A new analytical threshold voltage model for the doped polysilicon thin-film transistors (poly-Si TFTs) is proposed in this paper, which is related to U-shaped distribution of density of states in the grain boundary, the gate oxide thickness. the substrate doping concentration, and the grain size. Moreover, the new model has a simple functional form and it can reduce to the threshold voltage model of the conventional long channel MOSFET when the grain size is large. (C) 2009 Elsevier Ltd. All rights reserved.