Control of the dipole layer of polar organic molecules adsorbed on metal surfaces via different charge-transfer channels

Meng Kai Lin, Yasuo Nakayama, Ying Jie Zhuang, Kai Jun Su, Chin Yung Wang, Tun Wen Pi, Sebastian Metz, Theodoros A. Papadopoulos, T. C. Chiang, Hisao Ishii, S. J. Tang

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Organic molecules with a permanent electric dipole moment have been widely used as a template for further growth of molecular layers in device structures. Key properties of the resulting organic films such as energy level alignment (ELA), work function, and injection/collection barrier are linked to the magnitude and direction of the dipole moment at the interface. Using angle-resolved photoemission spectroscopy (ARPES), we have systematically investigated the coverage-dependent work function and spectral line shapes of occupied molecular energy states (MESs) of chloroaluminium-phthalocyanine (ClAlPc) grown on Ag(111). We demonstrate that the dipole orientation of the first ClAlPc layer can be controlled by adjusting the deposition rate and postannealing conditions, and we find that the ELA at the interface differs by ∼0.4eV between the Cl up and down configurations of the adsorbed ClAlPc molecules. These observations are rationalized by density functional theory (DFT) calculations based on a realistic model of the ClAlPc/Ag(111) interface, which reveal that the different orientations of the ClAlPc dipole layer lead to different charge-transfer channels between the adsorbed ClAlPc and Ag(111) substrate. Our findings provide a useful framework toward method development for ELA tuning.

Original languageEnglish
Article number085425
JournalPhysical Review B
Volume95
Issue number8
DOIs
StatePublished - 17 Feb 2017

Keywords

  • martensitic phase transformation
  • microwires
  • shape memory alloys
  • superelastic strain

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