Molecular Electronics
•Download as PPTX, PDF•
4 likes•6,244 views
It is a brief overview on molecular electronics with special focus to molecular rectifiers.
Recommended
More Related Content
What's hot
What's hot (20)
Viewers also liked
Similar to Molecular Electronics
Similar to Molecular Electronics (20)
More from Saurav Ch. Sarma
More from Saurav Ch. Sarma (9)
Recently uploaded
Recently uploaded (20)
Molecular Electronics
- 1. THE GENESIS OF MOLETRONICS Saurav Chandra Sarma 1
- 2. Introduction Introduction Molecular Rectifiers Fabrication of molecular junction Some common terms Factors affecting Conductance Research Highlights Other molecular Devices Conclusion 2 Sketch of my talk Molecular Rectifiers Fabrication Research Highlights Logic Gates Molecular Switches Molecular Wires Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 3. 3 Moore’s Law 3The Wall Street Journal The number of transistor that can be placed on a single integrated circuit double about every two year. Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 5. • Term coined by Mark Ratner, in 1974. • Can be defined as technology utilizing Single molecules, Small groups of molecules, Carbon nanotubes, or Nanoscale metallic or Semiconductor wires to perform electronic functions. Molecular Electronics • This device must exchange information, or transfer states or must be able to interface with components at the macroscopic level. • Usually consist of organic molecules sandwiched between conducting electrodes. 5 Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 6. 1959 1971 1974 Late 1970s 1980s 1997 2000 R. Feynmann lecture Kuhn and Mann experiment Aviram and Ratner first paper on moletronics Conferences arranged by F. Carter Shirakawa, Heeger and MacDiarmid awarded Nobel Prize in Chemistry First attempt to measure single molecule transport by Reed and Tour Development of STM and AFM by IBM Pioneers of Moletronics
- 7. Bottom-Up ( Why molecules..??) 7 Speed: Good molecular wires can reduce the transit time of typical transistors. New functionalities: New property can easily be assigned to a molecule that are not possible to implement in conventional solid state physics. Flexibility: Pi conjugation and therefore conduction can be switched on and off by changing molecular conformation providing potential control over electron flow. Self-assembly: Can create large arrays of identical devices. Size: Molecules are small that leads to higher packing density of devices. Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 9. What is a Rectifier…??? 9 HALF-WAVE RECTIFIER RECTIFIERS: It converts alternating waveform to direct waveform. Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 10. First pioneering paper in Moletronics 10Aviram, A. et. al., Chem. Phys. Lett. 29, 277–283 (1974). Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 11. Proposal of Molecular Rectifier An organic molecule to have rectifier properties should have roughly the properties of p-n junction. 11Aviram, A. et. al., Chem. Phys. Lett. 29, 277–283 (1974). By the use of EDG/EWG substituents in the aromatic ring, we can increase/decrease electron density in the aromatic ring and thus create p- type and n-type molecular junctions. Hemiquinone Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 12. Mechanism of rectification by substitution group 12
- 13. 13Aviram, A. et. al., Chem. Phys. Lett. 29, 277–283 (1974) Alligator group Molecular bridge Left electrode Right electrode Potential Barrier Energy Levels D A
- 14. Y X Zero Biased 14Aviram, A. et. al., Chem. Phys. Lett. 29, 277–283 (1974) D AX=EDG Y= EWG D= Donor half A= Acceptor half
- 15. Y X V I Forward Biased Current Flows 15 X=EDG Y= EWG D= Donor half A= Acceptor half
- 16. Y X X=EDG Y= EWG D= Donor half A= Acceptor half V I Reverse Biased No Current Flows 16 D A
- 17. Fabrication of molecular junction DEPOSITION TECHNIQUE: Self-assembled monolayer (SAM) Langmuir-Blodgett (LB) Technique SOPHISTICATED TECHNIQUES: The size of the molecule is less than the resolution of the lithographic method Following sophisticated techniques are used: • Electro-migration technique • Scanning Probe technique • Mechanically Controllable break-junctions (MCBJs) 17 Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 18. Langmuir- Blodgett film technique • LANGMUIR-BLODGETT (LB) TECHNIQUE : A LB film consists of one or more monolayers of an organic material, deposited from the surface of a liquid onto a metal surface by immersing the the solid substrate into the liquid. 18 Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 19. Self-assembly monolayer technique • SELF-ASSEMBLED MONOLAYERS (SAM): The substrate covered with the metal layer is dipped into the molecular solution. Ampiphilic molecules equipped with one anchoring group adsorbs chemically onto the metal surface. 19 Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 20. Mechanically Controllable Break Junction technique 20Reed et. al., Science, 278, 252-253 (1997) Schematic of MCB junction a Bending beam b Counter support c Notched gold-wire d Glue contacts e Piezo-element f Glass tube containing solution Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 21. • Changing the environment around the electrodes. • Changing the alligator group attached to the metal electrode • Inducing asymmetry in the molecular design. Rectification Ratio 21 • Rectification Ratio can be defined as the ratio of the current at conducting voltage to the current at insulating voltage. RR= 𝐼(𝐶𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑛𝑔 𝑏𝑖𝑎𝑠) 𝐼(𝐼𝑛𝑠𝑢𝑙𝑎𝑡𝑖𝑛𝑔 𝑏𝑖𝑎𝑠) Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 22. Conductance Quantum 22 • Conductance given by the Landauer expression G= 2𝑒2 ℎ Σ𝑇𝑖 G= Conductance Ti=Transmission probabilities in the conductance channels. • Monovalent metal single atom ( such as Au, Cu and Ag ) possess a single channel for electron transmission. Therefore, Conductance Quantum= 1 G0 = 2𝑒2 ℎ Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 23. Conductance Trace • It is the graph of conduction as a function of electrode separation. 23https://www.weizmann.ac.il/chemphys/orental/research.html Conductance histogramConductance vs. Displacement graph Repeated ‘n’ times Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 24. Conductance Quantization at molecular level 24Tao et. al., Science, 301, 1221-1223 (2003) Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion Electrode Separation X
- 25. Alkanedithiols: SHHS RC6=10.5 MW HS SH N=6: N=8: RC8=51 MW SHHS N=10: RC10=630 MW Factor affecting molecular conductance- Chain Length 25Zhou et. al., J Chem. Phys., 128, 044704-907 (2008) G(L) = Ae-βL Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 26. Effect of Twist angle 26Venkataraman et. al., Nature, 442, 904-907 (2006) G α cos2θ Conductance for the series decreases with increasing twist angle Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 27. Factor affecting molecular conductance- Aromaticity 27Chen et al, JACS 442, 918-920 (2014) Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion The highest conductance is achieved by structure that can easily acquire quinoid like structure and hence attain a better coupling between gold electrodes and other cyclic units.
- 28. 28Ratner, A. et. al., Nano Lett., 15 (3), 1577–1584 (2015) New design of molecular rectifier Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 29. Fermi-Level Pinning 29Ratner, A. et. al., Nano Lett., 15 (3), 1577–1584 (2015) • Energy offset between the electrode fermi-level and the frontier orbital of the molecule is unchanged even when bias is applied. Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion Transmission Window
- 30. 30Ratner, A. et. al., Nano Lett., 15 (3), 1577–1584 (2015) New design of molecular rectifier Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion Transmission Window
- 31. The environment does the trick 31Venkataraman, L. et al. Nat. Nanotechnol. 10, 522–527 (2015) Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 32. The environment does the trick Single-molecule junctions with high rectification ratios can be realized by exposing different electrode surface areas to an ionic liquid. 32Venkataraman, L. et al. Nat. Nanotechnol. 10, 522–527 (2015) Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion Polar Solvent Non-Polar Solvent
- 33. 33Whitesides, G. et. al., J. Am. Chem. Soc., 133 (39), 15397–15411 (2011) Molecular half-wave rectifier Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion S Fc2
- 34. 34Whitesides, G. et. al., J. Am. Chem. Soc., 133 (39), 15397–15411 (2011) Molecular half-wave rectifier Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion S Fc
- 35. 35Whitesides, G. et. al., J. Am. Chem. Soc., 133 (39), 15397–15411 (2011) Molecular half-wave rectifier Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion S CH3
- 36. 36Whitesides, G. et. al., J. Am. Chem. Soc., 133 (39), 15397–15411 (2011) Molecular half-wave rectifier Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 37. 37Nijhuis, C. et. al., Nano Lett., 10, 3611—3619 (2010) Mechanism of Rectification Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 38. Other Molecular Devices 38Venkataraman, L. et. al., Nano Lett., 11 (4), 1575–1579 (2011) A Single molecule potentiometer Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion Higher conductance state: Electrode Olefin SulfideElectrode Low conductance state: ElectrodeSulfide Olefin Sulfide Electrode
- 39. 39 Other molecular devices Molecular Wires Molecular Switches Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion Cuerva et. al., Nanoscale, 3, 4003-4014 (2011)
- 40. Challenges of moletronics 40 Stability of molecules. Reproducibility of results. Controlled fabrication within specified tolerances. Hard experimental verification. Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
- 41. 41 “The Next Big Thing is very, very small Trillions of transistors THz processors Infinite storage capacity High computation power Concluding Remarks It is the birth of a new technological revolution And the death of silicon” Introduction Molecular Rectifiers Fabrication Common Terms Factors Research Highlights Molecular Devices Conclusion
Editor's Notes
- The rise in the popularity of electric bicycles cannot be understated, especially in places where congested roads or high gas prices make car ownership unaffordable for many. So while many automakers and technology companies are focusing on building big battery packs for electric vehicles, Britain’s Faradion went a different route, building an electric bicycle to prove its sodium-ion battery concept really works, reports Green Car Congress.
- It was suggested in a 1959 lecture by the eminent physicist and visionary, Richard Feynman:
- Moore's Law was made in the form of an observation and forecast . Gordon Moore delivering a lecture in the 1970s. ‘Moore’s Law,’ which he introduced in 1965, took hold as an axiom in Silicon Valley and as general shorthand for just about any kind of progress, technological or otherwise. PHOTO:INTEL
- It was suggested in a 1959 lecture by the eminent physicist and visionary, Richard Feynman:
- 1971: These measurements showed that the conductivity decreased exponentially with layer thickness, therefore revealing electron tunnelling through the organic monolayer. In 1980s: It quickly became clear that these tools could be used to measure the conductance of single molecules In 1990s: The first significant work attempting to measure single-molecule transport came from Mark Reed’s group at Yale University, working in collaboration with James Tour’s group, then at the University of South Carolina.
- Whereas electrons moving in silicon have many possible energies that will facilitate jumping from device to device, electron energies in molecules and atoms are quantized - there is a discrete number of allowable energies.
- The most interesting and historic use of a rectifier that I can think of is a "cat's whisker" (which has nothing to do with cats!), it was used to convert AM (amplitude modulation) radio signals into audio signals that could be heard through headphones over a hundred years ago. Other uses include voltage multiplier circuits that can produce thousands of volts from a small oscillating voltage. High voltages are needed in xray machines, electron microscopes, IC manufacturing and old CRT televisions. The most familiar use will be in low voltage power adaptors to convert AC into DC. A rectifier allows current to pass in only one direction (limited by it's PIV, peak inverse voltage, when this is exceeded it will break down).
- It was suggested in a 1959 lecture by the eminent physicist and visionary, Richard Feynman: A direct measurement of the conductivity of a molecular wire can be provided by atomic force microscopy JChemEd.chem.wisc.edu • Vol. 78 No. 3 March 2001 • Journal of Chemical Education
- It was suggested in a 1959 lecture by the eminent physicist and visionary, Richard Feynman: A direct measurement of the conductivity of a molecular wire can be provided by atomic force microscopy JChemEd.chem.wisc.edu • Vol. 78 No. 3 March 2001 • Journal of Chemical Education
- It was suggested in a 1959 lecture by the eminent physicist and visionary, Richard Feynman: A direct measurement of the conductivity of a molecular wire can be provided by atomic force microscopy JChemEd.chem.wisc.edu • Vol. 78 No. 3 March 2001 • Journal of Chemical Education
- When size of metallic single atom contacts is comparable to the Fermi wavelength
- Science,2003,301,1221
- Experiment: Venkataraman et al, Nature 442, 904 (2006) Theory: S. Y. Quek, H. J. Choi et al, Nano Letters 9, 3949 (2009).
- Nano Lett. 2015, 15, 1577−1584
- Nano Lett. 2015, 15, 1577−1584
- NATURE NANOTECHNOLOGY | VOL 10 | JUNE 2015
- J. Am. Chem. Soc. 2011, 133, 15397–15411
- J. Am. Chem. Soc. 2011, 133, 15397–15411
- J. Am. Chem. Soc. 2011, 133, 15397–15411
- |J. Am. Chem. Soc. 2011, 133, 15397–15411
- RR=130, Molecule= SC11Fc
- It was suggested in a 1959 lecture by the eminent physicist and visionary, Richard Feynman: A direct measurement of the conductivity of a molecular wire can be provided by atomic force microscopy JChemEd.chem.wisc.edu • Vol. 78 No. 3 March 2001 • Journal of Chemical Education