“…In this contribution, we present direct transport measurements of deliberately synthesized perylene tetracarboxylic diimide (PTCDI) derivatives bridged across two electrodes in an electrochemical environment. PTCDI and its derivatives are attractive for molecular electronics as they represent a model redox system. ,, Tao et al determined the conductance of PTCDIs at single-molecule level using scanning tunnelling microscopy (STM) break junction techniques and detected large electrochemical gating effect . The Wandlowski group has investigated electrochemical and charge transport properties of symmetrical and unsymmetrical PTCDI derivatives using spectro-electrochemical and electrochemical STM break junction techniques. , Though the concept of electrochemical (electrolyte) gating effect on the charge transport in molecules was initiated by White, Wrighton, and co-workers, electrolyte gating of single organic molecule was experimentally achieved by Haiss et al and by Tao, and further developed by other groups using STM and/or STM break junction techniques. ,,− In an electrochemical electrolyte solution, charge transport can be regulated by external perturbation (electrode potential), so-called electrochemical gating. ,, In an STM break junction configuration, the potentials of STM tip and substrate electrodes, acting as the “source” and the “drain” electrodes, are independently controlled by a bipotentiostat using a reference electrode, i.e., the “gating electrode” (Figure A).…”