Selective self-assembly of 2,3-diaminophenazine molecules on MoSe₂ mirror twin boundaries

The control of the density and type of line defects on two-dimensional (2D) materials enable the development of new methods to tailor their physical and chemical properties. In particular, mirror twin boundaries (MTBs) on transition metal dichacogenides have attracted much interest due to their metallic state with charge density wave transition and spin-charge separation property. In this work, we demonstrate the self-assembly of 2,3-diaminophenazine (DAP) molecule porous structure with alternate L-type and T-type aggregated configurations on the MoSe₂ hexagonal wagon-wheel pattern surface. This site-specific molecular self-assembly is attributed to the more chemically reactive metallic MTBs compared to the pristine semiconducting MoSe₂ domains. First-principles calculations reveal that the active MTBs couple with amino groups in the DAP molecules facilitating the DAP assembly. Our results demonstrate the site-dependent electronic and chemical properties of MoSe₂ monolayers, which can be exploited as a natural template to create ordered nanostructures.