Projects per year
Quantum dots (QD) with electric-field-controlled charge state are promising for electronics applications, e.g., digital information storage, single-electron transistors, and quantum computing. Inorganic QDs consisting of semiconductor nanostructures or heterostructures often offer limited control on size and composition distribution as well as low potential for scalability and/or nanoscale miniaturization. Owing to their tunability and self-assembly capability, using organic molecules as building nanounits can allow for bottom-up synthesis of two-dimensional (2D) nanoarrays of QDs. However, 2D molecular self-assembly protocols are often applicable on metals surfaces, where electronic hybridization and Fermi level pinning can hinder electric-field control of the QD charge state. Here, we demonstrate the synthesis of a single-component self-assembled 2D array of molecules [9,10-dicyanoanthracene (DCA)] that exhibit electric-field-controlled spatially periodic charging on a noble metal surface, Ag(111). The charge state of DCA can be altered (between neutral and negative), depending on its adsorption site, by the local electric field induced by a scanning tunneling microscope tip. Limited metal-molecule interactions result in an effective tunneling barrier between DCA and Ag(111) that enables electric-field-induced electron population of the lowest unoccupied molecular orbital (LUMO) and, hence, charging of the molecule. Subtle site-dependent variation of the molecular adsorption height translates into a significant spatial modulation of the molecular polarizability, dielectric constant, and LUMO energy level alignment, giving rise to a spatially dependent effective molecule-surface tunneling barrier and likelihood of charging. This work offers potential for high-density 2D self-assembled nanoarrays of identical QDs whose charge states can be addressed individually with an electric field.
- density functional theory
- double-barrier tunneling junction
- low-dimensional nanostructures
- noncontact atomic force microscopy
- organic quantum dots
- scanning tunneling microscopy and spectroscopy
- supramolecular self-assembly
- 1 Active
Fuhrer, M., Bao, Q., Culcer, D., Davis, M., Davis, J. A., Hamilton, A., Helmerson, K., Kalantar-Zadeh, K., Klochan, O., Medhekar, N., Ostrovskaya, E., Parish, M., Schiffrin, A., Seidel, J., Sushkov, O., Valanoor, N., Vale, C., Wang, X., Wang, L., Galitskiy, V., Gurarie, V., Hannon, J., Höfling, S., Hone, J., Rule, K. C., Krausz, F., Littlewood, P., MacDonald, A., Neto, A., Oezyilmaz, B., Paglione, J., Phillips, W., Refael, G., Spielman, I., Tadich, A., Xue, Q., Cole, J., Perali, A., Neilson, D., Lin, H., Sek, G., Gaston, N., Hodgkiss, J. M., Tang, M., Karel, J., Nguyen, T. & Adam, S.
Australian Research Council (ARC), Monash University – Internal School Contribution, Monash University – Internal Department Contribution, Monash University – Internal Faculty Contribution, Monash University – Internal University Contribution, University of Wollongong, University of Queensland , Tsinghua University, University of New South Wales, Australian National University , RMIT University, Swinburne University of Technology
29/06/17 → 28/06/24