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Organic Materials Chemistry18 March 2011
Charles YC LeeProgram ManagerAFOSR/RSA
Air Force Office of Scientific Research
AFOSR
Distribution A: Approved for public release; distribution is unlimited. 88ABW-2011-0803
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2011 AFOSR SPRING REVIEW230CX PORTFOLIO OVERVIEW
NAME: Charles YC Lee
BRIEF DESCRIPTION OF PORTFOLIO:To exploit the uniqueness of organic/polymeric materialstechnologies for enabling future capabilities currently unavailable bydiscovering and improving their unique properties and processingcharacteristics
LIST SUB-AREAS IN PORTFOLIO:Photonic Polymers/Organics
Electronic Polymers/OrganicsPermittivity and Permeability ControlNanoTechnologyOthers
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Reconfigurable Functionalities
Conformal Functionalities
Currently Unavailable Capabilities
Transformational Opportunities
Plastic SensorCarpet for Space
SurveillanceHigh Fidelity UAVControl Module
Conformal Smart
Skin for Sensorsand IRCM
Conformal FocalPlane Arrays
Reflective/Absorptive Surfaces
Enable Innovative Applications Limitedby imagination
More appropriate for Opportunity Driven,Not strong in Requirement Pull
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Other Organizations That FundRelated 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
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Program Trends
New Interests:Switchable Properties
Decoupling Coupled PropertiesStrain effects on Polymer PropertiesPT Materials (Parity-Time reversal Materials)
Continued to focus on achieving new functionalProperties
PhotonicElectronic
Magnetic (Spin, Chirality)
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Recent Transitions
Rewritable 3D Hologram to DARPAand IARPA
TPA 6.1 Results led to AFRL/RX 6.2
and 6.3 Developments
Compact Non-Mechanical BeamSteerer to RW and RY
Bistable Organic Devices Licensed toAustralian startup Sillana for R-RAMDevelopment
Substrate
Organic layer
Middle Metallayer
Electrode
ON state
OFF state
10-7
10-6
10-5
10-4
10-3
10-2
10-1
0 0.5 1 1.5 2 2.5 3
CurrentDensity(A/cm
2)
Voltage (V)
1st bias
2nd bias
400 450 500 550 600 650 700 750
Intensity(A.U.)
(nm)
EX: 400 nmEX: 400 nmEX: 400 nmEX: 375 nm
100% AF240 THF (EX: 375 nm)
Solution
Thin filmat various locations
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Polymer composites with largepermanent conductivity changes
Yi Liao, U of Central Florida
Photochemically or thermally controlling the conjugation anddopant to control the electronic properties of organic materials.
Nonconjugated PolymerActive or Inactive Dopant
INSULATOR
Conjugated PolymerInactive Dopant
SEMICONDUCTOR
Conjugated PolymerActive dopantCONDUCTOR
Turn on conjugation
Break conjugation
Breakconjugation
Turn onconjugation in
the presence ofan active dopant
Deactivatedopant
Activate dopant
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Photo-acid generation to convertnon-conducting PA to Conducting PA
HN
HN N N
n m
Emeraldine base form of polyaniline
INSULATING, conuctivity < 10-8 S/cm
HN
HN N N
n mH H
H+
HN
HN N
HN
n mH
Emeraldine salt form of polyanilineCONDUCTING.
Best value in literature shows only 1-2 orders of magnitude improvement
in conductivity even with equal weight of PhotoAcid Generator (PAG) Postulate that lack of proton mobility in solid state causes protonation atthe undesirable diphenyl amine location, resulting in break-up ofconjugation.
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PAGOptimization PVAOptimization
OHn
PVA
OH OH OH O+ OH OH
H+
HH O O+ OHHH H
A simple illustration of how PVA may increase proton mobility
New Composite to EnhanceConductivity Changes
triphenylsulfonium triflate, 254 nmS+
-O S
O
O
CF3
Photo Acid Generator
Proton Mobility Enhancer (Polyvinyl alcohol (PVA))
The left figure shows that
there is an optimized PAG
level. The right figure shows
that too much PVA lowers theconductivity.
This system was optimized and a 7 order of magnitude conductivity change to 10-2
S/cm can be reproducibly achieved with a optimized PANI-EB/PVA/PAG ratio of
1:1:0.6. (5 orders of magnitude improvement over best values reported in theliterature)
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H-Bonding Photo-Acid Generator(PAG)
H-bonding PAGS+
HO OH
S
O
-O CF3
O
S+
O
OH
NN
H
N
H
n
N
N
HN
n
The PAG can from H-bonding with PANI.
Preferred ReactiveSite
Mixing the H-bonding PAG with PANiwithout PVA or with ~1% PVA canachieve a conductivity of ~10-1 S/cmafter photoirradiation, which is oneorder of magnitude higher than theprevious composite.
Effects of Addition of H-bonding PAG Prevent aggregation of PAG PAG bonded to site for favorablereaction with PANi
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Effect of molecular constraints onoptoelectronic behavior of conjugated polymers
Arnold Yang, National Tsing Hua University, Taiwan
The shear flow induced by thin film dewetting instability
was found to induce large PLQE enhancements
ThermalDewetting
SolventDewetting
400 450 500 550 600 650 700
0
50
100
150
200
250
300
350
NormalizedPLintensity(a.u./nm)
Wavelength (nm)
As-deposited film
undewetted film
Residual films
400 450 500 550 600 650 7000
5000
10000
15000
20000
25000
30000
PLintesnity(a.u.)
Wavelength (nm)
Droplet on wafer
Droplet on glass
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Photoluminescence Enhancementunder stress
*
*
OMe
O
Bu
Et
n
HC
H2C **
nMEH-PPV (Poly[2-methoxy-
5-((2'-ethylhexyl)oxy)-1,4-phenylenevinylene])
PS: MW = 2M g/mol. (disp.~1.06) MEH-PPV: MW = 150~250kg/mol (disp. ~5) film thickness: 0.5mm
Polystyrene
H-v H-h V-h V-v
0
2
4
6
8
10
12
14
Enhancementfactor(Peakarea)
Polarization of laser + Direction of sample
405 nm
488 nm
532 nm
H-v H-h V-h V-v0
2
4
6
8
10
12
14
Enhancementfactor(Peakarea)
Polarization of laser + Direction of sample
405 nm
488 nm
532 nm
Intra-molecular emission Inter-molecular emission
Emission: 550 to 575 nm Emission: 580 to 610 nm
Excitation Excitation
C
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Chemomechanics: reaction dynamicsunder mechanical loadsRoman Boulatov, University of Illinois
Chemomechanical rate law is valid for reactants of any sizeFragmentation of strain-free polymer, ko
Fragmentation of stretched polymer, k(Ft)
ko
FtFt
k(Ft)
weak link
n
m
Mechanosen
sitive
monomer
n
m
Macrocycle of Zstiff stilbene: reactivemonomer is strain-free
Macrocycle of Estiff stilbene: reactivemonomer is strained Force controlled by linkers up to 700 pN in
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Good Agreement between Experimentsand Theoretical Prediction
Measurements validate the chemomechanical predictions
for bimolecular reactions
-6
-4
-2
0
2
4
6
0 200 400 600
Ft, pN (calculated)
ln(k(Ft)/ko)
Direction of tensile force
acceler
ation
inhibition
Points: experiment; lines: theoryReactions:
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Upconversion with incoherent lightBimolecular approach allow flexibility in design ofsystems and performance parameters
Photoluminescence and Photochemical Upconversion
Prof. Felix N. Castellano, Department of Chemistry & Center for Photochemical Sciences, BGSU
Incoherent Light UpconversionFil Castellano, Bowling Green State U
31
S0
1MLCT
3MLCT
E3An*
1An*
3An* +
3An* (TT Annihilation)
Triplet EnergyTransfer
N
N
N
N
N
N
N
N
N
N
N
N
Ru
2+
[Ru(dmb)3]2+
Anthracene
+
[Ru(dmb)3]2+* + An [Ru(dmb)3]
2+ + 3An*
3
An* +3
An*1
An* + An
OriginalBimolecularPrototype:
x 2
Sandwiched state model originated in 1962: Parker and Hatchard Proc. Chem. Soc. 1962, 386-387.
Energy Requirements for Sensitized AS Fluorescence
Based on Sequential Linear Absorption and TT Annihilation
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Improved BODIY Dyes forIncoherent Upconversion
BD-1 BD-2
N
N N
N
PtN NB
F F
N NB
F F
Pt-porphyrin
triplet sensitizer
Advantages over Aromatic HydrocarbonsHigh singlet fluorescence quantum yields (Primary)Resistance to photobleaching, photooxidation
Photon Upconversion of BD-1 and BD-2 in Benzene, exc = 635 nmupconversion quantum efficiencies up to 8%
BODIPY - boron-dipyrromethene
Ref: Singh-Rachford, Haefele, Ziessel, and Castellano,J. AM. CHEM. SOC. 2008, 130, 1616416165
U i ith T t i l S l
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Upconversion with Terrestrial SolarPhotons
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Green to Blue Absorber andEmitter Combination
NN
N N
Pd
Pd(II)octaethylporphyrin (PdOEP)9, 10-diphenylanthracene (DPA)
532 nm Laser Pointer
Polyurethane Bar
Upconverting Polyurethane Bar Containing PdOEP/DPA
Polyurethane Bar Containing PdOEP
U i i
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Upconversion inGlassy Matrix
Samples contain ~25% w/w DPA and ~0.25% w/w PdOEP
1.4 x 1.4 cm, 200 mm thick transparent film
Chromophores and PMMA were co-extruded from a twin screw
extruder then hot-pressed and quenched into a thin film.
400 425 450 475 500
0
50000
100000
150000
200000
250000
PLIntensity(counts)
Wavelength (nm)
0.4330.3560.2480.2000.1200.0800.0650.0380.035
PMMA Sample
Spot #1Power Density
(W/cm2)
0.00 0.25 0.50 0.75 1.00
0.00
0.25
0.50
0.75
1.00
UpconvertedEmissionIntensity
Excitation Intensity
Spot #1
PL is linear power dependence at RT
Mechanism of Annihilation is yet unknown
T d IR
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Towards near IR toVisible Up Conversion
N
NN
N
Zn
N
NN
N
Zn
N
N
NN
N
N
Ru N
R
R
R
R
R= 2,6-bis(3,3-dimethyl-1-butyloxy)phenyl
Pyr1RuPZn2 - Sensitizer
Tetracene - Acceptor
MLCT*
GS
3MLCT*
3Tetracene*
TTA
3Tetracene*
3Tetracene*
1Tetracene*
ISC
TTET
fl = 0.17
T = 0.62
tT = 400 ms
exc = 780 nm
ex = 780 nm
em = 505 nm
Anti-Stokes shifted by 0.86 eV
New record anti-Stokes shift for sensitized TTA
lex = 780 nm, Deaerated MTHF
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First Rewritable 3D Hologram
Nasser PeyghambarianU of Arizona
Image recorded usingpolarization multiplexing
technique and reconstructedwith white point source.
Image reconstructed with dualpoint source from
hologram with one reference.
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6 Sample and Images
O f T T B kth h f
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One of Top Ten Breakthroughs of2010 in physicsworld.com
Physics Worldreveals its top 10 breakthroughs for 2010 Dec 20, 2010
Anyone who uses physics to realize a scene fromStar Warsdeserves a place in our top 10, which iswhy Nasser Peyghambarian and colleagues at the
University of Arizona and Nitto Denko TechnicalCorporation come in at number eight. In 1977audiences were wowed by the special effects in thatcinematic classic, which included a hologram ofPrincess Leia making a distress call to Obi-WanKenobi. Now, Peyghambarian and team have taken a
big step towards making such real-time, dynamicholograms a reality by inventing a photorefractivepolymer screen that reacts very quickly to laserlight.
F-4
Phantomholograph
8th place: Towards a Star Warstelepresence
-----and Material Chemistry makes it possible-----
Switchable Surface Properties by
http://images.iop.org/objects/phw/news/14/12/18/holo1.jpghttp://images.iop.org/objects/phw/news/14/12/18/holo1.jpghttp://images.iop.org/objects/phw/news/14/12/18/holo1.jpghttp://physicsworld.com/cws/article/news/44240http://physicsworld.com/cws/article/news/44240http://physicsworld.com/cws/article/news/44240http://physicsworld.com/cws/article/news/44240http://physicsworld.com/cws/article/news/44240http://physicsworld.com/cws/article/news/44240http://physicsworld.com/cws/article/news/44240http://images.iop.org/objects/phw/news/14/12/18/holo1.jpghttp://images.iop.org/objects/phw/news/14/12/18/holo1.jpghttp://images.iop.org/objects/phw/news/14/12/18/holo1.jpghttp://images.iop.org/objects/phw/news/14/12/18/holo1.jpghttp://images.iop.org/objects/phw/news/14/12/18/holo1.jpghttp://images.iop.org/objects/phw/news/14/12/18/holo1.jpg -
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Switchable Surface Properties byAnnealing
Anish Tuteja, U of Michigan
Anneal
in water
Anneal
in air
2 mm
2
mm
A
W
Hexadecane WaterA* 1.4 A* 3.9
A* 0.9 A* 3.1
Chhatre et al. Langmuir(2009) 25 (23), 13625-13632.
Variation in apparent contact angles (*) due tosequence of annealing treatments in water and dry air
PEMA- poly-ethyl-methacrylate
POSS- fluorinated Polyhedral oligomeric silsesquioxane
Filled symbols advancing contact angles
Half-filled symbols receding contact angles
PEMA Tg 65oC
Annealing Temp 90oC
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Oil-Water Emulsion Separation
250
200
150
100
50
0
Flux(L/m
2
hr)
1801501209060300Time (min)
Permeate through HL/OPPermeate through HP/OL
Very high (> 99%) emulsionseparation efficiency
Heat in TGA to 105
Cand hold for 70 minutes
No decrease in flux due tofouling by oil
FMPS method for computational
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Gimbutas, Greengard30
FMPS method for computationalelectromagneticsLeslie Greengard, NYU
Meta-material design will require rapid forward modeling
of Maxwells equations in complex aperiodic micro-structured materials
FMPS (Fast Multi-Particle Scattering) provides new multiple scattering formalism
allows for complex particle shapes
uses rigorous reduced order model for particles
Far field for each structure expressed in terms of vector sphericalharmonics (Debye potentials/Mie theory)
Near field computed from solution to Muellers integral equation
Has been coupled with fast multipole (FMM) acceleration
Will allow for anisotropic inclusions in isotropic background material
Fully resolved solution, straightforward convergence testing
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Assemblies of paired NRs
EHk
559nm
25x25x75nmsep.: 40nm
31
882 pairs
phase:
standard discretization would involve >1M
degrees of freedom
No Difference between Responses
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No Difference between Responsesof Periodic & Random structure
E-field below paired NR layers25x25x75nmsep.: 40nm
21 x 21 x 2 z
magnitude
magnitude
phase
phase
negative phase-. . 10%vol fr
12
nd
attenuation-
E
Hk
Periodic lattice
Random position
No Difference between Responses
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No Difference between Responsesof Periodic & Random structure
-response of periodic & random structure is essentially same!
3z
magnitude
magnitude
phase
phase
periodiclattice
randomposition
-negative phase
12
nd
attenuation-
At
Response of Single NRs and Pairs
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Response of Single NRs and Pairsis Similar
E-field below paired & uniform NR layers
z
magnitude
magnitude
phase
phase
randomposition
random
position
NR pairs
uniformdist. of
single NRs
Hi h d it bl f NR i
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magnitude
magnitude
phase
phase
High density assembly of NR pairs
. . 10%
156
42o
vol fr
d nm
. . 34%
105
70o
vol fr
d nm
12
nd
559nm
0.58n
0.04n
-need vol.fr. ~18% for n=0, vol.fr.>33% for n=-1.
First Reported Organic Polariton
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First Reported Organic PolaritonLasersS. Forrest, U Michigan
Goal: To observe electrically excited lasing in organic semiconductors
Problem: Excited state (exciton) annihilation prevents electrical pumping of semiconductor lasing Approach: Employ exciton-photon coupling in high Q microcavities to create a Bose-Einstein polariton
condensate to lase at extremely low threshold.
Achievement: First demonstration of polariton lasing in an organic material
What is a polariton? Polariton dispersion
Energy
-E
In-planewavevector - k
uncoupledcavity dispersion
uncoupledexciton dispersion
strongly coupled state,microcavity polaritons
Publication: Room-temperature Polariton Lasing in an Organic Single Crystal Microcavity. S. Kena-Cohenand S. R. Forrest, MRS Fall Meeting, invited, Paper O13.4, Boston (Dec. 2, 2009).
M h d d R l
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Methods and Results
Below threshold(P=880 pJ)
Above threshold(P=389 nJ)
200 mm 200 mm
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1 10 100
1E11
1E12
1E13
1E14
P
olaritonDensity(c
m-3)
Temperature (K)
Polariton
LED
PolaritonLaser
zoneBrillouin
RkTkEkEcritical beN /2
/)0()( 1
1
The critical density at 300K for condensation is ~2x1013/cm3
Threshold is1000X lower than normally pumped lasing
Thermodynamic Limit
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Summary
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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