The effects of hot carriers on the electrical characteristics of polycrystalline silicon p-channel thin film transistors have been analyzed, combining experimental data and numerical simulations. The transfer characteristics showed minor variations upon application of prolonged bias stress, while the output characteristics presented a reduction of kink effect. These results have been explained by using a self-consistent model based on the trapping of injected hot electrons. The authors’ charge injection model provided a precise evaluation of the extension of the trapped charge regions, at both front and back interfaces. By using such trapped charge distributions, it was possible to reproduce the output characteristics variations as well as the minor on-current increase observed in the transfer characteristics after bias stress.