Sung-Jei Hong

Improvement of particle size of indium tin oxide nanoparticles by in-situ dispersion method for solution based transparent heater

In this study, particles size of indium tin oxide nanoparticles (ITO-NPs) was improved by in-situ dispersion method. Polyvinylpyrrolidone (PVP) was used as dispersing agent, and reduced precipitates heat-treated at 400 °C. Brunauer, Emmett & Teller (BET) specific surface area (SSA) analysis and X-ray diffractometer (XRD) observations found that their particle size was improved by using the in-situ dispersion. In addition, we found that the particle size of the crystalline ITO-NPs was changed with the concentration of the PVP as well as the heat-treatment temperature. When 2 wt% PVP was applied, the highest BET SSA of the ITO-NPs, 114.7 m2/g, was obtained after heat-treatment at 400 °C. In fact, the lowest sized, less than 7 nm, ITO-NPs was observed with high resolution transmission electron microscope (HRTEM). The ITO-NPs were well dispersed in the solvent to formulate a 20 wt% ITO-NPs solution. ITO-NPs coated layer on 3 × 3 cm2 quartz substrate showed sheet resistance of 319 Ω/□ and optical transmittance of 89.5% after heat-treatment at 900 °C. Heat was well generated at the ITO-NPs coated layer with supplied voltage. Also, temperature of above 150 °C was obtained from the transparent heater, and 89 °C was obtained with low power, 0.21 W/cm2, that is superior to commercial heaters.

Physical and Electrical Properties of SiO2 Layer Synthesized by Eco-Friendly Method

SiO2 thin film has a wide range of applications, including insulation layers in microelectronic devices, such as semiconductors and flat panel displays, due to its advantageous characteristics. Herein, we developed a new eco-friendly method for manufacturing SiO2 nanoparticles and, thereby, SiO2 paste to be used in the digital printing process for the fabrication of SiO2 film. By excluding harmful Cl- and NO3- elements from the SiO2 nanoparticle synthetic process, we were able to lower the heat treatment temperature for the SiO2 precursor from 600 to 300 °C and the diameter of the final SiO2 nanoparticles to about 14 nm. The synthesized SiO2 nanoparticles were dispersed in an organic solvent with additives to make a SiO2 paste for feasibility testing. The SiO2 paste was printed onto a glass substrate to test the feasibility of using it for digital printing. The insulation resistance of the printed film was high enough for it to be used as an insulation layer for passivation.

ITO nanoparticles reused from ITO scraps and their applications to sputtering target for transparent conductive electrode layer

In this study, ITO nanoparticles (ITO-NPs) were reused from ITO target scraps to synthesize low cost ITO-NPs and to apply to make sputtering target for transparent conductive electrodes (TCEs). By controlling heat-treatment temperature as 980xa0°C, we achieved reused ITO-NPs having Brunauer, Emmett and Teller specific surface area (BET SSA) and average particle size 8.05xa0m2/g and 103.8xa0nm, respectively. The BET SSA decreases along with increasing heat-treatment temperature. The ITO-NPs were grown as round mound shape, and highly crystallized to (222) preferred orientations. Also, applying the reused ITO-NPs, we achieved an ITO target of which density was 99.6%. Using the ITO target, we achieved high quality TCE layer of which sheet resistance and optical transmittance at 550xa0nm were 29.5xa0Ω/sq. and 82.3%. Thus, it was confirmed that the reused ITO-NPs was feasible to sputtering target for TCEs layer.