integration-light-trapping-silver-nanostructures-hydrogenated

Integration of Light Trapping Silver Nanostructures in Hydrogenated Microcrystalline Silicon Solar Cells by Transfer Printing

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly ...

National Institute of Advanced Industrial Science and Technology, Koriyama, Fukushima, Japan

Formylpeptide receptors are well-characterized receptors which participate in host defense responses of neutrophils. We designed and synthesized chemotactic peptide analog with p-benzoylphenylalanine (Bpa) and biotin to probe structural and mechanistic aspects of peptide-receptor interaction. These peptides possess biological activities which were dependent upon spacer residue length of and Bpa position. The covalent photoaffinity label was detected by Streptavidine-blot, which was inhibited by the parent peptide.

Synthesis of chemotactic peptide analogs with a photoaffinity cross-linker as new probes for analysis of receptor-ligand interaction.

A tryptic [EC 3.4.21.4] digestion assay of 2-aminoisobutyric acid (Aib)-containing peptides was carried out to investigate the effect of alpha,alpha-dialkyl amino acid residues on the protease resistance. The introduction of Aib residues to the P1' positions exhibited a 19-fold higher protease resistance than the peptide with Aib residues introduced to the P2 position or the non-Aib peptide. The peptide having Aib residues introduced to the P1' and P2 positions resulted in complete resistance.

Effect of alpha,alpha-dialkyl amino acids on the protease resistance of peptides.

Even with intensive research, air-stable blue light emission from silicon nanocrystals (Si-ncs) at room temperature still remains a challenge. We show that stable and blue-luminescent Si-ncs can be produced by laser-generated plasma (nanosecond-pulsed excimer laser) confined in water. These Si-ncs exhibit quantum confinement effect due to their size and are produced with an environmentally compatible process. The effect of aging for several weeks in water and air on blue Si-ncs emission properties is compared. The oxide shell around the nanocrystalline core formed during laser processing in water offers the required conditions for the confinement of excitons that allow for stable (in either air or water) blue photoluminescence at room temperature.

Ambient-stable blue luminescent silicon nanocrystals prepared by nanosecond-pulsed laser ablation in water.

A silicon nanocrystals (Si-ncs) conjugated-polymer-based bulk-heterojunction represents a promising approach for low-cost hybrid solar cells. In this contribution, the bulk-heterojunction is based on Si-ncs prepared by electrochemical etching and poly(3-hexylthiophene) (P3HT) polymer. Photoelectric properties in parallel and vertical device-like configuration were investigated. Electronic interaction between the polymer and surfactant-free Si-ncs is achieved. Temperature-dependent photoluminescence and transport properties were studied and the ratio between the photo- and dark-conductivity of 1.7 was achieved at ambient conditions. Furthermore the porous titanium dioxide (TiO(2)) nanotubes' template was used for vertical order of photosensitive Si-ncs/P3HT-based blend. The anodization of titanium foil in ethylene glycol-based electrolyte containing fluoride ions and subsequent thermal annealing were used to prepare anatase TiO(2) nanotube arrays. The arrays with nanotube inner diameter of 90 and 50 nm were used for vertical ordering of the Si-ncs/P3HT bulk-heterojunction.

Photoelectric Properties of Silicon Nanocrystals/P3HT Bulk-Heterojunction Ordered in Titanium Dioxide Nanotube Arrays.

We performed studies of the self-organization processes in nanoporous alumina membranes at initial and late stages of aluminum anodization by using scanning electron microscopy (SEM) and small-angle neutron scattering (SANS). SEM observations indicated three stages in the self-organization of nanopores in alumina: (1) nucleation of random nanopores with a broad radius distribution, (2) narrowing the radius distribution and (3) slow evolution of the nanoporous structure towards ordering of nanopores into large domains. SANS studies revealed orientational correlation between ordered domains of nanopores, which is characterized by a small misorientation angle. For the samples with high aspect ratios of nanopores, the SANS patterns showed azimuthal smearing, which was attributed to the redistribution of nanopores between the domains during their growth.

Studies of self-organization processes in nanoporous alumina membranes by small-angle neutron scattering.

Efficient photocatalytic water splitting requires effective generation, separation and transfer of photo-induced charge carriers that can hardly be achieved simultaneously in a single material. Here we show that the effectiveness of each process can be separately maximized in a nanostructured heterojunction with extremely thin absorber layer. We demonstrate this concept on WO3/BiVO4+CoPi core-shell nanostructured photoanode that achieves near theoretical water splitting efficiency. BiVO4 is characterized by a high recombination rate of photogenerated carriers that have much shorter diffusion length than the thickness required for sufficient light absorption. This issue can be resolved by the combination of BiVO4 with more conductive WO3 nanorods in a form of core-shell heterojunction, where the BiVO4 absorber layer is thinner than the carrier diffusion length while it's optical thickness is reestablished by light trapping in high aspect ratio nanostructures. Our photoanode demonstrates ultimate water splitting photocurrent of 6.72 mA cm(-2) under 1 sun illumination at 1.23 V(RHE) that corresponds to ~90% of the theoretically possible value for BiVO4. We also demonstrate a self-biased operation of the photoanode in tandem with a double-junction GaAs/InGaAsP photovoltaic cell with stable water splitting photocurrent of 6.56 mA cm(-2) that corresponds to the solar to hydrogen generation efficiency of 8.1%.

Article	Year
Synthesis of chemotactic peptide analogs with a photoaffinity cross-linker as new probes for analysis of receptor-ligand interaction. Protein and peptide letters\| PubMed ID: 12678812	2003
Effect of alpha,alpha-dialkyl amino acids on the protease resistance of peptides. Bioscience, biotechnology, and biochemistry\| PubMed ID: 14586119	2003
Ambient-stable blue luminescent silicon nanocrystals prepared by nanosecond-pulsed laser ablation in water. Optics express\| PubMed ID: 19158863	2009
Photoelectric Properties of Silicon Nanocrystals/P3HT Bulk-Heterojunction Ordered in Titanium Dioxide Nanotube Arrays. Nanoscale research letters\| PubMed ID: 20628462	2009
Studies of self-organization processes in nanoporous alumina membranes by small-angle neutron scattering. Nanotechnology\| PubMed ID: 22828486	2012
Photocatalytic generation of hydrogen by core-shell WO₃/BiVO₄ nanorods with ultimate water splitting efficiency. Scientific reports\| PubMed ID: 26053164	2015

Michio Kondo

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