ZnO-ZrO₂ films with good UV-shielding properties prepared by a single step sol-gel method

Abstract

This paper describes a single step sol-gel method, which is very useful for the manufacturing of various films. In this paper, ZnO-ZrO₂ films with excellent ultraviolet ray shielding property were fabricated by a single step deposition of sol-gel spin coating. Zinc acetate dihydrate [Zn(OCOCH₃)₂·2H₂O] and zirconium n-propoxide [Zr(OC₃H₇)₄] were used as starting materials. Monoethanolamine was added to dissolve zinc acetate in alcoholic solvent. Precursor solution with the molar ratio of [Zn]/[Zr] from 100/0 to 60/40 were prepared for the deposition. The effects of zirconium addition on the stability of the precursor solution, crystallization behavior of ZnO-ZrO₂ film, optical property and microstructure were examined. As a result, the stability of the precursor solution increased with increasing ZrO₂ content. Dried films with zirconia component were more stable to humidity in air than the films without zirconia. The addition of zirconia component to the ZnO film also improved the microstructure of the film surface. Namely, the surface of the film with the molar ratio [Zn]/[Zr] of 70/30 became flat without crack. Relatively thick ZnO-ZrO₂ film with thickness about 0.7 μm was obtained by the single step deposition. The resultant film with a [Zn]/[Zr] of 70/30 exhibited high transmittance in the visible region (T_VIS∼90%) and low transmittance in the ultraviolet region (T_UV < 10%). This suggested that the ZnO-ZrO₂ film with good UV-shielding property was successfully prepared by a single step sol-gel spin coating.