Yinghui Sun

Single-Layer MoS2 Phototransistors

A new phototransistor based on the mechanically exfoliated single-layer MoS(2) nanosheet is fabricated, and its light-induced electric properties are investigated in detail. Photocurrent generated from the phototransistor is solely determined by the illuminated optical power at a constant drain or gate voltage. The switching behavior of photocurrent generation and annihilation can be completely finished within ca. 50 ms, and it shows good stability. Especially, the single-layer MoS(2) phototransistor exhibits a better photoresponsivity as compared with the graphene-based device. The unique characteristics of incident-light control, prompt photoswitching, and good photoresponsivity from the MoS(2) phototransistor pave an avenue to develop the single-layer semiconducting materials for multifunctional optoelectronic device applications in the future.

Flexible Colorimetric Detection of Mercuric Ion by Simply Mixing Nanoparticles and Oligopeptides

8 ] has been made over the past few decades. Such optical sensors are normally based on the simple measurement of the UV/Vis spectrum, fl uorescence spectrum, or colorimetry. Colorimetric detec-tion, which is visually and simply read out by the naked eye, is particularly attractive for point-of-use applications. What has limited such a colorimetric approach based on organic chromophoric probes is the narrow selectivity, solubility, and detection range. Recently, colorimetric detection based on Au nanopar-ticles (NPs) has drawn much attention,

Patterning of plasmonic nanoparticles into multiplexed one-dimensional arrays based on spatially modulated electrostatic potential.

We report a new strategy to pattern plasmonic nanoparticles into multiplexed one-dimensional arrays based on the spatially modulated electrostatic potential. The 32 nm Au nanoparticles can be simultaneously deposited on one chip with tunable interparticle distance by solely adjusting the width of the grooves. Furthermore, 32 and 13 nm Au nanoparticles can be selectively deposited in grooves of different widths on one chip. As a result, the surface plasmon absorption bands on the chip can be tuned depending on the interparticle distance or the particle size of multiplex 1D arrays, which could enhance the Raman scattering cross section of the adsorbed molecules and result in multiplex surface-enhanced Raman scattering (SERS) response on the chip. This strategy provides a general method to fabricate 1D multiplex arrays with different particle sizes and interparticle distances on one chip.

Electrophoretic Build-Up of Alternately Multilayered Films and Micropatterns Based on Graphene Sheets and Nanoparticles and their Applications in Flexible Supercapacitors

Graphene nanosheets and metal nanoparticles (NPs) have been used as nano-building-blocks for assembly into macroscale hybrid structures with promising performance in electrical devices. However, in most graphene and metal NP hybrid structures, the graphene sheets and metal NPs (e.g., AuNPs) do not enable control of the reaction process, orientation of building blocks, and organization at the nanoscale. Here, an electrophoretic layer-by-layer assembly for constructing multilayered reduced graphene oxide (RGO)/AuNP films and lateral micropatterns is presented. This assembly method allows easy control of the nano-architecture of building blocks along the normal direction of the film, including the number and thickness of RGO and AuNP layers, in addition to control of the lateral orientation of the resultant multilayered structures. Conductivity of multilayered RGO/AuNP hybrid nano-architecture shows great improvement caused by a bridging effect of the AuNPs along the out-of-plane direction between the upper and lower RGO layers. The results clearly show the potential of electrophoretic build-up in the fabrication of graphene-based alternately multilayered films and patterns. Finally, flexible supercapacitors based on multilayered RGO/AuNP hybrid films are fabricated, and excellent performance, such as high energy and power densities, are achieved.

Free-standing one-dimensional plasmonic nanostructures

The field of plasmonics has become one of the most interesting and active research areas in nanotechnology, enabling numerous fundamental studies and applications. The ability to tailor the size, shape, and environment of metal nanostructures is the key component for controlling the plasmonic properties of individual or aggregated nanostructures. In this feature article, a category of chemically nanofabricated, unique free-standing one-dimensional (1D) plasmonic nanostructures has been summarized. The dispersible plasmonic nanostructures were obtained in high yield with control over gap size and feature size. This ability was exploited to tune the emerging plasmonic properties overcoming the difficulties of other methods to do so, leading to applications in analytical detection, biological sensing, and nanoelectronics.

Synthesis of fivefold stellate polyhedral gold nanoparticles with {110}-facets via a seed-mediated growth method

New Type of Gold Nanoparticle: A new class of fivefold stellate polyhedral gold nanoparticles (FSPAuNPs) with {110} facets have been synthesized by a seed-mediated growth method without adding surfactant. The size of FSPAuNPs can be simply adjusted from nanoscale to microscale by varying the amount of seeds, which results in a shift of the surface plasmon resonance peak from the visible to the NIR range.

Towards active plasmonic response devices

Given the interdisciplinary challenges in materials sciences, chemistry, physics, and biology, as well as the demands to merge electronics and photonics at the nanometer scale for miniaturized integrated circuits, plasmonics serves as a bridge by breaking the limit in the speed of nanoscale electronics and the size of terahertz dielectric photonics. Active plasmonic systems enabling active control over the plasmonic properties in real time have opened up a wealth of potential applications. This review focuses on the development of active plasmonic response devices. Significant advances have been achieved in control over the dielectric properties of the active surrounding medium, including liquid crystals, polymers, photochromic molecules and inorganic materials, which in turn allows tuning of the reversible plasmon resonance switch of neighboring metal nanostructures.

Synergistic modulation of surface interaction to assemble metal nanoparticles into two-dimensional arrays with tunable plasmonic properties

A simple strategy based on the synergistic modulation of inter-particle and substrate-particle interaction is applied for the large-scale fabrication of two-dimensional (2D) Au and Ag nanoparticle arrays. The surface charge of the substrate is used to redistribute the double layer electric charges on the particles and to modulate the inter-particle distance within the 2D nanoparticle arrays on the substrate. The resultant arrays, with a wide range of inter-particle distances, display tunable plasmonic properties. It can be foreseen that such 2D nanoparticle arrays possess potential applications as multiplexed colorimetric sensors, integrated devices and antennas. Herein, it is demonstrated that these arrays can be employed as wavelength-selective substrates for multiplexed acquisition of surface-enhanced Raman scattering (SERS) spectra. This simple one step process provides an attractive and low cost strategy to produce high quality and large area 2D ordered arrays with tunable properties.

Semiconductive, one-dimensional, self-assembled nanostructures based on oligopeptides with π-conjugated segments

p Stacking between the s sheets: A newly designed p-conjugated peptide can be assembled into a one-dimensional nanostructure with strong p–p intermolecular electronic communication. A nanoelectronic device based on the achieved individual nanostructure was used to measure conductivity

Bio-inspired antireflective hetero-nanojunctions with enhanced photoactivity

A bio-inspired antireflective hetero-nanojunction structure has been fabricated by the hydrothermal growth of ZnO nanorods on silicon micro-pyramids. It has been shown that this structure suppresses light reflection more effectively resulting in a high photocurrent response and good charge separation simultaneously. The strategy provides a means to enhance solar energy conversion.