Well-controlled crystal growth of zinc oxide films on plastics at room temperature using 2D nanosheet seed layer

ZnO crystal films having a nearly perfect (001) orientation were successfully grown at room temperature on plastic and glass substrates by modifying their surface with Cs₄W₁₁O₃₆ nanosheets through a solution-based process. To clarify the effect of the monolayer film of Cs₄W₁₁O₃₆ nanosheets, the films were characterized by X-ray diffraction (XRD), 2D X-ray diffraction (2D-XRD), and high-resolution transmission electron microscopy (HRTEM). The results showed that the introduction of a typical 2D crystal surface with 2D-hexagonal structure (a = 0.727 nm) of Cs₄W₁₁O ₃₆ nanosheet promotes high-quality crystal growth of (001) oriented ZnO film (a = 0.325 nm). Highly crystalline texture directly formed on top of the substrates has been, to the best of our knowledge, realized for the first time, and it dramatically improves the film property, especially at the small film thickness region of <50 nm. The resistivity of the ZnO films significantly decreased when the films were fabricated on glass or plastic substrates with the nanosheet seed layer.