Gas-sensing properties on Cu-teteraazaannulene thin films

Interactions of NO2, NO, and O-2 with a Cu-tetraazannulene (CuTAA) thin fil m were studied. These gases were found to act as an electron acceptor to in crease the conductance of the film (p-type), the tendency being in the orde r NO2 >> NO > O-2. When the film exposed to the gases at room temperature w as heated up in N-2 atmosphere, the conductance went through a maximum at 8 5 degrees C (NO2), 100 degrees C (NO), or 110 degrees C (O-2), indicating t hat the gas adsorption becomes reversible above these temperatures. The tem perature dependence of the conductance gave the activation energies of 0.27 , 0.51, 0.57 and 0.58 eV under exposure to NO2, NO, O-2 and N-2, respective ly. The dependence of the conductance (G) on the NO2 concentration (c) in N -2 could be formulated well by G proportional to c(0.49). These results sug gested the promise of the CuTAA film for detecting NO2 in air. (C) 2000 Els evier Science S.A. All rights reserved.