Functionalized tetrapodal diazatriptycenes for electrostatic dipole engineering in n-type organic thin film transistors

Abstract

A diazatriptycene‐based tetrapodal scaffold with thiol anchors enforces a nearly upright orientation of functional groups, introduced to its quinoxaline subunit, with respect to the substrate upon formation of self‐assembled monolayers (SAMs). Substitution with electron‐withdrawing fluorine and cyano as well as electron‐rich dimethylamino substituents allows tuning of the molecular dipole and, consequently, of the work function of gold over a range of 1.0 eV (from 3.9 to 4.9 eV). The properties of the SAMs are comprehensively investigated by infrared reflection absorption spectroscopy, near edge X‐ray absorption fine structure spectroscopy, and X‐ray photoelectron spectroscopy. As prototypical examples for the high potential of the presented SAMs in devices, organic thin‐film transistors are fabricated.