IMPROVED MODELLING OF GRAIN BOUNDARY RECOMBINATION IN POLYCRYSTALLINE SILICON UNDER EXCITATION

In this paper, we present a new approach of grain boundary recombination in polycrystalline silicon solar cell. This approach considers the presence of acceptor-like and donor-like grain boundary trap states in polysilicon, and the dependence of minority carrier density in the bulk part of the grain on the grain size and the bulk diffusion length of minority carriers. Under some conditions, the results of previous analysis can be obtained from this new approach. The effects of grain doping, illumination level, bulk diffusion length and grain size on the barrier height, recombination current density and recombination velocity have been investigated. The obtained results are different from those of Joshi, particularly when the generation rate exceeds 10 19 cm -3 s -1 and the grain size is larger than 100 µm. In addition, our theoretical approach gives results which are in satisfactory agreement with the experimental data.