Invited talk

Simulation of single electron molecular transistors

Kurt Stokbro¹ and James Avery²

¹QuantumWise A/S, Fruebjergvej 3, 2100 Copenhagen, Denmark

²Copenhagen University, Denmark

In this presentation we present simulations with the Atomistix ToolKit of a molecule weakly coupled with metallic electrodes [2]. The device is operating in the incoherent regime, i.e. a single electron molecular transistor. The theoretical methodology of the simulation is illustrated for a benzene and C₆₀ molecular transistor [2]. The main objective is the simulation of a single OPV5-tBu molecule between gold electrodes. This system was previously experimentally investigated by Kubatkin et al. [1]. In order to directly simulate the experimental geometry we have developed a finite-element DFT method that allows efficient treatment of complex molecules interacting with arbitrarily large electrostatic environments [3]. The details of the implementation will be discussed. The simulations are compared with experimental data of Kubatkin et al. [1]. We find quite different properties than in the experiment and point to a number of possible reasons for the discrepancy.

Figure 1: (top) OPV5 transistor setup. (bottom) The simulation setup with the finite element mesh. The mesh is fine around the molecule and coarse away from the molecule.

[1] S. Kubatkin et al., Nature 425, 698 (2003).

[2] K. Stokbro, Journal of Physical Chemistry C 114, 20461–20465 (2010).

[3] J. Avery, PhD Thesis, Copenhagen University (2011).