bluuebunny/crossref_metadata_2025 huggingface dataset:
One-Step Process to Fabricate Transparent Polymer Gel Electrolyte for Electrochromic Window
Authors: Lee Minji , Kim Hyungsub , Choi Dahyun , Chu Wonshik , Chun Dooman , Lee Caroline Sunyong
Published: February 2020

All-solid-state electrochromic device (ECD) has received considerable attention with the development of energy-efficient and high stable smart windows. Polymer electrolyte is necessary for ECD instead of liquid electrolyte to prevent leakage because of its safety and durability in real outdoor condition. Therefore, research has been focused on polymer systems containing PMMA [1], PEO [2], UV-crosslink network [3] and etc. However, several drawbacks i.e. yellowish color, haze, and complex multi-step process still remain. To overcome these problems, we tried to improve optical transparency of polymer electrolyte with a simple and easy fabrication method.

In this research, we prepared a transparent and free-standing gel polymer electrolyte with excellent mechanical flexibility and elongation in one-step process. Three-dimensional acrylate crosslinking network has formed directly through UV irradiation under co-presence of the PVdF-HFP and LiClO4 salt. To obtain optimum composition, variables including mono-, di-acrylate oligomers, PVdF-HFP, and plasticizers were controlled. Electrolyte was analyzed with regard to physical and chemical characterization using SEM, FT-IR, DSC, Tensile test, and ion conductivity measurement, etc. In order to fabricate electrochromic device, electrochromic film was deposited by Nano Particle Deposition System (NPDS), which is a facile dry-deposition method to coat ceramic powders using high impact energy when the collisions between particles and substrate occur [4]. Electrochromic performance of the fabricated cell was evaluated by in situ UV-Vis spectroscopy and electrochemical analysis techniques, such as Electrochemical Impedance Spectroscopy(EIS), and Cyclic Voltammetry(CV), etc.

Finally, it was confirmed that extremely clear ion conducting membrane was easily fabricated in one-step and successfully applied to ECD at ambient temperature. The transmittance of the polymer electrolyte showed over 80 % and the fabricated ECD cell with polymer electrolyte exhibited its transmittance change greater than 50 % at its wavelength of 800 nm under 3 V which shows almost similar performance of the cell using liquid electrolyte. Therefore, we have developed one-step process to fabricate highly transparent and free-standing polymer electrolyte, to obtain high performance electrochromic device.

[1] J. Phys. Chem. B, 2009, 113, 8006–8010

[2] Scientific Reports 2016, 6, 19892

[3] Membranes, 2012, 2, 687-704

[4] Applied Surface Science, 2016, 377, 370–375
(Invited) Solution-Processed Nanostructured Electrochromic Materials: Preparation and Application
Authors: Ma Dongyun , Xu Zhongping , Wang Jinmin
Published: February 2020

Electrochromic materials and devices can change color under applied potentials, which are widely studied for applications in energy-saving smart windows, rearview mirrors, displays, and so forth. The operation of electrochromic materials and devices involves the gain or loss of electrons and simultaneous insertion/extraction of ions with opposite charges to balance the internal electric fields. The performance is therefore limited by kinetics of charge transport in electrochromic materials as well as ion migration in electrolytes, materials and at their interfaces. Nanostructured electrochromic materials have an extremely short charge transport distance facilitating charge transport in electrochromic devices and large specific surface area improving the contact with electrolytes, which may result in enhanced electrochromic properties. By using solution-processed technology, we prepared nanostructured electrochromic materials, including hydrothermally synthesized WO3 nanorods, NiO nanosheets, flower-like NiO micro-nanostructures, well-adhesive WO3 and Prussian blue films directly grown on transparent conductive glass, electrodeposited Prussian blue film. Electrochromic devices based on these materials show their potential applications in smart windows, displays and self-rechargeable batteries.
Modification of Thin Films of Poly(3,4-ethylenedioxythiophene) for Enhanced Electrochromic Performance
Authors: Kao Chung-Min , Hu Chih-Wei , Vittal Ramamaurthy , Ho Kuo-Chuan
Published: February 2020

In this work, a thin film of poly(3,4-ethylenedioxythiophene) (PEDOT) was modified with chloride anions (Cl-), intending to enhance its electrochromic (EC) performance. The modified film of PEDOT was prepared by electrochemical polymerization in an aqueous solution, containing the monomer and Cl-. The resultant film is abbreviated as PEDOT-Cl. The PEDOT-Cl film prepared in the aqueous solution exhibited multi-color EC properties, with reference to those of bare PEDOT film prepared in the organic solvent, acetonitrile. The PEDOT-Cl film showed two electrochromic states in the visible region, upon the application of voltage from 0.3 ~ -0.8 V (vs. Ag/Ag+); the modified film exhibited light blue and red brown at the oxidized state and reduced state, respectively. Normally, the pristine PEDOT thin film can be switched from deep blue to light blue; however, the phenomenon we observed here is dramatically different from what have been reported in the literatures, presumably due to the doped cloride ions inside the PEDOT film. The enhanced electrochromic properties of the thin film of PEDOT-Cl have apparently something to do with the incorporation of Cl-. The transient transmittance of the PEDOT-Cl film gave a transmittance window (ΔT) of 31% at 500 nm. For an active area of 2.0 x 2.0 cm2, the switching times of the PEDOT-Cl film were estimated to be 4.4 and 4.0 s for bleaching and coloring, respectively. The coloration efficiency of the PEDOT-Cl film was calculated to be 215.3 cm2C-1 at 500 nm.

Figure 1
Optimization of NiO Thin Films By Sol-Gel for Electrochromic Properties
Authors: Zrikem Khawla , Da Rocha Mathias , Ait Aghzzaf Ahmed , Amjoud M'Barek , Mezzane Daoud , Rougier Aline
Published: February 2020

Among electrochromic materials, nickel oxide, NiO, has received significant attention due to its anodic coloration leading to neutral color devices when combined with WO3 [1]. In the past few years, few authors pointed out the key role plays by the film stoichiometry on its electrochromic (EC) properties [2, 3]. In particular in our group, we reported a strong correlation between electrohromic properties and the nickel/oxygen content in Ni1-xO thin films deposited by RF Sputtering [4]. Especially a departure from the stoichiometry leads to unexpected EC properties in electrolytes with no small cations. Such non stoichiometry, leading to unusual properties can also be induced by dopant addition.

Herein, NiO based thin films were fabricated by sol-gel method combined with spin coating technique onto ITO/Glass substrate. The influence of molarity, solvents, stabilizing and the nature of the final treatment on the structural, morphological, electrical and optical properties of NiO based thin films was studied and correlated to their EC behavior. Overall films are poorly crystallized. The films synthesized by methanol as solvent, triton 100X as stabilizer and treated by UV light thin film exhibit the highest capacity in KOH based electrolyte and the highest optical contrast. Lithium addition was investigated for improved p-type conductivity. Finally, the integration of sol-gel NiO thin films in full devices (WO3/Li-based electrolyte/NiO) will be discussed.

[1] H. Moulki, D.H. Park, B.K. Min, H. Kwon, S.J. Hwang, J.H. Choy, T. Toupance, G. Campet, A. Rougier, Electrochimica Acta, 2012, 74, 46

[2] R.T. Wen, C.G Granqvist, G.A. Niklasson, ChemElectroChem 2016, 3(2) 266.

[3] X. Song, G. Dong, F. Gao, Y. Xiao, Q. Liu, X. Diao, Vacuum 2015, 111, 48.

[4] M. Da Rocha, A. Rougier, Electrochromism of nonstoichiometric NiO thin film: as single layer and in full device, Applied Physics A, 2016, 122(4), art. n° 370, 7.
Penetrating Nanoelectrodes for Stimulation of Single-Cells
Authors: Garde Komal , Aravamudhan Shyam
Published: February 2020

In this paper, we report on the development of two nanoelectrode geometries, namely nanopillar and nanofin to interface with live neuronal cells. Electrical stimulus is delivered via penetrating nanoelectrodes in order to stimulate live PC12 cells. The paper also reports on the time dynamics of cell penetration process using the nanoelectrode. We show that (a) nanoelectrodes of optimized size and shape can penetrate into PC12 cells without any loss of cellular function and (b) electrical stimulus can be applied through the penetrating electrodes in order to stimulate or differentiate PC12 cells without the use of conventional growth factors, genetic manipulators, cytokines or other chemical reagents. The nanoelectrodes (nanopillars) are designed to overcome the trade-offs between electrode impedance and electrode size. Compared to conventional 3x3 array of 150 nm diameter nanowire electrodes, the current 50-150 nm nanoelectrodes have reduced electrode impedance by factor of at least 20 due to a large capacitance and small charge transfer resistance, while maintaining minimal cell damage. The fabrication of nanoelectodes starts from silicon on insulator (SOI) substrate, followed by a series of lithographic patterning, deposition and etching steps including focused ion beam (FIB) ion-milling. The precise placement of cells on the nanoelectrodes is a challenging process. After surface functionalization with silane coupling (uncoated Si) or thiol chemistry (Au nanoelectrodes), non-contact microprinting method using an inkjet printer was also used to place cells on the nanoelectrodes. For cell differentiation, pulsed DC stimuli with monophasic 100 ms square pulse of 100 mV/cm field strength and 1 Hz frequency are applied. In order to validate this differentiation process, gene expression markers and morphological changes are monitored. Figure 1 shows the dynamics of the cell penetration process over time, recorded at 5 minutes to 5 hours. Figure 2 shows fixed SEM images of differentiated cells being penetrated by the nanoelectrodes without any loss of cellular function. Additionally, it is evident (figure 3) that the nanoelectrodes are clearly assessing the interior of the cells’ cytosol. This image was taken after FIB milling of one half of the electrode-cell interface.

Figure 1
Novel Films Based on Inexpensive and Readily Available Materials for Use As a Hydrocarbon Sensor
Authors: Sebastian Holly Bri , Pilonieta Roberto , Mayall Robert Matthew , Birss Viola , Bryant Steven
Published: February 2020

One of the most commonly cited arguments against erecting and using pipelines to transport oil and gas, is that of the potential leaking of these compounds into the environment. These leaks can infiltrate water systems, kill wildlife and contaminate soil. In many instances, pipeline owners are unaware of leaks. In Alberta (Canada), it was found that, on average, it can take as long as 48 days to respond to and isolate a pipeline leak (according to the Alberta Energy Regulator)1. In Canada alone, there are an estimated 825,000 kilometers of pipeline infrastructure already in operation2. The depth of cover for pipelines varies, depending on where the pipeline is located, creating significant challenges when monitoring pipelines for leaks. Identifying gas seepages is significantly easier than liquid leaks, as gases rise up out of the ground. Liquids, on the other hand, seep down into the ground, compounding the issue. In this work, a novel fabrication process for a single use, low-cost liquid hydrocarbon sensor has been developed. The process is simple, and the materials are readily available and low cost. The film has controllable hydrophilicity and can present amphiphilic properties, as well as strong electrical conductivity.

We have successfully applied this film as a sensor for the presence of hydrocarbons that could be found in the event of a leak from an oil pipeline. The sensor responds rapidly to alkanes of varying lengths and has also shown strong responses to both functionalized hydrocarbons and aromatics. The sensor is both inexpensive and easy to manufacture, with scale-up being a matter of simply using a larger container for the synthesis. The sensor does not respond to water, a potential interferent for a sensor placed in soil, and has shown good stability towards dessication and long-term storage. Combined, this supports the application of such a device for the field detection of organic compounds commonly found in the presence of an oil spill or pipeline leak.
A Photovoltaic Device Based on PbS Quantum Dots
Authors: Ghomian Taher , Farimand Samaneh , Choi Jin-Woo
Published: February 2020

This abstract presents a solution-processed photovoltaic device based on the PbS (lead sulfide) colloidal quantum dots (CQDs). A simple fabrication method at room temperature makes the solution-processed photovoltaic devices be a suitable cost effective alternative. In addition to simplicity in the fabrication method, a key advantage of photovoltaic devices based on PbS colloidal quantum dots is the tunability of the absorption spectrum by controlling the size and shape of the PbS quantum dots [1].

The structure of the photovoltaic device is shown in the figure. Active area is composed of a superlattice of doped PbS quantum dots sandwiched between two electric contact layers. The active area makes a Schottky contact with an electrode having low work function such as aluminum on one side and an Ohmic contact with a transparent electrode such as ITO (Indium Tin Oxide) on the other side. Absorbed photons in the active layer generate neutral excitons in the PbS quantum dots, and subsequently charge dissociation takes places in the neutral region due to the internal electric field at the Schottky contact. Photogenerated electrons and holes flow toward the Al and ITO contacts, respectively.

Fabrication process starts with the deposition of doped colloidal PbS quantum dots on an ITO coated glass substrate by a layer by layer (LBL) method in an inert condition at room temperature. The process is followed by aluminum deposition on top by physical vapor deposition. Fabricated photovoltaic device illustrates promising sensitivity to both entire visible and portion of infrared spectrum of sun light. Since both device structure and fabrication process are simple and process can be done in room temperature, fabrication on the flexible substrates is also feasible.

References

[1] C. de Mello Donega, "Synthesis and properties of colloidal heteronanocrystals," Chem. Soc. Rev., vol. 40, pp. 1512–1546, 2011.

Figure 1
Tailored Nickel Oxide Nanorods Via Hydrothermal Growth for Gas Sensors and Electrocatalysts
Authors: Chung Yoonsung , Lee Eunji , Lee Doohee , Yoon Jaesik , Lincoln Christopher , Prorok Bart Charles , Woo Sungpil , Yoon Youngsoo , Kim Dong-Joo
Published: February 2020

Nickel oxide, a p-type wide-bandgap semiconductor, is a very attractive material for various applications including catalysts, electrode materials for lithium ion batteries and fuel cells, electrochemical capacitors, electrochromic thin films, biosensors, and gas sensors.  

In nanoscience research the morphology-controlled synthesis is a crucial issue to change and improve properties of materials at nanoscale. Among many methods, the solution-based chemical process has developed into a promising technique because it allows to easily tune morphologies with changing experimental parameters. To achieve different aspect ratios of NiO nanostructures, a NiCl2-Na2C2O4-H2O hydrothermal system with polyethylene glycol, ethylene glycol, and glycine as surfactant was suggested. However, their work was limited to form a nanowire bundle during the chemical reaction. Therefore, a solution system to obtain a wider range of morphological features of NiO needs to be developed. In addition to synthesis of NiO nanostructure, its coating to desired substrates is important. As a possible pathway, electrophoretic deposition (EPD) can be considered because of its high versatility and low cost equipment. EPD process can also be applied to various types of substrates such as fibers, cloths and complex shaped materials. Such a flexible, soft and nonfragile substrate has been explored for flexible and wearable functional devices. 

In this study, nanostructured nickel oxide is synthesized using a hydrothermal method and tailored by triethanolamine. The structural properties of the nickel oxide particles were analyzed by using SEM and XRD. Strong dependence of the triethanolamine on NiO nanorods was found and their mechanism was investigated. For the fabrication of the devices, EPD of tailored nickel oxide was then used to construct nickel oxide electrodes on polyimide films for gas sensing measurements and carbon papers for electrochemical measurements. The morphology-controlled gas sensing properties of NiO were investigated with VOC gases. The performance of NiO for gas sensors were evaluated in terms of sensitivity and selectivity. The mechanism of p-type NiO for gas sensors is discussed in details. For nickel oxide catalysts, the urea electrooxidation in alkali medium were investigated and evaluated by cyclic voltammetry and chronoamperometry. In order to improve electrocatalytic activities, nickel oxide decorated by nickel and cobalt composite structures were also investigated.  

The work was partially supported by the KIET Evaluation and Planning (20158520000210) grant funded by the Korea Government Ministry of Trade, Industry and Energy and Agency for Defense Development (ADD) as global cooperative research for high performance and light weight bio-urine based fuel cell (UD160050BD).
Thin Layer Disposable Flow Cells As (Spectro)Electrochemical Detectors in FIA Systems
Authors: Fanjul Bolado Pablo , Kanso Hussein , González García María Begoña , Hernández Santos David
Published: February 2020

In this work different flow-cell electrochemical platforms where channel slide is directly mounted over the screen-printed electrodes are proposed. Flow-cells for screen-printed electrodes are usually wall-jet type but due to the transparent cover that defines the channel (height 400μm, and 100μL of volume), a thin layer is formed over the electrochemical cell. The cover’s transparency allows the detection of air bubbles inside the cell. The injection is done through an “in-line luer injection port” where sample volume can be easily controlled by operator through a Hamilton syringe.

Different configurations of the electrodes in the electrochemical platform can be used, rectangular or circle electrodes, only a working electrode or dual sensors as well as different materials such gold, platinum or carbon, etc.

These electrochemical flow cells combining with the adequate holder and fittings allow us to have an user friendly FIA system with a great possibility of applications based on electrochemical or spectroelectrochemical detection, depending on the set-up used to carry out the measurement.

Here in several samples of the use of these thin layer electrochemical flow-cells as transducers of enzymatic sensors or as detectors are presented showing a good performance, simple operability and effectiveness of working in FIA systems.

The work was carried out in the framework of the European project “BIOENERGY”. This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 607793”.
A Printed Capacitor with Carbon Nanotube Electrodes for Energy Storage
Authors: da Costa Tallis H. , Choi Jin-Woo
Published: February 2020

Capacitor-type energy storage is becoming an attractive option as it can be fabricated with simple methods and allows integration into a flexible substrate for wearable applications. Currently, there is a need for reliable and simple fabrication methods that take into account the characteristics of nanomaterials for their controlled deposition. Inkjet printing presents advantageous features because it allows solution-processed materials to be printed with high accuracy and resolution. Therefore, a number of patterning steps can be performed sequentially, thus minimizing the need for lithography or other fabrication methods. We have fabricated a fully inkjet-printed capacitor as energy storage for wearable sensors.

We have explored several configurations of capacitors. A parallel plate capacitor is composed of carbon nanotubes that are inkjet printed on PET film to form a compact conductive mat structure. The assembly is composed of two layers of carbon nanotubes separated by a dielectric layer of polymer, as illustrated in the figure (left). The advantage of this design is that it does not require an electrolyte to function and can be printed on flexible substrate such as PDMS. On the other hand, a supercapacitor configuration achieves higher energy storage, power density, and is also of simple construction [1]. The supercapacitor type is constructed by printing carbon nanotubes and subsequently by electrodepositing a metal oxide. It is finally assembled with a separator membrane for ion conduction and filled with electrolyte, as shown in the figure (right). The charge storage based on the redox reactions of the metal oxide is mainly responsible for its capacitance [2]. The energy storage and power density of the supercapacitor are greatly improved with the use of carbon nanotube electrodes, because of the high surface area of carbon nanotubes.

We demonstrate the capacitor as a charge storage component that is integrated in a wearable system. Moreover, our inkjet printing system precisely prints a network of carbon nanotubes. We show that the inkjet-printed capacitors provide a rapid and reliable fabrication for wearable systems.

References

[1] M. Zhi, C. Xiang, J. Li, M. Li, and N. Wu, Nanoscale, 5, 72–88 (2013).

[2] X. Zhang et al., ACS Nano, 5, 2013–2019 (2011).

Figure 1
Tri-Block Copolymer Assisted Synthesis of Highly Porous Pt-Pd Bimetallic Nanoassemblies
Authors: Chang Fang-Ching , Li Yen-Cheng , Wu Ren-Jye , Huang Jing-Wen , Hwang Jenn-Yeu , Chen Chun-Hua
Published: February 2020

Highly-porous and -uniform spherical nanoassemblies comprising a variety of Pt and Pd bimetallic primary nanostructures have been successfully synthesized via a facile chemical reduction approach with the assistance of a face-centered-cubic packed tri-blocking copolymer, Pluronic F127 (PEO100PPO70PEO100), which not only acts as the spherical micro-reactors for keeping unique assembling dimensions, but significantly influences the reduction dynamics as well as the morphology of building blocks. Building blocks with elliptic, slender and flat petal like morphologies can thus be achieved by means of the precisely controlled atomic ratio of Pd/Pt and respectively exhibit distinct UV-visible extinction spectra. According to the characterizations of high-resolution transmission electron microscopy, high angle annular dark field images, energy-dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy, we evidently identify that the central part of the present very special spherical nanoassemblies is Pd rich whereas the outer shell is Pt rich, mainly resulted from the difference in reduction potential for these two precursors. The detecting limitation of malachite green oxalate utilizing surface-enhanced Raman scattering (SERS) technique could approach 1 ppm or less for the flat petal like specimen. We believe that the newly designable metal growth approach described here will trigger the facile fabrication of advanced multi-metallic nanoassemblies with craving properties in the near future.
Au Nanoparticles Decorated Hollow Pt-Pd Nanoassemblies As High Performance SERS Chemical Sensors
Authors: Huang Jing-Wen , Chang Fang-Ching , Chen Chun-Hua
Published: February 2020

We have successfully synthesized a series of unique Au nanoparticles decorated hollow Pt-Pd nanoassemblies via a facial tri-block copolymer based approach for the prior formation of porous Pt-Pd nanoassemblies as the base architecture and the subsequent electrochemical treatment with HAuCl4 for fabricating extremely hollow Pt-Pd spherical shells with densely decorated Au nanoparticles. The surface-enhanced Raman scattering (SERS) performance for malachite green oxalate and pesticide such as the parathion and thiabendazole will be extensively investigated and discussed. The developed two-step polymer based approaches and the fabricated novel Au nanoparticles activated tri-metallic hollow nanoassemblies as well as their SERS performance not only provide insight of the relevant phenomena during processing and sensing, but are able to be directly applied for biochemistry, chemical analysis, food safety and environmental monitoring.
NAD-Glucose Dehydrogenase Immobilized on Gold Via Iron-Sulfur Based Molecular Wires for Biosensing Applications
Authors: Mahadevan Aishwarya , Fernando Sandun
Published: February 2020

Immobilization of NAD-dependent redox enzymes on electrode surfaces has been widely reported for the construction of enzymatic biosensors for detection of various biomolecules in different industries. Molecular wiring of such redox enzymes facilitate an efficient electron transfer by connecting redox center of the enzyme with the electrode surface. Iron-sulfur complexes are known for being the first-link between protein and the mediating molecules in the mitochondrial electron transport chain to abstract electrons from NAD+. The application of different iron-sulfur molecules as molecular wires to mediate electron transport between NAD-dependent glucose dehydrogenase (NAD-GDH) and gold electrode surface (i.e. a glucose bioanode) was studied. Methodology for fabrication and characterization of iron-sulfur based glucose bioanodes at different construction stages were described. The electron transport mechanism between NAD-GDH and gold electrode surface via iron-sulfur based molecular wires was investigated using amperometric analyses in the presence of glucose.
Cyclic Voltammogram of Paclitaxel Nanoparticles
Authors: Miller Steven T , Lee Dongwon , Prabhulkar Shradha , Williams Gary W , Trieu Vuong N
Published: February 2020

Background: Successful nanoparticles formulations include Abraxane® (an albumin bound nanoparticle paclitaxel), Genexol-PM® (a polymer bound nanoparticle paclitaxel), and Doxil®. At LipoMedics we have developed a unique nanomedicinization process of water insoluble drug for intravenous administration using combination of solvents and polymers. The polymers can be simple phospholipid or synthetic diblock polymer or complex protein such as albumin. Electrochemistry was used to understand the molecular organization of these nanoparticles and biosensor built to support the in process monitoring of this pharmaceutic.

Materials and Methods: Nanoparticle synthesis was conducted using a two step method whereby the drug is first emulsified in presence of solvent and then nanofabricated in presence of polymer. Nanoparticle size and zeta potential were measured using a Malvern ZS DLS system. The formulation was subjected to serial filtration using 1.2µm, 0.8µm, 0.45µm and 0.2µm syringe filters. The drug incorporation/loading was measured using ELISA. Electrochemical properties of the formulation were measured using screen printed carbon nanotube (CNT) electrodes from DropSens and a PGSTAT204 Autolab Potentiostat from Metrohm. The drug being evaluated in this study is paclitaxel- a water insoluble drug that can only be solubilized in Cremophor EL for intravenous administration. Only nanomedicinization allowed paclitaxel to be formulated without solvent.

Results:A series of stable nanomedicinized paclitaxel formulations were created using chloroform or ethanol as solvent and phospholipid or albumin as polymer. Each formulation exhibited a distinct cyclic voltammetry (CV) scan. The CV scan was highly dependent on the polymer used. Monolayer and bilayer phospholipids behaved similarly as polymer with or without paclitaxel. Increasing the loading of these phospholipid nanoparticles caused a shift from profiles of high capacitance material to profiles of low capacitance material.

Discussion: Capacitance of a carbon-based electrode consists of two major components: the electrical double layer capacitance due to the electrostatic attraction of charged carbon surfaces to electrolyte ions and the pseudocapacitance due to the Faradic reactions of electroactive species on the carbon surfaces. During electrochemical evaluations, the nanoparticles were treated as ionic liquid capacitance material. Low capacitance is suggestive of weakened charge accumulation in the electrode - electrolyte interface which depends on the mesoporosity and electrolyte accessibility of the capacitive material.
Application of Fin Structure Factor to Reduce the Body Effect in 20 nm DRAM Cells
Authors: Jung IL-Woo , Kim Hyoung-Sub , Choi Byoung-deog
Published: February 2020

Body effect is the key characteristic of DRAM cell transistor. In conventional planar transistor, length and width affect the body effect. But in recent buried channel structures, the fin structure affects the properties of transistor. In this paper, we investigated the effect of fin structure on the body effect in a DRAM cell. And we suggested a structure for reducing the body effect. In order to measure the body effect in DRAM cell, nondestructive measurement method was used. It uses a memory test system for fast, massive, nondestructive measurement. Newly developed method can measure 100,000 DRAM cell body effects in two minute, without sample damage. Since this method does not damage the sample during the measurement, there is no problem in making a TEM sample. After the measurement, we compared the body effect and the fin dimension. Fin height, fin width, fin top width, fin angle was measured to define the fin dimensions. Of the four dimensions, the fin height had a correlation with the body effect. The rate of change of the body effect according to the fin height was -10mV/V/nm. In the DRAM, the body bias is generated by a bias generator. And since this generator is affected by voltage and temperature, the body bias can vary depending on this environment. When the body bias changes, the threshold voltage of the DRAM cell changes. This result is bad for the characteristics of DRAM. So, we have to make the DRAM with a small body effect. In this paper, we propose to increase the fin height for a small body effect.

Figure 1
Optical Characterization of CaCu3Ti4O12 thin Films
Authors: Skaria Giji , Sundaram Kalpathy B
Published: February 2020

CaCu3Ti4O12 is in the family of perovskite materials that may have potential electrical as well as optical applications. In this study, we have focused on the optical properties of the films. These films are deposited by RF magnetron sputtering process using CaCu3Ti4O12target. The films are deposited under varies deposition conditions that include argon gas flow ratios, process pressures and substrate temperature. The transmission and reflection properties are performed using the UV-Visible spectrophotometer to extract the bandgap and refractive index of these films.
Interaction of Thiol Ligands with Gold in Electrocatalytic CO2 Reduction
Authors: Cheng Xun , Fang Yuxin , Xu Ye , Flake John
Published: February 2020

The electrocatalytic CO2 reduction reaction (CO2RR) has the potential to produce fuels and chemicals from a renewable feedstock: It can be used as an energy carrier to store energy generated from intermittent, distributed sources such as wind and the sun. It can also be used as a renewable source of carbon for chemical production. The key to enabling these uses of CO2 is to maximize the selectivity and energy efficiency of electrocatatlytic CO2RR toward the desired product. We have taken inspiration from biological enzymes that catalyze CO2RR (e.g. carbon monoxide dehydrogenase) and attempt to mimic their active sites by functionalizing Au electrodes with a series of organic thiol ligands, to seek opportunities to potentially break the constraints imposed by scaling relations. Our work shows that different thiol species can enhance the activity for the formation of different CO2 reduction products. For instance, 2-merceptanpropionic acid effectively reduces the yield of CO to negligible amounts and enhances H2 evolution to nearly 100% faradaic efficiency. 2-phenylethanethiol, on the other hand, strongly promotes CO evolution and suppresses H2 evolution, whereas 4-pyridinylethanemercaptan boosts the faradaic efficiency toward formate by suppressing CO formation.

We have performed detailed density functional theory calculations and theoretical modeling in conjunction with our electrochemical experiments to elucidate the role of the thiol ligands in CO2RR on Au. We find that thiol ligands exist primarily as thiolates on Au in the potential range relevant to CO2RR. They can readily reconstruct Au surfaces at ambient conditions, leading to a higher proportion of under-coordinated sites where the activity of CO2 reduction is significantly promoted but the effect of under-coordinated Au sites on H2 evolution is less prominent. In addition, different functional groups on thiols create different local reaction environments on the Au electrode resulting in different product speciation. Spectroscopic evidence for thiol and non-thiol ligands adsorbed on Au will also be discussed; for instance, S-binding and C-binding ligands exhibit distinct vibrational signatures with different electrochemical stabilities. Overall our study suggests that functionalization of Au holds significant promise for promoting CO2 reduction and achieving different product selectivity with appropriately chosen thiol-based ligands.
Optical Reflectance Spectroscopy of Spin-Coated Multilayered ZnO and Al:ZnO Thin Films
Authors: Buckley Darragh , McCormack Robert , McNulty David , Zubialevich V.Z. , Parbrook Peter J. , O'Dwyer Colm
Published: February 2020

Transparent conducting oxides are unique in their ability to be incorporated into a variety of electronic devices such as LCDs, photovoltaic cells and LEDs. This unique ability is due to the oxides having wide band gaps (Eg
~ 3 eV - 4 eV) which gives high transparency (> 80% in visible region) and effective conductivity (>103 Ω-1cm-1) which can be achieved through the introduction of dopants. Zinc oxide is a well-known material of interest due to its wide band gap (Eg
~ 3.3 eV at 300 K) and also for the variety of methods by which it can be processed. Moreover, ZnO is readily able to alloy with other metals in the oxide form and has a lattice that can facilitate interstitial doping. This gives ZnO a key role in the area of optoelectronics, metal oxide thin films and thin film transistor (TFT) technologies.

We show the visible and near-infra red (VIS-NIR) light spectroscopy of ZnO and Al:ZnO multi-layered thin film structures grown on oxidized silicon substrates. Using optical interference, the thickness of the multi-layered deposited ZnO and Al:ZnO can be determined. Using angle-based reflectance spectroscopy measurements and a method derived from reflectivity of dispersive, non-absorbing materials, the optical thickness of thin films samples are calculated. These calculations show an excellent agreement with the actual thickness of ZnO samples with a margin of error of <4% for a 20 layer (500 nm thick) film and <1% for a single-layer ZnO film. This work also investigates the anti-reflection properties of ZnO and Al:ZnO thin films at a variety of angles of incidence. Results show that film’s minimum reflectivity (< 8%) can be tuned in the visible frequency range, based on number of iterative layer depositions and subsequent thickness.
Formation and Evaluation of Cyanide from Cyanide Free Solution By Electroplating
Authors: Kitago Takuya , Tamaki Kazuma , Mizuhashi Shoei , Koiwa Ichiro
Published: February 2020

In recent years, environmental problems are regarded as important in all industries. Especially in the plating industry, cyanide, which is a toxic substance is strictly regulated, plating bath with cyanide and plating bath without cyanide are strictly distinguished. This is carried out on the premise that cyanide is not generated from a plating bath without cyanide. As such cyanide compounds are severely regulated, there are adverse effects such as cyanide spill accidents, waste water treatment must be done, so stop using cyanide compounds and use raw materials and manufacturing methods not containing cyanide compounds it tends to be. However, when defected samples plated from bath without cyanide was analyzed by using thermal desorption spectrometry (TDS), The bath with synthesized cyanide was removed by activated carbon treatment, but it was confirmed that cyanide was formed even in a plating bath without cyanide. The case where cyanide was detected from a cyanide-free plating bath was also reported in the 1980's,1) it had reported that it was possible to synthesize cyanide when carbon source and nitrogen source were present and conditions were set there.2) It was also reported amines and nitrite ion reacted and formed cyanide.3) We have reported that the cyanide was synthesized in the solution containing glycine.4) All plating baths were adjusted to 0.2 mol/dm3. Bath pH was adjusted at 12.0. Plating conditions were as follows, anode was nickel, cathode was platinum, a current density was controlled from 10 A/dm2 bath temperature was 60 °C. A electrolysis time was controlled from 60 min. Cyanide concentration was determined by the pack test and the picric acid method. The pack test is used to determine the presence or absence of cyanide. The picric acid method was used to determine cyanide concentration in the bath. Figure 1 showed effect of chemicals, amine and amino acid, on amount of synthesized cyanide. However, the amount of cyanide produced by amines was as low as 0.1 ppm for N-methylethylene-diamine (N-MEDA) and 4.7 ppm for N-ethyl ethylene-diamine (N-EEDA). Among the amino acids, without glycine the maximum of β-alanine was about 6.6 ppm, and the minimum was less than 0.1ppm. However, when a glycine bath was used, cyanide of 50.9 ppm could be measured. Glycine bath was found to be easy to produce cyanide.

1) M.Nonomura, Jitsumu Hyomen Gijyutsu, 32(1), pp11-20 (1985) [in Japanese]

2) M.Hara and T.Ishikawa, Mizusyorigijyutsu, 22(3), pp215-218 (1981) [in Japanese]

3) T.Koshimizu, K.Takamatsu, M.Kaneko, S.Fukui and S.Kanno, HyGienic Chemistry, 21(6), pp326-329 (1975) [in Japanese]

4) S.Mizuhashi, T.Arakawa, N.Watanabe, S.Koike, M.Urano, K.Maejima, N.Hirashita and I.Koiwa, Electrochemistry, 84(6), pp394-397 (2016) [in Japanese]

Figure 1
Electrochemical and Structural Investigation of Metal-Electrodes for an Energy-Efficient CO2-Reduction Process
Authors: Bienen Fabian , Wagner Norbert , Friedrich K. Andreas , Kopljar Dennis , Löwe Armin , Klemm Elias
Published: February 2020

Sustainable conversion of CO2 to formic acid by an electrochemical process, often called ‘artificial photosynthesis’ due to the O2 produced at the counter electrode, can help to reduce the CO2 emission from industrial production sites. The produced formic acid can be used for a wide variety of applications in the pharmaceutical and chemical industry or it can be stored and converted back to electrical energy via a fuel-cell like device. Thus, this process can help to stabilize the power-grid during peak-times by providing control power. The basic idea of this process is the well-known concept of power to chemicals to store energy and additionally reduce CO2 emissions.

By using carbon supported Sn/SnOx gas diffusion electrodes (GDE), an efficient electrochemical conversion of CO2 to formic acid can be realized. The porous structure of the GDEs strongly affects the electrochemical performance of these GDEs. In detail, the intrusion of the electrolyte and CO2 into the electrode has a considerable influence onto the cathodes physicochemical characteristics. The intrusion behaviour of the electrolyte was investigated to determine the inner hydrophobicity, by using a combination of the Lucas-Washburn and Owens-Wendt method. To further investigate the penetration behaviour a custom-made cell was used to measure the capillary pressure.

Additionally iridium oxide based electrodes are used as anodes for the oxygen evolution reaction (OER) and optimized regarding their electrochemical performance. With these anodes and the above mentioned GDEs a continuous working full-cell set-up can be realized. The full-cell set-up was investigated by polarisation- and electrochemical impedance spectroscopy-measurements.
Exploring the Energetics of the Lithium Ion-Organic Carbonate Interaction: A Temperature-Dependent FTIR Study
Authors: Woodard Kaylee , Fulfer Kristen D'Ann , Kuroda Daniel G
Published: February 2020

Lithium ion batteries are now essential to the portable energy storage industry. However, this technology still faces many problems associated with safety and energy storage density. While the energy storage density is related to all components of the battery, its safety concerns are mostly associated with the lithium ion electrolyte. Typical lithium ion electrolytes are composed of a lithium salt in a mixture of organic carbonate solvents of both linear and cyclic structure. Specifically, the industry standard, referred to as the generation 2 lithium ion battery electrolyte, is composed of ~1M lithium hexafluorophosphate salt in a mixed ethylene carbonate/ethyl methyl carbonate solvent at a volume ratio of 3:7 and has the highest conductivity reported for a carbonate-based electrolyte so far. However, the underlying reasons for realizing higher conductivity and better electrochemical cycling in specific carbonate mixtures are unknown. By further characterizing the interactions between the lithium ion and the organic carbonates, a more complete understanding of these electrolytes and how they function within the battery can be obtained. In this study, we have characterized the energetics of the lithium ion-carbonate interaction for several carbonates, both linear and cyclic in structure using temperature-dependent infrared spectroscopy. Our studies show new insights into the interplay between the energetics of lithium solvation.
Theoretical Uv-Vis Spectral Fingerprints for Li-S Reaction Intermediates in an Ether Based Electrolyte
Authors: Wang Dunyang , Pascal Tod , Balsara Nitash P , Prendergast David
Published: February 2020

Li-S batteries have high theoretical capacity and specific energy density, but suffer from the dissolution of intermediate species, lithium polysulfides, into the electrolyte, leading to capacity fading and eventual battery failure. Research aimed at uncovering the elementary cathode reaction mechanisms during discharge/charge is critical to our ability to overcome this fundamental problem and design more efficient cells. Spectroelectrochemical methods, i.e. the coupling of spectroscopy with electrochemical measurements, has arisen as a powerful approach for studying Li-S reaction mechanism. In particular, Uv-vis spectroscopy has been one of the most useful techniques, because lithium polysulfides chemistry is sensitive to uv-visible light. However, interpretation of these measurements is difficult, due to a lack of fingerprints for each specific lithium polysulfide species, which cannot be easily isolated experimentally. Thus motivated by the need for spectral fingerprints, we simulated the theoretical spectra of each lithium polysulfides in a ether based solvent from first principles. Specifically, we sampled thermodynamically relevant ensemble structures in diglyme from first principal molecular dynamics simulations and calculated the associated absorption spectra using time-dependent density functional theory calculations. Our approach explicitly includes effects due to solvent screening, thermal reorganization and specific atomic interactions, which we show as critical for the unambiguous assignment of peaks in the experimental uv-vis spectrum.
Electrical Characteristics Improvement of NAND Flash Memory on Experiment to Replace 49BF2+ with 11B+ in Implantation of Ions
Authors: Choi Hyun-Mook , Roh Yonghan
Published: February 2020

As device size of NAND Flash is shrinking, the program and erase operations need the smaller number of electrons. So the importance of decreasing electron loss is getting increase. Because electron loss causes degradation of the device reliability. As has been discussed before, ion-implantation damage is important factor of NAND Flash fabrication process and device characteristics. Ion implantation damage makes interface trap so it causes electron loss in the device. The heavy ion mass (amu) ion-implantation process makes inevitably not only severe surface lattice damage and more defects in silicon (Si) surface but more thermal budget to recrystallizing. After RTA (Rapid Thermal Annealing) process, the unrestored defects exist at the silicon (Si) surface by heavy ion mass (amu) ion-implantation process damage. In this paper, we focus on endurance improvement characteristics between 49BF2+ ion implantation and 11B+ ion-implantation in 1X floating-gate (FG) NAND Flash cell. The interface trap density (Dit) decreases during initial and stress status by replacing 49BF2+ with 11B+. and erase Vth shift improves after 50k program/erase cycles. From experimental results, we found that the improvement by replacing 49BF2+ with 11B+ reduces interface trap at Si/SiO2 and improves endurance by reducing erase Vth shift in the program/erase cycles.