Fabrication of TiO₂ Micropatterns on Flexible Substrates by Vacuum‐Ultraviolet Photochemical Treatments

Abstract

Titanium dioxide (TiO₂) micropatterns have received great attention for application in photocatalysis, electronics, and optoelectronics. Formation of such micropatterns on polymer substrates is of importance in flexible device fabrication. Vacuum ultraviolet (VUV) oxidative treatment applied on metalorganic precursor gel films serves as a strategy to fabricate metal oxide films on heat‐sensitive substrates such as polymers. Here, 172 nm VUV oxidative treatment through a photomask is used to directly convert the titanium metalorganic precursor films into TiO₂ patterns without further heat annealing. In comparison to the commonly used alkoxide‐based precursors, titanium acetylacetonate proves to be an appropriate precursor due to its chemical stability in an ambient environment. With this precursor, clear removal of untreated precursor gels is achieved, resulting in well‐defined amorphous TiO₂ micropatterns with a minimum feature of 1 µm and a small edge roughness less than ≈4%. The innovativeness arises from the one‐step VUV photochemical conversion in the whole ambient conditions, which largely reduces complex processes, for example, nitrogen‐filled glovebox or post‐heat treatments. High‐quality amorphous TiO₂ micropatterns can be applied to device fabrication of solar cells and memories. This patterning approach highlighting TiO₂ can be also extended to other metal oxides, which has great potential in surface and device processing.