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

Abstract

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 ${\mathrm{Al}}_2{\mathrm{O}}_3$ 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 $V_{\mathrm{oc}}$ of $703.6\mathrm{mV}$ , the upper limit for the emitter saturation current density $J_{0e}$ , including the metalized area, has been evaluated to be $29\mathrm{fA}∕{\mathrm{cm}}^2$ . This clearly shows that an excellent passivation of highly doped $p$ -type $c\text{-}\mathrm{Si}$ can be obtained at the device level by applying ${\mathrm{Al}}_2{\mathrm{O}}_3$ .