Design and Fabrication of CdTe//Si Four-Terminal Mechanical Stacked Solar Cell

As single-junction devices are becoming increasingly difficult to achieve higher efficiencies, a great amount of design and fabrication of multijunction solar cells has been reported. There have been many independent studies on silicon and II-VI photovoltaic materials, but their integration to form II-VI/crystalline silicon tandem solar cell is still relatively rare. In this work, the structure of cadmium telluride (CdTe)//Si(TOPCon) four-terminal (4-T) mechanical stacked solar cell was numerically simulated and the performances of this cell were explored by varying the thickness of CdTe absorber layer in the top cells. The simulation results demonstrated that the 32.2% optimum efficiency of CdTe//Si(TOPCon) 4-T mechanical stacked solar cell can be obtained when the CdTe thickness was about 600 nm. Specifically, tungsten doped indium oxide (IWO) as a transparent back electrode was innovatively incorporated into the top cell to increase the transmission in the near-infrared region (800–1200 nm), which can reach the bottom cell well and be absorbed. Finally, glass/SnO₂:F/CdS/CdTe/CuCl₂/IWO translucent solar cell as a top cell was prepared, and then, CdTe//Si(TOPCon) 4-T mechanical stacked solar cell with a 12.4% conversion efficiency were fabricated for the first time with rigorous and meticulous optical balance design.