Electrical bistability switching in lanthanides based organometallic complexes: influence of the symmetry structure of the ligand. (Abstract/Poster in convegno)

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  • Electrical bistability switching in lanthanides based organometallic complexes: influence of the symmetry structure of the ligand. (Abstract/Poster in convegno) (literal)
Anno
  • 2010-01-01T00:00:00+01:00 (literal)
Alternative label
  • Laura Zulian 1 , Umberto Giovanella1, Mariacecilia Pasini , Silvia Destri1, Chiara Botta1 (2010)
    Electrical bistability switching in lanthanides based organometallic complexes: influence of the symmetry structure of the ligand.
    in TRANS'ALP NANO 2010 Conference on Nanoscience and Nanotechnologies,, COMO, 03-05-GIU-2010
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Laura Zulian 1 , Umberto Giovanella1, Mariacecilia Pasini , Silvia Destri1, Chiara Botta1 (literal)
Note
  • Poster (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Laura Zulian 1 , Umberto Giovanella1, Mariacecilia Pasini , Silvia Destri1, Chiara Botta1 ISMAC-CNR (literal)
Titolo
  • Electrical bistability switching in lanthanides based organometallic complexes: influence of the symmetry structure of the ligand. (literal)
Abstract
  • Abstract: During the past ten years, the field of organic electronics has witnessed giant step forwards. Light emitting diodes, photovoltaic cells and transistor based on organic material have in fact aroused considerable interest because of the unique advantages provided by the these materials like low fabrication cost, high mechanical flexibility and versatility of the chemical structures [1],[2]. In this field, another emerging, promising but still at the exploration stage research area is that of electronic organic memories [3]. An organic memory device stores information in a manner entirely different from that of silicon devices. Rather than encoding \"0\" and \"1\" as the amount of charge stored in a cell, organic memory stores data, for instance, based on the high and low conductivity response to an applied voltage (electrical bistability). The conductance switching has been attributed from time to time to different mechanism ranging from trappingdetrapping phenomena [4] to conformational change [5], from charge transfer [6] to filamentary conduction [7]. Anyway despite large efforts in the scientific community, the mechanism and the intriguing behaviour of electrical bistability and memory switching is still far from being completely understood. In particular it was believed that material structure and morphology can affect significantly the origin of the switching mode. However a systematic study on establishing the relationships between chemical structure, material morphology and memory characteristic has not fully exploited yet. Up to now different memory devices based on organic molecules were investigated in order to obtain the realization of an high performances memory devices for industrial application. One of the best results has been obtained with a blend between Poly(N-vinyl carbazole) (PVK) (Fig. 1 (D)), a semiconducting polymer, and some organolanthanide complexes but a clear explanation of their behaviour and functioning are still lacking. In this work we investigate the resistance switching phenomenon in a series of organometallic compound reported in Fig. 1 (B) and (C). In these complexes we maintain phenantroline as ancillary ligand while we change both the lanthanide ions (Gd3+, Sm3+, Eu3+) and the ionic ligand structure by using a Thienoyltrifluoroacetone (TTA) (an asymmetric ligand) or 1,3-Di-(2-Thienyl)-1,3-Propanedione (DPA) (a symmetric ligand). The architecture of the devices based on indium-thin-oxide (ITO)/PVK:rare earth complex/Al is also reported in Fig. 1(A). By variation of the lanthanide ion and ligands a large number of different devices with an ITO/organic layer/Al configuration were studied. In Fig. 2 the I-V characteristic curves relative to ITO/PVK:Gd(Phen)(DTP)3/Al (panel A), ITOPVK:Gd(Phen)(TTA)3/Al (panel B) have been reported as an example. For the ITO/PVK:Gd(Phen) (DTP)3/Al it can be seen (Fig. 2, panel A) that the current increases progressively with the bias voltage and is high (high-conductance state, ON state). As the voltage is increased further, a sharp decrease in the current from 10-1 to 10-4 A occurs at about 11 V, and the current keeps the low-conductance state (OFF state) with the current to decrease to 0, indicating the transition of the devices from the ON state to OFF state. (literal)
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