A new analytical DC model accounting for the kink effect of polycrystalline silicon thin-film transistors (poly-Si TFTs) is presented in this paper. When considering the exponential density of trap states in the film, a quasi-two-dimensional approach is used to give an analytic expression for avalanche multiplication factor. Compared with the available experimental data, the proposed model provides accurate description of the output characteristics over a wide range of bias voltages. Based on the kink model, higher drain voltages or higher trap states density leads to higher avalanche multiplication factors. (C) 2009 Elsevier Ltd. All rights reserved.