Influence of dislocations on electrical properties of large grained polycrystalline silicon cells. I. Model

Abstract

The influence of the density (Ndis) and of the recombination activity (Sd) of dislocations on the photocurrent (Jsc), the spectral dependence of Jsc and the effective electron diffusion length (Leff) of a P+-N junction solar cell are computed by means of a model which makes use of the Green’s function method. In this model Sd is the surface recombination velocity of the space-charge cylinder surrounding the dislocation line and the dislocations are assumed to be perpendicular to the illuminated surface of the cells and homogeneously recombining. The results obtained indicate that the values of Jsc and their spectral variations, as well as values of Leff, are dependent on both Ndis and Sd, especially when Ndis and Sd are larger than 103 cm−2 and 104 cm s−1, respectively. The base thickness (d) of the cells and the value of electron diffusion length (Ln) in the undislocated regions of the wafers are also introduced in the model as independent parameters.