Novel metal jet printing technique for the front side metallization of highly efficient industrial silicon solar cells

A new technique for the front side metallization of silicon solar cells is presented, based on the idea to form a two-layer contact structure. The first layer needs to have low contact resistance and good mechanical adhesion to the silicon surface; the second layer, which is formed by light-induced plating requires high line conductivity. If the first layer is sufficiently narrow, excellent aspect ratios can be achieved. This paper focuses on the creation of the first layer with a metal aerosol jet printer. A metal containing aerosol is focused via a second surrounding gas stream through a nozzle onto the substrate, which reduces clogging significantly. Another advantage of this non-contact printing technique is that the width of the deposited line is smaller than the outlet diameter of the nozzle. Fine and continuous lines with a width of 30 µm were printed using a nano-particle ink. As the adhesion of these layers was not sufficient, a commercially available screen-printing paste for solar cell metallization was modified and tested. 50x50 mm2 multicrystalline silicon solar cells were processed, achieving efficiencies up to 16.4% with an Al-BSF.