bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Foldable Circuits and Organic Electronic Devices Based on Solution-Processed Graphene Composites and Inkjet Printing
Authors: Chin Byung Doo , Jo Sung Min 
Published: February 2020

A facile and cost-effective strategy for foldable and flexible electronics is solution process, such as inkjet printing, of graphene-based materials, which will be also useful for application with large area or ultra-thin form factor. In this presentation, graphene ink and graphene/silver nanowire (AgNW) paste were formulated and printed on the surface-treated flexible/foldable substrates, including plastic or functionalized paper. Circuits of the graphene nano-plates, prepared on the paper substrate by simple transfer printing, showed a very small change in the conductance under various folding angles, retaining more than 90% of initial conductance after repeated cycles [1]. Moreover, compared with electrodes formed by neat graphene, graphene/AgNW circuit showed superior performance both for sheet resistivity as well as folding stability. For the inside (−180◦) and outside (+180◦) folding angle condition, the circuits revealed much smaller change in conductance, maintaining the electronic path on foldable paper.
Due to the lack of transparency for most paper-based substrate, top-emitting organic light emitting diode (TOLED) was employed, where its light emitting behavior and efficiency were investigated in terms of the multilayer surface composition on paper and functionality. TOLED on paper was prepared by thermal evaporation or printing of several organic layers onto the reflective anode, where the interconnecting graphene/AgNW circuit supplied the bias voltage and current. Electrical and luminous properties of TOLED were dependent upon the applied bias voltage driven by graphene/AgNW electrodes [2].
Solution-phase direct exfoliation of neat graphene is favorable for maintain higher conductivity of printed patterns [3]. We have dispersed graphene nano-platelets in methanol, with 0.5wt% polymeric surfactant (such as triton X-100). Improved uniformity and printability of graphene-based ink materials and their patterns were evaluated using the commercial inkjet/simple nozzle printing. Tiny droplets of graphene or graphene-AgNW composite solution ink could be jetted onto a fast-moving substrate to produce 100μm-width pristine line patterns. Pattern uniformity and resolution were further controllable by the adjusting of the surface tension via ink formulation as well as modification of functional surface of paper substrates. Organic thin film transistor with various patterns/channel length of graphene-base electrodes were fabricated for the evaluation of printed graphene circuits.

References

[1] W. J. Hyun, O O. Park, B. D. Chin, Adv. Mater., 2013, 25, 4729-4734
[2] S.M. Jo, D. G. Yoon, R. Bail, B. D. Chin, ECS J. Sol. Sta. Sci. and Tech.
2016, 5, R3185-R3190
[3] E. B. Secor, P. L. Prabhumirashi, K. Puntambekar, M. L. Geier, M. C. Hersam, J. Phys. Chem. Lett.
2013, 4, 1347-1351
Reduction of Europium Ions in SrAl2O4 Glass Composites Using Aluminum Nitride
Authors: Nakanishi Takayuki , Fushimi Koji , Hasegawa Yasuchika 
Published: February 2020

Frozen sorbet technique has applied to the SrO-Al2O3-B2O3 glass system to prepare glass composites including Eu2+, Dy3+:SrAl2O4 (SA) microcrystals1. The glass composites show remarkable light-storage ability based on the natural properties of divalent europium in SA crystals, and this provide various photo-functionalities, such as long-persistent luminescence, photo-induced conductivity, and mechano-luminescence. Their unique optical properties of SA glass composites are expected to become novel light-storage materials for future energy applications.
To control the valence states of europium (Eu3+ or Eu2+) is one of the important factors for the development of photo-functional glasses2. Generally, industrially mass-produced glasses have been prepared by melting raw materials at high temperature in air (oxidizing atmosphere), and then the valence of multivalent ions is determined by redox equilibrium in glass melt. For some special applications, photo-functional glasses have been prepared under reduction atmosphere using H2 or CO gas to design low valence state of ions or metal formation in glasses. Low valance lanthanide ions, such as Eu2+, Yb2+, Sm2+, and Ce3+, for example, have been used as functional centers for laser materials, phosphors, and magnetic-optical memory devices. Considering the difficulty and safety in H2 or CO gases use, more convenient and simple glass preparation methods are strongly required.
Here, a new method for the reduction of Eu3+ to Eu2+ in SrO-B2O3-Al2O3-Eu2O3 (-AlN; reducing agent) system was proposed using a Frozen sorbet technique in air. Effective reduction of Eu3+ in SA crystals during the melting at 1500oC was demonstrated using differential thermal analysis (DTA), thermogravimetric analysis (TGA), and the optical properties. The reduction of Eu3+ to Eu2+ in AlN added glasses was proposed to proceed by the reaction of 2AlN + Eu2O3 + O2 (in air) → Al2O3 + 2EuO + N2. In this study, we have attempted to prepare the SA glass composites under various conditions using reducing agent; AlN for the frozen sorbet technique. Highly transparent SA glass ceramics were successfully synthesized and characterized using X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) with energy-dispersive X-ray analysis (EDX). The emission spectra and lifetime decays were observed using a steady-state and time-resolved spectrofluorophotometer system. Light-storage glass ceramics using the frozen sorbet method under oxidation control overcomes the limitation of Eu activated materials and the results of this study should be a significant contribution to the fields of inorganic chemistry and material design.
References

1. T. Nakanishi, Y. Katayama, J. Ueda, T. Honma, S. Tanabe, T. Komatsu, J. Ceram. Soc. Jpn., 119, 609 (2011).
2. T. Nakanishi, K. Watanabe, J. Ueda, K. Fushimi, S. Tanabe, Y. Hasegawa, J. Am. Ceram. Soc., 98, 423 (2015).
Scintillation Properties of Ga2O3 Crystal
Authors: Yanagida Takayuki , Okada Go , Kawaguchi Noriaki , Yanagida Satoko 
Published: February 2020

Ionizing radiation detectors are used in many kinds of non-destructive investigations. Many of such applications use a scintillation detector which consists of scintillator and photodetector. A scintillator is a type of the luminescent material that converts a high energy ionizing radiation photon/particle to hundreds of visible photons via energy migration from the host matrix to emission centers. Scintillators have been playing an important role in many scientific and industrial fields, including astrophysics, particle physics, medical imaging, security, nuclear plants, and well-logging. Although insulator materials doped with rare-earth or transition metal ions are commonly used in practical applications, semiconductor crystals have also attracted attentions due to their intrinsically high light yield and fast decay time without doping of any emission centers.
In this work, optical and scintillation properties of well-known Ga2O3 semiconductor material are investigated. Under UV excitation, photoluminescence (PL) emission peak appeared around 380 nm with the quantum yield of 6%, and fast decay of 8 and 793 ns were observed. In contrast, X-ray induced scintillation spectrum also showed an intense emission band around 380 nm, which of decay curve was reproduced by two exponential decay components with the time constants of 8 and 977 ns. The pulse height spectrum of 137Cs g-rays measured using measured Ga2O3 showed a clear photoabsorption peak with a light yield of 15000 ± 1500 ph/MeV. This high light yield was the highest value among the semiconductor scintillators reported.
High Electroluminescence of ZnS:Cu Phosphor with a CNT-Incorporated Dielectric Layer
Authors: Yu SeGi 
Published: February 2020

High brightness was obtained for alternating current-driven inorganic ZnS:Cu powder electroluminescence (EL) devices by incorporating carbon nanotubes in a barium titanate (BaTiO3) based dielectric layer. The inorganic EL devices were consisted of four layers: a top electrode, a dielectric layer, an emitting layer, and an ITO layer which was pre-coated on the glass substrate. As an emitting material, ZnS:Cu power of particle size 9 µm (green emission) was mixed with the cyanoethyl pullulan polymer (CEP), as an organic binder, and the dimethyl formamide (DMF) organic solvent. The emitting solution was spin-coated on the ITO glass at the fixed speed of 1200 rpm. The BaTiO3 power were mixed with a CNT-CEP binder, which was also spin-coated on the emitting layer. In order to optimize the EL performance, the concentration of CNTs were varied by controlling the mixing ratio of CNTs—0, 0.0018, 0.0039, 0.0071, 0.011 and 0.014 wt%. Finally, a 500-nm-thick aluminum top electrode was thermally evaporated onto the dielectric layer. Up to 50% higher brightness was obtained for the CNT concentration of 0.011 wt%. The high brightness might be caused by the high dielectric constant of the CNT-incorporated BaTiO3 dielectric layer, thanks to the micro-capacitor effect. [Z. M. Dang et al., Small 12, 1688 (2016).] Roughly speaking, the higher concentration of the CNT yielded to the higher brightness, until a certain concentration, here, between 0.011 and 0.014 wt%. It implies that too high concentration of CNTs might lead to the formation of the unwanted percolation network of a leakage current within the dielectric layer. Finally, the role of the chlorine was investigated by inclusion of chlorobenzene into the CNT-containing dielectric layer. [J.-Y. Kim et al., Adv. Mater. 25, 2308 (2013).] Based on the above results, incorporation of CNTs within the dielectric layer enhanced the brightness (and the efficiency, possibly) of the ZnS:Cu-based EL device, which would help to extend the potential applications of EL devices.
X-Ray Excited Luminescence of Terbium Doped Sodium Aluminium Phosphate Glass
Authors: Kawaguchi Noriaki , Kuro Tomoaki , Okada Go , Yanagida Takayuki 
Published: February 2020

Luminescent materials which convert high energy photons to visible light are used for medical X-ray radiography. These materials contain luminescent centers with high efficiency, for example trivalent Tb ions in oxysulfide gadolinium ceramic. Generally, luminescent materials for X-ray radiography exhibit slower decay times than scintillators for photon-counting applications, however they also exhibit low afterglow.
In this study, we researched about X-ray excited luminescence characteristics of sodium aluminium phosphate glass which is lower melting point than oxysulfide gadolinium ceramic. Tb doping concentrations of sodium aluminium phosphate samples were 0.3, 1.0, 3.0 and 10%, respectively. As a result of X-ray excited luminescence, emission peaks at wavelengths of around 480, 540, 580 and 620 nm were observed from each samples. Intensity of X-ray excited luminescence were increased with increasing of Tb doping concentration. Decay curves of samples were also evaluated by using X-ray induced afterglow characterization system [1] which was developed by our laboratory. Slow decay curves with time range of 20 milliseconds were successfully observed.

[1] T. Yanagida, Y. Fujimoto, T. Ito, K. Uchiyama, K. Mori, "Development of X-ray induced afterglow characterization system" Appl. Phys. Exp., 7 062401 (2014).
(Invited) Polymeric Materials in LEDs: Outlook and Challenges
Authors: Piquette Alan , Tchoul Maxim , Linkov Alexander 
Published: February 2020

In traditional lighting technologies, such as discharge and incandescent lamps, polymers were unsuitable materials because of the high temperatures and/or ultraviolet light. In solid state lighting (SSL), however, polymers and polymer-based composites are ubiquitous. They are used in housing materials, adhesives, encapsulants, lenses, flexible substrates, light-weight heat sinks, and in various other applications. Virtually all SSL products have some form of polymer present in their make-up. In this presentation, we will discuss the use of polymers in LED-based lighting, highlighting the challenges and outlook. The primary focus will be on their applications as encapsulants and adhesives.
The most abundantly used technology in producing white light with LEDs is based on phosphor conversion. It has been estimated that >75% of the white LED market relies on phosphor conversion.[1] Whether the phosphor is present as a powder, polycrystalline ceramic, single crystal, or thin-film, polymers are often used to either glue the conversion layer to the LED chip, encapsulate the phosphor particles, or both. For these applications, optical silicones are the usual choice. Even though silicones have many desirable properties, there are three main challenges that limit their performance as adhesives or encapsulants: (i) low thermal conductivity, (ii) low refractive index, and (iii) long term photo-thermal stability. The Department of Energy (DOE) SSL R&D Plan lists LED encapsulation as a key issue and R&D priority.[2]

In this talk, we will briefly present the history of polymer encapsulants for LEDs, leading up to the use of state-of-the-art optical silicones. We will discuss the associated limitations of these materials in terms of losses and how LED performance could improve with advancements in polymer and polymer-composite technology.
References:
[1] Company estimates based on McKinsey & Company, Lighting the Way: Perspectives on the Global Lighting Market, 1st ed. (2011).
[2] DOE SSL Program, "R&D Plan," prepared by Bardsley Consulting, SB Consulting, SSLS, Inc., LED Lighting Advisors, and Navigant Consulting, Inc., May 2015; http://energy.gov/eere/ssl/downloads/solid-state-lighting-rd-plan.
Printing of Enzyme Electrodes on Nonwoven Fabric for Flexible Biofuel Cells
Authors: Hsieh Yunchen , Ogawa Yudai , Kato Yuto , Kai Hiroyuki , Nishizawa Matsuhiko 
Published: February 2020

Enzymatic biofuel cells (EBFCs) are lightweight and eco-friendly power sources that employ enzymes as catalysts and sugar as fuel for redox reactions at ambient temperatures. Due to their lightness and biocompatibility, EBFCs recently attract a great deal of attention and have been applied to a wide range of medical, implantable, and wearable devices [1-5]. We previously developed an iontophoresis skin patch with a built-in EBFC for enhancing drug delivery through skin by ionic current generated by the EBFC. The electrodes of the EBFC in the skin patch were made by multi-step fabrication. Carbon fabric was immersed in the dispersion of carbon nanotubes (CNTs) to make electrodes, followed by immobilization of enzymes onto them. Fructose dehydrogenase (FDH) was immobilized on an anode, and bilirubin oxidase (BOD) on a cathode to form a complete EBFC. In this study, we developed ink of CNTs and enzyme that can be printed onto nonwoven fabric that works as a flexible substrate. This material simplifies the fabrication process of CNT/enzyme electrodes, and enables patterning of the electrode with an arbitrary shape.
To prepare the CNT/enzyme ink, CNT and additives of different roles were first mixed in aqueous solution and dispersed by sonication: CNTs as a highly-conductive scaffold for enzyme immobilization, polyvinylimidazole (PVI) as a binder, trehalose as a stabilizer of enzymes during freeze-drying, and 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBSE) for non-covalent immobilization of enzymes to CNTs. Next, FDH as an enzyme catalyst for an anode was added to the mixture above to complete the CNT/enzyme ink. The CNT/enzyme ink was cast on nonwoven fabric in 1 cm2 size to form an anode. Finally, the cast electrode was freeze-dried for 6 hours. After freeze-drying, the fabricated FDH anode had highly porous structures as observed by scanning electron microscopy, and it could be preserved for longer time after freeze-drying because of trehalose.
The performance of the printed FDH anode and the effects of the additives were evaluated. The FDH anode was immersed in a stirred buffer solution containing 200 mM fructose and measured by typical cyclic voltammetry (CV) at 10 mV/s. The FDH anode generated current density of 2 mA cm-2 with fructose as fuel. Though the printed ink was originally aqueous dispersion, the printed shape was kept intact after rehydration, while without PVI the printed electrode readily dissolved in buffer solution. CV of the anode in the presence and absence of PBSE indicated that PBSE was essential for high power density.
[1] Enzymatic Fuel Cells from Fundamental to Applications (Eds: H. R. L uckarift, P. Atanassov, G. R. Johnson), Wiley, New Jersey, 2014
[2] W. Gellett, et al., Electroanalysis.,
22, 727, (2010)
[3] G. Valdés-Ramírez, et al., Electrochem. Commun., 47, 58, (2014)
[4] S. Cosnier, et al., Electrochem. Commun., 38, 19, (2014)
[5] Y. Ogawa, et al., Adv. Healthc. Mater., 4, 506, (2015)

Figure 1
High-Energy Density Metal-Free Biobatteries Powered By Soft Drinks
Authors: Zhu Zhiguang , Zhang Y-H Percival 
Published: February 2020

More and more portable electronics urgently require better batteries featuring high-energy density, good safety, and low environmental impacts. Enzymatic fuel cells are a promising micro-power source for small electronics. However, incomplete oxidation of sugars mediated by few redox enzymes and low faraday efficiency result in low energy storage densities. Here we demonstrate the complete oxidization of sucrose, glucose, and fructose at the anodic compartment of biobatteries via a synthetic 15-enzyme pathway. The biobatteries generated maximum power densities from 0.65 to 0.98 mW cm-2. Also, a nitrogen-doped activated carbon cloth was used as a flexible cathode to achieve oxygen reduction reaction faster than that catalyzed by platinum-coated membrane electrode assembly. Biobatteries comprised of 15 enzymes oxidize sucrose, fructose and glucose simultaneously, generated nearly 24 electrons per hexose with faraday efficiencies of approximately 95%. Metal-free biobatteries powered by commercial soft drinks whose energy-storage density was ~400 Ah kg-1 of drinks exhibited maximum power densities of up to 0.55 mW cm-2, implying that soft drinks could be perfect fuels for bioelectricity generation.
Electrochemical and Power Performance of Microbial Fuel Cells: A Novel Numerical Approach
Authors: Falcucci Giacomo , Nastro Rosa Anna , Cigolotti Viviana , Minutillo Mariagiovanna , Jannelli Elio 
Published: February 2020

In this work, a novel numerical approach for the simulation of electrochemical and power performance of Microbial Fuel Cells (LBM) for waste-water treatment is proposed.
Our model is based on the accurate description of the MFC internal phenomena by means of the Lattice Boltzmann Method, a numerical approach based on an optimized formulation of Boltzmann's Kinetic Energy, which has been successfully applied to phenomena of technical and engineering interest in recent years.
Employing a multi-component LBM solver, an accurate prediction of wastewater flow through the reactor chamber is achieved; within the LBM framework, a novel methodology has been developed to account for the different types of anode materials in MFC reactors (carbon fiber brushes or solid porous media). The direct conversion of organic substrate into e
- and H
+ through microbs metabolism has been modeled according to dedicated experimental activity. The electrochemical characteristics of anode and cathode electrodes have been included and their effects on internal species transport and charge transfer is accurately simulated.
The very good agreement between our results and the experiments in literature highlight the reliability and versatility of LBM applied to MFC implementations.

Figure 1
The Unusual Redox Properties of Fluoroferrocenes Revealed through a Comprehensive Study of the Haloferrocenes
Authors: Inkpen Michael , Du Shuoren , Hildebrand Mariana , White Andrew , Harrison Nicholas , Albrecht Tim , Long Nicholas , Long Nicholas 
Published: February 2020

We report the synthesis and full characterization of the entire
haloferrocene (FcX) and 1,1′-dihaloferrocene (fcX2) series (X = I, Br, Cl, F; Fc =
ferrocenyl, fc = ferrocene-1,1′-diyl). Finalization of this simple, yet intriguing set of
compounds has been delayed by synthetic challenges associated with the incorporation of
fluorine substituents. Successful preparation of fluoroferrocene (FcF) and 1,1′-
difluoroferrocene (fcF2) were ultimately achieved using reactions between the
appropriate lithiated ferrocene species and N-fluorobenzenesulfonimide (NFSI). The
crude reaction products, in addition to those resulting from analogous preparations of
chloroferrocene (FcCl) and 1,1′-dichloroferrocene (fcCl2), were utilized as model
systems to probe the limits of a previously reported “oxidative purification” methodology. From this investigation and careful solution voltammetry studies, we find that the fluorinated derivatives exhibit the lowest redox potentials of each of the FcX and fcX2 series. This counterintuitive result is discussed with reference to the spectroscopic, structural, and first-principles calculations of these and related materials.
Ionic Liquid|Water Interface As an Electrochemical Reaction Field for the Formation of Novel Metal Nanostructure
Authors: Nishi Naoya 
Published: February 2020

Electrochemistry at interface between two immiscible electrolyte solutions (ITIES) has been explored in the novel liquid-liquid two-phase system of water (W) and ionic liquids (ILs) since more than a decade ago [1,2]. One of several characteristics of ILs is the ability to disperse and stabilize metal nanostructures in ILs without addition of any capping reagents, which seems to result from the existence of ionic multilayers [3,4], a rigid interfacial structure, formed on the metal surface. This characteristic motivated us to study electrochemical deposition of metal at the IL|W interface utilizing electron transfer across the interface.
When we used AuCl4
- as the metal source dissolved in W and a reducing reagent dissolved in trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide, which is a highly hydrophobic IL, spontaneous and simultaneous electron transfer-ion transfer reaction occurred and dendritic Au nanofibers were formed at the interface [5]. Similar dendritic nanofibers were formed at the IL|W interface of other highly hydrophobic ILs, although the fiber diameter depended on the ionic species of the ILs. On the other hand, when we used a conventional organic solvent, dichloromethane, instead of ILs, we obtained not nanofibers but micro-scale burr-like structures. In the present paper, the mechanism of the formation of such highly anisotropic nanostructure will be discussed and the application of this system to other nanostructures such as metal-polymer composites will be introduced.
[1] T. Kakiuchi and N. Nishi, Electrochemistry, 74 (2006) 942-948.
[2] Z. Samec, J. Langmaier, T. Kakiuchi, Pure Appl. Chem., 81 (2009) 1473-1488.
[3] N. Nishi, Y. Yasui, T. Uruga, H. Tanida, T. Yamada, S. Nakayama, H. Matsuoka, T. Kakiuchi, J. Chem. Phys., 132 (2010) 164705(1-6).
[4] N. Nishi, T. Uruga, H. Tanida, J. Electroanal. Chem., 759 (2015) 129-136.
[5] N. Nishi, T. Kakinami, T. Sakka, Chem. Commun., 51 (2015) 13638-13641.