GRAIN-BOUNDARY EFFECTS IN POLYCRYSTALLINE SILICON SOLAR-CELLS

The polycrystalline silicon solar cell is divided into four regions: (a) skin (emitter) grain region, (b) skin grain boundary region, (c) grain base region and (d) grain boundary base region. Since the grain base region, having a much larger area than other regions, is the dominant photoabsorbing region in silicon solar cells, the photocurrent and dark current contributions from this region have been computed using two-dimensional analysis with the help of Green's function technique. The contributions from the other regions, being much smaller, have been computed using the usual one-dimensional analysis. The dependence of the short-circuit current and open-circuit voltage of these cells on the different parameters such as grain size, grain boundary potential barrier, grain boundary recombination velocity etc., have also been investigated taking into account the variation of the diffusion length in the grain boundary region. The control of important parameters for the optimization of polycrystalline solar cells is discussed. © 1990.