Polycrystalline Si (poly-Si) thin films with large grain size have been deposited by nucleation control with intermittent source gas supply using atmospheric pressure chemical vapor deposition. The grain size can be controlled in the range From 3.1 to 31 mu m. The Hall mobility of poly-Si thin films increased to 69.9 cm(2)/V s for a grain size of 15 mu m after hydrogenation treatment, The grain boundaries in this film have a weak influence on the majority carrier transport due to effectively passivated grain boundaries and larger grain size. The photovoltaic performance of poly-Si thin film solar cells. especially the open circuit voltage, was also improved with the increase of the grain size, (C) 2005 Elsevier B.V. All rights reserved.