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

Abstract

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.] 2021, The Minerals, Metals & Materials Society.