Thin film multilayers on a glass substrate attract great attention as heat mirrors for economical and ecological house windows. The required optical properties of the heat mirror are a high transmittance in visible light combined with a high reflectance in infrared and ultraviolet ranges. These requirements can be realized using a thin film of noble metal (Au, Ag) or metal-like nitrides (TiN, ZrN) sandwiched between two layers of antireflection coatings made from the transition metal oxide. In particular, TiO2/TiN/TiO2 stacked film on a glass promises perspective applications due to high stability of the optical properties and potentially easy manufacturing process.
In this study, we prepared TiO2/TiN/TiO2 heat mirrors on glass substrates using a TiN single target pulsed laser deposition technique. Transition in TiO2-to-TiN layers composition was achieved by changing atmosphere gas (oxygen-to-nitrogen). Film processing parameters (gas pressure and substrate temperature) have been optimized controlling films crystalline structure by X-ray diffraction and optical spectra in the range 400 to 2400 nm. Finally, achieved 90% transmittance in visible and about 15% in IR demonstrate feasibility to use TiO2/TiN/TiO2 as an effective heat mirror. Furthermore, multifunctional properties can be expected through precise control of the crystalline structure of the TiO2 top layer to operate as a photocatalyst.
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