bluuebunny/crossref_metadata_2025_split huggingface dataset:
Blue‐Emitting Iridium(III) Complexes for Light‐Emitting Electrochemical Cells: Advances, Challenges, and Future Prospects
Authors: Bai Rubing , Meng Xianwen , Wang Xiaoxiang , He Lei 
Published: January 2020

AbstractLight‐emitting electrochemical cells (LECs) are one of the most promising technologies for solid‐sate lighting. Among them, LECs based on phosphorescent iridium(III) complexes have attracted significant research interest in the past 15 years, because of their high efficiency and tunable emission color across the entire visible spectrum. To fabricate white LECs for lighting, high‐performance blue LECs are the first prerequisite. Huge efforts have been devoted to improving the performances of blue LECs based on iridium(III) complexes either by developing new blue‐emitting complexes or by engineering the devices. Nevertheless, blue LECs have still shown much lower performances (brightness, efficiency, stability, etc.) compared to the red, orange‐red, yellow, and green counterpart devices. In particular, a single blue LEC with satisfactory blue‐color purity, high efficiency, and high stability is still missing. Here, the advances in blue‐emitting iridium(III) complexes for LECs and the device engineering on LECs using the complexes are reported. The challenges ahead are discussed, and future prospects are outlined.
Toward Artificial Cells: Novel Advances in Energy Conversion and Cellular Motility
Authors: Jeong Sungwoo , Nguyen Huong Thanh , Kim Chang Ho , Ly Mai Nguyet , Shin Kwanwoo 
Published: January 2020

AbstractThe demand to discover every single cellular component has been continuously increasing along with the development of biological techniques. The bottom‐up approach to construct a cell‐mimicking system from well‐defined and tunable compositions is accelerating, with the ultimate goal of comprehending a biological cell. From among the available techniques, the artificial cell has been increasingly recognized as one of the most powerful tools for building a cell‐like system from scratch. This review summarizes the development of artificial cells, from a pure giant unilamellar vesicle (GUV) to a controllable, self‐fueled proteoliposome, both of which are highly compartmentalized. The basic components of an artificial cell, as well as the optimal conditions required for successful, reproducible GUV formation and protein reconstitution, are discussed. Most importantly, progress in studying the metabolic reactions in and the motility of a reconstituted artificial cell are the main focus of the review. The ability to perform a complicated reaction cascade in a controllable manner is highlighted as a promising perspective to obtaining an autonomous and movable GUV.
Mechanically Programmable Dip Molding of High Aspect Ratio Soft Actuator Arrays
Authors: Becker Kaitlyn P. , Chen Yufeng , Wood Robert J. 
Published: January 2020

AbstractThis work presents multiple methods of creating high aspect ratio fluidic soft actuators that can be formed individually or in large arrays via dip coating. Within this methodology, four strategies are provided to mechanically program the motion of these actuators, including the use of fiber inclusions, gravity, surface tension, and electric fields. The modular nature of this dip coating fabrication technique is inexpensive, easy to modify, and scalable. These techniques are used to demonstrate the fabrication of soft actuators with aspect ratios up to 200:1 and integrated arrays of up to 256 actuators. Furthermore, these methods have the potential to achieve higher aspect ratios and larger array sizes. Operating pressure, curvature, and curling strength tests reveal the design space in which fabrication parameters can be selected to tune the input and output parameters of soft bending actuators. An individual bending actuator made with these methods weighs between 0.15 and 0.5 g, can hold up to 2 N, and can be designed to work in groups to increase curling strength with distributed contact forces. Arrays of these actuators may be useful in atypical grasping and manipulation tasks, fluid manipulation, and locomotion.
A Universal Lab‐on‐Salt‐Particle Approach to 2D Single‐Layer Ordered Mesoporous Materials
Authors: Liu Liangliang , Yang Xuanyu , Xie Yujie , Liu Huan , Zhou Xinran , Xiao Xingyu , Ren Yuan , Ma Zhen , Cheng Xiaowei , Deng Yonghui , Zhao Dongyuan 
Published: January 2020

AbstractThe advantages of existing ordered mesoporous materials have not yet been fully realized, due to their limited accessibility of in‐pore surface and long mass‐diffusion length. A general, controllable, and scalable synthesis of a family of two‐dimensional (2D) single‐layer ordered mesoporous materials (SOMMs) with completely exposed mesopore channels, significantly improved mass diffusion, and diverse framework composition is reported here. The SOMMs are synthesized via a surface‐limited cooperative assembly (SLCA) on water‐removable substrates of inorganic salts (e.g., NaCl), combined with vacuum filtration. As a proof of concept, the obtained CeO2‐based SOMMs show superior catalytic performance in CO oxidation with high conversion efficiency, ≈33 times higher than that of conventional bulk mesoporous CeO2. This SLCA is a promising approach for developing next‐generation porous materials for various applications.
Variable‐Temperature Electron Transport and Dipole Polarization Turning Flexible Multifunctional Microsensor beyond Electrical and Optical Energy
Authors: Cao Mao‐Sheng , Wang Xi‐Xi , Zhang Min , Cao Wen‐Qiang , Fang Xiao‐Yong , Yuan Jie 
Published: January 2020

AbstractHumans are undergoing a fateful transformation focusing on artificial intelligence, quantum information technology, virtual reality, etc., which is inseparable from intelligent nano–micro devices. However, the booming of “Big Data” brings about an even greater challenge by growing electromagnetic radiation. Herein, an innovative flexible multifunctional microsensor is proposed, opening up a new horizon for intelligent devices. It integrates “non‐crosstalk” multiple perception and green electromagnetic interference shielding only in one pixel, with satisfactory sensitivity and fast information feedback. Importantly, beneficial by deep insight into the variable‐temperature electromagnetic response, the microsensor tactfully transforms the urgent threat of electromagnetic radiation into “wealth,” further integrating self‐power. This result will refresh researchers' realization of next‐generation devices, ushering in a new direction for aerospace engineering, remote sensing, communications, medical treatment, biomimetic robot, prosthetics, etc.
Engineering Oxygen Vacancies in a Polysulfide‐Blocking Layer with Enhanced Catalytic Ability
Authors: Li Zhaohuai , Zhou Cheng , Hua Junhui , Hong Xufeng , Sun Congli , Li Hai‐Wen , Xu Xu , Mai Liqiang 
Published: January 2020

AbstractThe practical application of the lithium–sulfur (Li–S) battery is seriously restricted by its shuttle effect, low conductivity, and low sulfur loading. Herein, first‐principles calculations are conducted to verify that the introduction of oxygen vacancies in TiO2 not only enhances polysulfide adsorption but also greatly improves the catalytic ability and both the ion and electron conductivities. A commercial polypropylene (PP) separator decorated with TiO2 nanosheets with oxygen vacancies (OVs‐TiO2@PP) is fabricated as a strong polysulfide barrier for the Li–S battery. The thickness of the OVs‐TiO2 modification layer is only 500 nm with a low areal mass of around 0.12 mg cm−2, which enhances the fast lithium‐ion penetration and the high energy density of the whole cell. As a result, the cell with the OVs‐TiO2@PP separator exhibits a stable electrochemical behavior at 2.0 C over 500 cycles, even under a high sulfur loading of 7.1 mg cm−2, and an areal capacity of 5.83 mAh cm−2 remains after 100 cycles. The proposed strategy of engineering oxygen vacancies is expected to have wide applications in Li–S batteries.
Shine Bright Like a Diamond: New Light on an Old Polymeric Semiconductor
Authors: Giusto Paolo , Cruz Daniel , Heil Tobias , Arazoe Hiroki , Lova Paola , Aida Takuzo , Comoretto Davide , Patrini Maddalena , Antonietti Markus 
Published: January 2020

AbstractBrilliance usually refers to the light reflected by the facets of a gemstone such as diamond due to its high refractive index. Nowadays, high‐refractive‐index materials find application in many optical and photonic devices and are mostly of inorganic nature. However, these materials are usually obtained by toxic or expensive production processes. Herein, the synthesis of a thin‐film organic semiconductor, namely, polymeric carbon nitride, by thermal chemical vapor deposition is presented. Among polymers, this organic material combines the highest intrinsic refractive index reported so far with high transparency in the visible spectrum, even reaching the range of diamond. Eventually, the herein presented deposition of high quality thin films and their optical characteristics open the way for numerous new applications and devices in optics, photonics, and beyond based on organic materials.
A Removable Insertion Shuttle for Ultraflexible Neural Probe Implantation with Stable Chronic Brain Electrophysiological Recording
Authors: Zhang Shun , Wang Chengjun , Gao Huan , Yu Chaonan , Yan Qinghao , Lu Yuchen , Tao Zhehao , Linghu Changhong , Chen Zhou , Xu Kedi , Song Jizhou 
Published: January 2020

AbstractUltraflexible neural probe is an ideal tool for brain research, which can reduce the mechanical interfacial mismatch between electrodes and brain tissue and can thus reduce the tissue's inflammation and extend the electrodes' service life. However, the low stiffness of ultraflexible neural probe makes it susceptible to bending and buckling during insertion into brain. Here, a simple yet robust design of removable insertion shuttle consisting of a steel needle with a dissolvable spheroid micropost is reported for ultraflexible neural probe implantation. The dissolvable spheroid micropost of insertion shuttle is fabricated by the simple dip‐coating process based on the competition and balance between the surface tension and gravity. A temporary engaging mechanism enabled by the micropost engaged into the via hole on the tip of ultraflexible neural probe is adopted to enable an easy and quick implantation. Experimental studies reveal the fundamental aspects of the design of removable insertion shuttle and the operation of implantation. In vivo implantation of ultraflexible neural probes into rat's brain illustrates the unusual capabilities of removable insertion shuttle with the accurate positioning of probe at desired depth and the stable chronic brain electrophysiological recording, which show great potential in both basic neuroscience and clinical applications.
Flexible Difunctional (Pressure and Light) Sensors Based on ZnO Nanowires/Graphene Heterostructures
Authors: Wang Yuan , Zhu Laipan , Du Cuifeng 
Published: January 2020

AbstractThe piezotronic and piezo‐phototronic effects have been extensively utilized in the third‐generation semiconductors, such as ZnO, CdS, and GaN, to enhance the performances of electronic and optoelectronic devices. Using the principle of these two effects, here, a flexible difunctional sensor based on graphene/ZnO nanowire array, which can be used to detect vertical pressure as well as ultraviolet light power, is presented. This device shows a linear response to vertical pressures by measuring the change of current, and a pressure sensitivity of 1.7 nA kPa−1 for smaller pressures. It can also be used to measure the bending strain applied on the substrate. A uniform photoresponsivity of 3.5 µA W−1 for a 325 nm laser excitation is obtained, and the response speeds for light on‐ and off‐states are 28 and 25 ms, respectively, revealing excellent photoelectric property of this device. These nanowires/graphene heterostructures are flexible with low cost and easy fabrication processes, making it potential in applications of wearable electronic and optoelectronic devices.
Ultrathin Scattering Spin Filter and Magnetic Tunnel Junction Implemented by Ferromagnetic 2D van der Waals Material
Authors: Lin Zheng‐Zhe , Chen Xi 
Published: January 2020

AbstractEmerging research in 2D materials has promoted the development of nanoelectronics. Ferromagnetic van der Waals (vdW) layered materials can be utilized to implement ultrathin spintronic devices with new functionalities. The theoretical investigation of 2D vdW scattering spin filters and magnetic tunnel junctions consisting of atomically thin Fe3GeTe2 (FGT) are reported. By the nonequilibrium Green's function technique, the spin polarization of ballistic transport through single‐/double‐layer FGT sandwiched between two Cu electrodes is predicted to be 53/85%. In ultrathin FGT‐hBN‐FGT heterostructures, remarkable magnetoresistance is observed, in which maximum (minimum) resistance occurs when the magnetization of two FGT layers is parallel (antiparallel) to each other. For heterostructures consisting of single‐/double‐layer FGT, the magnetoresistance reaches 183/252% at zero‐bias limit. The parallel state of a FGT magnetic tunnel junction exhibits spin polarization larger than 75%. These results suggest the application of magnetic vdW layered materials in ultrathin spintronics.
Piezoelectric Response of Polycrystalline Silicon‐Doped Hafnium Oxide Thin Films Determined by Rapid Temperature Cycles
Authors: Mart Clemens , Kämpfe Thomas , Hoffmann Raik , Eßlinger Sophia , Kirbach Sven , Kühnel Kati , Czernohorsky Malte , Eng Lukas M. , Weinreich Wenke 
Published: January 2020

AbstractThe in‐plane piezoelectric response of 20 nm thick Si‐doped HfO2 is examined by exploiting thermal expansion of the substrate upon rapid temperature cycling. The sample is heated locally by a deposited metal film, and the subsequently registered pyroelectric current is found to be frequency dependent in the observed range of 5 Hz to 35 kHz. While the intrinsic response remains constant, the secondary contribution can be switched off in the high‐frequency limit due to substrate clamping. As this secondary response is generated by thermal expansion and the piezoelectric effect, this allows for extraction of the corresponding in‐plane response. By comparing pyroelectric measurements in low‐ and high‐frequency limits, a piezoelectric coefficient d31 of −11.5 pm V −1 is obtained, which is more than five times larger than that of AlN. The magnitude of piezoelectric response increases upon electric field cycling, which is associated with a transition from antiferroelectric‐like behavior to a purely ferroelectric polarization hysteresis. The hafnium oxide material system is proposed as a promising candidate for future CMOS compatible piezoelectric micro‐ and nano‐electromechanical systems (MEMS and NEMS).
Interplay Among Thermoelectric Properties, Atmospheric Stability, and Electronic Structures in Solution‐Deposited Thin Films of P(NaX[Niett])
Authors: Hwang Sunbin , Potscavage William J. , Kim Tae‐Wook , Adachi Chihaya 
Published: January 2020

AbstractRecent progress in organic thermoelectric generators has resulted in high performance through chemical control of the redox levels of organic semiconductors, but the scarcity of good candidates for soluble organic n‐type materials limits the use of π‐leg structures consisting of complementary elements of p‐ and n‐type materials because of unbalanced transport coefficients that lead to power losses. A sol–gel technique with oxidation is demonstrated to be effective for the fabrication of smooth films of poly(nickel 1,1,2,2‐ethenetetrathiolate), P(MX[Niett]), which is known as an insoluble material. By controlling the annealing temperature, a maximum n‐type power factor of 10.1 μW m−1 K−2 at 100 °C (Seebeck coefficient of −35.4 μV K−1 and electrical conductivity of 80.3 S cm−1) is demonstrated. Chemical and electronic structures of P(MX[Niett]) thin films are explored based on changes in optical absorption, ultraviolet, and X‐ray photoelectron spectroscopies to understand the origin of the high atmospheric stability. Analysis indicates that the stability arises from electronic states of the doped state that satisfy a balance with the redox potential of the air components and that stability under repeated redox reactions is an important factor for obtaining the n‐type organic thermoelectric materials that are highly stable in air.
Critical Role of Polymer Aggregation and Miscibility in Nonfullerene‐Based Organic Photovoltaics
Authors: Yi Xueping , Peng Zhengxing , Xu Bing , Seyitliyev Dovletgeldi , Ho Carr Hoi Yi , Danilov Evgeny O. , Kim Taesoo , Reynolds John R. , Amassian Aram , Gundogdu Kenan , Ade Harald , So Franky 
Published: January 2020

AbstractUnderstanding the correlation between polymer aggregation, miscibility, and device performance is important to establish a set of chemistry design rules for donor polymers with nonfullerene acceptors (NFAs). Employing a donor polymer with strong temperature‐dependent aggregation, namely PffBT4T‐2OD [poly[(5,6‐difluoro‐2,1,3‐benzothiadiazol‐4,7‐diyl)‐alt‐(3,3″′‐di(2‐octyldodecyl)‐2,2′;5′,2″;5″,2″′‐quaterthiophen‐5,5‐diyl)], also known as PCE‐11 as a base polymer, five copolymer derivatives having a different thiophene linker composition are blended with the common NFA O‐IDTBR to investigate their photovoltaic performance. While the donor polymers have similar optoelectronic properties, it is found that the device power conversion efficiency changes drastically from 1.8% to 8.7% as a function of thiophene content in the donor polymer. Results of structural characterization show that polymer aggregation and miscibility with O‐IDTBR are a strong function of the chemical composition, leading to different donor–acceptor blend morphology. Polymers having a strong tendency to aggregate are found to undergo fast aggregation prior to liquid–liquid phase separation and have a higher miscibility with NFA. These properties result in smaller mixed donor–acceptor domains, stronger PL quenching, and more efficient exciton dissociation in the resulting cells. This work indicates the importance of both polymer aggregation and donor–acceptor interaction on the formation of bulk heterojunctions in polymer:NFA blends.
A Critical Review of Machine Learning of Energy Materials
Authors: Chen Chi , Zuo Yunxing , Ye Weike , Li Xiangguo , Deng Zhi , Ong Shyue Ping 
Published: January 2020

AbstractMachine learning (ML) is rapidly revolutionizing many fields and is starting to change landscapes for physics and chemistry. With its ability to solve complex tasks autonomously, ML is being exploited as a radically new way to help find material correlations, understand materials chemistry, and accelerate the discovery of materials. Here, an in‐depth review of the application of ML to energy materials, including rechargeable alkali‐ion batteries, photovoltaics, catalysts, thermoelectrics, piezoelectrics, and superconductors, is presented. A conceptual framework is first provided for ML in materials science, with a broad overview of different ML techniques as well as best practices. This is followed by a critical discussion of how ML is applied in energy materials. This review is concluded with the perspectives on major challenges and opportunities in this exciting field.
Ultraviolet Photoemission Spectroscopy and Kelvin Probe Measurements on Metal Halide Perovskites: Advantages and Pitfalls
Authors: Zhang Fengyu , Silver Scott H. , Noel Nakita K. , Ullrich Florian , Rand Barry P. , Kahn Antoine 
Published: January 2020

AbstractIn this essay, a case study is presented on the electronic structure of several metal halide perovskites (MHP) using Kelvin probe (KP)‐based surface photovoltage (SPV) measurements and ultraviolet photoemission spectroscopy (UPS) to demonstrate the advantages, but also the pitfalls, of using these techniques to characterize the surfaces of these materials. The first part addresses the loss of halide species from perovskite surfaces upon supragap illumination in vacuum. This has the potential to cause both a long‐term alteration of the sample work function and a modification of the KP tip during SPV measurements. If undetected, this leads to a misinterpretation of the MHP surface potential. The second part illustrates the difficulties in determining the valence band maximum (VBM) of MHP surfaces with UPS and stresses the importance of taking into account the low density of states at the VBM edge. Given this circumstance, specific care must be taken to eliminate measurement artifacts in order to ascertain the presence or absence of low densities of electronic gap states above the VBM. This essay also highlights issues such as film degradation, nonequilibrium situations (e.g., SPV), and satellite emissions, which occur during photoemission spectroscopy.
Eliminating Transition Metal Migration and Anionic Redox to Understand Voltage Hysteresis of Lithium‐Rich Layered Oxides
Authors: Han Miao , Jiao Junyu , Liu Zepeng , Shen Xi , Zhang Qinghua , Lin Hong‐Ji , Chen Chien‐Te , Kong Qingyu , Pang Wei Kong , Guo Zaiping , Yu Richeng , Gu Lin , Hu Zhiwei , Wang Zhaoxiang , Chen Liquan 
Published: January 2020

AbstractLithium‐rich layered oxides are promising candidate cathode materials for the Li‐ion batteries with energy densities above 300 Wh kg−1. However, issues such as the voltage hysteresis and decay hinder their commercial applications. Due to the entanglement of the transition metal (TM) migration and the anionic redox upon lithium extraction at high potentials, it is difficult to recognize the origin of these issues in conventional Li‐rich layered oxides. Herein, Li2MoO3 is chosen since prototype material to uncover the reason for the voltage hysteresis as the TM migration and anionic redox can be eliminated below 3.6 V versus Li+/Li in this material. On the basis of comprehensive investigations by neutron powder diffraction, scanning transmission electron microscopy, synchrotron X‐ray absorption spectroscopy, and density functional theory calculations, it is clarified that the ordering–disordering transformation of the Mo3O13 clusters induced by the intralayer Mo migration is responsible for the voltage hysteresis in the first cycle; the hysteresis can take place even without the anionic redox or the interlayer Mo migration. A similar suggestion is drawn for its iso‐structured Li2RuO3 (C2/c). These findings are useful for understanding of the voltage hysteresis in other complicated Li‐rich layered oxides.
Engineering Electronic Structure of Stannous Sulfide by Amino‐Functionalized Carbon: Toward Efficient Electrocatalytic Reduction of CO2 to Formate
Authors: Chen Zhipeng , Zhang Xinxin , Jiao Mingyang , Mou Kaiwen , Zhang Xiangping , Liu Licheng 
Published: January 2020

AbstractEngineering electronic structure to enhance the binding energies of reaction intermediates in order to achieve a high partial current density can lead to increased yield of target products. Herein, amino‐functionalized carbon is used to regulate the electronic structure of tin‐based catalysts to enhance activity of CO2 electroreduction. The hollow nanotubes composed of SnS (stannous sulfide) nanosheets are modified with amino‐functionalized carbon layers, achieving a highest formate Faraday efficiency of 92.6% and a remarkable formate partial current density of 41.1 mA cm−2 (a total current density of 52.1 mA cm−2) at a moderate overpotential of 0.9 V versus reversible hydrogen electrode, as well as a good stability. Density functional theory calculations demonstrate that the superior activity is attributed to the synergistic effect among SnS and Aminated‐C in increasing the adsorption energies of the key intermediates and accelerating the charge transfer rate.