Effect of passivation process in upgraded metallurgical grade (UMG)-silicon solar cells

We have investigated the effect of high-pressure pure hydrogen annealing (HPHA) for upgraded metallurgical grade (UMG)-silicon solar cell in order to obtain cost-effective high-efficiency cell using post-metallization anneal at a relatively low temperature. We have observed that high-pressure pure hydrogen annealing effectively passivated the defects and improved the minority carrier lifetime, series resistance and conversion efficiency. It can be attributed to significantly improved hydrogenation in high-pressure pure hydrogen process. This improvement can be explained by the enhanced hydrogenation of silicon solar cell with antireflection layer due to hydrogen re-incorporation. The results of this experiment represent a promising guideline for improving the high-efficiency solar cells by introducing an easy and low cost process of post-hydrogenation in optimized condition.