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Single Molecule Electronics

Single Molecule Electronics. Kasper Moth-Poulsen, Chalmers University of Technology September 2013 Kasper.moth-poulsen@chalmers.se. MCC075 Molecular Electronics. Outline. Lecture 1 Background and Motivation Experimental Methods. Lecture 2 (Friday)

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Single Molecule Electronics

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  1. Single Molecule Electronics Kasper Moth-Poulsen, Chalmers University of Technology September 2013 Kasper.moth-poulsen@chalmers.se MCC075 Molecular Electronics

  2. Outline Lecture 1 Background and Motivation Experimental Methods Lecture 2 (Friday) Molecular Design of Diodes, Switches etc. Part 3 Self-assembly

  3. What did we learn last time?

  4. Statistics “Contacting Individual Molecules Using Mechanically Controllable Break Junctions” Jan van Ruitenbeek, Lecture Notes in Physics 680, 253-271 (2005)

  5. The Vision II: Aviram and Ratner • “the molecular rectifier” A. Aviram and M. A. Ratner, “Molecular Rectifiers” Chem. Phys. Lett. Vol. 29, pp. 277-283, 1974.

  6. A. Aviram and M. A. Ratner, “Molecular Rectifiers” Chem. Phys. Lett. Vol. 29, pp. 277-283, 1974.

  7. Solution Based Systems Rotaxanes Initially No electrodes directly involved Fraser Stoddard and co-workers eg early work: Pure &App/. Chem.,Vol. 65, No. 11, pp. 2351-2359,1993.

  8. Important factors for the single molecule systems The chemical anchor point: controls the self-assembly and is of paramount importance for the nature of the electron transport Molecular orbitals Interface Electrodes Nature Nanotech. 4 (9), 551-556, 2009

  9. Nature Nanotech. 4 (9), 551-556, 2009

  10. Nature Nanotech. 4 (9), 551-556, 2009

  11. Importance of the chemicalcontacts Nano Letters 8 (1) 1-5,2008. Nature Nanotech. 4 (9), 551-556, 2009.

  12. Solid state device Resistance ~1 GΩ range 0.2-1 MΩ b ~0,63 Å-1 ~0,39 Å-1 STM measurement Nano Letters 8 (1) 1-5,2008. Nature Nanotech. 4 (9), 551-556, 2009.

  13. Intermezzo: Chemistry 101Orbitals in Carbon and Chemical Bonds

  14. Molecular Back-bone: does it matter? Optical band gaps for ”infinite” polymers obtained by extrapolation of monodisperseoligomers 2.5 - 2.8 eV 2.3 eV 1.4 - 1.8 eV 2.2 -3.2 eV nsat= 20 nsat= 10 Calculation 3.8 - 3.9 eV 3.3 - 3.5 eV 5.7 eV nsat= 2 nsat= 9 nsat= 10 Slide courtesy of prof. MB Nielsen, Univ. Copenhagen

  15. Molecular Back-bone: does it matter? Kushmerik, TS Mayer and co-workers J. Phys. Chem. B 2004, 108, 2827-2832

  16. Molecular Back-bone: does it matter?

  17. Tunnellingvs Hopping, where is the transition from small molecules to polymers? Seong Ho Choi, BongSoo Kim, C. Daniel Frisbie, Science 2008

  18. Tunnellingvs Hopping Hopping is temperature dependent Tunnelling is NOT temperature dependent Seong Ho Choi, BongSoo Kim, C. Daniel Frisbie, Science 2008

  19. Molecular Switches, 3 types 1) Conformation switches 2) Electronic switches 3) Translational switches

  20. Conformational Switch “Microfabricated Molecular Break Junction” Emanuel Lörtscher, Jacob W. Ciszek, James Tour, and Heike Riel, Small2006, 2, No. 8-9, 973 – 977

  21. Switch No-Switch Emanuel Lörtscher, Jacob W. Ciszek, James Tour, and Heike Riel, Small2006, 2, No. 8-9, 973 – 977

  22. “Switching Driven by rotation in the central bond in the bipyridine unit, induced by alignment of the dipoles in the Nitro groups with the electric field” Ferdinan Evers and co-workers small 2009, 5, No. 19, 2218–2223

  23. Conductivity and torsion angle: detailed investigation Conductivity vs torsion angle Mayor, Wandlowski and co-workers Nano Lett. 2010, 10, 156-163

  24. Molecular Switches, 3 types 1) Conformation switches 2) Electronic switches 3) Translational switches

  25. Source Drain 3-terminal devices Tunneling barrier Tunneling barrier ”Diamond plot”

  26. Kubatkin et al. Nature 2003

  27. Molecular Back-bone: does it matter? Optical band gaps for ”infinite” polymers obtained by extrapolation of monodisperseoligomers 2.5 - 2.8 eV 2.3 eV 1.4 - 1.8 eV 2.2 -3.2 eV nsat= 20 nsat= 10 Calculation 3.8 - 3.9 eV 3.3 - 3.5 eV 5.7 eV nsat= 2 nsat= 9 nsat= 10 Electrondelocalization via crossconjugation is lessefficientthan via linear conjugation Slide courtesy of prof. MB Nielsen, Univ. Copenhagen

  28. Cross-conjugation, where does it come from? • It is all pz orbitals so why is the delocalization different? So surprizing that the physists has come up with their own name for it: “Quantum interference” Chemist might say: we have known about it all the time: ortho/paravs meta directing? Michael addition?

  29. Position of the Anchor Groups para: linear conjugation meta: cross conjugation Smaller conductance (by 2 orders of magnitude) M. Mayor, H.B. Weber, J. Reichert, M. Albing, C. von Hänisch, D. Beckmann, M. Fischer, Angew. Chem. Int. Ed. 2003, 42, 5834-5838.

  30. Switching via changes in electronic states: Cross Conjugation and Quantum Interference Hummelen and Solomon dx.doi.org/10.1021/ja202471m |J. Am. Chem. Soc. XXXX, XXX, 000–000

  31. Synthesis and initial Charactarisation: Hummelen and co-workers Org. Lett., 2006, 8 (11), pp 2333–2336 Transport and Thery „evidence of Quantum Interference” JACS ASAP 2011 dx.doi.org/10.1021/ja202471m Ox Red Brønsted-Nielsen and co-workers Org. Lett. 2006 Vol. 8, No. 6 1173-1176 J. Org. Chem, Vol. 73, No. 8, 2008

  32. Conjugation/cross conjugation photoswitch D. Dulic , S. J. Van Der Molen, T. Kudernac , H. T. Jonkman , J. J. D. de Jong , T. N. Bowden , J. van Esch , B. L. Feringa , B. J. van Wees , Phys. Rev. Lett. 2003 , 91 , 207402 .

  33. Molecular Switches 1) Conformation switches 2) Electronic switches 3) Translational switches

  34. Dripling C60 for six weeks Danilov/Kubatkin

  35. D Hedegård

  36. Danilov and Kubatkin, NANO LETTERS    Volume: 8    Issue: 8    Pages: 2393-2398  

  37. TPS • We have discussed 3 types of switches, describe each type of Switch

  38. How to Switch a Molecular Switch • 1) thermal activation • 2) level allignment (gating) • 3) redox chemistry with reorganisation • 4) photoreaction • 5) magnetic switch

  39. level allignment (gating) Kubatkin nature 2003

  40. Redox Switch

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