uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
On the chromogenic behavior of tungsten oxide films: A cryogenic experiment
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
2015 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The chromogenic properties of tungsten trioxide (WO3) have been studied by photoluminescence spectroscopy at 4.2 K in order to characterize the electronic structure of this material and see how this relates to optical responses during chromogenic coloration. Transition processes between electron energy states are often the cause of optical phenomena and it is important to identify such processes in order to understand the chromogenic coloration of tungsten oxide films. Much research work has been devoted to characterize the physical and chemical mechanisms that are responsible for this coloration and this is of fundamental

importance to understand the chromogenic behavior. The latest research shows that oxygen vacancies could play an important role in certain coloration processes, but it is still a matter of debate whether these are important for the overall response. This work aims to identify specific transitions that are related to oxygen vacancies by measuring photoluminescence from films with controlled vacancy content. The main goal of the project was to set up an experiment that could measure photoluminescence at liquid helium temperature. This was done by installing and integrating the components included in this experimental set-up. The films had been prepared prior to this work and were deposited on a nanocrystalline CaF2 substrate, which is a material that has a very large band gap and was therefore expected to fully transparent in the UV range. However it was found that the substrate inelastically scattered the UV excitation light, which produced strong signals that overshadowed the photoluminescence and prevented an effective characterization of the electronic structure in the films. Instead, suggestions were given on how to minimize uncertainty factors and overcome the difficulties met in this work. It was also found that the films attain a lasting blue coloration by exposure to UV light in vacuum, and that this might be due to oxygen being desorbed from the film during experiments in vacuum. 

Place, publisher, year, edition, pages
2015. , 60 p.
UPTEC K, ISSN 1650-8297 ; 15032
Keyword [en]
Photoluminescence, chromogenic, band gap, electronic orbital, density functional theory, optical interference
National Category
Natural Sciences Engineering and Technology
URN: urn:nbn:se:uu:diva-263554OAI: oai:DiVA.org:uu-263554DiVA: diva2:858646
Educational program
Master Programme in Chemical Engineering
2015-09-04, Å12167, Ulleråker, 752 37, Uppsala, 15:36 (English)
Available from: 2015-11-06 Created: 2015-10-02 Last updated: 2015-11-06Bibliographically approved

Open Access in DiVA

fulltext(3359 kB)99 downloads
File information
File name FULLTEXT02.pdfFile size 3359 kBChecksum SHA-512
Type fulltextMimetype application/pdf

By organisation
Department of Chemistry - Ångström
Natural SciencesEngineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 99 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 271 hits
ReferencesLink to record
Permanent link

Direct link