Effects of ZnS Buffer Layer on Performance of CIGS Solar Cell

Abstract

Cu(In,Ga)Se2 (CIGS)-based thin-film solar cells are currently among the most efficient. Zinc sulfide (ZnS) is the best buffer layer used in CIGS-based solar cells because it is non-toxic and has a wide band gap. In this study, we present a simulation of a CIGS solar cell with a ZnS buffer layer, carried out using the Silvaco-Atlas simulator. We attained an efficiency of 24.13%, short-circuit current of 37.81 mA/cm2, an open circuit voltage of 740 mV and a fill factor of 78.78% at a bandgap around 1.41 eV, corresponding to an x ratio of 0.5. The photovoltaic performance of the ZnS/CIGS solar cell is improved by optimizing the effects of layer parameters such as thickness, acceptor and donor densities of the CIGS absorber and ZnS buffer layers. For a 0.035 μm thick ZnS acceptor with a density of 6 × 1017 cm-3 and a 3 μm thick CIGS donor with a density of 1018 cm-3, a maximum efficiency improved to 27.22%.

Keywords

• buffer layer (zns)
• cigs
• solar cell
• optimization
• silvaco-atlas