Fabrication of gas sensor device using poly (3, 4-ethylenedioxythiophene)-poly (styrenesulfonate)-doped reduced graphene oxide organic thin films for detection of ammonia gas at room temperature

A low cost and simple method for fabrication of a gas sensor device was developed using reduced graphene oxide (rGO)-doped poly (3, 4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT-PSS) organic thin film for the detection of ammonia gas at room temperature. Scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photospectrometry and thermogravimetric analysis were used for the analysis of morphological, structural and thermal behavior of the prepared thin films. The doping of reduced graphene oxide in PEDOT-PSS was observed to increase the conductivity of pristine PEDOT-PSS thin films by threefold. The gas sensing mechanism of pure and doped PEDOT-PSS thin films were studied at room temperature by fabricating the sensor device on indium tin oxide-coated glass substrate. The gases such as ammonia, carbon monoxide, nitrogen dioxide and nitrogen were used to test the sensing performance in the prepared thin films. The reduced graphene oxide-doped PEDOT-PSS thin films show improved sensitivity towards all test gases, mainly toward ammonia gas with fast response and recovery times. The gas sensitivity of 10 wt% rGO-doped PEDOT-PSS thin film was observed to be about 87% for ammonia gas. The sensor stability test shows that, the prepared sensor is highly stable even after a period of 1 month. Due to improved sensitivity, stability and improved response and recovery times, these rGO-doped PEDOT-PSS organic thin films could be used to detect ammonia gas at low concentrations at room temperature.