Fluorescent semiconductor nanocrystals (quantum dots) have the potential to revolutionize biological imaging, but their use has been limited by difficulties in obtaining that are biocompatible. To address this problem, we encapsulated individual phospholipid block–copolymer micelles and demonstrated both vitro vivo imaging. When conjugated DNA, nanocrystal-micelles acted as fluorescent probes hybridize specific complementary sequences. Moreover, when injected into Xenopus embryos, were...

Well documented procedures to grow zero-dimensional systems, dots, and one-dimensional wires tubes, as colloidal particles in solution have been reported. In contrast, there are no methods of preparation that yield optically active two-dimensional soluble particles. Yet, ultrathin films (quantum wells) II−VI III−V semiconductors epitaxially grown on substrates by molecular beam epitaxy for example proven extremely useful both fundamental studies a wealth applications optoelectronics. We show...

Semiconductor quantum dots (QDs) could significantly impact the performance of biomedical near-infrared (NIR) imaging by providing fluorescent probes that are brighter and more photostable than conventional organic dyes. However, toxicity components NIR emitting II-VI IV-VI QDs have been made so far (Cd, Hg, Te, Pb, etc.) has remained a major obstacle to clinical use QDs. Here, we present synthesis CuInS(2)/ZnS core/shell in ( approximately 800 nm) with good yield stability even after...

We study the formation of colloidal CdSe nanoplatelets using both tansmission electron microscopy (TEM) and spectroscopic analysis. show that platelets form by continuous lateral extension small (<2 nm) nanocrystal seeds. The nanoplatelet thickness is fixed seed dimension remains constant during platelet formation. dimensions can be tuned additional precursor injection. Absorption fluorescence analysis as they continuously extend laterally confirms a transition from 3D to 1D confined...

We have recently synthesized atomically flat semiconductor colloidal nanoplatelets with quasi 2D geometry. Here, we show that core/shell can be obtained a geometry is conserved. The epitaxial growth of the shell performed at room temperature. report detailed synthesis CdSe/CdS and CdSe/CdZnS structures different thicknesses. characterized both spectroscopically structurally. In particular, structure appears very clearly on high-resolution, high-angle annular dark-field transmission electron...

We collect and resolve spectrally temporally the photoluminescence of single CdSe nanoplatelets. The emission intensity nanoplatelets at room temperature shows ON OFF periods with a usual blinking statistics, while 20 K, their can be extremely stable in time. At temperature, spectra are similar to ensemble measurements full width half-maximum 40 meV. we obtain resolution-limited spectral line (<0.4 meV). fluorescence lifetime decreases when reach 200 ps K. This shortening is concomitant an...

When compared to standard colloidal nanocrystals, individual CdSe-CdS core-shell nanocrystals with thick shells exhibit strongly reduced blinking. Analyzing the photon statistics and lifetime of on state, we first demonstrate that bright periods correspond single emission a fluorescence quantum efficiency monoexcitonic state greater than 95%. We also show low intensity emitting are not dark but grey 19%. From these measurements, deduce radiative (45 ns) Auger (10.5 state.

CONSPECTUS: Semiconductors are at the basis of electronics. Up to now, most devices that contain semiconductors use materials obtained from a top down approach with grown by molecular beam epitaxy or chemical vapor deposition. Colloidal semiconductor nanoparticles have been synthesized for more than 30 years and their synthesis is becoming mature enough these started be incorporated into devices. An important development recently took place in field colloidal quantum dots two-dimensional...

We present the synthesis and optical properties of a new type two-dimensional heterostructure: core/crown CdSe/CdS nanoplatelets. They consist CdSe nanoplatelets that are extended laterally with CdS. Both core CdS crown dimensions can be controlled. Their thickness is controlled at monolayer level. These novel nanoplatelet-based heterostructures have spectroscopic similar to or closer quantum dots, depending on lateral size.

The first functional light‐emitting diodes (LEDs) based on quasi 2D colloidal core/shell CdSe/CdZnS nanoplatelets (NPLs). solution‐processed hybrid devices are optimized with respect to their electroluminescent characteristics, first, by improving charge injection through exchanging the as‐synthesized NPL long‐chain ligands shorter ones such as 3‐mercaptopropionic acid, and second, comparing different hole‐transporting layers. NPL‐LEDs exhibit a maximum luminance of 4499 cd m ‐2 external...

Free standing two-dimensional materials appear as a novel class of structures. Recently, the first colloidal heterostructures have been synthesized. These core/shell nanoplatelets are step toward quantum wells. Here, we study in detail spectroscopic properties this generation nanoparticles. We show that CdSe/CdZnS with 80% yield can be obtained. The emission time trace single exhibits reduced blinking compared to core two level trace. At cryogenic temperatures, these close 100% and stable A...

Abstract Wavefunction engineering using intraband transition is the most versatile strategy for design of infrared devices. To date, this nevertheless limited to epitaxially grown semiconductors, which lead prohibitive costs many applications. Meanwhile, colloidal nanocrystals have gained a high level maturity from material perspective and now achieve broad spectral tunability. Here, we demonstrate that energy landscape quantum well dot photodetectors can be mimicked mixture mercury selenide...

Infrared thermal imaging devices rely on narrow band gap semiconductors grown by physical methods such as molecular beam epitaxy and chemical vapor deposition. These technologies are expensive, infrared detectors remain limited to defense scientific applications. Colloidal quantum dots (QDs) offer a low cost alternative detector combining inexpensive synthesis an ease of processing, but their performances so far limited, in terms both wavelength sensitivity. Herein we propose new generation...

A new and efficient procedure for ligand exchange on core−shell fluorescent nanocrystals is reported. The process involves the reaction of carbon disulfide with a containing an amino group. resulting dithiocarbamate strongly bound to surface quantum dots leading secure coating nanoparticle. strategy was applied aqueous transfer dots.

We have developed a novel surface coating for semiconductor quantum dots (QDs) based on heterobifunctional ligand that overcomes most of the previous limits these fluorescent probes in bioimaging applications. Here we show QDs capped with bidentate zwitterionic dihydrolipoic acid−sulfobetaine (DHLA−SB) ligands are favorable alternative to polyethylene glycol-coated nanoparticles since they combine small sizes, low nonspecific adsorption, preserved optical properties, and excellent stability...

We experimentally demonstrate the control of spontaneous emission rate and radiation pattern colloidal quantum dots deterministically positioned in a plasmonic patch antenna. The antenna consists thin gold microdisk separated from planar layer by few tens nanometers thick dielectric layer. emitters are shown to radiate through entire highly directional vertical pattern. Strong acceleration is observed, depending on geometry. Considering double dipole structure emitters, this corresponds...

We report the synthesis of CdSe/CdS semiconductor core/shell nanocrystals with very thick (5 nm) CdS shells. As in case core CdSe nanocrystals, we show that a thick-shell structure can be synthesized either pure wurtzite (W) or zinc-blende (ZB) crystal structure. While growth is quite straightforward, observe shell on cores more difficult and leads to wurtzite/zinc-blende polytypism when primary amines are present during formation. Using absorption spectra analysis differentiate zinc blende...

Near-infrared (NIR) semiconductor quantum dots (QDs) represent promising fluorescent probes for biological and biomedical imaging. CuInSe2 is a good candidate these applications due to its bandgap in the near-infrared reduced toxicity of components compared other NIR QD materials (CdTe, CdHgTe, PbS, etc.). Here we present simple one-pot synthetic route without injection make sphalerite Cu−In−Se core Cu−In−Se/ZnS core/shell QDs. We show that photoluminescence (PL) resulting QDs can be tuned...

We have synthesized atomically flat CdSe/CdTe core/crown nanoplatelets (NPLs) with thicknesses of 3, 4, and 5 monolayers fine control the crown lateral dimensions. In these type-II NPLs, charges separate spatially, electron wave function is localized in CdSe core while hole confined CdTe crown. The exciton's recombination occurs across heterointerface, as a result their spatially indirect band gap, an important emission red shift up to near-infrared region (730 nm) observed long fluorescence...