bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decoupling the Role of Anion and Solvent on Mg Electrodeposition Efficiency through Interfacial Speciation Determination
Authors: Zavadil Kevin R , Hahn Nathan T , Feng Xuefei , Anquillare Emma , Guo Jinghua , Seguin Trevor , Persson Kristin A 
Published: February 2020

Chemistries based on divalent working cations, such as Mg, are one class where significant effort is required to develop reductively and oxidatively stable electrolytes to support high efficiency metal deposition and cation insertion for practical energy storage systems beyond Li ion batteries. A growing body of literature exists describing bulk Mg(II) speciation over a range of electrolyte types providing insight into the origin of parasitic reactions that limit cell efficiency and overall performance. Bulk Mg(II) speciation can be argued to be an approximate descriptor of electrolyte stability at best, as the interfacial cation-anion-solvent coordination complex is what actually determines the consequences and efficiency of electron transfer. Limited knowledge is reported for interfacial Mg(II) coordination complexes, in part, due to limited available operando probes capable of discriminating between the coordination complexes at the electrode surface and within the bulk of the electrolyte. In this paper, we demonstrate the use of fluorescent and electron yield modes of operando x-ray absorption spectroscopy (XAS) to determine interfacial composition as a function of potential for select Mg(II)-anion-ether systems. We further conduct systematic variation in the coordination strength (e.g., donicity) and coordination diversity (e.g., mono- vs multi-dentate) of anions and ethers with respect to the divalent cation as a means of decoupling the role of anion and solvent in defining stability. Comparison of spectroscopic responses of Mg(II) with Zn(II) allow for additional modulation in anion/solvent coordination enthalpy further clarifying the roles of anion and solvent. The ability of XAS to discriminate early stage interphase formation at the anode providing chemical signatures of parasitic reaction will also be discussed. The methodology presented is equally applicable to electrolyte oxidative stability at the cathode, laying the foundation for design of electrolytes with suitable stability for practical, high energy density Mg ion batteries.
This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525.
Climate-Immune Extreme Fast Charging of High Energy Li-Ion Batteries
Authors: Yang Xiao-Guang , Liu Teng , Ge Shanhai , Wang Chao-Yang 
Published: February 2020

Fast charging is the enabler of mainstream adoption of electric vehicles (EVs). There is a race worldwide for building fast charging stations with the power up to 350kW, which are able to charge a 200-mile-range EV at 6C (10 minutes). State-of-the-art EV batteries (cell-level energy density >200 Wh/kg) could only withstand 2C (30 minutes) charging due to the issue of lithium plating. Even worse, the charge rate must be dramatically reduced at low temperatures to prevent lithium plating.
Most recently, our group presented a controllable cell structure that enables lithium plating free (LPF) fast charging at all temperatures. [1] The key is to charge a cell always above a temperature that can prevent lithium plating. A rapid heating step will be performed before charging if the cell temperature is low. It is demonstrated that a 9.5Ah pouch cell with an energy density of 170 Wh/kg could be charged by 80% state of charge in 15 minutes even at -50oC, an extremely low temperature at which all conventional Li-ion cells would cease to work. Furthermore, the LPF cell sustained 4500 cycles of 15-min fast charging at 0oC with <20% capacity loss, which is equivalent to >12 years and >280,000 miles of EV lifetime, whereas a baseline conventional cell at the same condition only survived 50 cycles.
Based on the LPF cell structure, we proposed an approach to enable 10-min extreme fast charging (XFC) of high energy EV cells. By numerical analysis, we revealed that the optimal temperature for Li-ion battery charging increases with the increase of charge rate and energy density. [2] Thus, we are now partnering with the U.S. Department of Energy (DOE) to develop an XFC battery that is charged at high temperatures (>60oC). The target is to achieve 6C charging of >225 Wh/kg cells with a life of >1000 cycles at <20% capacity loss.
In this talk, we will give a comprehensive discussion of the LPF cell structure and operating strategy. We will also share our latest progress on the development of XFC cells.

References

[1] X.G. Yang, G. Zhang, S. Ge, C.Y. Wang, Proc. Natl. Acad. Sci. U.S.A. 115 (2018) 7266-7271.
[2] X.G. Yang, C.Y. Wang, J. Power Sources 402 (2018) 489-498.
Influence of Additives on Formation of through-Si Via in Si Substrate Using Metal Assisted Chemical Etching
Authors: Shimizu Tomohiro , Hanatani Syunsuke , Yorioka Takuya , Niwa Ryosuke , Ito Takeshi , Shingubara Shoso 
Published: February 2020

Recently, metal assisted chemical etching (MacEtch) attracts attention to fabricate a nano/microscale structures in Si substrate, such as nanowire and nanohole arrays. In this method, using a noble metal as a catalyst, only Si under the catalyst is selectively etched in the etching solution. Several papers have been already reported on the formation of microscale patterning using MacEtch. However, it is difficult to obtain high aspect vertical holes using MacEtch process because of its instability of etching direction for prolonged process as shown in figure (a). In this study, we present a new approach using surfactant agents as an additive in MacEtch solution to obtain vertical Si holes in Si substrates. Microscale holes were prepared in Si (100) substrates using the MacEtch process with a disc-shape patterned Au catalyst. The patterned Au discs ( 10 μm in diameter), which were deposited on a Ti / Si substrate using a photolithography lift-off process. For the MacEtch process, a mixture of hydrofluoric acid (HF), hydrogen peroxide (H2O2) and deionized water was used as the base etching solution. The PEG was added to the etching solution as an additive. The MacEtch of the Si substrate with patterned Au were performed for 120 min at 40 oC in the etching solution. Figure (a) shows cross-sectional SEM images of typical morphology of etched Si using MacEtch process without PEG in the etching solution. The etching direction of Si were changed during MacEtch as indicated with dashed arrow in Fig. (a), and these phenomena were observed in more than 60 % Si holes etched with MacEtch without PEG. Adding PEG in the etching solution, drastic improvement in verticality of etched Si holes were observed. Almost all holes were vertically etched to the Si substrate in PEG samples, and typical cross-sectional image of the etched holes is shown in Fig. (b). Fig. (c) and (d) shows enlarged image of Au catalyst films after MacEtch process. The catalyst in the bended hole prepared without PEG was deformed and partially detached from Si substrate, shown in Fig. (c). In contrast, in the case of straight holes etched with PEG shown in Fig. (d), the catalyst tightly contacted to the substrate, and showed relatively less defamation. Thus, there is a strong correlation between defamation of catalyst and formation of bended hole.
The detailed mechanism of PEG additive in etching solution during Macetch process and the MacEtch results using other surfactants as additives will be presented.

Figure 1
(Invited) Role of Domain Purity in Non-Fullerene Acceptor Based Organic Solar Cells
Authors: Mukherjee Subhrangsu , DeLongchamp Dean M 
Published: February 2020

The field of non-fullerene organic solar cells (OSC) has experienced rapid development during the past few years, mainly driven by the development of novel non-fullerene acceptors and matching donor semiconductors with device efficiencies approaching 15%. However, organic solar cell material development has progressed via a trial-and-error approach with limited understanding of the materials’ structure–property relationships and the underlying device physics of non-fullerene devices. In addition, the availability of hundreds of donor and acceptor semiconductors creates a large pool of possible donor–acceptor combinations, which poses a daunting challenge for rationally screening material combinations. Resonant soft X-ray scattering (RSoXS) has proven to be a powerful technique to measure domain purity in OSC active layer blends. In polymer-fullerene systems, RSoXS has shown that higher average domain purity is generally correlated to device performance. A simple interpretation of RSoXS purity measurements is complicated by the consideration that real morphologies may be composed of three or more phases, with mixed amorphous regions in addition to relatively pure, aggregated donor and acceptor domains. Whilst charges are understood to migrate to the aggregated domains due to a favorable electronic landscape, these charges might be effectively trapped in aggregates if there is insufficient number of percolating pathways in the amorphous mixed regions. Conversely, if the mixed regions have a composition much beyond the percolation threshold or if the volume faction of the mixed regions is large, then recombination is enhanced. Therefore, understanding the role of domain purity over different length scales and controlling the mixed amorphous phase for maximum charge creation and minimum recombination remains a principal challenge for non-fullerene OSCs.
We will summarize several of our RSoXS studies that compare non-fullerene acceptor based organic solar cells having different primary chemical structures of the constituents and with significant processing variations. Our analysis suggests that mixed regions are often detrimental to good performance in these systems, typically having a pronounced negative impact on FF. Optimizing performance continues to be a delicate balance of possibly competing factors and the volume fraction of the ideal morphology remains to be determined. However, the miscibility of blend components, which might be probed using near-edge X-ray absorption spectroscopy as a screening tool, can guide expectations of achievable phase purity and ultimately the achievable performance of the active layer.
Improved Electron Injection and Transport in Semiconducting Polymers By Doping with Guanidino-Functionalized Aromatic Compounds
Authors: Schneider Severin , Lorenz Roxana , Himmel Hans-Joerg , Zaumseil Jana 
Published: February 2020

Efficient and stable n-dopants are still rare but highly desired for organic electronics and thermoelectrics. Many high mobility, n-type semiconducting polymers still show some hole transport, which is unwanted for applications in complementary inverters, as it gives rise to increased power dissipation. The use of n-type contact dopants that block the injection of holes is thus beneficial. We successfully applied 1,2,4,5-tetrakis(tetramethylguanidino)benzene (ttmgb), a guanidino-functionalized aromatic (GFA) compound, as a strong two-electron donor to networks of single-walled carbon nanotube field-effect transistors to create purely n-type devices with high electron mobilities and high on/off current ratios [1]. Here, we demonstrate the versatility of this dopant by applying it to the well-known n-type (but still slightly ambipolar) polymer semiconductor P(NDI2OD-T2).The dopant ttmgb can be processed directly from solution, which leads to significantly improved device characteristics. Additionally, we show that vapor deposition of ttmgb is another pathway to high-performance injection layers. In all cases, the injection of electrons and their mobility is significantly improved compared to the untreated reference samples. In addition, the injection of holes is blocked by ttmgb2+ on the electrode surface, which enables the fabrication of solely n-type FETs. Contact doping with ttmgb and other GFAs could potentially also be used on other semiconducting materials, e.g. for two-dimensional transition metal dichalcogenides, and may find widespread application in high performance thin film electronics.
[1] Schneider et al., ACS Nano
2018, 12 (6), 5895-5902

Figure 1
(Invited) A Simple and Efficient Solution-Based Technique to Electrically Dope Organic Semiconductors
Authors: Larrain Felipe A. , Fuentes-Hernandez Canek , Chou Wen-Fang , Rodriguez-Toro Victor A. , Kippelen Bernard 
Published: February 2020

The printed electronics industry offers a paradigm change in manufacturing, cost and environmental impact when compared to the conventional semiconductor industry. Printed electronic devices are expected to be mass-produced from less-energy-demanding processes over large areas and on flexible substrates, with techniques that closely resemble the well-known mass production of printed media on paper.
Still, critical to the widespread of these devices is the ability to convert lab produced “champion” figures into reliable industrial-scale products. The well-established strategies for the design and fabrication of efficient lab-scale printed electronics are not always compatible with large-area manufacturing, where several additional requirements must be met.
Solution-based electrical doping of organic semiconductors has received increased attention as a technique with the potential to comply with some of these additional requirements. Stable ink-type formulations of dopant, semiconductor and solvents have been reported, some of which may be compatible with roll-to-roll coating. Yet, the ability to fabricate vertical doping gradients, critical to maintain optimal optoelectronic performance at reduced cost, has proven challenging. Vertical doping gradients would reduce the amount of coating steps without a loss in optoelectronic device functionality, simplifying manufacturing and preventing defects to propagate.
In 2017 we reported a simple technique to fabricate vertical electrical p-type doping gradients in organic semiconductor films by dipping them in solutions. Still, the initial approach, which involved 12-molybdophosphoric acid (‘PMA’ dopant) and nitromethane (processing solvent), was highly solvent selective, and the use of nitromethane was found limiting. Thus, in 2018, our team replaced nitromethane with acetonitrile and showed that the PMA-acetonitrile solution became stable in air without losing its doping ability. Furthermore, organic solar cells fabricated using the updated approach showed longer air stability.
In this talk we will start by discussing the basics of the solution-based technique to electrically p-type organic semiconductors using PMA, and compare it against similar, well-studied approaches. Then, we will emphasize on our latest insights on the path to unravel, from a molecular perspective, how organic semiconductors are doped down to a limited depth from solution, using PMA molecules. That is, what is the interplay between the organic film and PMA molecules in solution that leads to p-type electrical doping of the semiconducting layer? Additionally, what are the key parameters that determine the efficiency and extent of the process?
(Invited) High-Frequency Operation of Vertical Organic Field-Effect Transistors
Authors: Kleemann Hans 
Published: February 2020

Organic thin-film transistors (OTFT) are attracting great interest in view of flexible electronics enabling future revolutionizing applications such as flexible displays or wearable electronics. Due to the poor intrinsic charge carrier transport in organic semiconductor thin-films, the main target of development in the last two decades was to find suited semiconductor materials offering a higher charge carrier mobility. However, although record values of clear beyond 10cm²/Vs have been demonstrated, key transistor parameters such as the transconductance or transition frequency have not been improved substantially. In consequence, the performance of today's OTFTs is still too low for many demanding electronic applications.
In the last couple of years we have develop various architectures for vertical organic transistor offering superior current driving capabilities compared to state-of-the-art horizontal organic TFTs. Within this 3-dimensional VOFET geometry, the channel length is not defined by the applied patterning technique but rather by the thickness of the organic layers, typically <300nm, separating the vertically stacked source and drain electrodes. This ultra-short channel configuration allows for superior current driving, however, it is usually accompanied by undesired short-channel effects such as loss of saturation and an increased off-current level.
In my presentation I introduce the VOFET concept and highlight the development of optimized transistor geometries leading to superior performance with an on/off ratio>10⁷, transition frequency approaching 100MHz and excellent operational stability.
In the second part of the contribution I focus on the potential of VOFETs for active matrix OLED (AMOLED) display driving. Comparing typical TFT design guidelines for vertical and horizontal TFTs, it can be deduced that the VOFET design leads to a considerable reduction of area consumption within a pixel which ultimately enables a higher display resolution and a lower power consumption.
The concept of vertical transistors is not restricted to organic semiconductors. Hence, I discuss in the third part of my presentation the potential of high mobility metal-oxide semiconductors for vertical thin-film transistors for GHz operation.
(Invited) Recent Developments in Contact-Controlled Transistors
Authors: Sporea Radu Alexandru 
Published: February 2020

An effective route to achieving high gain and low saturation voltage in thin-film transistors is by controlling the current by modulating the conductivity of the source contact area [1-3], potentially at the expense of operating speed. Such devices, called source-gated transistors (SGTs) are easily made using the usual techniques, in a variety of organic and inorganic semiconductor technologies, with the requirement that a potential barrier is reliably engineered at the source electrode. Most often, this barrier results from the presence of a Schottky contact [4], which has been proven beneficial in similar devices [5]. As this type of TFT gains popularity, novel ideas which leverage both the device physics and the specifics of the fabrication process are emerging [6].
In this paper we will discuss recent advances in device architecture and highlight important design decisions specific to the envisaged application. Since the contact injection area plays an important part in this type of devices, it is an essential design parameter. Traditionally, contact overlap should be minimized to reduce capacitance, but in SGTs it may be advantageous to purposely increase gate-to-source overlap. Interesting circuit behaviour results from the sizing of this parameter [7] and could be useful in designing circuit blocks which take advantage of this factor, in contrast with conventional TFT circuit design. This reasoning is especially relevant to pixel circuits where a storage capacitor is required in the circuit between these two electrical nodes: circuit optimization necessarily includes electrical characteristics and layout area.
In many applications, the versatility and robustness of these contact-controlled devices outweighs their reduced operating frequency, and their ease of fabrication recommends them for high-gain circuits where uniformity of performance is critical.
[1] S. D. Brotherton, Introduction to Thin Film Transistors: Physics and Technology of TFTs, Springer, 453–480, Cham (2013).
[2] A. Valletta et al., J. Appl. Phys. 114 064501 (2013).
[3] R. A. Sporea et al., Scientific Reports
4 4295 (2014).
[4] N. Papadopoulos et al., Proc CICC 2017 (2017).
[5] Lee, S. and A. Nathan, Science
354, 302 (2016).
[6] L. Wang et al., Appl. Phys. Lett.
110, 152105 (2017).
[7] J. M. Shannon et al., IEEE Trans. Electron Devices, 60, 2444–2449 (2013).
[8] R. Drury et al., Proc. CAD-TFT 2018, Shenzhen, China (2018).
Effects of Doping States of Polyaniline Thin Films on Their Photo-Responsive Properties
Authors: Choi Jongwan 
Published: February 2020

Polyaniline (PANI) has been of great interest in development of conducting polymers because of easy bulk-scale polymerization and relatively high electrical conductivity. The physical and electrical characteristics of PANI largely depend on its protonation-induced doping states. The protonation of imine sites upon acid doping leads to the formation of a conductive polaron lattice along the backbone. The effects of acid dopants on dielectric, optoelectronic, and thermoelectric properties of PANI have recently been investigated.
In this study, we investigate the effects of doping/dedoping states of PANI thin films on their photo-responses under laser irradiation in visible and near-infrared regions. The doping levels were controlled by treating as-prepared, acid-doped PANI with aqueous ammonia solutions. Spectroscopic analyses confirmed the changes in the doping states by evolution or decrease of characteristic peaks. The electrical and photo-responsive properties were significantly affected by the doping states of the PANI thin films. The photocurrent and photovoltage under irradiation of controlled wavelengths from various laser sources were measured. While the photocurrent followed the trends of electrical conductivity upon dedoping, the photovoltage was related to the absorption and photocharge generation of the PANI samples.