Polymer dielectric layer functionality in organic field-effect transistor based ammonia gas sensor

Abstract

Ammonia (NH3) gas sensors based on pentacene organic field-effect transistors (OFETs) are fabricated using polymers as the dielectric. Compared with those incorporating poly(vinyl alcohol), poly(4-vinylphenol) or poly(methyl methacrylate) dielectric, a low detect limitation of 1ppm and enhanced recovery property are obtained for OFETs with polystyrene (PS) as gate dielectric. By analyzing the morphologies of pentacene and electrical characteristics of the OFETs under various concentrations of NH3, the variations of the sensing properties of different dielectrics based OFET-sensors are proved to be mainly caused by the diversities of dielectric/pentacene interfacial properties. Furthermore, low surface trap density and the absence of polar groups in PS dielectric are ascribed to be responsible for the high performance of NH3 sensors.