Two-Terminal III-V//Si Triple-Junction Solar Cells with Power Conversion Efficiency of 35.9 % at AM1.5g

III-V//Si multi-junction solar cells offer a pathway to increase the power conversion efficiency beyond the fundamental Auger limit of silicon single-junctions. In this work we demonstrate how the efficiency of a twoterminal wafer-bonded III-V//Si triple-junction solar cell is increased from 34.1 % to 35.9 % under an AM1.5g spectrum, the highest reported efficiency for silicon based multi-junction solar cell technologies. This improvement was accomplished by two main factors. First, the integration of a GaInAsP absorber in the middle cell increased the open-circuit voltage by 51 mV. Second, a better current matching of all subcells enhanced the short-circuit current by 0.7 mA/cm².