Design and simulation of double-heterojunction solar cells based on Si and GaAs wafers

This article demonstrates the novel designs of Si and GaAs wafer-based double-heterojunction (DH) solar cells using SCAPS-1D simulator. Simple five-layer solar cells are proposed here: cells comprised of a cathode metal layer, three layers of semiconductor materials in the III–V, II–VI and group IV families--and a layer of anode metal. The device structures have been optimized for the analysis of the power-conversion efficiency (PCE) of the Si and GaAs solar cells considering high defect densities at and near each heterojunction. The PCEs predicted are 38% and 38.9% for n -ZnSe/ p -Si/ p + -Al 0.8 Ga 0.2 Sb and n -ZnSe/ p -GaAs/ p + -AlAs 0.9 Sb 0.1 cells, respectively which stay entirely within the PCE limits set by the Shockley–Queisser theory of multi-junction cell. These results reveal that high efficiency and hence cost-effective Si and GaAs wafer-based DH solar cells can be fabricated in the near future.