Gas-sensing properties on Cu-teteraazaannulene thin films

Abstract Interactions of NO 2 , NO, and O 2 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 NO 2 ≫NO>O 2 . When the film exposed to the gases at room temperature was heated up in N 2 atmosphere, the conductance went through a maximum at 85°C (NO 2 ), 100°C (NO), or 110°C (O 2 ), 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 NO 2 , NO, O 2 and N 2 , respectively. The dependence of the conductance ( G ) on the NO 2 concentration ( c ) in N 2 could be formulated well by G ∝ c 0.49 . These results suggested the promise of the CuTAA film for detecting NO 2 in air.