bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physics and Optoelectronic Simulation of Photodetectors Based on 2D Materials
Authors: Cao Guoyang , An Yidan , Bao Qiaoliang , Li Xiaofeng 
Published: May 2019

Abstract2D‐material‐based photodetectors (2DMPDs) have attracted broad interest due to their many unique benefits (e.g., their giant photoresponsivity). However, a thorough device‐level simulation, which takes into account optical absorption, electrical transportation, and semiconductor material properties, is still challenging. This study reports the realization of a comprehensive optoelectronic simulation of 2DMPDs in multidimensional and multiphysics domains. This work begins with a simulation of conventional monolayer photoresistor detectors by introducing basic theories and simulation technologies. In particular, the trap effect, which is highly important for regulating the photoresponse of 2D devices, is successfully introduced into the simulation so that very good agreement between the simulation and an experiment is realized. The simulation is extended to popular monolayer phototransistors so that precise quantitative evaluations of the optoelectronic device performance, such as the output characteristics, transfer properties, responsivity, response time, and detectivity, become very convenient. Furthermore, a time‐domain device simulation is implemented, which allows to study the modulation characteristics of 2DMPDs. The device‐level simulation provides a useful platform for studying and optimally designing advanced 2DMPDs. For example, this simulation is convenient for studying the balance between photoresponsivity and response time in 2DMPDs.
H‐/dT‐MoS2‐on‐MXene Heterostructures as Promising 2D Anode Materials for Lithium‐Ion Batteries: Insights from First Principles
Authors: Shao Yangfan , Gong Penglai , Pan Hui , Shi Xingqiang 
Published: May 2019

AbstractExperimental synthesis of two‐dimensional MoS2‐on‐MXene heterostructures and phase control of MoS2 have been demonstrated recently. Here, the electronic, electrochemical, mechanical properties, and structural morphology of MoS2@Ti2C and MoS2@Ti2CO2 heterostructures as anode materials for lithium‐ion batteries are systematically investigated by taking advantages of van der Waals corrected spin‐polarized density functional theory to give atomistic insights. The results herein demonstrate that, for the MoS2@Ti2CO2 heterostructure, MoS2 polymorph drastically affects the electronic structure and lithium (Li) diffusion at the interface. Li diffusion barrier at the interface of dT‐MoS2@Ti2CO2 along zigzag direction (0.15 eV) is much smaller than that of H‐MoS2@Ti2CO2 (0.67 eV). For the MoS2@Ti2C heterostructure, however, the Li diffusion behavior and electronic structure are relatively insensitive to MoS2 morphology. Especially, the MoS2@Ti2C heterostructures shows ultralow diffusion barrier, high charge–discharge rate, very low open‐circuit voltage (0.62–0.25 V), and high mechanical flexibility. These results suggest that MoS2@MXene heterostructures are promising anode materials for lithium‐ion batteries.
Threshold Voltage Modulation of a Graphene–ZnO Barristor Using a Polymer Doping Process
Authors: Kim So‐Young , Hwang Jeongwoon , Kim Yun Ji , Hwang Hyeon Jun , Son Myungwoo , Revannath Nikam , Ham Moon‐Ho , Cho Kyeongjae , Lee Byoung Hun 
Published: May 2019

AbstractA method to modulate the threshold voltage of a graphene–ZnO barristor is investigated. Two types of polymers, polyethyleneimine (as an n‐type dopant) and poly (acrylic acid) (as a p‐type dopant), are used to pre‐set the initial Fermi level of the graphene. The threshold voltage of the graphene barristor can be modulated between −2.0 V (n‐type graphene) and 1.2 V (p‐type graphene) while modulating the Fermi level of the graphene by 120 meV. This process provides a scalable and facile method to adjust the threshold voltage of graphene–semiconductor junction‐based devices, which is a crucial function required to implement graphene‐based electronic devices in integrated circuits.
Conducting‐Polymer Bolometers for Low‐Cost IR‐Detection Systems
Authors: Håkansson Anna , Shahi Maryam , Brill Joseph W. , Fabiano Simone , Crispin Xavier 
Published: May 2019

AbstractSemiconducting polymers are promising materials for manufacturing optoelectronic devices, such as large‐area solar cells or small light‐emitting diodes, through the use of printing technologies. In their oxidized form, π‐conjugated polymers become good electrical conductors and their optical absorption shifts to the infrared region. It is demonstrated that conducting polymers can be integrated in bolometers for IR detection. A bolometer is a thermally isolated thin device that absorbs IR radiation and translates a temperature change into a change in electrical resistance. While commercial bolometers are usually made of complex architectures comprising several materials (that is, an IR absorbing layer, a conducting layer, and a thermally insulating layer), the first polymer bolometer is demonstrated with a freestanding layer of poly(3,4‐ethylene‐dioxythiophene) having high IR absorption, low thermal conductivity, and good thermistor action in one single layer. The solution processability of conducting polymers, their compatibility with high‐resolution printing technologies, and their unique combination of optoelectronic properties can lead to a breakthrough for low‐cost uncooled IR cameras, which are in high demand for security and safety applications.
Surface Catalytic Modification of Conjugated Polymer on Low‐Cost Bottom Contact for Improved Injection Efficiency of Organic Transistors
Authors: Chen Xiaosong , Yi Kongyang , Zhang Wenjing , Wei Dacheng , Liu Yunqi 
Published: May 2019

AbstractTheir mismatched energy alignment with organic semiconductors limits the application of low‐cost metals in organic electronics. A novel surface catalytic low‐temperature chemical vapor deposition (CVD) based on the Ullmann reaction is applied to selectively modify patterned Ag/Cu electrodes. The work functions of Ag and Cu are tuned from 4.3 and 4.5 eV to 4.8 and 4.9 eV, respectively, after modification with conjugated polymers. Owing to the change in work function and pentacene morphology, the contact resistance decreases by several orders of magnitude compared with that of devices with pristine Ag or Cu electrodes, and the correspond mobilities of pentacene bottom‐contact field effect transistors increase to 0.66 cm2 V−1 s−1 (Ag) and 0.64 cm2 V−1 s−1 (Cu). This mobility is one of the highest values demonstrated with pentacene organic field‐effect transistors with Cu or Ag electrodes. This simple, clean, and low‐temperature modification method paves the way for the application of low‐cost metals in organic electronics.
Flexible Magnetoelectrical Devices with Intrinsic Magnetism and Electrical Conductivity
Authors: Dai Wenting , Xu Hang , Zhang Chaonan , Li Ya , Pan Huizhuo , Wang Hanjie , Wei Gaofeng , Huang Xian 
Published: May 2019

AbstractDevelopment of flexible magnetoelectrical (ME) electronics has encountered huge challenges due to mechanical mismatch, environmental instability, and the weak electrical conductivity of extremely hard neodymium iron boron materials. A series of techniques involving mechanical milling, core–shell structure synthesis, printing electronics, and photonic sintering are developed to achieve composite materials and flexible ME devices demonstrated as sensors, circuit components, printed circuit boards circuits, and interfaces. These devices, which are mechanically compatible with the demands of flexible electronics, offer both excellent magnetism (coercivity >2800 Oe) and electrical conductivity (>41743 S m−1), allowing novel functions and simplified design that benefit from the coexistence and interaction of magnetic and electrical fields. These materials, devices, and process techniques serve as additions to the existing flexible‐electronics framework, and may also inspire development of more innovative ME devices and applications in biology, healthcare, industry, and consumer electronics.
Tailoring the Local Conductivity of TiO2 by X‐Ray Nanobeam Irradiation
Authors: Mino Lorenzo , Bonino Valentina , Picollo Federico , Fretto Matteo , Agostino Angelo , Truccato Marco 
Published: May 2019

AbstractIt is well known that intense synchrotron beams can alter the state of materials, but this effect is generally considered undesired radiation damage. The effect of local irradiation of TiO2 rutile single crystals is investigated by a 56 × 57 nm2 synchrotron X‐ray nanobeam at 17.4 keV. Aside from a transient increase of conductivity due to a photovoltaic‐like process, a nonvolatile localized change of resistance by about 4 orders of magnitude is measured after X‐ray exposure. This effect can be ascribed to the local generation of oxygen vacancies by the X‐ray nanoprobe, which are subsequently ordered by the electric field applied during the acquisition of I–V curves. These results demonstrate that intense synchrotron beams can create oxygen vacancies in materials with tightly bound oxygen atoms, highlighting that X‐ray nanoprobes could become an effective tool for oxide nanofabrication, able to locally tune the material resistivity. For instance, since the localized presence and migration of oxygen vacancies is an essential requisite for redox‐based memristive devices, the possibility to locally induce oxygen vacancies could represent a novel tool for the production of oxide‐based memristive devices, replacing the problematic electroforming step.
Design of Mixed‐Cation Tri‐Layered Pb‐Free Halide Perovskites for Optoelectronic Applications
Authors: Liu Zhun , Zhao Xingang , Zunger Alex , Zhang Lijun 
Published: May 2019

AbstractTo eliminate the toxic Pb2+ cation in hybrid halide perovskites, M′3+ cations of Bi/Sb‐based layered halide perovskites are being increasingly investigated for optoelectronic applications. However, such M′3+ trivalent cations constrain the face‐sharing bioctahedral or the bi‐layered perovskites required to meet the charge neutrality condition. This usually gives rise to oversized indirect bandgaps and inferior carrier transport. Recent experiment suggested a mixed‐cation tri‐layered halide perovskite can be obtained by sandwiching a [Cu2+X6]4− layer between Sb3+ perovskite bilayers along the polar [111] planes with cation ordering. A material design of mixed‐cation <111>‐oriented tri‐layered Pb‐free halide perovskite A4MM′2X12 is studied by a computational screening of various combinations of M2+ cations (e.g., Zn2+, Sn2+) and M′3+ cations (e.g., Bi3+, Sb3+). The thermodynamic stability of the candidate materials is systemically evaluated with respect to potential decomposition pathways and a series of stable compounds is synthesized. These results further indicate the chemical trend of electronic structure and how octahedral tilting coupling with charge ordering affects electronic properties. A protocol for engineering A4MM′2X12 perovskites with optimized structures and electronic properties by exploiting octahedral tilting coupling with charge ordering in the polar <111> layered perovskites is established.
Nonvolatile Electric Control of Exchange Bias by a Redox Transformation of the Ferromagnetic Layer
Authors: Zehner Jonas , Huhnstock Rico , Oswald Steffen , Wolff Ulrike , Soldatov Ivan , Ehresmann Arno , Nielsch Kornelius , Holzinger Dennis , Leistner Karin 
Published: May 2019

AbstractElectric manipulation of exchange bias (EB) systems is highly attractive for the development of modern spintronic and magnetophoretic devices. To date, electric control of the EB has mainly been based on multiferroic or resistive switching behavior in specific antiferromagnets, which limits the material choice and accessible EB states. In addition, the effects are mostly volatile, requiring constant voltage application. The continuous and nonvolatile tuning of the EB via electrochemical manipulation of the ferromagnetic layer is presented. In FeOx/Fe/IrMn systems, large changes in the EB field of fully shifted magnetization curves are achieved at low voltage (<1 V) and room temperature. A ferromagnetic‐layer thickness change resulting from the electrochemical reduction of iron oxide to iron is proposed as the underlying mechanism and is consistent with a simple model for the EB and surface analysis. Nonvolatility is achieved as the reduction proceeds at the buried FeOx/Fe interface, leaving the remaining oxide as a protective layer. A lateral voltage‐controlled patterning of the EB fields and magnetic domain state is demonstrated. This versatile redox‐based electric control of the EB paves a new route for the design of EB systems in general and for the development of future electrically controlled EB devices.
Conductive, Solution‐Processed Dioxythiophene Copolymers for Thermoelectric and Transparent Electrode Applications
Authors: Ponder James F. , Menon Akanksha K. , Dasari Raghunath R. , Pittelli Sandra L. , Thorley Karl J. , Yee Shannon K. , Marder Seth R. , Reynolds John R. 
Published: May 2019

AbstractConjugated polymers with high electrical conductivities are attractive for applications in capacitors, biosensors, organic thermoelectrics, and transparent electrodes. Here, a series of solution processable dioxythiophene copolymers based on 3,4‐propylenedioxythiophene (ProDOT) and 3,4‐ethylenedioxythiophene (EDOT) is investigated as thermoelectric and transparent electrode materials. Through structural manipulation of the polymer repeat unit, the conductivity of the polymers upon oxidative solution doping is tuned from 1 × 10−3 to 3 S cm−1, with a polymer consisting of a solubilizing alkylated ProDOT unit and an electron‐rich biEDOT unit (referred to as PE2) showing the highest electrical conductivity. Optimization of the film casting method and screening of dopants result in AgPF6‐doped PE2 achieving a high electrical conductivity of over 250 S cm−1 and a thermoelectric power factor of 7 μW m−1 K−2. Oxidized spray cast films of PE2 are also assessed as a transparent electrode material for use with another electrochromic polymer. This bilayer shows reversible electrochemical switching from a colored charge‐neutral state to a highly transmissive color‐neutral, oxidized state. These results demonstrate that dioxythiophene‐based copolymers are a promising class of materials, with ProDOT–biEDOT serving as a soluble analog to the well‐studied PEDOT as a p‐type thermoelectric and electrode material.
Strategies Toward Stable Nonaqueous Alkali Metal–O2 Batteries
Authors: Zhang Wang , Huang Yang , Liu Ying , Wang Lei , Chou Shulei , Liu Huakun 
Published: May 2019

AbstractAlkali metal–O2 batteries, by coupling high‐capacity alkali metal anodes with gaseous oxygen, possess extremely high gravimetric energy density that is comparable to gasoline and are potential energy storage technologies beyond lithium–ion batteries. The development of alkali metal–O2 batteries has achieved great progress in recent years, from materials to prototype devices and on fundamental mechanisms. The stability of alkali metal–O2 batteries is still poor, however, leading to a huge gap between laboratory research and commercial applications. A series of parasitic reactions result in the instability, which occur during electrochemical discharging and charging. The ubiquitous active oxygen species attack both the organic electrolyte and the carbon cathode, triggering various parasitic reactions. Meanwhile, dendrite growth and volume expansion upon repeated plating/stripping and O2 crossover severely limit the reversibility of alkali metal anodes. Here, an overview of the strategies against these issues is given to improve the stability of nonaqueous alkali metal–O2 batteries, which is discussed from three aspects: air cathodes, alkali metal anodes, and aprotic electrolytes. Furthermore, perspectives for future research of stable alkali metal–O2 batteries are outlined.
First evidence of a therapeutic effect of miransertib in a teenager with Proteus syndrome and ovarian carcinoma
Authors: Leoni Chiara , Gullo Giuseppe , Resta Nicoletta , Fagotti Anna , Onesimo Roberta , Schwartz Brian , Kazakin Julia , Abbadessa Giovanni , Crown John , Collins Conor D. , Ranieri Carlotta , Scambia Giovanni , Zampino Giuseppe 
Published: May 2019

AbstractProteus syndrome (PS) is an ultra‐rare disease characterized by progressive, disproportionate, segmental overgrowth caused by a somatic gain‐of‐function mutation p.Glu17Lys in the oncogene AKT1. The disease has high morbidity and mortality rates due to the increased risk for patients to develop cancer and progressive overgrowth. A teenage patient with severe PS phenotype developed a pelvic recurrence of low‐grade serous ovarian carcinoma (LGSOC). Taking into consideration, recent results of the use of AKT inhibitors both in PS and AKT‐mutant cancers, we treated the patient on a compassionate basis, with miransertib (ARQ 092), a potent, selective, allosteric AKT inhibitor. Targeted deep sequencing assay of PI3K/AKT pathway genes of the affected overgrowth lesion (cerebriform connective tissue nevus) and the tumor tissues detected the same activating AKT1 mutation in both. Treatment with miransertib led to a complete remission of the cancer and a significant improvement in the patients' everyday life. The treatment is still ongoing at 22 months. This is the first report showing the therapeutic effects of an AKT inhibitor on both benign and malignant tissues that harbor the same pathogenic AKT1 mutation. The present article showed that personalized medicine is feasible in ultra‐rare diseases.
Preparation of a Chiral Building Block by an Organocatalytic Asymmetric Intramolecular Michael Reaction
Authors: Sato Yusuke , Hosoya Yosuke , Kobayashi Ikumi , Adachi Kyohei , Nakada Masahisa 
Published: May 2019

AbstractThe preparation of a chiral building block, including a stereodiad consisting of two tertiary stereogenic centers, by a highly enantioselective organocatalytic intramolecular Michael reaction is described. The use of a chiral secondary‐amine‐bearing thiourea substituted with a para‐nitrophenyl group in the presence of benzoic acid is key to preparing the chiral building block in high yield and excellent enantioselectivity. The prepared chiral building block has both aldehyde and nitro groups, allowing a variety of functional‐group transformations necessary for the total synthesis of atisane‐type terpenoids.
Substantially enhancing the catalytic performance of bis(imino)pyridylcobaltous chloride pre‐catalysts adorned with benzhydryl and nitro groups for ethylene polymerization
Authors: Mahmood Qaiser , Ma Yanping , Hao Xiang , Sun Wen‐Hua 
Published: May 2019

Variations in the ligand structure of homogeneous late transition metal catalysts through judicious choice and location of substituent is the foremost strategy in improving their catalytic performance for ethylene polymerization. In this contribution, symmetrical and unsymmetrical bis(imino)pyridylcobaltous chloride complexes adorned with nitro and benzhydryl groups {2‐[1‐(2,6‐dibenzhydryl‐4‐nitrophenylimino)ethyl]‐6‐[1‐(alkylphenylimino)ethyl]pyridylcobaltous chloride (alkyl: R1 = Me and R2 = H, Co1; R1 = Et and R2 = H, Co2; R1 = iPr and R2 = H, Co3; R1 and R2 = Me, Co4; R1 = Et and R2 = Me, Co5; R1 = benzhydryl and R2 = NO2, Co6)} have been prepared and applied as catalysts for ethylene polymerization. The molecular structure of Co1 and Co2 revealed the unequal steric protection of the cobalt center induced by bis(imino)pyridine chelate. In the presence of methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) activators at different ethylene feeding rates (1 and 10 atm), catalysts Co1–Co5 displayed high activities at 10 atm ethylene and produced strictly linear polyethylene (PE) with high molecular weight, Co2/MMAO being the most highly active catalytic system showing the highest activity of 9.41 × 106 g of PE (mol of Co)−1 h−1 which is three times higher than that of prototypal cobalt catalyst (Co0) under identical conditions. Moreover, high melt temperature and unimodal molecular weight distribution are the characteristics of the resulting polyethylene.
Preparation and characterization of one‐component polyurethane powder adhesives by the solution polymerization technology
Authors: Sun Mingfen , Ren Xiue , Zhang Jianhui , Zhang Xiaoming , Wang Hongyan 
Published: May 2019

ABSTRACTA new technology integrating the synthesis and granulation was adopted to prepare the one‐component polyurethane powder adhesives (PPAs) by the solution polymerization. The influence of Rtotal, neutralization, and types of dispersion solution on the properties of PPAs was investigated. It was found that the initial melting temperature increased and storage stability decreased with increasing Rtotal. The neutralization reaction between the carboxylic group and amino group made the reduction of the sizing temperature and the increase of the T‐peel adhesion strength. The granulation behaviors of the polyurethane (PU) prepolymer under different dispersion solutions showed that the PU prepolymer can be effectively blocked by the 20–30 wt % NaHSO3 or n‐butyl alcohol. Furthermore, the blocked polymers formed small particles with the ideal sizing temperature and peel strength. The excellent adhesive property and thermal stability of PPAs could meet the requirements of the industrial gluing in the fields of packaging, lining, and footwear. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47898.
Dynamic Modulation of Supramolecular Chirality Driven by Factors from Internal to External Levels
Authors: Yue Bingbing , Zhu Liangliang 
Published: May 2019

AbstractSupramolecular chirality, generated by the asymmetric assembly of chiral or achiral molecules, has attracted intense study owing to its potential to offer insights into natural biological structures and its crucial roles in advanced materials. The optical activity and stacking pathway of building molecules both greatly determine the chirality of the whole supramolecular structure. The flexibility of supramolecular structures makes their chirality easy to modulate through abundant means. Adjustment of the molecular structure or packing mode, or external stimuli that act like a finger gently pushing toy bricks, can greatly change the chirality of supramolecular assemblies. The dynamic regulation of chiral nanostructures on the intramolecular, intermolecular, and external levels could be regarded as the modulatory essence in numerous strategies, however, this perspective is ignored in most reviews in the literature. Herein, therefore, we focus on the ingenious dynamic modulation of chiral nanostructures by these factors. Through dynamic modulation with changes in chiroptical spectroscopy and electron microscopy, the mechanism of formation of supramolecular chirality is also elaborated.
Output feedback control of wind energy conversion system involving a doubly fed induction generator
Authors: Lajouad Rachid , Giri Fouad , Chaoui Fatima Zahra , El Fadili Abderrahime , El Magri Abdelmounime 
Published: May 2019

AbstractThis paper deals with the problem of controlling a wind energy conversion system (WECS) based on the doubly fed induction generator (DFIG), by IGBT‐based back‐to‐back rectifier‐inverter. The goal of control is to maximize wind energy extraction letting the wind turbine rotor operate in a variable‐speed mode. Interestingly, the present study features the achievement of the above energetic goal without resorting to sensors for wind velocity. The control strategy involves: (i) an output feedback non‐linear regulator designed by the backstepping technique and based on the use of a high gain observer; (ii) a sensorless online reference‐speed optimizer designed using the turbine power characteristic to achieve the maximum power point tracking (MPPT) requirement. It is formally shown that the proposed controller actually meets its control objectives. This theoretical result is confirmed by several simulations.