Optimum design of InGaP/GaAs dual-junction solar cells

We designed the InGaP/GaAs dual-junction solar cells by optimizing short-circuit current matching between top and bottom cells using a Silvaco ATLAS. The relatively thick base layer of top cell exhibited a larger short-circuit current density (J_sc) while the thicker base layer of bottom cell allowed for a smaller J_sc. A maximum J_sc of 11.86 mA/cm² was obtained, leading to the increased conversion efficiency. The base thicknesses of top InGaP and bottom GaAs cells were optimized at 650 nm and 2 mum, respectively. For the optimized solar cell structure, the J_sc = 11.86 mA/cm², V_oc = 2.32 V, and fill factor = 88.42% were obtained under AM0 illumination, exhibiting a conversion efficiency of 24.27%. The effect of tunnel diode structure, i.e, GaAs, AlGaAs, and InGaP, on the characteristics of solar cells was investigated.