• Applied Chemistry for Engineering
• /
• v.9 no.7
• /
• pp.998-1003
• /
• 1998

$BaTiO_3$ thin film was electrochemically deposited on Ti electrode in a 0.4 M $Ba(OH)_2$ solution of $85^{\circ}C$ using a current pulse waveform. Both $BaTiO_3$ crystallinity and faradaic efficiency for the film formation were enhanced with the increase of cathodic current density and pulse time. Based on the surface analysis and electrochemical studies, it was suggested that, during cathodic pulsed, the surface pH increase due to the reduction of $H_2O$ accelerates the structural changes of Ti oxides which were formed during anodic cycle. Prior to experiments, Ti oxides were intentionally grown in 0.1 M $H_2SO_4$ solution and the effect of initial oxide film thickness on the $BaTiO_3$ film formation was investigated. The migration of $Ti^{+4}$ ions through the oxide film was retarded with the increase of film thickness and it was observed that the crystallization of $BaTiO_3$ was only limited to the defect area of surface oxides.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.2
• /
• pp.109-117
• /
• 2018

A novel carbon paste electrode modified with $Cu-TiO_2$ nanocomposite, 2-(ferrocenylethynyl)fluoren-9-one (2FF) and ionic liquid (IL) (2FF/$Cu-TiO_2$/IL/CPE) was fabricated and employed to study the electrocatalytic oxidation of droxidopa, using cyclic voltammetry (CV), chronoamperometry (CHA) and differential pulse voltammetry (DPV) as diagnostic techniques. It has been found that the oxidation of droxidopa at the surface of modified electrode occurs at a potential of about 295 mV less positive than that of an unmodified CPE. DPV exhibits a linear dynamic range from $5.0{\times}10^{-8}$ to $4.0{\times}10^{-4}M$ and a detection limit of 30.0 nM for droxidopa. Finally this modified electrode was used for simultaneous determination of droxidopa and tryptophan. Also the 2FF/$Cu-TiO_2$/IL/CPE shows excellent ability to determination of droxidopa and tryptophan in real samples.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1996.11a
• /
• pp.50-50
• /
• 1996

• Bulletin of the Korean Chemical Society
• /
• v.34 no.3
• /
• pp.856-862
• /
• 2013

The photoanode electrode of $TiO_2$ nanotubes (NTs) anchored with ZnS/CdSSe/CdS quantum dots (QDs) was prepared by anodization of Ti metal and successive ionic layer adsorption and reaction (SILAR) procedure. The tuning of the band gap of CdSSe was done with controlled composition of Cd, S, or Se during the SILAR. A ladder-like energy structure suitable for carrier transfer was attained with the photoanode electrode. The power conversion efficiency (PCE) of our solar cell fabricated with the regular array of $TiO_2$ NTs anchored with CdSSe/CdS or CdSe/CdS QDs [i.e., (CdSSe/CdS/$TiO_2NTs$) or (CdSe/CdS/$TiO_2NTs$)] was PCE = 3.49% and 2.81% under the illumination at 100 mW/$cm^2$, respectively. To protect the photocorrosion of our solar cell from the electrolyte and to suppress carrier recombination, ZnS was introduced onto CdSSe/CdS. The PCE of our solar cell with the structure of a photoanode electrode, (ZnS/CdSSe/CdS/$TiO_2$ NTs/Ti) was 4.67% under illumination at 100 mW/$cm^2$.

• Proceedings of the KIEE Conference
• /
• 2004.11a
• /
• pp.75-78
• /
• 2004

$Bi_{3.25}Eu_{0.75}Ti_3O_{12}$ (BET) thin films were deposited on the $LaNiO_3$ (LNO (100))/Si and Pt/Ti/$SiO_2$/Si substrates by the metal-organic decomposition method. Structural and dielectric properties of BLT thin films for the applications in nonvolatile ferroelectric random access memories were investigated. Both the structure and morphology of the films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). Even at low temperatures $650^{\circ}C$, the BET thinfilms were successfully deposited on LNO bottom electrode and exhibited (001) and (117) orientation. Compared with the Pt electrode films, the BET thin films on the LNO electrode annealed at $650^{\circ}C$ showed better dielectric constantsand remanent polarization. The BET thin films on the LNO electrode for the annealing temperature of $650^{\circ}C$, the remanent polarization Pr and coercive field were $45.6\;C/cm^2$ and 171 kV/cm, respectively.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.53.2-53.2
• /
• 2011

Dye-sensitized solar cells(DSSCs) have been recognized as an alternative to the conventional p-n junction solar cells because of their simple fabrication process, low production cost, and transparency. A typical DSSC consists of a transparent conductive oxide (TCO) electrode, a dye-sensitized oxide semiconductor nanoparticle layer, liquid redox electrolyte, and a Pt-counter electrode. In dye-sensitized solar cells, charge recombination processes at interfaces between coducting glass, $TiO_2$, dye, and electrolyte play an important role in limiting the photon-to-electron conversion efficiency. A layer of ZTO thin film less than ~200nm in thickness, as a blocking layer, was deposited by DC magnetron sputtering method directly onto the anode electrode to be isolated from the electrolyte in dye-sensitized solar cells(DSCs). This is to prevent the electrons from back-transferring from the electrode to the electrolyte ($I^-/I_3^-$). The presented DSCs were fabricated with working electrode of Ga-doped ZnO glass coated with blocking ZTO layer, dye-attached nanoporous $TiO_2$ layer, gel electrolyte and counter electrode of Pt-deposited GZO glass. The effects of blocking layer were studied with respect to impedance and conversion efficiency of the cells.

• Korean Journal of Materials Research
• /
• v.1 no.4
• /
• pp.229-235
• /
• 1991

A new electrode material for $Ta_2O_5$ capacitor was developed to obtain both high dielectric constant and improved electrical properties for use in DRAM. High leakage current and low breakdown field of as-deposited $Ta_2O_5$ film on Si is due to the reduction of $Ta_2O_5$ by silicon at $Ta_2O_5$/electrode interface. $Dry-O_2$ anneal improves the electrical properties of $Ta_2O_5$ capacitor with Si electrode, but it thickens the interfacial oxide and lowers the dielectric constant, subsequently. $Ta_2O_5$ capacitor with TiN exectrode shows better electrical properties and higher dielectric constant than post heat treated $Ta_2O_5$ film on Si. No interfacial oxide layer at $Ta_2O_5$/TiN interface suggests that there\`s no Interaction between $Ta_2O_5$ and electrode. TiN is a adequate electrode material for $Ta_2O_5$ capacitor.

• Korean Chemical Engineering Research
• /
• v.48 no.4
• /
• pp.506-510
• /
• 2010

Electron recombinations in electrolyte solution reduce light-to-energy conversion efficiency at the nanoporous electrode surface of dye sensitized solar cells. In this study, we improved the conversion efficiency using an energy barrier at the nanoporous electrode surface to control the recombination process. The energy barrier was formed by coating nanoporous $TiO_2$ electrode with $Nb_2O_5$ material. We investigated the influence of energy barrier on the cell efficiency depending on the coating thickness. Nanoporous $TiO_2$ electrode was coated about 5 nm thickness by 12 times coatings, and so the coating layer was grown about 0.417 nm for every time. Enhancement of conversion efficiency from 2.55% to 4.25% was achieved at 0.834 nm coating thickness, and it was believed as the optimum thickness for minimizing the electron recombination process in our experimental system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.2
• /
• pp.115-120
• /
• 2014

Photo electrode is an important component for DSSC. DSSCs electrical characteristics and efficiencies fabricated with different $TiO_2$ photo electrodes thickness and modified phoro electrode surface area were studied. $11{\mu}m$ $TiO_2$ photo electrode shows a 4.956% efficiency. The highest short circuit current density was a $9.949mA/cm^2$. Efficiencies and short circuit current density increased as tape casting thickness decreased. Modified surface area of the photo electrode by needle stamp processing were studied. 200 times needle stamp processing on photo electrodes shows a highest 5.168% efficiency. Also the short circuit current density was a $10.261mA/cm^2$.

• Journal of Electrical Engineering and Technology
• /
• v.5 no.1
• /
• pp.146-150
• /
• 2010

A new type of dye-sensitized solar cell (DSC) based on a porous type Ti electrode without using a transparent conductive oxide (TCO) layer is fabricated for low-cost high-efficient solar cell application. The TCO-free DSC is composed of a glass substrate/dye-sensitized $TiO_2$ nanoparticle/porous Ti layer/electrolyte/Pt sputtered counter electrode. The porous Ti electrode (~350 nm thickness) with high conductivity can collect electrons from the $TiO_2$ layer and allows the ionic diffusion of $I^-/I_3{^-}$ through the hole. The vacuum annealing treatment is important with respect to the interfacial necking between the metal Ti and porous $TiO_2$ layer. The efficiency of the prepared TCO-free DSC sample is about 3.5% (ff: 0.48, $V_{oc}$: 0.64V, $J_{sc}$: 11.14 mA/$cm^2$).