[1Da01-09] Surface Science(SS1) Physical Property

[1Da04] Chiral honeycomb lattices of non-planar pi-conjugated supramolecules on Ag(111) surfaces

*Ryohei Nemoto¹, Saya Nakano², Noriaki Takagi³, Masahisa Tsuchiizu², Ryuichi Arafune¹, Rie Suizu^4,5, Takashi Uchihashi¹, Kunio Awaga⁴ (1. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 2. Department of Physics, Nara Women's University, 3. Graduate School of Human and Environment, Kyoto University, 4. Department of Chemistry and IRCCS, Nagoya University, 5. JST PRESTO)

In this study, we discuss about the structural and electronic properties of self-assembled organic molecular monolayers on Ag(111), focusing on the C3 symmetric triptycene derivative: Trip-Phz (see Fig.1) by means of scanning tunneling microscopy (STM) measurements, tight-binding (TB) calculations and density functional theory (DFT) calculations. STM results showed three self-assembled structures in the sub-monolayer region. In particular, the Trip-Phz honeycomb lattice showed 7x7R21.8° /R38.2° superstructures on the Ag(111) surface. The three-fold symmetry of the Trip-Phz molecule and the symmetry of the honeycomb lattice shows that they form a Kagome lattice when the bonding points between the molecules are taken as vertices. As results of TB calculations, the band structure of the Kagome lattice has not only the Dirac band, but also a flat band. Moreover, The results of DFT calculations indicated the Dirac-like band and a flat band are maintained even on the Ag(111) substrate.