Abstract
The effect of tapered shape on electrical properties of heterojunction silicon nanowire (SiNW) solar cells was simulated with a two-dimensional quantum device simulator. When the quantum effect was taken in account, opencircuit voltage (Voc) and fill factor (FF) of heterojunction SiNW solar cells were drastically improved from 390 to 862 mV and from 0.662 to 0.795, respectively. This is due to the bandgap widening and the enhancement of electric field in the intrinsic SiNW. When a top side diameter (d1) of the SiNW was set at 2 nm and a bottom side diameter (d2) was varied from 2 to 6 nm, short-circuit current density (Jsc) was drastically increased from 6.96 to 30.8 mA/cm2. The main reason is the absorption enhancement due to a tapered shape with a graded refractive index. Ultimately, conversion efficiency was monotonically increased with increasing d2 in the range from 2 to 6 nm. The quantum size effect and the tapered shape can enhance conversion efficiency of heterojunction SiNW solar cells.
Published Version
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