Use of ZnO as antireflective, protective, antibacterial, and biocompatible multifunction nanolayer of thermochromic VO ₂ nanofilm for intelligent windows

A multifunctional VO ₂ /ZnO bilayer film is designed and deposited by magnetron sputtering apparatus. The integration of the antireflective, antioxidative and anti-corrosion functions, and antibacterial performance makes the heterostructure film a promising candidate in the energy-saving smart window. The ZnO thin film as the antireflection layer can markedly boost the solar regulation efficiency (ΔT _sol ) from 7.7% to 12.2% and possesses excellent luminous transmittance (T _lum-L = 50.3%) in the low-temperature semiconductor phase. The ZnO layer as the protection barrier can not only protect VO ₂ thin film from oxidation to much toxic V ₂ O ₅ , but also decrease the release of V ions. Besides, the synergistic effect of releasing killing by Zn ²⁺ ions and contact killing by ZnO NPs makes ZnO thin film an outstanding antibacterial coating. In terms of the biological safety, ZnO coating with appropriate film thickness can effectively attenuate the cytotoxicity of VO ₂ on human HIBEpiC cells. We hope this work can provide new insights for better designing of novel multifunctional VO ₂ -based intelligent energy-saving windows.