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High Accuracy, High Aspect Ratio Metallization on Silicon Solar Cells Using a Print on Print Process
T. Falcon
Screen Printing, Solar Cell-Efficiency, Aspect Ratio, Metallization, Metallisation
Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic: Manufacturing Issues and Processing
Event: 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain
Session: 2CV.1.66
1651 - 1655
ISBN: 3-936338-26-4
Paper DOI: 10.4229/25thEUPVSEC2010-2CV.1.66
0,00 EUR
Document(s): paper


One of the most fundamental losses in silicon solar cell efficiency, and therefore a serious obstacle to achieving grid parity, is the shading of the wafer’s surface by the frontside metallization grid. It is now well understood that the creation of higher aspect ratio frontside conductors will expose more silicon to sunlight, without increasing the conductor’s electrical resistance, thereby enhancing conversion efficiency [1]. Whilst there are many viable technologies for creating such conductors, few of these have made it to high volume manufacturing. One simple, but highly effective method is known as “Print on Print” or PoP. The technique requires the printing of a second metallization grid directly on top of a previously printed and dried grid. This paper will describe some of the most important aspects of PoP process development. Our approach will be to test various screen mesh types, emulsion thicknesses, aperture widths, paste types and process parameters, thereby empirically defining the optimum PoP process. The benchmark will be a standard (but high performance) single print process and the results of this work will show measurable improvements in conductor aspect ratio and efficiency over the benchmark.