EFFECTS OF SODIUM ON POLYCRYSTALLINE CU(IN,GA)SE-2 AND ITS SOLAR-CELLPERFORMANCE

The promising new generation of solar cells based on CIGS (Cu(I,Ga)Se- 2) exhibits behavior differing from that of earlier cells because of c hanges in the method of preparation, leading, among other things, to a difference in sodium content. A simple defect chemical model is prese nted for the effects of sodium on the surface chemistry and electronic properties of CIGS thin films. The model, based on the well-known cat alytic effect that alkali metals have on surface oxidation of semicond uctors, is shown to be consistent with the experimental data available in the literature.