Aerosol Jet® Printing System for High Speed, Non-contact, Front Side Metallization Helping Improve Efficiencies of Silicon Solar Cells

Abstract

Highly efficient solar cells can be produced by applying the front side metallization in a two-step process. A seed layer is printed followed by an electroplating step to increase thickness and reduce current loss. While traditional screen-printing can be used to print the seed layer, greater benefit is realized by utilizing a direct-write approach to simultaneously reduce the width and thickness of the seed layer. Aerosol Jet Printing is a non-contact direct-write approach that has been shown to have advantages for printing the seed layer. However, the throughput from a typical single-nozzle print head is too low to be useful for production. To increase throughput to a level comparable to screen-printing, a multi-nozzle print head was developed. A modified screen-printing paste was used to print a seed layer for collector lines on 156 x 156 mm2 multi-crystalline silicon wafers. Wafer printing times of approximately 3 seconds/wafer were measured. An average line width of 55.7+/-1.2 microns was measured over 10 wafers printed sequentially. An average line width of 54.5+/-2.0 microns was measured for wafers printed hourly over 10 hours of continuous operation. A Print Head for printing bus bars was demonstrated. Bus bars could likewise be printed with a print time of 3 seconds/wafer.