Kwang S. Kim

Center for Superfunctional Materials

Dept. of Chemistry

Pohang University of Science and Technology

Nano-Sensing,

Nano-Electronics/Spintronics,

and Nano-Optics

Contents

- Functional Molecules/Materials:

Design Strategy toward

* Creation of new paradigms for designing innovative quantum molecular/nanomaterialsystems

* Extending the frontiers of current research in the creation of futuristic electronic/spintronic/optical devices

* Invention of revolutionary technologies for bio-nano-info interfaces

- CAMD Examples: Quantum Theory, DFT, ab initio theory, MD, NEGF

- Nano-recognition: Self-assembly, Self-synthesis

Organic Nanotubes, Metallic Nanostructures (Science)

Ionophores, Receptors, Enzymes; Fullerenes, CNT, Nanotori

Nanomechanical Devices, Photoswitches, DNA Sequencing

- Transport Phenomena: DFT+NEGF

Molecular Electronics / Spintronics : Quantum Computing

Metals, CNT, Graphene: (Nature)

Electrodes: Graphene to replace ITO (Nature Nanotech.)

Super Magneto Resistance (SMR) in GNR: (Nature Nanotech.)

- Nano-optics: nanolens: (Nature)

Near field focusing and magnification beyond diffraction limit thru nanolens

Superfunctional Materials/Devices

Functional nano-materials

Material characterization

Correlation spectroscopy

Chemical/Bio-functional systems

Molecular architectures

•Single electron/photon molecular devices

•Electronics & Mechanics

•Molecular & quantum computing

•Biosensors, biochips, DNA sequencing

•Enzyme Mimetics

•Bioinformatics

Nano-devices

- Self-assembled materials & Self-engineered devices

- Extended supramolecular chemistry

Host-guest interactions: Guests include electron/photon/proton

- Quantum phenomenon driven nano-materials/devices

Computer-aided

molecular design

approach

Research StrategyNanorecognition

Self-assembly,

Self-synthesis

Synthesis of

Building Blocks

Characterization

(structure,

properties)

MotivationSynthesis of Nanomaterials

Unusual electrochemical/photochemical properties

[Quantum properties <= CAMD]

Novel Nanostructures

Design of Nanodevices and NanosensorsSelf-engineered electronics

(Interaction forces: competition vs. cooperation)

Nanomaterials

Nanostructures

Nanodevices

Nanosensors

Design Strategy:

Calculation Methods

Semiempirical, Tight Binding

Density Functional:

Ab initio: MP2, CCSD(T)

Periodic crystal systems:

Atomic and Molecular systems:

PW-DFT

MC

MD

CP-MD, ab initio MD

Excited state ab initio MD

Free energy Perturbation

Simulations:

Theor. Interpretation

Prediction & Design

Quantum Devices – NT

Nonequilibrium

Quantum Electrodynamics

Nanowires, PRL

Nanotubes, JACS

Fullerenes, PRL

Nonlinear optical & Chiral Switches

Nano-electronic/spintronic Devices Nanomechanical Devices Medical Sensors

(Achievements)Functional Molecules,

Materials, Sensors, Devices

hn1 hn2

Moleculae electronics, PRL

Acc. Chem. Res.

+2e-

l1l2

PNAS

JCP

JPCJACS

JACS

Org.Lett.

Angew

Chem PNAS

Molecular Interactions: Chem. Rev.

Science

Chem. Soc. Rev.

Nature

Nature Nanotech

Angew

Chem

PRB

Nature

Dynamical motion of electron charge density

in water for every 10 fs

Electron Carriers

Electron tweezers J. Am. Chem. Soc. 1998

Tuning Molecular Orbitals in Molecular Electronics/Spintronics

Spintronics

Spintronics: Spin + Electronics

utilizing electron spin for electronic devices

Key Features in Spintronics

Spin has long coherence or relaxation time (non-volatile)

Controlling spin requires much less energy than charges.

Spin has the information of phase (quantum coherence).

Spin Valve Devices

Applications

Hard Disk Drive

Giant MagnetoResistance

(Fert & Grünberg)

(Nobel Prize: 2007)

Magnetic Random Access Memory

Tunneling MagnetoResistance

F I F

Tunneling MagnetoResistance

Electron with spin moves through the insulator by tunneling.

Parallel Anti-parallel

F I F

Structure of

Magnetic Junction

Non-magnetic metal

Insulator

Semiconductor

Superconductor

F

Spacer

F

Non-magnetic metal (GMR): HDD Head Insulator (TMR): MRAM

Parallel

smallresistance

AParallel

large

resistance

Magnetoresistance

Difference in resistance between

parallel (P) and anti-parallel (AP)

magnetoresistance ratio:

To become an ideal spin valve,

the MR ratio should be infinte.

AP P P AP

P AP

R R I IMR

R I

The MR ratio for TMR is

larger than that for GMR.

F/Al2O3/F

thickness 1~2 nm

MR 30~70%

Fe/MgO/Fe

MR 220% (CMR)

[Nat. Mater. 3 862 (2004)]

[Nat. Mater. 3 868 (2004)]

CoFeB/MgO/CoFeB

MR 472 % at RT (2006)

MR 804 % at 5K

MR in TMR

GMR: MR 10~20 %

E-field driven Magnetic On/Off Switch

Zero E-Field Non-Magnetic

Non-Zero E-Field Magnetic

6p 10p

Angew Chem Int Ed 46, 7640 (2007)

Density of States

(DOS)

for

3D, 2D, 1D, 0D

Nano Materials

Classical:

L>100nm

Quantum:

L< 10nm

Energy

Energy

Energy

Energy

Den

sit

y o

f S

tate

s

Den

sit

y o

f S

tate

s

Den

sit

y o

f S

tate

s

Den

sit

y o

f S

tate

s

3D 2D

1D 0D

Fe

Co

Ni

Ru

Rh

Pd

Os

Ir

Pt

Magnetism

of

3D, 2D, 1D

Metals

metalicnano-magnets

PW-DFT

scalar-

relativistic

Phys Rev B

69, 193404

(2004)3D 2D 1D

Infinitely long nanowire: intriguing quantum effects: highly unstable

- Only one minimum for

the linear structure of

the CsAu chain.

- Relatively large ratio (~3)

of break force of the CsAu

chain to that of the bulk

CsAu crystal.

Linearization of Au nanowire by Cs-Doping:

Tetramer for pure metal

Tetramer for alloy

Phys. Rev. Lett. 98, 076101 (2007)

0.9 a.u. for CsAu

Electrostatic force

2D 1D

2D

1D

Fractional Quantum Conductance in the Thinning Process

Conductance

4/3 : ~ 4.2 Go

4/1 : ~ 3.5 Go

2/2 : ~2.7 Go

2/1 : ~2.6 Go

Peaks in Exp: 2.4, 4 Go

5/4 x 4 4/3 x 3 2/2 x 3

Electrode effects : fractionally quantized G value

Length dependence for G values : not significant

4/3x35/4x4 4/3x3 2/2x3 5/4x4

Phys. Rev. Lett. 96, 096104 (2006)

1

r r r

L RG E ES H

Basis Set : DZ

Functional : GGA-PBE

Mesh Cutoff : 400 Ry

Geometry Optimization : 0.04 eV/Å

Spin-polarized NEGF Calculations

L S R

2.46 nm

1.7

8nm

†, Im , , Im , ,r r r r

b L b b R b bT E V Tr E V G E V E V G E V

( , ) ( , ) ( , )b b L b R b

eI V T E V f E V f E V dE

h

K-points sampling,

Finite Bias,

Spin Polarized Calculation

Non-collinear Calculation

Parallel Calculation

GGA & LDADFT :

Calculation: Electron and Spin transport: POSTRANS 0.6

†

2

iA E G E G E

p

Electrical currents and Transmission

Electrical currents are determined by transmission probability

Keldysh Nonequilibrium Green’s function method:

Non-interacting electron approximation

( ) ( )r a

L RT E Tr E G E E G E

2

( ) ( ) ( )L R

eI T f f d

h

Landuer-Büttiker formalism

Self-Energy: Renormalization

Level shiftL/R L/R = Re( )

L/R L/R = Im( ) Level broadening

eff L RH H

Chem. Soc. Rev. (2009)

0

0

L L LC

eff

CL CC CR

RC R R

h V

H V H V

V hM M

Screening effect !!

Self-energy

†

†

0 0 0

0 0

0 0

0 0

0 0 0

L L

L L LC

CL CC CR

RC R R

R R

h v

v h V

H V H V

V h v

v h

Set-up of Calculation : Quasi Stationary State

HLL HLL HLLHRRHMM HRRHRRB B

Finite Bias Effect: Hartree Potential

Natural Boundary Condition

2 ( ) 4 ( )eff

scfV r rp ,

,

( ) ( ), 0

( ), 0

( ) ( ),

eff eff

M L bulk

eff eff

M

eff eff

M R bulk

V r V r z

V V r z L

V r V r z L

L RB B

HL HR

HL+Vb/2

HR–Vb/2

( ) ( )effV r r a r b

1( )

2

zr V

L

Contour Integration

Total ~40

contour points

Very efficient !!!

n n nNcontourCG z f z dz G z f z w

EInc_CC 0.5eV

1

2n

B kC

k

G E f E dE G z f z dz ik T G z p

Self-consistent Electron Density

1

L RG ES H

1

ImDM G E f E dEp

( )init r

[ ( )] [ ( )]scf scfH T r V r

( ) ( )i i iH r r

( ) ( )init scfr r

( )final r

NO

YES

,

( ) ( ) ( )scf r D r rn n n

2 ( ) 4 ( )eff

scfV r rp

W. Y. Kim & K. S. Kim, J. Comput. Chem. 29, 1073 (2008).

Non-collinear Spin Calculations

1

Im rG E f E dE p

1

r rr

r r

r r

r

r

G E G EG E

G E G E

GE H

ES

H HH

H H

0

0

SS

S

r r

r

r r

E EE

E E

z

Parallel Calculation:

Most time-consuming steps

Density matrix

1

L RG E ES H

Ncontour

1Im n n nNcontour

DM G z f z wp

, , , , ,R A

L RT E V Tr E V G E V E V G E V

2

( , ) ( ) ( )n L n L R n R nNtrans

eI T E V f E f E w

h

Ntrans

Currents

Parallelization: Almost linear performance

Inversion of Green’s function: ~ O(N3): 99% of the total cpu times

0.0 0.2 0.4 0.60

2

4

6

8

10

cpu

times

(h)

1/ncpus

POSTRANS

SpinKpoints-

samplingBias Parallel

Non-

collinear

Y Y Y Y Y

POSTECH TRANSPORT CODE

J. Comput. Chem.

29, 1073 (2008).

Carbon-based materials for Electronics/Spintronics

Properties…Weak Spin-Orbit Interaction

Spin-orbit (SO) interaction is proportional to Z4.

Organic atoms have weak SO interaction.

Properties…Weak Hyperfine Interaction

For carbon atoms, the most abundant isotopic

form,12C, has no nuclear spin. I = 0

Advantages of Carbon-based materials in Spintronics

Long spin relaxation length

Top-down vs. Bottom-up approaches

Nanomaterials

Top-down

Bottom-up

limitations

1. H-bonding

2. p-p interaction

3. p- H2O interaction

4. Cation-p interaction

H

O

H

H O

H

H

OH

H

O

H

Ag+

Chem. Rev. 100, 4145 (2000)

H

Interactions Forces for Atomic Molecular Assembly(Ionic, Covalent, and Metallic Bondings)

* Noncovalent Bonding for Molelcular Assembly*

~2

~5 kcal/mol

~1 ~2

~30 kcal/mol

~2 ~2

Self Assembly of Calix[4]hydroquinone

Without water

Hexamer OctamerTetramerTrimerDimer

With water

Polymer

8.610.2

47.221.637.439.744.2

11.021.68.8

Binding energy (kcal/mol)

B3LYP/6-31G*

Self-Assembled Arrays of

Calix[4]hydroquinone (CHQ)

Nanotubes

ox.

red.OHO

O

OH

O OH

O

OH

HH

HH

OO

O

O

O O

O

O

top view side view

Science 294, 348 (2001)

J. Am. Chem. Soc. 123, 10747 (2001)

electro/photo-chemical

Nanorecognition

Competition vs.

Cooperation effects

Self-Assembled

NanolensJ. Y. Lee et al. Nature 460, 498 (2009)

Hyper-Refraction:

Beyond Diffraction Limit Near-Field Focusing

and Magnification

H

F

D

R

LSA365

nm UV

1

mm

FDHDRay-tracing

Nano-Micro Tech:

advanced functionalization, minuaturization, high density packing

Top-down approach Bottom-up approach (Fly’s eye)

Thermal reflowFabrications of lenses

Lens grinding/polishing

Self-assembled CHQ nanostructures

Nanolens: CHQ plano-spherical convex lens

-0.5 0.0 0.50.2

0.4

0.6

0.8

D = 1.610 m

H = 0.590 m

R = 0.844 m

Perfect Sphere LENS

Z (

m

)

X (m)

CHQ crystal

1) nucleation 2) 2D growth 3) 3D growth

CHQ lensfractures

film

crystal

film

4) separation

b

1 m 1 m 1 m1 m

d

1 m

c e

l l'

500nm

CHQ film

200 nm 100 nm 100 nm

100 nm

a

2 m

Thermodynamical Analysis :

growth mechanism of

CHQ nanospheres

a

~400nm

250nm30° tilted

Face-up

250nm

~470nmb

30° tilted

Face-down

1m

1m

2m

2m

c~380nm

1m

1m

220nm

Super-resolution of CHQ nanolens (below ½ wavelength)

beyond diffraction limit

Far-fieldOptical Microscope Images

SEM Images

H

F

D

R

LSA

365 nm UV

1 mm

FDHD

Ray-tracing

Finite Difference Time Domain simulations using Maxwell equations

for the optical path of a nanolens

Near–Field Focusing & Magnification

Beyond Diffraction Limit Through a Nanolens

Naturex (µm)

y (

µm

)

x (µm)h=300 nm h=400 nmx (µm)

FDTD simulations - Examples

∆z = -1.5 λ ∆z = -1.0 λ ∆z = -0.5 λ

∆z = 0.5 λ∆z = 0 ∆z = 1.0 λ

• FDTD used to calculate intensity along the POI

at different relative positions of the objective lens (∆z)

• Resolution is estimated from the FWHM of the POI intensity maximum

NA = 0.9

Numerical Scheme

nSIL Resolution – Comparison with SIL

SIL (same objective)

(NA = 1.44)

Max res. SIL

(n = 1.6)

Regions where

nSIL beats SIL

Improvements

Face Down ≈ 25%

Face Up ≈ 35%

Opt. Lett. 35, 2007 (2010)

Applications of Nanolens:

UV lithography using a nanoscale lens

Photochemical imaging through the CHQ lenses.

a, A FDTD simulation image (|Ex|2) of the lens on resist polymer layers.

b, SEM images of developed patterns after irradiating 365nm UV light through the

nanolenses, UV exposure time: 1s for t=0 -500nm, 4s for t>2μm.

c, FDTD simulation images corresponding to b.

d, |Ex|2 corresponding to a, showing sharp peaks at F=500~600 nm.

Magnetic phase transition

M+&C60

Change of spin state

Exohedral

fullerenes

X@C60,

X=N, P, As, O, S

Phys. Rev. Lett.84, 2425 (2000)

C

C C

C C

H H

H

CC

CC

HH

HH

CC

CC

HH

H

CC

C

HH

C

C

CC

CC

C C

HH

C C

CC

H H

CC

CC

HH

CC

CC

HH

CC

CC

HH

CC

CC

HH

C

CC

HH

C

HH

Trannulene

Cyclacene: side view

Cyclacene:

perspective view

Angew. Chem.

Int. Ed.

38, 2256, (1999)

smallest carbon nanotube

Endo/Exo-hedral Fullerenes,

Nanotubes, and Nano-tori

Qubits

Qubits

Ultralong

thinnest

SWNT

d=0.4 nm

PNAS 102, 14155 (2005)

JACS 127, 15336 (2005)

Si

+ + + +- - - - -

Electron transfers

20 nm

Endohedral spins of N@C60; P@C60 for Quantum Computing

(Qubits)

outer tubes

furnace

turbulent flow

laminar flow

inner tube

flow in flow out

substrate

a

b

JACS 127, 15336 (2005)

PNAS 102, 14155 (2005)

ultralong thinnest SWNT

d=0.4 nm

Graphene

Properties…Mechanically

Flexible

Stable at high temperature (3000 oC)

like diamond or CNT

Properties…Electronically

High carrier mobilities over 15,000 cm2V-1S-1

Ballistic transport in submicrometer scale

(0.3 mm) at 300K [Nature Mater. 6, 183 (2007)]

Properties…Magnetically

Long spin relaxation length: 1.5 ~ 2 mm at 300K

due to weak SO and hyperfine interactions [Nature 448, 571 (2007)]

A.K. Geim, K.S. Novoselov, Science 2004/ 2007/2008, Nature 2005.

P. Kim, Nature 2005, Science 2007. K.S. Kim, … B.H. Hong, Nature 2009.

Magnetoresistance

Magnetoresistance (MR) = 114 (%) over the whole Vb range

Vb (Volt)

Synthesis, etching and transferring processes of the large-scale and patterned graphene films. a, Synthesis of patterned graphene films on thin Ni layers. b, Etching by FeCl3 (or acids) and transfer of floating graphene films. c, Etching by HF (or buffered oxide etchant) and transfer of graphene films by a PDMS stamp.

Large-scale Stretchable Graphene

Nature 457, 706-710 (2009).

http://www.nytimes.com/2009/01/20/science/20obbend.html?_r=1OBSERVATORY

With an Ultrathin Film, a Big Step Forward for Flexible Electronics

By HENRY FOUNTAIN

Published: January 19, 2009

Flexible electronics — the kind that might be used in “smart” clothing,

say, or in foldable displays that could make reading news online more

like reading it in print — are still far from an everyday reality. But

scientists in South Korea are reporting a significant advance toward the

development of such devices.

Stretchable graphene electrode patterns transferred onto a silicon-based polymer.

Web Link

Large-scale Pattern Growth of Graphene Films for Stretchable Transparent Electrodes

(Nature)RSS FeedGet Science News From The New York Times »

K. S. Kim, Y. Zhao, H. Jang, S. Y. Lee, J. M. Kim, K. S. Kim,

J.-H. Ahn, P. Kim, J.-Y. Choi, and B. H. Hong,

Large-scale pattern growth of graphene films for

stretchable transparent electrodes,

Nature 457, 706-710 (2009).

Enhancement of micro-Raman intensity

by a CHQ nanolens on graphene

G2D

Relocation of

CHQ nanolenses

for fabrication

FIB-SEM/SIM-images

Dual FIB technique

Nanolens Array

OM image

SEM image

Molecular Electronics with CNT Electrodes

R

L

dEEfEfVETh

eVI RL

,

2 2Non-equilibrium Green’s function method

(Implementation on SIESTA code based on LCAO DFT)

DFT functional: LDA-Perdue-Zunger

SZP basis-setsLandauer-Büttiker formula for I-V characteristics

PE: phenyl ethynyl

PP: pyrrollo pyrrole

Molecular-wire /

CNT-electrodes

C2C1 C3 C4 C5 C6 C7 C8 C9 C10

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10

-0.020

-0.015

-0.010

-0.005

0.000

0.6 V

1.5 V

2.4 V

(C)

0.0 0.6 1.2 1.8 2.4-0.2

-0.1

0.0

e

Vb (V)

e

Atomic indices

Asymmetric Potential Drop at 2.4 V due to the change of molecular chargeScreening of the external bias voltage => change of the charge distribution

High bias voltage : no more screening - change of molecular charge - change of the local potential- asymmetric potential drop

Negative Differential Resistance

Phys. Rev. B 76, 033425 (2007)

0.0 0.6 1.2 1.8 2.4

0

1

2

-400 0 400

-10

-5

0

5

10

Vb(mV)

I(V

) (

nA)

I(V

) (

A

)

Vb(V)

PE

PP

Metals (Au : Ru)

-Hollow site on (111) surface

CNT

-covalent bond to C

Linker

-S or direct contact

Core molecule

-C6 or benzene

Calculation detail

-POSTRANS(SIESTA+NEGF)

-PBE

-150 Ry

-TM pseudopotential

Effect of electrodes

on electronic transport

Au

Ru

CNT/

Graphene

Transmission

0

1

2

Au

Ru

CNT

0

1

2

0

1

2

0

1

2

Tra

nsm

issio

n

(a) with S (b) without S (c) C6 --> benzene

0.0

0.5

1.0

0.0

0.5

1.0

-2 0 20.0

0.5

1.0

-2 0 20.0

0.5

1.0

E-Ef[eV]

-2 0 20.0

0.5

1.0

Extents of broadening and alignment of a peak are of an electrode origin.

Linker dependence

molecule dependence

s-band

p-band

Tra

ns

mis

sio

n

d-band

Au

Ru

CNT

I - V curve

0.0 0.5 1.0 1.5 2.00

10

20

30

Cu

rren

t (

A)

Voltage (V)

0

1

2

3

4

5

CNT-amide

Au

CNT-S

Higher for metals, smaller for CNT

(large coupling limit)

CNT can offer I-V curve non-linearity that is of an electrode origin

Electrodes are not a deterministic factor.

but a useful factor contributing to molecular transport properties.

Conductance

Non-linearity

Caveat

Y. Cho. et al.

J. Phys. Chem. A

113, 4100 (2009).

Creation of the Domain Wall

0 5 10 15 20 25 30 35-8

0

8

16

24

32

40

48

ED

W (m

eV)

WDW

(nm)

B = 0 mT

B = 30 mT

Energy required to create a magnetic domain wall

(EDW)

Spin direction: out of plane

due to the dipole interaction

Edipole > 30 x Eso

WDW = 10 ~ 15 nm

If B ≥ 30 mT, a DW is created.

ㅊ Nature Nanotech. 3, 408 (2008)

SMR: Super Magnetoresistance

The unique band symmetry of GNRs gives

unrivalled MR and highly spin-polarized currents.

Mis-matching in orbital symmetry as well as spin symmetry

leads to the striking enhancement in MR. (super-MR: SMR)

*(giant) GMR: FM-NM-FM, *(collosal) CMR: FM-MgO-FM,

*(tunnel) TMR: FM-Insulator-FM, *(super) SMR: FM-(FM)-FM

Nature Nanotech. 3, 408 (2008)

P

case

AP

case

Parallel Anti-Parallel

Super-MagnetoResistanceAP P

P

R RMR

R

300K:Exponential dependence

Width dependence

8-ZGNR (1.79 nm): ~106 %

32-ZGNR (6.97 nm): ~104 %

5K:

Almost constant

No width dependence

N-ZGNR : ~106-107 %

8-ZGNR

16-

24-

32-

Only α-spin contributes to currents Spin-polarized currents

I-V Characteristics in Zigzag Graphene Nanoribbon

( , ) ( , ) ( , )b b L b R b

eI V T E V f E V f E V dE

h

b

b

dI VG

dV

1R

G

Current, Conductance, and Resistance

RP : The slope shows quantum conductance (Go = 2e2/h = 77.48 S)

due to the perfect transmissions

RAP: Huge resistance due to the zero transmission gap

αβ

αβ

fL-R 5K

300K Vb = 0.09V

Vb=0.15 V

W. Y. Kim & K. S. Kim, Nature Nanotech. 3, 408 (2008)

Spin-valve device based on GNR: Utilization of the edge spin states

Parallel

Anti-Parallel

W. Y. Kim & K. S. Kim, Nature Nanotech. 3, 408 (2008)

AP: AP:

P:P:

SMR GMR/TMRSMR

A novel graphene analogue

Modification:

Defects: Red circles

N doping : Blue circles

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

N

NN

N

N

Physical properties

Aromaticity is retained

Non-bonding Radicals

A novel graphene analogue

Ultra-Soft Pseudo potential

GGA (PW86) Functionals

7×7 k-point grid

-5

-3

-2

0

2

3

5

K

E-E

F

(eV

) Majority spin

Minority spin

M

Half-metallic band structure Density of states

-2 -1 0 1 2

0

1

2

3

Tra

nsm

issi

on

E-EF (eV)

Majority

Minority

Spin

density

Design & Synthesis of ion receptors & ion sensors

Immense potentials in biological & environmental processesSalts from Sea water; Poisonous materials from water & soils;

Radioactive materials from Nuclear wastes; Drug delivery; Nanotech

FˉClˉ

Chem. Soc. Rev.35, 355 (2006)

Angew. Chem.44, 2899 (2005)

JACS126,8892(2004)

0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 -1.6 -1.8 -2.0

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

Curr

ent density(m

A/c

m2)

Voltage(V)

S

S

H

-O

O-

S

S

O

O

H

Cyclic Voltammogram

1

S S

S S

H H

H

NH2

H

H H

H

NH2O2N

H

O2N

hv 'hv

Sensor

Molecular electronic sensor.

The ON and OFF states would show

different I-V characteristics.

- <bio-nano-devices>

Nanomechanical Device:

Conformation Change by Redox Process

Photo Switch

Molecular Sensing

DNA Sequencing

Molecular Flipper/Robot

New ChemistryNew functional molecules, new chemical systems, molecular clusters, molecular wires, metal wires, 1D/2D molecular systems, hydrogen storage

Novel inophores/receptors (new class of organic molecular systems)

Enzyme mechanisms, Bio-macromolecules, Polymers, Condensed phase

Novel self assembly techniques: self-synthesis

Synthesis of organic nanotubes, nanowires, nanoparticles, nanostructures

Synthesis of ultralong ultrathinest single wall nanotubes

Synthesis of ultra-wide single-layer graphene

Synthesis of nanscale lens with ideal spherical shape through self-assembling

New PhysicsMolecular electronics/spintronics: Super-magnetoresistanceNanoscale lens comparable to wavelength: distinctive optical phenomena :

New nano-optical phenomena: Super-refractionnear-field focusing and magnification (curvilinear beam trajectory)super resolution beyond diffraction limit

Enhancing optical signal for analysis

Improving photolithographic techniques for nanodevices

Optical memory storage, optical nano-sensing, etc

Summary

Acknowledgments:Dr. Woo Youn Kim, Dr. Young Cheol Choi,

Seung Kyu Min, Yeonchoo Cho,

Dr. Daniel R. Mason Dr. Ju Young Lee,

Prof. N. J. Singh Prof. In-Chul Hwang

Prof. Han Myoung Lee and many others …

Prof. Byung Hee Hong (Sungkyunkwan U)

Prof. Philip Kim (Columbia U)