Impurity photovoltaic effect in c-Si solar cells.: A numerical study

A numerical study is made of the impurity photovoltaic (IPV) effect in crystalline Si p-n junction solar cells. Application is made to In impurities whose energy level is at 0.157 eV above the valence band edge. The numerical resolution of Poisson's equation and the continuity equations for electrons, holes and defect levels yields the current-voltage curves for different impurity concentrations N-t, from which the short-circuit current density J(sc), the open-circuit voltage V-oc, and the energy conversion efficiency eta is obtained. It is shown that increasing the defect concentration N-t with respect to the background donor concentration leads to an increase of J(sc) but decreases V-oc and eta. A modified defect concentration profile in a p-n-n(+) structure is suggested to extract the maximum benefit from the IPV effect. (C) 1999 American Institute of Physics. [S0021-8979(99)00904-4].