Numerical and Experimental Investigation of Infrared Optical Filter Based on Metal Oxide Thin Films for Temperature Mitigation in Photovoltaics

Various metal oxide thin films, including TiO₂, SnO₂, MoO₃, and NiO, grown by the electron-beam evaporation process, have been optimized for implementation as multilayered structures for infrared (IR) filter-based photonic cooler application. The filter and antireflection coating designs were based on various stacking configurations with titanium dioxide (TiO₂) and tin dioxide (SnO₂) used as seed layers. These designs were then optimized to achieve wideband optical transmission in the visible spectrum but cut off the infrared region. After deposition, the dual-layer filter configurations were characterized optically and structurally using ultraviolet–visible (UV–Vis) spectrometry, ellipsometry, three-dimensional (3D) profilometry, x-ray diffraction analysis, and scanning electron microscopy. A systematic comparison between these filters confirmed that stacking layers with TiO₂ are the best candidate for photovoltaic modules as they demonstrate higher transmission and a clear cutoff after 1000 nm. Finally, computational analysis using OptiLayer software demonstrated a minimum optical reflectance of about 0.4% when coupling an oxide layer with a lower refractive index value (e.g., 1.4) with one having a higher refractive index (> 2). These results illustrate the promising potential of such films for IR filter-based photonic cooling of photovoltaics and/or smart windows. Graphical abstract: [Figure not available: see fulltext.]