Photoluminescence from colloidal CdS–CdSe–CdS quantum wells
نویسندگان
چکیده
We report investigations of CdS–CdSe–CdS (core–well–shell) nanostructures by photoluminescence (PL) spectroscopy at temperatures between 77 and 300 K. PL intensity measurements show a transition from a pumprate-limited regime at low excitation intensity to the range determined by a spontaneous emission lifetime at a high excitation limit. PL intensity changes as a function of temperature. Also, the temperature dependences of the PL linewidth and PL peak energy are all determined experimentally. The PL linewidth is narrower for thicker quantum wells and becomes broader when the temperature increases owing to longitudinal-optical (LO) phonon scattering. The LO phonon scattering strength is around 30 meV, which is independent of the well thickness, and is much smaller than the value for bulk CdSe. © 2005 Optical Society of America OCIS codes: 160.2540, 300.6280.
منابع مشابه
Alternating layer addition approach to CdSe/CdS core/shell quantum dots with near-unity quantum yield and high on-time fractions.
We report single-particle photoluminescence (PL) intermittency (blinking) with high on-time fractions in colloidal CdSe quantum dots (QD) with conformal CdS shells of 1.4 nm thickness, equivalent to approximately 4 CdS monolayers. All QDs observed displayed on-time fractions > 60% with the majority > 80%. The high-on-time-fraction blinking is accompanied by fluorescence quantum yields (QY) clos...
متن کاملEnergy Transfer between Conjugated Colloidal Ga2O3 and CdSe/CdS Core/Shell Nanocrystals for White Light Emitting Applications
Figure S1. Photoluminescence spectra of CdSe/CdS nanocrystals (NCs) in (a) nanocrystal conjugate, linked with thioglycolic acid (TGA), upon correction for the contribution from Ga2O3 NC emission, (b) pure CdSe/CdS nanocrystal suspension, and (c) mixture of Ga2O3 and CdSe/CdS NCs without the TGA linker. The concentrations of CdSe/CdS NCs are identical in all panels, and are expressed in (a) as a...
متن کاملSynthesis and Characterization of Silica Coated CdSe/CdS Core/Shell Quantum Dots
A great deal of interest has been dawn on the colloidal chemistry based semiconductor nanocrysallites, also known as quantum dots (QDs). Because of the strong quantum confinement, quantum dots have unique size-dependent optical properties, which are much more superior to the conventional organic fluorescence materials. In addition, strong chemical resistant makes inorganic semiconductor QDs ide...
متن کاملMicrostructural and optical properties of CdSe/CdS/ZnS core-shell-shell quantum dots.
CdSe/CdS/ZnS core-shell-shell quantum dots (QDs) were synthesized by using a solution process. High-resolution transmission electron microscopy images and energy dispersive spectroscopy profiles confirmed that stoichiometric CdSe/CdS/ZnS core-shell-shell QDs were formed. Ultraviolet-visible absorption and photoluminescence (PL) spectra of CdSe/CdS/ZnS core-shell-shell QDs showed the dominant ex...
متن کاملSynthesis and Characterization of Water-dispersed CdSe/CdS Core-shell Quantum Dots Prepared via Layer-by-layer Method Capped with Carboxylic-functionalized Poly(Vinyl Alcohol)
The main goal of this work was to synthesize CdSe/CdS (core-shell) nanoparticles stabilized by polymer ligand using entirely aqueous colloidal chemistry at room temperature. First, the CdSe core was prepared using precursors and acid-functionalized poly(vinyl alcohol) as the capping ligand. Next, a CdS shell was grown onto the CdSe core via the layer-by-layer technique. The CdS shell was formed...
متن کامل