Oxidizing gas sensing properties of mesogenic copper octakisalkylthiophthalocyanine chemoresistive sensors

In this study, the effect of oxidizing gases, such as oxygen (O-2), nitrogen dioxide (NO2), and ozone (O-3), on a liquid-crystalline copper octakisalkylthiophthalocyanine[(C6S)(8)PcCu] thin film was investigated in the temperature range of 25-150 degrees C. Starting from a chloroform solution of (C6S)(8)PcCu, a jet-spray technique in an inert ambient atmosphere was used to coat the thin film of the compound on to an Interdigital Transducer (IDT) with gold electrodes. The concentration ranges for NO2 and O-3 exposed to the (C6S)(8)PcCu thin film were 1-10 ppm and 50 ppb-50 ppm, respectively. The response time in NO2 measurements was observed to be approximately 1 min at room temperature. and it decreased to a few seconds with increasing temperature. A good sensor response of 2000% ppm(-1) was observed when the sensor was exposed to 1 ppm NO2 at room temperature. The oxidizing gases were found to be desorbed by annealing the thin film. (C) 2009 Elsevier B.V. All rights reserved.