HIGH ASPECT RATIO FINE GRIDLINE FOR FRONT SIDE METALLIZATION OF INDUSTRIAL SILICON SOLAR CELLS BY DIRECT PRINTING

摘要

This work presents a direct printing technology and an enabling tool for patterning high aspect ratio fine gridlines for front side metallization on silicon solar cells. The conductive gridlines were formed by a one-step, non-contact approach at high speeds using a modified screen printable paste. The fired gridline is as small as 40μm wide and more than 30μm tall, which gives an aspect ratio of 0.75 or more. Due to less shading and well maintained gridline current carry capability, the cells with direct printed metallization gridlines showed ～0.5% absolute efficiency increase compared to the screen printing baseline cells. This study also investigated the impact of the direct printed gridlines on Isc, Voc, FF. For the three direct printed Ag gridline counts chosen (63, 87, and 113), the average efficiency was 18.7-18.8% (compared to 18.3% for the screen-printed control). The common efficiencies for each gridline count are seen as a balance of short circuit current (J_(sc)) and fill factor (FF). Cost analysis shows that with 63 direct printed gridlines, the decreased Ag consumption paired with the increase in power output can lead to 20% Ag cost savings.