High efficiency interdigitated back contact silicon solar cells

Interdigitated back contact (IBC) silicon solar cells with 25.6% efficiency at 10 W/cm/sup 2/ and 24.4% at 30 W/cm/sup 2/ were fabricated. The authors report on the technological process, which produces a high effective carrier lifetime in the bulk (780 mu s), and on the characterization of the cells. The front side of these cells is textured and has a very efficient polka-dot floating tandem junction. IBC and point-contact (PC) cells are fabricated on the same substrate and their efficiencies are compared. The possibility of reaching 29% efficiency at 300X is shown.