An analytical model based on hydrogenated amorphous silicon thin film transistors (a-Si:H TFTs) is proposed to interpret the degradation of output characteristics at different temperatures. The Poisson equation and Gauss theorem are applied to model the temperature effect on the total density of defect states. And the expression of the drain current is derived by exploiting the nonuniform distribution of surface potential. It indicates that the total density of defect states varies linearly with the temperature, whereas the drain current shows an exponential increase with the temperature. In addition, the influence of temperature on the effective mobility under different electric fields is also taken into consideration and results fit well with the experimental data. (C) 2012 Elsevier Ltd. All rights reserved.