ELECTROCHROMIC NICKEL-OXIDE-BASED THIN FILMS OPTIMIZED FOR ARCHITECTURAL APPLICATIONS

摘要

Electrochromic “smart windows” are able to change their transmittance of light and solar energy by electrical charging/discharging, thereby being able to provide a comfortable indoor climate together with energy efficiency. Many architectural applications require that these windows are capable of attaining a large transmittance in their fully bleached state. Electrochromic multilayer coatings with nickel oxide and tungsten oxide films joined by a polymer electrolyte have several good properties, but their optical absorptance has remained undesirably high. This paper reports on electrochromism in films based on nickel oxide with a variety of additives. The films were prepared by reactive DC and RF magnetron co-sputtering. The bleached-state absorptance was significantly lowered when the additive was of a type known to form oxides with large optical band gaps. The charge capacity was not impaired by the doping and, furthermore, the addition to the nickel sputter target rendered it non-magnetic, or weakly magnetic, which is a significant asset with regard to practical thin film deposition.