Tailoring the performance of phthalocyanine-based sensor: Side chain substitution and nanofabrication

Abstract

Room temperature Cl2 sensing properties of chemiresistive gas sensor based on Zinc Phthalocyanine (ZnPc) were improved by functionalizing ZnPc molecule with peripheral substitution of alkoxy side chains. The chemiresistive sensors of substituted ZnPc (ZnPcOC8) were made using spin-coated films and solution-processed nanostructures. These sensors were highly selective and sensitive towards Cl2 as compared to NH3, NO and NO2. The chlorine response kinetics of ZnPc and substituted ZnPcOC8-based sensors were investigated for Cl2 concentration range 5–1500 ppb. The ZnPcOC8-based sensors exhibit a limit of 5 ppb Cl2 with faster sensing kinetics as compared to ZnPc-based sensor. Among the three sensors, the solution-processed nanostructured-based sensor exhibits the best performance. The gas sensing mechanism of sensors has been investigated by XPS, suggesting that Zn+2 were the preferred sites for Cl2 interaction. These investigations suggest that alkoxy substitution on phthalocyanine molecules leads to development of cost effective and highly sensitive chlorine gas sensors.