Transparent conductors as solar energy materials: A panoramic review

Electrochromic tungsten oxide films: Review of progress 1993–1998

Mesoporous semiconducting films consisting of preferentially orientated monoclinic-phase nanocrystals of tungsten trioxide have been prepared using a novel version of the sol−gel method. Transformations undergone by a colloidal solution of tungstic acid, stabilized by an organic additive such as poly(ethylene glycol) (PEG) 300, as a function of the annealing temperature have been followed by means of a confocal Raman microscope. The shape and size of WO3 nanoparticles, the porosity, and the properties of the films depend critically on preparation parameters, such as the tungstic acid/PEG ratio, the PEG chain length, and the annealing conditions. Well-crystallized WO3 films combine excellent photoresponse to the blue region of the solar spectrum, up to 500 nm, with good transparency at wavelengths larger than 550 nm. Particular applications of these nanocrystalline WO3 films include photoelectrochemical and electrochromic devices.

Crystallographically oriented mesoporous WO3 films: synthesis, characterization, and applications.

Electrochromics for smart windows: Oxide-based thin films and devices

UV−visible diffuse reflectance spectroscopy was used to probe the electronic structure and domain size of tungsten oxide species in crystalline isopolytungstates, monoclinic WO3, and dispersed WOx species on ZrO2 surfaces. UV−visible absorption edge analysis, CO2 chemisorption, and Raman spectroscopic results show that three distinct regions of WOx coverage on ZrO2 supports appear with increasing WOx surface density:  submonolayer region (0−4 W nm-2), polytungstate growth region (4−8 W nm-2), and polytungstate/crystalline WO3 coexistence region (>8 W nm-2). The structure and catalytic activity of WOx species on ZrO2 is controlled only by WOx surface density (W nm-2), irrespective of the WOx concentration, oxidation temperature, and ZrO2 surface area used to obtain a particular density. The submonolayer region is characterized by distorted octahedral WOx species that are well dispersed on the ZrO2 surface. These species show a constant absorption edge energy, they are difficult to reduce, and contain few a...

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Structure and Electronic Properties of Solid Acids Based on Tungsten Oxide Nanostructures

Electrochromic colour centres in amorphous tungsten trioxide thin films

Short range and medium range order of WO3 and MoO3 thin films have been investigated. The amorphous structure of these thin films has closely related topology. It is found that there is a temperature range where these materials form microcrystalline state of WO3 and MoO3. X-ray diffraction and Raman scattering data show that the structure of MoO3 microcrystals is different from the structure of bulk MoO3.

Structure of amorphous thin films of WO3 and MoO3

We performed, for first time, ab initio calculations for the ReO2-terminated ReO3 (001) surface and analyzed systematic trends in the ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surfaces using first-principles calculations. According to the ab initio calculation results, all ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surface upper-layer atoms relax inwards towards the crystal bulk, all second-layer atoms relax upwards and all third-layer atoms, again, relax inwards. The ReO2-terminated ReO3 and ZrO2-terminated SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) surface band gaps at the Γ–Γ point are always reduced in comparison to their bulk band gap values. The Zr–O chemical bond populations in the SrZrO3, BaZrO3, PbZrO3 and CaZrO3 perovskite bulk are always smaller than those near the ZrO2-terminated (001) surfaces. In contrast, the Re–O chemical bond population in the ReO3 bulk (0.212e) is larger than that near the ReO2-terminated ReO3 (001) surface (0.170e). Nevertheless, the Re–O chemical bond population between the Re atom located on the ReO2-terminated ReO3 (001) surface upper layer and the O atom located on the ReO2-terminated ReO3 (001) surface second layer (0.262e) is the largest.

https://www.mdpi.com/2073-4352/10/9/745/pdf

Comparative Ab Initio Calculations of ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) Surfaces

Reactive dc magnetron sputtering of W was performed in a plasma of Ar+O2 with and without CF4 addition and substrate bias. Structural studies by atomic force microscopy, X‐ray diffraction, infrared reflectance spectroscopy, and Raman spectroscopy indicated that the electron e bombardment associated with a positive substrate bias led to grain growth and partial crystallization while maintaining a high density of W=O double bonds presumably on internal surfaces. Electrochemical measurements showed that the durability under extended Li+ intercalation/ deintercalation was excellent for e‐bombarded oxide films and poor for oxyfluoride films. Spectrophotometric studies of the electrochromism yielded that the color/bleach dynamics was slow for the e‐bombarded oxide but fast for the oxyfluoride. The range of optical modulation was large. Tandem films, with a thin protective layer of e‐bombarded oxide covering a thicker oxyfluoride layer, were able to combine rapid dynamics with good durability.

Electrochromism of fluorinated and electron‐bombarded tungsten oxide films

Tungsten oxyfluoride films were prepared by reactive dc sputtering in plasmas containing O2+CF4 The deposition rate was large, particularly when chemical sputtering was promoted by heating the target The films could show large charge insertion/extraction and high coloration efficiency

J. Gabrusenoks

Papers

Electrochromic colour centres in amorphous tungsten trioxide thin films

Structure of amorphous thin films of WO3 and MoO3

Comparative Ab Initio Calculations of ReO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3 (001) Surfaces

Electrochromism of fluorinated and electron‐bombarded tungsten oxide films

Electrochromism in tungsten oxyfluoride films made by chemically enhanced dc sputtering