Design and Modeling of Metamorphic Dual-Junction InGaP/GaAs Solar Cells on Si Substrate for Concentrated Photovoltaic Application

We have investigated the concentrated photovoltaic performance of metamorphic monolithic InGaP/GaAs dual-junction (2-J) solar cells on Si substrate under AM1.5d spectrum using finite-element analysis. The current-matching condition between each subcell was realized for threading dislocation density varying from 10⁵ to 10⁷ cm ^-2, emanating from the mismatch between GaAs and Si substrate. Through comprehensive cell design and by mitigating the losses due to shadowing effect and series resistance, we present an optimal cell design for harnessing the maximum potential of 2-J InGaP/GaAs cell integrated on Si substrate for concentrated photovoltaics. The optimization of front grid spacing and sheet resistance of the window layer were the key design parameters taken into consideration for extending the peak performance toward higher concentrations. Finally, we present an optimized 2-J InGaP/GaAs cell design on Si, which exhibited a theoretical conversion efficiency of 33.11% at 600 suns at a realistic TDD of 10⁶ cm^-2, indicating a promising future for integrating III-V cell technology on Si for low-cost concentrated photovoltaics.