SPECTRAL AND DISTANCE CONTROL OF QUANTUM DOTS TO PLASMONIC

NANOPARTICLES INTERACTIONS

P. Viste, J. Plain, R. Jaffiol, A. Vial, P. M. Adam, P. Royer

ICD/UTT Troyes, Laboratoire de Nanotechnologie et d’Instrumentation Optique,

France

Introduction : to plasmonics !

. Surface Plasmon Polaritons on nanowaveguides : excitation, propagation, control and detection

main issues : lateral confinement and propagation distance

. Localized Surface Plasmons on metallic nanoparticles : coupling to quantum emitters

main issues : enhancement and directivity of the emission (weak coupling)

Introduction

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Fluorescence lifetime modification of Eu ions in front of a silver mirror

Drexhage K.H. progress in Optics (Wolf (E.) 1974

. Near field versus far field coupling

. Lifetime reduction is accompanied by photoluminescence quenching !

Introduction

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Fluorescence enhancement at the single molecule level

Enhancement of 1000

A. Kinkhabwala et al, Nature Phot. 3, 654 (2009)

Introduction

P. Pompa et al, Nature Nanotechnology 1, 128 (2006)

J. H. Song et al,Nano Lett. 5 (8), 1557 (2005)

Quantum Dots luminescence enhancement vs. quenching

on metal nanostructures

A systematic and parametric study is needed

S / S0 = (η/η0) (|p . Eloc|2/ |p· E0|2 )

Introduction

S0 : fluorescence signal without the metallic nanoparticles

S : fluorescence signal with the metallic nanoparticles

Eloc : local electric field can be enhanced through :

. Localized Surface Plasmon (LSP) Resonance

. lightning rod effect at sharp edges

. nanogaps

Quantum yield η0= r0/(nr0 + r0 )

η= r/(nr0 + r + nr)

Introduction

r : radiative relaxation rate of the system metallic nanoparticle /

moleculenr : nonradiative relaxation rate of the molecule in the metallic

nanoparticleIncrease or decrease of luminescence depends on interplay between Eloc, r , nr

and thus on the Nanoparticle geometry and LSP resonance!

Experiments :QDs on Plasmonic NanoParticles

(PNP)

Plasmonic NanoParticles fabrication

e-

e-beam lithography nanolithographied mask metal evaporation

lift off

The plasmon resonance is controlled over a wide spectral range

(depends on the height to diameter ratio): below and above the QD emission peak

Gold nanocylinders

350 400 450 500 550 600 650 700 7500

10

20

30

40

50

60

SpectredÕm̌ission

350 400 450 500 550 600 650 700 750 800 850 900 9500,0

0,1

0,2

0,3

inte

nsitˇ

(u.

a.)

longueur d'onde (nm)

Absorption des nanocristaux semi-conducteurs

Absorption and emission spectraof CdTe/CdS/TOPO Quantum Dots

Absorption of the QD

Emission of the QD : 665 nm peakTOPO organic ligands

CdS shell

CdTe core

Wavelength (nm)

No LSP resonance at the excitation wavelength (405 nm) !

Measured QD photoluminescence on different PNP patterns

140nm

130nm

Bare QD

80nm

Quantum dots in PMMA

Collection area =1μ2

Excitation wavelength

: 405 nm

PL modification factor F as a function of the PNP diameter for gold and silver

Enhancement of the PL by a factor 2.6

Photoluminescence enhancement and quenching

PNP diameter (nm)

Modification factor of QD luminescencefor gold nanocylinders

Enhancement when the emission of the QD (665 nm)

is close to the LSP resonance

600 620 640 660 680 700 720 7400,0

0,5

1,0

1,5

2,0

2,5

inte

nsi

té n

orm

alis

ée

(u

. a.)

longueur d'onde plasmon (nm)

Luminescence en l'absence des nano-cylindres

Wavelength (nm)

Luminescence in absence of the nanocylinders

F

Discussion

• Resonant behaviour of the QD photoluminescence

when coupled to gold nanocylinders : increase of

η

• Enhancement occurs when the emission is blue shifted

(40 nm)

with respect to the LSP resonance

LSP resonance is obtained through plane wave

excitation

PNP is excited by the near-field of the emission dipole- Colas des Francs, G, et al. Optics Express, 16 , 22, 17654-17666 (2008)

- Bharadwaj, P., Novotny, Optics Express, 15 , 21, 14266-14274 (2007).

Interdistance QD-PNP influence

PL modification as a function of the interdistance R

PNP Enhancement PNP Quenching

R decreasing

R decreasing

PL modification factor F as a function of the MNP - QD interdistance for gold PNP

of 80nn, 100nm, 120nm, 130nm, 140nm and 160nm.

PL modification as a function of the interdistance

QD - MNP coupling efficiency as a function of the interdistance R.

E(R) shows a R-6 dependency

• Quenching : non radiative energy transfer from the QD

to the PNP :

- if R > > PNP diameter : dipole - dipole coupling : 1/r6

law

- if R < < PNP diameter : plane - dipole coupling : 1/r3

law

QD Emitter couples to a protrusion on the PNP !

Discussion

M. Thomas, J.-J. Greffet, R. Carminati, J. R. Arias-GonzalezAppl. Phys. Lett. 85, 3863 (2004)

• Enhancement : two types

- Coherent interference of radiations of the emission dipole

and the induced dipole in the PNP : 1/r3 law

- Energy transfer from the emission dipole to the PNP

followed by radiation of the PNP : 1/r6 law

Discussion

M. Thomas, J.-J. Greffet, R. Carminati, J. R. Arias-GonzalezAppl. Phys. Lett. 85, 3863 (2004)

Conclusions

•Control of enhancement or quenching of the PL through the plasmonic nanoparticle size and resonance

•Near field coupling of the QD to the PNP accompanied by non radiative energy transfer

P. Viste et al. ACS Nano. 4, 759 (2010)

Outlooks •PNP induced modification and control of the luminescence radiation pattern : nanoantenna concept

•Huge enhancements of luminescence with plasmonic nanocavities

•Single QD intensity and lifetime measurements

•Complete model of the emitter/PNP system