Tuning charge transport in polydopamine tetramers via oxidation state and orientation in supramolecular junctions with gold contacts: An ab initio DFT study

Abstract

This work presents a comprehensive computational investigation of gold-polydopamine supramolecular junctions and their electronic properties using density functional theory (DFT) and non-equilibrium Green's functions (NEGF) methodology. Non-covalent interactions between gold and PDA models are described in the slab configuration, and the molecular junction. By modulating the oxidation state, molecular structure, and surface arrangements of the PDA model, we demonstrate the tunability of the electronic structure, which is promising for application in nanodevices. Calculations reveal either metallic or n-type semiconducting behaviour depending on the oxidation state, contrasting the standard n-type characteristics of the PDA. While catechol-PDA shows an n-type semiconductor behaviour both on single Au electrodes and in the supramolecular junction configuration, quinone-PDA exhibits metallic characteristics. Moreover, magnitudes of transmission vary significantly with the structure of the PDA model. Overall, this work advances the understanding of tuning PDA electronics through interfacing with gold contacts.