Papers by Author: Hong Lin

Abstract: Research on the flexible dye-sensitized solar cells (DSCs) has been more and more extensively conducted during the recent years both academically and comercially for the sake of its further reduced expense and even broader application. However, significant promotion of electron transport properties and consequently the photovoltaic performances of such devices are perpetually hindered by the key problem that the poor heat tolerance of the plastic substrates employed in flexible DSCs makes high-temperature sintering of the photoanode films impossible. Based on a brief overview of the current state of research on flexible DSCs, including new materials and delicate processing techniques, and the research results from the author’s own group, this chapter specially treats the profound mechanistic issue of electron transport and recombination in flexible DSCs, which is rarely discussed and relatively less well understood up to now. It is pointed out that the electron transport and recombination dominate photovoltaic performance of the flexible DSCs and suppressing the recombination of injected electrons with electrolyte redox species is of crucial sense for performance promotion. Besides, the methods for restraining electron recombination are proposed and the developing trend and prospects of flexible DSCs are also presented.

Abstract: The present paper summarizes the technology and basic process for fabricating transparent ceramic MgAl2O4 spinel and introduces a scalable production technique. Fully transparent polycrystalline spinel has been prepared by combined vacuum sintering, hot-pressing, sintering in H2 atmosphere and hot isostatic pressing(HIP). The optical transmittance of the specimen sintered at 1500°C following HIP at 1800°C was nearly the same as that of single crystal spinel. When radiated by γ-ray and X- ray, colorless spinel became brown due to V-type color centers, which decreased its transmittance. On the other hand, the spinel ceramics’ resistance to radiation improved by doping CeO2.

Abstract: Screen printing has been considered to be the simplest and quickest way to fabricate dye- sensitized solar cells (DSCs) modules for an assembly line. 20cm×10cm DSCs modules with W-type series connection and parallel connection were fabricated. The whole fabricating process was all operated by screen-printing except for the injection of electrolyte. The optimized TiO2 electrode thickness, sealant thickness and platinum counter electrode thickness were investigated. The modules showed a reliable performance.

Abstract: The effects of rare earth oxides (Lu2O3 and La2O3) on the property, microstructure and oxidation behavior of hot-pressing sintered Si3N4 ceramics were investigated. The silicon nitride ceramics with Lu2O3 and La2O3 as addition have been fabricated by hot-pressed at 1800°C for 1h under a pressure of 25MPa. Oxidation test was carried out at 1400°C in air for 100 hours. Mechanical properties, SEM and XRD were measured before and after oxidation. The results showed that Si3N4 ceramics doped Lu2O3 had good microstructure and mechanical properties than those doped La2O3. Oxidation test showed a parabolic weight gain with oxidation time at 1400°C in air and the oxidation products of the ceramics were SiO2, Re2Si2O7 and Re2SiO5 confirmed by XRD and EDS. The rate-controlling step was the diffusion of ion. The samples doped Lu2O3 showed superior oxidation resistance to those doped La2O3.

Abstract: TiO2 nanocrystalline films were prepared by electrophoretic deposition (EPD) under a pulseperiodic electric field. The EPD behavior of TiO2 nanocrystalline suspension was investigated. The uniform 9.2-μm-thick TiO2 film was obtained by reasonably controlling the EPD condition. A dye-sensitized solar cell, with the EPD TiO2 film as the photoanode, obtained about 4.1% of photon-to-electron conversion efficiency (η). Its Jsc, Voc and fill factor (ff) are 11.6 mA/cm2, 0.65 V and 0.55, respectively. The effect of TiCl4 modification on the photovoltaic property of the solar cell was also discussed.

Abstract: In this article, the spinel NiCo2O4 nanosheets with diameters of 100-200 nm were prepared by calcinations of co-precipitates, which were obtained by co-precipitation method. Different kinds of precipitants, including NaOH, KOH, Na2CO3 and ethanedioic acid aqueous solutions were investigated, and regular hexagonal nanosheets are synthesized only when the precipitant is strong KOH or NaOH solution. The morphology and structure of the hexagonal precursor particles and nanosheets were investigated, and the mechanism of the formation of hexagonal nanosheets is discussed.

Abstract: In this paper, firstly, titanate nanotubes was synthesized by hydrothermal method with commercial antase-type TiO2 powder as the raw material. TiO2 nanotubes (TNTs) can be obtained by heat-treating the as-prepared titanate nanotubes at 400 °C. Secondly, an electrode with 30 % TNTs and 70% nanocrystalline TiO2 was designed and prepared successfully. By using the nano-electrode as the photoanode of DSC, the light-to-energy conversion efficiency of 5.42 % was obtained. In addition, the effect of hydrothermal temperature on the crystal growth of nanotubes and the effect of tert-butyl pyridine (TBP) on the photoelectric performance of the DSC were also discussed.

Abstract: Silicon nitride ceramics were fabricated with Yb2O3 as the sintering additive. The effects of the amount of Yb2O3 on the microstructure and the mechanical properties such as the flexural strength and the fracture toughness were investigated. Almost fully densified Si3N4 was obtained when only 4 wt% Yb2O3 was added. Both the flexural strength and the fracture toughness increased steadily with the Yb2O3 content. The transgranular fracture mode was observed in the specimen containing 4 wt% Yb2O3, however, the intergranular fracture mode was observed in the specimen containing 10 wt% Yb2O3.

Abstract: Wollastonite powder was selected as a starting material with carbonate as pore-forming agent and binder added. The porous ceramics were prepared at different temperature by sintering method. The process includes batching, granulating, pressing molding, drying and sintering. It is discussed the influence of sintering temperature, dosage of binder, dosage of pore-forming agent, pressure of molding and holding time on the performance of porous ceramics. According to the principle of particles stack, the porous wollastonite ceramics for filtration with various diameters, shapes and porosity were fabricated by serial experiments. These products have 1 to 10 microns in pore size, 30.04 to 66.15% in porosity, 2.82 m2/g in specific surface area.