Showing papers by "Sungkyunkwan University published in 2014"

Solvent engineering for high-performance inorganic–organic hybrid perovskite solar cells

Abstract: The performance of solar cells based on organic–inorganic perovskites strongly depends on the device architecture and processing conditions. It is now shown that solvent engineering enables the deposition of very dense perovskite layers on mesoporous titania, leading to photovoltaic devices with a high light-conversion efficiency and no hysteresis.

Water photolysis at 12.3% efficiency via perovskite photovoltaics and Earth-abundant catalysts

Abstract: Although sunlight-driven water splitting is a promising route to sustainable hydrogen fuel production, widespread implementation is hampered by the expense of the necessary photovoltaic and photoelectrochemical apparatus. Here, we describe a highly efficient and low-cost water-splitting cell combining a state-of-the-art solution-processed perovskite tandem solar cell and a bifunctional Earth-abundant catalyst. The catalyst electrode, a NiFe layered double hydroxide, exhibits high activity toward both the oxygen and hydrogen evolution reactions in alkaline electrolyte. The combination of the two yields a water-splitting photocurrent density of around 10 milliamperes per square centimeter, corresponding to a solar-to-hydrogen efficiency of 12.3%. Currently, the perovskite instability limits the cell lifetime.

Growth of CH3NH3PbI3 cuboids with controlled size for high-efficiency perovskite solar cells.

Abstract: Perovskite solar cells with submicrometre-thick CH(3)NH(3)PbI(3) or CH(3)NH(3)PbI(3-x)Cl(x) active layers show a power conversion efficiency as high as 15%. However, compared to the best-performing device, the average efficiency was as low as 12%, with a large standard deviation (s.d.). Here, we report perovskite solar cells with an average efficiency exceeding 16% and best efficiency of 17%. This was enabled by the growth of CH(3)NH(3)PbI(3) cuboids with a controlled size via a two-step spin-coating procedure. Spin-coating of a solution of CH(3)NH(3)I with different concentrations follows the spin-coating of PbI(2), and the cuboid size of CH(3)NH(3)PbI(3) is found to strongly depend on the concentration of CH(3)NH(3)I. Light-harvesting efficiency and charge-carrier extraction are significantly affected by the cuboid size. Under simulated one-sun illumination, average efficiencies of 16.4% (s.d. ± 0.35), 16.3% (s.d. ± 0.44) and 13.5% (s.d. ± 0.34) are obtained from solutions of CH(3)NH(3)I with concentrations of 0.038 M, 0.050 M and 0.063 M, respectively. By controlling the size of the cuboids of CH(3)NH(3)PbI(3) during their growth, we achieved the best efficiency of 17.01% with a photocurrent density of 21.64 mA cm(-2), open-circuit photovoltage of 1.056 V and fill factor of 0.741.

Observation of high-energy astrophysical neutrinos in three years of icecube data

Abstract: A search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2012 provided the first evidence for a high-energy neutrino flux of extraterrestrial origin. Results from an analysis using the same methods with a third year (2012-2013) of data from the complete IceCube detector are consistent with the previously reported astrophysical flux in the 100 TeV-PeV range at the level of 10(-8) GeV cm(-2) s(-1) sr(-1) per flavor and reject a purely atmospheric explanation for the combined three-year data at 5.7 sigma. The data are consistent with expectations for equal fluxes of all three neutrino flavors and with isotropic arrival directions, suggesting either numerous or spatially extended sources. The three-year data set, with a live time of 988 days, contains a total of 37 neutrino candidate events with deposited energies ranging from 30 to 2000 TeV. The 2000-TeV event is the highest-energy neutrino interaction ever observed.

Ultrasensitive mechanical crack-based sensor inspired by the spider sensory system

Abstract: Recently developed flexible mechanosensors based on inorganic silicon, organic semiconductors, carbon nanotubes, graphene platelets, pressure-sensitive rubber and self-powered devices are highly sensitive and can be applied to human skin. However, the development of a multifunctional sensor satisfying the requirements of ultrahigh mechanosensitivity, flexibility and durability remains a challenge. In nature, spiders sense extremely small variations in mechanical stress using crack-shaped slit organs near their leg joints. Here we demonstrate that sensors based on nanoscale crack junctions and inspired by the geometry of a spider's slit organ can attain ultrahigh sensitivity and serve multiple purposes. The sensors are sensitive to strain (with a gauge factor of over 2,000 in the 0-2 per cent strain range) and vibration (with the ability to detect amplitudes of approximately 10 nanometres). The device is reversible, reproducible, durable and mechanically flexible, and can thus be easily mounted on human skin as an electronic multipixel array. The ultrahigh mechanosensitivity is attributed to the disconnection-reconnection process undergone by the zip-like nanoscale crack junctions under strain or vibration. The proposed theoretical model is consistent with experimental data that we report here. We also demonstrate that sensors based on nanoscale crack junctions are applicable to highly selective speech pattern recognition and the detection of physiological signals. The nanoscale crack junction-based sensory system could be useful in diverse applications requiring ultrahigh displacement sensitivity.

Parameters Affecting I-V Hysteresis of CH3NH3PbI3 Perovskite Solar Cells: Effects of Perovskite Crystal Size and Mesoporous TiO2 Layer.

Abstract: Current–voltage (I–V) characteristics of CH3NH3PbI3 perovskite solar cells are studied using a time-dependent current response with stepwise sweeping of the bias voltage. Compared with the crystalline Si solar cell showing time-independent current at a given bias voltage, the perovskite solar cells exhibit time-dependent current response. The current increases with time and becomes steady at forward scan from short-circuit to open-circuit, whereas it is decayed and saturated with time at reverse scan from open-circuit to short-circuit. Time-dependent current response eventually leads to I–V hysteresis depending on the scan direction and the scan rate. Crystal size of CH3NH3PbI3 and the mesoporous TiO2 (mp-TiO2) film are found to influence I–V hysteresis, where the I–V hysteresis is alleviated as crystal size increases and in the presence of mp-TiO2. The capacitance observed at low frequency (0.1 to 1 Hz), associated with dipole polarization, tends to diminish as size of perovskite and mp-TiO2 layer thickn...

Wafer-Scale Growth of Single-Crystal Monolayer Graphene on Reusable Hydrogen-Terminated Germanium

Abstract: The uniform growth of single-crystal graphene over wafer-scale areas remains a challenge in the commercial-level manufacturability of various electronic, photonic, mechanical, and other devices based on graphene. Here, we describe wafer-scale growth of wrinkle-free single-crystal monolayer graphene on silicon wafer using a hydrogen-terminated germanium buffer layer. The anisotropic twofold symmetry of the germanium (110) surface allowed unidirectional alignment of multiple seeds, which were merged to uniform single-crystal graphene with predefined orientation. Furthermore, the weak interaction between graphene and underlying hydrogen-terminated germanium surface enabled the facile etch-free dry transfer of graphene and the recycling of the germanium substrate for continual graphene growth.

High-efficiency perovskite solar cells based on the black polymorph of HC(NH2)2 PbI3.

Abstract: Perovskite solar cells with power conversion efficiencies exceeding 16% at AM 15 G one sun illumination are developed using the black polymorph of formamidnium lead iodide, HC(NH2)2 PbI3 Compared with CH3 NH3 PbI3 , HC(NH2 )2 PbI3 extends its absoprtion to 840 nm and shows no phase transition between 296 and 423 K Moreover, a solar cell based on HC(NH2 )2 PbI3 exhibits photostability and little I-V hysteresis

Length-dependent thermal conductivity in suspended single-layer graphene.

Abstract: Graphene exhibits extraordinary electronic and mechanical properties, and extremely high thermal conductivity. Being a very stable atomically thick membrane that can be suspended between two leads, graphene provides a perfect test platform for studying thermal conductivity in two-dimensional systems, which is of primary importance for phonon transport in low-dimensional materials. Here we report experimental measurements and nonequilibrium molecular dynamics simulations of thermal conduction in suspended single-layer graphene as a function of both temperature and sample length. Interestingly and in contrast to bulk materials, at 300 K, thermal conductivity keeps increasing and remains logarithmically divergent with sample length even for sample lengths much larger than the average phonon mean free path. This result is a consequence of the two-dimensional nature of phonons in graphene, and provides fundamental understanding of thermal transport in two-dimensional materials.

o-Methoxy Substituents in Spiro-OMeTAD for Efficient Inorganic–Organic Hybrid Perovskite Solar Cells

Abstract: Three spiro-OMeTAD derivatives have been synthesized and characterized by (1)H/(13)C NMR spectroscopy and mass spectrometry The optical and electronic properties of the derivatives were modified by changing the positions of the two methoxy substituents in each of the quadrants, as monitored by UV-vis spectroscopy and cyclic voltammetry measurements The derivatives were employed as hole-transporting materials (HTMs), and their performances were compared for the fabrication of mesoporous TiO2/CH3NH3PbI3/HTM/Au solar cells Surprisingly, the cell performance was dependent on the positions of the OMe substituents The derivative with o-OMe substituents showed highly improved performance by exhibiting a short-circuit current density of 212 mA/cm(2), an open-circuit voltage of 102 V, and a fill factor of 776% under 1 sun illumination (100 mW/cm(2)), which resulted in an overall power conversion efficiency (PCE) of 167%, compared to ~15% for conventional p-OMe substituents The PCE of 167% is the highest value reported to date for perovskite-based solar cells with spiro-OMeTAD

Voltage output of efficient perovskite solar cells with high open-circuit voltage and fill factor

Abstract: Besides the generated photocurrent as a key factor that impacts the efficiency of solar cells, the produced photovoltage and fill factor are also of critical importance. Therefore, understanding and optimization of the open-circuit voltage (Voc) of perovskite solar cells, especially with an architecture consisting of mesoporous (mp)-TiO2/perovskite/hole transporting materials (HTMs), are required to further improve the conversion efficiency. In this work, we study the effects of the energy level between CH3NH3(= MA)PbI3 and MAPbBr3 and a series of triarylamine polymer derivatives containing fluorene and indenofluorene, which have different highest occupied molecular orbital (HOMO) levels, in terms of the photovoltaic behaviour. The voltage output of the device is found to be dependent on the higher energy level of perovskite solar absorbers as well as the HOMO level of the HTMs. The combination of MAPbBr3 and a deep-HOMO HTM leads to a high photovoltage of 1.40 V, with a fill factor of 79% and an energy conversion efficiency of up to 6.7%, which is the highest value reported to date for MAPbBr3 perovskite solar cells.

Organolead Halide Perovskite: New Horizons in Solar Cell Research

Abstract: Organolead-halide-perovskite-based solar cells have recently received significant attention due to their excellent photovoltaic performance and low cost. The general formula of this perovskite light harvester is RPbX3, where R and X stand for a monovalent organic cation and halide anion, respectively. Structures of the perovskite solar cell are designed based on the function of the perovskite. Organolead halide perovskites can be used either as sensitizers or n- or p-type light harvesters. Rapid progress has been made over the past year since the first report on long-term, durable, 9.7% efficiency perovskite solar cells based on CH3NH3PbI3-sensitized TiO2 in 2012. As a result, power conversion efficiencies as high as 16% have been achieved. Further improvement is expected from this material in terms of understanding charge accumulation and transport properties. Organolead halide perovskite is now regarded as a promising solar cell material, opening new horizons in solar cell research.

Slow dynamic processes in lead halide perovskite solar cells. Characteristic times and hysteresis

Abstract: Characteristic times of perovskite solar cells (PSCs) have been measured by different techniques: transient photovoltage decay, transient photoluminescence, and impedance spectroscopy. A slow dynamic process is detected that shows characteristic times in the seconds to milliseconds scale, with good quantitative agreement between transient photovoltage decay and impedance spectroscopy. Here, we show that this characteristic time is related with a novel slow dynamic process caused by the peculiar structural properties of lead halide perovskites and depending on perovskite crystal size and organic cation nature. This new process may lie at the basis of the current–voltage hysteresis reported for PSCs and could have important implications in PSC performance because it may give rise to distinct dynamical behavior with respect to other classes of photovoltaic devices. Furthermore, we show that low-frequency characteristic time, commonly associated with electronic carrier lifetime in other photovoltaic devices, ...

11% Efficient Perovskite Solar Cell Based on ZnO Nanorods: An Effective Charge Collection System

Abstract: A perovskite solar cell based on ZnO nanorods was prepared, and its photovoltaic performance was investigated. ZnO nanorods were grown on the ZnO seed layer from solution, and their diameters and lengths were controlled by precursor concentration and growth time. CH3NH3PbI3 perovskite infiltrated ZnO nanorods showed a power conversion efficiency of 11.13% with short-circuit current density Jsc of 20.08 mA/cm2, open-circuit voltage Voc of 991 mV and fill factor of 0.56. Square spectral feature of external quantum efficiency (EQE) was observed, where EQE exceeded 80% in almost the entire wavelength range from 400 to 750 nm, and the integrated current density of 20.03 mA/cm2 calculated from EQE data was in good agreement with the observed Jsc. Compared to the perfect spectral response of ZnO nanorods, a perovskite solar cell based on TiO2 nanorods exhibited an integrated current density (16 mA/cm2) much lower than the measured Jsc (20.9 mA/cm2). In addition, time-limited photocurrent response under 530 and 7...

Benefits of very thin PCBM and LiF layers for solution-processed p–i–n perovskite solar cells

Abstract: Highly efficient p–i–n perovskite solar cells employing a flat and thick CH3NH3PbI3 film and a thin PCBM film are fabricated by the solution-process at low temperature. Through attainment of optimized PCBM thickness and insertion of the LiF interlayer, the unit cell shows 14.1% of overall power conversion efficiency (PCE) with a Jsc of 20.7 mA cm−2, a Voc of 0.866 V, and a FF of 78.3% under AM 1.5G 100 mW cm−2 conditions, while a larger area 10 cell serially connected module (10 × 10 cm2) shows an 8.7% PCE. These PCE values are the highest reported to date for the planar perovskite–PCBM solar cells.

Autophagy--a key player in cellular and body metabolism.

Abstract: Knowledge gained over the past 10 years about the mechanisms that underpin autophagy has provided a universal framework for studies of diverse physiological and pathological processes. Of particular interest is the emerging role of autophagy in the maintenance of energy homeostasis, both at the cellular level and within the organism as a whole. Dysregulation of autophagy might contribute to the development of metabolic disorders, including insulin resistance, diabetes mellitus, obesity, atherosclerosis and osteoporosis. The authors of this Review highlight research findings on the regulation of cellular autophagy by nutrients. They also describe the role of autophagy in various tissues in the regulation of energy metabolism and the development of diseases related to altered metabolism. Finally, the potential of pharmacological modulation of autophagy as a treatment for human metabolic disorders is discussed.

Description and performance of track and primary-vertex reconstruction with the CMS tracker

Abstract: A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tt events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of p_T > 0.9GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p_T = 100GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in p_T, and respectively, 10μm and 30μm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10–12μm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung.

Association of Non-Alcoholic Fatty Liver Disease With Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Abstract: Background: Chronic kidney disease (CKD) is a frequent, under-recognized condition and a risk factor for renal failure and cardiovascular disease. Increasing evidence connects non-alcoholic fatty liver disease (NAFLD) to CKD. We conducted a meta-analysis to determine whether the presence and severity of NAFLD are associated with the presence and severity of CKD. Methods and Findings: English and non-English articles from international online databases from 1980 through January 31, 2014 were searched. Observational studies assessing NAFLD by histology, imaging, or biochemistry and defining CKD as either estimated glomerular filtration rate (eGFR) ,60 ml/min/1.73 m 2 or proteinuria were included. Two reviewers extracted studies independently and in duplicate. Individual participant data (IPD) were solicited from all selected studies. Studies providing IPD were combined with studies providing only aggregate data with the two-stage method. Main outcomes were pooled using random-effects models. Sensitivity and subgroup analyses were used to explore sources of heterogeneity and the effect of potential confounders. The influences of age, whole-body/abdominal obesity, homeostasis model of insulin resistance (HOMA-IR), and duration of follow-up on effect estimates were assessed by meta-regression. Thirty-three studies (63,902 participants, 16 population-based and 17 hospital-based, 20 cross-sectional, and 13 longitudinal) were included. For 20 studies (61% of included studies, 11 cross-sectional and nine longitudinal, 29,282 participants), we obtained IPD. NAFLD was associated with an increased risk of prevalent (odds ratio [OR] 2.12, 95% CI 1.69– 2.66) and incident (hazard ratio [HR] 1.79, 95% CI 1.65–1.95) CKD. Non-alcoholic steatohepatitis (NASH) was associated with a higher prevalence (OR 2.53, 95% CI 1.58–4.05) and incidence (HR 2.12, 95% CI 1.42–3.17) of CKD than simple steatosis. Advanced fibrosis was associated with a higher prevalence (OR 5.20, 95% CI 3.14–8.61) and incidence (HR 3.29, 95% CI 2.30– 4.71) of CKD than non-advanced fibrosis. In all analyses, the magnitude and direction of effects remained unaffected by diabetes status, after adjustment for other risk factors, and in other subgroup and meta-regression analyses. In crosssectional and longitudinal studies, the severity of NAFLD was positively associated with CKD stages. Limitations of analysis are the relatively small size of studies utilizing liver histology and the suboptimal sensitivity of ultrasound and biochemistry for NAFLD detection in population-based studies. Conclusion: The presence and severity of NAFLD are associated with an increased risk and severity of CKD. Please see later in the article for the Editors’ Summary.

Lateral MoS2 p-n junction formed by chemical doping for use in high-performance optoelectronics.

Abstract: This paper demonstrates a technique to form a lateral homogeneous 2D MoS2 p–n junction by partially stacking 2D h-BN as a mask to p-dope MoS2. The fabricated lateral MoS2 p–n junction with asymmetric electrodes of Pd and Cr/Au displayed a highly efficient photoresponse (maximum external quantum efficiency of ∼7000%, specific detectivity of ∼5 × 1010 Jones, and light switching ratio of ∼103) and ideal rectifying behavior. The enhanced photoresponse and generation of open-circuit voltage (VOC) and short-circuit current (ISC) were understood to originate from the formation of a p–n junction after chemical doping. Due to the high photoresponse at low VD and VG attributed to its built-in potential, our MoS2 p–n diode made progress toward the realization of low-power operating photodevices. Thus, this study suggests an effective way to form a lateral p–n junction by the h-BN hard masking technique and to improve the photoresponse of MoS2 by the chemical doping process.

Measurement of the properties of a Higgs boson in the four-lepton final state

Abstract: Austrian Federal Ministry of Science and Research and the Austrian Science Fund; the Belgian Fonds de la Recherche Scientifique and Fonds voor Wetenschappelijk Onderzoek; the Brazilian Funding Agencies (CNPq, CAPES, FAPERJ, and FAPESP); the Bulgarian Ministry of Education and Science; CERN; the Chinese Academy of Sciences, Ministry of Science and Technology, and National Natural Science Foundation of China; the Colombian Funding Agency (COLCIENCIAS); the Croatian Ministry of Science, Education and Sport, and the Croatian Science Foundation; the Research Promotion Foundation, Cyprus; the Ministry of Education and Research, Recurrent Financing Contract No. SF0690030s09 and European Regional Development Fund, Estonia; the Academy of Finland, Finnish Ministry of Education and Culture, and Helsinki Institute of Physics; the Institut National de Physique Nucleaire et de Physique des Particules/CNRS and Commissariat a l’Energie Atomique et aux Energies Alternatives/CEA, France; the Bundesministerium fur Bildung und Forschung, Deutsche Forschungsgemeinschaft, and Helmholtz-Gemeinschaft Deutscher Forschungszentren, Germany; the General Secretariat for Research and Technology, Greece; the National Scientific Research Foundation and National Innovation Office, Hungary; the Department of Atomic Energy and the Department of Science and Technology, India; the Institute for Studies in Theoretical Physics and Mathematics, Iran; the Science Foundation, Ireland; the Istituto Nazionale di Fisica Nucleare, Italy; the Korean Ministry of Education, Science and Technology and the World Class University program of NRF, Republic of Korea; the Lithuanian Academy of Sciences; the Mexican Funding Agencies (CINVESTAV, CONACYT, SEP, and UASLP-FAI); the Ministry of Business, Innovation and Employment, New Zealand; the Pakistan Atomic Energy Commission; the Ministry of Science and Higher Education and the National Science Centre, Poland; the Fundacao para a Ciencia e a Tecnologia, Portugal; JINR, Dubna, the Ministry of Education and Science of the Russian Federation, the Federal Agency of Atomic Energy of the Russian Federation, Russian Academy of Sciences, and the Russian Foundation for Basic Research; the Ministry of Education, Science and Technological Development of Serbia; the Secretaria de Estado de Investigacion, Desarrollo e Innovacion and Programa Consolider-Ingenio 2010, Spain; the Swiss Funding Agencies (ETH Board, ETH Zurich, PSI, SNF, UniZH, Canton Zurich, and SER); the National Science Council, Taipei; the Thailand Center of Excellence in Physics, the Institute for the Promotion of Teaching Science and Technology of Thailand, Special Task Force for Activating Research and the National Science and Technology Development Agency of Thailand; the Scientific and Technical Research Council of Turkey and the Turkish Atomic Energy Authority; the Science and Technology Facilities Council, United Kingdom; the U.S. Department of Energy and the U.S. National Science Foundation.Individuals have received support from the Marie-Curie program and the European Research Council and EPLANET (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation a la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS programme of Foundation for Polish Science, cofinanced by EU, Regional Development Fund; and the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF.

Thermal Behavior of Methylammonium Lead- trihalide Perovskite Photovoltaic Light Harvesters

Abstract: Recently organic–inorganic hybrid perovskites have attracted attention as light harvesting materials in mesoscopic cells. While a considerable number of deposition and formation methods have been reported for the perovskite crystalline material, most involve an annealing step. As such, the thermal behavior of this material and its individual components is of crucial interest. Here, we examine the thermal properties of the CH3NH3PbX3 (X = I or Cl) perovskite using thermogravimetric analysis. The role of the precursors is exposed, and the effect of the formation of excess organic species is investigated. The sublimation behavior of the organic component is intensively scrutinized. Furthermore, differential scanning calorimetry is employed to probe the crystal phase structure, revealing subtle differences depending on the deposition method.

Observation of the diphoton decay of the Higgs boson and measurement of its properties

Abstract: Observation of the diphoton decay mode of the recently discovered Higgs boson and measurement of some of its properties are reported. The analysis uses the entire dataset collected by the CMS experiment in proton-proton collisions during the 2011 and 2012 LHC running periods. The data samples correspond to integrated luminosities of 5.1 inverse femtobarns at sqrt(s) = 7 TeV and 19.7 inverse femtobarns at 8 TeV. A clear signal is observed in the diphoton channel at a mass close to 125 GeV with a local significance of 5.7 sigma, where a significance of 5.2 sigma is expected for the standard model Higgs boson. The mass is measured to be 124.70 +/- 0.34 GeV = 124.70 +/- 0.31 (stat) +/- 0.15 (syst) GeV, and the best-fit signal strength relative to the standard model prediction is 1.14 +0.26/-0.23 = 1.14 +/- 0.21 (stat) +0.09/-0.05 (syst) +0.13/-0.09 (theo). Additional measurements include the signal strength modifiers associated with different production mechanisms, and hypothesis tests between spin-0 and spin-2 models.

Highly stretchable piezoelectric-pyroelectric hybrid nanogenerator.

Abstract: A highly stretchable hybrid nanogenerator has been developed using a micro-patterned piezoelectric polymer P(VDF-TrFE), PDMS-CNT composite, and graphene nanosheets. Mechanical and thermal energies are simultaneously harvested from a single cell of the device. The hybrid nanogenerator exhibits high robustness behavior even after 30% stretching and generates very stable piezoelectric and pyroelectric power outputs due to micro-pattern designing.

Background and Data Configuration Process of a Nationwide Population-Based Study Using the Korean National Health Insurance System

Abstract: Background: The National Health Insurance Service (NHIS) recently signed an agreement to provide limited open access to the databases within the Korean Diabetes Association for the benefit of Korean subjects with diabetes Here, we present the history, structure, contents, and way to use data procurement in the Korean National Health Insurance (NHI) system for the benefit of Korean researchers Methods: The NHIS in Korea is a single-payer program and is mandatory for all residents in Korea The three main healthcare programs of the NHI, Medical Aid, and long-term care insurance (LTCI) provide 100% coverage for the Korean population The NHIS in Korea has adopted a fee-for-service system to pay health providers Researchers can obtain health information from the four databases of the insured that contain data on health insurance claims, health check-ups and LTCI Results: Metabolic disease as chronic disease is increasing with aging society NHIS data is based on mandatory, serial population data, so, this might show the time course of disease and predict some disease progress, and also be used in primary and secondary prevention of disease after data mining Conclusion: The NHIS database represents the entire Korean population and can be used as a population-based database The integrated information technology of the NHIS database makes it a world-leading population-based epidemiology and disease research platform

Highly improved Sb2S3 sensitized-inorganic-organic heterojunction solar cells and quantification of traps by deep-level transient spectroscopy

Abstract: The light-harvesting Sb2S3 surface on mesoporous-TiO2 in inorganic–organic heterojunction solar cells is sulfurized with thioacetamide (TA). The photovoltaic performances are compared before and after TA treatment, and the state of the Sb2S3 is investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and deep-level transient spectroscopy (DLTS). Although there are no differences in crystallinity and composition, the TA-treated solar cells exhibit significantly enhanced performance compared to pristine Sb2S3-sensitized solar cells. From DLTS analysis, the performance enhancement is mainly attributed to the extinction of trap sites, which are present at a density of (2–5) × 1014 cm−3 in Sb2S3, by TA treatment. Through such a simple treatment, the cell records an overall power conversion efficiency (PCE) of 7.5% through a metal mask under simulated illumination (AM 1.5G, 100 mW cm–2) with a very high open circuit voltage of 711.0 mV. This PCE is, thus far, the highest reported for fully solid-state chalcogenide-sensitized solar cells.

The Physics of the B Factories

Abstract: This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C.

Hydrophobic Sponge Structure-Based Triboelectric Nanogenerator

Abstract: Hydrophobic sponge structure-based triboelectric nanogenerators using an inverse opal structured film for sustainable energy harvesting over a wide range of humid atmosphere have been successfully demonstrated. The output voltage and current density reach a record value of 130 V and 0.10 mA cm(-2) , respectively, giving over 10-fold power enhancement, compared with the flat film-based triboelectric nanogenerator.