Ammonia gas detection using field-effect transistor based on a solution-processable organic semiconductor

We have developed a regioregular poly (3-hexylthiophene) (rr-P3HT) based organic field-effect transistor (OFET) for the detection of low concentration of ammonia (NH3) gas. The ammonia sensing mechanism of OFET based sensor device can be described in terms of the chemical interaction between NH3 and P3HT. Upon exposing the conducting channel to various concentrations of ammonia, a reduction in source-drain current/mobility, and an increase in threshold voltage were observed. This deterioration of the performance parameters of the OFET while exposing to different concentrations of ammonia was attributed to the dedoping effect. Our OFET based ammonia sensor could detect ammonia gas concentrations in the range 20 ppm-100 ppm. Moreover, the device showed excellent recovery to the initial state within a few minutes.