These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Surface morphologies, electronic structures, and Kondo effect of lanthanide(III)-phthalocyanine molecules on Au(111) by using STM, STS and FET properties for next generation devices.
    Author: Katoh K, Komeda T, Yamashita M.
    Journal: Dalton Trans; 2010 May 28; 39(20):4708-23. PubMed ID: 20396817.
    Abstract:
    The crystal structures of double-decker single-molecule magnets (SMMs) LnPc(2) (Ln = Tb(III) and Dy(III); Pc = phthalocyanine) and non-SMM YPc(2) were determined by using single crystal X-ray diffraction analysis. The compounds are isomorphous to each other. The compounds have metal-centers (M(3+) = Tb, Dy, and Y) 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 degrees. Scanning tunneling microscopy (STM) was used to investigate the compounds adsorbed on a Au(111) surface, deposited by using thermal evaporation in ultra-high 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 (STS) images of TbPc molecules at 4.8 K, a Kondo peak with a Kondo temperature (T(K)) of approximately 250 K was observed near the Fermi level (V = 0 V). On the other hand, DyPc, YPc and MPc(2) exhibited no Kondo peak. In order 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 (OFETs) devices. Tb-Pc molecule devices exhibit p-type semiconducting properties with a hole mobility (mu(H)) of approximately 10(-4) cm(2) V(-1) s(-1). Interestingly, the Dy-Pc based devices exhibited ambipolar semiconducting properties with an electron mobility (mu(e)) of approximately 10(-5) and a hole mobility (mu(H)) of approximately 10(-4) cm(2) V(-1) s(-1). This behavior has important implications for the electronic structure of the molecules.
    [Abstract] [Full Text] [Related] [New Search]