Influence of the Precursor Annealing on the Cu(In,Ga)Se2 Solar Cell Performance

The stacked CuGa/In metallic precursor thin films were fabricated and annealed at low temperature of 200 degrees C before the selenization for fabricating Cu(In,Ga)Se-2 photovoltaic absorber. The pre-annealing of Cu-In-Ga precursor was found to reduce Cu9Ga4 phase and increase the formation of Cu-16(In,Ga)(9) phase, which may be preferable for the subsequent selenization in terms of homogenizing Ga across the absorber thickness. However, the replacement of In with Ga in the ternary phase produced large amount of free-In, which gave rise to blistered area as shunt paths after the selenization. The performance of solar cell fabricated using the pre-annealed precursor was heavily deteriorated compared to the not-annealed precursor.