The influence of contact geometry and sub-contact passivation on the performance of screen-printed Al₂O₃ passivated solar cells

This paper evaluates possibilities to passivate the semiconductor-metal interface present at the contact sites of large-area PERC-type solar cells to minimize recombination losses at the rear side. It focuses on the contact and BSF formation by local alloying of screen printed Al in a belt furnace process and methods to limit the detrimental lateral Si transport away from the contact sites. The influence of different contact geometries and the resulting local BSF formation on the IV performance on cell level is assessed. For this purpose, 125×125 mm2 p-type Cz-Si solar cells are processed with a screen printing based solar cell process where Al2O3 is used as rear side dielectric and a variety of rear contacting patterns is implemented