The Control of Intramolecular Through-Bond and Through-Space Coupling in Single-Molecule Junctions

Abstract

Electronic coupling between individual building blocks plays an essential role in charge transport through molecular materials and devices. However, the investigation of the transmission mechanism in charge transport via intramolecular coupling remains challenging. Herein, we demonstrate the transition of the intramolecular through-bond and through-space coupling in a single-molecule junction with a family of diketopyrrolopyrrole (DPP) derivative by varying intramolecular donor-acceptor (D-A) interactions. The transition is accomplished by regulating D-A interactions by inserting different aromatic rings inside, leading to two orders of magnitude difference of the single-molecule conductance. The flicker noise analysis demonstrates that the conductance difference arises from the control of the contribution between through-bond and through-space coupling. These findings are further supported by the calculation that the intramolecular coupling among molecular building blocks correlates with the D-A interaction, providing a promising way to regulate the contribution between through-bond and through-space coupling in the charge transport through molecular materials and devices.