Simulation and modeling of a multi-junction solar cell with novel concentration

Si-Ge is the best material for the bottom layer of this new three-junction high-efficiency solar cell. As a proof of concept, the top and middle subcells contain high-quality bandgap 1.9 eV GaInP2 and 1.42 eV GaAs materials, while the bottom subcell features a novel semiconductor material with a bandgap of 0.838 eV, Si0.38Ge0.62. Optical transparency and current conductivity are enhanced by the lattice matching (5.66) of the materials used in this design. Standard solar cell equations of the modified spectral p-n junction model and in-house MATLAB code were used to calculate the short circuit current density (Jsc), reverse saturation current density (J0), the open-circuit voltage (Voc), the maximum power point, the fill factor (FF), and the photoconversion efficiency () for the proposed multijunction solar cell (MJSC). The quantitative study was performed using the ASTM G173-03 reference spectra at an airmass irradiance of AM1.5G globally. Simulations have shown that the GaInP2/GaAs/Si0.38Ge0.62 solar cell's conversion efficiency at AM1.5G is 47.1% under a single sun's normal illumination and 56.4% with solar illumination of one thousand suns.

• Supervision