A Crystalline Metallic Copper Network Application Film Produced by High-Temperature Atmospheric Sintering

We show the first production of a copper (Cu) application film (AF) consisting of a novel network of crystalline metallic Cu embedded with copper-phosphorus-oxygen glasses (Cu-2(PO4) and Cu2P2O7) to provide new feedstock materials for crystalline silicon (Si) photovoltaics (PVs). The Cu crystal network was preferentially grown in AF, and thus, a Cu AF with low-electrical resistivity was formed in air at elevated temperatures of >= 450 degrees C by using a copper-phosphorus (Cu-P) alloy paste as a starting material for the sintering. The Cu-P alloy had the role that governed deoxidization of a cuprous oxide, which was formed on heating during the sintering, by virtue of a concurrent oxidation of the Cu phosphide at elevated temperatures. Our results may open the way to the widespread use of atmospherically sintered Cu AFs for mass-production of next-generation crystalline Si PVs.