Impact of junction position and type on the performance of InGaAs solar cells for multijunction application

We investigated the impact of junction position (front and rear) and type (homojunction and heterojunction) on the performance of InGaAs solar cells, aiming to determine the optimal design of the InGaAs sub-cell for high-efficiency multi-junction solar cells. The key findings include: the front-junction configuration enables efficient carrier collection, resulting in a high J_SC; heterojunctions and the rear-junction configuration contribute to suppress Shockley–Read–Hall recombination, resulting in a high V_OC. Further, the base thickness of InGaAs solar cells was optimized to enhance J_SC. Subsequently, we fabricated two InGaAs/InGaAsP dual-junction solar cells comprising an InGaAs bottom cell with either a front or rear heterojunction (2J-FHJ or 2J-RHJ) structure and compared their performances. The 2J-FHJ device demonstrated a superior efficiency (7.39%) compared to 2J-RHJ (7.37%). The theoretical calculation results reveal that the 2J-FHJ structure holds great potential for achieving a higher efficiency, approximately 42.6%, in four-junction solar cell applications under non-concentrated illumination.