We report a synthesis of highly luminescent (CdSe)ZnS composite quantum dots with CdSe cores ranging in diameter from 23 to 55 A. The narrow photoluminescence (fwhm ≤ 40 nm) from these composite dots spans most of the visible spectrum from blue through red with quantum yields of 30−50% at room temperature. We characterize these materials using a range of optical and structural techniques. Optical absorption and photoluminescence spectroscopies probe the effect of ZnS passivation on the electronic structure of the dots. We use a combination of wavelength dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, small and wide angle X-ray scattering, and transmission electron microscopy to analyze the composite dots and determine their chemical composition, average size, size distribution, shape, and internal structure. Using a simple effective mass theory, we model the energy shift for the first excited state for (CdSe)ZnS and (CdSe)CdS dots with varying shell thickness. Finally, we characterize the...

(CdSe)ZnS Core-Shell Quantum Dots - Synthesis and Characterization of a Size Series of Highly Luminescent Nanocrystallites

Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

12.2.2. Four-Wave Mixing (FWM) 4849 12.2.3. Dye Aggregation 4850 12.2.4. Optoelectronic Nanodevices 4850 12.3. Sensor 4851 12.3.1. Chemical Sensor 4851 12.3.2. Biological Sensor 4851 12.4. Catalysis 4852 13. Conclusion and Perspectives 4852 14. Abbreviations 4853 15. Acknowledgements 4854 16. References 4854 * Corresponding author E-mail: tpal@chem.iitkgp.ernet.in. † Raidighi College. § Indian Institute of Technology. 4797 Chem. Rev. 2007, 107, 4797−4862

Interparticle Coupling Effect on the Surface Plasmon Resonance of Gold Nanoparticles: From Theory to Applications

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Chemical strategies to design textured materials: from microporous and mesoporous oxides to nanonetworks and hierarchical structures.

Clearance properties of nano-sized particles and molecules as imaging agents: considerations and caveats.

Controlled synthesis and quantum-size effect in gold-coated nanoparticles.

Nanometer-size semiconductor particles coated with another semiconductor can exhibit unusual and interesting phenomena associated with the redistribution of the electron and hole wave functions. Using the band offsets and effective masses, the overlap of the electron and hole wave functions can be altered by changing the core radius of the particles. The theory can incorporate multiple shells, band bending, and charge effects. An efficient method for solving the equations is given.

Quantum confinement in semiconductor heterostructure nanometer-size particles.

Coated semiconductor nanoparticles (CSN) CdS/PbS in 60-80-A diameter were fabricated by Pb 2+ ions displacing Cd in Cd-S bonds on the surface of CdS single semiconductor nanoparticles (SSN) in CdS colloidal solution, although PbS has a different cubic crystalline structure than that of CdS. We use PVP (poly - (vinylpyrrolidonz)) as a stabilizing agent to control the size of CdS, PbS SSN, and CdS/PbS CSN. We investigated CdS/PbS nanoparticles' optical absorption and found that the excitation energy from the 1s hole state to the 1s electron state becomes smaller as the fraction of PbS shell in CdS/PbS CSN increases

Coated semiconductor nanoparticles; the cadmium sulfide/lead sulfide system's synthesis and properties

Metal‐coated, nanometer‐size particles are modeled with a realistic distribution of coating thicknesses. General expressions are given for the local‐field enhancement, absorption, and nonlinear optical response. In addition, heuristic arguments are used to determine the effects of a diffuse, rather than a sharp interface. The linear and nonlinear optical properties are discussed within the context of the effective medium theory for small volume fractions. An efficient method of solution is used with the flexibility to handle an arbitrary number of coatings.

Haoshen Zhou

Papers

Controlled synthesis and quantum-size effect in gold-coated nanoparticles.

Quantum confinement in semiconductor heterostructure nanometer-size particles.

Coated semiconductor nanoparticles; the cadmium sulfide/lead sulfide system's synthesis and properties

Enhanced optical properties of metal‐coated nanoparticles

Self‐Assembly of the Mesoporous Electrode Material Li3Fe2(PO4)3 Using a Cationic Surfactant as the Template