The impact of junction position and type on the performance of InGaAs solar cells for multijunction applications

Abstract 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 an InGaAs subcell for high-efficiency multijunction solar cells. The key findings include the following: a front-junction configuration enables efficient carrier collection, resulting in a high <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>J</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="italic">SC</mml:mi> </mml:mrow> </mml:msub> </mml:math> ; and heterojunctions and a rear-junction configuration contribute to suppressing Shockley–Read–Hall recombination, resulting in a high <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>V</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="italic">OC</mml:mi> </mml:mrow> </mml:msub> </mml:math> . Further, the base thickness of InGaAs solar cells was optimized to enhance <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>J</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="italic">SC</mml:mi> </mml:mrow> </mml:msub> </mml:math> . Subsequently, we fabricated two InGaAs/InGaAsP dual-junction (2J) solar cells comprising an InGaAs bottom cell with either a front heterojunction (FHJ) or rear heterojunction (RHJ) structure and compared their performances. The 2J-FHJ device demonstrated a superior efficiency (7.39%) compared to the 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 nonconcentrated illumination.