- Controlling Single Molecule Conductance by a Locally Induced Chemical Reaction on Individual Thiophene Units
-
Among the prerequisites for the progress of single-molecule-based electronic devices are a better understanding of the electronic properties at the individual molecular level and the development of methods to tune the charge transport through molecular junctions. Scanning tunneling microscopy (STM) is an ideal tool not only for the characterization, but also for the manipulation of single atoms and molecules on surfaces. The conductance through a single molecule can be measured by contacting the molecule with atomic precision and forming a molecular bridge between the metallic STM tip electrode and the metallic surface electrode. The parameters affecting the conductance are mainly related to their electronic structure and to the coupling to the metallic electrodes. Here, the experimental and theoretical analyses are focused on single tetracenothiophene molecules and demonstrate that an in situ-induced direct desulfurization reaction of the thiophene moiety strongly improves the molecular anchoring by forming covalent bonds between molecular carbon and copper surface atoms. This bond formation leads to an increase of the conductance by about 50 % compared to the initial state.
- Arnau, Andrés,Borca, Bogdana,Jelínek, Pavel,Kern, Klaus,Klauk, Hagen,Kraft, Ulrike,Michnowicz, Tomasz,Mutombo, Pingo,Pétuya, Rémi,Pentegov, Ivan,Pristl, Marcel,Schendel, Verena,Schlickum, Uta,Wahl, Peter
-
-
Read Online
- Low-voltage organic transistors based on tetraceno[2,3- b ]thiophene: Contact resistance and air stability
-
The small-molecule organic semiconductor tetraceno[2,3-b]thiophene has been synthesized through an environmentally friendly synthetic route, utilizing NaBH4, rather than Al/HgCl2, for the reduction of the quinone. Low-voltage organic thin-film transistors (TFTs) have been fabricated using tetraceno[2,3-b]thiophene and, for comparison, pentacene and anthradithiophene as the semiconductor. The tetraceno[2,3-b]thiophene TFTs have an effective field-effect mobility as large as 0.55 cm2 V-1 s-1 and a subthreshold swing of 0.13 V/decade. In addition, it has been found that the contact resistance of the tetraceno[2,3-b]thiophene TFTs is substantially smaller than that of the anthradithiophene TFTs and similar to that of the pentacene TFTs. The long-term air stability of TFTs based on all three semiconductors has been monitored over a period of 12 months. The initial charge-carrier mobility of the tetraceno[2,3-b]thiophene TFTs is ~50% smaller than that of the pentacene TFTs, but as a result of the greater ionization potential and better air stability induced by the terminal thiophene ring condensed at the thiophene-b-bond, the tetraceno[2,3-b]thiophene TFTs outperform the pentacene TFTs after continuous exposure to ambient air for just 3 months.
- Kraft, Ulrike,Anthony, John E.,Ripaud, Emilie,Loth, Marsha A.,Weber, Edwin,Klauk, Hagen
-
-
Read Online
- Organic Semiconductors and Their Manufacture
-
The invention relates to a semiconductor device comprising a compound of the formula I and of the formula XXI, wherein the symbols have the meanings defined in the specification, to the novel compounds of the formula I and XXI and to the use of such a compound as an organic semiconductor for the preparation of an electronic device, and further compounds and devices, as well as other embodiments given in the specification.
- -
-
Page/Page column 19
(2009/12/23)
-