A new analytical surface-potential-based drain current model is presented for the organic thin-film transistors (TFTs) when carriers are confined in two dimensions. Following the carrier multiple trapping and release (MTR) conduction theory, i.e., the assumption that the trapped carrier concentration is much higher than the free carrier concentration, the model is developed. The presented model can account for the linear regime and saturation regime by a single formulation. The calculated results of the presented model are verified by the avail...