Room temperature NO2 sensing properties of polythiophene films

• PTh thin film sensor work at room temperature.
• PTh films exhibit highly selective/sensitive detection of NO2 at ppm level.
• PTh sensor is 99% reproducible and 52% stable.
• PTh sensor detect NO2 at 10 ppm (9%).

Chemical oxidation polymerization technique was employed for the formation of polythiophene. Gas sensors based on polythiophene were prepared on glass substrates using spin coating technique. Structure and morphology of polythiophene have been characterized using FTIR and FESEM techniques. The surface topography and roughness of the surface have been investigated using AFM technique. Room temperature gas sensing performance of the polythiophene films have been studied for various reducing (H2S, NH3, CH3OH and C2H5OH) as well as oxidizing (NO2 and Cl2) gases. We demonstrate that, the polythiophene films are highly selective towards NO2 gas at room temperature with high sensitivity, good selectivity and excellent repeatability. The sensor response was estimated by the change in the electrical resistance of the film in the presence and absence of NO2 gas. Furthermore, the polythiophene sensor is able to detect up to 10 ppm of NO2 gas with reasonable sensitivity and it can be reliably used to monitor the concentration of NO2 over the range 10–100 ppm. Plausible sensing mechanism of polythiophene sensor towards NO2 gas is also discussed. Our reproducible experimental results clearly demonstrate that, polythiophene sensor have a great potential for NO2 sensing applications at room temperature operations.

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