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Stuart.Lindsay@ASU.EDU Interfacing Molecules to Electronic Materials
Artificial Enzymes Hydrogen generation, photovoltaics + + + + + + + + + + + + + + + Steinberg-Yfrach et al. Nature 392, 479 (1998)
1. Make functional molecules 2. Wire molecules to electrodes Steps to bio/molecular electronics: 3. Make them function on electrodes like they do in solution 4. Make economically-viable devices
Test Case: Single Molecule Switch made from Oligo Aniline Insulator i V Conductor -2e - Insulator -2e - Single Molecule Switch?
Molecular electronics vs. solution charge transfer chemistry Charge transfer in nature in solution + ions. Charge transfer in molecular electronics electrode to electrode – No water/ions
1 2 LUMO HOMO CHARGED Why solvent + ions matter e-e- ENERGY e-e- LANDAUER MARCUS
Charge Transfer in DNA Barnett et al., Science 294 567 (2001)
The Challenge Need to measure single molecule conductance in a conducting solution with independent control of charge state. How to do this?
Repeated break junction Xu and Tao, Science 301, 1221-1223 (2003)
Wiring Single Molecules Reliably Cui et al. Science 274 571 (2001) Xu and Tao, Science 301 1221 (2003) GOOD NEWS: 7000:1 G range – worst G theor /G meas is 3.3 BAD NEWS: All Landauer theory
Operating probes in electrolyte Rev. Sci. Instrum. 60, 3128 - 3130 (1989) (DNA - Xu et al. Nanoletts 4 1105 2004) Insulating layer
Controlling ion gradients/electric fields at an electrode surface Bigger ion gradient = Bigger electric field at molecule
Measuring transport as a function of oxidation state LOCAL FIELD SURFACE FIELD
Electrochemical Current Surface Potential, E S, V vs. Ag Molecular Conductance (nS) G=G MAX - a(E S -b) 2 InsulatorConductorInsulator TIP-SUBSTRATE V FIXED AT 50mV Ofer et al. JACS 112 7869, 1990
Neutral molecule - -- --- Current (nA) Tip-substrate bias (V) (NO IONS) FIX E S, VARY TIP FIELD Oxidized molecule E S =0.4V (H 2 SO 4 )
G=G max -a(E S -b) 2 E S (V) =E S - V =1.4 E S =0.3V E S =0.25V Tip-substrate bias (V) Current (nA) ------ MOLECULE FIELD = SURFACE FIELD ± TIP FIELD
We have a two terminal switch!
Current (nA) V ts (Volts) E S (V vs. Ag Wire) --- But it will need more than one molecule: Bias sweeps Potential sweeps
Summary Made a low-voltage switch based on chemical knowledge, get NDR Probe role of fluctuations Roadmap for going from chemistry to molecular electronics
1 Molecular Electronics Aviram-Ratner Diode: an acceptor-bridge-donor molecule Chem.Phys.Lett. (1974) 29, Electrode charge-injection to donor 2.Donor-Acceptor.
Introduction to Electroanalytical Chemistry
Electric Potential Energy & Voltage.. Battery Battery : A battery is a combination of electrochemical cells connected together. What does an electrochemical.
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Chapter 20 Electrochemistry
Electrochemistry Experiment 12. Oxidation – Reduction Reactions Consider the reaction of Copper wire and AgNO 3 (aq) AgNO 3 (aq) Ag(s) Cu(s)
Electrochemistry The study of chemical reactions that produce electrical current or are driven to occur by applying an electrical current. Chemical potential.
Various trajectories through the potential energy surface.
Introduction to Current Electricity and Circuits.
Figure Experimental setup of a mechanically controllable break- junction with (a) the flexible substrate, (b) the counter supports, (c) the notched.
By: Adam Krause 4/17/07 Physics 672
10.3 Electric Potential. Electric Potential Electric potential refers to the amount of energy that electrons possess in a circuit.
Electricity Mr. Dunnum Physical Science. Positive and Negative Charge An atom becomes negatively charged when it gains extra electrons. If an atom loses.
Chapter 20 Electricity. Section 1 Electric charge and static electricity.
Electric Current AP Physics C Montwood High School R.Casao.
An Introduction to Electroanalytical Chemistry Electrochemistry: The study of the interchange of chemical and electrical energy Oxidation is the loss of.
Huckel I-V 3.0: A Self-consistent Model for Molecular Transport with Improved Electrostatics Ferdows Zahid School of Electrical and Computer Engineering.
Chapter 17.2 – Current electrical potential energy –
Introduction to electrochemical systems Sähkökemian peruseet KE Tanja Kallio C213 CH 1.
Electrochemical Reactions. Anode: Electrons are lost due to oxidation. (negative electrode) Cathode: Electrons are gained due to reduction. (positive.
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