GAS-SENSING PROPERTIES OF METALLO-PHTHALOCYANINE THIN-FILMS AS A FUNCTION OF THEIR CRYSTALLINE-STRUCTURE

PcM (M = Cu, Fe, Pb, Li) thin films are studied as sensitive elements of semiconducting gas sensors. After exposure to oxidizing gases (NO2, O2, Cl2, I2), the electrical conductivities of the materials go through a maximum at temperature T(m), which corresponds to the maximum sensitivity to the gas and thus to the temperature of operation as gas sensors. We describe the evolution of T(m) with the morphology of the film and with the heat and gaseous treatments, and its consequences with regard to the gas-sensing application.