A comparison of the behavior of solar silicon material in different production processes

In this paper we show the behavior of four different solar grades and three kinds of CZ silicon subjected to different solar cell fabrication processes. Polycrystalline slices of BAYSIX, HEM, Silso and EFG silicon were used. A standard sequence that does not include reduction of the front and back surface recombination velocities does poorly with all materials. Reducing these contributions to minority carrier recombination leads to cell efficiencies well over 15% for single crystal materials and to the mid 14% range for polycrystalline silicon when a high throughput, low cost production process is used. The high efficiency process produces CZ cells with efficiencies over 19%, and polycrystalline cells over 16%. It is necessary in polycrystalline silicon that the number of low lifetime grains be minimized if the open-circuit voltage is to be maintained.