Current matching and efficiency optimization in a two-junction nanowire-on-silicon solar cell

Numerical simulation of the photocurrent density is performed for a two-junction nanowire (NW)-on-silicon solar cell under AM1.5G illumination. The photocurrent density is determined for NW diameters from 100-250 nm, period (spacing) from 250-1000 nm, and length of 5 μm. The dependence of photocurrent density on NW bandgap is also determined. For each NW bandgap, the optimum diameter and period are determined to obtain current matching between the top NW cell and the bottom Si cell.