Flexible poly (3, 3″″″- dialkylquaterthiophene) based interdigitated metal-semiconductor-metal ammonia gas sensor

Abstract

In this article, poly (3, 3′′′- dialkylquaterthiophene) (PQT-12) thin film based interdigitated metal-semiconductor-metal (MSM) is fabricated by a spin coating method on flexible polyamide substrate for ammonia (NH3) gas sensing applications possibly for the first time. The average roughness, root mean square roughness, peak-to-peak spacing, average grain size, and grain length are measured as 0.6, 0.7, 6.4, 32.1, and 53.4 nm, respectively by atomic force microscopy for the PQT-12 film. These results clearly confirm the formation of a very smooth film on polyamide substrate to be explored for the gas sensing applications. Further, the scanning electron microscopy, fourier transform infrared spectroscopy, and cyclic voltammetry measurements have been done to investigate the effect of ammonia gas on the PQT-12 thin film. The resistance of the sensor is increased with the ammonia gas concentration as a result we get a very good response of 8.6% at 100 ppm with a detection limit of 300 ppb. The fabricated sensor exhibits a response time of 8 s and recovery time of 103 s. The sensor is tested for real-time ammonia sensing in the ambient environment using low-cost electronic circuits to demonstrate its fast response. © 2017 Elsevier B.V.