Conjugated polymer–zeolite hybrids for robust gas sensors: Effect of zeolite surface area on NO2 sensing ability

Abstract

• Conjugated polymer–zeolite hybrids effectively adsorbs gas molecules, which improves its NO 2 sensing performance. • The NO 2 adsorbed by zeolite can exert a p-type doping as an electron acceptor, thereby inducing an increase in the on-current. • The PST-11:P3HT film exhibited the higher NO 2 responsivity and sensitivity because of its greater surface area. • The zeolites embedded in the P3HT effectively protected the polymer from oxidation by water or oxygen. The organic field-effect transistor-based gas sensors are promising next-generation gas sensors with reliably high sensitivity and broad potential for various applications, such as E-skin and portable gas sensors, because they are lightweight, mechanically flexible, and cost-effective. However, despite the high gas responsivity of organic gas sensors, they still face challenges from the device instability under ambient conditions, which lags far behind inorganic-based gas sensors. We here report the fabrication of a novel organic–inorganic hybrid gas sensor based on the hybridization of zeolite and a conjugated polymer. We incorporate zeolite materials, PST-11 and Omega, in a conjugated polymer, P3HT, matrix, which significantly improves its NO 2 sensing performance in conjunction with high responsivity and high recovery rates due to the high surface-to-volume ratio and orderly structure of two zeolites. Comparing those two zeolites, the PST-11:P3HT film, in particular, exhibited higher NO 2 responsivity and sensitivity because of its larger specific surface area than Omega. We also demonstrate that the zeolite materials embedded in the semiconductor polymer can protect the blend film from oxidation during long-term storage under ambient conditions by the zeolite’s ability to adsorb oxidizing molecules, which leads to good long-term stability of composite transistor devices under ambient atmosphere. This study demonstrates that zeolite-based materials have potential applications in organic gas sensors.