bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanotechnology for Water-Less Cleaning of Solar Panels†
Authors: Das Sanjana , Silic Stephanie , Das Biswajit 
Published: February 2020

Clean energy technologies are the present focus for fulfilling the rising demand for energy across the globe. Whereas vast majorities of researchers are working on increasing the efficiency, far less investment and research have been done in addressing the externalities that can be a setback for the technology deployment.
One of the very important externalities among them is dust and airborne sedimentation on the solar panels over time. In order to clean the dust off the solar panels, most Photo Voltaic (PV) installations perform periodic water cleaning. However, as locations with higher annual solar flux are usually arid, there is a strong demand for water-less cleaning of solar panels. While some water-less cleaning technologies currently exist, primarily based on NASA’s lunar and mars expeditions, most of these techniques are expensive and not cost effective for large-scale PV power generation.
We are currently using nanotechnology to develop a process for the water-free cleaning of solar panels, which we believe will be cost-effective for large scale PV generation. The technology involves the use of arrays of transparent nanoparticles deposited on the solar panels using a low cost technique. The nanostructure arrays provide focused electric field to modify the electrical properties of the dust particles; the charged dust particles are then removed by electrostatic sweeping.
† This work is supported by the National Science Foundation under Grant No. IIA-1301726
Copper Nanowire Array Electrodes with Electropolymerized Polyaniline Corrosion Barrier
Authors: Moncada Jorge , Carrero Carlos , Oh Tae-Sik 
Published: February 2020

High surface area electrodes are essential for the performance of electrochemical devices for energy storage and water treatment. Carbon-based materials, mostly carbon aerogels and activated carbon, have been the usual choice for supercapacitors and capacitive deionization systems while organic-inorganic composite electrodes, featuring dispersed oxide particles on organic backbone in most cases, are currently getting attention for their distinct electrosorption properties. To expand the materials boundary even further to metallic nanowire arrays, it is necessary to develop a corrosion protection scheme that is compatible with the structural complexity of the electrode. To this end, we investigated electropolymerization route to form conformal polymeric corrosion protection barrier on a high surface area electrode based on copper nanowire array. We started from polyaniline since its electropolymerization process has been applied for smooth copper substrate [1]. Copper foils were heat treated in air to grow an intermediate array of copper oxide nanowires. After reducing copper oxide nanowires to copper nanowires preserving the high surface area [2], various polymer coatings were electrochemically grown on the surface of the copper nanowires [3]. We confirm the corrosion protection performance of the polymer coatings in an acidic environment by cyclic voltammetry and electrochemical impedance spectroscopy. The correlation between electropolymerization parameters and copper nanowire corrosion kinetics is discussed.
[1] Berrin Duran, Metehan C. Turhan, Gözen Bereket, A. Sezai Sarac, Electrochim. Acta, 55, 104 (2009).
[2] Evan C. Brown, Ph.D. thesis, Caltech, 2011.
[3] J. Heinze, Synthetic Met., 41-43, 2805 (1991).
Physical SPICE Model of Organic Thin Film Transistor
Authors: Bonnassieux Yvan , Jung Sungyeop , Horowitz Gilles 
Published: February 2020

Electronic devices operate through charge carrier injection and transport, which are strongly dependent to the electronic structure of the semiconductor. For disordered organic semiconductors, Gaussian density-of-states (Gaussian DOS) and hopping transport are often proposed, described by analytical expressions for the charge carrier mobility as a function of the charge carrier density, electric field and temperature. However, due to the mathematical complexity of this approach, device level modelling is still lacking. In particular, for OFETs, correlation between charge carrier mobility and field-effect mobility is not sufficiently understood.
We proposed an analytical model, easy adaptable to spice model, for the linear regime transfer characteristics of OFETs with power-law dependent μ and RC. The ratio method provides a set of parameters that give good match between transfer characteristics from experiment and model.
This work has been funded by Horizon 2020 Marie Skłodowska-Curie Research and Innovation Staff Exchange (RISE) Program (2015–2019) entitled DOMINO.
Mapping Changes Induced By Few Monolayers of Al2O3 on a CuO Nanowire Surface
Authors: Banerjee Sriya , Gao Zhengning , Myung Yoon , Banerjee Parag 
Published: February 2020

Thermal oxidation of copper leads to the spontaneous growth of single crystalline and pristine CuO nanowires which is an attractive materials platform for photoelectrochemical and photochemical applications. However, our limited understanding of CuO nanowire surfaces remains a bottleneck for its widespread adaptation as a material for energy conversion. One approach to probe the CuO nanowire surface is to investigate changes to its chemical and electrical signature upon deposition of a few monolayers (< 2 nm) of Al2O3; a chemically and electrically passivating film. Exactly how Al2O3 might achieve this passivity is the subject of this talk.
We progressively map, ex situ
, the effect of adding few monolayers of Al2O3 on the surface chemistry and electrical characteristics of a single CuO nanowire. The CuO nanowire is contacted electrically via electron beam lithography (Figure 1a), prior to the deposition experiments. Using atomic layer deposition (ALD), Al2O3 is deposited using trimethyl aluminum (TMA) and H2O as reactants. A deposition rate of 1Å/cycle is obtained. The chemical changes on the nanowire surface are studied by X-ray photoelectron spectroscopy (XPS) and electrical properties of the nanowire are recorded after every monolayer deposition.
XPS fine spectra of Cu 2p reveal a clear reduction of Cu2+ to Cu1+ after only a single pulse of TMA. The O 1s fine spectra reveals the formation of Al-O and Cu+1-O bonds and removal of adsorbed O species after 1 cycle of Al2O3
(Figure 1b). The Al 2p fine spectra shows a clear Al-O bond formation after ~ 3 cycles of ALD. Thus, a clear surface reduction of CuO nanowire and subsequent formation of Al2O3 is noted in XPS studies. This change in surface chemistry manifests itself in the electrical characteristics as a detectable photocurrent response under ambient (760 Torr) conditions; where, for a pristine CuO nanowire, no such response is previously observed (Figure 1c). Current-voltage characteristics are mapped as a function of temperature and discussed in light of the changes to surface properties observed via XPS.

Figure 1
Frequency and Area Dependence of High-K/Ge Mos Capacitors
Authors: Mitevski Ivan , Ding Yiming , Misra Durga 
Published: February 2020

Abstract

– Ge substrate devices in Complementary Metal Oxide Semiconductors (CMOS) technology have been extensively studied due to its high electron and hole mobility [1]. However, most of the Ge devices have some limitation as making a high-quality Ge/High-k gate stack is rather difficult compared to Si/High-k system. The purpose of this work is to further study the capacitance measurements of a MOS capacitor at different frequencies for square devices with different side lengths (10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 100 μm). The series resistance corrected capacitance (Cc) for accumulation region increases on a faster pace when a lower frequency (1KHz) is used than at a higher frequency (1MHz) (Figure 1(a)) as a function of side length, a. Accumulation capacitance has a strong dependence on frequency in metal oxide semiconductor devices. Our devices follow the same trend as previous studies have reported [2]. On the other hand, our study shows substantial decrease of Cc per unit area in Ge/High-K in comparison to High-K/Si devices (Figure 1(b)). This decrease is attributed to the large non-uniform interface defect density [3], high leakage current [3] associated with Ge stacks and fringing field effect [4]. Capacitance at accumulation condition depends on interface capacitance (Cit) which changes with defects density. Defect density increases proportionally with area and High-K/Ge devices, being leakier, experience a higher decrease of Cc per unit area than High-K/Si devices. The impact of fringing field capacitance (CL) on parallel plate capacitance (CP) decreases when device area is increased (Figure 1(c)) and this contributes to further decrease in total capacitance Cc per unit area. This work explains the frequency dispersion of high-k MOS capacitance in accumulation region and the unit capacitance decrease when Ge substrate is used. The study also models the fringing field capacitance [5] and its effect on MOS devices.

Figure 1 (a) Corrected capacitance (C
c) measured at -1.5 V (accumulation) at 1 MHz and 1 KHz shows frequency dependence; (b) Unit Capacitance is plotted against area for Ge substrate and Si substrate sample for measurements at frequency of 1MHz. C
s is substrate capacitance and C
ox is oxide capacitance; (c) CL/CP as a function of area. CL and CP are calculated as per Yuan & Trick’s model [5].
[1] D. Kuzum, A. J. Pethe, T. K., K. C. S, IEEE T. Electron. Dev., vol. 56, p. 648, 2009.
[2] P. R. Lee, J. R. Ruzyllo, Electrochemical Society, vol. 9, p.353-362, 2007.
[3] Y. M. Ding, D. Misra, J. Vac. Sci. Technol. B, vol. 34, p. 021203 2016.
[4] S. Maurya, B. R. Singh, Solid States Physics, AIP Conf. Proc. 1512, 742-743, 2013.
[5] E. Barke, IEEE Transactions on Computer Aided Design, vol. 7, No. 2, 1988.

Figure 1
Preparation of Cu2znsn(S
x
Se1-x
)4 (CZTSSe) Single-Phase Sputtering Target By Sintering Binary Alloy Powders and Its Applications to Cztsse Thin-Film Solar Cell
Authors: Lee Meng-Huan , Lin Yu-Pin , Hsieh Tsung-Eong 
Published: February 2020

Cu(In,Ga)Se2 (CIGS) is the main photo-absorption layer of thin-film solar cells; however, relative scarcity of In and Ga elements and the selenization using toxic H2Se gas inhibit its practical usage. Cu2ZnSnS4 (CZTS) becomes the promising alternative due to its similar physical properties to CIGS, abundance of Zn and Sn elements in earth and low toxic preparation method. Moreover, the bandgap of CZTS can be modulated by adding selenium (Se) to form the CZTSSe so as to improve the performance of photovoltaic (PV) devices.
This work adopts the CuSe, ZnS and SnS2 binary alloy powders as the starting ingredients to prepare thesingle-phase CZTSSe sputtering target. The powders were mixed at the molar ratio of Cu:Zn:Sn = 1.6:1:1, pressured into the pellets form with 6 mm in diameter, sintered in the N2 ambient at temperatures ranging from 200 to 600°C for 8 hrs. The microstructures and phase constitutions of pellets subjected to various sintering treatments were then characterized in order to identify the sintering condition that may yield the single-phase CZTSSe structure.
The phase evolution in pellets characterized by x-ray diffraction (XRD) revealed that the single-phase kesterite CZTSSe structure can be obtained by the sintering at 600°C and the energy dispersive spectroscopy (EDS) indicated its stoichiometric ratio is Cu26.18Zn13.73Sn12.02S35.22Se11.86 which is close to the ideal ratio of 2:1:1:4.
The 2-inch CZTSSe sputtering target was then prepared for CZTSSe layer deposition in accord with the optimized sintering condition. XRD and Raman spectroscopy analyses revealed the deposited CZTSSe layer subjected to the post annealing at 570°C for 1 hr in N2 ambient also possesses the single-phase kesterite structure. EDS analysis found its stoichiometric ratio is Cu24.50Zn14.02Sn13.92S38.20Se9.36 which are close to the ideal ratio of 2:1:1:4 with the Cu-poor/Zn-rich feature. Presently, the CZTSSe layers with desired grain morphologies and compositions are transferred to the preparation of thin-film solar cell and its PV performance is evaluated.
Tuning the Carbon Crystallinity for Highly Stable Li-O2 Batteries
Authors: Bae Youngjoon , Yun Young Soo , Lim Hee-Dae , Park Hyeokjun , Lee Hongkyung , Kim Yun-Jung , Kwon Hyuk Jae , Kim Hyunjin , Kim Hee-Tak , Im Dongmin , Kang Kisuk 
Published: February 2020

The increasing demands for emerging high-energy-density applications, such as electric vehicles, have prompted considerable efforts to design a new type of innovative, sustainable battery. Li–O2 batteries can deliver much higher energy densities than current Li-ion batteries and have thus attracted much attention; however, their poor cyclic stability remains a major obstacle to their use in high-energy-density applications. The carbon-based cathode materials (CCMs) used for Li–O2 batteries are considered one of the origins of this cycle-life degradation, which has led to the development of several alternative types of cathode materials, such as Au or TiC.1,2,3 However, there is currently no practical substitute for CCMs, which exhibit desirable properties such as high specific surface area, high electrical conductivity, light weight, and chemical stability and involve the use of well-known technologies with low processing and raw material costs. This study provides a new perspective on Li–O2 batteries, for which the cyclic stability can be dramatically increased using well-ordered graphitic CCMs. Through a systematic investigation on the controlled carbon, we demonstrate that the graphitic crystallinity of carbon is an important factor in determining the stability of not only the cathode but also the electrolyte. To discern the degradation factors affecting the cathode from those affecting the electrolyte, we used carbon isotope (13C)-based air electrodes with various degrees of graphitic crystallinity. Furthermore, in situ differential electrochemical mass spectroscopy analysis clearly demonstrates that as the crystallinity of the carbon increases, the CO2 evolution from the cell is reduced, which leads to a three-fold enhancement in the cycle stability of the cell.

Reference

1. Thotiyl, M. M. O. et al.,
J. Am. Chem. Soc.
2012, 135, 494
2. Peng, Z et al., Science
2012, 337, 563
3. Thotiyl, M. M. O. et al., Nat. Mater.
2013, 12, 1050
Passivation Layer of Magnesium-Based Negative Electrodes
Authors: Matsui Masaki , Kuwata Hiroko , Yamauchi Masatsugu , Imanishi Nobuyuki 
Published: February 2020

Rechargeable magnesium batteries are getting more interests as a potential beyond Li-ion chemistry in the battery field. Of course a lot of the challenges of the rechargeable magnesium batteries are remaining for cathodes, anodes and electrolytes. In the case of the anode active materials, since formation of the passivation layer at the surface of the magnesium metal is the most critical problem for the reversible deposition and dissolution process, halide based electroltye solutions are preferred. On the other hand, the halide-based electrolyte sotluion always has voltage limitation due to the corrosion of the current collector. As a consequence, it is very challenging to develop a high voltage magnesium batteries.
Previously we reported that the magnesium metal can be easily passivated in the Mg(TFSA)2 BuMe-triglyme solution using XPS and in situ FTIR. It is mainly due to the electrochemical reduction of the TFSA anion to form the passivation layer resulting in the high overpotential. However, a magnesium-based intermetallic compound: Mg3Bi2 showed good reversibility in the Mg(TFSA)2 BuMe-tryglyme solution with very low overpotential. Even though the decomposition of the TFSA anion itself was still observed by XPS, the surface layer formed on the Mg3Bi2 could not be enough stable to work as the passivation layer.
In the present study, we synthesized various magnesium-based intermetallic compounds such as Mg3Bi2, Ma3Sb2 and Mg2Sn via solid-state process and investigated the stability of the passivation layer formed at the surface of the intermetallic compounds. In the ambient atmosphere, Mg3Bi2 and Mg2Sn were easily decomposed to form Bi and Sn respectively. On the other hand, the Mg3Sb2 was extremely stable even with water. These results well matches with the electrochemical performances of the each intermetallic compounds. The obtaind results suggest that the formation of the alloy or intermetallic compounds de-stabilizes the surface of the magnesium. We think the destabilization of the magnesium improves the performance of the anode active materials.
Intermetallic Li-Anode Alloys Based on Cu, Sb and Sn
Authors: Beutl Alexander , Fuertauer Siegfried , Berger Patric , Li Dajian , Cupid Damian Marlon , Flandorfer Hans 
Published: February 2020

Intermetallic alloys are promising candidates for new anode materials for lithium ion batteries (LIBs) in high energy applications because of the significantly increased theoretic capacities when compared to conventionally used graphite. However, the drastic volume changes during lithiation of pure metals such as Si or Sn lead to degradation of the electrode material resulting in very high capacity fading and low cycling stability. One of the various concepts to solve this problem is to use intermetallic alloys instead of pure metals. For example, Cu6Sn5, Cu3Sn and Cu2Sb are promising anode materials because Cu does not form intermetallic compounds with Li. A (Cu)-alloy matrix which precipitates during lithiation would act to buffer the strain induced by volume changes and simultaneously ensures electrical contact between lithiated phases. A similar effect can be observed using SbSn as anode material. In this case Sn acts as a buffer because Li-Sb alloys are preferably formed by lithiation.
Advanced materials design and engineering based on computational methods rely significantly on experimentally determined thermodynamic and phase diagram data of the material systems. These data are used as inputs to model the Gibbs free energies of all phases, thereby generating self-consistent thermodynamic descriptions of the multi-component systems. These can in turn be used to predict lithiation pathways and simulate the electrochemical behaviour of half cells with different active material compositions. Furthermore, knowledge of phases and their crystal structures is crucial for kinetic studies of lithiation processes. From our comprehensive experimental data, including powder X-ray diffraction, single crystal X-ray diffraction, thermal analysis, and coulometric titration, we obtained self-consistent CALPHAD descriptions.This presentation will give an overview of our experimental procedures and the results of our work on the materials systems Cu-Li-Sn, Cu-Li-Sb and Li-Sb-Sn.
This work has been funded by the FWF under the project I559-N19 and by the DFG under the projects FL-730/1-2 and CU 203/ 1-2, all within the DFG priority project SPP 1473 “WeNDeLIB”.
Iron Oxide Nanosheets As High Performance Cathodes for Lithium-Ion and Sodium-Ion Batteries
Authors: Niu Sibo , Godinez-Salomon Fernando , Rhodes Christopher 
Published: February 2020

Cathodes with high lithium-ion and sodium-ion capacities, the ability to be rapidly charged and discharged, and that are extremely low-cost are needed for numerous applications including electric vehicles, consumer devices, and grid-level energy storage. Iron oxides are of significant interest based on their low cost, low toxicity, and high natural abundance, however iron oxide cathodes typically have low specific capacities and very poor rate capabilities. Our work has shown that synthesizing and stabilizing iron oxide in a nanosheet architecture results in significantly improved lithium-ion charge storage capacities compared to iron oxide nanoparticles at both slow and fast charging/discharging times. The iron oxide nanosheets were determined to have lateral dimensions of ~50 nm, thicknesses of ~1 nm, and be composed of smaller crystallites. From X-ray diffraction, Raman spectroscopy, and high resolution microscopy, the structure of the nanosheets was consistent with maghemite, γ-Fe2O3. The γ-Fe2O3 nanosheets exhibit significantly better electrochemical properties with higher capacities and rate capabilities (110 mAh/g at ~3C) compared with comparable iron oxide nanoparticles. The improved electrochemical performance of γ-Fe2O3 nanosheets has been demonstrated to be related to multiple factors including high surface area, a predominantly surface charge storage process, and higher electronic conductivity. Our recent work has explored using γ-Fe2O3 nanosheets for sodium-ion battery cathodes. The understanding of the unique electrochemical properties, factors that stabilize the nanosheet form, and distinct charge storage mechanism of iron oxide nanosheets furthers the design of improved charge storage materials with improved capacities, rate capabilities, and lower cost.
(Invited) Three-Dimensional Carbon Nanostructures for Advanced Rechargeable Batteries
Authors: Choi Wonbong 
Published: February 2020

Next-generation energy storage devices, such as Li-ion batteries (LIBs), demand high energy, power and better safety. Conventional graphite anode falls short of fulfilling all these necessities. Carbon nanostructural materials (graphene and carbon nanotubes) have gained the spotlight as promising anode materials for energy storage; they exhibit unique physico-chemical properties such as large surface area, short Li+ ion diffusion length, and high electrical conductivity, in addition to their long-term stability. Among all published literatures in Li-ion battery, nanostructured carbon materials occupy ~ 70%. Such an impressive figure signifies high interest and promising future of this class of materials in energy storage devices and compels us to look into the involved issues deeply. Carbon-nanostructured materials have issues with low areal and volumetric densities for the practical applications in electric vehicles, portable electronics, and power grid systems, which demand higher energy and power densities. One approach to overcoming these issues is to design and apply a three-dimensional (3D) electrode accommodating a larger loading amount of active anode materials while facilitating Li+ ion diffusion. Furthermore, 3D nanocarbon frameworks can impart a conducting pathway and structural buffer to high-capacity non-carbon nanomaterials, which results in enhanced Li+ ion storage capacity.
In this presentation, the current status of the design and fabrication of 3D carbon nanostructures will be reviewed. Our recent progress on 3D carbon nanomaterials for LIBs and Li-S batteries will be presented. Finally, the performance of 3D carbon nanomaterials based LIBs and Li-S batteries will be presented along with their mechanistic analysis and the perspective of practical applications in devices and systems.

Figure 1