Modelling and Analysis of Multi-Junction Photovoltaic Cells

This study involves the design and modelling of a triple junction lattice-matched photovoltaic cell using AlGaAs, GaAs and Germanium. Its performance is modelled using MATLAB under AM1.5G spectral irradiance. Multi-junction photovoltaic cells can absorb photons from multiple sections of the irradiation spectrum, however, the mismatch in the lattice constants of the substrates makes it prone to stacking faults which reduce its efficiency. The proposed design uses substrates with a lattice mismatch of less than 0.1% to minimize this issue. The performance of a silicon photovoltaic cell is modelled under the same conditions and used as a benchmark. At 300K, the efficiency of the silicon photovoltaic cell was 14.56%, whereas the efficiency of the proposed multi-junction photovoltaic cell was found to be 43.32%. To compare the photovoltaic cells, the analysis also evaluates the effect of material thickness, doping and heating on parameters such as fill factor, and efficiency.