Effects of grain boundaries on the performance of polycrystalline silicon solar cells

摘要

A comprehensive carrier recombination model under optical illumination near grain boundaries (GBs) is proposed by considering the asymmetric Gaussian energy distribution of GB interface states model. A new recombination velocity S(L n) is proposed to study the dependence of effective diffusion length of minority carriers on grain size and GB interface state density. The dependence of GB space charge potential barrier height (qV g), the recombination velocities, and polycrystalline silicon (PX-Si) solar cell parameters on grain size, illumination level, and GB interface state density have also been studied. It is observed that the efficiency of solar cells is mainly determined by the potential barrier height qV g. Considering the effect of vertical GBs in the junction depletion region of a solar cell, it is also observed that their effect is smaller in the small grain size range as compared to that in the large grain size range. A reasonably good agreement is obtained between the theoretical predictions and the available experimental data.