Orbital Mapping of Semiconducting Perylenes on Cu(111)

Abstract

Semiconducting O-doped polycyclic aromatic hydrocarbons constitute a class of molecules whose optoelectronic properties can be tailored by acting on the πextension of the carbon-based frameworks and on the oxygen linkages. Although much is known about their photophysical and electrochemical properties in solution, their selfassembly interfacial behavior on solid substrates has remained unexplored so far. In this paper, we have focused our attention on the on-surface self-assembly of O-doped biperylene derivatives. Their ability to assemble in ordered networks on Cu(111) singlecrystalline surfaces allowed a combination of structural, morphological, and spectroscopic studies. In particular, the exploitation of the orbital mapping methodology based on angleresolved photoemission spectroscopy, with the support of scanning tunneling microscopy and low-energy electron diffraction, allowed the identification of both the electronic structure of the adsorbates and their geometric arrangement. Our multi-technique experimental investigation includes the structure determination from powder X-ray diffraction data for a specific compound and demonstrates that the electronic structure of such large molecular self-assembled networks can be studied using the reconstruction methods of molecular orbitals from photoemission data even in the presence of segregated chiral domains.

Systematic arrangement control of functional organic molecules

“…Functional organic molecules with tunable properties are composed of earth-abundant and readily available building blocks (C, H, O, N, and S). 1 One of the typical examples is π-conjugated molecules, which exhibit luminescence and conductivity owing to their interaction with light [2][3][4][5][6][7][8] and their electron transport capabilities, [9][10][11][12][13][14][15][16] respectively. As a result, they are expected to play an important role in a variety of research fields, including electroluminescence, 2,6-8 photovoltaics, 9,10 electronics, 11 and energy production and storage.…”

Direct observation of narrow electronic energy band formation in 2D molecular self-assembly

“…There have been indications of a narrow bandwidth (<20 meV) energy dispersion resulting from direct intermolecular hybridisation in a 2D molecular self-assembly on a weakly interacting metal; however, such narrow band structure has not been clearly resolved nor quantitatively modeled. 35 In the case where molecule-molecule interactions can be omitted, ARPES of 2D self-assembled molecular monolayers can retrieve the real-space morphology of molecular orbitals (MOs) via orbital tomography, [36][37][38][39] also providing information on molecule-surface charge transfer and energy level alignment. [40][41][42] In this work, we resolve, via ARPES measurements at room temperature, the narrow bandwidth ($20 meV) electronic energy dispersion resulting from in-plane inter-HOMO hybridization within a 2D self-assembled ML of MgPc on Ag(100).…”