Comprehensive comparison of different fine line printing technologies addressing the seed and plate approach with Ni-Cu-plating
The seed and plate approach with subsequent Ni-Cu-Ag light-induced plating is still of high interest for the front side metallization of silicon solar cells. From a technical point of view (shape of the contact fingers, lateral conductivity), the quality of the plated front contacts is considerably higher compared to screen printed contacts. From an economical point of view, this approach offers the potential to reduce silver consumption significantly. Within this work, a fine line seed layer front side grid has been applied using two innovative fine line printing technologies - rotational flexographic printing and inkjet printing. Both technologies achieved an average seed layer finger width < 40 mm, in case of flexographic printing even < 30 mm. The electrical results of the solar cells with inkjet and flexo printed seed layer after Ni-Cu-Ag plating have been compared to state-of-the-art screen printed solar cells. The total silver consumption of the seed and plate cells of 15 to 17 mg on the front side is considerably smaller than the screen printed reference cells with approx. 100 mg. Both groups achieved an average conversion efficiency of = 19.1 % which is comparable to screen printed solar cells on the same material.