Substituent-Controlled Reversible Switching of Charge-Injection-Barrier   Heights at Metal/Organic-Semiconductor Contacts Modified with Disordered   Molecular Monolayers
  Electrically stimulated switching of a charge injection barrier at the interface between an organic semiconductor and an electrode modified with a disordered monolayer (DM) is studied by using various benzenethiol derivatives as DM molecules. The switching behavior is induced by a structural change in the DM molecules, and is manifested as a reversible inversion of the polarity of DM-modified Au electrode/rubrene/DM-modified Au electrode diodes. The switching direction is found to be dominantly determined by the push-back effect of the thiol bonding group, while the terminal group modulates the switching strength. A device with 1,2-benzenedithiol DMs exhibited the highest switching ratios of 20, 100, and 1000 for the switching voltages of 3, 5, and 7 V, respectively. A variation in the tilt angle of benzenethiol DMs owing to the application of 7 V is estimated to be smaller than 23.6 degrees by model calculations. This study offers an understanding for obtaining highly stable operations of organic electronic devices, especially with molecular modification layers. 
Ryo Nouchi and Takaaki Tanimoto
cond-mat.mtrl-sci