Metallisation for Silicon Heterojunction Solar Cells

Abstract

In recent years, Silicon Heterojunction Solar Cells (SHJ) have attracted considerable attention for their high efficiency potential at reasonable cost. The processing-sequence consists of thin amorphous-silicon layers deposition for emitter and back-surface field formation on textured silicon wafers. On top of these, transparent conductive oxides (TCOs) are deposited and finally the cells are metalized. Currently the most popular method of metallization is Screen Printing but other methods of pattern deposition are emerging as potential candidates. This paper looks at the relative advancements in the stencil printing technology for SHJ to help achieve high aspect ratio conductor traces. We show that fine lines down to 35 microns and high aspect with aspect ratio of 1:1 at 65 μm width are achievable using low curing temperature paste. We finally show how such contacts can lead up to 20% efficient 2x2 cm2 cells.