Effects of sensing temperature on the NO2-sensing properties of octa-iso-pentyloxymetallonaphthalocyanine spin-coated films

A kind of 1,6,10,15,19,24,28,33-octa-iso-pentyloxy-2,3-metallonaphthalocyanines complexes MNc(iso-PeO)8 (M = Co, Cu, Pd) are used as spin-coating film-forming materials. The surface morphologies of the films prepared were studied first. These films were then used for the experiments of NO2 sensing. The effects of sensing temperature as well as the NO2 concentration on the sensing properties were studied. The experimental results showed that the three MNc(iso-PeO)8 films were uniform, smooth and dense. Due to the different metal ions (M) on the center of naphthalocyanine, the CoNc(iso-PeO)8 film had a higher film resistance and response-recovery rate in the NO2 sensing experiments. On the contrary, the response to NO2 of the PdNc(iso-PeO)8 and CuNc(iso-PeO)8 films were superior to that of CoNc(iso-PeO)8. By varying the sensing temperature, it was found that the elevation of sensing temperature could improve the sensing response, recovery ratio, and sensitivity of the sensing films. At high concentrations of NO2, the response time became shorter.