Screen-printed ribbon growth on substrate solar cells approaching 12% efficiency

Ribbon growth on substrate (RGS) solar cells have been processed at the University of Konstanz using an adapted industrial-type fire-through SiN process. An efficiency of 12.3% has been reached on a 5/spl times/5 cm/sup 2/ cell. This is the highest efficiency obtained on this very promising and cost-effective material using an industrial-type cell process. An important factor for the increase in efficiency was the reduced oxygen concentration of almost an order of magnitude in the current RGS wafer material compared to former RGS material. Enhanced J/sub sc/, V/sub oc/ and L/sub eff/ values in the range of 100 /spl mu/m as well as lifetimes above 4 /spl mu/s demonstrate the potential of the new low oxygen RGS material. Efficiencies well above 13% should be possible, provided a surface texture is applied and shunting mechanism can be avoided.