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Journal of Solar Energy Research Updates

Articles

Vol. 1 No. 1 (2014)

Passivating Silicon Grain Boundaries with Small Polar Molecules for Photovoltaics

DOI
https://doi.org/10.15377/2410-2199.2014.01.01.2
Submitted
September 12, 2014
Published
2014-09-12

Abstract

Grain boundaries (GBs) play a major role in determining the device performance of in particular polycrystalline thin-film solar cells. Hydrogen has traditionally been applied to passivate defects at GBs. However, hydrogenated films are subject to light-induced degradation effects. In this study, we took a novel approach to passivating GBs in multicrystalline silicon (mc-Si) wafers with small polar molecules. We found an excellent correlation between the grain misorientation, electrical resistance across GBs, and passivation effectiveness. In particular, the charge transport across GBs was greatly enhanced after the wafers were properly treated in our polar molecule solutions; the sheet resistance can be reduced by up to more than one order for large-angle random GBs. The results were explained to be due to the effective charge neutralization and passivation of polar molecules on localized charge states at GBs. These findings may help us achieve high-quality materials at low cost for high-efficiency solar cells by enhancing carrier transport and minimizing carrier recombination.

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