The gas sensitivity of Langmuir-Blodgett films of a new asymmetrically substituted phthalocyanine

Langmuir-Blodgett (LB) films of amino-tri-tert-butyl-phthalocyanine (AmBuPc) were fabricated. The gas sensitivities of the low-conducting LB films were measured in different concentrations of NO2 atmosphere. The results showed that a good linear relationship exists between the logarithm of the resistance of AmBuPc gas sensor and the concentration of NO2, which could be explained in terms of the gas diffusion theory in the LB films. XPS results proved that the attack centers of NO2 are the two pyrrole N-linked free H atoms of the Pc macro-ring. Temperature had significant influences to the recovery and cyclic properties of sensor and the conductivity of gas sensor. The values of activation energy are 0.14 and 0.43 eV, respectively, at temperatures lower and higher than 60 degrees C in NO2. (C) 1999 Elsevier Science S.A. All rights reserved.