Impurities in the crucible used to case polycrystalline silicon lead to a reduction in the bulk lifetime of the silicon adjacent to the crucible. This effect by plots of cell short-circuit current and diffusion length as a function of distance from the side of the ingot. Lower values obtained near the outer edge result in lower overall cell efficiencies and lower yield of usable silicon from the ingot. It is reported that the use of high-purity crucibles has led to improvements in the efficiencies of 10-cm x 10-cm solar cells due to an increase in bulk lifetime from an average of 90-100 microns up to 130 microns for 1.5-ohm-cm material. Average encapsulated solar cell efficiencies in the range of 12.5 to 13.0 percent are now routinely achieved in production for these 10-cm x 10-cm cells.
19th IEEE Photovoltaic Specialists Conference
- Pub Date:
- Energy Conversion Efficiency;
- Solar Cells;
- Diffusion Length;
- Short Circuit Currents;
- Electronics and Electrical Engineering