Gas sensitive light emission properties of tin oxide and zinc oxide nanobelts

Light emission properties of tin oxide and zinc oxide nanobelts and nanowires have been investigated by means of continuous wave and time resolved photoluminescence. In both kind of nanostructures, photoluminescence quenching was observed at increasing temperature and at interaction with 5 ppm concentration NO2. Photoluminescence time decay measurements in the visible range suggest that adsorbed NO2 induces fast non-radiative relaxation of surface electrons, competing with radiative surface-localized recombination. Such fast interaction between electrons and molecular adlayer may reduce the number of possible radiative recombination events at surface without significantly changing the subsequent slower radiative processes. Our measurements also show that adsorbate-related non-radiative recombination time should be lower than 1 ns.