Le Professeur Colin Van Dick, du département de Chimie, de l'Universite de Alberta, Edmonton, Canada, donnera un séminaire le vendredi 5 juillet à 10h, en salle 774 (Bât. Lavoisier, 15 rue Jean-Antoine de Baïf, 75013, Paris)
autour de la "thématique jonction moléculaire"
Molecular junctions are new nanomaterials made of one molecule, or a thin organic layer, sandwiched between two metallic electrodes. These systems are now widely and intensively characterized because of their potential applications in nanoelectronics. Ideally, molecular electronics aim at controlling and designing the current-voltage characteristics of junctions, by using different molecular structures. However, this has been challenging for several reasons. In this presentation, I will address two of those. First, it has been difficult to modify the band alignment of molecular levels in a molecular junction. I will discuss the band diagram of a molecular junction and show how the creation of dipoles in the device leads to large built-in fields. If those are not properly taken into account, built-in fields can lead to a lack of control in the design of device characteristics. Second, it has been difficult to characterize the charge transport mechanism appearing in junctions thicker than 6 nm. I will propose that beyond the coherent tunnelling regime, the charge transport becomes limited and driven by the injection of carriers at the metal-molecule interface. I will propose a simple model and compare to experimental data. Overall, this presentation will stress the major role played by the interfaces in nanometric molecular devices.
Van Dyck, C., & Ratner, M. A. (2015). Molecular rectifiers: a new design based on asymmetric anchoring moieties. Nano letters, 15(3), 1577-1584.
Meng, F., Hervault, Y. M., Norel, L., Costuas, K., Van Dyck, C., Geskin, V., ... & Chen, X. (2012). Photo-modulable molecular transport junctions based on organometallic molecular wires. Chemical Science, 3(10), 3113-3118.
Van Dyck, C., & Bergren, A. J. (2018). Large Built‐In Fields Control the Electronic Properties of Nanoscale Molecular Devices with Dipolar Structures. Advanced Electronic Materials, 4(5), 1700656.