Enhanced formaldehyde photoelectric response on ZnO film illuminated with visible light

Photoelectric responses of ZnO to dry air and formaldehyde under visible light illumination were studied in this work. ZnO film was prepared on Al2O3 substrate by screen printing. Fundamental characteristics of ZnO film were examined through XRD, FE-SEM and PL spectra measurements. Time-dependent photocurrent properties of ZnO were tested in dry air and formaldehyde under the illumination of white light, respectively. The results revealed that, in comparison with dry air, ZnO in formaldehyde exhibited an enhanced photocurrent response. To illustrate it, explanations based on the double Schottky barrier model were proposed. In addition, to demonstrate the authenticity of the proposed mechanism, experiments on the time-dependent photocurrent of ZnO under white light illumination in the light-on and light-off conditions were also carried out. (C) 2016 Elsevier B.V. All rights reserved.