Embedded-dipole self-assembled monolayers tune contact resistances in p‐type and n‐type organic transistors
Highly conductive interfacial layers are designed, which allow tuning the contact resistance of organic thin‐film transistors over three orders of magnitude with minimum values well below 1 kΩ cm. This not only permits the realization of highly competitive p‐type (pentacene‐based) devices on rigid as well as flexible substrates, but also enables the realization of n‐type (C60‐based) transistors with comparable characteristics utilizing the same electrode material (Au). The contact resistances are reduced by i) eliminating the injection barrier through a suitable dipole orientation, and by ii) boosting the transmission of charge carriers through a deliberate reduction of the SAM thickness. Notably, the embedding of the dipolar group into the backbones of the SAM‐forming molecules allows exploiting their beneficial effects without modifying the growth of the active layer.
This work is a collaboration between the Institute of Solid State Physics, TU Graz, the Stadlober group at the Materials Institute, Joanneum Research, Weiz (Austria), the Zharnikov group at the University of Heidelberg (Germany), and the Terfort group at the Goethe University Frankfurt/Main (Germany).