August
Picture of the Month - August 2017
Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.
Monitoring hydrogen diffusion in polycrystalline WO3 using in-situ transmission spectroscopy
The insertion of ions and electrons in tungsten trioxide (WO3) results in a reversible coloration of the material. Due to these electrochromic properties WO3 is used in a variety of applications, such as smart windows. However, the coloration behavior and the corresponding transport mechanisms of the involved charge carriers are not completely understood. The figure shows the space- and time-resolved in-situ investigation of the transmission change of a polycrystalline WO3 thin film during the lateral diffusion of hydrogen in WO3. The thin film was micro-structured with a transparent polymer (PMMA) film to insert protons electrochemically into the thin film only in a small bar area. Due to the resulting concentration gradient, the charge carriers are diffusing inside the WO3 thin film leading to a coloration change. The space-resolved behavior of the transmission change reveals a concentration dependence of the diffusion coefficient of hydrogen in polycrystalline WO3 thin films.
This picture was submitted by Simon Burkhardt (Prof. Klar's Group).