Nonintuitive Surface Self-Assembly of Functionalized Molecules on Ag(111)

Andreas Jeindl, Jari Domke, Lukas Hörmann, Falko Sojka, Roman Forker, Torsten Fritz, Oliver Hofmann*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The fabrication of nanomaterials involves self-ordering processes of functional molecules on inorganic surfaces. To obtain specific molecular arrangements, a common strategy is to equip molecules with functional groups. However, focusing on the functional groups alone does not provide a comprehensive picture. Especially at interfaces, processes that govern self-ordering are complex and involve various physical and chemical effects, often leading to unexpected structures, as we showcase here on the example of a homologous series of quinones on Ag(111). Naively, one could expect that such quinones, which all bear the same functionalization, form similar motifs. In salient contrast, our joint theoretical and experimental study shows that profoundly different structures are formed. Using a machine-learning-based structure search algorithm, we find that this is due to a shift of the balance of three antagonizing driving forces: adsorbate–substrate interactions governing adsorption sites, adsorbate–adsorbate interactions favoring close packing, and steric hindrance inhibiting certain otherwise energetically beneficial molecular arrangements. The theoretical structures show excellent agreement with our experimental characterizations of the organic/inorganic interfaces, both for the unit cell sizes and the orientations of the molecules within. The nonintuitive interplay of similarly important interaction mechanisms will continue to be a challenging aspect for the design of functional interfaces. With a detailed examination of all driving forces, we are, however, still able to devise a design principle for self-assembly of functionalized molecules.
Original languageEnglish
Pages (from-to)6723–6734
JournalACS Nano
Volume15
Issue number4
DOIs
Publication statusPublished - 17 Mar 2021

Keywords

  • organic/inorganic interface
  • density functional theory
  • scanning tunneling microscopy
  • low energy electron diffraction
  • structure prediction
  • design principle
  • molecular driving forces

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)
  • Materials Science(all)

Fields of Expertise

  • Advanced Materials Science

Cooperations

  • NAWI Graz

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