Bilayer polymer dielectric systems for high response NO2 gas sensors

Abstract

In this study, the effects of bilayer polymer dielectric systems on the characteristic of nitrogen dioxide (NO2) gas sensors and organic field effect transistor (OFET) were investigated. Different bilayer polymer dielectrics were obtained by depositing polymethyl methacrylate (PMMA) films on monolayer polystyrene (PS), polyvinyl pyrrolidone (PVP), or PMMA films by spin coating. The responsivity of PS/PMMA-based sensors to 30 ppm NO2 gas is up to 7633%, which is 35.7% higher than that of PMMA/PMMA-based sensors. Meanwhile, the sensitivity to NO2 gas has increased from the lowest 191%/ppm to 265%/ppm. The copper phthalocyanine (CuPc) film on PS/PMMA dielectric layer is induced to form more gaps between the rod domains, which are favorable to the gas interaction. The response mechanism was proposed that the equivalent three-dimensional sensing films caused by multi-layer polymer dielectrics play a significant role in the remarkable increase of gas response.