Numerical modeling of copper indium disulfide thin film based solar cells

Abstract

In this work we have modeled CuInS 2 based solar cells. CuInS 2 is a p-type semiconductor which is used as an absorber layer in the heterojunction thin film solar cell ZnO:Al/i-ZnO/CdS/CuInS 2 /Mo. Numerical modeling was done by SCAPS-1D. The simulation focuses on studying several effects on photovoltaic parameters; open circuit voltage, density of short circuit, fill factor and efficiency. In a first step we have studied temperature effect; the performance of the cell decreased because of the decrease of open circuit voltage due to the rise of reverse current, in the other hand the fill factor increases at high temperature which is the same behavior of Silicon based solar cells. Thickness of the absorber layer has been varied too, 2.5 μm of thickness is the optimum value chosen instead of higher thickness in order to have a compromise between cost and efficiency. After that we decided to design a Cadmium free cell by replacing Cadmium Sulfide (CdS) layer with Tin Disulfide (SnS 2 ). However, cadmium layer showed better efficiency than SnS 2 . Then we discussed the importance of back surface field layer (Cu 2 O), whom insertion leads to improve the efficiency to 22.73% compared to the efficiency obtained by the conventional structure 12.64%. • New structures ZnO:Al/i-ZnO/CdS/CuInS 2 /Cu 2 O/Mo and ZnO:Al/i-ZnO/SnS 2 /CuInS 2 /Cu 2 O/Mo have been modeled. • The ZnO:Al/i-ZnO/CdS/CuInS 2 /Cu 2 O/Mo showed a good stability under temperature varied from 300 K to 325 K. • An efficiency of 22.73% have been achieved with ZnO:Al/i-ZnO/CdS/CuInS 2 /Cu 2 O/Mo. • The Cadmium free structure ZnO:Al/i-ZnO/SnS 2 /CuInS 2 /Cu 2 O/Mo showed an efficiency of 21.62%.