Nanostructured TiO₂ diffraction grating fabricated via imprinting and TiCl₄ treatment

We show here that a highly effective diffraction grating can be embedded into a nanoparticulate TiO₂ film via imprinting combined with TiCl₄ treatment. A thin TiO₂ film spin-coated on a glass substrate was patterned by imprinting and this patterned layer was TiCl ₄-treated with a higher concentration than for a thicker over-coated TiO₂ film. Due to the refractive index difference between the two layers, the incident light could be strongly diffracted. Different types of gratings have been incorporated into the films. A line grating with a 2 μm period and 1.2 μm thickness generated diffracted beams up to 3rd-order, with total diffraction efficiencies over 90% at 633 nm. This method has potential applications in TiO₂-based photovoltaic and photocatalytic devices.