Hongyan Liang

High-Yield Uniform Synthesis and Microstructure-Determination of Rice-Shaped Silver Nanocrystals

High-yield uniform silver nanorices were synthesized by a facile polyol process without the introduction of shape-selected seeds. Nanorices exhibit two plasmon resonance peaks in the visible and near-infrared regions respectively due to their anisotropy. XRD patterns demonstrated the HCP phase coexists with the FCC phase in nanorices. The novel structure of nanorices was characterized by TEM study which shows that the intergrowth of FCC and a small amount of HCP phase, nanoscale FCC (111) twinning structure, and multimodulated structures formed by a complicated stacking sequence along the long axis direction. The correlation between morphology and microstructure is discussed.

Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films.

N-type metal oxide solar cells sensitized by infrared absorbing PbS quantum dots (QDs) represent a promising alternative to traditional photovoltaic devices. However, colloidal PbS QDs capped with pure organic ligand shells suffer from surface oxidation that affects the long term stability of the cells. Application of a passivating CdS shell guarantees the increased long term stability of PbS QDs, but can negatively affect photoinduced charge transfer from the QD to the oxide and the resulting photoconversion efficiency (PCE). For this reason, the characterization of electron injection rates in these systems is very important, yet has never been reported. Here we investigate the photoelectron transfer rate from PbS@CdS core@shell QDs to wide bandgap semiconducting mesoporous films using photoluminescence (PL) lifetime spectroscopy. The different electron affinity of the oxides (SiO2, TiO2 and SnO2), the core size and the shell thickness allow us to fine tune the electron injection rate by determining the width and height of the energy barrier for tunneling from the core to the oxide. Theoretical modeling using the semi-classical approximation provides an estimate for the escape time of an electron from the QD 1S state, in good agreement with experiments. The results demonstrate the possibility of obtaining fast charge injection in near infrared (NIR) QDs stabilized by an external shell (injection rates in the range of 110-250 ns for TiO2 films and in the range of 100-170 ns for SnO2 films for PbS cores with diameters in the 3-4.2 nm range and shell thickness around 0.3 nm), with the aim of providing viable solutions to the stability issues typical of NIR QDs capped with pure organic ligand shells.

Enormous Surface‐Enhanced Raman Scattering from Dimers of Flower‐Like Silver Mesoparticles

The surface-enhanced Raman scattering (SERS) of flower-like silver mesoparticle dimers with large hot areas is ≈10 to 100 times higher than the individual mesoparticles. The dependence of incident polarization illustrates that, even in the rough-surface mesoparticle dimer system, the coupling effect still dominates the SERS. More importantly, the micro-manipulator can be used to form dimers controlled with high SERS quality.

Chemically synthesized noble metal nanostructures for plasmonics

Abstract Noble metal nanostructures have drawn attentions of researchers in many fields due to their particular optical properties. Controlling the metal nanostructures’ size, shape, material, assembly, and surrounding environment can tune their unique plasmonic features that are important for practical applications. In this review, we firstly discuss some novel metal nanostructures synthesized through wet chemical methods and their fundamental plasmonic properties. Then, some applications of these chemically synthesized nanostructures in plasmonics are highlighted, including surface-enhanced Raman spectroscopy, plasmonic sensing, optical nanoantennas, and plasmonic circuitry. Plasmonic nanostructures provide the ways to manipulate light at the nanometer scale and open the prospects of developing nanophotonic devices for sensing and information technologies.