Bingjie Yang

Simple approach to wafer-scale self-cleaning antireflective silicon surfaces.

A simple approach to wafer-scale self-cleaning antireflective hierarchical silicon structures is demonstrated. By employing the KOH etching and silver catalytic etching, pyramidal hierarchical structures were generated on the crystalline silicon wafer, which exhibit strong antireflection and superhydrophobic properties after fluorination. Furthermore, a flexible superhydrophobic substrate was fabricated by transferring the hierarchical Si structure to the NOA 63 film with UV-assisted imprint lithography. This method is of potential application in optical, optoelectronic, and wettability control devices.

Tuning the Intensity of Metal‐Enhanced Fluorescence by Engineering Silver Nanoparticle Arrays

It is demonstrated that silver nanoparticle (SNP) arrays fabricated by combining nanoimprint lithography and electrochemical deposition methods can be used as substrates for metal-enhanced fluorescence, which is widely used in optics, sensitive detection, and bioimaging. The method presented here is simple and efficient at controlling the nanoparticle density and interparticle distance within one array. Furthermore, it is found that the fluorescence intensity can be tuned by engineering the feature size of the SNP arrays. This is due to the different coupling efficiency between the emission of the fluorophores and surface plasmon resonance band of the metallic nanostructures.

Biomimetic Antireflective Hierarchical Arrays

We report a simple method for the fabrication of biomimetic antireflective hierarchical arrays based on the combination of self-assembled polymer spheres and nanoimprint lithography (NIL). The hierarchical structures are fabricated by creating nanopillars on the microscale round protrusion arrays, which are similar to natural mosquito eyes consisting of combined micro- and nanostructures. The hierarchical arrays dramatically suppress the surface reflection from visible to near-infrared regions with an angle of incidence of up to 70°.

A Strategy for Patterning Conducting Polymers Using Nanoimprint Lithography and Isotropic Plasma Etching

Conducting polymer (CP) patterns with feature sizes of submicrometer to nanometer dimensions have attracted considerable attention due to their applications in light-emitting diodes (OLEDs), organic field effect transistors (OFETs), polymeric electrochromic devices, sensors, and biotechnology. In the last decade, the integration of two or more functional materials together is of increasing interest because materials with multiple components may exhibit integrative properties that single component materials do not possess. For example, CPs have been integrated with doping agent molecules or nanoparticles in order to improve properties or achieve multiplex character. Efforts to prepare conducting polymer patterns have mainly focused on photochemical patterning, microcontact printing (mCP), scanning probe lithography (SPL), electron-beam lithography (EBL), and dip-pen nanolithography. However, most of the techniques are incapable of integrating high resolution with high throughput. Nanoimprint lithography (NIL), which has gained significant attention due to its low cost and high throughput, is based on the mechanical deformation of the resist polymer by heating above the glass transition temperature (Tg) or by UVcrosslinking. By taking the CP or its mixture as resist layers and a subsequent reactive ion etching process, CPs have been patterned using NIL. However, NIL can only be applied on polymers that have a Tg or are UV-crosslinkable.

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.

Electrochemical deposition of silver nanoparticle arrays with tunable density.

We present a new approach to fabricate arrays of silver nanoparticles (SNPs) on predefined positions by means of electrochemical deposition (ECD) combined with nanoimprint lithography (NIL). The SNPs arrangement, especially the density can be tuned by varying the pattern design and the preparation conditions. By this approach, various arrays of SNPs with feature size down to submicrometer can be fabricated over several square centimeters on one substrate. The SNPs arrays can be readily extended to other conductive substrates, which have potential applications in detecting and sensing fields, such as surface-enhanced raman scatter.

Fabrication of TiO2 Arrays Using Solvent-Assisted Soft Lithography

We present a simple solvent-assisted soft lithography method to fabricate titania (TiO(2)) patterns. The dimensions of the TiO(2) features can be controlled by adjusting the concentration of the solution, the solvent evaporation duration, and temperature. This method may provide a facile route for fabricating large area patterns of metal oxide.

Au(I)-thiolate nanostructures fabricated by chemical exfoliation and their transformation to gold nanoparticle assemblies.

Chemical exfoliation method was applied to transform bulky assemblies of Au(I)-3-mercaptopropionate (MPA) coordination polymer (CP) to nanosheets and nanostrings using sodium citrate as an exfoliator. The exfoliation process and the structural characteristics of the Au(I)-MPA nanosheets and nanostrings were fully investigated by transmission electron microscopy, atomic force microscopy, UV-vis absorption spectroscopy, X-ray photoelectron spectroscopy and so on. As the structural rigidity and stability of the obtained Au(I)-MPA nanosheets, they are ideal precursors for fabrication of water soluble gold nanoparticle assemblies through progressive pyrolysis. This work provides a significant strategy toward the morphology regulation of CP nanostructures and will inspire further development of this research area.