The assembling of semiconductor and metal ppm/Nanophotonics_Workshop/talks/ آ  The assembling

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  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    The assembling of semiconductor and metal nanocrystals

    Nikolai Gaponik, Alexey Shavel, Lehui Lu, Alexander Eychmüller

    Institute of Physical Chemistry and Electrochemistry, Technical University of Dresden

    01062 Dresden, GERMANY Institute of Physical Chemistry, University of Hamburg

    20146 Hamburg, GERMANY

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Content

    Introduction

    Synthesis and characterization of nanocrystals

    Formation of nanocomposites: •LbL assembly •Chemical conjugation •Solvent controlled precipitation •Electrostatic assembly and chemical plating •1D assemblies

    Conclusions

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Why nanocrystals?

    •Size-dependent physico-chemical properties

    •High photoluminescence quantum yields

    •Narrow emission (color purity)

    •Broad continous absorption bands

    •High stability against photodegradation

    •Solution processable photonics and optoelectronics

    •Specific: solubility in water and compatibility with common buffers at physiological concentrations

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Why assembly, self-assembly, templating?

    There is a lack of methods allowing controllable insertion of nano-objects (particles, molecules, composites, etc.) in photonic and optoelectronic micro(nano)structures

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    H2Te

    Al2Te3

    N2

    H2SO4

    H2Te, N2

    Cd(ClO4)2, R-SH

    Heating

    CdTe S

    SS

    S S

    R

    R

    R

    RR

    Main Goals: •stable, soluble, highly luminescent NCs •variable particle size •narrow size distribution •reproducibility •large-scale synthesis

    Nanocrystals: CdSe, CdTe, CdHgTe, HgTe, ZnSe, ...

    2.5 2.0 1.5 1.0

    500 1000 1500 2000 0.0

    0.5

    1.0

    750

    HgTeCdHgTeCdTe

    P L

    in te

    ns ity

    [a .u

    .]

    Wavelength [nm]

    Photon Energy [eV]

    Photoluminescence of NCs:

    Aqueous Synthesis of Nanocrystals

    J.Phys.Chem.B 2002, 106, 7177

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    NanoLett 2002, 2, 803

    CdTe/PLMA composite:

    0,0

    2,0x107

    4,0x107

    6,0x107

    8,0x107

    400 500 600 700 0,0

    0,1

    PL QE = 12%

    CdTe in water in toluene

    A bs

    or ba

    nc e

    [a .u

    .]

    Wavelength [nm]

    P L

    in te

    ns ity

    [c ou

    nt s]

    From water to toluene:

    Phase Transfer of Nanocrystals

    HgTe NCs in toluene:

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    LPPP/HgTe Infrared LED

    800 1000 1200 1400 1600 1800

    0,0

    0,2

    0,4

    0,6

    0,8

    1,0

    1,2 EL:

    0.0 V 10.0 V 12.0 V 15.0 V

    PL-red line

    P L,

    E L

    in te

    ns ity

    , a .u

    . Wavelength, nm

    X = CH3 R = C6H13

    R`= C10H21

    LPPP:

    Chem. Phys. Chem. 2004, 5, 1435

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Layer-by-layer (LbL) assembly of nanocrystals

    PDDA- poly(diallyldimethylammonium) chloride

    Assembly of PDDA/ZnSe film: PL and evolution of film absorption

    1. Positive polyelectrolyte

    2. Wash

    3. Negative nanoparticles

    4. Wash

    Procedures 1-4 can be repeated n-times

    =

    J.Phys.Chem.B 2004, 108, 5905

    300 400 500 600 0,00

    0,01

    0,02

    0,03

    0,04

    0,05

    A bs

    or pt

    io n

    Wavelength [nm]

    350 400 450

    Wavelength [nm]

    PL in

    te ns

    ity [a

    .u .]

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Transfer rate: (254ps)-1

    Appl. Phys. Lett. 2004, 84, 2904 Transfer rate: (71ps)-1

    Small 2005, 1, 392

    FRET in NC layers

    LbL films: Direct electrostatic assemblies:

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Selective LbL modification of photonic crystal heterolayers

    Scheme of LbL assembly and TEM image of modified polymer beads

    Day light

    UV light

    J.Appl.Phys. 2004, 95, 1029 phys.stat.sol. (a) 2003, 197, 662 Synth. Metals 2003, 139, 701

    300/240 nm hetero-opal. Bottom layer is modified with CdTe NCs

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    LbL- assembly and solvent controlled precipitation on colloidal particles

    1

    2

    3

    4

    5

    6

    7

    1. Polymer beads in

    water

    2. Adsorption of opposite

    charged polyelectrolyte

    molecules

    3. Centrifugation

    4a, 7a. Removing of supernatant. 4b, 7b. Particles redispersion in pure solvent

    (3 times)

    5. Adsorption of nanocrystals

    6. Centrifugation

    b

    b

    a

    a

    5µmAdv. Mater. 2001, 13, 1684

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Covalent linking of nanocrystals to the surfaces

    400 500 600 700 800 900 0.00

    0.02

    0.04

    0.06

    0.08

    0.10

    A bs

    or pt

    io n

    Wavelength [nm]

    0.0

    0.2

    0.4

    0.6

    0.8

    1.0

    N or

    m al

    iz ed

    P L

    in te

    ns ity

    [a .u

    .]

    SEM image of a single modified glass sphere

    Optical properties of modified microspheres

    ChemPhysChem 2005, 6, 449 Eur. J. Inorg. Chem. 2005, 3613

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Confocal image

    Modified colloidal particles TEM and HRTEM images

    Semicond. Sci. Technol. 2003, 18, 914 Appl. Phys. Lett. 2003, 83, 2539 J. Appl. Phys. 2004, 96, 6761.

    Coupling of NCs emission with the WGM oscillations of

    the microsphere:

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Phys. Rev. A 2004, 70, 051801 J. Appl. Phys. 2004, 96, 6761

    Photonic molecules

    D = 1.98 µm

    D = 1.99 µm

    WGM from single spheres:

    Coupled spheres:

    Controllable allignment:

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Individual modified colloidal particles - bright subwavelength light sources

    Confocal image of a 150 nm latex sphere modified with NIR-emitting

    (PL max ca. 1300nm) HgTe NCs

    Fluorescence of 468 nm latex beads modified with red- emitting (PL max 605 nm) CdTe NCs

    Adv. Mater. 2001, 13, 1684Appl. Phys. Lett. 2004, 84, 4732

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Beads modified with CdTe NCs for FRET-SNOM application

    Schematic of the setup

    SEM image sample labelled with acceptor

    The enhanced acceptor emission is detected to obtain an image with subwavelength resolution

    J.Phys.Chem.B 2004, 108, 14527

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Microencapsulation of Nanocrystals

    Core particles: MF, MnCO3

    Polyelectrolytes: Synthetic: PAH, PSS Biocompatible: Alginic acid sodium salt, Protamine sulfate, Dextrane sulfate, Chitosan.

    Nanocrystals: CdTe, CdHgTe, HgTe, emitting from 500 to 1100 nm, Fe3O4 magnetic particles

    Adv. Mater. 2002, 14, 879 Small 2005, 1, 194

    Langmuir 2004, 20, 1449 NanoLett. 2003, 3, 369

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    ChemPhysChem 2004, 5, 1600

    1D self-assemblies: Nanowires for Nanotechnology

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Gold-coated 3D ordered colloidal crystals Substrates for SERS

    Scheme of the fabrication procedure:

    Opal with assembled Au NCs: Chem. Mater. 2005, in press

  • First annual workshop in “Advances in Nanophotonics” Heraklion, Crete, Greece. 10th-13th October 2005

    Typical SiO2 template (a) and resulting Au/Pt hollow spheres (b,c)

    Macroporous Au/Pt structure:

    Disordered hollow Au/Pt spheres (a) and semispheres (b)

    Selective Fabrication of Ordered Bimetallic Nanostructures with Hierarchical Po