LFC on screen printed aluminium rear side metallization
In this paper we report about first results regarding laser fired contacts (LFC) on an optimized screen printed aluminum rear side layer and compare it with our ""standard"" LFC procedure on evaporated aluminum layers. First of all, the influence of the laser pulse energy, pulse duration and amount of pulses on the resistance of one contact is evaluated. Since this value depends strongly on the size of the contact also the recombination losses in the contact area have to be considered in order to compare and qualify LFC contacts comprehensively. We have achieved cell efficiencies > 18.0 % on industrial like processed wafers, which underlines the potential of this approach. Finally, a 20.5 % efficiency solar cell with an aerosol printed front metallization manufactured on laboratory scale is presented, which is the best value ever reported for solar cells with fired front and back side metallization.