超伝導酸化物の合成, 物性及び化学修飾に関する研究

本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである京都大学0048新制・課程博士博士(工学)甲第6043号工博第1440号新制||工||989(附属図書館)UT51-95-D362京都大学大学院工学研究科分子工学専攻(主査)教授 横尾 俊信, 教授 山邊 時雄, 教授 曽我 直弘学位規則第4条第1項該当Doctor of EngineeringKyoto UniversityDFA

Effective Sol-Gel Nanocoatings on ZnO Electrodes for Suppressing Recombination in Dye-Sensitized Solar Cells

Attempts have been made to improve the performance of dye-sensitized solar cells by forming metal-oxide nanocoating layers on ZnO electrodes by a sol-gel transformation. SiO2, Nb2O5, TiO2, or ZrO2 nanocoating layers could be formed by dipping ZnO films into metal alkoxide solutions of low concentrations and subsequent heat treatments. The performance of DSSCs using the coated ZnO electrodes depends strongly on the structure of coating layers such as the thickness and the surface coverage, which are significantly influenced by the coating conditions. In particular, SiO2 and Nb2O5 coating layers are effective to suppress the recombination by constructing the energy barrier at the ZnO/electrolyte interface and enhance energy conversion efficiency. It is found that the coating layers also hinder the grain growth of ZnO, contributing to the enhanced cell performance as well

Low-Temperature Deposition of Nanocrystalline ZnO Phosphor Films from Neutral Ethanolic Zinc Acetate Solutions in the Absence of Base

Nanocrystalline ZnO phosphor films were prepared from an ethanolic solution of zinc acetate dihydrate on fluorine-doped tin oxide coated glass substrates through a chemical bath deposition at a low temperature of 60°C. Because the deposition was achieved without using a base such as NaOH or LiOH, the ZnO film prepared was chemically pure in terms of cation impurities. It was indicated that the deposition of ZnO 26 Another problem encountered in these methods is that they include procedures that are harmful to certain kinds of practically useful substrate materials for film depositions. Basic solutions employed in colloid For the film deposition, a portion of the above-mentioned solution was placed into a 20 mL glass bottle with a tight-fitting screw cap. Conducting glass plates coated with F-doped SnO 2 ͑FTO͒ were used as substrates. The glass substrate was immersed in the solution so that it could slant against the bottle wall and the FTO-coated side could face the bottom of the bottle. The bottle was placed in a constant temperature oven and kept at 60°C for 48 h. After the deposition, the substrates were removed from the bottle, rinsed with ethanol, and dried at room temperature. Crystal structure identification was made by X-ray diffraction ͑XRD͒ with a Rigaku model RAD-C diffractometer using Cu K␣ radiation. Morphology and particle sizes were observed by fieldemission scanning electron microscopy ͑FESEM͒ and highresolution transmission electron microscopy ͑HRTEM͒ with a Hitachi model S-4700 and a Philips model TECNAI F20 microscope, respectively. Photoluminescence ͑PL͒ spectra were measured at room temperature with a Shimadzu model RF-5700PC using a Xe lamp ͑150 W͒ as a UV light source. Results and Discussion We first examined a reaction pathway of the ZnO formation under the neutral condition in the absence of base. It is reported that alkoxyacetate complexes are formed in polyol solutions of zinc acetate dihydrate, which leads to the formation of layered hydroxide zinc acetate ͑LHZA͒, Zn 5 (OH) 8 (CH 3 COO) 2 •2H 2 O. 27 Interestingly, we have also observed the precipitation of LHZA and its derivatives, which have slightly different compositions, in the ethanolic solution during heating at 60°C.

Fabrication of Luminescent Antireflective Coatings with CaMoO4:Eu3+/Ag Composite Structure

Highly transparent and luminescent CaMoO4:Eu3+/Ag composite films were fabricated on glass substrates as multifunctional antireflective (AR) coatings. The films were deposited through a combination of a sol–gel dip-coating technique and a hot water treatment. With the addition of an aluminum source in coating solutions, the sol–gel-derived films underwent a remarkable microstructural change during the hot water treatment due to the reaction between an amorphous alumina phase and water. This change brought both an antireflective effect (suppression of Fresnel reflection) and luminescence enhancement (suppression of total internal reflection) to the films. The introduction of Ag nanoparticles into the films further increased luminescence intensity without losing the antireflective effect

A biphasic sol–gel route to synthesize anatase TiO2 particles under controlled conditions and their DSSC application

A biphasic sol–gel method was introduced to reduce a high hydrolysis rate of metal alkoxides and control a morphological evolution of metal oxides. Titanium tetraisopropoxide (TTIP) was dissolved in an organic solvent which was immiscible with water. The TTIP solution was then contacted with water or pH-controlled aqueous solutions to promote the hydrolysis and the polycondensation reaction through the mass transfer across the organic/aqueous interface. Anatase TiO2 was formed in any conditions employed in the present work at reaction temperatures of 80 °C or below. The morphology of TiO2 particles obtained was largely dependent on the kind of organic solvents. It was basically the aggregation of nanoparticles to give submicrometer-sized secondary particles with or without a regular shape. Heptane was found to be suitable to obtain spherical TiO2 large particles, which were evaluated as a photoanode material in dye-sensitized solar cells. Actually the large TiO2 particles worked well as the light scattering layer when applying them to a double-layered phtoanode, which showed an energy conversion efficiency of 5.67% with a high short-circuit photocurrent density of 14.1 mA cm−2