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Cho S.K.,Seoul National University | Cho S.K.,Center for Electrochemistry | Kim M.J.,Seoul National University | Kim J.J.,Seoul National University
Electrochemical and Solid-State Letters | Year: 2011

We evaluated the characteristics of methanesulfonic acid (MSA) as a supporting electrolyte in copper electroplating in terms of copper ion solubility, i-V behavior, and compatibility with additives for copper filling. Although the solubility of copper ion in MSA is higher than that in sulfuric acid, linear sweep voltametry analysis showed that the current density from MSA electrolyte was lower than that from sulfuric acid, due to its high solution resistance. Additives in MSA electrolyte behaved in the same way as in sulfuric acid, and the complete filling of damascene trenches and through silicon vias (TSVs) were obtained with PEG-Cl-SPS additives. © 2011 The Electrochemical Society. All rights reserved.

Hsu H.-Y.,Center for Electrochemistry | Ji L.,Center for Electrochemistry | Ji L.,University of Texas at Austin | Ahn H.S.,Center for Electrochemistry | And 3 more authors.
Journal of the American Chemical Society | Year: 2015

A liquid junction photoelectrochemical (PEC) solar cell based on p-type methylammonium lead iodide (p-MeNH3PbI3) perovskite with a large open-circuit voltage is developed. MeNH3PbI3 perovskite is readily soluble or decomposed in many common solvents. However, the solvent dichloromethane (CH2Cl2) can be employed to form stable liquid junctions. These were characterized with photoelectrochemical cells with several redox couples, including I3 -/I-, Fc/Fc+, DMFc/DMFc+, and BQ/BQ. (where Fc is ferrocene, DMFc is decamethylferrocene, BQ is benzoquinone) in CH2Cl2. The solution-processed MeNH3PbI3 shows cathodic photocurrents and hence p-type behavior. The difference between the photocurrent onset potential and the standard potential for BQ/BQ. is 1.25 V, which is especially large for a semiconductor with a band gap of 1.55 eV. A PEC photovoltaic cell, with a configuration of p-MeNH3PbI3/CH2Cl2, BQ (2 mM), BQ. (2 mM)/carbon, shows an open-circuit photovoltage of 1.05 V and a short-circuit current density of 7.8 mA/cm2 under 100 mW/cm2 irradiation. The overall optical-to-electrical energy conversion efficiency is 6.1%. The PEC solar cell shows good stability for 5 h under irradiation. © 2015 American Chemical Society.

Guo W.,University of Texas at Austin | Guo W.,Chongqing University | Duan Z.,University of Texas at Austin | Mabayoje O.,Center for Electrochemistry | And 7 more authors.
Journal of the Electrochemical Society | Year: 2016

Thin films of copper tungstate (CuWO4) have been prepared through electrodeposition and tested as the anode material for photoelectrochemical (PEC) water oxidation. We found that hydrogen-treatment over the synthesized CuWO4 at high temperatures led to enhancement in the PEC performance for water oxidation. The origin of this activity enhancement is attributed to the enhanced kinetics of electron-hole pair separation due to the increased carrier concentration induced by oxygen vacancy formation upon hydrogen-treatment. The incorporation of oxygen vacancies also resulted in enhanced light absorbance in the visible light region because they introduce shallow donors as predicted by first-principles calculations. Nevertheless, incident photon to electron conversion efficiency (IPCE) measurements indicate that light absorbed at long wavelength region after hydrogen-treatment is not successfully utilized to oxidize water. This report provides insights on the effect of hydrogen-treatment on the structural, optical, and electronic properties of CuWO4. © 2016 The Electrochemical Society.

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