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Exciton Polariton Contribution to the Stokes Shift in Colloidal Quantum Dots
KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
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2011 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 13, 5286-5293 p.Article in journal (Refereed) Published
Abstract [en]

We study the exciton polariton contribution to the Stokes shift in colloidal quantum dots (QDs). By detailed quantum mechanical description of light-matter interaction and temporal analysis of incident electromagnetic field across the QD using the finite-difference time-domain method, we have shown that the optical excitation of an exciton in the QD and its coupling with the excitation radiation (i.e., exciton polariton) induce strong variations in the dielectric constant of the QD which contribute significantly to the Stokes shift and cause modifications 50 in the absorption spectrum that agrees well with experiments.

Place, publisher, year, edition, pages
2011. Vol. 115, no 13, 5286-5293 p.
Keyword [en]
CDS NANOCRYSTALS, DEPOSITION, ENERGY, FILMS, DARK
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-32622DOI: 10.1021/jp109608tISI: 000288885900014Scopus ID: 2-s2.0-79953677832OAI: oai:DiVA.org:kth-32622DiVA: diva2:411693
Note

QC 20110419

Available from: 2011-04-19 Created: 2011-04-18 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Exciton-plasmon interactions in metal-semiconductor nanostructures
Open this publication in new window or tab >>Exciton-plasmon interactions in metal-semiconductor nanostructures
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Semiconductor quantum dots and metal nanoparticles feature very strong light-matter interactions, which has led to their use in many photonic applications such as photodetectors, biosensors, components for telecommunications etc.Under illumination both structures exhibit collective electron-photon resonances, described in the frameworks of quasiparticles as exciton-polaritons for semiconductors and surface plasmon-polaritons for metals.To date these two approaches to controlling light interactions have usually been treated separately, with just a few simple attempts to consider exciton-plasmon interactions in a system consisting of both semiconductor and metal nanostructures.In this work, the exciton-polaritons and surface \\plasmon-polaritons are first considered separately, and then combined using the Finite Difference Time Domain numerical method coupled with a master equation for the exciton-polariton population dynamics.To better understand the properties of excitons and plasmons, each quasiparticle is used to investigate two open questions - the source of the Stokes shift between the absorption and luminescence peaks in quantum dots, and the source of the photocurrent increase in quantum dot infrared photodetectors coated by a thin metal film with holes. The combined numerical method is then used to study a system consisting of multiple metal nanoparticles close to a quantum dot, a system which has been predicted to exhibit quantum dot-induced transparency, but is demonstrated to just have a weak dip in the absorption.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. viii, 50 p.
Series
Trita-BIO-Report, ISSN 1654-2312 ; 2012:4
Keyword
plasmons, excitons, quantum dots, nanoparticles, FDTD, surface plasmon polaritons, QDIP, quantum dot infrared photodetector, polaritons
National Category
Nano Technology Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-93306 (URN)978-91-7501-301-5 (ISBN)
Public defence
2012-04-26, B2, Brinellvägen 23, KTH, Stockholm, 14:00 (English)
Opponent
Supervisors
Funder
Swedish e‐Science Research Center
Note

QC 20120417

Available from: 2012-04-17 Created: 2012-04-13 Last updated: 2013-04-09Bibliographically approved
2. Light manipulation in micro and nano photonic materials and structures
Open this publication in new window or tab >>Light manipulation in micro and nano photonic materials and structures
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Light manipulation is an important method to enhance the light-matter interactions in micro and nano photonic materials and structures by generating usefulelectric field components and increasing time and pathways of light propagationthrough the micro and nano materials and structures. For example, quantum wellinfrared photodetector (QWIP) cannot absorb normal incident radiation so thatthe generation of an electric field component which is parallel to the original incident direction is a necessity for the function of QWIP. Furthermore, the increaseof time and pathways of light propagation in the light-absorbing quantum wellregion will increase the chance of absorbing the photons.The thesis presents the theoretical studies of light manipulation and light-matter interaction in micro and nano photonic materials and structures, aiming atimproving the performance of optical communication devices, photonic integrateddevices and photovoltaic devices.To design efficient micro and nano photonic devices, it is essential to knowthe time evolution of the electromagnetic (EM) field. Two-dimensional and three-dimensional finite-difference time-domain (FDTD) methods have been adopted inthe thesis to numerically solve the Maxwell equations in micro and nano photonicmaterials and structures.Light manipulation in micro and nano material and structures studied in thisthesis includes: (1) light transport in the photonic crystal (PhC) waveguide, (2)light diffraction by the micro-scale dielectric PhC and metallic PhC structures(gratings); and (3) exciton-polaritons of semiconductor quantum dots, (4) surfaceplasmon polaritons at semiconductor-metallic material interface for subwavelengthlight control. All these aspects are found to be useful in optical devices of multiplebeam splitter, quantum well/dot infrared photodetectors, and solar cells.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. 72 p.
Series
Trita-BIO-Report, ISSN 1654-2312 ; 2012:13
Keyword
Photonic crystal, quantum dot, light-matter interaction
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-94081 (URN)978-91-7501-353-4 (ISBN)
Public defence
2012-06-01, FD51, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20120507Available from: 2012-05-07 Created: 2012-05-07 Last updated: 2012-05-07Bibliographically approved

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