Enhanced Bifacial III–V/Silicon Multijunction Solar-Cell-Based Promising Structure of c-Si Bottom Cells

We present a structural design for a four-terminal III–V/crystalline silicon (c-Si) multijunction (MJ) device based on optimized bifacial illumination. The proposed configuration consists of a triple-junction top cell incorporating gallium indium phosphide (GaInP), indium gallium arsenide (InGaAs), and germanium (Ge), paired with a tunnel oxide passivating contact (TOPCon) as the bottom cell. The bifacial TOPCon cell effectively enhances the transmission of albedo-reflected light into the c-Si absorber, delivering superior performance compared to conventional heterojunction cells. With an additional rear illumination of 0.3 sun, the bottom cell efficiency increases by 9.61%. Bifacial illumination enhances the overall efficiency of the MJ device by 20.77% compared to the monofacial device. With the power conversion efficiency (PCE) of bifacial GaInP/InGaAs/Ge/TOPCon MJ devices reaching 35.70%, this design demonstrates significant potential for advancing high-efficiency bifacial solar cell technologies.