The influence of polymer dielectrics on electrical and sensory properties of organic field-effect transistors

The work describes one of the stages of development of flexible polymer gas sensors based on organic field-effect transistors (OFETs) and is devoted to revealing the dependencies of the electrical and sensory properties of these devices on the characteristics of the polymer dielectric layer of the OFETs. The influence of the material of the dielectric layer, as well as the conditions of its application to the polymer substrate were investigated. It was shown that the surface morphology and the properties of the semiconductor layer, which was formed on top of the polymer dielectric by thermal evaporation in vacuo, strongly depend on the value of the surface energy of the dielectric used, while the roughness of its layer has no considerable effect on the morphology. The highest electrical characteristics were demonstrated by the OFETs based on the dielectric with the highest value of surface energy, that is, polymethyl methacrylate. At the same time, regardless of the dielectric used, all the sensor devices demonstrate a high sensitivity towards nitrogen dioxide, which has values that are comparable to those characterizing the sensitivity of similar devices fabricated on silicon substrates using the studied dielectrics as interface layers, as well as an ability towards recovery of the starting properties in pure air that is higher compared to that of silicon samples, which is very promising for the commercial application of the developed polymer gas sensors.