Combined electrochromic-transparent conducting coatings consisting of noble metal, dielectric and WO3 multilayers
| Autor: | George Leftheriotis, P. Yianoulis, E. Koubli |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment business.industry chemistry.chemical_element Dielectric engineering.material Tungsten Electrochromic devices Surfaces Coatings and Films Electronic Optical and Magnetic Materials Optics Coating chemistry Electrochromism engineering Transmittance Optoelectronics business Layer (electronics) Transparent conducting film |
| Zdroj: | Solar Energy Materials and Solar Cells. 116:110-119 |
| ISSN: | 0927-0248 |
| DOI: | 10.1016/j.solmat.2013.04.013 |
| Popis: | A computer code based on the characteristic matrix formulation and a Monte Carlo algorithm have been devised for the optical design of D/M/WO 3 combined electrochromic-transparent conducting coatings. When these coatings are incorporated into electrochromic devices, the WO 3 film serves a dual purpose: It anti-reflects the metal in the bleached state and becomes absorptive in the colored state (as a Li x WO 3 tungsten bronze). The optimum design was found to be Glass/ZnS (34 nm)/Ag (15 nm)/WO 3 (326 nm), with the WO 3 layer being thick to ensure adequate optical modulation. Simulation of the coating in the colored state revealed an asymmetry in its response related to the direction of the incoming radiation, with high absorptance in one direction and high reflectance in the opposite one. This feature was verified experimentally and it has not been observed in typical electrochromic devices. Substitution of the ZnS layer with WO 3 , of the Ag layer with Au, and addition of a 4th Al 2 O 3 protective layer were found to be feasible alternatives to the optimum design. Glass/WO 3 /Ag/WO 3 coatings have been fabricated by electron beam gun deposition. They are transparent in the visible ( T lum =57%), reflective in the infrared with emittance equal to 0.09 and electrically conductive ( R sheet =9 Ω). These coatings were incorporated into electrochromic devices of the type Glass/WO 3 /Ag/WO 3 /1 M LiCLO 4 –PC/SnO 2 :F/Glass. Such devices exhibit a transmittance contrast ratio of 10:1 at 550 nm for 90 mC/cm 2 of inserted charge density, and a coloration efficiency of about 30 cm 2 /C at 534 nm. They can also withstand more than 500 voltammetric coloration–bleaching cycles. |
| Databáze: | OpenAIRE |
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