Phthalocyanine semiconductor sensors for room-temperature ppb level detection of toxic gases

Abstract

Nickel and lead phthalocyanine (NiPc and PbPc) thin films prepared by vacuum sublimation have been investigated for use as gas sensors. High sensitivity (25 ppb), reversibility, and very fast response time (∼ seconds) have been demonstrated for detection of NO2 at room temperature. The sensor output increases by five to seven orders of magnitude as the gas concentration is increased from ∼2×101 to 6×104 ppb. Measurements of transient response characteristics versus gas concentration exhibited a simple logarithmic dependence. Application of this approach to the detection of other agents is discussed. It appears that the unique electrical properties of these films are a result of the film morphology associated with our specific deposition approach. Detection based on optical sensing of NO2 has also been demonstrated.