Highly sensitive ethylene glycol-doped PEDOT–PSS organic thin films for LPG sensing

In this study, for the first time we report the fabrication of low-cost ethylene glycol (EG)-doped PEDOT–PSS (poly 3,4-ethylenedioxythiophene:polystyrene sulfonate) organic thin film sensors for the detection of LPG at room temperature. The prepared thin films were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy and thermogravimetric analysis (TGA) techniques for the analysis of their structural and morphological features. The doping of EG strongly improved the conductivity of pure PEDOT–PSS films by three orders of magnitude. The gas sensing responses of pristine and doped PEDOT–PSS thin films were investigated at room temperature by fabricating a sensor device on an ITO-coated glass substrate. The gas sensing characteristics of the prepared thin films were investigated for liquified petroleum gas (LPG), dimethyl propane, methane and butane test gases. The EG-doped PEDOT–PSS thin films exhibited excellent sensitivity for all the test gases, especially towards LPG, at room temperature. The sensitivity of the doped PEDOT–PSS films was recorded to be >90% for LPG with improved response and recovery time. The stability study indicated that the sensing response of doped PEDOT–PSS thin films was highly stable over a period of 30 days. Due to enhanced sensitivity, stability and fast response and recovery times, these EG-doped PEDOT–PSS thin films can be used in gas sensor technology, especially towards the detection of LPG at room temperature.