4. Summary
We reviewed the issues and solutions of nc-Si:H solar cells.
We believe that proper control of the crystallinity along the film
thickness, reduction of impurity, and improvement in light trapping
are the major areas for improving nc-Si:H component cells. Using
a multi-junction solar cell structure is the path to achieve high
efficiency. United Solar has made significant progress to address
the issues and to improve thin film silicon solar cell efficiency. We
believe that thin film silicon solar cell efficiency will be improved
further and it is a viable technology for large volume PV
manufacturing.