Industrial large area n-type solar cells with aluminium rear emitter with stable efficiencies

We present in average 17% efficient large area (156×156mm²) n-type boron-free Cz-Si solar cells with rear Al emitter fabricated in an industrial like environment (average V_oc=627.7mV, J_sc=34.6mA/cm², FF=78.1%). The processing sequences were intentionally kept very close to the conventional p-type firing through SiNx process due to a simple transfer to existing p-type production lines. Single processing steps were optimised or slightly adapted to the n-type structure such as FSF formation, edge isolation, paste selection, firing conditions and rear side geometry for cell interconnection. The main advantage of such solar cell structure is that the device is completely boron free and therefore stable in efficiency when exposed to light and in addition show an excellent performance at low light intensity.