Nanorings made of noble metals such as Au and Ag have attracted particular interest in plasmonic properties since they allow remarkable tunability of plasmon resonance wavelengths associated with their unique structural features. Unfortunately, most of the syntheses for Au nanorings involve complex procedures and/or require highly specialized and expensive facilities. Here, we report a seed-mediated approach for selective deposition of Au nanorings on the periphery of Pd seeds with the structure of an ultrathin nanosheet through the island growth mode. In combination with selective etching of Pd nanosheets, Au nanorings are eventually produced. We can control the outer diameter and wall thickness of the nanorings by simply varying the size of the Pd nanosheets and reaction time. By taking the advantage of this size controllability, the nanorings show tunable surface plasmonic properties in the near infrared (NIR) region arising from both the in-plane dipole and face resonance modes. Owing to their good surface plasmonic properties, the nanorings show substantially enhanced surface-enhanced Raman spectroscopy (SERS) performance for rhodamine 6G, and are therefore confirmed as good SERS substrates to detect trace amounts of molecules.

Strong coupling between semiconductor excitons and localized surface plasmons (LSPs) giving rise to hybridized plexciton states in which energy is coherently and reversibly exchanged between the components is vital, especially in the area of quantum information processing from fundamental and practical points of view. Here, in photoluminescence spectra, rather than from common extinction or reflection measurements, we report on the direct observation of Rabi splitting of approximately 160 meV as an indication of strong coupling between excited states of CdSe/ZnS quantum dots (QDs) and LSP modes of silver nanoshells under nonresonant nanosecond pulsed laser excitation at room temperature. The strong coupling manifests itself as an anticrossing-like behavior of the two newly formed polaritons when tuning the silver nanoshell plasmon energies across the exciton line of the QDs. Further analysis substantiates the essentiality of high pump energy and collective strong coupling of many QDs with the radiative dipole mode of the metallic nanoparticles for the realization of strong coupling. Our finding opens up interesting directions for the investigation of strong coupling between LSPs and excitons from the perspective of radiative recombination under easily accessible experimental conditions.Keywords: localized surface plasmon; photoluminescence; plexciton; quantum dot; Rabi splitting; silver nanoshell; strong coupling

We demonstrate the localized surface plasmon resonance enhanced silicon-rich silicon nitride based light-emitting devices by embedding the silver nanostructures between the silicon substrate and luminescent matrix. An about 30 times enhancement of external quantum efficiency is achieved by these inserted silver nanostructures. We attribute this distinct enhancement mainly to the improved back-scattering and carrier injection by the addition of silver nanostructures. The coupling between localized surface plasmons and excitons as well as the increase of light extraction via the surface roughening of ITO electrode also contributes to the enhancement of electroluminescence intensity and its efficiency.

We present all-inorganic solar cells fabricated from TiO2 nanorod array and semiconductor nanocrystals. CdSe or CdTe nanocrystals are drop-casted on TiO2 nanorod arrays to form TiO2 nanorod array/semiconductor nanocrystal hybrid structure. Thermal annealing is used to remove the organic molecules on the surface of the nanocrystals which could suppress electron transport, resulting in the morphological and structural change of the nanocrystals. For CdSe nanocrystals, p-type transparent semiconductor CuSCN is introduced as solid-state electrolyte to collect holes and TiO2/CdSe/CuSCN trilayer structure is adopted. While for CdTe nanocrystals, simpler TiO2/CdTe bilayer structure is adopted. Conversion efficiency of the two solar cells reaches to 0.21% and 0.07%, respectively. The results are a step towards development of high efficiency all-inorganic TiO2 nanorod array-based solar cells.Highlights► We fabricate two all-inorganic solar cells based on TiO2 nanorod arrays. ► CdSe or CdTe nanocrystals are used as absorbers. ► TiO2/CdSe/CuSCN trilayer structure and TiO2/CdTe bilayer structure are adopted.

Luminescent CuInS2 nanocrystals have been synthesized in dodecanethiol using air-stable precursors. The nanocrystals were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The optical properties of the CuInS2 nanocrystals can be controlled by changing the reaction conditions, such as reaction time, temperature, and addition of ligands. It was found that the steady-state photoluminescence spectrum of the close-packed CuInS2 nanocrystals on glass substrate peaked at longer wavelength than that of the colloidal ones and the close-packed nanocrystals possessed a shorter luminescence decay time. This behavior was explained on the basis of Förster resonant energy transfer due to the shorter distance between nanocrystals on substrate.Highlights► We synthesize luminescent CuInS2 nanocrystals in dodecanethiol. ► We control the optical properties of the CuInS2 nanocrystals. ► Energy transfer occurs in close-packed nanocrystals.

Quaternary CuInSSe nanocrystals have been synthesized by a colloidal route using commercially available materials. Oleylamine is used as the solvent and capping agent. It is proved that the nanocrystals are alloyed nanocrystals rather than a mixture of CuInS2 and CuInSe2 nanocystals. Furthermore, their formation is regarded to involve the nucleation of CuS and the subsequent reaction between CuS nuclei and remaining precursors. It is also found that the composition and structure of the nanocrystals can be influenced significantly by the reaction temperatures and time.Highlights► We synthesize quaternary CuInSSe nanocrystals in solution. ► Oleylamine acts as solvent and capping agent. ► Cu reacts faster with anions than In. ► Pure CuInSSe nanocrystals are obtained at temperatures above 180 °C.

The photoluminescence of silicon-rich nitride (SRN) film was coupled with the surface plasmon (SP) of Ag island film. It shows that the photoluminescence (PL) enhancement or quenching is strongly dependent on the excitation wavelength. When the excitation wavelength is near the SP resonance spectral region, the Ag islands act as a photo antenna, leading to the enhancement of the excitation cross-sections and therefore the photoemission enhancement. Furthermore, it is demonstrated that the metal island size also has an influence on the emission enhancement, but the enhancement is much more decided by the excitation wavelength than by the Ag island radiative scattering.

This letter describes a novel method of introducing controllable dislocations in silicon by electron irradiation. A corresponding dislocation-related light emitting diode with ∼1.6 μm emission at room temperature has been fabricated. A new affiliated peak of dislocation-related electroluminescence at ∼0.86 eV is observed. The current-dependent electroluminescence proves that the dislocation-related luminescence is derived from several dislocation-induced energy levels which have higher priority in recombination of the injected electrons and holes over the band-to-band recombination. Our work may provide an alternative approach for silicon-based light sources.Highlights► We reported a novel method of introducing controllable dislocations in silicon. ► A new sub-peak of dislocation-related electroluminescence at 0.86 eV is observed. ► The D1 emission has higher recombination priority over the band–band recombination. ► Our work may provide an alternative approach for silicon-based light sources.

A novel echinus-like hybrid structure composed of a SiO2@Ag core–shell and many silver nanorods was synthesized. These silver rods have a rare HCP structure, while the initial silver nuclei have a FCC structure. The rapid and free growth of silver nuclei resulted in the appearance of the HCP phase.

A simple one-step reduction method was explored to synthesize silver particles of different size. During synthesis, Polyvinylpyrrolidone (PVP) and CH2O were used as the protective agent and the reducing agent, respectively. It is found that the reaction parameters including the concentration of PVP and AgNO3, the amount of ammonia and the reaction temperature has great influence on the size and uniformity of silver particles. By careful tuning the reaction parameters, mono-disperse silver particles with the size of 40–2000 nm can be obtained controllably. It is considered that there were two growth modes: diffusional growth and aggregation.

Using a simple chemical reaction, a new nanostructure of silver, which we call a “flower-like silver structure”, is produced. The flower-like silver structure consists of a silver core and many rod-like tips protruding out in three dimensions. Besides common face-centered-cubic (FCC) phase of silver, there exists hexagonal-close-packed (HCP) phase in these tips. The appearance of HCP silver is the result of rapid growth of silver nuclei when using CH2O or C2H4O as the reducing agent. The formation of the rod-like tips is caused by the anisotropic growth determined by the HCP phase and the directing role of formic acid, which is the oxidation product of CH2O. It is also found that the concentration of reactants, the kind of reducing agents and the sequence of adding reactants can influence the morphology and phase constitution of the final products.

We synthesized SiO2@Ag core–shell particles with uniform and complete silver shells with an improved seed-mediated growth method. Silver nuclei produced on silica spheres with an electroless plating method served as nucleation sites for the growth of outer silver shells. By adjusting the Ag/SiO2 ratio, the thickness of silver shells was tuned, and the extinction peaks of SiO2@Ag particles shifted from visible to near-infrared (NIR) region. Comparing with previously reported methods, two important strategies were employed in the growth step of silver shells. First, polyvinylpyrrolidone (PVP) was added to control the isotropic growth of silver nuclei and improve the stability of core–shell particles. Second, the growth step of the outer silver shells was completed in a few seconds by increasing the reaction temperature and pH value. Furthermore, the SiO2@Ag core–shell particles were self-assembled into a monolayer, which served as a good SERS substrate.Graphical abstractUsing an improved seed-mediated growth method, complete silver shells were coated onto silica spheres.Highlights► SiO2@Ag particles with complete and smooth silver shells were prepared using an improved seed-mediated method. ► Rapid reaction in growth process of silver shells was considered to be very important. ► PVP was used to control the isotropic growth of silver nuclei and to avoid the aggregation of core–shell particles.

CdS and alloyed CdSxSe1−x nanocrystals were prepared by a simple noninjection method without nucleation initiators. Oleic acid (OA) was used to stabilize the growth of the CdS nanocrystals. The size of the CdS nanocrystals can be tuned by changing the OA/Cd molar ratios. On the basis of the successful synthesis of CdS nanocrystals, alloyed CdSxSe1−x nanocrystals can also be prepared by simply replacing certain amount of S precursor with equal amount of Se precursor, verified by TEM, XRD, EDX as well as UV–Vis absorption analysis. The optical properties of the alloyed CdSxSe1−x nanocrystals can be tuned by adjusting the S/Se feed molar ratios. This synthetic approach developed is highly reproducible and can be readily scaled up for potential industrial production.

Silicon-rich silicon nitride (SRSN) films were deposited on p-type silicon substrates using a conventional plasma-enhanced chemical vapor deposition (PECVD) system. Before deposition, silicon substrate was pre-treated by NH3 plasma in the PECVD system. And devices with metal–insulator–semiconductor (MIS) structure were fabricated using indium tin oxides (ITO) as anode and aluminum (Al) film as cathode. It was found that after 1100 °C annealing the electroluminescence (EL) intensity of NH3 plasma pre-treated MIS devices was increased greatly comparing with that of without NH3 plasma pre-treated devices. It is due to the passivation or reducing of interfacial states and nonradiative defects in SRSN films by the NH3 plasma pre-treatment and high-temperature annealing that enhanced the EL intensity of the SRSN MIS devices.

A novel echinus-like hybrid structure composed of a SiO2@Ag core–shell and many silver nanorods was synthesized. These silver rods have a rare HCP structure, while the initial silver nuclei have a FCC structure. The rapid and free growth of silver nuclei resulted in the appearance of the HCP phase.