Design Optimization of CdTe/Si Tandem Solar Cell using Different Transparent Conducting Oxides as Interconnecting Layers

Abstract Due to the efficiency limit placed by Shockley-Queisser for the single junction solar cells, interest has now shifted to the design and fabrication of cost-effective and more efficient multijunction or tandem solar cells. In this study, wxAMPS 3.0 numerical simulation software has been used in designing and optimizing a CdTe/Si based tandem solar cell structure utilizing some selected transparent conducting oxides (TCOs) as electrical and optical interconnectors. Among the three TCOs (SnO2, ITO and AZO) used here, AZO at a thickness of 20 nm illustrated the best efficiency of 26.7156% with Voc = 2.1261 V, Jsc = 13.8071 mA/cm2 and FF = 0.9100 when the thickness of CdTe and Si layers were fixed at 1 µm and 300 µm, respectively. The best possible efficiency for the design was obtained at 38.0417% by reducing the p-CdTe layer thickness from 1 µm to 0.2 µm. This shows that, with proper design and optimized fabrication process, CdTe/Si tandem can push the efficiency beyond the existing single junction limit.