Modeling of the recombination at grain boundaries in preferentially doped polysilicon solar cells

Abstract

Making use of results developed in an earlier paper and according to the theory of Oualid et al., the photovoltaic parameters of a preferentially doped N + P solar cell are studied as a function of the density of interface states ( N t) at the grain boundaries. The results are compared to the ones established with respect to the grain boundary recombination velocity V s (without considering grain boundary recombination theory). The results show that in the case of small recombination at the grain boundaries ( N t < 10 12 cm −2) the variation of the photovoltaic parameters with respect to the density N t is similar to that obtained with the velocity V g. The results also show that, when the density N t is superior to this value, the decrease of the optimum base doping giving the maximum efficiency of the cell with respect to the grain width (in a log-log plot), is no longer linear. This result contradicts the one of Dugas and Oualid.