0.4% absolute efficiency gain of industrial solar cells by laser doped selective emitter

The formation of selective emitter with lower doped areas between the contact fingers and higher doped areas beneath the front side metallization increases the efficiency ¿ of crystalline silicon solar cells. The efficiency increases as a result of higher open circuit voltage and enhanced short circuit current density. The ipe laser doping process offers an elegant and reliable approach for the local formation of selective emitters. We use only one additional laser processing step after furnace diffusion. Thus, this patented process is easily integrated into an industrial production line without changing previous and subsequent processing steps. The phosphor silicate glass (PSG) layer, already grown on top of the emitter during furnace diffusion, serves as doping precursor. A laser locally melts the emitter surface and additional phosphorus atoms diffuse from the PSG layer into the emitter, increasing the doping concentration. This single additional processing step increases the efficiency ¿ of monocrystalline industrial solar cells by ¿¿ = 0.4% absolute.