Coating process could deposit uniform nanofilms on surfaces

The technique, developed by researchers at Pennsylvania University’s School of Engineering and Applied Science, will be particularly useful for coating electrodes.

Making uniform coatings is a common engineering challenge and, when working at the nanoscale, even the tiniest cracks or defects can be a big problem.

Notably, high-end devices, such as certain types of solar cells, have electrodes composed of nanoparticle films that conduct electrons, but cracks in the films act as insulators. Adding a binder to the films would only compound the problem since these binders are usually polymers, which are insulators.

The ubiquity of cracking in this context, however, means that researchers know the ‘critical cracking thickness’ for many materials. The breakthrough came when the Pennsylvania team tried making a film thinner than this threshold, then stacking the films together to make a composite of the desired thickness.

‘I was thinking about how, in the painting of buildings and homes, multiple coats are used,’ said study lead Jacob Prosser of Pennsylvania. ‘One reason for that is to avoid cracking and peeling. I thought it could work for these films as well, so I gave it a try.’