High-Performance NO2 Sensors Based on Ultrathin Heterogeneous Interface Layers

Gas sensors based on different interface layers are prepared by vacuum evaporation method. In comparison with the microscope images of films on different interface layer, zinc phthalocyanine (ZnPc) films exhibit good continuity on the heterogeneous interface of p-sexiphenyl/alpha-sexithiophene (p-6P/alpha-6T). Under the optimal conditions of ZnPc films, ZnPc film sensors with high performance are obtained based on ultrathin heterogenous interface layers. The responsivity is up to 2271% at 3 ppm NO2 gas and the sensitivity is 570% ppm(-1). The minimum detection limit of sensors is lower than 500 ppb and the responsivity is 157% to 500 ppb NO2 gas. The high performance of sensors is attributed to the ultrathin heterogeneous interface layer. The island-like p-6P domains at the bottom provide the precursor for the growth of alpha-6T layer while the alpha-6T molecules fill the interval of p-6P islands, as a result, a continuous interface for the growth of ZnPc molecules came into being. In addition, the ZnPc and alpha-6T films have high electrical characteristics. The results are favorable for the adsorption and desorption of NO2 gas molecules. The ultrathin heterogeneous interface layer provides a feasible research evidence for the further research and development of ultrathin and flexible electronic devices.