8. erstfeld - afosr taiwan nanoscience
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AFOSR TAIWAN
NANOSCIENCE PROGRAM(AND AOARD CHEMISTRY)
16 March 2011
Dr. Thomas E. ErstfeldProgram Coordinator
AFOSR/RSZ
Air Force Office of Scientific Research
AFOSR
Distribution A: Approved for public release; distribution is unlimited. 88ABW-2011-0760
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A Salute to Our Host!
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2011 AFOSR SPRING REVIEWTAIWAN NANOSCIENCE OVERVIEW
NAME: Tom Erstfeld
BRIEF DESCRIPTION OF PORTFOLIO:
Taiwan Nanoscience Program, Chemistry, Materials and Processing,Technology for the Warfighter
LIST SUB-AREAS IN PORTFOLIO:
NANOSCIENCE Electronics, Electro-optics, Physics, Chemistryand Materials Science, Mesoscale Mechanics
CHEMISTRY All Areas
PARTICULATE MECHANICS Program with RW
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Scientific Challenges
Precise control of materials and their processing at theatomic/molecular scale will impact everyday life
Advanced sensing
Faster, more efficient computing
Quantum mechanical effects The list is endless!
People are rapidly advancing the state of the art, but
What is the underlying physics?
What knowledge is required to achieve tunablity ofnanomaterials?
How does one transition from the nanoscale to themacroscale? What challenges exist in the mesoscale?
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Transformational Opportunities
Nanotechnology is progressing rapidly, and no oneknows where it will lead, but its effects will beworldwide and will be revolutionary
A few good guesses
Nanoelectronic materials
Components for nano-electromechanical systems
Realization of quantum computing
Small, ultrasensitive sensors
Nanobiology and nano-based medicine
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Other Organizations That FundRelated Work
What organization isnt funding nanotechnologyresearch? The list is shorter!
U.S. National Nanotechnology Initiative spent $1.8B in 2010
Global public investment estimate of $8.4B in 2008, with a
further $8.6B in corporate funding
Whats unique about this program
Influence: Air Force has gained access to some of Taiwansbest researchers, and relationships have begun and have
grown; we help guide research directions Leverage: the Taiwan Program began in 2003, AOARD has
influenced and harvested the investment of $40M-worth ofTaiwans $900M program
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Program Trends
Program is making changes in its priorities: Stops Starts
Gallium nitride technology Graphene technology
Medical-related applications Nanofluidics
The biggest change is in programmatics:
In FY 2011 integrated proposals from Taiwan and the U.S.will be required
Taiwans NSC will fund the Taiwan-based partner
AFRL will fund the U.S.-based partner
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Representative Projects
Tin-Based IV-IV Heterostructures
Polymer Bulk-Heterojunction Solar Cells
Chemical Reactivity of Complex Systems
Bio-Inspired Assembly of Artificial PhotosyntheticAntenna Complexes
Aromatic and Antiaromatic Porphyrinoids
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Scientific objective
Determine how to integrate photonic or optical devices with Si
Scientific/technological approach
Use molecular beam epitaxy (MBE) to create GeSn/Geheterostructures to allow integration of direct bandgap devicesinto Si platforms
Breakthrough opportunity
Use of various alloy compositions of GeSn allows the bandgapof the materials to be engineered to make devices requiring
tunability or multijunction capabilities
Partners:
Coordinating with Gernot Pomrenke, RSE
Collaborating with Richard Soref, RYHGreg Sun, University of Massachusetts Boston
Tin-Based IV-IV HeterostructuresHenry Cheng, National Taiwan University
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Momentum (k)
L G
-Sn 0%
-Sn 5%
-Sn ?%
Direct!!!
TEM image of GeSn film Micrograph at interface:
misfit dislocations
Sn-based IV-IV compounds for direct bandgap
0 2 4 6 8 10 12 140
5
10
15
20
25
30
Sncomposition(%)
Position (#)
STEM image of GeSn film
EDS measurement of GeSnfilm showing Sn nearly
uniformly distributed
0.5 0.6 0.7 0.8 0.9-0.2
0.0
0.2
0.4
0.6
0.8
1.0
absorptionedge indirect band
Bulk Ge bandgap
(room temperature)
trans
Energy (eV)
Bulk Ge
GeSn (2%)
absorption edge of direct band of GeSn
Absorption spectra of GeSn showingindirect and direct optical transitions
Tin-Based IV-IV Heterostructures
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Tin-Based IV-IV Heterostructures
Theoretical modeling on the energy band of Sn-based disorder effect
on the band gap of GeSn alloys
Experimental reports indicate
direct gap appears at x > 0.112and 0.1 > x > 0.06
First-principle calculations usingsupercell
Sn is placed as denoted by 1-8in above figure
Direct gap is observed at1, 2, 4, 5, 6, 7, and 8 sites
Formation energy depends
on the number of Sn-Snbonds
Results reveal that growingconditions and posttreatment of GeSnsamples should
significantly affect the gapproperties of GeSn alloys
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Scientific objective
Determine optimum fabrication techniques for high-performancesolar cells
Scientific/technological approach
Use novel interfacial modification in the polymer/electrodejunction to markedly enhance power conversion efficiency
Breakthrough opportunity
Improve cell performance through the better collecting efficiencyof the electrodes for the photo-excited charge carriers
Partners:
Co-funding provided by Charles Lee, RSA
Collaborating with Bin Hu, University of Tennessee
Polymer Bulk-Heterojunction Solar CellsTzung-Fang Guo, National Cheng Kung University (Taiwan)
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First BHJ Polymer-Based ODEP Devices
rr-P3HT
PCBM
Optically-induced dielectrophoretic (ODEP) devices
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Photo Responses of R-G-B Light from Projectors
Green illumination has the largerDEP force due to better overlap withthe absorption of P3HT
High extinguishing coefficientfor P3HT: 9.6 x 105cm-1 at530 nm for-* transition)
Low lateral diffusion for theprecisely and effectively opticalmanipulation: low excitondiffusion length (~10 nm)
Variable optical responses:selections of differentconjugated polymers as theactive layer.
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Manipulation of Particles by Different Color Rings
Appl. Phys. Lett. 96, 113302 (2010)
A non-contact approach to exclude or collect the polymer particles by shrinkingone of the two light rings with different colors and diameters
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Chemical Reactivity of Complex SystemsKopin Liu, Academia Sinica (Taiwan)
Scientific objective
Understand and ultimately control the reactive outcome ofcomplex systems by the vibrational excitations of a reactant
Scientific/technological approach
Use unique cross-molecular beam apparatus Breakthrough opportunity
Achieve control of chemical reactivity by steric effects
Other information:
Co-funding provided by Mike Berman, RSA
Awarded Alexander von Humboldt Research Award in 2010
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Chemical Reactivity of Complex Systems
F + HCD3
DF + CHD2(1
1)
HF + CD3x
formation
depletion
Reactions of methane with F, Cl,
and O(3
P): prototypical of H-atomabstraction, but with vastly differentenergetics and barrier properties
Exciting a stretching mode of abond should increase the likelihoodof the bond breaking
Study of the F + CHD3 reactionshows, counter-intuitively, excitingthe C-H bond impedes its breakageto form HF + CD3
The rate of the other reactionpathway leading to DF and CHD2 also slows down
This unexpected finding waspublished in Science325, 303(2009), and has since receivedwide publicity in C & E News,RSC Chemistry World, and Nature
Chemistry
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D
D
D
O
O
O
HC
D
D
D
F
F
F
HC
Exciting the C-H stretch of CHD3 reactant inducesprecisely oppositesteric-effects on chemical reactivity !
O(3P) + CHD3:focusingeffect enlarging the reactivecone of acceptance
F(2P) + CHD3: defocusing hindrance of the overall
reaction rate, particularly the HF channel
Bio Inspired Assembly of Artificial
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Bio-Inspired Assembly of ArtificialPhotosynthetic Antenna Complexes
Mamoru Nango, Nagoya Institute of Technology (Japan)
Scientific objective
Use natural photosynthetic process to produce low-cost sensorswith inherently high photon-capturing and charge-separationefficiencies
Scientific/technical approach
Control the direction and orientation of photosynthetic antennapigment complexes on electrodes
Breakthrough opportunity
Develop sensors having light-conversion efficiency intochemical energy of nearly 100%
Partners:
Co-funding provided by Hugh DeLong, RSL
Collaborating with Minoru Taya, University of Washington
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The X-ray structures and AFM image of antenna complexes from purple photosynthetic bacteria
carotenoid
LH-a
BChl a
LH-bLH2 complex from Rps. acidophila 10050
LH-a & -b /
BChl a
LH1-RC core complex from Rps. palustris
Bacteriochlorophyll a
(BChl a)
N N
N N
O
O
OO
COOCH3
Mg
3
Carotenoid
OCH3
OCH3
The antenna complexes efficiently realize various
photosynthetic functions using cofactors (BChl a
and carotenoid) assembled into the apoproteins:The energy conversion yield is ~100%
LH1-RC
LH2
R.J. Cogdell, et. al, Nature, 374, 517 (1995) R.J. Cogdell, et al., Science, 302, 1969 (2003)
~11nm~6.8nm
AFM Image
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Assembly of LH2 onto line-patterned substrate
Au on SiO2
Etching
Au: 20 nm
5 mm
Patterned substratefor organization ofLH2 and LH1-RC
700 800 900-0.10.00.10.20.30.40.50.6
0.000
0.001
0.002
Absorbance
Wavelength/nm
40 mm40 mm
SiO2Au
Fluorescence (LH2)
Epi-FLBright Field
In solution
On substrate
Absorption spectra of LH2
A clear fluorescence of LH2 with SH-tag wasobserved at the Mal sites on the substrate withlined patterning when illuminated at near IR region(right figure)
On-going:
LH1-RC with His-tag will be further assembled onthe NTA site to produce an efficient energy transferfrom LH2 to LH1-RC on the substrate fordevelopment of new type of nanosensors and
nanosemiconductors (nanobiophotonics)
Aromatic and Antiaromatic Porphyrinoids
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Aromatic and Antiaromatic PorphyrinoidsDongho Kim, Yonsei University (Korea)
Atsuhiro Osuka, Kyoto University (Japan)
Scientific objective
Systematically propose, synthesize, and characterize promisingcandidate molecules having large third-order non-linear opticalproperties
Scientific/technological approach
Atsuhiro synthesizes expanded porphyrins, while Donghoperforms a myriad of femtosecond spectroscopic analyses
Breakthrough opportunity
Improved eye-protection from lasers, advanced photocatalysts
Partners:
Co-funding provided by Charles Lee, RSA, and Tom Cooper, RXP
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Aromatic and Antiaromatic Porphyrinoids
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Hckel topology
[4n+2] : aromatic[4n] : antiaromatic
MO energy levels
Double-sided
sign inversion[4n+2] : antiaromatic[4n] : aromatic
Single-sided
Hckel Aromaticity
Mbius Aromaticity
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Antiaromatic
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Aromatic
Aromatic and Antiaromatic Porphyrinoids
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Aromatic and Antiaromatic Porphyrinoids
First time that thephysical and chemical
properties of variousexpanded porphyrinshave been closelyrelated to aromaticity
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Recent Transitions
Tin-Based IV-IV Heterostructures
Transitioned to Richard Soref, RYH
Aromatic and Antiaromatic Porphyrinoids
Supported by and transitioned to Tom Cooper, RXP
Passivation of Indium Arsenide and GalliumAntimonide High Dielectrics
Supported by and transitioned to Gail Brown, RXP
Particulate Mechanics Supported by and transitioned to Lalit Chhabildas and Bill
Cooper, RWM
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The Future
New business model for the Taiwan Nanoscience
Program in 2011
Program is based on model used for Korea NBIT Program:
Ensures partnerships
Ensures transitions
Secures Taiwanese investment
Increased emphasis on chemistry
Reaction Dynamics
Catalysis
Ionic Liquids
Biochemistry
Synthesis
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Questions?