Analytical model of photo-conversion in polycrystalline silicon

Polycrystalline Silicon (poly-Si) is widely used for large-volume production of low-cost terrestrial solar cells (SC). Poly-Si grain size and shape essentially determine SC performance and efficiency. In the poly-Si grain, photo-carrier recombination is essentially inhomogeneous and dominates in the region close to the grain boundary (GB). To account for such inhomogeneity, poly-Si was modeled analytically by representing the grains as parallelepipeds or cylinders, and considering three-dimensional (3D) spatial dependence of generation and recombination of electron-hole pairs both in the bulk and at the grain boundaries. The recombination dependence of the polycrystalline material parameters was derived and discussed. SC characteristics calculated by applying the developed 3D analytical formalism are in good agreement with the experimental data available.