Effect of an upward and downward interface dipole langmuir-blodgett monolayer on pentacene organic field-effect transistors: A comparison study

We studied carrier behaviors of pentacene organic field-effect transistors (OFETs) with an upward and a downward orientation dipole monolayer, inserted between the organic active layer and gate insulator by the Langmuir-Blodgett technique. The OFETs with an upward orientation of dipole monolayer showed large negative threshold voltage and high contact resistance compared with the reference OFETs without dipole monolayer, while the OFETs with a downward orientation dipole monolayer exhibited positive threshold voltage and low contact resistance. Based on the findings from this comparison study, we argued that using interface dipole monolayer is a useful way to design OFET performance.