abstr19

Thin films of electrochromic materials such as tungsten trioxide (WO3) are
essential components of electrochromic devices such as “Smart Windows.”
The transport of charge carriers in WO3 thin films has been investigated
intensively over the past decades, yielding a wide spread of diffusion coef-
ficients of hydrogen in WO3. Most of those analyses are based on measurements
by electrochemical methods. However, such analyses are only
applicable and the results reliable in cases where diffusive transport is the
rate-determining process. Here, WO3 thin films of different morphology
are prepared by electron-beam evaporation of WO3 powder. The combined
lateral diffusion of protons and electrons is investigated inside amorphous
and polycrystalline WO3 thin films by in situ transmission spectroscopy
x 3 3 during electrochemical hydrogen insertion into the film. The insertion of
the protons is carried out locally and lateral diffusion of H takes place in
the film plane. The induced change of the film absorbance at a wavelength
of (637 ± 15) nm is monitored and spatially and temporally resolved. The
results reveal a concentration-dependent diffusion process of hydrogen in
both, amorphous and polycrystalline WO3, which are critically discussed in
the context of existing data from literature.

 Back to homepage