Gas-sensing properties on Cu-teteraazaannulene thin films

Interactions of NO2, NO, and O2 with a Cu-tetraazannulene (CuTAA) thin film were studied. These gases were found to act as an electron acceptor to increase the conductance of the film (p-type), the tendency being in the order NO2≫NO>O2. When the film exposed to the gases at room temperature was heated up in N2 atmosphere, the conductance went through a maximum at 85°C (NO2), 100°C (NO), or 110°C (O2), indicating that the gas adsorption becomes reversible above these temperatures. The temperature dependence of the conductance gave the activation energies of 0.27, 0.51, 0.57 and 0.58 eV under exposure to NO2, NO, O2 and N2, respectively. The dependence of the conductance (G) on the NO2 concentration (c) in N2 could be formulated well by G∝c0.49. These results suggested the promise of the CuTAA film for detecting NO2 in air.