Spectroscopy of Colloidal Quantum Dots of Controlled Shape and Size

Arjen Toni Dijksman 1
1 Semiconductor nanostructures
LPEM - Laboratoire de Physique et d'Etude des Matériaux
Abstract : Colloidal semiconductor nanocrystals, also called quantum dots, show properties of absorption and luminescence that find practical applications, such as biomedical imaging, light-emitting diodes and photovoltaics. In this thesis, we have synthesized CdSe quantum dots of different sizes and have improved their luminescent properties by growing a thick shell of CdS. We characterized these core-shell CdSe/CdS quantum dots with confocal fluorescence microscopy, correlating their photoluminescence with their cathodoluminescence and with their transmission electron microscopy images. This correlation was used to determine that the photoluminescence energy corresponds to the cathodoluminescence energy. We propose a model that describes the electron's path in a nanocrystal. This results in a linear equation that relates the energy of excitonic transitions to the size of the nanocrystal. This equation takes into account a phase jump and a time delay that corresponds to the electron bouncing at the surface. Probing this equation with experimental data reveals remarkable invariants that indicate that it can be applied to various materials in the 1D, 2D and 3D strong quantum confinement range.
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Submitted on : Thursday, October 24, 2013 - 12:27:10 PM
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Arjen Toni Dijksman. Spectroscopy of Colloidal Quantum Dots of Controlled Shape and Size. Micro and nanotechnologies/Microelectronics. Université Pierre et Marie Curie - Paris VI, 2013. English. ⟨pastel-00876357⟩

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