Interplay between barrier contact, mobility models, and traps in the electrical characteristics of OTFT

Abstract

We have investigated the electrical properties of organic thin-film transistor by using two-dimensional drift-diffusion simulations. The dependence of electrical haracteristics on the mobility model and on the barrier height of the contacts is carried out. We found that the field dependence of the carrier mobility is responsible for non-linearity of the drain current. This non-linear behavior is mainly related to the field-dependence of the mobility and to the barrier height of the contacts. The simulation allow us to clear understand the differences in the mobility derived by the analysis of I-V curve (as done experimentally by using standard MOSFET theory) and the intrinsic mobility of the organic layer. The effects of the interface traps has also be considered. The dependence of the threshold voltage on the density, energy level and model of the traps has been outlined. Results of the simulations have been compared with experimental data. The comparison between experimental data and simulation allow us to clearly identify the physical mechanism responsible for the measured characteristics. Finally we also consider the effect of the device bending on the electrical characteristic of all-plastic OTFT.