Caleb Okrucky, 

Title:

In-situ Electron Microscopy of Full-Stack Silicon Solar Modules Reveals the Nanoscale Source of a Vital Degradation Mode

Abstract:

Society is moving towards a greener future with renewable energy, but some solar technologies are not as durable as predicted. One failure point in silicon solar cells concerns the delicate photovoltaic silicon material. The silicon is known to be susceptible to degradation by sodium migration. To quantify these effects, we employed scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to generate spatially resolved chemical and morphological maps of the glass/EVA interface in a full-stack silicon solar module.
We found that sodium depletion was location specific and occurred at different rates or not at all. This discrepancy indicates a difference in the underlying kinetics. Intensity line-scans extracted from AZtec NanoAnalysis software and processed through ImageJ and OriginPro software revealed that the cover glass in in-fact the likely source of poisoning sodium. Given that the depletion kinetics are location specific, further work is underway to investigate nanoscale region behaviors using electron energy loss spectroscopy (EELS), cryo scanning transmission electron microscopy (STEM), and atomic resolution energy-dispersive X-ray spectroscopy (EDS).