Silicon solar cells on unidirectionally recrystallized metallurgical silicon

The deposition of a silicon layer containing a p-n junction on a metallurgical silicon substrate has been used for the fabrication of solar cells. The substrate was prepared by the unidirectional solidification of purified metallurgical silicon on a graphite plate, and the active region of the solar cell was deposited by the thermal reduction of trichlorosilane with hydrogen containing appropriate dopants. The current-voltage characteristics of a number of solar cells were measured in the dark and under illumination. The AM1 efficiency of large-area cells (30 cm²) was up to 5.5 percent. When a large-area cell was divided into small-area (5-cm²) ones, the conversion efficiency was found to correlate directly with the dark current-voltage characteristics of, and the structural properties of silicon in, each cell.