bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanoparticle‐Based Fluoroionophore for Analysis of Potassium Ion Dynamics in 3D Tissue Models and In Vivo
Authors: Müller Bernhard J. , Zhdanov Alexander V. , Borisov Sergey M. , Foley Tara , Okkelman Irina A. , Tsytsarev Vassiliy , Tang Qinggong , Erzurumlu Reha S. , Chen Yu , Zhang Haijiang , Toncelli Claudio , Klimant Ingo , Papkovsky Dmitri B. , Dmitriev Ruslan I.
Published: January 2018

The imaging of real‐time fluxes of K+ ions in live cell with high dynamic range (5–150 × 10−3m) is of paramount importance for neuroscience and physiology of the gastrointestinal tract, kidney, and other tissues. In particular, the research on high‐performance deep‐red fluorescent nanoparticle‐based biosensors is highly anticipated. It is found that boron‐dipyrromethene (BODIPY)‐based K+‐sensitive fluoroionophore FI3 encapsulated in cationic polymer RL100 nanoparticles displays unusually strong efficiency in staining of broad spectrum of cell models, such as primary neurons and intestinal organoids. Using comparison of brightness, photostability, and fluorescence lifetime imaging microscopy, it is confirmed that FI3 nanoparticles display distinctively superior intracellular staining compared to the free dye. FI3 nanoparticles in real‐time live cell imaging are evaluated and it is found highly useful for monitoring intra‐ and extracellular K+ dynamics in cultured neurons. Proof‐of‐concept in vivo brain imaging confirms applicability of the biosensor for visualization of epileptic seizures. Collectively, these data make fluoroionophore FI3 a versatile cross‐platform fluorescent biosensor, broadly compatible with diverse experimental models, and crown‐ether‐based polymer nanoparticles can provide a new venue for the design of efficient fluorescent probes.
Reinforcing the Built‐In Field for Efficient Charge Collection in Polymer Solar Cells
Authors: Lee Jong‐Hoon , Jeong Song Yi , Kim Geunjin , Park Byoungwook , Kim Junghwan , Kee Seyoung , Kim Bongseong , Lee Kwanghee
Published: January 2018

The collection efficiency of photogenerated charges in polymer solar cells (PSCs) is strongly influenced by the built‐in field (Ein) that develops across the photoactive materials. Here, by investigating the Ein‐development regimes in PSCs by introducing two types of interlayers, electric dipole layers (EDLs) and charge transport layers (CTLs), the device architecture is optimized to result in a larger Ein. By incorporating a pair of EDLs on both sides of the photoactive layer, the Ein is modulated by shifting the vacuum energy at each metal–semiconductor interface, providing a larger Ein than that in conventional PSCs using typical CTLs, such as metal oxides and/or conducting polymers. These devices using paired EDLs exhibit an average PCE of 9.8%, which far surpasses the average PCE of ≈8.5% for paired CTLs.
Rational Synthesis of Large‐Area Periodic Chemical Gradients for the Manipulation of Liquid Droplets and Gas Bubbles
Authors: Perez‐Toralla Karla , Konda Abhiteja , Bowen John J. , Jennings Emily E. , Argyropoulos Christos , Morin Stephen A.
Published: January 2018

Synthetic approaches based on the patterned deposition of volatile molecules from the vapor phase are used extensively in the creation of surface‐chemical gradients; however, the ability to generate diffusion‐controlled 1D and 2D gradients from multiple sources remains a challenge. The current work reports a one‐step approach to the synthesis of continuous and periodic chemical gradients with simple and intricate geometries using multiple sources within custom reaction chambers. Specifically, this approach provides precise, simultaneous control over the physicochemical conditions (e.g., concentration, evaporation rate, and direction of diffusion flux of the chemical moieties) and the geometrical parameters (e.g., size, shape, and position) during surface functionalization, thus enabling materials with predictable surface‐chemical gradients applicable to the manipulation and/or organization of liquid droplets and that can generate assemblies of functional solids (e.g., silver nanoparticles) that are transferrable via stamping. These surfaces can be useful to various fields, for example, molecular diagnostics and microfabrication. Furthermore, this work extends the application of these surfaces to the precise placement and manipulation of gas bubbles that can have potential use in, for example, controlling bubble nucleation in processes designed to manage heat transfer.
“All‐in‐One” Nanoparticles for Trimodality Imaging‐Guided Intracellular Photo‐magnetic Hyperthermia Therapy under Intravenous Administration
Authors: Yan Hao , Shang Wenting , Sun Xiaodan , Zhao Lingyun , Wang Jingyun , Xiong Zhiyuan , Yuan Jie , Zhang Ranran , Huang Qianli , Wang Kun , Li Baohua , Tian Jie , Kang Feiyu , Feng Si‐Shen
Published: January 2018

Great efforts have been devoted so far to combine nano‐magnetic hyperthermia and nano‐photothermal therapy to achieve encouraging additive therapeutic performance in vitro and in vivo with limitation to direct intratumoral injection and no guidance of multimodality molecular imaging. In this study, a novel multifunctional theranostic nanoplatform (MNP@PES‐Cy7/2‐DG) consisting of magnetic nanoparticles (MNPs), poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PES), Cyanine7 (Cy7), and 2‐deoxyglucose (2‐DG)‐polyethylene glycol is developed. They are then applied to combined photo‐magnetic hyperthermia therapy under intravenous administration that is simultaneously guided by trimodality molecular imaging. Remarkably, nanoparticles are found aggregated mainly in the cytoplasm of tumor cells in vitro and in vivo, and exhibit stealth‐like behavior with a long second‐phase blood circulation half‐life of 20.38 ± 4.18 h. Under the guidance of photoacoustic/near‐infrared fluorescence/magnetic resonance trimodality imaging, tumors can be completely eliminated under intracellular photo‐magnetic hyperthermia therapy with additive therapeutic effect due to precise hyperthermia. This study may promote a further exploration of such a platform for clinical applications.
Single‐Phase Mixed Transition Metal Carbonate Encapsulated by Graphene: Facile Synthesis and Improved Lithium Storage Properties
Authors: Zhang Rui , Huang Xiaoxiao , Wang Dong , Hoang Tuan K. A. , Yang Yang , Duan Xiaoming , Chen Pu , Qin Lu‐Chang , Wen Guangwu
Published: January 2018

Transition metal carbonates (TMCs) with complex composition and robust hybrid structure hold great potential as high‐performance electrode materials for lithium‐ion batteries (LIBs). However, poor ionic/electronic conductivities and large volume changes of TMCs during lithiation/delithiation processes have hindered their applications. Herein, single‐phase MnCo mixed carbonate composites encapsulated by reduced graphene oxide (MnxCo1−xCO3/RGO), in which Mn and Co species are distributed randomly in one crystal structure, are successfully synthesized through a facial liquid‐state method. When evaluated as LIB anodes, the MnxCo1−xCO3/RGO composites exhibit enhanced electrochemical performance compared with the reference CoCO3/RGO and MnCO3/RGO. Specifically, the Mn0.7Co0.3CO3/RGO delivers an ultrahigh capacity of 1454 mA h g−1 after 130 cycles at 100 mA g−1 and exhibits an ultralong cycling stability (901 mA h g−1 after 1500 cycles at 2000 mA g−1). This is the best lithium storage performance among carbonate‐based anodes reported up to date. Such superb performance is attributed to the hybrid structure and enhanced electroconductivity due to the integration of Co and Mn into one crystal structure, which is complemented by electrochemical impedance spectroscopy and density functional theory calculations. The facile synthesis, promising electrochemical results, and scientific understanding of the MnxCo1−xCO3/RGO provides a design principle and encourages more research on TMCs‐based electrodes.
Screen‐Printed Poly(3,4‐Ethylenedioxythiophene):Poly(Styrenesulfonate) Grids as ITO‐Free Anodes for Flexible Organic Light‐Emitting Diodes
Authors: Zhou Lu , Yu Mengjie , Chen Xiaolian , Nie Shuhong , Lai Wen‐Yong , Su Wenming , Cui Zheng , Huang Wei
Published: January 2018

Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) grids have been successfully constructed by roll‐to‐roll compatible screen‐printing techniques and have been used as indium tin oxide (ITO)‐free anodes for flexible organic light‐emitting diodes (OLEDs). The grid‐type transparent conductive electrodes (TCEs) can adopt thicker PEDOT: PSS grid lines to ensure the conductivity, while the mesh‐like grid structure can play an important role to maintain high optical transparency. By adjusting grid periods, grid thickness and treatment of organic additives, PEDOT: PSS TCEs with high optical transparency, low sheet resistance, and excellent mechanical flexibility have been achieved. Using the screen‐printed PEDOT: PSS grids as the anodes, ITO‐free OLEDs achieved peak current efficiency of 3.40 cd A−1 at the current density of 10 mA cm−2, which are 1.56 times better than the devices with ITO glass as the anodes. The improved efficiency is attributed to the light extraction effect and improved transparency by the grid structure. The superior optoelectronic performances of OLEDs based on flexible screen‐printed PEDOT: PSS grid anodes suggest their great prospects as ITO‐free anodes for flexible and wearable electronic applications.
Vacuum Calcination Induced Conversion of Selenium/Carbon Wires to Tubes for High‐Performance Sodium–Selenium Batteries
Authors: Yang Xuming , Wang Hongkang , Yu Denis Y. W. , Rogach Andrey L.
Published: January 2018

A vacuum calcination approach is developed to fabricate selenium/carbon composites, which does not require intensive mixing and durable heating such as in commonly used melt‐infusion methods of loading selenium into carbon hosts. Starting from carbon‐coated selenium wires prepared via a wet‐chemical reaction, selenium/carbon tubes are fabricated by a straightforward calcination process. The calcination is conducted in a confined space to reduce the insulating carbon shell under vacuum, and selenium melts but remains a constituting part of the composite. Paired with sodium metal anode, the resultant selenium/carbon tubes deliver a high reversible capacity of 601 and 509 mA h g−1 at 0.2 and 2 C normalized by the mass of selenium, which corresponds to energy and power densities of 860 and 667 Wh kg−1 at 193 and 1770 W kg−1, respectively. Such capacity and rate performance surpasses most typical cathode materials for lithium or sodium (ion) batteries, according to the comparative literature analysis. Moreover, the robust tubular‐like hollow structure of the selenium/carbon composites ensures for impressive capacity retention of more than 90% after 1000 cycles at 20 C.
Ultrahigh Rate and Long‐Life Sodium‐Ion Batteries Enabled by Engineered Surface and Near‐Surface Reactions
Authors: Zhao Changtai , Yu Chang , Qiu Bo , Zhou Si , Zhang Mengdi , Huang Huawei , Wang Biqiong , Zhao Jijun , Sun Xueliang , Qiu Jieshan
Published: January 2018

To achieve the high‐power sodium‐ion batteries, the solid‐state ion diffusion in the electrode materials is a highly concerned issue and needs to be solved. In this study, a simple and effective strategy is reported to weaken and degrade this process by engineering the intensified surface and near‐surface reactions, which is realized by making use of a sandwich‐type nanoarchitecture composed of graphene as electron channels and few‐layered MoS2 with expanded interlayer spacing. The unique 2D sheet‐shaped hierarchical structure is capable of shortening the ion diffusion length, while the few‐layered MoS2 with expanded interlayer spacing has more accessible surface area and the decreased ion diffusion resistance, evidenced by the smaller energy barriers revealed by the density functional theory calculations. Benefiting from the shortened ion diffusion distance and enhanced electron transfer capability, a high ratio of surface or near‐surface reactions is dominated at a high discharge/charge rate. As such, the composites exhibit the high capacities of 152 and 93 mA h g−1 at 30 and 50 A g−1, respectively. Moreover, a high reversible capacity of 684 mA h g−1 and an excellent cycling stability up to 4500 cycles can be delivered. The outstanding performance is attributed to the engineered structure with increased contribution of surface or near‐surface reactions.
Light‐Emitting Transition Metal Dichalcogenide Monolayers under Cellular Digestion
Authors: Yeh Yin‐Ting , Tang Yi , Lin Zhong , Fujisawa Kazunori , Lei Yu , Zhou Yijing , Rotella Christopher , Elías Ana Laura , Zheng Si‐Yang , Mao Yingwei , Liu Zhiwen , Lu Huaguang , Terrones Mauricio
Published: January 2018

2D materials cover a wide spectrum of electronic properties. Their applications are extended from electronic, optical, and chemical to biological. In terms of biomedical uses of 2D materials, the interactions between living cells and 2D materials are of paramount importance. However, biointerfacial studies are still in their infancy. This work studies how living organisms interact with transition metal dichalcogenide monolayers. For the first time, cellular digestion of tungsten disulfide (WS2) monolayers is observed. After digestion, cells intake WS2 and become fluorescent. In addition, these light‐emitting cells are not only viable, but also able to pass fluorescent signals to their progeny cells after cell division. By combining synthesis of 2D materials and a cell culturing technique, a procedure for monitoring the interactions between WS2 monolayers and cells is developed. These observations open up new avenues for developing novel cellular labeling and imaging approaches, thus triggering further studies on interactions between 2D materials and living organisms.
Antigen‐Directed Fabrication of a Multifunctional Nanovaccine with Ultrahigh Antigen Loading Efficiency for Tumor Photothermal‐Immunotherapy
Authors: Pan Jinbin , Wang Yaqiong , Zhang Cai , Wang Xiaoyi , Wang Haoyu , Wang Jiaojiao , Yuan Yizhong , Wang Xu , Zhang Xuejun , Yu Chunshui , Sun Shao‐Kai , Yan Xiu‐Ping
Published: January 2018

Current antigen‐encapsulated multifunctional nanovaccines for oncotherapy suffer from limited antigen loading efficiency, low yield, tedious manufacture, and systemic toxicity. Here, an antigen‐directed strategy for the fabrication of multifunctional nanovaccine with ultrahigh antigen loading efficiency in a facile way for tumor photothermal‐immunotherapy is shown. As a proof of concept, a model antigen ovalbumin (OVA) is used as a natural carrier to load a representative theranostic agent indocyanine green (ICG). Mixing OVA and ICG in aqueous solution gives the simplest multifunctional nanovaccine so far. The nanovaccine owns antigen loading efficiency of 80.8%, high yield of >90%, intense near‐infrared absorption and fluorescence, excellent reproducibility, good aqueous solubility and stability, and favorable biocompatibility. These merits not only guarantee sensitive labeling/tracking and efficient stimulation of dendritic cells, but also reliable imaging‐guided photothermal‐immunotherapy of tumors and tumor prevention. The proposed strategy provides a facile and robust method for large‐scale and reproducible fabrication of multifunctional nanovaccines with ultrahigh antigen loading efficiency for tumor therapy.
Investigating the Hybrid‐Structure‐Effect of CeO2‐Encapsulated Au Nanostructures on the Transfer Coupling of Nitrobenzene
Authors: Li Jian , Song Shuyan , Long Yan , Wu Lanlan , Wang Xiao , Xing Yan , Jin Rongchao , Liu Xiaogang , Zhang Hongjie
Published: January 2018

Due to the obvious distinctions in structure, core–shell nanostructures (CSNs) and yolk–shell nanostructures (YSNs) exhibit different catalytic behavior for specific organic reactions. In this work, two unique autoredox routes are developed to the fabrication of CeO2‐encapsulated Au nanocatalysts. Route A is the synthesis of well‐defined CSNs by a one‐step redox reaction. The process involves an interesting phenomenon in which Ce3+ can act as a weak acid to inhibit the hydrolysis of Ce4+ under the condition of OH− shortage. Route B is the fabrication of monodispersed YSNs by a two‐step redox reaction with amorphous Co3O4 as an in situ template. Furthermore, the transfer coupling of nitrobenzene is chosen as a probe reaction to investigate their catalytic difference. The CSNs can gradually achieve the conversion of nitrobenzene into azoxybenzene, while the YSNs can rapidly convert nitrobenzene into azobenzene. The different catalytic results are mainly attributed to their structural distinctions.
A Simple Route to Porous Graphene from Carbon Nanodots for Supercapacitor Applications
Authors: Strauss Volker , Marsh Kris , Kowal Matthew D. , El‐Kady Maher , Kaner Richard B.
Published: January 2018

A facile method to convert biomolecule‐based carbon nanodots (CNDs) into high‐surface‐area 3D‐graphene networks with excellent electrochemical properties is presented. Initially, CNDs are synthesized by microwave‐assisted thermolysis of citric acid and urea according to previously published protocols. Next, the CNDs are annealed up to 400 °C in a tube furnace in an oxygen‐free environment. Finally, films of the thermolyzed CNDs are converted into open porous 3D turbostratic graphene (3D‐ts‐graphene) networks by irradiation with an infrared laser. Based upon characterizations using scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray diffraction, Fourier‐transform infrared spectroscopy, and Raman spectroscopy, a feasible reaction mechanism for both the thermolysis of the CNDs and the subsequent laser conversion into 3D‐ts‐graphene is presented. The 3D‐ts‐graphene networks show excellent morphological properties, such as a hierarchical porous structure and a high surface area, as well as promising electrochemical properties. For example, nearly ideal capacitive behavior with a volumetric capacitance of 27.5 mF L−1 is achieved at a current density of 560 A L−1, which corresponds to an energy density of 24.1 mWh L−1 at a power density of 711 W L−1. Remarkable is the extremely fast charge–discharge cycling rate with a time constant of 3.44 ms.
Recent Advances in Wearable Transdermal Delivery Systems
Authors: Amjadi Morteza , Sheykhansari Sahar , Nelson Bradley J. , Sitti Metin
Published: January 2018

Wearable transdermal delivery systems have recently received tremendous attention due to their noninvasive, convenient, and prolonged administration of pharmacological agents. Here, the material prospects, fabrication processes, and drug‐release mechanisms of these types of therapeutic delivery systems are critically reviewed. The latest progress in the development of multifunctional wearable devices capable of closed‐loop sensation and drug delivery is also discussed. This survey reveals that wearable transdermal delivery has already made an impact in diverse healthcare applications, while several grand challenges remain.
Mixed Ionic and Electronic Conductor for Li‐Metal Anode Protection
Authors: Yan Jianhua , Yu Jianyong , Ding Bin
Published: January 2018

Li‐metal is the optimal choice as an anode due to its highest energy density. However, Li‐anodes suffer safety problems from dendritic Li‐growth and continuous corrosion by liquid electrolytes. Here, an effective strategy of using ultrathin and conformal mixed ionic and electronic ceramic conductor (MIEC) is proposed to stabilize Li‐anodes. An ultrathin Li0.35La0.52[V]0.13TiO3 (LLTO) ceramic film with superior ionic conductivity is first obtained by sintering single‐crystal LLTO nanoparticles, which have controlled surface facets and particle sizes. Then the MIEC property is developed in the LLTO film by introducing toluene as catalyst, which triggers the chemical reactions between LLTO and Li‐metal, leading to high electronic conductivity in the LLTO film. After evaporating toluene, a hybrid LLTO/Li anode with a conformal and stable interface is formed. When applying the hybrid anodes in Li‐metal batteries, the MIEC ceramic film blocks Li‐corrosion from electrolyte and the formation of Li‐dendrites by buffering the Li‐ion concentration gradient and leveling secondary current distribution on Li‐metal surface. At the same time, the Coulombic efficiency of batteries reaches to 98%. This finding will impact the general approach for tailoring the properties of Li‐metal anodes for achieving better Li‐metal battery performance.
Argon Plasma Treatment to Tune Perovskite Surface Composition for High Efficiency Solar Cells and Fast Photodetectors
Authors: Xiao Xun , Bao Chunxiong , Fang Yanjun , Dai Jun , Ecker Benjamin R. , Wang Congcong , Lin Yuze , Tang Shi , Liu Ye , Deng Yehao , Zheng Xiaopeng , Gao Yongli , Zeng Xiao Cheng , Huang Jinsong
Published: January 2018

The surface composition of perovskite films is very sensitive to film processing and can deviate from the optimal, which generates unfavorable defects and results in efficiency loss in solar cells and slow response speed in photodetectors. An argon plasma treatment is introduced to modify the surface composition by tuning the ratio of organic and inorganic components as well as defect type before deposition of the passivating layer. It can efficiently enhance the charge collection across the perovskite–electrode interface by suppressing charge recombination. Therefore, perovskite solar cells with argon plasma treatment yield enhanced efficiency to 20.4% and perovskite photodetectors can reach their fastest respond speed, which is solely limited by the carrier mobility.
Coupling Mechanical and Electrical Properties in Spin Crossover Polymer Composites
Authors: Rat Sylvain , Piedrahita‐Bello Mario , Salmon Lionel , Molnár Gábor , Demont Philippe , Bousseksou Azzedine
Published: January 2018

Spin crossover particles of formula [Fe{(Htrz)2(trz)}0.9(NH2‐trz)0.3](BF4)1.1 and average size of 20 nm ± 8 nm are homogeneously dispersed in poly(vinylidene fluoride‐co‐trifluoro‐ethylene), P(VDF‐TrFE), and poly(vinylidene fluoride) (PVDF) matrices to form macroscopic (cm‐scale), freestanding, and flexible nanocomposite materials. The composites exhibit concomitant thermal expansion and discharge current peaks on cycling around the spin transition temperatures, i.e., new “product properties” resulting from the synergy between the particles and the matrix. Poling the P(VDF‐TrFE) (70–30 mol%) samples loaded with 25 wt% of particles in 18 MV m−1 electric field results in a piezoelectric coefficient d33 = −3.3 pC N−1. The poled samples display substantially amplified discharges and altered spin transition properties. Analysis of mechanical and dielectric properties reveals that both strain (1%) and permittivity (40%) changes in the composite accompany the spin transition in the particles, giving direct evidence for strong electromechanical couplings between the components. These results provide a novel route for the deployment of molecular spin crossover materials as actuators in artificial muscles and generators in thermal energy harvesting devices.
Surpassing 10% Efficiency Benchmark for Nonfullerene Organic Solar Cells by Scalable Coating in Air from Single Nonhalogenated Solvent
Authors: Ye Long , Xiong Yuan , Zhang Qianqian , Li Sunsun , Wang Cheng , Jiang Zhang , Hou Jianhui , You Wei , Ade Harald
Published: January 2018

The commercialization of nonfullerene organic solar cells (OSCs) critically relies on the response under typical operating conditions (for instance, temperature and humidity) and the ability of scale‐up. Despite the rapid increase in power conversion efficiency (PCE) of spin‐coated devices fabricated in a protective atmosphere, the efficiencies of printed nonfullerene OSC devices by blade coating are still lower than 6%. This slow progress significantly limits the practical printing of high‐performance nonfullerene OSCs. Here, a new and relatively stable nonfullerene combination is introduced by pairing the nonfluorinated acceptor IT‐M with the polymeric donor FTAZ. Over 12% efficiency can be achieved in spin‐coated FTAZ:IT‐M devices using a single halogen‐free solvent. More importantly, chlorine‐free, blade coating of FTAZ:IT‐M in air is able to yield a PCE of nearly 11% despite a humidity of ≈50%. X‐ray scattering results reveal that large π–π coherence length, high degree of face‐on orientation with respect to the substrate, and small domain spacing of ≈20 nm are closely correlated with such high device performance. The material system and approach yield the highest reported performance for nonfullerene OSC devices by a coating technique approximating scalable fabrication methods and hold great promise for the development of low‐cost, low‐toxicity, and high‐efficiency OSCs by high‐throughput production.
Designer Shape Anisotropy on Transition‐Metal‐Dichalcogenide Nanosheets
Authors: Martella Christian , Mennucci Carlo , Lamperti Alessio , Cappelluti Emmanuele , de Mongeot Francesco Buatier , Molle Alessandro
Published: January 2018

MoS2 and generally speaking, the wide family of transition‐metal dichalcogenides represents a solid nanotechnology platform on which to engineer a wealth of new and outperforming applications involving 2D materials. An even richer flexibility can be gained by extrinsically inducing an in‐plane shape anisotropy of the nanosheets. Here, the synthesis of anisotropic MoS2 nanosheets is proposed as a prototypical example in this respect starting from a highly conformal chemical vapor deposition on prepatterend substrates and aiming at the more general purpose of tailoring anisotropy of 2D nanosheets by design. This is envisioned to be a suitable configuration for strain engineering as far as strain can be spatially redistributed in morphologically different regions. With a similar approach, both the optical and electronic properties of the 2D transition‐metal dichalcogenides can be tailored over macroscopic sample areas in a self‐organized fashion, thus paving the way for new applications in the field of optical metasurfaces, light harvesting, and catalysis.
Ordering pH‐Responsive Polyelectrolyte‐Grafted Nanoparticles in a Flow Coating Process
Authors: Zhang Chongfeng , Carlson Thomas , Yang Siyang , Akcora Pinar
Published: January 2018

The effects of nanoscale particle interactions on deposition patterns in the flow coating process are investigated using pH‐responsive poly(acrylic acid) (PAA)‐grafted silica nanoparticles. Interactions between nanoparticles are effectively controlled by grafting densities, PAA brush lengths, and pH, in addition to hydrogen bonding between free polyvinylpyrrolidone (PVP) and PAA. Consequently, various intriguing patterns of randomly distributed dots, polygonal networks, meshes, fork‐like structures along with highly regulated and densely packed stripes parallel to the moving direction of substrates are fabricated. Per se, the flow coating process is shown to form regulated patterns during evaporation by controlling particle–particle interactions with inherent brush properties and external pH.
Vapor‐Phase Polymerization and Carbonization to Nitrogen‐Doped Carbon Nanoscale Networks with Designable Pore Geometries Templated from Block Copolymers
Authors: Zhang Ang , Qu Ting , Cao Shubo , Li Yayuan , Zhao Yongbin , Chen Aihua
Published: January 2018

3D interconnected nitrogen‐doped carbon nanoscale networks (N‐CNNs) with designable pore geometries are prepared by vapor‐phase polymerization approach and subsequent carbonization using self‐assembled block copolymer (BCP) polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP) with bicontinuous structures as templates. PS‐b‐P4VP monolithic membranes composed of interconnected micellar fibers or spheres with PS@P4VP core–shell structure are obtained by swelling lamellar supramolecular membranes of PS‐b‐P4VP and 3‐n‐pentadecylphenol (PDP) via hydrogen bonding. Importantly, the morphologies of self‐assembled BCP can be tuned by just adjusting swelling time for the same PS‐b‐P4VP(PDP). The vapor‐phase polymerization strategy is adopted for the first time to complex iodine to P4VP shell layers and subsequently initiates the polymerization of pyrrole to form polypyrrole on the outside of PS@P4VP core–shell structures. After carbonization, the BCP templates are removed and N‐CNNs with different pore geometries are obtained. The interconnected network structures and the introduction of nitrogen in carbon nanoscale networks make them particularly promising in many applications such as oxygen reduction reaction (ORR). The N‐CNN templated from micellar fibers (N‐CNN‐F), as a metal‐free ORR catalyst, displays comparable performance with Pt/C in alkaline media. The study provides not only a new synthesis method, but also important insight into designing 3D networks with open‐celled pores for ORR and other applications.
3D Printed Optical Quality Silica and Silica–Titania Glasses from Sol–Gel Feedstocks
Authors: Destino Joel F. , Dudukovic Nikola A. , Johnson Michael A. , Nguyen Du T. , Yee Timothy D. , Egan Garth C. , Sawvel April M. , Steele William A. , Baumann Theodore F. , Duoss Eric B. , Suratwala Tayyab , Dylla‐Spears Rebecca
Published: January 2018

A method for fabricating optical quality silica and silica–titania glasses by three‐dimensional (3D) printing is reported. Key to this success is the combination of sol–gel derived silica and silica–titania colloidal feedstocks, direct ink writing (DIW) technology, and conventional glass thermal processing methods. Printable silica and silica–titania sol inks are prepared directly from molecular precursors by a simple one‐pot method, which is optimized to yield viscous, shear‐thinning colloidal suspensions with tuned rheology ideal for DIW. After printing, the parts are dried and sintered under optimized thermal conditions to ensure complete organic removal and uniform densification without crystallization. Characterizations of the 3D‐printed pure silica and silica–titania glasses show that they are equivalent to commercial optical fused silica and silica–titania glasses. More specifically, they exhibit comparable chemical composition, SiO2 network structure, refractive index, dispersion, optical transmission, and coefficient of thermal expansion. 3D‐printed silica and silica–titania glasses also exhibit comparable polished surface roughness and meet refractive index homogeneity standards within range of commercial optical grade glasses. This method establishes 3D printing as a viable tool to create optical glasses with compositional and geometric configurations that are inaccessible by conventional optical fabrication methods.
Excitations Partition into Two Distinct Populations in Bulk Perovskites
Authors: Wang Lili , Brawand Nicholas P. , Vörös Márton , Dahlberg Peter D. , Otto John P. , Williams Nicholas E. , Tiede David M. , Galli Giulia , Engel Gregory S.
Published: January 2018

Organolead halide perovskites convert optical excitations to charge carriers with remarkable efficiency in optoelectronic devices. Previous research predominantly documents dynamics in perovskite thin films; however, extensive disorder in this platform may obscure the observed carrier dynamics. Here, carrier dynamics in perovskite single‐domain single crystals is examined by performing transient absorption spectroscopy in a transmissive geometry. Two distinct sets of carrier populations that coexist at the same radiation fluence, but display different decay dynamics, are observed: one dominated by second‐order recombination and the other by third‐order recombination. Based on ab initio simulations, this observation is found to be most consistent with the hypothesis that free carriers and localized carriers coexist due to polaron formation. The calculations suggest that polarons will form in both CH3NH3PbBr3 and CH3NH3PbI3 crystals, but that they are more pronounced in CH3NH3PbBr3. Single‐crystal CH3NH3PbBr3 could represent the key to understanding the impact of polarons on the transport properties of perovskite optoelectronic devices.
Moiré Metamaterials and Metasurfaces
Authors: Wu Zilong , Zheng Yuebing
Published: January 2018

Optical metamaterials and metasurfaces enable versatile light manipulations. Advancements in modeling, nanofabrication, and characterization tools have led to the development of metamaterials and metasurfaces for many applications: energy conversion, biomedicine, and information technology. Recently, metamaterials and metasurfaces with moiré configurations have attracted strong interest due to their highly tunable optical responses and high‐throughput fabrication. Herein, state‐of‐the‐art moiré metamaterials and metasurfaces are reviewed. The presentation covers fabrication techniques, structure–property relationships, and applications in lasing and biomedical sensing. The review concludes with challenges and opportunities for moiré metamaterials and metasurfaces.
Trapped‐Electron‐Induced Hole Injection in Perovskite Photodetector with Controllable Gain
Authors: Zhang Dezhong , Liu Chunyu , Li Kanzhe , Guo Wenbin , Gao Fengli , Zhou Jingran , Zhang Xindong , Ruan Shengping
Published: January 2018

Perovskite is an excellent photosensitive material but it exhibits a shortcoming in providing photoconductive gain for layered photodetectors due to lacking of trap states. Here, the perovskite photodetectors are fabricated with controllable photoconductive gain by designing a trapped‐electron‐induced hole injection structure of [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM):2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ)/Bathocuproine/Au. The deep trap states provided by F4‐TCNQ can capture the photogenerated electrons from perovskite, which makes the hole injection barrier thin enough to be tunneled through, allowing the hole injection and forming a gain. Meanwhile, the gain is controllable by adjusting the electron trapping and hole transport capacities of PCBM:F4‐TCNQ dual‐functional layer, concomitantly realizing the transition of device from photovoltaic to photoconductive. Thus fabricated device achieves a higher external quantum efficiency of 6 × 104% at a lower bias of −1 V, and simultaneously maintains the rectifying behavior in dark, providing the detectivity of about 1 × 1015 Jones.
Single‐Shot Laser Additive Manufacturing of High Fill‐Factor Microlens Arrays
Authors: Surdo Salvatore , Carzino Riccardo , Diaspro Alberto , Duocastella Martí
Published: January 2018

High fill‐factor microlens arrays (MLA) are key for improving photon collection efficiency in light‐sensitive devices. Although several techniques are now capable of producing high‐quality MLA, they can be limited in fill‐factor, precision, the range of suitable substrates, or the possibility to generate arbitrary arrays. Here, a novel additive direct‐write method for rapid and customized fabrication of high fill‐factor MLA over a variety of substrates is demonstrated. This approach uses a single laser pulse to delaminate and catapult a polymeric microdisc from a film onto a substrate of interest. Following a thermal reflow process, the printed disc can be converted into a planoconvex microlens offering excellent sphericity and high smoothness (RRMS < 40 Å). Importantly, the transfer of solid microdiscs enables fill‐factors close to 100%, not achievable with standard direct‐write methods such as inkjet printing or microdispensing. Arbitrary generation of MLA over flexible and curved surfaces, with microlenses presenting a curvature ranging from 20 to 240 µm and diffraction‐limited performance, is demonstrated. The ease of implementation and versatility of the approach, combined with its potential parallelization, paves the way for the high‐throughput fabrication of tailored MLA directly on top of functional devices.
Polarization Photoelectric Conversion in Layered GeS
Authors: Hsueh Hung‐Chung , Li Jia‐Xuan , Ho Ching‐Hwa
Published: January 2018

Polarization photovoltaic effect is a unique character for an energy material with specific in‐plane anisotropy. Especially, if the energy material has a direct bandgap close to 1.6 eV, it will efficiently absorb full sunlight spectrum with specific axial polarization. In this study, polarized microtransmittance measurements of GeS multilayer with polarization angles ranging from θ = 0° (E || a) [through 90° (E || b)] to θ = 180° (E || a) have been studied near band edge. The polarized absorption edge follows a sinusoidal variation of E(θ) = 1.6 + 0.05⋅|sin(θ)| eV with respect to the angle change of the polarized absorption spectra. This anisotropic optical response is well reproduced by first‐principles calculations based on a combined Green's function technique, the GW–Bethe–Salpeter equation (BSE) approach. To characterize highly anisotropic band structure of layered GeS, polarized thermoreflectance measurement and first‐principles quasiparticle band‐structure calculations are also carried out. The interband transitions belonging to E ||a and E ||b polarizations are respectively identified. The polarized surface photovoltaic effects of a GeS Schottky solar cell are also tested. The special in‐plane optical anisotropy (along a and perpendicular to the a axis) renders GeS owning highly bi‐axial responsivity with respect to the c‐plane photoelectric conversion.
1D SbSeI, SbSI, and SbSBr With High Stability and Novel Properties for Microelectronic, Optoelectronic, and Thermoelectric Applications
Authors: Peng Bo , Xu Ke , Zhang Hao , Ning Zeyu , Shao Hezhu , Ni Gang , Li Jing , Zhu Yongyuan , Zhu Heyuan , Soukoulis Costas M.
Published: January 2018

Mechanical exfoliation of 2D materials has triggered an explosive interest in low dimensional material research. We extend this idea to 1D van der‐Waals materials. Three 1D semiconductors (SbSeI, SbSI, and SbSBr) with high stability and novel electronic properties are discovered using first principles calculations. Both the dynamical and the thermal stability of these 1D materials are examined. We demonstrate that their nanowire thinner than 7 Å can be easily obtained by mechanical exfoliation, hydrothermal method, or sonochemical method. The bulk‐to‐1D transition results in dramatic changes in band gap, effective mass, and static dielectric constant due to quantum confinement, making 1D SbSeI a highly promising channel material for transistors with gate length shorter than 1 nm. Under small uniaxial strain, these materials are transformed from indirect into direct band gap semiconductors, paving the way for optoelectronic devices and mechanical sensors. Moreover, the thermoelectric performance of these materials is significantly improved over their bulk counterparts. These highly desirable properties render SbSeI, SbSI, and SbSBr promising 1D materials for applications in future microelectronics, optoelectronics, mechanical sensors, and thermoelectrics.
Focused Ultrasound‐Augmented Delivery of Biodegradable Multifunctional Nanoplatforms for Imaging‐Guided Brain Tumor Treatment
Authors: Wu Meiying , Chen Wenting , Chen Yu , Zhang Haixian , Liu Chengbo , Deng Zhiting , Sheng Zonghai , Chen Jingqin , Liu Xin , Yan Fei , Zheng Hairong
Published: January 2018

The blood brain barrier is the main obstacle to delivering diagnostic and therapeutic agents to the diseased sites of brain. It is still of great challenge for the combined use of focused ultrasound (FUS) and theranostic nanotechnology to achieve noninvasive and localized delivery of chemotherapeutic drugs into orthotopic brain tumor. In this work, a unique theranostic nanoplatform for highly efficient photoacoustic imaging‐guided chemotherapy of brain tumor both in vitro and in vivo, which is based on the utilization of hollow mesoporous organosilica nanoparticles (HMONs) to integrate ultrasmall Cu2−xSe particles on the surface and doxorubicin inside the hollow interior, is synthesized. The developed multifunctional theranostic nanosystems exhibit tumor‐triggered programmed destruction due to the reducing microenvironment‐responsive cleavage of disulfide bonds that are incorporated into the framework of HMONs and linked between HMONs and Cu2−xSe, resulting in tumor‐specific biodegradation and on‐demand drug‐releasing behavior. Such tumor microenvironment‐responsive biodegradable and biocompatible theranostic nanosystems in combination with FUS provide a promising delivery nanoplatform with high performance for orthotopic brain tumor imaging and therapy.
Tin Selenide (SnSe): Growth, Properties, and Applications
Authors: Shi Weiran , Gao Minxuan , Wei Jinping , Gao Jianfeng , Fan Chenwei , Ashalley Eric , Li Handong , Wang Zhiming
Published: January 2018

The indirect bandgap semiconductor tin selenide (SnSe) has been a research hotspot in the thermoelectric fields since a ZT (figure of merit) value of 2.6 at 923 K in SnSe single crystals along the b‐axis is reported. SnSe has also been extensively studied in the photovoltaic (PV) application for its extraordinary advantages including excellent optoelectronic properties, absence of toxicity, cheap raw materials, and relative abundance. Moreover, the thermoelectric and optoelectronic properties of SnSe can be regulated by the structural transformation and appropriate doping. Here, the studies in SnSe research, from its evolution to till now, are reviewed. The growth, characterization, and recent developments in SnSe research are discussed. The most popular growth techniques that have been used to prepare SnSe materials are discussed in detail with their recent progress. Important phenomena in the growth of SnSe as well as the problems remaining for future study are discussed. The applications of SnSe in the PV fields, Li‐ion batteries, and other emerging fields are also discussed.
Recent Advances on Functionalized Upconversion Nanoparticles for Detection of Small Molecules and Ions in Biosystems
Authors: Gu Bin , Zhang Qichun
Published: January 2018

Significant progress on upconversion‐nanoparticle (UCNP)‐based probes is witnessed in recent years. Compared with traditional fluorescent probes (e.g., organic dyes, metal complexes, or inorganic quantum dots), UCNPs have many advantages such as non‐autofluorescence, high chemical stability, large light‐penetration depth, long lifetime, and less damage to samples. This article focuses on recent achievements in the usage of lanthanide‐doped UCNPs as efficient probes for biodetection since 2014. The mechanisms of upconversion as well as the luminescence resonance energy transfer process is introduced first, followed by a detailed summary on the recent researches of UCNP‐based biodetections including the detection of inorganic ions, gas molecules, reactive oxygen species, and thiols and hydrogen sulfide.
Recent Advances in Sensitized Photocathodes: From Molecular Dyes to Semiconducting Quantum Dots
Authors: Wu Hao‐Lin , Li Xu‐Bing , Tung Chen‐Ho , Wu Li‐Zhu
Published: January 2018

The increasing demand for sustainable and environmentally benign energy has stimulated intense research to establish highly efficient photo‐electrochemical (PEC) cells for direct solar‐to‐fuel conversion via water splitting. Light absorption, as the initial step of the catalytic process, is regarded as the foundation of establishing highly efficient PEC systems. To make full use of visible light, sensitization on photoelectrodes using either molecular dyes or semiconducting quantum dots provides a promising method. In this field, however, there remain many fundamental issues to be solved, which need in‐depth study. Here, fundamental knowledge of PEC systems is introduced to enable readers a better understanding of this field. Then, the development history and current state in both molecular dye‐ and quantum dot‐sensitized photocathodes for PEC water splitting are discussed. A systematical comparison between the two systems has been made. Special emphasis is placed on the research of quantum dot‐sensitized photocathodes, which have shown superiority in both efficiency and durability towards PEC water splitting at the present stage. Finally, the opportunities and challenges in the future for sensitized PEC water‐splitting systems are proposed.
Si‐Doped Cu(In,Ga)Se2 Photovoltaic Devices with Energy Conversion Efficiencies Exceeding 16.5% without a Buffer Layer
Authors: Ishizuka Shogo , Nishinaga Jiro , Iioka Masayuki , Higuchi Hirofumi , Kamikawa Yukiko , Koida Takashi , Shibata Hajime , Fons Paul
Published: January 2018

In this communication, novel and simplified structure Cu(In,Ga)Se2 (CIGS) solar cells, which nominally consist of only a CIGS photoabsorber layer sandwiched between back and front contact layers but yet demonstrate high photovoltaic efficiencies, are reported. To realize this accomplishment, Si‐doped CIGS films grown by the three‐stage coevaporation method, B‐doped ZnO transparent conductive oxide front contact layers deposited by chemical vapor deposition, and heat–light soaking treatments are used. Si‐doping of CIGS films is found to modify the film surfaces and grain boundary properties and also affect the alkali metal distribution profiles in CIGS films. These effects are expected to contribute to improvements in buffer‐free CIGS device performance. Heat–light soaking treatments, which are occasionally performed to improve conventional buffer‐based CIGS device performance, are found to be also effective in enhancing buffer‐free CIGS photovoltaic efficiencies. This result suggests that the mechanism behind the beneficial effects of heat–light soaking treatments originates from CIGS bulk issues and is independent of the buffer materials. Consequently, over 16.5% efficiencies, including an independently certified value, are demonstrated from completely buffer‐free CIGS photovoltaic devices.
Less is More: Dopant‐Free Hole Transporting Materials for High‐Efficiency Perovskite Solar Cells
Authors: Zhou Weiqi , Wen Zhenhai , Gao Peng
Published: January 2018

Perovskite solar cells have delivered power conversion efficiency beyond 22% in less than seven years, implying the potential for the paradigm shift of low‐cost photovoltaics with high efficiency and low embedded energy. Besides the “perovskite fever,” the development of new hole transport materials (HTM), especially dopant‐free HTMs, is another research hotspot. This is because the currently used HTMs, such as spiro‐OMeTAD derivatives, require additional chemical doping process to ensure sufficient conductivity and proper ionic potential level for efficient hole transport and collection. However, the commonly used dopants are volatile and hygroscopic which not only increase the complexity and cost of device fabrication but also deteriorate the device stability. So far, there have been several reviews on new HTMs, but review or analysis on dopant‐free HTMs is scarce. In this review, all reported dopant‐free HTMs are categorized into four primary different types and lessons will be learned during the separate discussions. The stability test behavior of all the intrinsic HTMs will be evaluated directly. In the end, the correlations between the properties of the intrinsic HTMs and parameters of the devices will be plotted to shed light on the future direction of development of this field.