Towards on-surface polymerization of dibromo-benzothiadiazole

Abstract

The electronic structure and highly efficient electron transport performances of benzothiadiazole (BDT) and its derivatives have raised considerable attention for optical applications and molecular electronics. BDT molecules are formed by heteroaromatic groups containing nitrogen and sulfur atoms. These latter species provide a remarkably stable molecular anchoring to the metal electrodes, an electron acceptor character and excellent electronic properties. Electron conductance is also known to improve in extended polymeric structures. Aiming for this goal, bottom-up approach and surface-confined chemical-reaction technique have brought considerable advance in the formation of structures such as graphene nanoribbons, either pristine or n-dopped. Here, we focus on the synthesis of molecular structures with electron acceptor core characterizing the growth of dibromo-benzothiadiazole (DBT) on Cu(110) surface. Low temperature scanning tunneling microscopy experiments performed in ultra-high-vacuum, complemented by density functional theory modeling have been used to characterize the electronic properties of single monomers, extended domains and on-surface polymerized molecules. Specifically, we will address the role of the bromine atoms and the charge transfer on the formation of delocalized π-states along the [1-10] substrate high-symmetry direction, starting from localized molecular states.