Structural, optical and electrochromic properties of WAW films for profound electrochromic applications deposited by DC & RF magnetron sputtering

Abstract

One of the most frequently used transition conducting oxides (TCO) is indium tin oxide. Indium is very expensive because of the lack of availability. So Most of the researchers focused on cost-effective materials and they have developed Dielectric/Metal/Dielectric (DMD) structures for ITO-free applications. Examples of dielectric materials are AZO, MoO3, TiO2, and WO3. The dielectric material is sandwiched between metals such as Au, Ag, Pt, Cu, and Al. The efficacy of these DMD structures is purely based on the thickness of the dielectric and metal layers. Once the metal layer thickness is more than 15 nm, the transmittance is much less due to the thickness of the material and it will work as a reflector. Moreover, as WO3 is the most widely and frequently used material we focus on the fabrication of WO3/Ag/WO3 (WAW) for replacing TCO in the electrochromic device and making it indium-free. WAW structures are widely used in smart windows, gas sensors, solar cells, photodetectors, etc. For electrochromic applications, these WAW structures showed good transmittance, fast switching speed, best coloration efficiency, and best optical modulation in comparison to WO3/ITO structure and are also cost-effective.