Publications by authors named "Kazutaka Akiyoshi"

Luminescence color tuning of less toxic I-III-VI-based quantum dots (QDs) has been intensively investigated for application in wide-color-gamut displays. However, the emission peaks of these multinary QDs are relatively broad in the blue-light region compared to those in the green and red regions. Here, we report the synthesis of AgGaS (AGS) QDs that show a narrow blue emission peak through nonstoichiometry control and surface defect engineering.

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Photosensitization of semiconductors by excitation of chiral plasmonic metallic nanostructures has attracted much attention, not only for the analysis and detection of circularly polarized light but also for its potential applications in chiral photosynthesis. Although there have been reports on the detection of semiconductor-sensitized current in chiral nanostructures precisely fabricated by physical vapor deposition and/or lithography techniques, there have been no studies using plasmonic metal nanocolloids synthesized by chemical processes. In this study, we report the establishment of a fabrication method for large-area chiral photoelectrodes and the semiconductor photosensitization phenomenon realized using chiral plasmonic nanoparticles.

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I-III-VI-based semiconductor quantum dots (QDs) have been intensively explored because of their unique controllable optoelectronic properties. Here we report one-pot synthesis of Na-doped Ag-In-Ga-S (AIGS) QDs incorporated in a GaO matrix. The obtained QDs showed a sharp band-edge photoluminescence peak at 557 nm without a broad-defect site emission.

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Narrowing the emission peak width and adjusting the peak position play a key role in the chromaticity and color accuracy of display devices with the use of quantum dot light-emitting diodes (QD-LEDs). In this study, we developed multinary Cu-In-Ga-S (CIGS) QDs showing a narrow photoluminescence (PL) peak by controlling the Cu fraction, i.e.

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AuRh bimetallic alloy nanoparticles (NPs) were successfully prepared by simultaneous sputtering of Au and Rh in a room-temperature ionic liquid (RTIL) of ,-diethyl--methyl--(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF). Bimetallic AuRh alloy NPs of 1-2 nm in size were formed in the RTIL. The alloy composition was controllable by changing the surface areas of Au and Rh plates used as sputtering targets.

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Nanoparticles composed of molybdenum oxide, MoO , were successfully prepared by room-temperature ionic liquid (RTIL)/metal sputtering followed by heat treatment. Hydroxyl groups in RTIL molecules retarded the coalescence between MoO NPs during heat treatment at 473 K in air, while the oxidation state of Mo species in MoO nanoparticles (NPs) could be modified by changing the heat treatment time. An LSPR peak was observed at 840 nm in the near-IR region for MoO NPs of 55 nm or larger in size that were annealed in a hydroxyl-functionalized RTIL.

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We prepared a solid-state Z-scheme photocatalyst in which zinc rhodium oxide (ZnRhO) and bismuth vanadium oxide (BiVO) that served as hydrogen (H) and oxygen (O) evolution photocatalysts, respectively, were connected with gold (Au) nanoparticles. The Au nanoparticles were prepared by sputtering in an ionic liquid, N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide, to generate Au/ZnRhO/Au/BiVO with various amounts of Au in the 12 mol. %-29 mol.

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Plasmon-induced charge separation (PICS) at the interface between a plasmonic nanoparticle and a semiconductor becomes less efficient as the plasmon resonance wavelength increases, because the energy of a photon may not be sufficiently higher than the interfacial Schottky barrier height. In this study, we developed PICS photocathodes by coating Au nanoparticles of different sizes on an ITO electrode with a thin TiO2 layer, and applied negative potentials to those photocathodes so as to suppress back electron transfer and improve the PICS photocurrent responses. The photocurrent enhancement factor was increased as the particle size was decreased, and enhancement of about two orders of magnitude was observed for small Au nanoparticles when bias voltage of 0.

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Potentiometric and conductometric sensors based on localized surface plasmon resonance were developed. The sensors can be applied to coloured and turbid samples because light need not pass through the sample solution.

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