Reversible wettability control of ZnO thin films synthesized by hydrothermal process on different buffer layers

•ZnO films were prepared by hydrothermal process on both AZO and ITO buffer layers.•The ZnO film on AZO showed an imperceptible light-induced wettability response.•The ZnO film on AZO showed a reversible thermal-incuced wettability transition.•Both light- and thermal-induced wettability transitions of the ZnO/ITO were achieved.•This work may provide a basis for wettability control in ZnO-based applications.

The wetting behaviors of zinc oxide (ZnO) thin films, which were grown on aluminum-doped zinc oxide (AZO) and tin-doped indium oxide (ITO) buffer layers by hydrothermal process, are reported. The ZnO film grown on the AZO layer, which has a morphology containing micro- and nanoscaled features, shows a slight decrease in water contact angle (WCA) after UV illumination. The ZnO film grown on the ITO layer, which is composed of single-scale microrods, exhibits a transition between hydrophobicity and superhydrophilicity under UV exposure for 8 h and dark storage for 2 weeks. The wettabilities of the both films are enabled to convert reversibly by alternative heating at 400 °C and 100 °C. This work may be of huge importance from the viewpoint of self-cleaning and anti-fogging applications based on wettability control of ZnO films.

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