A modified model for large grain multicrystalline silicon used for solar cells

The large grain multicrystalline silicon for large scale terrestrial solar cells application has been well recognized, it shares with single crystal silicon numerous desirable physical and chemical properties such as abundance, low toxicity and stability, but the electrical behavior of multicrystalline silicon is different slightly than single crystal silicon. The electrical behavior of multicrystalline silicon is shown to be influenced by the properties of the grain boundaries, the study of the grain boundaries is very important for improving the efficiency of multicrystalline silicon solar cells. Hence, modeling the electrical properties of large grain multicrystalline silicon and their dependence on dopant concentration becomes very important for the proper design of solar cells and good understanding of multicrystalline silicon solar cells under illumination. In this paper, a new phenomenological model based on a combination of dopant segregation, carrier trapping and carrier reflection at grain boundaries for large grain multicrystalline silicon used for solar cells is developed, the grain boundaries are modeled by high-order cosine barriers. The model of the high-order cosine barriers is found to more accurately model the practical silicon grains in the body. The result shows that, as the grain size is increased, the resistivity approaches that of single crystalline silicon, although it always remains slightly higher at the same dopant concentration; and as the dopant concentration is increased, the resistivity approaches that of single crystalline silicon, although it always remains higher at the same grain size.