This study investigates the device performance of hydrogenated amorphous silicon-carbon (a-SiC:H)/microcrystalline-silicon (mu c-Si)/hydrogenated amorphous silicon-germanium (a-SiGe:H) PIN thin film solar cells using Technology Computer Aided Design (TCAD) simulations. The physical parameters used in the TCAD simulations are calibrated to reproduce experimental data. The influence of the density of states (DOS) and intrinsic layer (I-layer) thickness on the performance of thin film solar cells is investigated. According to the simulation results, the highest efficiency is approximately 9% when the I-layer thickness is 4 mu m. (C) 2009 Elsevier B.V. All rights reserved.