Silicon solar cells with screen printed-front contact and dielectrically passivated, laser-fired rear electrode

With respect to cost reduction the main future effort in silicon solar cell technology is to manufacture solar cells with highest possible efficiencies on the thinnest possible wafers ensuring a maximum production yield. The laser-fired contact (LFC) technology that has been developed at Fraunhofer ISE allows the implementation of a dielectrically passivated rear electrode in an easy way and therefore fits these main industry requirements. In this paper the transfer of the LFC-technology to solar cells with screen-printed front end process is reported. Laboratory type solar cells with laser-fired rear electrode have been processed on 170 ?m thin, float-zone silicon (1 ohm cm) and Czochralski silicon (3-6 ohm cm) wafers. On 10x10 cm2 FZ-substrates efficiencies up to 17.1 % have been reached compared to 16.4 % of standard screen-printed solar cells with aluminium back surface field. On 125 mm pseudosquare FZ-wafers even an efficiency of 17.7 % has been achieved. These results clearly demonstrate the compatibility of the LFC approach to the today industrial standard screen-printed solar cell technology. Keywords: laser processing, back contact, manufacturing and processing.