Direct observation of lanthanide(III)-phthalocyanine molecules on Au(111) by using scanning tunneling microscopy and scanning tunneling spectroscopy and thin-film field-effect transistor properties of Tb(III)- and Dy(III)-phthalocyanine molecules

Keiichi Katoh, Yusuke Yoshida, Masahiro Yamashita, Hitoshi Miyasaka, Brian K. Breedlove, Takashi Kajiwara, Shinya Takaishi, Naoto Ishikawa, Hironari Isshiki, Feng Zhang Yan, Tadahiro Komeda, Masakazu Yamagishi, Jun Takeya

Research output: Contribution to journalArticle

159 Citations (Scopus)

Abstract

The crystal structures of double-decker single molecule magnets (SMM) LnPc2 (Ln = Tb(III) and Dy(III); Pc = phthalocyanine) and non-SMM YPc2 were determined by using X-ray diffraction analysis. The compounds are isomorphous to each other. The compounds have metal centers (M ) Tb3+, Dy3+, and Y3+) sandwiched by two Pc ligands via eight isoindole-nitrogen atoms in a square-antiprism fashion. The twist angle between the two Pc ligands is 41.4°. Scanning tunneling microscopy was used to investigate the compounds adsorbed on a Au(111) surface, deposited by using the thermal evaporation in ultrahigh vacuum. Both MPc 2 with eight lobes and MPc with four lobes, which has lost one Pc ligand, were observed. In the scanning tunneling spectroscopy images of TbPc molecules at 4.8 K, a Kondo peak with a Kondo temperature (TK) of ∼250 K was observed near the Fermi level (V = 0 V). On the other hand, DyPc, YPc, and MPc2 exhibited no Kondo peak. To understand the observed Kondo effect, the energy splitting of sublevels in a crystal field should be taken into consideration. As the next step in our studies on the SMM/Kondo effect in Tb-Pc derivatives, we investigated the electronic transport properties of Ln-Pc molecules as the active layer in top- and bottom-contact thin-film organic field effect transistor devices. Tb-Pc molecule devices exhibit p-type semiconducting properties with a hole mobility (μH) of ∼10-4 cm2 V-1 s-1. Interestingly, the Dy-Pc based devices exhibited ambipolar semiconducting properties with an electron mobility (μe) of ∼10-5 and a μH of ∼10-4 cm2 V-1 s-1. This behavior has important implications for the electronic structure of the molecules.

Original languageEnglish
Pages (from-to)9967-9976
Number of pages10
JournalJournal of the American Chemical Society
Volume131
Issue number29
DOIs
Publication statusPublished - 2009 Jul 29

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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