20 center dot 5% efficient silicon solar cell with a low temperature rear side process using laser-fired contacts

The paper presents a rear side structure for crystalline silicon solar cells, which is processed at a maximum temperature of 220 degrees C. Using two different material compositions for electrical and optical needs, the layer system has excellent passivation properties, enhances light trapping and allows for a good ohmic contact. With this structure we achieve an independently confirmed conversion efficiency eta =20 center dot 5% on a 250 mu m thick silicon solar cell. Due to the fact that the maximum process temperature is 220 degrees C, this layer system enables new solar cell concepts.