Room temperature nitrogen dioxide chemresistor using ultrathin vanadyl-phthalocyanine film as active layer

A room temperature nitrogen dioxide (NO2) chemresistor using 1.8 nm ultrathin vanadyl-phthalocyanine (VOPc) film as active layer has been prepared by Weak Epitaxy Growth (WEG) method. Its gas sensing properties to NO2 have been compared with a 7 nm polycrystalline VOPc chemresistor. The ultrathin film device shows stronger response and better recovery character. Further results reveal that the two-dimensional transport film provides an effective charge transfer system after NO2 adsorption and it gets rid of bulk diffusion at the same time. Kelvin probe force microscopy (KPFM) results suggest that grain boundaries are easily doped by analyte but is slow in desorption compared with crystal grains. The ultrathin film device shows advanced sensing mechanism compared with the polycrystalline film.