Device Structures for High-Efficiency Chalcopyrite Tandem Solar Cells

29th European Photovoltaic Solar Energy Conference and Exhibition; 1722-1724
In order to obtain more efficient chalcopyrite solar cells, we have considered an adequate tandem structure. We have calculated bandgap dependence of the cell efficiency of top cells and bottom cells with series and parallel connection. Our calculations have revealed that parallel connection is superior to series connection. With some assumptions concerning absorption, we calculate maximum efficiencies of the tandem cells to be in the range of 22 to 24% with the 20%-efficiency CIGS as bottom cells. To increase efficiency of the tandem cells, in addition to increasing conversion efficiency of CIGS bottom cells, we should focus on wide-bandgap chalcopyrite top cells.