of the nanowire device is far stronger as compared to that of the solution-cast film. This difference can be justified by the much larger surface area in the nanowire morphology. We conclude that organic nanowires constitute a favourable morphology for organic sensor technology, and recommend their wider employment in organic sensor applications.