Numerical Modeling to Improve the Efficiency of Cadmium Sulfide/Copper Indium Sulfide (CdS/CuInS2) Thin Film-Based Solar Cells
Abstract
In this study, CIS-based devices were simulated and studied their performance by SCAPS (Solar Cell Capacitance Simulator) software. SCAPS is 1-dimensional graphic solar cell simulation software that estimates quantum efficiency, current-voltage characteristics, energy bands, and spectral response by solving Poisson's equations and continuity equations for electrons and holes. The solar cell structure was designed with CdS as an n-layer and CuInS2 as a p-layer for the first simulation and with ZnO as a window layer, CdS as a buffer layer, and with CuInS2 absorber layer for the next simulation. The CuInS2 layer thickness was changed from 0.5 to 2 µm, with other layer thicknesses kept constant, viz. 0.5 µm thickness for the CdS layer, which increased the solar cell efficiency from 5.6 to 8.47%. The optimized thickness of CuInS2 obtained was 2 µm. The thickness of ZnO varied from 0.15 to 1 µm, and the rest of the layer thicknesses were kept constant, viz. 2 µm for CuInS2, and 0.5 µm for CdS. An optimized 0.8 µm thickness of ZnO has been obtained with 12.74 % efficiency. The shallow uniform densities for the CuInS2 layer and ZnO layer were optimized to 1 x 1018 (1/cm3) and 1 x 1015 (1/cm3).