bluuebunny/crossref_metadata_2025 huggingface dataset:
Synergism of Rare Earth Trihydrides and Graphite in Lithium Storage: Evidence of Hydrogen‐Enhanced Lithiation
Authors: Zheng Xinyao , Yang Chengkai , Chang Xinghua , Wang Teng , Ye Meng , Lu Jing , Zhou Henghui , Zheng Jie , Li Xingguo
Published: December 2017

The lithium storage capacity of graphite can be significantly promoted by rare earth trihydrides (REH3, RE = Y, La, and Gd) through a synergetic mechanism. High reversible capacity of 720 mA h g−1after 250 cycles is achieved in YH3–graphite nanocomposite, far exceeding the total contribution from the individual components and the effect of ball milling. Comparative study on LaH3–graphite and GdH3–graphite composites suggests that the enhancement factor is 3.1–3.4 Li per active H in REH3, almost independent of the RE metal, which is evident of a hydrogen‐enhanced lithium storage mechanism. Theoretical calculation suggests that the active H from REH3can enhance the Li+binding to the graphene layer by introducing negatively charged sites, leading to energetically favorable lithiation up to a composition Li5C16H instead of LiC6for conventional graphite anode.
Acoustic Fabrication via the Assembly and Fusion of Particles
Authors: Melde Kai , Choi Eunjin , Wu Zhiguang , Palagi Stefano , Qiu Tian , Fischer Peer
Published: December 2017

Acoustic assembly promises a route toward rapid parallel fabrication of whole objects directly from solution. This study reports the contact‐free and maskless assembly, and fixing of silicone particles into arbitrary 2D shapes using ultrasound fields. Ultrasound passes through an acoustic hologram to form a target image. The particles assemble from a suspension along lines of high pressure in the image due to acoustic radiation forces and are then fixed (crosslinked) in a UV‐triggered reaction. For this, the particles are loaded with a photoinitiator by solvent‐induced swelling. This localizes the reaction and allows the bulk suspension to be reused. The final fabricated parts are mechanically stable and self‐supporting.
Thermally Induced Bending of ReS2 Nanowalls
Authors: Zhang Qin , Wang Wenjie , Zhang Jiaqian , Zhu Xiaohui , Fu Lei
Published: December 2017

Among the variety of stimuli‐responsive materials, temperature‐responsive materials (TRMs) can adapt to the surrounding environment in the presence of a thermal stimulus, and they have attracted considerable attention in sensors, actuators, and surface engineering. However, polymers, as the most representative TRMs, are far from ideal with respect to long‐term reliability and durability. Here, for the first time, an inorganic material, ReS2, is analyzed, which possesses an unexpected temperature‐responsive behavior that is triggered by stable and reversible thermally induced bending (TIB). Due to thermal fluctuations in the ReS2 layers, intrinsic ripples tend to aggravate rapidly with rising temperature. Then, the weak interlayer interaction of ReS2 is further weakened, thus resulting in interlayer sliding. Due to a decrease in bending rigidity with increasing temperature, out‐of‐plane bending spontaneously occurs in the ReS2 layers. Interestingly, this TIB of ReS2 can recover to its initial configuration when the temperature drops, which is further confirmed by the reversible wetting measurement. Above all, the TIB behavior of ReS2 exhibits great potential in smart applications, such as smart windows and microfluidic devices, and fills the significant gaps of inorganic TRMs.
Highly Stretchable and Reliable, Transparent and Conductive Entangled Graphene Mesh Networks
Authors: Han Jaehyun , Lee Jun‐Young , Lee Jihye , Yeo Jong‐Souk
Published: December 2017

A highly stretchable and reliable, transparent and conductive entangled graphene mesh network (EGMN) exhibits an interconnected percolation network, as usually shown in 1D nanowires, but with the electrical, mechanical, and thermal properties of 2D graphene. The unique combination of the 2D material properties and the network structure of wrinkled, waved, and crumpled graphene enables the EGMN to demonstrate excellent electrical reliability, mechanical durability, and thermal stability, even under harsh environmental and external conditions such as very high temperature, humidity, bending, and stretching. Specifically, after 100 000 cycles of bending with radius of 2 mm, the EGMN maintains its resistance similar to its initial value. The EGMN shows a steady monotonic response in resistance to strain cycles of 50 000 times with nearly constant gauge factors of 0.76, 1.67, and 2.55 at 10%, 40%, and 70% strains, respectively. Moreover, the EGMN shows very little change in resistance with the temperature increasing up to 1000 °C, by in situ thermal analysis with transmission electron microscopy and also by long‐term stability testing at 70 °C and 70% relative humidity for 30 d. These results demonstrate that this novel entangled graphene mesh network can significantly broaden the application areas for various types of wearable and stretchable devices.
Growth and Characterization of 3D Flower‐Like β‐NiS on Carbon Cloth: A Dexterous and Flexible Multifunctional Electrode for Supercapattery and Water‐Splitting Applications
Authors: Surendran Subramani , Selvan Ramakrishnan Kalai
Published: December 2017

Evolution of 3D nanostructures is luring a great deal of importance owing to their eccentric structures that create plenty of rooms to grasp massive volume of charges. Here, a distinct multifunctional binder‐free flexible electrode is developed by arrays of flower‐like β‐NiS nanostructures over flexible carbon cloth (β‐NiS@CC) by the in situ hydrothermal method. It unveils an ultimate areal capacity of 1.654 C cm−2 (827 C g−1) at 1 mA cm−2, which seems to be the highest among the reported NiS so far. The fabricated flexible supercapattery gadget delivers a remarkable energy density of 38 µWh cm−2 at a power density of 800 µW cm−2. Due to immense mechanical strength and resilience of 3D flower‐like morphology, it is further exposed as an economical bifunctional electrocatalyst. Both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) exhibit a significant burst of the enormous quantity of gas bubbles at the low overpotentials of 320 and 278 mV, respectively, to achieve a current density of 20 mA cm−2. Further, the developed laboratory scale water electrolyzer offers a low cell voltage of 1.65 V to accomplish a water‐splitting current density of 10 mA cm−2. Henceforth, the multifunctional 3D flower‐like β‐NiS electrode is demonstrated by defining its potential use in real‐world appliances.
Construction of a Multiway Carbon Nanotube Loudspeaker with Finely Tunable Resonance Frequencies
Authors: Shin Eui Joong , Park Soo Yeon , Kim Choong Sun , Cho Byung Jin , Choi Jung‐Woo
Published: December 2017

The sound pressure generated by thermo‐acoustic (TA) loudspeakers is proportional to the frequency of the sound. This characteristic yields a low sound pressure level (SPL) in the low‐frequency region, hindering the practical application of TA loudspeakers. The limitation of low SPL is approached by using a resonating structure, in which a TA sound generator, such as multiwalled carbon nanotube sheet, is enclosed within a cavity covered by a vibrating plate. However, the cavity‐plate resonator produces an amplified SPL only around the resonating frequency, so its operating frequency bandwidth is narrow. Hence, a multiway TA loudspeaker consisting of multiple resonators that can amplify sound over a wide frequency range is designed. An accurate mechanical model is presented for predicting the resonance frequency and it shows that the behavior of resonators designed from the proposed model matches the theory well. The model enables the fine‐tuning of resonances through the application of different materials for a resonator plate and by changing the structural dimensions. A crossover network for combining multiple TA resonators is designed, and the total frequency response shows a flat frequency response with amplified SPL. These improvements open up possibilities for the use of TA loudspeakers as a practical audio device.
Digital Aerosol Jet Printing for the Fabrication of Terahertz Metamaterials
Authors: Jahn David , Eckstein Ralph , Schneider Lorenz Maximilian , Born Norman , Hernandez‐Sosa Gerardo , Balzer Jan C. , Al‐Naib Ibraheem , Lemmer Uli , Koch Martin
Published: December 2017

In this paper the use of aerosol jet printing as a fabrication and rapid prototyping method for terahertz metamaterials is presented. Since this technique combines the very precise deposition of metallic inks with line widths down to 10 µm and the use of digitally generated tool paths, it is highly suitable for fabricating arbitrary 2D microstructures for terahertz applications. The fabrication of a metamolecule composed of four closed ring resonators with two different radii on conventional polyester foil is shown. Furthermore, the metamaterials are characterized thoroughly using microscopic images, confocal microscopy, and terahertz time‐domain spectroscopy, which demonstrate impressively the suitability of this fabrication technology for terahertz applications. For an additional validation the experimentally gathered data with numerical simulations are compared.
A Breathable and Screen‐Printed Pressure Sensor Based on Nanofiber Membranes for Electronic Skins
Authors: Yang Wei , Li Nian‐Wu , Zhao Shuyu , Yuan Zuqing , Wang Jiaona , Du Xinyu , Wang Bin , Cao Ran , Li Xiuyan , Xu Weihua , Wang Zhong Lin , Li Congju
Published: December 2017

In recent years, skin‐like pressure sensors with high sensitivity and excellent flexibility are widely demonstrated for electronic skins. However, most of the reported skin‐like pressure sensors are still based on airtight films, resulting in limited air permeability. Herein, cost‐effective and capable processes of large‐scale production are reported for lightweight and breathable pressure sensors based on nanofiber membranes (NM). The pressure sensor is composed of a layer‐by‐layer structure of poly(vinylidene fluoride) NM for substrates, silver nanowires for electrodes, and thermoplastic polyurethane NM for the dielectric layer through screen printing and ultrasonic bonding techniques. Benefiting from the high porosity of NM, the capacitive pressure sensor possesses unique performance, including a superior sensitivity of 4.2 kPa−1, a fast response time (<26 ms), an ultralow detection limit (1.6 Pa), and excellent breathability (Gurley value = 17.3 s/100 mL). Furthermore, the pressure sensor is not only applicable to monitor human physiological signals, but also to detect spatial pressure distribution. These results indicate that the breathable and screen‐print pressure sensor is promising for electronic skins with air permeability.
Interactive Nanogel Marking at the Microscale for Security and Traceability Applications
Authors: Teulon Lauryanne , Palleau Etienne , Morales Daniel , Poirot David , Ressier Laurence
Published: December 2017

An original approach named Nanogel Marking is addressed herein to propose new alternatives to fight counterfeiting and forgery by improving the traceability of objects and documents and enabling secured authentication. This technique can be used to write or code information, logos, or patterns of a desired design at the microscale using poly(NIPAAm‐co‐AAc) nanogels as an envirointelligent biocompatible “ink.” Nanogel marking features multiple functions, such as reversibility (write/erase properties), color changing capabilities, and recycling capabilities. Based on soft lithography methods, this nanogel marking technique also overcomes industrial limitations since it is fast, sustainable, and scalable on surfaces as large as a 4 in. wafer, enabling the fabrication of hundreds of thousands of nanogel markers in a few minutes.
Printing of Large‐Scale, Flexible, Long‐Term Stable Dielectric Mirrors with Suppressed Side Interferences
Authors: Bronnbauer Carina , Riecke Arne , Adler Marius , Hornich Julian , Schunk Gerhard , Brabec Christoph J. , Forberich Karen
Published: December 2017

Dielectric mirrors are wavelength‐selective mirrors which are based on thin film interference effects. Their optical band can precisely be adjusted in width, position, and reflectance by the refractive index of the applied materials, the layers' thicknesses, and the amount of deposited layers. Nowadays, they are a well‐known light management tool for efficiency enhancement in, for example, semitransparent organic solar cells (OSCs) and light guiding in organic light‐emitting diodes (OLEDs). However, most of the dielectric mirrors are still fabricated by lab‐scale techniques such as spin‐coating or physical vapor deposition under vacuum. Large‐scale, fully printed (maximum 20 × 20 cm2) dielectric mirrors with adjustable reflectance characteristics are fabricated, using temperatures of maximum 50 °C and alcohol‐based inks. According to the moderate processing conditions they can be easily deposited not only on rigid glass substrates but also on flexible foils. They show high stability against humidity, light irradiation, and temperature, positioning themselves as good candidates for applications in OLEDs and OSCs. Eventually, by simulations and experiments it is verified that a moderate degree of variations in layer thickness and surface roughness can suppress side interference fringes, while not impacting the main transmittance minimum or the main reflection maximum, respectively.
Programming Photoresponse in Liquid Crystal Polymer Actuators with Laser Projector
Authors: Wani Owies M. , Zeng Hao , Wasylczyk Piotr , Priimagi Arri
Published: December 2017

A versatile, laser‐projector‐based method is demonstrated for programming alignment patterns into monolithic films of liquid crystal polymer networks. Complex images can be photopatterned into the polymer films with sub‐100 µm resolution, using relatively short exposure times. The method is further used to devise both photochemically and photothermally driven actuators that can undergo distinct light‐induced shape changes, dictated by the programmed alignment patterns. Deformation modes such as buckling and coiling, as well as miniature robotic devices such as a gripper and a light‐responsive octopod, are demonstrated. The reported technique enables easy and cost‐effective programmable actuation with relatively high throughput, thus significantly facilitating the design and realization of functional soft robotic actuators.
Dopant‐Free and Carrier‐Selective Heterocontacts for Silicon Solar Cells: Recent Advances and Perspectives
Authors: Gao Pingqi , Yang Zhenhai , He Jian , Yu Jing , Liu Peipei , Zhu Juye , Ge Ziyi , Ye Jichun
Published: December 2017

By combining the most successful heterojunctions (HJ) with interdigitated back contacts, crystalline silicon (c‐Si) solar cells (SCs) have recently demonstrated a record efficiency of 26.6%. However, such SCs still introduce optical/electrical losses and technological issues due to parasitic absorption/Auger recombination inherent to the doped films and the complex process of integrating discrete p+‐ and n+‐HJ contacts. These issues have motivated the search for alternative new functional materials and simplified deposition technologies, whereby carrier‐selective contacts (CSCs) can be formed directly with c‐Si substrates, and thereafter form IBC cells, via a dopant‐free method. Screening and modifying CSC materials in a wider context is beneficial for building dopant‐free HJ contacts with better performance, shedding new light on the relatively mature Si photovoltaic field. In this review, a significant number of achievements in two representative dopant‐free hole‐selective CSCs, i.e., poly(3,4‐ethylene dioxythiophene):poly(styrenesulfonate)/Si and transition metal oxides/Si, have been systemically presented and surveyed. The focus herein is on the latest advances in hole‐selective materials modification, interfacial passivation, contact resistivity, light‐trapping structure and device architecture design, etc. By analyzing the structure–property relationships of hole‐selective materials and assessing their electrical transport properties, promising functional materials as well as important design concepts for such CSCs toward high‐performance SCs have been highlighted.
Nanogap‐Engineerable Electromechanical System for Ultralow Power Memory
Authors: Zhang Jian , Deng Ya , Hu Xiao , Nshimiyimana Jean Pierre , Liu Siyu , Chi Xiannian , Wu Pei , Dong Fengliang , Chen Peipei , Chu Weiguo , Zhou Haiqing , Sun Lianfeng
Published: December 2017

Nanogap engineering of low‐dimensional nanomaterials has received considerable interest in a variety of fields, ranging from molecular electronics to memories. Creating nanogaps at a certain position is of vital importance for the repeatable fabrication of the devices. Here, a rational design of nonvolatile memories based on sub‐5 nm nanogaped single‐walled carbon nanotubes (SWNTs) via the electromechanical motion is reported. The nanogaps are readily realized by electroburning in a partially suspended SWNT device with nanoscale region. The SWNT memory devices are applicable for both metallic and semiconducting SWNTs, resolving the challenge of separation of semiconducting SWNTs from metallic ones. Meanwhile, the memory devices exhibit excellent performance: ultralow writing energy (4.1 × 10−19 J bit−1), ON/OFF ratio of 105, stable switching ON operations, and over 30 h retention time in ambient conditions.
Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges
Authors: Tsao J. Y. , Chowdhury S. , Hollis M. A. , Jena D. , Johnson N. M. , Jones K. A. , Kaplar R. J. , Rajan S. , Van de Walle C. G. , Bellotti E. , Chua C. L. , Collazo R. , Coltrin M. E. , Cooper J. A. , Evans K. R. , Graham S. , Grotjohn T. A. , Heller E. R. , Higashiwaki M. , Islam M. S. , Juodawlkis P. W. , Khan M. A. , Koehler A. D. , Leach J. H. , Mishra U. K. , Nemanich R. J. , Pilawa‐Podgurski R. C. N. , Shealy J. B. , Sitar Z. , Tadjer M. J. , Witulski A. F. , Wraback M. , Simmons J. A.
Published: December 2017

Ultrawide‐bandgap (UWBG) semiconductors, with bandgaps significantly wider than the 3.4 eV of GaN, represent an exciting and challenging new area of research in semiconductor materials, physics, devices, and applications. Because many figures‐of‐merit for device performance scale nonlinearly with bandgap, these semiconductors have long been known to have compelling potential advantages over their narrower‐bandgap cousins in high‐power and RF electronics, as well as in deep‐UV optoelectronics, quantum information, and extreme‐environment applications. Only recently, however, have the UWBG semiconductor materials, such as high Al‐content AlGaN, diamond and Ga2O3, advanced in maturity to the point where realizing some of their tantalizing advantages is a relatively near‐term possibility. In this article, the materials, physics, device and application research opportunities and challenges for advancing their state of the art are surveyed.
Role of the Electrode Material on the RESET Limitation in Oxide ReRAM Devices
Authors: Schönhals Alexander , Rosário Carlos M. M. , Hoffmann‐Eifert Susanne , Waser Rainer , Menzel Stephan , Wouters Dirk J.
Published: December 2017

Metal‐oxide‐based bipolar resistive switching (BRS) redox‐based resistive switching memory (ReRAM) shows many outstanding properties making it of interest as an emerging nonvolatile memory. However, it often suffers from a low ROFF/RON ratio, while a large ratio is desired to compensate for read margin loss due to the intrinsic variability of the ReRAM cells. Understanding of the physical processes responsible for limitations of the ROFF and RON in ReRAM cells is therefore of high importance. In this paper a study on the RESET process in BRS Ta2O5‐based ReRAM cells is presented. The ROFF is found to be limited by a secondary volatile resistive switching mode that shows an opposite polarity compared to the main BRS mode. Based on results of switching kinetics measurements a physical model is proposed. It involves an oxygen exchange reaction at the metal‐oxide/active electrode interface combined with a drift‐diffusion induced migration of the resulting oxygen vacancy defects within the metal‐oxide. Incorporation of a thin oxygen‐blocking layer at the active interface allows for a suppression of the secondary switching mechanism. The improved RESET characteristic results in a strongly increased maximum ROFF. These results provide new insights into the role of the electrode material on the RESET process in BRS ReRAM cells.
Fine‐Tuned Multilayered Transparent Electrode for Highly Transparent Perovskite Light‐Emitting Devices
Authors: Wu Hua , Zhang Yu , Zhang Xiaoyu , Lu Min , Sun Chun , Bai Xue , Zhang Tieqiang , Sun Guang , Yu William W.
Published: December 2017

The high photoluminescence quantum yield, wide color tunability and narrow bandwidth of perovskite nanocrystals make them favorable for light source and display applications. Here, highly transparent green‐light‐emitting devices (LEDs) using inorganic cesium lead halide perovskite nanocrystal films as the emissive layer are reported. The effect of multilayered nanostructured transparent electrode on optical properties and performance within the LEDs is investigated by fine tuning layer thickness. The results show that the light transmission in visible region can be enhanced with this nanostructured film. These LEDs exhibited a high transmittance (average 73% over 400–700 nm) and high brightness of 2640 and 1572 cd m−2 for indium‐doped tin oxide (ITO) cathode and MoOx/Au/MoOx anode sides, respectively.
Sb2Se3 Thin‐Film Photovoltaics Using Aqueous Solution Sprayed SnO2 as the Buffer Layer
Authors: Lu Shuaicheng , Zhao Yang , Chen Chao , Zhou Ying , Li Dengbing , Li Kanghua , Chen Wenhao , Wen Xixing , Wang Chong , Kondrotas Rokas , Lowe Nathan , Tang Jiang
Published: December 2017

Sb2Se3 is a promising photovoltaic material due to its suitable bandgap, strong light absorption, simple phase, nontoxicity, and earth‐abundant constituents. Currently, most Sb2Se3 thin‐film solar cells are based on toxic CdS as the buffer layer. Here, for the first time, non‐toxic, wide‐bandgap, and chemically stable SnO2 is introduced as the buffer layer instead of CdS to build superstrate SnO2/Sb2Se3 thin‐film solar cells. The phase of sprayed SnO2 films and device band alignment are investigated in detail. SnO2 buffer layer annealed at 480 °C exhibits the lowest interfacial defect density and best device performance. Finally, 3.05% efficiency is achieved and the devices show excellent storage and light‐soaking stability. This preliminary experimental study implies that SnO2 has potential for developing high‐efficiency, stable, and environmentally friendly Sb2Se3‐based solar cells.
Self‐Assembly of Functionalized Oligothiophene into Hygroscopic Fibers: Fabrication of Highly Sensitive and Fast Humidity Sensors
Authors: Squillaci Marco A. , Cipriani Alessio , Melucci Manuela , Zambianchi Massimo , Caminati Grabriella , Samorì Paolo
Published: December 2017

A new symmetric oligothiophene exposing tetraethylene glycol (TEG)‐based side‐chains is designed and synthesized. This molecule is found to self‐assemble in solution forming supramolecular fibers, via π–π stacking between the conjugated oligothiophene backbones, which are phase segregated on the sub‐nanometer scale from the TEG side‐groups. The delocalization of the charges through the oligothiophene π–π stack ensures efficient charge transport while the hygroscopic shell, decorating the surface of the fibrillar structures, determines a certain affinity for polar molecules. Upon exposure to humidity, under environmental conditions, such supramolecular architectures are capable of reversibly absorbing and desorbing water molecules. Absorption of water molecules, due to increased environmental humidity, causes a fast and reproducible increase of the electrical current through the fibers by a factor 100 from 15% to 90% relative humidity, as measured in 2‐terminal devices. Such process is extremely fast, taking place in less than 45 ms. The humidity‐responsive characteristics of the presented oligothiophene‐based fibers can be exploited for the facile fabrication of high‐performances and solution‐processable electrical resistive humidity sensors.
High‐Mobility Regioisomeric Thieno[f,f′]bis[1]benzothiophenes: Remarkable Effect of Syn/Anti Thiophene Configuration on Optoelectronic Properties, Self‐Organization, and Charge‐Transport Functions in Organic Transistors
Authors: Oyama Tatsuya , Mori Tatsuya , Hashimoto Tomohiro , Kamiya Muneaki , Ichikawa Takahiro , Komiyama Hideaki , Yang Yu Seok , Yasuda Takuma
Published: December 2017

π‐Conjugated thienoacene‐based organic semiconductors with high charge carrier mobility and processability have been intensively pursued for electronic device applications, including organic field‐effect transistors (OFETs). Their charge carrier mobility is an important figure of merit, and is influenced not only by the intrinsic electronic structure at molecular level, but also by the molecular packing arrangement and crystallinity in the solid state. In this work, the focus is on a unique regioisomeric thienoacene system involving dialkyl‐thieno[f,f′]bis[1]benzothiophene isomers having different syn/anti thiophene configurations (syn‐ and anti‐TBBT‐8). The effects of these regioisomeric structures on the physicochemical properties, self‐organization behavior, and charge‐transport functions are systematically investigated using experimental and theoretical analyses. The structural analyses indicate that the syn‐ and anti‐TBBT‐8 isomers self‐organize into completely different packing arrangements, in the form of solution‐crystallized microribbons and thin films. The resulting charge‐transport properties are strongly dependent on the syn/anti thiophene configurations. Remarkably, solution‐processed OFETs using the syn‐TBBT‐8 isomer show high hole mobilities of up to 10.1 cm2 V−1 s−1, which are more than one order of magnitude higher than those of the anti‐TBBT‐8 isomer. This work highlights the importance of the regioisomeric molecular configuration of thienoacene‐based organic semiconductors for developing high‐performance electronic devices.
Zone‐Annealing‐Assisted Solvent‐Free Processing of Complementary Semiconducting Polymer Blends for Organic Field‐Effect Transistors
Authors: Xue Guobiao , Zhao Yan , Zhao Xikang , Li Hanying , Mei Jianguo
Published: December 2017

Semiconducting polymer thin films, which are usually formed by solution‐casting from their organic solutions, are critical in the development of flexible and printed electronics. To seek out a method that can further improve the electrical properties of semiconducting polymers and also be industrially applicable is of vital significance. In this study, the impact of zone annealing on the charge‐transport properties of diketopyrrolopyrrole‐based complementary semiconducting polymer blends in field‐effect transistor devices is investigated. An average mobility increased from 0.66 to 0.87 cm2 V−1 s−1, with a highest of 1.6 cm2 V−1 s−1, is observed. It is also demonstrated that zone annealing can be integrated with melt processing to realize a solvent‐free process for polymer thin films for organic field‐effect transistors (OFETs) and achieve improved charge transport characteristics with a record mobility of 0.54 cm2 V−1 s−1 among melt‐processed OFETs. This work provides an alternative, green, and sustainable processing method to advance polymer‐based organic electronics.
Fullerene‐Based Materials for Photovoltaic Applications: Toward Efficient, Hysteresis‐Free, and Stable Perovskite Solar Cells
Authors: Deng Lin‐Long , Xie Su‐Yuan , Gao Feng
Published: December 2017

Perovskite solar cells are promising candidates for next‐generation photovoltaics. Fullerenes and their derivatives can act as efficient electron transport layers, interfacial modification layers, and trap state passivators in perovskite solar cells, all of which play an important role in increasing efficiency, reducing current hysteresis, and enhancing device stability. Herein, recent progress in the use of fullerenes and their derivatives in perovskite solar cells is reviewed, with a particular emphasis on fullerene chemical structures that affect device performance. Potential fullerene candidates that could further improve device performance and stability are also discussed.
High‐Performance Solar Steam Device with Layered Channels: Artificial Tree with a Reversed Design
Authors: Liu He , Chen Chaoji , Chen Guang , Kuang Yudi , Zhao Xinpeng , Song Jianwei , Jia Chao , Xu Xu , Hitz Emily , Xie Hua , Wang Sha , Jiang Feng , Li Tian , Li Yiju , Gong Amy , Yang Ronggui , Das Siddhartha , Hu Liangbing
Published: December 2017

Solar steam generation, combining the most abundant resources of solar energy and unpurified water, has been regarded as one of the most promising techniques for water purification. Here, an artificial tree with a reverse‐tree design is demonstrated as a cost‐effective, scalable yet highly efficient steam‐generation device. The reverse‐tree design implies that the wood is placed on the water with the tree‐growth direction parallel to the water surface; accordingly, water is transported in a direction perpendicular to what occurs in natural tree. The artificial tree is fabricated by cutting the natural tree along the longitudinal direction followed by surface carbonization (called as C‐L‐Wood). The nature‐made 3D interconnected micro‐/nanochannels enable efficient water transpiration, while the layered channels block the heat effectively. A much lower thermal conductivity (0.11 W m−1 K−1) thus can be achieved, only 1/3 of that of the horizontally cut wood. Meanwhile, the carbonized surface can absorb almost all the incident light. The simultaneous optimizations of water transpiration, thermal management, and light absorption results in a high efficiency of 89% at 10 kW m−2, among the highest values in literature. Such wood‐based high‐performance, cost‐effective, scalable steam‐generation device can provide an attractive solution to the pressing global clean water shortage problem.
Bimetallic Zeolitic Imidazolite Framework Derived Carbon Nanotubes Embedded with Co Nanoparticles for Efficient Bifunctional Oxygen Electrocatalyst
Authors: Li Yinle , Jia Baoming , Fan Yanzhong , Zhu Kelong , Li Guangqin , Su Cheng‐Yong
Published: December 2017

Bifunctional oxygen catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with high activities and low‐cost are of prime importance and challenging in the development of fuel cells and rechargeable metal–air batteries. This study reports a porous carbon nanomaterial loaded with cobalt nanoparticles (Co@NC‐x/y) derived from pyrolysis of a Co/Zn bimetallic zeolitic imidazolite framework, which exhibits incredibly high activity as bifunctional oxygen catalysts. For instance, the optimal catalyst of Co@NC‐3/1 has the interconnected framework structure between porous carbon and embedded carbon nanotubes, which shows the superb ORR activity with onset potential of ≈1.15 V and half‐wave potential of ≈0.93 V. Moreover, it presents high OER activity that can be further enhanced to over commercial RuO2 by P‐doped with overpotentials of 1.57 V versus reversible hydrogen electrode at 10 mA cm−2 and long‐term stability for 2000 circles and a Tafel slope of 85 mV dec−1. Significantly, the nanomaterial demonstrates better catalytic performance and durability than Pt/C for ORR and commercial RuO2 and IrO2 for OER. These findings suggest the importance of a synergistic effect of graphitic carbon, nanotubes, exposed Co–Nx active sites, and interconnected framework structure of various carbons for bifunctional oxygen electrocatalysts.
Review on Challenges and Recent Advances in the Electrochemical Performance of High Capacity Li‐ and Mn‐Rich Cathode Materials for Li‐Ion Batteries
Authors: Nayak Prasant Kumar , Erickson Evan M. , Schipper Florian , Penki Tirupathi Rao , Munichandraiah Nookala , Adelhelm Philipp , Sclar Hadar , Amalraj Francis , Markovsky Boris , Aurbach Doron
Published: December 2017

Li and Mn‐rich layered oxides, xLi2MnO3·(1–x)LiMO2 (M=Ni, Mn, Co), are promising cathode materials for Li‐ion batteries because of their high specific capacity that can exceed 250 mA h g−1. However, these materials suffer from high 1st cycle irreversible capacity, gradual capacity fading, low rate capability, a substantial charge‐discharge voltage hysteresis, and a large average discharge voltage decay during cycling. The latter detrimental phenomenon is ascribed to irreversible structural transformations upon cycling of these cathodes related to potentials ≥4.5 V required for their charging. Transition metal inactivation along with impedance increase and partial layered‐to‐spinel transformation during cycling are possible reasons for the detrimental voltage fade. Doping of Li, Mn‐rich materials by Na, Mg, Al, Fe, Co, Ru, etc. is useful for stabilizing capacity and mitigating the discharge‐voltage decay of xLi2MnO3·(1–x)LiMO2 electrodes. Surface modifications by thin coatings of Al2O3, V2O5, AlF3, AlPO4, etc. or by gas treatment (for instance, by NH3) can also enhance voltage and capacity stability during cycling. This paper describes the recent literature results and ongoing efforts from our groups to improve the performance of Li, Mn‐rich materials. Focus is also on preparation of cobalt‐free cathodes, which are integrated layered‐spinel materials with high reversible capacity and stable performance.
Comparing competitive toughness to benchmark outcomes in retail oligopoly pricing
Authors: Sakamoto Ryo , Stiegert Kyle
Published: December 2017

Past research on pricing in imperfectly competitive markets conventionally assumes that competition operates through a specific quantity or a price game. However, most markets do not function in a manner consistent with a single static benchmark. Methods to overcome this problem have largely been rejected by the research community (i.e., conjectural variations). The primary objective of our research is to introduce a new methodology for measuring imperfect competition under product differentiation in consumer goods. We develop the empirical procedures for estimating a competitive toughness model as proposed by d'Aspremont, Dos Santos Ferreira, and Gérard‐Varet. This approach presents a theoretically grounded procedure that measures market power in an empirically tractable framework. We estimate the proposed model on the retail market for ground coffee. Our results suggest that market power is understated in a model that imposes the restriction of Bertrand pricing. The results suggest that this could be a promising approach for use in many applications. [EconLit citations: D43, L13, K21]
Multilevel Monte Carlo applied to chemical engineering systems subject to uncertainty
Authors: Kimaev Grigoriy , Ricardez‐Sandoval Luis A.
Published: December 2017

The aim of this study is to evaluate the performance of Multilevel Monte Carlo (MLMC) sampling technique for uncertainty quantification in chemical engineering systems. Three systems (a mixing tank, a wastewater treatment plant, and a ternary distillation column, all subject to uncertainty) were considered. The expected values of the systems' observables were estimated using MLMC, Power Series and Polynomial Chaos expansions, and standard Monte Carlo (MC) sampling. The MLMC technique achieved results of significantly greater accuracy than other methods at a lower computational cost than standard MC. This study highlights the nuances of adapting the MLMC technique to chemical engineering systems and the advantages of using MLMC for uncertainty quantification. © 2017 American Institute of Chemical EngineersAIChE J, 64: 1651–1661, 2018
Cranial shape variation in adult howler monkeys (Alouatta seniculus)
Authors: Fiorenza Luca , Bruner Emiliano
Published: December 2017

Howler monkeys (genusAlouatta) display a distinctive cranial architecture characterized by airorhynchy(or retroflexion of the facial skeleton on the cranial base), a small braincase, and a posteriorly oriented foramen magnum. This configuration has been associated with distinct factors including a high folivory diet, locomotion, and the presence of a specialized vocal tract characterized by large hyoid bone. However, the morphological relationships between the facial and neurocranial blocks inAlouattahave been scarcely investigated. In this study we quantitatively analyzed the cranial shape variation inAlouatta seniculus, to evaluate possible influences and constraints in face and braincase associated with airorhynchy. We also considered the structural role of the pteric area within the cranial functional matrix. We applied landmark‐based analysis and multivariate statistics to 31 adult crania, computing shape analyses based on 3D coordinates registration as well as the analysis of the Euclidean distance matrix to investigate patterns of intraspecific morphological variability. Our results suggest that allometry is the main source of variation involved in shaping cranial morphology in howlers, influencing the degree of facial proportions and braincase flattening, and generating the main sexual differences. Larger individuals are characterized by a higher degree of airorhynchy, neurocranial flattening, and expansion of the zygomatic arch. Allometric variations influence the skull as a whole, without distinct patterns for face and braincase, which behave as an integrated morphological unit. A preliminary survey on the pteric pattern suggests that the morphology of this area may be the result of variations in the vertical growth rates between face and braincase. Future studies should be dedicated to the ontogenetic series and focus on airorhynchy in terms of differential growth among distinct cranial districts.
Solventless and Metal‐Free Synthesis of High‐Molecular‐Mass Polyaminoboranes from Diisopropylaminoborane and Primary Amines
Authors: De Albuquerque Pinheiro Carlos Antonio , Roiland Claire , Jehan Philippe , Alcaraz Gilles
Published: December 2017

The solventless reaction of diisopropylaminoborane with n‐butylamine, at room temperature, leads to a mixture of B(sp2)H‐, B(sp3)H2‐, and B(sp3)H3‐containing species. At low temperature, the reaction outcome is completely modified, thus leading selectively to the formation of high‐mass polybutylaminoborane. When extended to a variety of primary amines, under solventless conditions and at low temperature, this reaction provides a new, efficient, and direct metal‐free access to high‐molecular‐mass polyaminoboranes in good to high yields under mild reaction conditions.
Organocatalytic Enantioselective Higher‐Order Cycloadditions of In Situ Generated Amino Isobenzofulvenes
Authors: Donslund Bjarke S. , Monleón Alicia , Palazzo Teresa A. , Christensen Mette Louise , Dahlgaard Anne , Erickson Jeremy D. , Jørgensen Karl Anker
Published: December 2017

The [8+2] cycloaddition of indene‐2‐carbaldehydes and nitro olefins is described to provide benzonorbornene scaffolds in a highly peri‐, diastereo‐, and enantioselective fashion in the presence of a C2‐symmetric aminocatalyst. This reaction, which proceeds through a transient semi‐aromatic amino isobenzofulvene, represents the first example of catalytic formation and transformation of these species. Quantum chemical calculations suggest a kinetically controlled stepwise mechanism where the stereochemistry is determined in the first bond‐forming event. Beyond the useful [8+2] cycloadducts, [10+4] cycloadducts have been identified in silico as potential off‐pathway intermediates.
Hydrophilicity and Microsolvation of an Organic Molecule Resolved on the Sub‐molecular Level by Scanning Tunneling Microscopy
Authors: Lucht Karsten , Loose Dirk , Ruschmeier Maximilian , Strotkötter Valerie , Dyker Gerald , Morgenstern Karina
Published: December 2017

Low‐temperature scanning tunneling microscopy was used to follow the formation of a solvation shell around an adsorbed functionalized azo dye from the attachment of the first water molecule to a fully solvated molecule. Specific functional groups bind initially one water molecule each, which act as anchor points for additional water molecules. Further water attachment occurs in areas close to these functional groups even when the functional groups themselves are already saturated. In contrast, water molecules surround the hydrophobic parts of the molecule only when the two‐dimensional solvation shell closes around them. This study thus traces hydrophilic and hydrophobic properties of an organic molecule down to a sub‐molecular length scale.
Total Synthesis of Maoecrystal P: Application of a Strained Bicyclic Synthon
Authors: Su Fan , Lu Yandong , Kong Lingran , Liu Jingjing , Luo Tuoping
Published: December 2017

A new strategy was devised for the total synthesis of highly oxidized ent‐kauranoids. A highly regio‐ and diastereoselective intermolecular Diels–Alder cycloaddition involving a diene embedded in a substituted bicyclo[4.1.0] skeleton was used to assemble all carbon centers but C17 of the target molecule at an early stage of the synthesis. Subsequent synthetic steps, including redox manipulations, SmI2‐mediated cyclization, and isomerization reactions, afforded the antitumor natural product maoecrystal P.
Manganese(I)‐Catalyzed C−H (2‐Indolyl)methylation: Expedient Access to Diheteroarylmethanes
Authors: Lu Qingquan , Cembellín Sara , Greßies Steffen , Singha Santanu , Daniliuc Constantin G. , Glorius Frank
Published: December 2017

An unprecedented MnI‐catalyzed (2‐indolyl)methylation of heteroarenes is reported. This method makes use of an aromatizing cascade strategy to install a (2‐indolyl)methyl group into target molecules, thereby leading to the expedient synthesis of previously challenging and important unsymmetrical diheteroarylmethanes, in particular bis(2‐indolyl)methanes. The proposed cascade process comprises the reorganization of multiple bonds with controlled regioselectivity and high atom economy and can be performed on a gram‐scale. Furthermore, a metal‐free C−H propargylation is observed. The diverse application of this method is also demonstrated.
Temperature‐Responsive Luminescent Solar Concentrators: Tuning Energy Transfer in a Liquid Crystalline Matrix
Authors: Sol Jeroen A. H. P. , Dehm Volker , Hecht Reinhard , Würthner Frank , Schenning Albertus P. H. J. , Debije Michael G.
Published: December 2017

Temperature‐responsive luminescent solar concentrators (LSCs) have been fabricated in which the Förster resonance energy transfer (FRET) between a donor–acceptor pair in a liquid crystalline solvent can be tuned. At room temperatures, the perylene bisimide (PBI) acceptor is aggregated and FRET is inactive; while after heating to a temperature above the isotropic phase of the liquid crystal solvent, the acceptor PBI completely dissolves and FRET is activated. This unusual temperature control over FRET was used to design a color‐tunable LSC. The device has been shown to be highly stable towards consecutive heating and cooling cycles, making it an appealing device for harvesting otherwise unused solar energy.
Borazine‐CF3− Adducts for Rapid, Room Temperature, and Broad Scope Trifluoromethylation
Authors: Geri Jacob B. , Wade Wolfe Michael M. , Szymczak Nathaniel K.
Published: December 2017

A fluoroform‐derived borazine CF3− transfer reagent is used to effect rapid nucleophilic reactions in the absence of additives, within minutes at 25 °C. Inorganic electrophiles spanning seven groups of the periodic table can be trifluoromethylated in high yield, including transition metals used for catalytic trifluoromethylation. Organic electrophiles included (hetero)arenes, enabling C−H and C−X trifluoromethylation reactions. Mechanistic analysis supports a dissociative mechanism for CF3− transfer, and cation modification afforded a reagent with enhanced stability.
Stereoselective Total Synthesis of Hetisine‐type C20‐Diterpenoid Alkaloids: Spirasine IV and XI
Authors: Zhang Quanzheng , Zhang Zhongshan , Huang Zhong , Zhang Changhui , Xi Song , Zhang Min
Published: December 2017

The first total synthesis of the architecturally complex hetisine‐type heptacyclic C20‐diterpenoid alkaloids (±)‐spirasine IV and XI is reported. The A/F/G/C tetracyclic skeleton with the challenging N−C6 and C14−C20 linkages was efficiently constructed by an intramolecular azomethine‐ylide‐based 1,3‐dipolar cycloaddition with unusual regioselectivity. SmI2‐mediated free‐radical addition to the arene moiety without prior dearomatization and a stereoselective intramolecular aldol reaction further enabled rapid access to the hetisine core, providing a bicyclo[2.2.2]octane ring with a new oxygen substitution pattern.
Cooperative Formation of Long‐Range Ordering in Water Ad‐layers on Fe3O4(111) Surfaces
Authors: Mirabella Francesca , Zaki Eman , Ivars‐Barceló Francisco , Li Xiaoke , Paier Joachim , Sauer Joachim , Shaikhutdinov Shamil , Freund Hans‐Joachim
Published: December 2017

The initial stages of water adsorption on magnetite Fe3O4(111) surface and the atomic structure of the water/oxide interface remain controversial. Herein, we provide experimental results obtained by infrared reflection–absorption spectroscopy (IRAS) and temperature‐programmed desorption (TPD), corroborated by density functional theory (DFT) calculations showing that water readily dissociates on Fetet sites to form two hydroxo species. These act as an anchor for water molecules to form a dimer complex which self‐assembles into an ordered (2×2) structure. Water ad‐layer ordering is rationalized in terms of a cooperative effect induced by a hydrogen‐bonding network.
A Permselective CeOx Coating To Improve the Stability of Oxygen Evolution Electrocatalysts
Authors: Obata Keisuke , Takanabe Kazuhiro
Published: December 2017

Highly active NiFeOx electrocatalysts for the oxygen evolution reaction (OER) suffer gradual deactivation with time owing to the loss of Fe species from the active sites into solution during catalysis. The anodic deposition of a CeOx layer prevents the loss of such Fe species from the OER catalysts, achieving a highly stable performance. The CeOx layer does not affect the OER activity of the catalyst underneath but exhibits unique permselectivity, allowing the permeation of OH− and O2 through while preventing the diffusion of redox ions through the layer to function as a selective O2‐evolving electrode. The use of such a permselective protective layer provides a new strategy for improving the durability of electrocatalysts.
Heterogenized peroxopolyoxotungstate catalyst on the surface of clicked magnetite‐graphene oxide nanocomposite: Magnetically recoverable epoxidation catalyst
Authors: Masteri‐Farahani M. , Modarres M.
Published: December 2017

A new heterogeneous catalyst for the epoxidation of olefins was prepared by immobilization of peroxophosphotungstate anions on the surface of clicked magnetite‐graphene oxide as magnetically recoverable support. To prepare the heterogeneous catalyst, the clicked magnetite‐graphene oxide support was prepared by thiolene click reaction of thiol functionalized graphene oxide with vinyl modified magnetite nanoparticles. The tailored support was then modified with aminopropyl groups followed by electrostatic interaction with peroxophosphotungstate anions to achieve the desired heterogeneous catalyst. Characterization of the catalyst was performed by various physicochemical methods which confirmed the successful immobilization of peroxopolyoxotungstate species on the surface of clicked magnetite‐graphene oxide. Catalytic activity of the catalyst revealed its high catalytic activity and selectivity in the epoxidation of various olefins in the presence of H2O2 as green oxidant. This heterogeneous catalyst can be magnetically reused several times without significant loss of activity and selectivity.