Creating cheaper, more flexible, and more efficient solar devices

Contact Electrification (CE), though a familiar everyday phenomenon and long studied, is still poorly understood. Hence, it is crucial to understanding more in detail the fundamental understanding of the phenomenon and the nature of charge carriers when transferred due to CE. Recent work has shown that CE creates a random 'mosaic' of static charges on the surface of two materials that are brought into contact and then separated, challenging old assumptions of one object charging uniformly positive and the other uniformly negative. We investigate the repeatability of these results in ambient conditions using a new experimental technique. Scanning Kelvin Probe Force Microscopy (SKPFM) is used to measure with nanoscale resolution the pattern of surface charge on a glass surface in which evaporated gold electrodes lay parallel. The surface potential in the glass region, between the two electrodes, is a sum of the known potential bias from the electrodes and the potential due to unknown static surface charge. After subtracting off the potential due to the electrodes, we compare the surface charge pattern of the glass region before and after stamping the substrate with PDMS. These results may help us understand and control the origin of CE in electronic devices or when handling dry powders.

The work was supported as part of the PHaSE Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, and was also partly supported by the Xerox University Affairs Committee.