Transcript Slides - Jung Y. Huang

Active Spectroscopy and Optical Imaging for
Functional Materials with Engineered Architectures
Jung Y. Huang and K. H. Wei
Motivation of the Research: Exploring plausible methods for
characterizing functional materials with interacting subunits
arranged in a hierarchically organized structure.
http://www.jyhuang.idv.tw/teach.php.htm
Characterize Material System via Quantum Control
 Go beyond the pump-probe spectroscopic techniques by manipulating excitation
laser pulses for controlling the quantum evolving course of molecular dynamics.
 The crucial issue of the quantum control is the inverse problem, i.e.,
how to retrieve information of the system dynamics from the known
optimal pulse ---- Active
Spectroscopy
Characterize Material System via Quantum Control
spectrometer
Input pulses
Beam splitter
Objective
lens
SLM
sample
XY scanning stage
Characterize Material System via Quantum Control
Field
Amplitude
Phase
Characterize Material System via Quantum Control
 Coherent control offers an opportunity to distinguish
the coherent process from incoherent optical processes.
Ω
↓
2πc/ω
Characterize Material System via Quantum Control
Current Achievements:
1. Ming C. Chen, Jung Y. Huang, Qiantso Yang, C. L. Pan, and Jen-Inn Chyi: “Freezing phase scheme for fast adaptive
control and its application to characterization of femtosecond coherent optical pulses reflected from semiconductor
saturable absorber mirrors” -J. Opt. Soc. Am. B 22, 1134-1142 (2005).
2. M. Z. Chen, Jung Y. Huang, and Li. J. Chen: “Coherent control multiphoton processes in semiconductor saturable
Bragg reflector with freezing phase algorithm” -Appl. Phys. B 80, 333–340 (2005)
3. Ching-Wei Chen, Jung Y. Huang and Ci-Ling Pan: “Pulse retrieval from interferometric autocorrelation measurement
by use of the population-split genetic algorithm” -Optics Express 14, No. 22 (2006), in press.
Future Development: Quantum-control technique for probing molecular
recognition mechanism of Biomolecules.
optimized
antioptimized
Important Question: What is the characteristic
frequency among these binding nano objects?
Raman Imaging with Photon Counting Lock-in Detection
 Lock-in detection functionality was developed to
detect an extremely weak optical signal for 2D
mapping electro-optic active species in a complex
optical film.
Intensity (arb. units)
Unmodulated Raman
Spectrum of SSFLC
9000
(a)
8000
7000
Lock-in Detected Raman Spectrum
360
4800
(c)
1118
270
1610
180
2400
1326
1446
1505
90
1200
0
900
0
1200
1500
1800
-1
Wavenumber (cm )
2100
1500
1800
Wavenumber (cm )
ampl.
phase
3600
1200
-1
Phase (degrees)
Amplitude(arb. units)
900
2100
Raman Imaging with Photon Counting Lock-in Detection
340
250
(b)
2400
150
1600
100
800
50
0
0
0
600
1200
1800
Frequency (Hz)
2400
3000
ampl.
phase
320
2400
300
1600
280
800
260
0
Phase (degrees)
200
Amplitude(arb. units)
ampl.
phase
(a)
Phase (degrees)
Amplitude(arb. units)
3200
3200
240
0
600
1200
1800
2400
Frequency (Hz)
3000
 The amplitude (filled circles) and the phase (open squares) of a phaseresolved Raman peak (a) at 1118 cm-1 and (b) at 1610 cm-1 as a function of
modulated frequency Ω.
 The reduction factor from the phase relaxation time to the amplitude
relaxation time reveals the disordering effect of the molecular alignment by the
high-frequency driving.
Raman Imaging with Photon Counting Lock-in Detection
• Achievement: The technique yields useful 2D phase-resolved
distribution of an electro-optic active species in a complex film
with a detection sensitive down to single molecular level.
Y. H. Wang, M. C. Chen, and Jung Y. Huang: “Raman Imaging of Surface-Stabilized Ferroelectric Liquid
Crystal Film with Photon Counting Lock-in Detection” --J. Opt. Soc. Am. B (2006), submitted.
Enhanced Electro-Optical Response from Engineered
Architectures with Self Assembling Nanotechnology
 Motivation of the Research: Exploring the plausible ways to
realize functional materials with enhanced EO responses from
interacting subunits combined in a hierarchically organized
structure.
 The enhanced EO properties can be considered to originate from a
combined effect of enhanced charge transport and enhanced light
emission.
n-Type
p-Type
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+
pn-junction
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I. Enhanced Charge Transport
System 1: Enhanced electron transport through ordered nc-CdS
constituents in the PV4P nanodomains of PS-b-P4VP copolymer
Major Achievement: The electron transport via CdSe QDs confined in
the poly(4-vinylpyridine) nanodomains at 48vol% was found to be 10
times larger than that in a random distribution.
Chung-Ping Li, Kung-Hwa Wei and Jung Y. Huang: “Enhanced Collective Electron Transport by CdSe Quantum Dots SelfAssembled in the Poly(4-vinylpyridine) Nanodomains of a Poly(styrene-b-4-vinylpyridine) Diblock Copolymer Thin Film” Angewandte Chemie International Edition 45, 1-5 (2006).
System 2: Enhanced electron transport through CdSe nanorods
orientationally ordered in the PV4P nanodomains of PS-b-P4VP copolymer
Major Achievement: The electron
mobilities of the CdSe/P4VP
nanodomains in the out-of-plane cases
were about eight times larger than
those in the in-plane cases.
Chung-Ping Li, Siao-Wei Yeh,Han-Chang Chang,Jung Y. Huang, and
Kung-Hwa Wei: “The Orientation of CdSe Nanorods Affects the
Electron Mobility of CdSe/P4VP Nanodomains Self-Assembled
within a Poly(styrene-b-4-vinylpyridine) Diblock Copolymer Thin
Film” -Small 2, 359-363 (2006).
System 3: Enhanced electron transport in a limited number of ordered ncAu constituents in the PV4P nanodomains of PS-b-P4VP copolymer
e-
Quasi 3D
e-
Quasi 1D
• Major Achievement: The electron transport rate via Coulomb
blockade process of nc-Au was found to be nearly an order of
magnitude greater than that of the random dispersion.
This sort of one-dimensional electronic behavior nicely demonstrates a
key element of using polymers, especially polymers with precise
nanostructures, to dictate properties of nanoparticles.
Chung-Ping Li, Ching-Mao Huang, Chia-Hao Wu, Kung-Hwa Wei, Jeng-Tzong Sheu, and Jung Y.
Huang, The Effect of Nanoscale Confinement on the Collective Electron Transport Behavior in Au
Nanoparticles Self-Assembled in a Nanostructured Poly(styrene-b-4-vinylpyridine) Diblock
Copolymer Ultra Thin Film, ADVANCED FUNCTIONAL MATERIALS (accepted, 2006).
II. Enhanced Light Emission
System 1: Thiophenol-Modified CdS Nanoparticles Enhance the
Luminescence of Benzoxyl Dendron Substituted Polyfluorene Copolymers
Major Achievement: Photoluminescence
and electroluminescence efficiencies of the
dendron-substituted copolyfluorenes are
dramatically enhanced by more than
doubled with a small percentage of
surface-modified CdS nanoparticles.
Chia-Hung Chou, Hsu-Shen Wang, Kung-Hwa Wei and Jung Y.
Huang: “Thiophenol-modified CdS nanoparticles enhance the
luminescence of benzoxyl dendron-substituted polyfluorene
copolymers” Advanced Functional Materials 16, 909 (2006).
System 2: Enhanced EL of Poly(2-methoxy-5-(20 ethylhexyloxy)-1,4phenylene vinylene) Films in the Presence of TiO2 Nanocrystals
•
Major Achievement: Doping TiO2 nano needles into MEH-PPV improves the
partial crystallization of MEH-PPV around TiO2, which in turn causes a
decrease in the hole barrier height (and an increase in hole mobility).
Therefore an enhanced EL efficiency was observed.
Chin-Cheng Weng, Chia-Hung Chou, Kung-Hwa Wei, and Jung Y. Huang: “Enhanced Electroluminescence of Poly(2methoxy-5-(20-ethylhexyloxy)-1,4- phenylene vinylene) Films in the Presence of TiO2 Nanocrystals” -Journal of Polymer
Research 13, 229 (2006).