Manipulating the optimal transport orbital and virtual states in a supramolecular transistor

Abstract

Supramolecular electronics bridges the gap between single-molecule electronics and bulk, plastic electronics, and is embodied as one of the biggest promises of nanometer electronics made by supramolecular functional materials. Within this field, the way in which electrons propagate through the supramolecule plays a profound role both in designing supramolecular devices and in understanding the structure–property relationships at the molecular level. Herein, we consider a supramolecular transistor, which contains bipartite molecular monomers, with one molecular orbital is non-interacting, whereas the other one is strongly correlated. Modeling this device using the two-impurity Anderson model, we unravel the orbital selections and the virtual states in the electronic transport process with the aid of the celebrated numerical renormalization group method. We demonstrate that if both orbitals are in their particle-hole symmetric regimes, electrons favor to transmit through the non-interacting molecular orbital via the resonant tunneling process, rather than through the strongly correlated molecular orbital via the Kondo effect, despite the energy of the strongly correlated orbital is lower. This phenomenon indicates that if the Kondo effect occurs, it experiences a temporarily doubly occupied virtual state. Interestingly, the situation reverses if the inter-molecule hopping integral is applied, where the strongly correlated orbital becomes optimal and the virtual state turns to be an empty state. To understand these behaviors, both the static and the dynamical properties, as well as those thermodynamic quantities are studied in detail, and necessary physical arguments are given. Our findings afford deep insights into the manipulations of the optimal transport orbital and the Kondo behaviors within quantum impurity devices.