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 wer e measured in different concentrations of NO2 atmosphere. The results showe d that a good linear relationship exists between the logarithm of the resis tance of AmBuPc gas sensor and the concentration of NO2, which could be exp lained in terms of the gas diffusion theory in the LB films. XPS results pr oved that the attack centers of NO2 are the two pyrrole N-linked free H ato ms of the Pc macro-ring. Temperature had significant influences to the reco very and cyclic properties of sensor and the conductivity of gas sensor. Th e values of activation energy are 0.14 and 0.43 eV, respectively, at temper atures lower and higher than 60 degrees C in NO2. (C) 1999 Elsevier Science S.A. All rights reserved.