Microstructured silicon with two impurity bands for solar cells

Abstract

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to have an impact on terrestrial photovoltaic technology significantly. We investigated microstructured silicon formed by irradiating the surface of a Si wafer with femtosecond laser pulses in the presence of a sulfur-bearing gas. It is widely believed that microstructured silicon is a potential material for efficient multi intermediate bands silicon solar cell. Using a four-band model, the loss of sunlight for silicon with two different chalcogenide impurity bands was analyzed, and the levels of the minimum loss of sunlight can be found. Then the effect of the position at which the intermediate bands that have minimum sunlight loss rate on the theoretical conversion efficiency of the corresponding solar cell was discussed with the Detailed Balance Theory. After that, the influence of impact ionization on the efficiency of four-band Solar Cells was analyzed in detail. Finally, problems that need to be resolved in making intermediate band solar cell based on femtosecond laser microstructured silicon are pointed out with great emphasis.