lee, charles - organic materials chemistry - spring review 2012
Post on 11-May-2015
926 Views
Preview:
DESCRIPTION
TRANSCRIPT
Integrity Service Excellence
DISTRIBUTION A: Approved for public release; distribution is unlimited
Organic Materials
Chemistry
Charles Lee
Program Manager
AFOSR/RSA
Air Force Research Laboratory
09 MAR 2012
2 DISTRIBUTION A: Approved for public release; distribution is unlimited
2012 AFOSR SPRING REVIEW
NAME: Charles Lee
BRIEF DESCRIPTION OF PORTFOLIO:
To exploit the uniqueness of organic/polymeric materials
technologies for enabling future capabilities currently unavailable by
discovering and improving their unique properties and processing
characteristics
LIST SUB-AREAS IN PORTFOLIO:
Photonic Polymers/Organics
Electronic Polymers/Organics
Novel Properties Polymers/Organics
NanoTechnology
3 DISTRIBUTION A: Approved for public release; distribution is unlimited
Research Objective and Challenges
To exploit the uniqueness of organic/polymeric materials technologies
for enabling future capabilities currently unavailable by discovering
and improving their unique properties and processing characteristics
Challenges:
- Discover New Properties
- Control Properties
- Balance Secondary Properties
Approach:
–Molecular Engineering
–Processing Control
–Structure Property Relationship
• Program Focused on developing New and Controlled Properties
• Not applications specific, but often use applications to guide the
properties focuses
4 DISTRIBUTION A: Approved for public release; distribution is unlimited
Other Organizations That Fund Related Work
• Other Basic Research Organization in this area:
– ONR, ARO, NSF, NIH, DOE
• Other Non-Basic Research Organizations:
– AFRL/TDs, ARL, NRL, DARPA, NRO, DTRA
– DOE, JEIDDO, NIST
• Interactions with Other Agencies
– Federal Interagency Chemistry Representatives Meeting
– Tri-Service Laser Protection Information Exchange Meeting
– Joint AFOSR-ONR Organic Photovoltaic Program Review
– Tri-Service 6.1 MetaMaterials Review
5 DISTRIBUTION A: Approved for public release; distribution is unlimited
Organic Lasers Achieve CW Lasing Stephen Forrest, U of Michigan
Intensity
Time
Step Optical
Pump
Lasing
Turn-off
Why does Organic Semiconductor Laser lasing only last <100ns?
Initial conditions after pulse (<10ns)
Negligible Triplet density
Gain=Loss
Lasing begins
Later (>100ns)
Triplets build up, along with triplet losses
Gain ↓ due to S-T quenching
Loss ↑ due to T absorption
Giebink, N. C.; Forrest, S. R. Phys. Rev. B 2009, 79, 073302
Lehnhardt, M.; Riedl, T.; Weimann, T.; Kowalsky, W. Phys. Rev. B 2010, 81, 165206
Conclusion:
To reach CW lasing threshold, the triplet state density must reach a steady
state.
6 DISTRIBUTION A: Approved for public release; distribution is unlimited
Triplet Management Decreases Saturation Density
Host:
Alq3
Emitter:
DCM2
Host
Alq3
Guest
DCM2
S
T=1.8eV
T
manager
ADN
T=1.7eV
S
T=2.0eV
S
Manager
: ADN
Emission
400 500 600 7000.0
0.2
0.4
0.6
0.8
1.0
DCM2Alq3
PL (
norm
aliz
ed)
Wavelength (nm)
ADN
1.5 1.8 2.1 2.4
ADN
Alq3
Inte
nsity (
arb
. u
nit)
Energy (eV)
DCM2
Triplet State
measurement
7 DISTRIBUTION A: Approved for public release; distribution is unlimited
Exceeding the CW threshold
Conditions 2.4kW/cm2, 10Hz/18μs
Consistent with theory
Single pulse 100 μs lasing
time Degradation limited
Implications: Higher intensity and higher
efficiency OLEDs
Significant step toward
electrically pumped lasing
“Continuous-wave threshold exists for organic semiconductor lasers”, Y. Zhang and S. R. Forrest, Phys.
Rev. B, 84, 241301 (2011).
“Enhanced efficiency in high-brightness fluorescent organic light emitting diodes through triplet
management”, Y. Zhang, et al., Appl. Phys. Lett., 99, 223303 (2011).
8 DISTRIBUTION A: Approved for public release; distribution is unlimited
A Bottom-up Pathway to Chiral Metamaterials
Paras Prasad, U of Buffalo
effn Pushing toward values ≥1 will enable chiral
optical metamaterials
Synthesize new chiral conjugated polymers with high intrinsic
optical activity at visible wavelengths (molecular-scale chirality)
Control the supramolecular organization of these chiral polymers
to maximize chirality in thin film nanocomposites (supramolecular
chirality)
Create nanocomposites with inorganic components that enhance
chirality
Metallic nanocrystals (gold, silver) for plasmonic enhancement
Semiconductor nanocrystals (quantum dots) for excitonic
enhancement
Pattern nanocomposites to create chiral nanostructures (meso-
scale chirality)
9 DISTRIBUTION A: Approved for public release; distribution is unlimited
First demonstration of plasmonic enhancement of chirality
in a polymeric thin film doped with gold NPs.
B BO
O O
O
NS
N
Br Br
NS
N
n
Polymerization
Poly(fluorene-alt-benzothiadiazole) (PFBT) film with dispersed Au NPs
300 400 500 600 700 800-2000
-1500
-1000
-500
0
500
1000
CD
(md
eg)
Wavelength(nm)
PFBT
PFBT- AuNPs(8nm), 1/1
effn
0.02
“Chiral Poly(fluorene-alt-benzothiadiazole) (PFBT) and Nanocomposites with Gold Nanoparticles: Plasmonically and Structurally Enhanced Chirality,” Heong Sub Oh, Sha Liu, HongSub Jee, Alexander Baev, Mark T. Swihart, and Paras N. Prasad, Journal of the American Chemical Society, 2010, 132, 17346–17348. (cited 13 times within 1 year of online publication)
First demonstration of plasmonic enhancement of chirality in
a polymeric thin film doped with gold NPs
10 DISTRIBUTION A: Approved for public release; distribution is unlimited
B BO
O O
O
NS
N
Br Br
NS
N
n
Polymerization
First demonstration of excitonic enhancement of chirality
First demonstration of excitonic enhancement of chirality
in a polymeric thin film doped with quantum dots.
Polyfluorene film (PFBT) with dispersed CdTe/ZnS quantum dots
A: Pure PFBT B: PFBT with CdTe/ZnS
effn ~ 0.03
Manuscript in preparation
11 DISTRIBUTION A: Approved for public release; distribution is unlimited
Glass Substrate
Cross-linked
Exposed Region
Post-bake, 95 °C
Glass Substrate
Develop in PGMEA
Glass Substrate
Rinse with propanol
and dry with nitrogen
Glass Substrate
Cross-linked PFBT/SU8
nanocomposite
PFBT aggregates left behind
Process flow for PFBT/SU8
Photopatterning
Glass Substrate Glass Substrate
PFBT/SU8 film Spin-coat
PFBT/SU8
solution Pre-bake, 95 °C
Glass Substrate
PFBT/SU8 film
Shadow mask
UV light
12 DISTRIBUTION A: Approved for public release; distribution is unlimited
First demonstration of chirality enhancement by doping a chiral polymer in an
achiral photoresist matrix with subsequent photopatterning.
Photopatterning of Chiral Polymers
Polyfluorene PFBT co-dissolved with SU-8, cast into a film and photopatterned with UV light
“Dramatic Structural Enhancement of Chirality in Photopatternable Nanocomposites of Chiral Poly(fluorene-alt-benzothiadiazole) (PFBT) in Achiral SU-8 Photoresist,” Heong Sub Oh, Hongsub Jee, Alexander Baev, Mark T. Swihart and Paras N. Prasad, submitted to ACS Nano.
0.017
13 DISTRIBUTION A: Approved for public release; distribution is unlimited
Exquisite Control of Molecules to Direct Chemical Reactions
Alex Jen, U of Washington
Self-assembly of Inert Molecules to Confine
Environment
Self-assembly of Photoactive Molecules to
Control Orientation
Photon-
STM
Stochastic switching
Increased conductance of excited state
Decreased conductance of photoproduct
Kim, Houk, Ma, Jen, Weiss, Science 2011, 331, 1312. Highlighted by Chem. & Eng. News March 14, 2011.
14 DISTRIBUTION A: Approved for public release; distribution is unlimited
Molecular Design for Regio-selective Reaction on Surface
In solution: a) Diels-Alder reaction [4+2] b) Photocycloaddition [4+4]
rarely happens because of geometric constraints
+
+
PEA Photoreaction
(9-phenylethynylanthracene)
On surface: a) Creating defect sites of a
alkanethiolate SAM b) Tethering two MPEA molecules next
to each other on Au surface c) Poising in the correct orientation to
force photocycloaddition
9-(4-mercaptophenylethynyl)
anthracene (MPEA)
S H S S
9-phenylethynylanthracene
disulfide
S H
Kim, Houk, Ma, Jen, Weiss, Science 2011, 331, 1312. Highlighted by Chem. & Eng. News March 14, 2011.
15 DISTRIBUTION A: Approved for public release; distribution is unlimited
Self Assembly Monolayer with Confined MPEA
• Tunable number and size of defect
sites dependent on concentration of
n-dodecanethiol in ethanol and time
of vapor annealing
• Disulfide molecules assured adjacent
placement of molecules
16 DISTRIBUTION A: Approved for public release; distribution is unlimited
Study of Single Molecule Switching Dynamics in Confined Environment
Arrow sites: increased conductance
of molecular excited state
Box sites: Decreased conductance of
molecular photoproduct
a)
b)
17 DISTRIBUTION A: Approved for public release; distribution is unlimited
Electricity Generation with Body heat Choongho Yu, TA&M
First demonstration of electricity generation from polymeric materials
Flexible TE polymers
Connected to
a multimeter
Cut by
scissors
Voltage –Time response
Voltage
Time
18 DISTRIBUTION A: Approved for public release; distribution is unlimited
Fabrication of polymer Nanocomposites
Pour the mixture
into a plastic container
and dry at room temp.
Dry further in an oven or
dessicator to remove
micro voids and moisture
Mix CNTs and aqueous
stabilizer solution (e.g.,
PEDOT:PSS)
Disperse CNTs by
sonication and then (if
necessary) add polymer
emulsions (e.g., PVAc)
with sonication
19 DISTRIBUTION A: Approved for public release; distribution is unlimited
Controlling Junctions & Surfaces and Material Morphology
Modifying junctions and surfaces
Heat
transport
Electron transport (by hopping)
Scattering
Nanotube
Junction
Nanoparticle
Vibrational
Spectra
mismatch
Frequency
Material B Material A
Ph
on
on
de
nsit
y o
f s
tate
s
Phonon
transport
across junction
can be
suppressed.
It is feasible to dramatically
change:
- Electrical conductivity
- Thermopower
- Thermal conductivity
for desired objectives.
20 DISTRIBUTION A: Approved for public release; distribution is unlimited
Electrical Transport Increase without Changing Thermal Power
Yu et al. ACS Nano, 5, 7885 (2011). Used p-HipCo SWCNTs
(high CNT concentrations)
Power
Factor
21 DISTRIBUTION A: Approved for public release; distribution is unlimited
Double-Wall Nanotubes
Carbon nanotube wt%
0 20 40 60 80 100
Ele
ctr
ical conductivity, (
S/m
)
0
5.0x104
105
1.5x105
2.0x105
2.5x105
Therm
opow
er,
S (
V/K
)
0
10
20
30
40
50
60
70
S
CNT wt%
0 20 40 60 80 100S
2
W/m
-K2
)0
200
400
600
800
800 %
improvement in
Power Factor
over SWNT
Double-wall carbon nanotube wt%
DWNT + PEDOT:PSS only composites
22 DISTRIBUTION A: Approved for public release; distribution is unlimited
Layer by Layer Removal of Graphene: single-atomic-layer-resolution lithography
Dimiev, A.; Kosynkin, D. V.; Sinitskii, A.; Slesarev, A.; Sun,
Z.; Tour, J. M. “Layer-by-Layer Removal of Graphene for
Device Patterning,” Science 2011, 331, 1168-1172.
23 DISTRIBUTION A: Approved for public release; distribution is unlimited
Layer-by-layer removal and patterning of GO
The method works with the four different types of graphene and graphene-
like materials: -graphene oxide,
-chemically converted graphene,
-chemical vapor–deposited graphene (CVDG),
-and micromechanically cleaved (“clear-tape”) graphene
24 DISTRIBUTION A: Approved for public release; distribution is unlimited
Graphene nanoribbons heat circuit as de-icing coating for phased array antennas and radomes
Yu Zhu; Wei Lu and James M. Tour*
Department of Chemistry and Smalley Institute, Rice University, Houston, TX 77005
The MWCNTs are split by the potassium metal vapor
treatment and retain the resiliently rigid mechanical
properties of the parent nanotubes. The produced
graphene nanoribbons are highly conductive (800
S/cm) and dispersible in solvents such as
chlorosulfonic acid and othordichlorobenzene. ACS
Nano 2011, ASAP.
A thin graphene nanoribbon film is practically transparent for RF
electromagnetic waves.
With the layer thicknesses around 100 nm ,the film is suitable for a de-icing
cover to replace conventional heat circuits for phased array antennas and
radomes.
Quenched with styrene
2 um
Quenched with isoprene
4 um
25 DISTRIBUTION A: Approved for public release; distribution is unlimited
Large Area De-icing coating for Antenna and Radome
De-icing test under -20°C conditions
Collaboration with Lockheed Martin
•Thickness of heating layer is not more than 100 nm
•Transparency for RF radar signals of any polarization
•10 grams of graphene nanoribbons per 10 m x 10 m antenna
aperture/face. Cost is $10 in nanoribbon starting material
Spray coated GRN film on flexible
polymer substrate
26 DISTRIBUTION A: Approved for public release; distribution is unlimited
Growth of Graphene from any Carbon Source
J. Tour, Rice University Impurities remain on top of foil
1000°C
Ruan, G.; Sun, Z.; Peng, Z.; Tour, J. M. “Growth of Graphene from Food, Insects,
and Waste,” ACS Nano 2011, 5, 7601–7607.
27 DISTRIBUTION A: Approved for public release; distribution is unlimited
Graphene from Girl Scout Cookies
Google “graphene girl scout cookie”= 51,000 hits.
The YouTube video has 40,000 hits too.
Converted to a single sheet of graphene, one box of Girl Scout Cookies can be
worth $15 billion, and would cover nearly 30 football fields
28 DISTRIBUTION A: Approved for public release; distribution is unlimited
Upconversion with Terrestrial Solar Photons
29 DISTRIBUTION A: Approved for public release; distribution is unlimited
Upconversion-Powered Water Splitting Photoelectrochemistry
F. Castellano, Bowling Green U
Chem. Commun. 2012, 48, 209-211.
The first example of water-splitting photoelectrochemistry being
operated solely under the influence of upconverted photons.
30 DISTRIBUTION A: Approved for public release; distribution is unlimited
Upconversion Visualized in a PEC Cell
Photograph of the cell in action, pumped
by long-pass filtered lamp light delivered
via fiber optics to the outside of the
PhotoElectroChemical (PEC) cell
Shuttered current/time response of a
WO3 photoanode biased to +0.9 V vs
Ag/AgCl in 1.0 M H2SO4
31 DISTRIBUTION A: Approved for public release; distribution is unlimited
Recognitions
Metamaterials and plasmonics for rf photonics
Rf Antenna
Rf waveguide
EO modulator
Optical Fiber Optical Fiber
Signal out Signal out
New Hybrid Antenna
Rf Input
On Going Transition:
EO Polymer is one of the key technologies for its development in AFRL
32 DISTRIBUTION A: Approved for public release; distribution is unlimited
Flexible Photodetector
Summary
• Program Focused on developing New and Controlled
Properties
• Not applications specific, but often use applications to guide
the properties focuses
• Scientific Challenges
- Discover New Properties
- Control Properties
- Balance Secondary Properties
• General Approaches
- Molecular Design
- Processing Control
- Establish Structure Properties Relationship
top related