Microscopic Description of Light Induced Defects in Amorphous Silicon Solar Cells

Using a combination of quantum and classical computational approaches, we model the electronic structure in amorphous silicon in order to gain an understanding of the microscopic atomic configurations responsible for light-induced degradation of solar cells. We demonstrate that regions of strained silicon bonds could be as important as dangling bonds for creating traps for charge carriers. Further, our results show that defects are preferentially formed when a region in the amorphous silicon contains both a hole and a light-induced excitation. These results are consistent with the puzzling dependencies on temperature, time, and pressure observed experimentally.