Photoluminescence imaging of solar grade mc-Si wafers and solar cells as a tool for efficiency qualification [Poster]

Abstract

The photovoltaic industry is, nowadays, dominated by silicon technology. In the case of multi-crystalline Si (mc-Si) the efficiency losses are mainly caused by the structural defects inherent to the growth, e.g. grain boundaries (GBs), dislocations, and incorporation of impurities. PL imaging (PLi) technique is a promising experimental tool for a fast qualification of mc-Si wafers because permits acquiring in a short time a panoramic view of full wafers. PLi gives information about the presence and distribution of carrier traps, which negatively affect the efficiency. In this work, we analyze the PLi of several solar cells of known efficiencies, observing fear correlation between the colour lookup table (LUT) extracted from the PL images and the solar cell efficiencies. Both, a Si CCD and an InGaAs CCD detectors were used. The images were processed with “Image J” software. The final goal of this approach is to provide a tool allowing a robust prediction of solar cell efficiency from the PL images of mc-Si wafers.