Proposal of a GaP/Si 4-terminal Tandem Solar Cell

We propose a GaP/Si 4-terminal tandem solar cell. It is shown that its theoretical limit efficiency exceeds 40% under ideal conditions. The use of ZnS as a window layer for the top GaP cell is also proposed, and its suitability is shown from the perspective of band alignment. Furthermore, to resolve the lattice mismatch and adjust the conduction band offset at the interface between window layer and GaP, we also proposed using Zn(Cd,Mg)S, which is lattice-matched to GaP.