• Korean Journal of Materials Research
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• v.32 no.1
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• pp.51-55
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• 2022

Generally, Au electrodes are the preferred top metal electrodes in most perovskite solar cells (PSCs) because of their appropriate work function for hole transportation and their resistance to metal-halide formation. However, for the commercialization of PSCs, the development of alternative metal electrodes for Au is essential to decrease their fabrication cost. Ag electrodes are considered one of the most suitable alternatives for Au electrodes because they are relatively cheaper and can provide the necessary stability for oxidation. However, Ag electrodes require an aging-induced recovery process and react with halides from perovskite layers. Herein, we propose a bilayer Au/Ag electrode to overcome the limitations of single Au and Ag metal electrodes. The performance of PSCs based on bilayer electrodes is comparable to that of PSCs with Au electrodes. Furthermore, by using the bilayer electrode, we can eliminate the aging process, normally an essential process for Ag electrodes. This study not only demonstrates an effective method to substitute for expensive Au electrodes but also provides a possibility to overcome the limitations of Ag electrodes.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.206-213
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• 2019

The development of simple methods for As detection has received great attention because As is a toxic chemical element causing environmental and health-related issues. In this work, the effect of nanostructures of Au electrodes on their electroanalytical performance during As detection was investigated. Different Au nanostructures with various surface morphologies such as nanoplate Au, nanospike Au, and dendritic Au structures were prepared, and their electrochemical behaviors toward square-wave anodic stripping voltammetric As detection were examined. The difference in intrinsic efficiency for As detection between nanostructured and flat Au electrodes was explained based on the crystallographic orientations of Au surfaces, as examined by the underpotential deposition of Pb. The most efficient As detection performance was obtained with nanoplate Au electrodes, and the effects of the pre-deposition time and interference on As detection of the nanoplate Au electrodes were also investigated.

• Journal of the Korean Chemical Society
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• v.58 no.6
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• pp.513-516
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• 2014

We measure the conductance of a 4,4'-diaminobiphenyl formed with Ni electrodes using a scanning tunneling microscope-based break-junction technique. For comparison, we use Au or Ag electrodes to form a metal-molecular junction. For molecules that conduct through the highest occupied molecular orbital, junctions formed with Ni show similar conductance as Au and are more conductive than those formed with Ag, consistent with the higher work function for Ni or Au. Furthermore, we observe that the measured molecular junction length that is formed with the Ni or Au electrodes was shorter than that formed with the Ag electrodes. These observations are attributed to a larger gap distance of the Ni or Au electrodes compared to that of the Ag electrodes after the metal contact ruptures. Since our work allows us to measure the conductance of a molecule formed with various electrodes, it should be relevant to molecular electronics with versatile materials.

• Journal of the Korean Chemical Society
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• v.60 no.5
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• pp.310-316
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• 2016

Oxidation-reduction cycling (ORC) procedures are widely used for cleaning nanoparticle surfaces when investigating their electrocatalytic activities. In this work, the effect of ORC on the surface structures and electrocatalytic oxygen reduction activity of Au electrodes is analyzed. Different structural changes and variations in electrocatalysis are observed depending on the initial structure of the Au electrodes, such as flat bulk, nanoporous, nanoplate, or dendritic Au. In particular, dendritic Au structures lost their sharp-edge morphology during the ORC process, resulting in a significant decrease in its electrocatalytic oxygen reduction activity. The results shown in this paper provide an insight into the pretreatment of nanoparticle-based electrodes during investigation of their electrocatalytic activities.

• Journal of the Korean Chemical Society
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• v.59 no.1
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• pp.18-21
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• 2015

We use a scanning tunneling microscope based break-junction technique to measure the conductance of a 4,4'-dimethoxybiphenyl molecular junction formed with Ag and Au electrodes. We observe the formation of a clear molecular junction with Ag electrodes that result from stable Ag-oxygen bonding structures. However we have no molecular bonding formation when using Au electrodes, resulting in a tunneling current between the top and bottom metal electrodes. We also see a clear peak in the conductance histogram of the Ag-oxygen molecular junctions, but no significant molecular features are seen with Au electrodes. Our work should open a new path to the conductance measurements of single-molecule junctions with oxygen linkers.

• Transactions on Electrical and Electronic Materials
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• v.9 no.4
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• pp.151-155
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• 2008

Using pentacene field effect transistors (FETs) with Au source and drain electrodes, electron injection from the Au electrodes into the pentacene was investigated. The capacitance-voltage (C-V) and optical second harmonic generation (SHG) measurements were employed. Electron injection from the Au electrodes was suggested by the hysteresis behavior with the C-V characteristics and slowly decaying SHG signal under DC biasing, A mechanism of hole-injection assisted by trapped electrons is proposed. To confirm electron injection process, light-emitting behavior under the application of AC applied voltage was observed.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.131-131
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• 2010

We compared the electrical, optical, structural, and interface properties of indium zinc oxide (IZO)-Ag-IZO and IZO-Au-IZO multilayer electrodes deposited by linear facing target sputtering system at room temperature for organic photovoltaics. The IZO-Ag-IZO and IZO-Au-IZO multilayer electrodes show a significant reduction in their sheet resistance (4.15 and 5.49 Ohm/square) and resistivity ($3.9{\times}10^{-5}$ and $5.5{\times}10^{-5}$Ohm-cm) with increasing thickness of the Ag and Au layers, respectively. In spite of its similar electrical properties, the optical transmittance of the IZO-Ag-IZO electrode is much higher than that of the IZO-Au-IZO electrode, due to the more effective antireflection effect of Ag than Au in the visible region. In addition, the Auger electron spectroscopy depth profile results for the IZO/Ag/IZO and IZO/Au/IZO multilayer electrodes showed no interfacial reaction between the IZO layer and Ag or Au layer, due to the low preparation temperature. To investigate in detail the Ag and Au structures on the bottom IZO electrode with increasing thickness, a synchrotron x-ray scattering examination was employed. Moreover, the OSC fabricated on the IZO-Ag-IZO electrode shows a higher power conversion efficiency (3.05%) than the OSC prepared on the IZO-Au-IZO electrode (2.66%), due to its high optical transmittance in the wavelength range of 400-600 nm, which is the absorption wavelength of the P3HT:PCBM active layer.

• Journal of the Korean Chemical Society
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• v.59 no.2
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• pp.132-135
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• 2015

Bonding force and stiffness in amine-linked single-molecule junctions for Ag electrodes were measured using a home-built conducting atomic force microscope under ambient conditions at room temperature. For comparison, Au electrodes were used to measure the rupture force and stiffness of the molecular junctions. The traces of the force along with the conductance showed a characteristic saw-tooth pattern owing to the breaking of the metal atomic contacts or the metal-molecule- metal junctions. We found the rupture force and stiffness for Ag are smaller than those for Au electrodes. Furthermore, we observed that the force required to break the amine-Ag bond in the conjugated molecule, 1,4-benzenediamine, is smaller than in 1,4-butanediamine which is fully saturated. These results consist with the previous theoretical calculations for the binding energies of the nitrogen bonded to Ag or Au atoms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5586-5590
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• 2015

In this paper, the directed alignment methode of the DNA molecule between the Au electrodes was suggested for the application of nano devices. To fabricate the nano device coated DNA, 2-Aminoethanthiol(AET) was coated on Au electrodes which was formed using photo-lithography process on $SiO_2/Si$ substrates. In general, the AET that was a positive charge with $NH^{3+}$ was strongly combined under the electrostatic interaction with DNA molecule which had to be a negative charge. The DNA molecules could be easily aligned between Au electrodes coated with AET. The structures of the DNA molecules were investigated using AFM(Atomic force microscope), they were changed from single types to bundle according to the AET concentrations.

• Journal of the Korean Chemical Society
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• v.63 no.1
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• pp.45-50
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• 2019

Because arsenic (As) is a chemical substance toxic to humans, there have been extensive investigations on the development of As detection methods. In this study, the electrochemical determination of As on nanoporous gold (NPG) electrodes was investigated using anodic stripping voltammetry. The electrochemical surface area of the NPG electrodes was controlled by changing the reaction times during the anodization of Au for NPG preparation, and its effect on the electrochemical behavior during As detection was examined. The detection efficiency of the NPG electrodes improved as the roughness factor of the NPG electrodes increased up to around 100. A further increase in the surface area of the NPG electrodes resulted in a decrease of the detection efficiency due to high background current levels. The most efficient As detection efficiency was obtained on the NPG electrodes prepared with an anodization time of 50 s. The effects of the detection parameters and of the Cu interference in As detection were investigated and the NPG electrode was compared to flat Au electrodes.