Investigation into Designing, Fabricating, and Characterizing Electrochromic Thin Films in the Visible Range.*

Electrochromic thin films are optical coatings capable of reversibly modulating their transmittance, reflectance, and absorbance under an applied voltage, making them suitable for applications such as smart windows, electronic displays, and tunable optical filters. Transition metal oxides like WO₃ and NiO serve as primary electrochromic layers and are fabricated via RF magnetron sputtering, which produces uniform, dense, and chemically stable films with precisely controlled thicknesses. Multilayer thin f ilm stacks can be engineered to enhance optical performance by tailoring optical constants and exploiting interference effects. Characterization in the visible spectrum is performed using a Cary Spectrophotometer to determine optical constants and properties for low-absorbing dielectric films. For highly absorbing films, variable-angle reflectometry with a 661 nm laser is employed, and the optical constants are extracted using the matrix transfer method. By carefully controlling film thickness, complex refractive index, and multilayer design, high optical contrast, rapid switching, and long-term stability can be achieved, enabling optimized performance for diverse optical engineering applications.Electrochromic thin films are optical coatings capable of reversibly modulating their transmittance, reflectance, and absorbance under an applied voltage, making them suitable for applications such as smart windows, electronic displays, and tunable optical filters. Transition metal oxides like WO₃ and NiO serve as primary electrochromic layers and are fabricated via RF magnetron sputtering, which produces uniform, dense, and chemically stable films with precisely controlled thicknesses. Multilayer thin film stacks can be engineered to enhance optical performance by tailoring optical constants and exploiting interference effects. By carefully controlling film thickness, complex refractive index, and multilayer design, high optical contrast, rapid switching, and long-term stability can be achieved, enabling optimized performance for diverse optical engineering applications.