Keio University · Materials Science
Yoshiki Iso 교수의 연구실은 주로 반도체 나노결정체와 나노 phosphor를 활용한 광전자 소재 개발에 중점을 두고 있습니다. 특히 페르로브스카이트 나노결정체, 이트륨 바나듐산화물 도핑 나노 phosphor, 인화물계 양자점 등 다양한 발광 물질의 합성 및 안정성 향상 기술을 연구하며, 태양전지의 효율을 높이는 스펙트럼 변환 소재와 유기-무기 복합 나노복합막의 제작에도 기여하고 있습니다. 이들의 연구는 에너지 효율 향상과 고성능 디스플레이, 태양전지 응용을 목표로 하고 있습니다.
Figures are computed from collected data and may differ slightly.
All-inorganic cesium lead halide perovskite CsPbX3 (X = Cl, Br, I) nanocrystals have emerged as promising luminescent quantum dots. In this review, we summarize recent work on their synthesis, luminescent properties, and stabilities. Through controlling the composition of the alloyed halides and quantum size effects, the band gaps and emission wavelengths of CsPbX3 nanocrystals are readily tunable over the entire visible range. Their sharp emission line-widths extend the color gamut of liquid cr
YVO4:Bi3+,Eu3+ nanophosphor converts near ultraviolet light to red light and shows lower scattering loss for visible light and long-term photostability. Therefore, the authors produce urethane resin films containing YVO4:Bi3+,Eu3+ nanophosphors on soda-lime glass substrates as spectral shifters to understand the effects of doping of Bi3+ and Eu3+ into YVO4 and the Bi3+ concentration on photoelectric conversion efficiencies of a monocrystalline silicon photovoltaic module. Under ultraviolet and n
CuGaS 2 /ZnS quantum dots were investigated for a luminescent downshifting layer and luminescent solar concentrator with a single-crystalline silicon solar module.
We fabricated nanocomposite films from an aqueous suspension of red-emitting YVO4:Bi(3+),Eu(3+) nanoparticles (hydrodynamic size: 22 ± 6 nm) and silicone-modified acrylic resin nanoparticles of (60 ± 15 nm) by electrophoretic deposition under application of a constant voltage. The nanocomposite films were formed from these negatively charged nanoparticles on ITO-coated glass substrates on the anodic side at the volume ratio of nanophosphor:resin ∼ 40:60. According to transmission electron micros
CsPbX<sub>3</sub> (X = Cl, Br, I) perovskite nanocrystals (NCs) have attracted much attention as promising materials for next-generation optoelectronic applications. However, improvement of their low stabilities against heating and humidity is needed for practical use. In this work, we focused on perfluorodecanoic acid (PFDA) as a surface ligand and investigated the thermal and chemical stabilities of the photoluminescence (PL) properties of CsPbBr<sub>3</sub> NCs. Oleic acid (OA) adsorbed on th
In this work, green-emitting InP/ZnS quantum dots (QDs) modified with 1-dodecanethiol were embedded into silica by two methods to improve their photostability while maintaining a high photoluminescence quantum yield (PLQY) and a color coordinate. A monolithic QD-silica composite prepared by a non-aqueous route with tetraethyl orthosilicate and lactic acid featured low transparency, a loss of the color purity of green, and a PLQY of 1.6%, which was considerably lower than that of the original QDs
We investigated the effects of annealing on the photoluminescence (PL) properties of a citrate-capped YVO4:Bi3+,Eu3+ nanophosphor. The 300 °C annealed nanophosphor exhibited the highest PL intensity at 619.5 nm corresponding to an f–f transition of Eu3+ under near-UV excitation. Fourier transform infrared spectroscopy indicated a decrease in the amounts of adsorbed water and citrate on the nanophosphor surface with annealing. Dehydration and the increase in near-UV absorption contributed to the
Compositions of green-emitting Y<sub>1−x−y</sub>Ce<italic>x</italic>Tb<italic>y</italic>BO<sub>3</sub> and red-emitting Y<sub>1−x−y−z</sub>Ce<italic>x</italic>Tb<italic>y</italic>Eu<italic>z</italic>BO<sub>3</sub> were optimized by photoluminescence intensity of each microplate-well by using a microplate reader.
Self-readsorption of surface ligands completely restores the photoluminescence of CsPbBr<sub>3</sub> quantum dots damaged by excitation light.
Morphologies, photoluminescence properties, and photostability were characterized for Y<sub>2</sub>O<sub>3</sub>:Bi<sup>3+</sup>,Eu<sup>3+</sup> fluorescent nanosheets prepared through calcining solvothermally synthesized layered yttrium hydroxide precursors.
Photodegraded CsPbBr3 perovskite nanocrystals (NCs) can exhibit complete self-recovery following storage in the dark. This behavior results from the readsorption of surface ligands that experienced photoinduced desorption under UV light excitation. In the present work, mixed-halide CsPb(Cl0.4Br0.6)3, CsPb(Cl0.2Br0.8)3, and CsPb(Br0.7I0.3)3 NCs were prepared via ion exchange to evaluate the influence of halide composition on the photodegradation and self-recovery of NCs. Partially substituting Cl
Fluorescent Cd-free quantum dots (QDs) such as InP/ZnS and CuInS2/ZnS have attracted attention for use as color converters for blue light emitting diodes. To protect QDs from oxygen, which degrades them by photo-oxidation during excitation, we fabricated a transparent monolithic silica composite containing the QDs using an aqueous solution of tetramethylammonium silicate (TMAS) as a silica source. The TMAS solution readily dispersed the negatively charged QDs prepared by ligand exchange of 1-dod
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