Near infrared and visible optical properties in electrochromic crystalline tungsten oxide thin films on ITO
Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
In this project I have studied the optical properties of electrochromic crystalline tungsten oxide, WO3. The practical application could be for a window for desalination of sea water which requires a high absorption coefficient A(λ) for near infrared radiation (NIR), while at the same time a high transmittance T(λ) in the visible spectral range.
An electrochromic (EC) material is a material that changes its optical properties when inserting or extracting ions by applying a voltage. The WO3 was prepared on a glass substrate coated by a transparent electrical conductor. The conductor used is tin doped indium oxide. In2O3:Sn, indium-tin-oxide (ITO). The preparation of the thin films has been carried out using DC magnetron reactive sputtering. The structure of unheated tungsten oxide is amorphous and once heated it is crystalline. Li+ ions were inserted into the tungsten oxide material with electrochemical methods to create the coloring effect. The optical properties were recorded in the 330 < λ < 2500 nm wavelength range by use of a Perkin-Elmer Lambda 9 spectrophotometer.
The highest reflectance R(λ), approximately 50% in NIR and absorption coefficient
A(λ) = 1,5 x 105 [cm-1], were measured for the sample that had been post annealed at 500 deg C. The crystalline tungsten oxide films provides for a good switching capability in the NIR spectral range wile at the same time maintaining a high transmittance T(λ) in the visible spectrum.
Place, publisher, year, edition, pages
2010. , 48 p.
Other Physics Topics
IdentifiersURN: urn:nbn:se:uu:diva-229122OAI: oai:DiVA.org:uu-229122DiVA: diva2:735742
Master Programme in Physics
2010-09-21, Division of Solid State Physics Department of Engineering Sciences, The Ångström laboratory Uppsala University, SE-751 21 Uppsala, Sweden, 10:00 (English)
Niklasson, Gunnar, Professor
Rubensson, Jan-Erik, Professor