Development of Ipa-Free Texturing Processes in Advanced Solar Cell Fabrication

The application of IPA-free alkaline solutions to replace an existing IPA-usage texturization process for the fabrication of advanced silicon solar cells in a large-scale production line is developed and evaluated. A non-IPA additive with KOH solutions was employed and process parameters were modified for texturing 156mm n-type c-Si wafers to produce texture morphologies similar to those with KOH/IPA solutions. The wafers were then made into advanced cells in a heterojunction (HET) solar cell fabrication pilot line. Conversion efficiency of the cells from the IPA-free KOH texturized wafers was compared to the KOH/IPA texturized wafers. Wafers processed in an IPA-free KOH bath with different extents of bath life and in baths with various silicate levels were also evaluated. No noticeable changes in cell performance were observed. Overall, the experiments showed that an IPA-free KOH texturing process can be optimized to integrate with an existing HET cell production line without the need of re-tuning the parameters of subsequent processes nor compromising the cell performance.