Local boron doping for P-type PERL silicon solar cells fabricated by laser processing of doped silicon nanoparticle paste

We present the fabrication of local boron doping for local contacts for p-type PERL solar cells. A boron doped silicon nanoparticle paste is printed onto the passivated rear side of the wafer and is locally diffused into the wafer by an adapted laser process. Thus a local p+ doping is formed and the passivation is opened in a single processing step. After a description of the process and the properties of the local boron doping, fabricated solar cells are discussed. A maximum conversion efficiency of 20.0% is achieved for PERL type solar cells on 6-inch MCz-Si wafers. High fill factors above 79% and high open circuit voltages above 650 mV are observed, highlighting the effectiveness of the local back surface field underneath the rear side point contacts.