Semiconductor heterostructured seeded nanorods exhibit intense polarized emission, and the degree of polarization is determined by their morphology and dimensions. Combined optical and atomic force microscopy were utilized to directly correlate the emission polarization and the orientation of single seeded nanorods. For both the CdSe/CdS sphere-in-rod (S@R) and rod-in-rod (R@R), the emission was found to be polarized along the nanorod’s main axis. Statistical analysis for hundreds of single nanorods shows higher degree of polarization, p, for R@R (p = 0.83), in comparison to S@R (p = 0.75). These results are in good agreement with the values inferred by ensemble photoselection anisotropy measurements in solution, establishing its validity for nanorod samples. On this basis, photoselection photoluminescence excitation anisotropy measurements were carried out providing unique information concerning the symmetry of higher excitonic transitions and allowing for a better distinction between the dielectric and the quantum-mechanical contributions to polarization in nanorods.

The doping of colloidal semiconductor nanocrystals (NCs) presents an additional knob beyond size and shape for controlling the electronic properties. An important problem for doping with aliovalent elements is associated with resolving the location of the dopant and its structural surrounding within small NCs, an issue directly connected with self-purification. Here we used a postsynthesis diffusion-based doping method for introducing Cu impurities into InAs quantum dots. X-ray absorption fine structure (XAFS) spectroscopy experiments along with first-principle density functional theory (DFT) calculations were used to probe the impurity sites. The concentration dependence was investigated for a wide range of doping levels, helping to derive a self-consistent picture where the Cu impurity occupies an interstitial site within the InAs lattice. Moreover, at extremely high doping levels, Cu–Cu interactions are identified in the XAFS data. This structural model is supported by X-ray diffraction data, along with the DFT calculation. These findings establish the reproducibility of the diffusion-based doping strategy giving rise to new opportunities of correlating the structural details with emerging electronic properties in heavily doped NCs.

Infrared absorption measurements of amorphous and crystalline nanoparticles of GeTe reveal a localized surface plasmon resonance (LSPR) mode in the crystalline phase that is absent in the amorphous phase. The LSPR mode emerges upon crystallization of amorphous nanoparticles. The contrasting plasmonic properties are elucidated with scanning tunneling spectroscopy measurements indicating a Burstein-Moss shift of the band gap in the crystalline phase and a finite density of electronic states throughout the band gap in the amorphous phase that limits the effective free carrier density.

Hybrid nanoparticles combine two or more disparate materials on the same nanosystem and represent a powerful approach for achieving advanced materials with multiple functionalities stemming from the unusual materials combinations. This review focuses on recent advances in the area of semiconductor–metal hybrid nanoparticles. Synthesis approaches offering high degree of control over the number of components, their compositions, shapes, and interfacial characteristics are discussed, including examples of advanced architectures. Progress in hybrid nanoscale inorganic cage structures prepared by a selective edge growth mechanism of the metal onto the semiconductor nanocrystal is also presented. The combined and often synergistic properties of the hybrid nanoparticles are described with emphasis on optical properties, electronic structure, electrical characteristics, and light induced charge separation effects. Progress toward the application of hybrid nanoparticles in photocatalysis is overviewed. We conclude with a summary and point out some challenges for further development and understanding of semiconductor–metal hybrid nanoparticles. This progress shows promise for application of hybrid nanoparticles in photocatalysis, catalysis, optical components, and electronic devices.

The present invention provides and optical display device and a method for use in displaying an image. The optical display device comprises An optical display device comprising: at least one region of nanostructures operable as an optically active media, such that said nanostructures are responsive to input electromagnetic radiation to emit output electromagnetic radiation, and an arrangement of electrodes being configured and operable to be selectively addressable to create an external electric field to said at least one region of nanostructures, said region of nanostructures and said arrangement of electrodes defining together a pixel arrangement of said display device; said external electric field affecting said at least one region of nanostructures to selectively modulate emission of said output electromagnetic radiation, said output electromagnetic radiation being an output of at least one pixel element of the display device.

Fluorescence resonance energy transfer (FRET) involving a semiconductor nanoparticle (NP) acting as a donor, attached to multiple acceptors, is becoming a common tool for sensing, biolabeling, and energy transfer applications. Such nanosystems, with dimensions that are in the range of FRET interactions, exhibit unique characteristics that are related to the shape and dimensionality of the particles and to the spatial distribution of the acceptors. Understanding the effect of these parameters is of high importance for describing the FRET process in such systems and for utilizing them for different applications. In order to demonstrate these dimensionality effects, the FRET between CdSe/CdS core/shell NPs with different geometries and dimensionalities and Atto 590 dye molecules acting as multiple acceptors covalently linked to the NP surface is examined. Steady-state emission and temporal decay measurements were performed on the NPs, ranging from spherical to rod-like shaped systems, as a function of acceptor concentration. Changes in the NP geometry, and consequently in the distributions of acceptors, lead to distinctively different FRET behaviors. The results are analyzed using a modified restricted geometries model, which captures the dimensionality of the acceptor distribution and allows extracting the concentration of dye molecules on the surface of the NP for both spherical and elongated NPs. The results obtained from the model are in good agreement with the experimental results. The approach may be useful for following the spatial dynamics of self-assembly and for a wide variety of sensing applications.

We utilize single-molecule spectroscopy combined with time-correlated single-photon counting to probe the electron transfer (ET) rates from various types of semiconductor hetero-nanocrystals, having either type-I or type-II band alignment, to single-walled carbon nanotubes. A significantly larger ET rate was observed for type-II ZnSe/CdS dot-in-rod nanostructures as compared to type-I spherical CdSe/ZnS core/shell quantum dots and to CdSe/CdS dot-in-rod structures. Furthermore, such rapid ET dynamics can compete with both Auger and radiative recombination processes, with significance for effective photovoltaic operation.

Combining metal and semiconductor segments with well-defined morphologies on a single hybrid nanoparticle provides functionality benefiting from the joint and possibly also synergetic properties of the disparate components. We have recently reported the synthesis of a novel family of Ru nano-inorganic caged (NICed) copper(I) sulfide hybrid nanoparticles, which were grown through a mechanism of selective edge growth of the Ru on the copper(I) sulfide seeds. In this work we investigate the effect of reaction conditions on the Ru–Cu₂S products. There is an extraordinary sensitivity to reaction temperature in which four product structures were discovered upon varying the reaction temperature from 190 to 220 °C. The products changed from homogeneous nuclei of Ru along with the free Cu₂S seed at lower temperature, to Ru nano-inorganic caged copper(I) sulfide, to long thin Ru structures protruding from the seed surface at the higher temperature range. The resulting materials were imaged and characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), high-angle annular dark field-scanning TEM (HAADF-STEM), and powder Xray diffraction. Differential scanning calorimetric (DSC) analysis of the Cu₂S template nanoparticles revealed an endothermic peak at the specific temperature for selective edge growth of Ru, and was assigned to a surface change on the seed particle. Competition between homogeneous nucleation of the secondary material Ru and heterogeneous nucleation on the seed Cu₂S nanoparticle leading to a rich reaction landscape is discussed.