Bias-stress induced contact and channel degradation in staggered and coplanar organic field-effect transistors

We have investigated the dependence of bias-stress induced degradation in organic field-effect transistors on the device configuration. We show that separation of contact and channel effects is essential for understanding bias-stress instabilities. In coplanar device configurations, an increase in source contact resistance during current flow is primarily responsible for a rapid device degradation. In contrast, in staggered device configurations, the significantly slower reduction in current is primarily due to charge trapping in the channel leading to an increase in threshold voltage, while the contacts themselves do not exhibit significant degradation. (c) 2008 American Institute of Physics.