Abstract:
In this research, the performance variation of a newly modeled tandem device was investigated. A
thin-film photovoltaic tandem device was created with a CdS/CdTe top cell configuration and a thick
Si bottom cell configuration. The goal of this numerical simulation study was to enhance the
performance of the tandem photovoltaic device. Therefore several modifications and optimizations
were done to the device structure. An Mg-doped ZnO-based (MZO) layer was used as a High
Resistance Transparent (HRT) layer with a very thin CdS layer. The thickness of the CdS was reduced
to minimize its parasitic absorption property. The top and the bottom cell models were developed by
using a special script introduced in SCAPS-1D solar cell capacitance simulator software. An artificial
surface defect layer (SDL) was introduced between the window and the absorber of the top cell. The
optimization procedure was carried out by altering the thicknesses of the top and the bottom
absorbers and also varying the defect concentrations of the CdS/SDL interface and SDL/CdTe
interface. The current matching condition of the tandem device and the device performance under the
AM1.5G spectrum were also investigated. As the outcomes, we have identified the minimum possible
defect density concentrations required for the window to absorber interfaces of the top cell to achieve
the optimum performance. The experimental research work is suggested to further confirm the
modeling results of the tandem device structure.
