NUMERICAL MODELING OF ZnxCd1-xS/ZnxCd1-xTe SOLAR CELLS BY AMPS-1D

Abstract

Cadmium Telluride (CdTe) thin film solar cell has long
been recognized as a leading photovoltaic candidate for
its high efficiency and low cost. The efficiency of CdTe
based solar cell can be increased using ternary material
as window and absorber layer. In this study a new solar
cell structure was proposed, where Zinc Cadmium
Sulfide (ZnxCd1-xS) was used as window layer and Zinc
Cadmium Telluride (ZxCd1-xTe) was used as an absorber
layer with an added advantage of variable band gap. By
varying the composition of the zinc content, the band
gap was varied between 2.42-3.7eV for ZnCdS and
1.45-2.25eV for ZnCdTe respectively, thereby
increasing the cell’s performance in the lower
wavelength region, resulting in higher efficiency. In this
work the band gap of ZnxCdx-1Te layer is used 1.53eV
which is in the optimum range, can be achieved with Zn
composition of 0.09. Incorporation of Zn can be reduced
the window and absorber layer thickness significantly,
which eventually will reduce the material cost, save
processing time and energy required for fabrication. The
numerical simulation has been performed using AMPS-
1D simulator to explore the possibility of higher
efficiency and stable ultra thin ZnCdS/ZnCdTe cell with
suitable Back Surface Field (BSF). The performance
parameters were found better in the modified cell
structure. The effect of BSF layer and the operating
temperature on the cell performance parameters was
also investigated in this work. The cell structure of
Glass/ZnO/Zn2SnO4/ZnCdS/ZnCdTe/ZnTe/Ni showed
highest conversion efficiency of 21.17% than other cells
with different BSF. The cell with Cu2Te BSF showed
better stability with TC of - 0.15%/°C in the operating
temperature range from 25˚C to 40˚C. After 40˚C
temperature the cell with Cu2Te/Mo gives better
stability as its efficiency remains almost unchanged in
the operating temperature up to 100˚C with a TC
0.01%/˚C.