CIGS growth on a GaP/Si(001) platform : towards CIGS/Si tandem solar cells

We propose to explore tandem junctions associating single crystalline silicon bottom cell (Eg = 1.12 eV) and wide bandgap (1.7 eV) CIGS top cell, using GaP intermediate layer. Our purpose is to grow CIGS films under epitaxial conditions on GaP to improve the top cell efficiency, thanks to a reduction of the structural defects density detrimental for the cell performance, so that CIGS-Si tandem cells can emerge as cost competitive for the next generation of PV modules. Epitaxy of CIGS (CIGSe or CIGSu) on GaP/Si platform is demonstrated and preliminary results on AZO/ZnMgO/CdS/CIGS cells on Mo/Glass and GaP/Si are reported.