active spectroscopy and optical imaging for functional materials with engineered architectures jung...
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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 problemthe inverse problem, i.e., how tohow to retrieve information of the system dynamicsretrieve information of the system dynamics from from the knownthe known
optimal pulseoptimal pulse ---- Active Spectroscopy
Characterize Material System via Quantum Control
SLM
Grating Grating
spectrometer
Objective lens
sample
Beam splitter
XY scanning stage
Input pulses
Characterize Material System via Quantum Control
FieldAmplitude
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.
optimized
anti-optimized
Important Question: What is the characteristic frequency among these binding nano objects?
Future Development: Quantum-control technique for probing molecular recognition mechanism of Biomolecules.
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.
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7000
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9000
Inte
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ity
(a
rb.
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its
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Wavenumber (cm-1)
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4800 ampl. phase
Wavenumber (cm-1)
Am
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1610
15051446
1326
1118(c)
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as
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eg
ree
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Unmodulated Raman Spectrum of SSFLC
Lock-in Detected Raman Spectrum
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3200 ampl. phase
Frequency (Hz)
Am
plit
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e(ar
b. u
nit
s)
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Ph
ase (deg
rees)
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Frequency (Hz)
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The amplitude (filled circles) and the phase (open squares) of a phase-resolved 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.
Raman Imaging with Photon Counting Lock-in Detection
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.
p-Type
n-Type
+_ _ _ _
_ __
_
+
++ + +
++
pn-junction
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 Self-Assembled 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 nc-
Au constituents in the PV4P nanodomains of PS-b-P4VP copolymer
Quasi 3D Quasi 1D
e-e-
• 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
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 1: Thiophenol-Modified CdS Nanoparticles Enhance the Luminescence of Benzoxyl Dendron Substituted Polyfluorene Copolymers
System 2: Enhanced EL of Poly(2-methoxy-5-(20 ethylhexyloxy)-1,4-phenylene 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(2-methoxy-5-(20-ethylhexyloxy)-1,4- phenylene vinylene) Films in the Presence of TiO2 Nanocrystals” -Journal of Polymer Research 13, 229 (2006).