Na-Yeong Hong

Effect of Acetic Acid in TiCl4 Post-Treatment on Nanoporous TiO2 Electrode in Dye-Sensitized Solar Cell

Titanium tetrachloride (TiCl4) is adopted as a post-treatment on the nanoporous titanium oxide (TiO2) layers to enhance the performance of dye-sensitized solar cells (DSCs). A TiCl4 post-treatment is capable of improving electron transport and dye-loading on the surface of TiO2 layers. In this study, the TiCl4 solution mixed with acetic acid was employed to enhance the condition of the TiCl4 post-treatment. Since acetic acid in the TiCl4 solution prevents the formation of impurities and facilitates the crystallization, it improves dye adsorption and electron transport properties. To analyze the performance of the cell, we measured X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface measurements, UV–vis spectroscopy and electrochemical impedance spectroscopy (EIS) and photocurrent–voltage (I–V) measurements.

Analysis on the Light-Scattering Effect in Dye-Sensitized Solar Cell according to the TiO2 Structural Differences

A light-scattering layer is widely used in highly efficient dye-sensitized solar cells (DSCs) because it improves the light-harvesting ability of a DSC by reflecting the light passing through the transparent TiO2 layer. Among many parameters affecting this light-scattering effect, the thickness of the TiO2 photoelectrode is also a significant parameter. However, most studies regarding the influence of the TiO2 photoelectrode thickness on the light-scattering effect have only focused on the thickness of the transparent TiO2 layer and have ignored the light-scattering layer thickness itself. Therefore, in this study, we analyzed the light scattering effect according to the thickness of the light-scattering layer and the resulting photovoltaic performance of the DSC. Finally, it was confirmed that the light-scattering effect is enhanced to some degree with the increase of the light-scattering layer thickness, while it is weakened when the light-scattering layer thickness is further increased.

A Study on FTO-less Dye Sensitized Solar Cell with Ti Deposited Glass

Dye-sensitized solar cells (DSCs) have taken much attention due to their low cost and easy fabrication method compare to silicon solar cells. But research on cost effective DSC is prerequisite for commercialization. Fluorine doped tin oxide (FTO) which have been commonly used for electrode substrate as electron collector occupied most percentage of manufacturing cost. Therefore we studied FTO-less DSC using sputtered Ti deposited glass as photoelectrode instead of FTO to reduce manufacturing cost. Ti films sputtered on the glass for different time, 5 to 20 minutes with decreasing sheet resistance as deposition time increases. A light source illuminated to counter electrode in order to overcome opaque Ti films. The efficiency of DSC (Ti20) made Ti sputtered glass for 20 min as photoelectrode was 5.87%. There are no significant difference with conventional cell despite lower manufacturing cost.

The Enhancement of the Performance of Dye Sensitized Solar Cells Using Nb 2 O 5 -TiO 2 Compound

Niobium oxide () has a strong chemical coherence and good electrical conductivity. Therefore, this material is helpful to enhance the performance of the dye sensitized solar cells (DSC) by improving the electron mobility. In this study, was mixed with and this compound was applied to the DSC to improve its performance. As a result, the current density of the DSC using the compound on the photoelectrode was increased, because the internal resistance concerned to the electron transfer in the photoelectrode of DSC was decreased. However, large amount of the induces the decrease of the efficiency of the DSC because the surface area to attach dye molecules is decreased due to the large particle of . Therefore, it is important to optimize the mixture ratio of the compound for maximizing the performance of the DSC. Finally, the most optimum performance of the DSC was shown in case of the concentration of 10 wt% of the compound.

Growth of ZnO Nanorod with High-quality Assisted by an External Electric Field

In this study, the ZnO nanorod is grown on the seed layered glass substrate by applying an external electric field to fabricate the ZnO nanorod with the high quality and to increase the yield of the ZnO nanorod. It is possible to grow the definite and clear hexagonal ZnO nanorod as the cathode of the high voltage is connected to the side of the seed layered glass substrate and the anode is connected to the opposite side because more ions are located around the ZnO seed layer and are accumulated easily due to the external electric field. As a result, it is succeeded to fabricate the definite hexagonal ZnO nanorod having better structural characteristics by applying the external electric field during the growth process. Therefore, it is demonstrated that the external electric field is effective to fabricate the high quality ZnO nanorod without changing any composition of the ZnO nanorod.

Analyses of the Output Characteristics and the Internal Impedance of Dye-sensitized Solar Cell According to the Fabrication of the Blocking Layer

Abstract - DSCs are based on a dye-adsorbed porous TiO 2 layer as a photo electrode [1]. Under the illumination, dye molecules are excited and electrons are produced. The injected electrons in the conduction band of TiO 2 may recombine with the electrolyte. To obtain high performance DSCs, it is essential to retard the recombination. The charge recombination can be reduced by forming core-shell structure. In this work, we investigated the core-shell structure with Al 2 O 3 and MgO coating layer on the porous TiO 2 layer. We confirmed the photovoltaic properties by I-V characteristics. The current and the efficiency was improved. In addition to, Through decrease in the width of EIS arc, which is the sum of the interfacial charge transfer resistances of both electrodes, we can be indicated that the block effect.Key Words : Dye sensitized solar cell, Core-shell structure, Recombination.*정 회 원 : 부산대 공대 전자전기공학과 박사과정** 준 회 원 : 부산대 공대 전자전기공학과 석사과정***비 회 원 : 부산대 공대 전자전기공학과 조교수† 교신저자, 시니어회원 : 부산대 전자전기공학과 교수E-mail : 2heeje@pusan.ac.kr 접수일자 : 2011년 9월 23일 최종완료 : 2011년 12월 5일