High-sensitivity chlorine gas sensors using metal-phthalocyanine thin films

Abstract

Chlorine (C12) gas sensors were newly developed using metal-phthalocyanines (MPc) such as CuPc, MgPc, ZnPc and FePc. All gas sensors using MPc thin films deposited by a vacuum evaporation method exhibited an increase in conductance with exposure to C12 gas at an operating temperature in the rage from 25 to approximately 200°C. The obtainable sensitivity of sensors was considerably affected by the MPc material used and the deposition conditions. The transient response of sensitivity was strongly dependent on the operating temperature of the MPc thin-film sensors. The increase in conductivity of the MPc thin films used in sensors that results from an increase in C12 gas concentration can be explained by the increase of carrier concentration dominating the effect of a decrease in Hall mobility. A high sensitivity as well as a fast response were realized for CuPc and MgPc thin-film sensors operated at approximately 200°C; C12 gas at a concentration of 0.18 ppm could be detected using these thin-film sensors operated in the range from 25 to 200°C.