In this paper CuInS2 solar cells have been numerically simulated based on a one-dimensional device physics simulator: Analysis of Microelectronic and Photonic Structures. Solar cells having a typical structure Al/ZnO:Al/n-CdS/p-CuInS2/Mo have been modeled. Various factors that affect cell performance have been studied, such as thickness and bandgap of the CuInS2 absorber layer, and thickness of the CdS buffer layer. The photovoltaic parameters are determined from the current density-voltage curves. The solar spectral response and recombination mechanism of the cells are represented by quantum efficiency-lambda curves and net recombination rate-position curves, respectively. In this study, a simulated efficiency of 20.4% has been obtained with open-circuit voltage of 0.94V, short-circuit current density of 26.2mA/cm(2) and fill factor of 0.84 for the CuInS2 solar cell with a bandgap of 1.40 eV. It is found that optimal thicknesses of the CuInS2 absorber layer and the CdS buffer layer are around 2000 and 50 nm, respectively, while optimal bandgap of the CuInS2 absorber layer is 1.40 eV. (C) 2013 Elsevier B. V. All rights reserved.