Fabrication of an inkjet-printed seed pattern with silver nanoparticulate ink on a textured silicon solar cell wafer

Abstract

In this study, the possibility of using inkjet printing in the fabrication of a conductive seed pattern on a textured silicon solar wafer is investigated. Firstly, solar cell wafers were coated with a hydrophobic solution. It was found that the surface texture of a solar cell wafer causes a slight increase in the contact angle of silver nanoparticulate ink by 7.5° due to a weak Cassie–Baxter wetting state. After selective laser ablation of the hydrophobic coating and the SiN x layer in preparation for the surface energy-patterned finger electrode regions, silver nanoparticulate ink was deposited with a piezo drop-on-demand inkjet print head. Because the threshold laser fluence for the ablation of the hydrophobic coating is lower than that for the SiN x layer, the effective width of a surface energy-patterned finger electrode region with the Gaussian laser beam profile was found to be wider than the actual width of the SiN x -ablated region. Although this initially results in a widened deposition of silver nanoparticulate ink, the subsequent drying of silver nanoparticulate ink is found to cause a reduction of line width of around 6% to 14%. Therefore, the final line width of the seed pattern is the outcome of two opposing phenomena. The physical and electrical characteristics of the seed pattern are as narrow as 58.5 ± 1.2 µm, as thick as 1.81 µm on average and as conductive as 2.72 µΩ cm.