Effect of Grain Size on Spectral Response and Eternal Quantum Efficiency of a Polycrystalline Bifacial Silicon Solar Cell

In this work, a 3D theoretical study of a grain columnar model of a bifacial silicon solar cell under monochromatic illumination, is done. From the continuity equation of the photocreated minority carriers in the base of the cell, we determined the expression of the minority carriers’ density according to the wavelength, the grain size, the recombination velocity at grain boundaries and the recombination velocities at the junction and the rear side. By the use of the minority carriers’ density, the expressions of the photocurrent density, the spectral response and the external quantum efficiency have been deduced. We noted an improvement in spectral response and quantum efficiency with the increase of the grain size. Although, the recombination velocity at the grain boundaries leads to a decrease in spectral response and quantum efficiency; what corresponds to a poor quality of the solar cell since there is a degradation of its intrinsic properties.