Investigation of Evaporated Rear Contacts for Al-LBSF Silicon Wafer Solar Cells

Silicon wafer solar cells with a local back surface field (“LBSF”) formed by aluminium are currently intensively investigated for industrial application. The non-metallised rear surface regions of this structure are passivated by a dielectric film, whereby this film receives line or point openings for contact formation. In this work we report on Al-LBSF solar cells with thermally evaporated and screen-printed Al as the rear metal and screen-printed silver as the front contact. The interaction of Al and the locally opened dielectric film is investigated in detail, using techniques such as photoluminescence imaging and scanning electron microscopy. The impacts of the laser patterns used for opening of the dielectric film and void formation at the rear contact are investigated.