The response characteristics of a gas sensor based on poly-3-hexylithiophene thin-film transistors

Abstract This paper studies the response characteristics of a gas sensor for organic thin-film transistors (OTFTs), made from spin-coated poly-3-hexylthiophene (P3HT) on a thermally grown SiO 2 /Si wafer. The gas response characteristics of OTFT sensors are observed from the change in the drain–source current, as a function of time, when the P3HT-based OTFT sensors of different channel widths are exposed to cycles of exposure to and the evacuation of NH 3 gas, with concentration ranging from 10 to 100 ppm at room temperature in normal atmosphere. The measured drain–source current decreases rapidly with time after exposure to NH 3 gas and the response characteristics of the drain–source current are seen to be higher for larger values of NH 3 gas concentration. Also, the response characteristics of the OTFT sensor show that there is a shift in the threshold-voltage as well as a change in mobility after exposure to NH 3 gas.

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