Ammonia gas sensor based on pentacene organic field-effect transistor

Ammonia (NH ₃) sensors based on bottom contact organic field-effect transistors (OFETs) were created using pentacene as an active layer and polymerthylmethacrylate (PMMA) as an insulator. The OFET sensors exhibited a change in the electric characteristic such as the threshold voltage, the saturation current, and the field-effect charge carrier mobility when the sensors were exposed to different NH ₃ concentrations. Meanwhile, the favorable and rapid NH ₃ response characteristics of the OFET sensors were observed from the change in the drain-source current as a function of time, when the sensors were exposed to various cycles of exposure/evacuation of different NH ₃ concentrations ranging from 10 to 100 ppm. Moreover, the environmental stability of the OFET sensors to constantly detect the NH ₃ gas in air was studied by storing the sensors in air for 30 days.