Direct writing for silicon wafer solar cells

Abstract

This thesis investigates the application of drop-based direct writing techniques for the fabrication of advanced silicon wafer solar cells. In particular inkjet and aerosol jet printing are investigated for patterning the rear dielectric films of aluminium local back surface field (Al-LBSF) solar cells. A new method is presented to geometrically confine directly deposited features on hydrophilic rough surfaces. The direct patterning technique is applied to the fabrication of Al-LBSF solar cells, resulting in cell efficiencies of up to 18.5%. In addition, the etching of silicon in hydrofluoric acid (HF) is investigated in detail. HF etching is commonly used to remove masking layers in the Al-LBSF solar cell fabrication process, due to its excellent selectivity in etching dielectric films over silicon. This work shows that this selectivity does not necessarily hold for highly n-type doped silicon surfaces, which has major consequences for the solar cell fabrication process.