High-efficiency hybrid solar cell with a nano-crystalline silicon oxide layer as an electron-selective contact

The efficiency of silicon heterojunction solar cells is limited by various factors including low surface passivation, parasitic absorption, and recombination losses. Herein, the surface passivation quality of crystalline silicon solar cells is improved by a hybrid passivation structure including a silicon heterojunction contact at the front side and a stack of tunneling oxide with n-type nano-crystalline silicon oxide (nc-SiOx(n)) passivating contact at the rear side. A passivation contact with thin silicon oxide (SiO2) and poly-silicon was previously proposed to enhance the rear surface passivation. In our study, the poly-silicon layer is swapped with the nc-SiOx(n) layer to improve the effective surface passivation, electrical properties, recombination losses, and carrier selectivity. The hybrid passivation structure shows significant passivation improvement with lifetime (tau(eff)) of 2696 mu s and implied opencircuit voltage (i-V-oc) of 735 mV as compared with both-sides traditional silicon heterojunction (1650 mu s, 719 mV) and tunneling passivation contact (2146 mu s, 725 mV). The hybrid solar cell shows a potential performance as; open circuit voltage (V-oc) = 724 mV, short circuit current (J(sc)) = 38.95 mA/cm(2), fill factor (FF) of 75.9%, efficiency (eta) = 21.4%. However, there is room to further improve the overall cell performance.

Automated summary

The efficiency of silicon heterojunction solar cells is improved by a hybrid passivation structure with a silicon heterojunction contact and a tunneling oxide layer containing n-type nano-crystalline silicon oxide. The hybrid solar cell shows significant improvement in passivation quality and electrical properties, resulting in higher efficiency and better carrier selectivity.