Nanoscience and Organic Electronics

Dr. Dilip Kumar Maiti, FRSC

Professor
Department of Chemistry
University of Calcutta
Gate Drain
Source
Organic Nanowire

Metal for Source and

Drain
SiO2
Si substrate
Electrical isolation

Gate contact
1
Gold Nanoparticles FFFabrication of Mn(VI)-NPs Organic Nanobelts Organic FET Device

Development of Nanotechnology

2
 Environment: Paint That Cleans Air
Buildings as air purifiers?

• Nanopaint on buildings could reduce pollution

– When exposed to ultraviolet light, titanium dioxide (TiO2)
nanoparticles in paint break down organic and inorganic
pollutants that wash off in the rain
3
– Decompose air pollution particles like formaldehyde

Materials: Paint That Doesn’t Chip

Mercedes covered with tougher, shinier nanopaint

• Protective nanopaint for cars

– Water and dirt repellent
– Resistant to chipping and scratches
– Brighter colors, enhanced gloss
– In the future, could change color and self-repair? 4
Health Care: Detecting Diseases Earlier

• Quantum dots glow in UV light

– Injected in mice, collect in tumors
– Could locate as few as 10 to 100 cancer cells

Quantum Dots: Nanometer-sized crystals

that contain free electrons and emit
photons when submitted to UV light
Early tumor detection,
5
studied in mice

How Might Nanoscience and

Nanotechnology improve our lives?
• Materials: Stain-resistant Clothes, Paints, Coating …….
• Health Care: Biological sensors, drugs, drug delivery
devices…………
• Technology: Better data storage, computation,
Semiconductor, Field Effect Transistor, Switch,
Optoelectronic, Photovoltaic and other Nanodevices
• Environment: Clean energy, clean air…………

Thin layers of gold are used Carbon nanotubes can be Possible entry point for
6
in tiny medical devices used for H fuel storage nanomedical device
 Nanodevice: Nano Solar Cells
• Nano solar cells mixed in plastic could be
painted on buses, roofs, clothing
– Solar becomes a cheap energy alternative!

] 200 nm

Nano solar cell: Organic nanorods embedded in semiconducting polymer,

sandwiched between two electrodes
7

Technology: A DVD That Could Hold a

Million Movies

• Current CD and DVD media have storage scale

in micrometers
• New nanomedia (made when organic
compound self-assembles into strips on
silicon) has a storage scale in nanometers
• That is 1,000 times more storage along each
dimension (length, width)…

…or 1,000,000 times greater

storage density in total!

8
 Health Care: Nerve Tissue Talking to
Computers
• Neuro-electronic networks interface nerve cells
with semiconductors
– Possible applications in brain research,
neurocomputation, prosthetics, biosensors

9
Snail neuron grown on a chip that records the neuron’s activity

Nanoscience and Nanotechnology: An Overview

The word nano is from the Greek

word ‘Nanos’ meaning Dwarf. It is a
prefix used to describe "one billionth"
of something, or 0.000000001.

It’s not just Chemistry, physics,

Biology, Material Science,
Electronics, and Engineering. It’s all
sciences and technologies those
work with the very small.

Nanobots, Nanowires, Nanobelts…

10
Excerpt from Letter of Benjamin Franklin to William Brownrigg (Nov. 7, 1773)
...At length being at Clapham, where there is, on the Common, a large Pond
... I fetched out a Cruet of Oil, and dropt a little of it on the Water. I saw it
spread itself with surprising Swiftness upon the Surface ... the Oil tho' not
more than a Tea Spoonful ... which spread amazingly, and extended itself
gradually till it reached the Lee Side, making all that Quarter of the Pond,
perhaps half an Acre, as smooth as a Looking Glass....

Richard Feynman’s
vision: “There is
Plenty of room at
the bottom…” in
1959 (APC meeting)

Understanding Size
How small are nanostructures?

Single Hair

Width = 0.1 mm
= 100 micrometers
= 100,000 nanometers !

1 nanometer = one billionth (10-9) meter

 Smaller still

6,000 nanometers DNA

Hair

.
Red blood cell

3 nanometer

Nanoscience Defined
Nanoscience is the name given to the wide range of interdisciplinary science that is
exploring the special phenomena that occur when objects are of a size between 1 and
100 (<1000) nanometers in at least one dimension. This work is on the cutting edge of
scientific research and is expanding the limits of our collective scientific knowledge.

Scanning Electron Microscope (SEM),

Transmission Electron Microscope (TEM),
Traditional chemistry and physics concepts
may not be applicable at the nanoscale level..
Atomic Force Microscope (AFM),
Scanning Tunneling Microscope (STM)
 Nano is Different
• At the micron (1,000 nm)
and larger scale, classical
physics determines
properties.

• At the Angstrom (0.1 nm)

scale, quantum mechanics
determines properties.

• At the nanometer scale,

fundamental properties
depend on exactly how big
the particle is.

Size Matters

Nanogold colors

But where are the new phenomena?

–Optical (e.g. color, transparency)
–Electrical (e.g. conductivity)
–Magnetic Properties (e.g. magnetic moment)
–Physical (e.g. hardness, melting point)
–Chemical (e.g. reactivity, reaction rates)

Quantum Size Effect & Surface Atom Effect

 Physical Properties
O
BnO
N
BnO
OBn N

3b
H
O
O

Nanobelt (< 50 nm)

Nanobuilding block

Properties of the nanoparticles can be explained by

Quantum Size Effect

&
Surface atom Effect 17

Size-dependent Optical Properties

Quantum confinement

Increasing size of the Silver nanoparticles

18
 Size-Dependent Optical Properties

Electric Properties: Quantum confinement effects in

materials with delocalized electron states

LUMO
LUS

HOS Thermal energy

HOMO

3 nm (Au, Ag, Pd, Pt…Semiconductor)

20
 Types of Materials

21

Catalysis
• Surface Atom Effect:
- Nanoparticles have increased total
surface area
- Have increased total number of atoms
accessible in the surface
- Increased catalytic activity of those
atoms
- Tunable surface catalytic properties by
changing in shape, size and
compositions
- Easy recovery of the solid nanocatalyst
22
 Dispersion: Surface Atom Effect

N=8
F=1
N=216
N=64 N=125
N=27 F=0.704
F=0.875 F=0.784
F=0.963

F=6n2-12n+8/n3
F=6/n

23

Low Coordination Number Plays the

Vital Role in Catalysis

24
 Fabrication of Metal Nanoparticles and Their Properties
Ways to the Nano World Top-down approach
Methods:
Top-down approach
&
Bottom up approach

Ball-mill grinding

25

Bottom Up Approach to Nanomaterials

Bottom-up
Nucleation processes approach

Decomposition
surface
(CdCO3 +Na2S)

Nucleation
(CdS)

volume Total

Growth
(CdS)

Quenching
26
Nanoreactor built-in Water
1. We always look for reactions
which should be operationally
simple, benign in nature, fast
reaction convergence,
outstanding chemo-, regio-,
diastereo- and
enantioselectivity, and
excellent yield.
2. Surprisingly all chemical
transformations in Nature are
of this type and water is
inevitable for these reactions.
Cascade reaction, reaction
control, fine tuning of the
product, use of outcome of
one reaction as substrate of a
next reaction, stabilization of
transition states and reagents
are performed by nature
through construction of well-
defined reaction environment.
The supramolecular
assemblies like micelles,
emulsion and vesicles of
nanometer dimension are the
well defined reaction
environments built in water
medium for chemical
conversion in cell. As you can
see the similar hydrophobic
environment is made by cell
membrane using lipid
molecules to protect our cell
content.
3. These outstanding properties
of water are due to its unique
structure, both acidic (H3O+)
and basic (HO) nature, strong
hydrogen bonding, high
polarity, dielectric constant,
surface tension and heat 27
capacity.

Driving Force for Micelle Formation Micellar Kinetics

Forces driving micelle formation:
Micelles are NOT static structures.
(a) hydrophobic force
(b) entropy
Micelles are unstable structures
with two characteristic relaxation
Forces opposing micelle formation: times – fast relaxation time (τ1) and
(a) charge repulsion between slow relaxation time (τ2)
ionic polar heads
(b) concentration gradient
(c) thermal (Brownian) motion Insertion of Organic Compounds


+
Fast relaxation time, microseconds
Water medium

+ +


Slow relaxation time, milliseconds to minutes

28
 Packing Directed Self-Assembly
Chem. Rev. 2005, 105, 1401

29
Surface packing parameter
29

Fabrication of Metal Nanoparticles

1. Cooperative self-assembly (Low valent metal NPs)
Formation of Decomposition Removal of
template
assembly Nucleation
Growth
Quenching Metal NP
Amphiphile or stabilizer
Cooperative Template surrounded
Precursors Self-assembly metal NPs

2. Creation of nanospace (High valent NPs)

Decomposition Removal of
Precursors Nucleation template
Growth
Quenching Metal NP

Created Created nanospace Template surrounded

nanospace with precursors metal NPs

30
Fabrication of Cu(0)-NPs for Organic Transformation in Water
Fabrication of Cu(0)-NPs and Scope Water surrounding Cu(0)-NP

ed
1. Although, Wohler’s use of water as a
Reduction,
ound er
Nucleation, rr lay
medium for the synthesis of urea has been Reverse micelle- Growth, and Su anic
CuSO4.5H2Olike aggregation org
known for many years, scientists of Quenching
(Precursor) of the ingredients
academic and industrial settings are now + H 2O ( )
exploring the possibility of replacing large
volumes of toxic organic solvents by water
as the reaction medium toward the R1
SDS CO2R2
development of cleaner and green (Amphiphile)
NO O OH
processes. + Reductive organic R1 CO2R2
transformation
Hemisphere of the
or
OH
2. Water is the solvent of a magnificent array cooperative assembly (II)
of reactions taking place in our body for Ascorbic acid
R1 O
(Reductant) N
keeping it healthy and functioning. Water is
Ingredients (I) Nanoreactor(III)
inevitable for selective formation of new
bonds during biosynthesis of small 1,3-DC with terminal alkyne Reductive Homoatomic
molecules and multistep synthesis of N-N bond cleavage
macromolecules. Cu-NPs, PhC CH (5) Cu-NPs
N N (In situ generated) XN3 XNH2
(in situ generated)
Ph
3. These outstanding properties of water are N Ascorbic acid, SDS, R1 Ascorbic acid, SDS, R1
X H2O, 60°C 1 (X= CO) H2O, 60°C
due to its unique structure, both acidic 6 (X= SO2) 2 (X= CO)
(H3O+) and basic (HO−) nature, strong R1 3 (X= SO2) 4 (X= SO2)
hydrogen bonding, high polarity, dielectric Not found
constant, surface tension and heat capacity. Reductive Heteroatomic
N-O bond cleavage
4. To avoid toxic organic solvents, highly R3 Cu-NPs O OH
R3 Cu-NPs
reactive metal-NPs can be employed as HO
R4 (in situ generated)
(In situ generated) R2 R4
efficient catalysts for fundamental organic R2 Ascorbic acid, SDS,
R2 Ascorbic acid, SDS, O R3
transformation in a water medium by N H2O, 60°C
O N H2O, 90°C
construction of surfactant assembled 9 (R4=CO2Et) 7 8
nanoreactor. 31
Krishnanka S. Gayen, D. K. Maiti* Green Chemistry 2012, 14, 1589

Characterization of Nanoreactor and Cu(0)-NPs

SEM Image of the Nanoreactor 0.60
0.58

a
0.56
0.54
586 nm
b
Absorbance

0.52
0.50
0.48
0.46
0.44
0.42
400 500 600 700 800
Wavelength (nm)

Size Distribution by Intensity

7.8 e

1 10 100
Size (d.nm)

Figure 1. (a) SEM image of the cooperative assembly, (b) UV-vis spectrum, (c) TEM image, (d) Powder XRD and
(e) DLS data.

32
Benign Reductive Process to Afford Functionalized Primary Amide

Catalytic Activity and Scope

1. Homoatomic reductive-cleavage of the N–N bond in carbonylazide afforded valuable primary amides with fast reaction
rates (1.5–2.0 h) and high yields (79–95%).
2. The performance of our benign method is evaluated by the reduction of carbonyl azides bearing electron donating,
electron withdrawing, halogens and π-bonds to afford functionalized amides with an extremely low catalyst loading
(0.2 mol%).
3. Reductive cleavage of N-N bond is expected by transfer of hydrated electrons from highly active surface of the in situ
fabricated low valent Cu(0)-NPs. 33
Krishnanka S. Gayen, Dilip K. Maiti, Green Chemistry 2012, 14, 1589-1592

Possible Reaction Path of the Unusual Reduction Process

1. The reaction is presumed to proceed via the predominant activation and reductive cleavage of the heteroatomic N–O
bond by electron transfer from the highly active surface of the Cu(0)-NPs involving water clusters to form a stable Cu+2-
chelated six membered intermediate IV.

2. It is on protonation and subsequent Cu+2-assisted removal of ammonia (V), provides 2 (path a).

3. On the other hand, intermediate IV at a higher temperature (80 °C) is expected to undergo domino cyclization involving
the C=O group of the ester functionality to form a seven-membered intermediate, VI.

4. Intermediate VI is subsequently transformed into γ-hydroxy pyrrolinone (3, path b) via the formation of a putative five-
membered cyclic intermediate VII.
34
5. The Cu(0)-NPs are regenerated from Cu+2, which involves the construction of the nanoreactor (III).
Design and Synthesis of Functionalized MnVI-NPs

35

Me3SiOMnO2Br

36
 Fabricated high-valent Mn(VI)-NPs and EELS study

37

EELS Images of the Individual Components Present in Me3SiOMnO2Br-NPs

38
Hyperfine Electron Spin Resonance Spectra and Unusual Magnetic Moment

Magnetic moment for

d1-Mn(VI): 1.7 BM
Observed: 2.2 BM

39
39

Squid measurement and alignment of the tiny magnetic nanoparticles

40
Direct Synthesis of Flavones Through O-C/N-C & C-C Coupling.

41

Direct Synthesis of Azaflavones, Thioflavones and enal synthons.

42
Catalytic Cycle for Synthesis of Flavones and Enals

1-3

4 _
NPs- Br

NPs- (3)
NPs-
I
Et3N
6-8
+
Et3NH
_
Br
NPs-

II

Mn VI-N Ps
VI O R5
O Mn R5 O
C H 2O H CH O M nVI [O ]
CH O CH 2OH
M nVI-Br-N Ps O O O
+ Mn IV-N Ps
9 (4)
OH + R 5-C HO (1) Ar H H
Ar
Ar Et 3N
1a 5
Reaction condition: BrMe 3 SiOMnO2 (10 mol%), NaIO 4 (1.1 mmol), THF, Et 3 N, ref lux
43

XPS Spectra of the Fabricated Mn-NPs (i) and

Recovered NPs from the Reaction Mixture (ii)

44
 Nanotechnology: Solar Cell with Pentacene Nanomaterials

Ejection of two electron by one incident photon

Ejects two electrons per photon and thus

Making solar cell powerful.
46% of the incident photon is effective
to produce current.
43% more sensitivity than the theoretical value.

45

Organic Electronics and Their Prospect

(1) Organic electronics is a branch of electronics that deals
with conductive organic compounds which are carbon based.

(2) Inorganic electronics, on the other hand, relies on inorganic

conductors or semiconductors like copper or silicon.

(3) For the past five decades, inorganic semiconductors (Si, Ga,
As) and metal conductor (Cu, Al) have been the backbone of
the electronic industry.

(4) Innovative organic materials play a vital role toward

outstanding improvement of semiconducting, conducting,
photoluminescence, storage and display performances.

(5) Organic electronic products are lighter, more flexible and

less expensive than their inorganic counterparts.

(6) Organic materials are non-magnetic.

(7) Electronic and optical property can easily be tuned by

structure modification which is not possible in silicon
electronics.

(8) This opens up the door to many exciting and advanced new
applications that would be impossible using copper or silicon.

(9) These are also biodegradable (being made from carbon). 46

 Aggregated Organic Nanomaterials for Organic Electronics
1. Fabrication of low molecular mass
organic materials (nanobelt,
nanotube, nanofibril, nanoware etc.)
can be achieved by utilizing
noncovalent intermolecular forces (p
p stacking, hydrogen bonding,
charge transfer, and van der Waals
attraction operating between the nano
building blocks.
H-Aggregation: Face-to-face binding; p-Delocalization
O
BnO H O

through cofacial organic nanostructured material

N
BnO

2. In H-aggregates organic building

OBn N
O

blocks are self-assembled in “face to Building block

face” type of arrangement . (Heterocyclic scaffold)

3. In J-aggregates organic building J-Aggregation: End-to-end binding

Electrostatic gluing interaction guided generation of one
blocks are self-assembled in “end to dimensional organic nanostructured material
end” type of arrangement .

4. Chromophore in the H-aggregates

show blue shift where as J-aggregates
show red shift.

5. Cofacial organic nanostructured

materials have found outstanding
applications in fabrication of high-tech
devices (organic electronics).

Packing of Organic Nanobuilding Blocks

48
 Noncovalent Weak Interactions Operating between
Nano Building Blocks

2.87 Å

Hydrogen bonding
between o-H and p-Cl O
H
b P. Pandit, D. K. Maiti* Chemical
Me
N Communications 2011, 47, 1285-1287
CO2tBu
2.87 Å N N
Cl Cl
N

Weak interactions
6i

c d

Nanostructured organic material

NO2

N. Chatterjee, D. K. Maiti* Chemical

N N N N
OMe

Communications 2010, 46, 2022-2024 49

N N

O2N

Top view of the molecular stack

Methods for Fabrication of Organic Nanomaterials

Xerogel from
Organogel and
Hydrogel

(1) Reprecipitation approach

(2) Ultrasound assisted generation of organic nanostructured

materials

(3) Gel formation

(4) Micro crystallization

(5) Spin coating

(6) Vapour deposition

(7) Langmuir Blodgett method

50
 51
S. Halder, D. K. Maiti* J. Org. Chem. 2009, 74, 8086-8097

Sugar-Based 1D-Chiral Organic Materials

O
BnO
N
BnO
OBn N

3b
H
O
O

52
 Aggregation Induced Enhanced Emission
O
BnO H O
N
BnO
OBn N

< C3-C4-C8-
O

N9 = +24.6°

DFT optimized structure LMSOM nanobelts

1.0 260 nm 310 nm 385 nm 490 nm 425 nm

LMSOM
0.8 Bulk material 500

Emission Intensity
0.6 400
Absorbance

Monomer LMSOM
300
0.4 415 nm
360 nm
420 nm 200
Monomer
0.2
100

0.0
300 400 500 600 330 360 390 420 450 480
Wavelength(nm) Wavelength(nm) 53
UV spectra S. Halder, D. K. Maiti* J. Org. Chem. 2009, 74, 8086-8097 Fluorescence spectra

Designing Small Molecules for Organic Nanomaterials

54
 Low Molecular Mass Self-Aggregated Organic Nanomaterials

CO2Et
N
Cl
O2N Cl CO2Me
O2N CO2Et
N N
CO2Mee
N
Cl
Cl

Cl CO2Et
N
CO2Et
N
Cl

55
Imaging in a Scanning Electron Microscope P. Pandit, D. K. Maiti* J. Org. Chem. 2009, 74, 2581-2584

O H
Me Ph
O
Me O N Ts
O N

56
DFT Study for Designing Nanobulding Block and Aggregation Pattern

H-Bonding
Dipole-dipole

pp Stacking pp Stacking

Packing Nature Sheet-like aggregated morphology 57

Fabricated Nanomaterials of Phenazine 8 and Mixed 8+SA(1:1)

(a)
O OH
N N
N Me N Me
H
N N
(8)
(I)
HB O
H
O O Me
N H
N
HB 58
N Me
(9)
 Spin Coated Organic Nanomaterials of Phenazines (4)

Fabricated Monolayer by LB Method of Phenazine 4

Phenazine 4 Phenazine 4 + Stearic acid

400nm 200nm

O
Me 4
N
N
3.5
3.5 10
3 H 3

N
2.5
2.5
2
Z[nm]

2
1.5
Z [nm ]

1.5
4
1
1 0.5

0.5 0
0 100 200 300 400 500 600
0
0 200 400 600 800 X[nm]

X[nm]

AFM image of monolayer LB films of (a) pure 4 and (b) mixed with SA at
molefraction X4=0.5 on to silicon substrate along with line analysis spectra.
 I-V Characteristic: Switching Behaviour of 4/4-SA Mixed Films
8
DR374 DR374-SA
V = 1.9 V 8
TH
V = 1.3 V
TH
6
6

ON

Current (mA)
Current (mA)

ON
4 1.9V 1.3V
4

2
2

OFF
OFF
0 0
0 1 2 3 0 1 2 3
Voltage (V) Voltage (V)
61
61

Initially Characterized I-V Pattern of Pure Phenazine 8

20
(a)
15

10

5
Current ( m)

-5

-10

-15

-20
-2 -1 0 1 2 62
Voltage (V)
De Novo Design for Organic Nanoelectronics: High
Resistance State and Low Resistant State

OFF state (HRS) ON state (LRS)

63
ON state (LRS)

Crossbar Memory

Organic Crossbar Memory

O
Me
N
N 10
H
N

64
Crossbar Memory Device

65

66
 67

Out Put of this Study

1. We have designed and synthesized phenazine nanobuilding blocks

2. Fabricated one dimnsional (1D) organic nanomaterials for two

memory application

3. Memory devices for write-once-read-many-times (WORM) types is

suitable application for
(i) Non-editable database

(ii) Archival memory

(iii) electronic voting

(iv) radio frequency identification (RFID)

4. We achieved organic resistive-switching random access memory

(ORRAM) utilizes the switching of resistance states for ultra fast data
storage with highly stable organic nanoelectronics.
68
Semiconductors for Organic Field Effect Transistor
[EtC Mo(NAr(tBu))3]

p-Type Semiconductor:
Arylene ethynylene
macrocycle (AEM)

n-Type Semiconductor:
Tetracarboxylic
diimide (PTCDI)
69
69

Organic Field Effect Transistor (OFET)

(a) Hydroxyl-functionalized tetracene.

Chemical and crystal structures and lattice
(b) Schematic of bonding and orientation parameters of unsubstituted (4T), mono-TMS-
of the functionalized tetracene on substituted (4TTMS), and di-TMS-substituted
aluminum oxide. quaterthiophene (4T2TMS).
Terminal substitution determines the in-plane tilt (d)
(c) Schematic of the self-assembled of the oligothiophene cores, with 4T2TMS (51) > 4T
70
monolayer transistor. (34) > 4TTMS (26).
M. Mas-Torrent and C. Rovira Chem. Rev. 2011, 111, 4833–4856
 Design
Designof
ofOrganic
OrganicField
FieldEffect
EffectTransistor
Transistor(OFET)
(OFET)

71 71
71

Fabrication of Organic Field Effect Transistor (OFET)

Field Effect Transistor (FET) using Organic Nanostructured Materials as a Channel
Methodology (OFET)
Gate Drain 1. Growing SiO2 on
Source Silicon substrate.
Organic Nanowire
2. Patterning the oxide
layer to create grooves
Metal for Source and by Nanolithography.
Drain
SiO2
3. Implementing solution-
processable method for

Si substrate
fabrication of organic
material.
4. Deposition of insulator
Electrical isolation (polymer/SiO2) layer &
polymer/metal gate
Gate contact deposition.
5. Patterning S/D metal
deposition &
Organic nanoware

constructing of S/D
contact.
6. Electrical 72
characterization.
Typical electrical characteristics obtained in a field-effect
transistor. The boundary between linear and saturation regime is
indicated by a grey curve.

73

Organic Light Emitting Diodes (OLED) Structure

using Organic Nanostructured Materials

(ITO-Anode)
p-Type organic material
Metal Emissive material
electrodes
(LiF/Al-Cathode) n-type organic material

Methodology (OLED)
1. Development of heterocyclic scaffold as an emissive material with suitable Donor & Acceptor to
tune the emission wavelength and intensity

2. Fabrication of the organic nanostructured materials by solution-processible method to reduce the

defect and impurity in the emissive layer.

3. Determination of HOMO and LUMO energy of the emitter by DFT calculation (Gaussian software)
and CV measurements.

4. Development of p-Type (hole transporting) and n-type (electron transporting) organic materials
with alignment of the energy level to active material.

5. Installing suitable electrodes with work-function comparable to the HOMO-LUMO energy of p-type,
74
n-type and emissive materials.