Tetsuhiko Isobe

Fluorescent carbon dots (CDs) are of interest as a promising alternative to quantum dots, partly because they do not include heavy metals. However, most CDs exhibit blue or green emission, while red-emitting CDs are required for a variety of applications. In the present work, CDs were synthesized by refluxing three phenylenediamine (PD) isomers with amino groups at different positions (<i>o</i>-PD, <i>m</i>-PD, and <i>p</i>-PD) in diphenyl ether at 250 °C for 4 h. Upon dispersing the resulting C

Calcium phosphate synthesized by a wet-mechanochemical reaction between Ca(OH)2 and H3PO4 is identified by X-ray diffractometry as an apparently single phase of hydroxyapatite (HAp). We examined more detail on the local structure of the product by high-resolution 1H and 31P solid-state double nuclear magnetic resonance (NMR) spectroscopy. Adsorbed and structural waters, as well as two kinds of OH groups in HAp, were observed in the inversion recovery 1H magic angle spinning (MAS) spectra. HAp an

Surface modification of <italic>p</italic>-phenylenediamine-derived carbon dots with decanoic acid and perfluorodecanoic acid successfully modulated fluorescence solvatochromism.

CuInS2 (CIS) quantum dots (QDs) were investigated as a luminescent downshifting (LDS) material that converts near-ultraviolet (UV) light to visible light and were applied to a single crystalline silicon (c-Si) solar module that has no spectral sensitivity in the near-UV region. The bandgap of the CIS/ZnS core/shell QDs was successfully adjusted to ∼3 eV, which was adequate for the LDS layer in solar devices, by changing the molar ratio of Cu/In. CIS/ZnS/ZnS core/shell/shell QDs with 59.9% absolu

Fluorescent carbon dots (CDs) represent a promising eco-friendly next-generation phosphor. However, most CDs exhibit broad photoluminescence (PL) spectra [full width at half-maximum (fwhm) over 60 nm]; few works on CDs with sharp PL spectra (fwhm less than 40 nm) have been reported. In addition, their syntheses and color tuning require harsh conditions of high temperatures, long reaction times, and high pressures with catalysts. Here, we successfully prepared narrow-bandwidth emissive CDs (fwhm

Surface modification of p-phenylenediamine-derived carbon dots using 4-morpholinoaniline with an electron-donating and rigid structure followed by purification using silica gel column chromatography increased the photoluminescence quantum yield from 28.3 to 41.8% in chloroform. The improved photoluminescence quantum yield was observed for the surface modification by postaddition of the surface modifier after the formation of the π-conjugated structure of the carbon dot core but was not observed

Photostable silica composites containing CuInS₂/ZnS/ZnS quantum dots were fabricated using a sol–gel method. Their photoluminescence quantum yields were 43–47%.