Industrial N-type PERL cells with screen printed front side electrodes approaching 21% efficiency

We discuss the enhancements of firing stable fPassDop technology for n-type passivated emitter and rear locally diffused (PERL) silicon solar cells. We investigate modifications of the SiNX based layer by adjusting the nitrogen content. By modifying the passivation layer stack, we achieve higher doping concentrations after laser doping, which is beneficial for rear electrode contact formation. We also show that we find less nitrogen in the point contacts after laser processing when using the updated layer system. Solar cells results confirm these findings: those using the adapted passivation layer, yield lower ohmic losses as well as less scattering in the fill factor. Cell efficiencies of 20.9% and open circuit voltages of 672 mV are achieved.