Polymer/Graphene oxide nanocomposite thin film for NO2 sensor: An in situ investigation of electronic, morphological, structural, and spectroscopic properties

The higher operating temperature of metal oxide and air instability of organic based NO₂ sensor causes extremely urgent for development of a reliable low cost sensor to detect NO₂ at room temperature. Therefore, we present a fabrication of large area Polymer/GO nano hybrid thin film for polymer thin film transistors (PTFTs) based NO₂ sensors assisted via facile method named 'spreading-solidifying (SS) method', grown over air/liquid interface and successive investigation of effect of NO₂ on film via several characterizations. The PTFTs sensor has demonstrated swift and high response towards low concentration of NO₂ gas with air stability and provided real time non-invasive type NO₂ sensor. Herein, we are reporting the nanohybrid PBTTT/GO composite based PTFT sensor with good repeatability and sensor response for low concentration NO₂. The thin film grown via SS technique has reported very good adsorption/desorption of target analyte having response/recovery time of 75 s/523 s for 10 ppm concentration of NO₂ gas. It has been observed that % change in drain current (sensor response) saturated with increasing concentration of NO₂. The transient analysis demonstrates the fast sensor response and recovery time. Furthermore, in order to understand the insight of high performance of sensor, effect of NO₂ on nanohybrid film and sensing mechanism, an in situ investigations was conducted via multiple technique viz. spectral, electronic, structural, and morphological characterization. Finally, the performance of sensor and the site of adsorption of NO₂ at polymer chains were argued using schematic diagram. This work shows the simple fabrication process for mass production, low cost and room temperature operated gas sensors for monitoring the real-time environment conditions and gives an insight about the sensing mechanism adsorption site of NO₂.