Screen printable, non-fire-through copper paste applied as busbar metallization for back contact solar cells

In this work we metallize the busbars of n-type Zebra IBC cell with a low temperature curable copper based metallization paste. We show that the properties of Cu busbars such as line resistance are similar to comparable Ag based products, and that Zebra IBC cells with Cu busbars feature the same efficiencies as the Ag metallized reference cells. Furthermore, and most importantly, initial climate chamber tests indicate that the silicon bulk material is not contaminated by Cu diffusing from the cells surface even after TC600 and DH3000. However, the paste still shows insufficient adhesion on the substrate surface. This issue is visible in peel force tests and also in climate chamber tests, mainly temperature cycling tests.