The band bending at the transparent conductive oxides/hydrogenated p-doped amorphous silicon (p-a-Si:H) interface is one of the most important factors limiting the performances of HIT (Heterojunctions with Intrinsic Thin layers) solar cells. In order to study this effect, a solar cell (Indium Tin Oxide (ITO)/p-a-Si:H/i-polymorphous Si:H/n-doped crystalline silicon (n-c-Si)) simulation, focused on the front contact barrier height, has been performed. The results show that a reduction of the surface potential barrier at the interface ITO/p-layer leads to an increase of the built-in potential, and hence an increase of open circuit voltage and fill factor. We have also observed that the performance of HIT solar cells remains constant above 12nm thickness of the p-layer. (C) 2008 Elsevier B.V. All rights reserved.