Self‐Cleaning Titanium Dioxide Metasurfaces with UV Irradiation

Abstract The delicate nature of optical components requires very special handling and storage procedures to maximize their performance and lifetime. In the optical field, a long‐standing challenge is the cleaning of unavoidable contaminants during the daily use, especially for the coated elements and the biomedical diagnostic devices. Herein, the authors tackle this problem and experimentally demonstrate TiO 2 based self‐cleaning optical meta‐devices with the illuminating of UV light. By arranging TiO 2 nanopillars into different patterns, high‐efficiency TiO 2 meta‐devices have been realized for the visible spectrum, for example, color nano‐printings, metalenses, and meta‐holograms. The TiO 2 meta‐devices become hydrophilic and photoactive under UV irradiation. Consequently, the contaminants, such as, stearic acid or fingerprints have been completely cleaned. Owing to the stability of TiO 2 , the self‐cleaning effect and the internal nanostructures of meta‐devices are well preserved for many rounds of contamination. This research shall bring new opportunities to TiO 2 metasurfaces for extreme applications.