Poly[2,5-bis(3-tetradecylthiophen-2-yl) thieno [3,2-b] thiophene] Organic Polymer Based-Interdigitated Channel Enabled Thin Film Transistor for Detection of Selective Low ppm Ammonia Sensing at 25°C

Abstract

In the present work, we have developed a solution-processable poly (2,5-bis (3-tetradecylthiophen 2yl) thieno(3,2b) thiophene) (PBTTT-C14) based organic thin film transistor, for possible selective sensing the toxic ammonia (NH3) gas at 25°C. This thin-film transistor based sensor makes use of PBTTT-C14 polymer as an organic channel that exhibits highly responsive (>61%) behavior at different levels of ammonia concentrations, even in presence of a mixture of ethanol and butanol gases in a humid environment. The notable changes are observed in the transistor parameters including channel mobility, threshold voltage and the on-off ratio. Interdigitated channels obtained using shadow masking technique enables the device to respond to a low ammonia concentration (<10 ppm). Better sensing capabilities with a detection limit of 2 ppm, the response time of 30 sec and recovery time of 40 sec of exposed ammonia, butanol and ethanol gases have been recorded. The mechanism of sensing has been explained for a better understanding of electrostatic and chemical interaction between gases and PBTTT-C14 semiconductor. Electrical characterizations of the device for the sensing were carried-out in the ambient condition. The device performance has been tested in humid environmental conditions. The fabricated device exhibited enormous potential for ammonia sensing for real-life applications.