High efficiency n-type Si solar cells on Al2O3-passivated boron emitters

In order to utilize the full potential of solar cells fabricated on n-type silicon, it is necessary to achieve an excellent passivation on B-doped emitters. Experimental studies on test structures and theoretical considerations have shown that a negatively charged dielectric layer would be ideally suited for this purpose. Thus, in this work the negative-charge dielectric Al 2O3 was applied as surface passivation layer on high-efficiency n-type silicon solar cells. With this front surface passivation layer, a confirmed conversion efficiency of 23.2% was achieved. For the open-circuit voltage Voc of 703.6 mV, the upper limit for the emitter saturation current density Joc, including the metalized area, has been evaluated to be 29 fA/cm2. This clearly shows that an excellent passivation of highly doped p -type c-Si can be obtained at the device level by applying Al2O3.