10:00 〜 10:15
▼ [16a-A304-3] Assessing Silicon Nanowires as a Bottom Cell Material for III-V Multijunction Solar Cells using Thin InGaP/GaAs Filter
キーワード：silicon, nanostructure, concentrator
One of the main challenges of III-V based multijunction solar cells (MJSCs) is the high cost due to the rarity of III-V materials. To investigate low-cost, low-bandgap materials that can be in tandem with III-V solar cells without fabricating the whole device, one may use a III-V filter on top of a solar cell containing the candidate material. Silicon-based nanostructures, such as silicon nanowires (SiNWs), are attractive candidates because they have better light trapping and require shorter charge separation distance in the junction than their planar counterpart. In this work, we evaluated SiNW solar cell if it is a suitable bottom cell candidate for III-V MJSCs. This was done by placing it under InGaP/GaAs 2J filter during various characterization methods. Particularly, current-voltage (J-V) characteristics curves and external quantum efficiency (EQE) were obtained. The JSC produced in SiNW reduces to 3.46 mA/cm2 under 2J filter because most of the current were absorbed by the filter. Consequently, the SiNW solar cell efficiency dropped by about 4.98%. These results agree with the JSC derived from EQE, in which the slight difference with the JSC from the J-V curve can be attributed to the difference in lamp sources used during measurements. If SiNW is used as a bottom cell in InGaP/GaAs//SiNW triple junction solar cell (3JSC), in which a typical tandem III-V solar cell produces 10 to 14 mA/cm2 at 1 sun, SiNW is expected to limit the 3J current, and therefore, the conversion efficiency. To make SiNW a more desirable bottom cell material, strategies such as passivation, two-step H2 annealing, or amplifying the luminescent coupling effect towards it are then suggested to reduce the anticipated current mismatch with the InGaP/GaAs tandem.