  This paper proposes an efficient three-layered p-GaAs/p-CIGS/n-CdS (PPN), a
unique solar cell architecture. Copper indium gallium selenide (CIGS)-based
solar cells exhibit substantial performance than the ones utilizing cadmium
sulfide (CdS). On the contrary, CIGS-based devices are more efficient,
considering their device performance, environmentally benign nature, and
reduced cost. Therefore, our paper proposes a numerical analysis of the
homojunction PPN-junction GaAs solar cell structure along with n-ZnO front
contact that was simulated using the Solar Cells Capacitance Simulator
(SCAPS-1D) software. Moreover, we investigated optimization techniques for
evaluating the effect of the thickness and the carrier density on the
performance of the PPN layer on solar cell architecture. Subsequently, the
paper discusses the electronic characteristics of adding GaAs material on the
top of the conventional (PN) junction, further leading to improved values of
the parameters, such as the power conversion efficiency (PCE), open-circuit
voltage (VOC), fill factor (FF) and short-circuit current density (JSC) of the
solar cell. The most promising results of our study show that adding the GaAs
layer using the optimised values of thickness as 5 ({\mu}m) and carrier density
as 1*1020 (1/cm) will result in the maximum PCE, VOC, FF, and JSC of 45.7%,
1.16V, 89.52% and 43.88 (mA/m2), respectively, for the proposed solar cell
architecture.
