Bias stress and condensation of mobile trap agents in printed organic transistors

We report the relationship between the device instability and the presence of hydrophilic/hydrophobic boundary that is conventionally utilized to obtain well-defined film patterning in printed electronics devices. Pentacene thin-film transistors composed of inkjet-printed synthetic-metal electrodes exhibit notable bias stress effects whose appearance and disappearance depend critically on the positioning of the hydrophilic/hydrophobic boundary within the channel. The Kelvin probe force microscopy measurements revealed that the bias-stress effect is originated in the temporal evolution of trapped charge densities accumulated at the hydrophilic/hydrophobic boundary, in which the mobile nature of trap agents on the hydrophilic surface take crucial role.