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Mobility bands

Cheng Chang, Minghui Wu, Dongsheng He, Yanling Pei, Chao-Feng Wu, Xuefeng Wu, Hulei Yu, Fangyuan Zhu, Kedong Wang, Yue Chen, Li Huang, Jing-Feng Li, Jiaqing He, Li-Dong Zhao
Thermoelectric technology enables the harvest of waste heat and its direct conversion into electricity. The conversion efficiency is determined by the materials figure of merit ZT Here we show a maximum ZT of ~2.8 ± 0.5 at 773 kelvin in n-type tin selenide (SnSe) crystals out of plane. The thermal conductivity in layered SnSe crystals is the lowest in the out-of-plane direction [two-dimensional (2D) phonon transport]. We doped SnSe with bromine to make n-type SnSe crystals with the overlapping interlayer charge density (3D charge transport)...
May 18, 2018: Science
Min-Hye Jeong, Dohyun Kwak, Hyun-Soo Ra, A-Young Lee, Jong-Soo Lee
Few-layer black phosphorus has shown great potential for next-generation electronics with tunable band gap and high carrier mobility. For the electronic applications, the thickness modulation of a BP flake is an essential due to its thickness-dependent electronic properties. However, controlling the precise thickness of few-layer BP is a challenge for the high-performance device applications. In this study, we demonstrate that thermal treatment under ambient condition precisely controls the thickness of BP flake...
May 17, 2018: ACS Applied Materials & Interfaces
Lijuan Li, Hui Lin, Xiao Kong, Xiaoyang Du, Xinwei Chen, Ling Zhou, Silu Tao, Caijun Zheng, Xiaohong Zhang
Ternary blend systems have been used to enhance the short-circuit current density (JSC) and fill factor (FF) of organic solar cells (OSCs). However, it is still a challenge to find suitable third components that concurrently possess complementary light absorption and well-matched energy levels. Here, a small organic molecule, 4,4'-(9,9-dihexyl-9H-fluorene-2,7-diyl)bis(N,N-bis(4-(pyren-1-yl)phenyl)anili-ne) (DFNPy), which contains a triphenylamine core and bulky pyrene rings, was designed and used to construct ternary blend OSCs...
May 17, 2018: Nanoscale
Yuan Liu, Jian Guo, Enbo Zhu, Lei Liao, Sung-Joon Lee, Mengning Ding, Imran Shakir, Vincent Gambin, Yu Huang, Xiangfeng Duan
The junctions formed at the contact between metallic electrodes and semiconductor materials are crucial components of electronic and optoelectronic devices 1 . Metal-semiconductor junctions are characterized by an energy barrier known as the Schottky barrier, whose height can, in the ideal case, be predicted by the Schottky-Mott rule2-4 on the basis of the relative alignment of energy levels. Such ideal physics has rarely been experimentally realized, however, because of the inevitable chemical disorder and Fermi-level pinning at typical metal-semiconductor interfaces2,5-12 ...
May 16, 2018: Nature
You-Jyun Chen, Ming-Hsien Li, Jung-Chun-Andrew Huang, Peter Chen
Cu/Cu2 O films grown by ion beam sputtering were used as p-type modified layers to improve the efficiency and stability of perovskite solar cells (PSCs) with an n-i-p heterojunction structure. The ratio of Cu to Cu2 O in the films can be tuned by the oxygen flow ratio (O2 /(O2  + Ar)) during the sputtering of copper. Auger electron spectroscopy was performed to determine the elemental composition and chemical state of Cu in the films. Ultraviolet photoelectron spectroscopy and photoluminescence spectroscopy revealed that the valence band maximum of the p-type Cu/Cu2 O matches well with the perovskite...
May 16, 2018: Scientific Reports
Matthew J Hamer, Endre Tóvári, Mengjian Zhu, Michael Dermot Thompson, Alexander S Mayorov, Jonathan Prance, Yongjin Lee, Richard Haley, Zakhar R Kudrynskyi, Amalia Patanè, Daniel Terry, Zakhar D Kovalyuk, Klaus Ensslin, Andrey V Kretinin, Andre K Geim, Roman Vladislavovich Gorbachev
Indium selenide, a post-transition metal chalcogenide, is a novel two-dimensional (2D) semiconductor with interesting electronic properties. Its tunable band gap and high electron mobility have already attracted considerable research interest. Here we demonstrate strong quantum confinement and manipulation of single electrons in devices made from few-layer crystals of InSe using electrostatic gating. We report on gate-controlled quantum dots in the Coulomb blockade regime as well as one-dimensional quantization in point contacts, revealing multiple plateaus...
May 15, 2018: Nano Letters
Junting Yu, Zhou Jiang, Yifan Hao, Qianhong Zhu, Mingliang Zhao, Xue Jiang, Jijun Zhao
Compared to inorganic solar cells, the power conversion efficiencies (PCEs) of organic solar cells are much lower, but they are compensated by many merits such as lower cost, less weight, and tunable structures, making them prospective for further applications. Porphyrin and phthalocyanine are the two most significant materials for organic solar cells due to their strong light-absorbing properties and semiconductor characteristics. However, there is little research on the 2D heterojunction solar cells based on these two materials, meanwhile the PCEs of them are still low...
May 15, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Francisco M Gómez-Campos, Salvador Rodríguez-Bolívar, Erik S Skibinsky-Gitlin, Marco Califano
We present a new non-stochastic framework for the calculation of the temperature dependence of the mobility in nanocrystal films, that enables speed-ups of several orders of magnitude compared to conventional Monte Carlo approaches, while maintaining a similar accuracy. Our model identifies a new contribution to the reduction of the mobility with increasing temperature in these systems (conventionally attributed to interactions with phonons), that alone is sufficient to explain the observed experimental trend up to room temperature...
May 15, 2018: Nanoscale
Yan-Ling Wang, Quan-Song Li, Ze-Sheng Li
Acceptor-π-donor-π-acceptor (A-π-D-π-A)-types of small molecules are very promising nonfullerene acceptors to overcome the drawbacks of fullerene derivatives such as the weak absorption ability and electronic adjustability. However, only few attempts have been made to develop π-bridge units to construct highly efficient acceptors in OSCs. Herein, taking the reported acceptor P1 as a reference, five small-structured acceptors (P2, P3, P4, P5, and P6) have been designed via the replacement of the π-bridge unit...
May 15, 2018: Physical Chemistry Chemical Physics: PCCP
Tiffany-Heather Ulep, Jeong-Yeol Yoon
Application of optically superior, tunable fluorescent nanotechnologies have long been demonstrated throughout many chemical and biological sensing applications. Combined with microfluidics technologies, i.e. on lab-on-a-chip platforms, such fluorescent nanotechnologies have often enabled extreme sensitivity, sometimes down to single molecule level. Within recent years there has been a peak interest in translating fluorescent nanotechnology onto paper-based platforms for chemical and biological sensing, as a simple, low-cost, disposable alternative to conventional silicone-based microfluidic substrates...
2018: Nano Convergence
Manabu Shiraishi, Daigo Shinoda, Nobu Yokoyama, Satoshi Itoh
A 49-year-old female was admitted to our hospital with a history of fever for 2 weeks and consciousness disorder.Transthoracic echocardiography demonstrated aortic regurgitation with a mobile fibrous band adhering to the right cusp. Infective endocarditis was diagnosed by positive blood culture and echocardiographic findings. Emergent aortic valve surgery was performed because of uncontrollable infection. A destroyed aortic annulus and subvalvular abscess was found during the operation. Removal of abscess tissue and annuloplasty with self-pericardium were successfully performed...
May 2018: Kyobu Geka. the Japanese Journal of Thoracic Surgery
Laura Ellen Birks, Benjamin Struchen, Marloes Eeftens, Luuk van Wel, Anke Huss, Peter Gajšek, Leeka Kheifets, Mara Gallastegi, Albert Dalmau-Bueno, Marisa Estarlich, Mariana F Fernandez, Inger Kristine Meder, Amparo Ferrero, Ana Jiménez-Zabala, Maties Torrent, Tanja G M Vrijkotte, Elisabeth Cardis, Jørn Olsen, Blaž Valič, Roel Vermeulen, Martine Vrijheid, Martin Röösli, Mònica Guxens
BACKGROUND: Exposure to radiofrequency electromagnetic fields (RF-EMF) has rapidly increased and little is known about exposure levels in children. This study describes personal RF-EMF environmental exposure levels from handheld devices and fixed site transmitters in European children, the determinants of this, and the day-to-day and year-to-year repeatability of these exposure levels. METHODS: Personal environmental RF-EMF exposure (μW/m2 , power flux density) was measured in 529 children (ages 8-18 years) in Denmark, the Netherlands, Slovenia, Switzerland, and Spain using personal portable exposure meters for a period of up to three days between 2014 and 2016, and repeated in a subsample of 28 children one year later...
May 10, 2018: Environment International
Mohammad Nabil Abo-Zeid, Samia M El-Gizawy, Noha N Atia, Salwa R El-Shaboury
Sofosbuvir (SOF) and daclatasvir (DCS) are newly discovered anti-hepatitis C drugs that have direct antiviral activity. A novel and simple high-performance thin-layer chromatography (HPTLC) method was designed for simultaneous determination of SOF and DCS in miscellaneous matrices. The method adopts coupling HPTLC with dual wavelength spectrodensitometry. Consequently, this enabled sensitive, specific and cost-effective determination of the SOF-DCS mixture. The developed HPTLC procedure is based on a simple liquid-liquid extraction, enrichment of the analytes and subsequent chromatographic separation with UV detection...
May 1, 2018: Journal of Pharmaceutical and Biomedical Analysis
Yajing Sun, Zhigang Shuai, Dong Wang
Few-layered arsenic-phosphorus alloys, AsxP(1-x), with a puckered structure have been recently synthesized and demonstrated with fully tunable band gaps and optical properties. It is predicted that the carrier mobility of monolayer AsP compounds is even higher than that of black phosphorene (b-P). The anisotropic and orthogonal electrical and thermal transport properties of the puckered group VA elements make them intriguing materials for thermoelectric applications. Herein, we investigated the thermal transport properties of AsP based on first-principles molecular dynamics and the Boltzmann transport equation...
May 10, 2018: Physical Chemistry Chemical Physics: PCCP
Anne Qvist Rasmussen, Niklas Rye Jørgensen, Peter Schwarz
The human calcium-sensing receptor ( CASR ) is the key controller of extracellular Cao 2+ homeostasis, and different mutations in the CASR gene have been linked to different calcium diseases, such as familial hypocalciuric hypercalcemia, severe hyperparathyroidism, autosomal-dominant hypocalcemia (ADH), and Bartter's syndrome type V. In this study, two generations of a family with biochemically and clinically confirmed ADH who suffered severe muscle pain, arthralgia, tetany, abdominal pain, and fatigue were evaluated for mutations in the CASR gene...
2018: Frontiers in Endocrinology
Antoine Lepicard, Flavie Bondu, Myungkoo Kang, Laura Sisken, Anupama Yadav, Frederic Adamietz, Vincent Rodriguez, Kathleen Richardson, Marc Dussauze
The potential for realizing robust, monolithic, near-surface refractive micro-optic elements with long-lived stability is demonstrated in visible and infrared transmitting glasses capable of use in dual band applications. Employing an enhanced understanding of glass chemistry and geometric control of mobile ion migration made possible with electrode patterning, flat, permanent, thermally-poled micro-optic structures have been produced and characterized. Sub-surface (t~5-10 µm) compositional and structural modification during the poling process results in formation of spatially-varying refractive index profiles, exhibiting induced Δn changes up to 5 × 10-2 which remain stable for >15 months...
May 9, 2018: Scientific Reports
Penghui He, CongBiao Jiang, Linfeng Lan, Sheng Sun, Yuzhi Li, Peixiong Gao, Peng Zhang, Xingqiang Dai, Jian Wang, Junbiao Peng, Yong Cao
Light-emitting filed-effect transistors (LEFETs) have attained great attention due to its special characteristic with both of the switching capacity and the electroluminescence capacity. However, high performance LEFETs with high mobility, high brightness and high efficiency have not been realized due to the difficulty in developing high electron and hole mobility materials with suitable band structures. In this paper, quantum-dot hybrid LEFETs (QD-HLEFETs) combined high luminous-efficiency quantum dots (QDs) and solution-processed scandium-incorporated indium oxide (Sc:In2O3) semiconductor were demonstrated...
May 9, 2018: ACS Nano
Jincheng Zhuang, Chen Liu, Qian Gao, Yani Liu, Haifeng Feng, Xun Xu, Jiaou Wang, Jijun Zhao, Shi Xue Dou, Zhenpeng Hu, Yi Du
Exploring stable two-dimensional materials with appropriate band gaps and high carrier mobility is highly desirable due to the potential applications in optoelectronic devices. Here, the electronic structures of phosphorene on Au(111) substrate are investigated by scanning tunneling spectroscopy, angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT) calculations. The substrate-induced phosphorene superstructure gives a superlattice potential, leading to a strong band folding effect of the sp band of Au(111) on the band structure...
May 9, 2018: ACS Nano
Xin Li, Junyou Yang, Qinghui Jiang, Hui Lai, Shuiping Li, Jiwu Xin, Weijing Chu, Jingdi Hou
For a typical perovskite solar cell (PKSC), electron transport layer (ETL) has a great effect on device performance and stability. In this paper, for the first time, we manifest that low-temperature solution-processed ZnSe can be used as a potential ETL for PKSCs. Our optimized device with ZnSe ETL has achieved high power conversion efficiency (PCE) of 17.78 % with negligible hysteresis, compared with the TiO2 based cell (13.76%). This enhanced photovoltaic performance is attributed the suitable band alignment, high electron mobility and reduced charge accumulation at the interface of ETL/perovskite...
May 9, 2018: ACS Nano
Xin Chen, Zhuo Wang, Lei Wang, Hai-Yu Wang, Yuan-Yuan Yue, Hai Wang, Xue-Peng Wang, Andrew T S Wee, Cheng-Wei Qiu, Hong-Bo Sun
Due to the large photoluminescence quantum yield, high mobility and good stability, organic super acid treated two-dimensional WSe2 has drawn much attention. However, reports about the influence of organic super acid treatment on the dynamic processes of excitons of monolayer WSe2 are still rare. In this work, through the broadband transient absorption spectra obtained using a femtosecond pump-probe system, we determine the dynamics of A' and C excitons in monolayer and bulk WSe2 at room temperature. Besides this, we also observe the relaxation process of the holes between the two spin split states in the valence band maximum in organic super acid treated monolayer WSe2...
May 8, 2018: Nanoscale
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