Flexible NO gas sensor based on conducting polymer poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT)

Abstract

Flexible gas sensor for Nitric Oxide (NO) detection has been realized using conducting polymer poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) as the gas sensing material. This has been achieved by the deposition of PCDTBT on flexible BOPET substrate using the simple technique of spin coating. PCDTBT has been found to be highly selective for NO gas with a very good response for upto 5ppm level of NO gas (toxic limit - 25ppm). The XPS study on PCDTBT films has revealed no change in the chemical composition of deposited PCDTBT polymer, thus, showing no degradation of deposited film by the oxygen or moisture present in the ambient atmosphere during the gas sensing measurements. The gas sensing measurements were done for 35days to determine the reproducibility of sensor. The measurements confirmed the long term environmental stability of PCDTBT showing it to be a reliable and effective material for NO gas sensor. In addition, the gas sensing measurements of PCDTBT under bending conditions with improved performance were also carried out, showing its application as a novel gas sensing material for the flexible NO gas sensor. The possible gas sensing mechanism of PCDTBT, a p-type material, was also investigated using work function and impedance spectroscopy measurements.