Design and simulation of high efficiency AlxGa1−xAs/Ga0.47 in0.53asyP1−y bandgraded 2-J tandem solar cell

The III-V compound semiconductor based multi-junction tandem solar cell has ultra-high efficiency and better cell stability. In this paper, a new type of AlGaAs/GaInAsP 2-J tandem solar cell has been introduced and designed by bandgrading thereby obtaining a set of descending layers having bandgap from 2.09eV-0.84eV and grown over a Ge substrate. For matching the currents between subcells, a tunnel junction has been used as an interconnection between the two subcells. Moreover, the used materials and the characteristics of the designed cell have been discussed in the paper. After that, short circuit current, open circuit voltage, fill factor and cell efficiency have been simulated for proposed AlGaAs/GaInAsP 2-J cell under AM1.5 spectrum which have proved it as highly efficient as previously researched 3-J cell. Finally, following the newly designed AlGaAs/GaInAsP 2-J tandem solar cell, design of AlGaAs/GaInAsP/GaAsSb 3-J tandem solar cell and AlGaAs/GaInAsP/GaAsSb/GaInAs 4-J tandem solar cell design have also been introduced and proposed.