Silica microspheres coated with a silica or titania shell containing fluorescent semiconductor nanocrystals are described. Since the coating process does not affect monodispersity of microspheres, defined size and emission wavelength, potentially useful for biological applications, can be fabricated. The Figure shows 100 nm diameter blue-light-emitting 500 red-light-emitting circulating in brain mouse.

Spherical whispering-gallery-mode lasers employing CdSe/ZnS semiconductor nanocrystals (see Figure, inset scale bar: 15 μm) are assembled on a substrate using simple, robust spin-coating fabrication method. The flexibility to choose the size of microsphere template and emission wavelength allows for observation single-mode lasing. At higher excitation intensities, lasing from multiexcitonic states is also observed.

We demonstrate tunable room-temperature amplified spontaneous emission and lasing from blue-emitting core-shell CdS∕ZnS nanocrystals (NCs) stabilized in a sol-gel derived silica matrix. Variable stripe length measurements show that these NC-silica composites have modal gain of ∼100cm−1 at room temperature. Coating microspheres with composite film via facile process resulted uniform resonators exhibit over long periods continuous excitation. This work opens up spectral window for tunable,...

Ultralow-threshold two-photon pumped amplified spontaneous emission (2ASE) and lasing in seeded CdSe/CdS nanodot/nanorod heterostructures is demonstrated for the first time. Such allow independent tunability of absorption (2PA) cross-section (σ2) through varying CdS rod size, that wavelength CdSe dot size. With an enhanced σ2, 2ASE these achieved with ultralow threshold fluence ∼1.5 mJ/cm2, which as much one order less than required spherical semiconductor NCs. Importantly, by exploiting...

Abstract Although multiphoton-pumped lasing from a solution of chromophores is important in the emerging fields nonlinear optofluidics and bio-photonics, conventionally used organic dyes are often rendered unsuitable because relatively small multiphoton absorption cross-sections low photostability. Here, we demonstrate highly photostable, ultralow-threshold biexcitonic colloidal CdSe/CdS nanoplatelets within cuvette-based Fabry–Pérot optical resonator. We find that surprisingly exhibit an...

Wet-chemically synthesized cesium lead halide nanoparticles have many attractive properties that make them promising as optical gain media, but generally suffer from poor stability under ambient conditions and an threshold is widely believed to be dictated by the need for biexcitons. These it impractical such particles utilized media given undergo repeated stimulated emission processes at above-threshold pump intensities over long periods of time. We demonstrate surface treatment CsPbBr3...

This communication describes a long (1 cm), laser-pumped, liquid core−liquid cladding (L2) waveguide laser. device provides simple, high intensity, tunable light source for microfludic applications. Using core solution of 2 mM rhodamine 640 perchlorate, optically pumped by frequency-doubled Nd:YAG laser, we found that the threshold lasing was as low 22 μJ (16-ns pulse length) and had slope efficiency up to 20%. The output wavelength over 20-nm range changing ratio solvent components...

Multifunctional peptide−polymer hybrid materials have been applied as efficient and biocompatible quantum-dot coating materials. Significant pH responsiveness (e.g., an influence of the on quantum yields peptide−polymer/QDs) was found is attributed to conformational rearrangements peptide backbone.

Sowing the seeds: The growth of Au and Ag2S nanoparticles at distinct positions on CdSe-seeded CdS heterostructured nanorods can be precisely controlled by variations in concentration Ag precursors, respectively. ability to direct lead "Janus-type" structures where is located more reactive end nanorod, whilst other (see picture; CdSe dark blue, light yellow, gray).

We use transient photoluminescence to spectrally resolve the emission from 1, 2, and 3 electron-hole pairs states in $\mathrm{CdSe}$ colloidal quantum dots with radii ranging between 2.3 $5.2\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. The power dependence of triexciton, biexciton single exciton intensities are reported. incorporate $\mathrm{CdSe}∕\mathrm{ZnS}$ core-shell nanocrystals into a ${\mathrm{TiO}}_{2}$ host matrix observe simultaneous amplified spontaneous...

We introduce a facile approach for the selective deposition of metals on Au-tipped CdSe-seeded CdS nanorods that exploits transfer electrons from to Au tips upon UV excitation. This light-induced method was used Pd under mild conditions, which produced Pd/Au alloyed tip while preserving rest semiconductor nanoarchitecture. The highly site-selective extended Fe, yielding monodispersed, structurally complex core/Fe(x)O(y) hollow shell-tipped nanorods. These well-defined rods were found exhibit...

We fabricated a single active layer quantum dot light-emitting diode device based on colloidal CdSe (core)/CdS (arm) tetrapod nanostructures capable of simultaneously producing room temperature electroluminesence (EL) peaks at two spectrally distinct wavelengths, namely, ∼500 and ∼660 nm. This remarkable dual EL was found to originate from the CdS arms core architecture, which implies that radiative recombination injected charge carriers can independently take place spatially regions...

Core/shell tetrapods synthesized from CdSe and CdTe exhibit a type II band offset that induces separation of charge upon photoexcitation localizes carriers to different regions the tetrahedral geometry. CdSe/CdTe nanocrystals immobilized on oleylamine‐functionalized reduced graphene oxide (rGO) sheets can be homogeneously mixed with an organic dye (PCDTBT) form donor–acceptor dispersed heterojunctions high power conversion efficiency ∼3.3% in solar cell devices. The near‐IR light absorbing...

Quasi-two-dimensional colloidal nanoplatelets (NPLs) have recently emerged as a class of semiconductor nanomaterials whose atomically precise monodisperse thicknesses give rise to narrow absorption and emission spectra. However, the sub-picosecond carrier dynamics NPLs at band edge remain largely unknown, despite their importance in determining optoelectronic properties these materials. Here, we use combination femtosecond transient spectroscopy nonadiabatic molecular simulations investigate...

Multiple-wavelength distributed-feedback lasers are made from multilayered composites by utilizing the solution-processing ease of cadmium selenide semiconductor nanocrystals and soft lithography. The Figure shows three types emission obtained such structures across a wide range visible spectrum: fluorescence (dotted lines), amplified spontaneous (dashed feedback-induced lasing (solid lines).

We report simultaneous amplified spontaneous emission from two different multiexcitonic transitions −1Se–1S3∕2 and 1Pe–1P3∕2− of colloidal CdSe nanocrystals (NCs) stabilized in high volume fraction titania matrices. Two-state lasing both is achieved a surface-emitting distributed feedback NC laser. Variable stripe length measurements show that the gain 1Pe–1P3∕2 transition approximately twice for 4.2nm radius CdSe∕ZnS core-shell NCs.

We describe a surfactant-driven method to synthesize highly monodisperse CdSe-seeded CdS nanoheterostructures with conelike, tapered geometries in order examine the effects of shape on location-specific deposition Au under ambient conditions. Although preferential metal at surface defect sites are generally expected, we found suprisingly that growth side facets linear and branched structures was significantly suppressed. Further investigation revealed this be due efficient electrochemical...

Size-dependent three-photon absorption (3PA) and three-photon-excited photoluminescence (PL) of CdSe/CdS nanorod heterostructures have been investigated using Z-scan upconversion PL techniques with 150 fs laser pulses at 1300 nm. The from these rods shows clear cubic power dependence, the 3PA cross section (σ3) was found to be as high 1.5 × 10–75 cm6 s2 photon–2 for 39 nm long rods, which is 2–4 orders magnitude larger than those previously reported spherical semiconductor nanocrystals under...

We describe a surfactant-driven method to synthesize highly monodisperse CdSe-seeded CdS tetrapods with differing arm lengths and diameters in order examine their effects on self-assembly. exploited the phenomena of weak- strong-binding capping groups tune length diameter uniform shape achieved >95% yield. Afterward, we utilize these particles overcome some key problems assembly anisotropic shaped particles. Intriguingly, found that certain pack like fishbone chains, which was greatly...

Wet-chemically synthesized CdSe seeded CdS nanotetrapods incorporated into silica matrices have been explored as high performance nanocrystal-based optical amplifiers. Varying the physical dimensions of tetrapods allowed for room temperature biexcitonic amplified spontaneous emission (ASE) at wavelengths corresponding to either core or arms, while higher pump intensities resulted in ASE from a excited state. These results collectively indicate that such heterostructured can facilitate...

We introduce a facile and robust methodology for the aggregation-free aqueous-phase synthesis of hierarchically complex metal-semiconductor heterostructures. By encapsulating semiconductor nanostructures within porous SiO(2) shell with hollow interior, we can isolate each individual particle while allowing it access to metal precursors subsequent growth. illustrate this by Pt deposition on CdSe-seeded CdS tetrapods, which found be facilitated via surprising formation thin interfacial layer...

We report the synthesis of colloidal 2D PbS nanoplates with residual Cu2S domains via a partial cation-exchange process involving Pb2+ and presynthesized hexagonal an average thickness ∼3 nm edge lengths ∼150 nm. Different from previously reported nanosheets whose basal planes are ±{100}PbS, our approach yields ±{111}PbS, which was theoretically predicted to have better surface ligand passivation. Subsequently, we found that showed improved stability did not suffer severe aggregation despite...

We present a method to separately tune the multiphoton absorption (MPA) and excited photoluminescence using semiconductor core/enlarged-shell quantum dots (QDs), where enlarged shell greatly enhances MPA cross-sections while varying core size facilitates emission wavelength selectivity. Following two-photon (2PA) primarily in ultrafast charge-carrier localization core, luminescence occurs. exemplify validity of this with CdSe/CdS nanorod heterostructures find that 2PA cross-section is...