Characterzing aerosol Jet^® multi-nozzle process parameters for non-contact front side metallization of silicon solar cells

Abstract

High efficiency 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. A multi-nozzle print head was developed to increase throughput to a level comparable to screen-printing. A modified screen-printing paste was used to print a seed layer for collector lines on 156 × 156 mm multi-crystalline silicon wafers. By adjusting print process parameters such as gas flow rates, operating temperature, and nozzle orifice openings, line width was controlled over a range of approximately 35-70 microns. In parallel, a single-nozzle print head was developed for printing busbars of around 1 mm width in a single step.