Active Spectroscopy and Optical Imaging for Functional Materials with Engineered Architectures

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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.j
yhuang.idv.tw/teach.php.htm
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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

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Characterize Material System via Quantum Control
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Characterize Material System via Quantum Control
Phase
Field Amplitude
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Characterize Material System via Quantum Control

• Coherent control offers an opportunity to
  distinguish the coherent process from incoherent
  optical processes.

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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,
  333340 (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.

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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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Unmodulated Raman Spectrum of SSFLC
Lock-in Detected Raman Spectrum
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Raman Imaging with Photon Counting Lock-in
Detection

• 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 O.
• 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.

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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.

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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.

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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 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).
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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-vinylpyri
dine) Diblock Copolymer Thin Film -Small 2,
359-363 (2006).
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System 3 Enhanced electron transport in a
limited number of ordered nc-Au constituents in
the PV4P nanodomains of PS-b-P4VP copolymer
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• 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).

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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).
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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-ethylh
  exyloxy)-1,4- phenylene vinylene) Films in the
  Presence of TiO2 Nanocrystals -Journal of
  Polymer Research 13, 229 (2006).