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Advanced Materials

Thomas Tancogne-Dejean, Marianna Diamantopoulou, Maysam B Gorji, Colin Bonatti, Dirk Mohr
In lightweight engineering, there is a constant quest for low-density materials featuring high mass-specific stiffness and strength. Additively-manufactured metamaterials are particularly promising candidates as the controlled introduction of porosity allows for tailoring their density while activating strengthening size-effects at the nano- and microstructural level. Here, plate-lattices are conceived by placing plates along the closest-packed planes of crystal structures. Based on theoretical analysis, a general design map is developed for elastically isotropic plate-lattices of cubic symmetry...
September 19, 2018: Advanced Materials
Jiangzhao Chen, Nam-Gyu Park
Organic-inorganic hybrid perovskite materials are receiving increasing attention and becoming star materials on account of their unique and intriguing optical and electrical properties, such as high molar extinction coefficient, wide absorption spectrum, low excitonic binding energy, ambipolar carrier transport property, long carrier diffusion length, and high defects tolerance. Although a high power conversion efficiency (PCE) of up to 22.7% is certified for perovskite solar cells (PSCs), it is still far from the theoretical Shockley-Queisser limit efficiency (30...
September 17, 2018: Advanced Materials
Rebecca L Milot, Matthew T Klug, Christopher L Davies, Zhiping Wang, Hans Kraus, Henry J Snaith, Michael B Johnston, Laura M Herz
Optoelectronic properties are unraveled for formamidinium tin triiodide (FASnI3 ) thin films, whose background hole doping density is varied through SnF2 addition during film fabrication. Monomolecular charge-carrier recombination exhibits both a dopant-mediated part that grows linearly with hole doping density and remnant contributions that remain under tin-enriched processing conditions. At hole densities near 1020 cm-3 , a strong Burstein-Moss effect increases absorption onset energies by ≈300 meV beyond the bandgap energy of undoped FASnI3 (shown to be 1...
September 17, 2018: Advanced Materials
Ashutosh Giri, Sean W King, William A Lanford, Antonio B Mei, Devin Merrill, Liyi Li, Ron Oviedo, John Richards, David H Olson, Jeffrey L Braun, John T Gaskins, Freddy Deangelis, Asegun Henry, Patrick E Hopkins
The role of interfacial nonidealities and disorder on thermal transport across interfaces is traditionally assumed to add resistance to heat transfer, decreasing the thermal boundary conductance (TBC). However, recent computational studies have suggested that interfacial defects can enhance this thermal boundary conductance through the emergence of unique vibrational modes intrinsic to the material interface and defect atoms, a finding that contradicts traditional theory and conventional understanding. By manipulating the local heat flux of atomic vibrations that comprise these interfacial modes, in principle, the TBC can be increased...
September 17, 2018: Advanced Materials
Jian Liu, Gang Ye, Bas van der Zee, Jingjin Dong, Xinkai Qiu, Yuru Liu, Giuseppe Portale, Ryan C Chiechi, L Jan Anton Koster
It is demonstrated that the n-type thermoelectric performance of donor-acceptor (D-A) copolymers can be enhanced by a factor of >1000 by tailoring the density of states (DOS). The DOS distribution is tailored by embedding sp2 -nitrogen atoms into the donor moiety of the D-A backbone. Consequently, an electrical conductivity of 1.8 S cm-1 and a power factor of 4.5 µW m-1 K-2 are achieved. Interestingly, an unusual sign switching (from negative to positive) of the Seebeck coefficient of the unmodified D-A copolymer at moderately high dopant loading is observed...
September 17, 2018: Advanced Materials
Sebastiano Bellani, Maria Rosa Antognazza, Francesco Bonaccorso
Hydrogen is considered a promising environmentally friendly energy carrier for replacing traditional fossil fuels. In this context, photoelectrochemical cells effectively convert solar energy directly to H2 fuel by water photoelectrolysis, thereby monolitically combining the functions of both light harvesting and electrolysis. In such devices, photocathodes and photoanodes carry out the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), respectively. Here, the focus is on photocathodes for HER, traditionally based on metal oxides, III-V group and II-VI group semiconductors, silicon, and copper-based chalcogenides as photoactive material...
September 16, 2018: Advanced Materials
Taehwan Jun, Kihyung Sim, Soshi Iimura, Masato Sasase, Hayato Kamioka, Junghwan Kim, Hideo Hosono
Halide perovskites, including CsPbX3 (X = Cl, Br, I), have gained much attention in the field of optoelectronics. However, the toxicity of Pb and the low photoluminescence quantum yield (PLQY) of these perovskites hamper their use. In this work, new halide materials that meet the requirements of: (i) nontoxicity, (ii) high PLQY, and (iii) ease of fabrication of thin films via the solution process are explored. In particular, copper(I) halide compounds with low-dimensional electronic structures are considered...
September 14, 2018: Advanced Materials
Fengzhu Li, Yu Zhang, Ke-Jian Jiang, Chaoshen Zhang, Jin-Hua Huang, Huijia Wang, Haochen Fan, Pengcheng Wang, Yongjie Chen, Wenchao Zhao, Xiangjun Li, Lian-Ming Yang, YanLin Song, Yongfang Li
Methylammonium iodide (MAI) and lead iodide (PbI2 ) have been extensively employed as precursors for solution-processed MAPbI3 perovskite solar cells (PSCs). However, the MAPbI3 perovskite films directly deposited from the precursor solutions, usually suffer from poor surface coverage due to uncontrolled nucleation and crystal growth of the perovskite during the film formation, resulting in low photovoltaic conversion efficiency and poor reproducibility. Herein, propylammonium iodide and PbI2 are employed as precursors for solution deposition of propylammonium lead iodide (PAPbI3 ) perovskite film...
September 14, 2018: Advanced Materials
Boyuan Shen, Huanhuan Xie, Lin Gu, Xiao Chen, Yunxiang Bai, Zhenxing Zhu, Fei Wei
Chirality is a significant structural feature for chemistry, biology, physics, and materials science, and especially determines the electrical, mechanical, and optical properties of diverse tubular structures, such as carbon nanotubes (CNTs). To recognize the chirality of nanotubes, templates are introduced as potential tools to obtain crystalline samples with visible chiral fringes under electron microscopes. However, few efforts show optimistic results, and new understanding is desired to control the sample quality with CNT templates...
September 14, 2018: Advanced Materials
Tao He, Pawaret Leowanawat, Christian Burschka, Vladimir Stepanenko, Matthias Stolte, Frank Würthner
Many organic semiconductors (OSCs) inherit chiral alkyl chains, which ensure the desirable high solubility for solution-processing but may also lead to disorder, inhomogeneous film-formation, as well as interfacial defects due to the presence of mixtures of stereoisomers or diastereomers, which impair their peak performance. Here, single-crystal field-effect transistors (SCFETs) of a diketopyrrolopyrrole-based organic semiconductor with chiral 2-ethylhexyl substituents by sublimation in air and organic ribbon mask method are fabricated...
September 14, 2018: Advanced Materials
Gyutae Nam, Yeonguk Son, Sung O Park, Woo Cheol Jeon, Haeseong Jang, Joohyuk Park, Sujong Chae, Youngshin Yoo, Jaechan Ryu, Min Gyu Kim, Sang Kyu Kwak, Jaephil Cho
Replacing noble-metal-based oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is the key to developing efficient Zn-air batteries (ZABs). Here, a homogeneous ternary Ni46 Co40 Fe14 nanoalloy with a size distribution of 30-60 nm dispersed in a carbon matrix (denoted as C@NCF-900) as a highly efficient bifunctional electrocatalyst produced via supercritical reaction and subsequent heat treatment at 900 °C is reported. Among all the transition-metal-based electrocatalysts, the C@NCF-900 exhibits the highest ORR performance in terms of half-wave potential (0...
September 14, 2018: Advanced Materials
Geun Yeol Bae, Joong Tark Han, Giwon Lee, Siyoung Lee, Sung Won Kim, Sangsik Park, Jimin Kwon, Sungjune Jung, Kilwon Cho
Human skin imperfectly discriminates between pressure and temperature stimuli under mixed stimulation, and exhibits nonlinear sensitivity to each stimulus. Despite great advances in the field of electronic skin (E-skin), the limitations of human skin have not previously been overcome. For the first time, the development of a stimulus-discriminating and linearly sensitive bimodal E-skin that can simultaneously detect and discriminate pressure and temperature stimuli in real time is reported. By introducing a novel device design and using a temperature-independent material, near-perfect stimulus discriminability is realized...
September 14, 2018: Advanced Materials
Feng Li, Gao-Feng Han, Hyuk-Jun Noh, Ishfaq Ahmad, In-Yup Jeon, Jong-Beom Baek
Catalysts are at the heart of the hydrogen evolution reaction (HER) for the production of pure and clean hydrogen. For practical applications, the scalable synthesis of efficient HER catalysts, which work in both acidic and alkaline media, is highly desired. In this work, the mechanochemically assisted synthesis of a Ru catalyst with HER performance surpassing Pt in both acidic and alkaline media is reported. Mass production of this Ru catalyst can be achieved via a two-step procedure: the mechanochemical reaction between graphite and dry ice produces edge-carboxylic-acid-functionalized graphene nanoplatelets (CGnP); mixing a Ru precursor and the CGnP in an aqueous medium introduces Ru ions, which coordinate on the CGnP...
September 14, 2018: Advanced Materials
Tetsuya Asano, Akihiro Sakai, Satoru Ouchi, Masashi Sakaida, Akinobu Miyazaki, Shinya Hasegawa
New lithium halide solid-electrolyte materials, Li3 YCl6 and Li3 YBr6 , are found to exhibit high lithium-ion conductivity, high deformability, and high chemical and electrochemical stability, which are required properties for all-solid-state battery (ASSB) applications, particularly for large-scale deployment. The lithium-ion conductivities of cold-pressed powders surpass 1 mS cm-1 at room temperature without additional intergrain or grain boundary resistances. Bulk-type ASSB cells employing these new halide solid electrolyte materials exhibit coulombic efficiencies as high as 94% with an active cathode material of LiCoO2 without any extra coating...
September 14, 2018: Advanced Materials
Alan P Kauling, Andressa T Seefeldt, Diego P Pisoni, Roshini C Pradeep, Ricardo Bentini, Ricardo V B Oliveira, Konstantin S Novoselov, Antonio H Castro Neto
There are hundreds of companies worldwide claiming to produce "graphene," showing a large variation in its properties. A systematic and reliable protocol is developed to test graphene quality using electron microscopy, atomic force microscopy, Raman spectroscopy, elemental analysis, X-ray photoelectron spectrometry, and scanning and transmission electron microscopy, which is used to study graphene from 60 producers. The statistical nature of the liquid-phase exfoliation of graphite is established...
September 13, 2018: Advanced Materials
Jake J Hay, Aleixandre Rodrigo-Navarro, Michaela Petaroudi, Anton V Bryksin, Andrés J García, Thomas H Barker, Matthew J Dalby, Manuel Salmeron-Sanchez
Materials can be engineered to deliver specific biological cues that control stem cell growth and differentiation. However, current materials are still limited for stem cell engineering as stem cells are regulated by a complex biological milieu that requires spatiotemporal control. Here a new approach of using materials that incorporate designed bacteria as units that can be engineered to control human mesenchymal stem cells (hMSCs), in a highly dynamic-temporal manner, is presented. Engineered Lactococcus lactis spontaneously colonizes a variety of material surfaces (e...
September 12, 2018: Advanced Materials
Gao Chen, Zhiwei Hu, Yanping Zhu, Binbin Gu, Yijun Zhong, Hong-Ji Lin, Chien-Te Chen, Wei Zhou, Zongping Shao
The development of efficient bifunctional electrodes with extraordinary mass activity and robust stability is an eternal yet challenging goal for the water-splitting process. Surface reconstruction during electrocatalysis can form fresh-composition electrocatalysts with unusual amorphous phases in situ, which are more active but difficult to prepare by conventional methods. Here, a facile strategy based on fast reconstruction of amorphous nanofilm precursors is proposed for exploring precious-metal-free catalysts with good electronic conductivity, ultrahigh activity, and robust stability...
September 12, 2018: Advanced Materials
Guozhen Zhang, Li Yang, Xijun Wang, Ziye Wu, Jun Jiang, Yi Luo
Charge kinetics is a critical factor that determines working efficiencies of energy materials in their various applications. It is governed by electronic structures of the materials of interest and can be fine-tuned via purposeful adjustment of electronic structures. Recent advances in the development of energy materials with desirable electronic structures to steering charge kinetics toward specific applications are highlighted here. Two key strategies are presented: one is through the tuning of energy states and the other is to control spatial distributions of charges...
September 11, 2018: Advanced Materials
Can Yang Zhang, Jin Gao, Zhenjia Wang
Sepsis is a life-threatening disease resulted from a dysregulated host immune response to bacterial infections, continuing to cause high morbidity and mortality worldwide. Despite discoveries of many potential therapeutic targets, effective treatments of sepsis are lacking. Here, a strategy is reported to target infectious microenvironments (IMEs) via bioresponsive nanoparticles that simultaneously eliminate bacteria and alleviate the host inflammation response, thus managing sepsis in mice. The nanoparticle is made of copolymers sensitive to pH and bacterial enzymes to self-assemble into a micelle loaded with both an antibiotic (ciprofloxacin) and an anti-inflammatory agent ((2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide)...
September 11, 2018: Advanced Materials
Nicolas Broguiere, Luca Isenmann, Christian Hirt, Till Ringel, Silja Placzek, Emma Cavalli, Femke Ringnalda, Lukas Villiger, Richard Züllig, Roger Lehmann, Gerhard Rogler, Markus H Heim, Julia Schüler, Marcy Zenobi-Wong, Gerald Schwank
Epithelial organoids are simplified models of organs grown in vitro from embryonic and adult stem cells. They are widely used to study organ development and disease, and enable drug screening in patient-derived primary tissues. Current protocols, however, rely on animal- and tumor-derived basement membrane extract (BME) as a 3D scaffold, which limits possible applications in regenerative medicine. This prompted us to study how organoids interact with their matrix, and to develop a well-defined hydrogel that supports organoid generation and growth...
September 10, 2018: Advanced Materials
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