Showing papers by "Yang Yang published in 2012"
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TL;DR: In this article, a review summarizes recent progress in the development of polymer solar cells and provides a synopsis of major achievements in the field over the past few years, while potential future developments and the applications of this technology are also briefly discussed.
Abstract: This Review summarizes recent progress in the development of polymer solar cells. It covers the scientific origins and basic properties of polymer solar cell technology, material requirements and device operation mechanisms, while also providing a synopsis of major achievements in the field over the past few years. Potential future developments and the applications of this technology are also briefly discussed.
3,832 citations
TL;DR: In this paper, the authors demonstrate that PBDTT-DPP, a semiconducting polymer with a low bandgap of 1.44 eV, allows tandem polymer solar cells to reach power conversion efficiencies of around 8.6%.
Abstract: Researchers demonstrate that PBDTT-DPP, a semiconducting polymer with a low bandgap of 1.44 eV, allows tandem polymer solar cells to reach power conversion efficiencies of around 8.6%.
1,406 citations
TL;DR: The use of two metallic nanostructures to achieve broad light absorption enhancement, increased shortcircuit current, and improved fi ll factor ( FF) simultaneously based on the new small-bandgap polymer donor poly{[4,8-bis(2-ethyl-hexyl-thiophene-5-yl)-benzo[1,2-b:4,5-b ′ ]dithiophene2,6-diyl]alt -[2-(2
Abstract: Polymer-fullerene-based bulk heterojunction (BHJ) solar cells have many advantages, including low-cost, low-temperature fabrication, semi-transparency, and mechanical fl exibility. [ 1 , 2 ] However, there is a mismatch between optical absorption length and charge transport scale. [ 3 , 4 ] These factors lead to recombination losses, higher series resistances, and lower fi ll factors. Attempts to optimize both the optical and electrical properties of the photoactive layer in organic solar cells (OSCs) inevitably result in a demand to develop a device architecture that can enable effi cient optical absorption in fi lms thinner than the optical absorption length. [ 5 , 6 ] Here, we report the use of two metallic nanostructures to achieve broad light absorption enhancement, increased shortcircuit current ( J sc ), and improved fi ll factor ( FF ) simultaneously based on the new small-bandgap polymer donor poly{[4,8-bis(2-ethyl-hexyl-thiophene-5-yl)-benzo[1,2-b:4,5-b ′ ]dithiophene2,6-diyl]alt -[2-(2 ′ -ethyl-hexanoyl)-thieno[3,4-b]thiophen-4,6-diyl]} (PBDTTT-C-T) in BHJ cells. [ 7 ] The dual metallic nanostructure consists of a metallic nanograting electrode as the back refl ector and metallic nanoparticles (NPs) embedded in the active layer. Consequently, we achieve the high power conversion effi ciency (PCE) of 8.79% for a single-junction BHJ OSC. Recently, plasmonic nanostructures have been introduced into solar cells for highly effi cient light harvesting. [ 5 , 8–17 ] Two types of plasmonic resonances, surface plasmonic resonances (SPRs) [ 18–22 ] and localized plasmonic resonances (LPRs), [ 11–14 ] can be used for enhancing light absorption. Metallic gratingbased light-trapping schemes have been investigated in traditional inorganic photovoltaic cells. [ 18–20 ] For metallic nanogratings, which can support SPRs, it is still challenging to experimentally demonstrate the enhancement of PCE in OSCs owing to the obvious issue of solution processing of
678 citations
TL;DR: High-performance, visibly transparent polymer solar cells fabricated via solution processing are demonstrated, which harvests solar energy from the near-infrared region while being less sensitive to visible photons.
Abstract: Visibly transparent photovoltaic devices can open photovoltaic applications in many areas, such as building-integrated photovoltaics or integrated photovoltaic chargers for portable electronics. We demonstrate high-performance, visibly transparent polymer solar cells fabricated via solution processing. The photoactive layer of these visibly transparent polymer solar cells harvests solar energy from the near-infrared region while being less sensitive to visible photons. The top transparent electrode employs a highly transparent silver nanowire–metal oxide composite conducting film, which is coated through mild solution processes. With this combination, we have achieved 4% power-conversion efficiency for solution-processed and visibly transparent polymer solar cells. The optimized devices have a maximum transparency of 66% at 550 nm.
527 citations
TL;DR: Low bandgap polymers prepared using BDTT, BDTP, FDPP, and DPP units via Stille-coupling polymerization lead to polymers with different optical, electrochemical, and electronic properties that have great potential for high efficiency tandem polymer solar cells.
Abstract: The tandem solar cell architecture is an effective way to harvest a broader part of the solar spectrum and make better use of the photonic energy than the single junction cell. Here, we present the design, synthesis, and characterization of a series of new low bandgap polymers specifically for tandem polymer solar cells. These polymers have a backbone based on the benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) units. Alkylthienyl and alkylphenyl moieties were incorporated onto the BDT unit to form BDTT and BDTP units, respectively; a furan moiety was incorporated onto the DPP unit in place of thiophene to form the FDPP unit. Low bandgap polymers (bandgap = 1.4-1.5 eV) were prepared using BDTT, BDTP, FDPP, and DPP units via Stille-coupling polymerization. These structural modifications lead to polymers with different optical, electrochemical, and electronic properties. Single junction solar cells were fabricated, and the polymer:PC(71)BM active layer morphology was optimized by adding 1,8-diiodooctane (DIO) as an additive. In the single-layer photovoltaic device, they showed power conversion efficiencies (PCEs) of 3-6%. When the polymers were applied in tandem solar cells, PCEs over 8% were reached, demonstrating their great potential for high efficiency tandem polymer solar cells.
514 citations
TL;DR: Inverted polymer solar cells have been developed and continue to grow particularly due to their potential for superior device stability and manufacturing compatibility.
Abstract: Polymer solar cells have many advantages, including transparency, aesthetically pleasing, fl exibility, and light weight. They are particularly compatible with high throughput and low-cost fabrication processes, which make them a promising photovoltaic technology. [ 1–5 ] These properties enable a wide range of potential applications, even for outer space. [ 6 , 7 ] In the last few years, many high-performance polymers with high solar-cell effi ciency have been reported. [ 8–16 ] Among those, benzodithiophene (BDT) and thionothiophene (TT)-based polymers were the fi rst polymer family to break the 7% and 8% effi ciency barriers. [ 8–12 ] Poly{2,6 ′ -4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,4-b] dithiophenealt -5-dibutyloctyl-3,6-bis(5-bromothiophen-2-yl) pyrrolo[3,4-c]pyrrole-1,4-dione} (PBDTT-DPP) with a lower bandgap ( ≈ 1.4 eV) showed superior performance in long wavelength regions, which enabled signifi cant progress in tandem solar cells with effi ciency close to 9%. [ 14 ] For historical reasons, these high-effi ciency low-bandgap polymers were mostly evaluated based on standard structures, typically with poly(3,4-ethy lenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a hole-transport layer (HTL) and a low-work-function metal such as Ca as the electron-transport layer (ETL). Inverted polymer solar cells have been developed and continue to grow particularly due to their potential for superior device stability and manufacturing compatibility. [ 17–24 ] In the inverted architecture with the classical poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) active layer, several successful n -type buffer layers such as cesium carbonate (Cs 2 CO 3 ), [ 17 ] titanium oxide (TiO 2 ), [ 22 ] Cs-doped TiO 2 , [ 25 ] zinc oxide (ZnO), [ 18 ] and a combination of ZnO and self-assembled monolayers [ 19 ] have been shown to be able to alter the carrier selectivity of the indium tin oxide (ITO) electrode and convert it to a cathode contact. On the anode side, the most widely used are transition metal oxides
339 citations
TL;DR: An MoO(3) film spin-coated from a solution prepared by an extremely facile and cost-effective synthetic method is introduced as an anode buffer layer of bulk-heterojunction polymer photovoltaic devices.
Abstract: An MoO(3) film spin-coated from a solution prepared by an extremely facile and cost-effective synthetic method is introduced as an anode buffer layer of bulk-heterojunction polymer photovoltaic devices. The device efficiency using the MoO(3) anode buffer layer is comparable to that using a conventional PEDOT:PSS layer without annealing at an elevated temperature.
295 citations
TL;DR: In this article, drift-diffusion simulations with experiments are compared to explore the influence and the detection limit of doping in situations where device thickness and doping density are too low for the depletion approximation to be valid, and the results of the simulations suggest that the typically measured values on the order of 5 × 1016 cm-3 for doping density in thin films of 100 nm or lower may not be reliably determined from capacitance measurements and could originate from a completely intrinsic active layer.
Abstract: The application of Mott–Schottky analysis to capacitance–voltage measurements of polymer:fullerene solar cells is a frequently used method to determine doping densities and built-in voltages, which have important implications for understanding the device physics of these cells. Here we compare drift-diffusion simulations with experiments to explore the influence and the detection limit of doping in situations where device thickness and doping density are too low for the depletion approximation to be valid. The results of our simulations suggest that the typically measured values on the order of 5 × 1016 cm–3 for doping density in thin films of 100 nm or lower may not be reliably determined from capacitance measurements and could originate from a completely intrinsic active layer. In addition, we explain how the violation of the depletion approximation leads to a strong underestimation of the actual built-in voltage by the built-in voltage VMS determined by Mott–Schottky analysis.
251 citations
TL;DR: Electrical measurements from graphene field-effect transistors show that the B-doped graphenes have a distinct p-type conductivity with a current on/off ratio higher than 10(2) with a series of modulated transport properties.
Abstract: We report tunable band gaps and transport properties of B-doped graphenes that were achieved via controllable doping through reaction with the ion atmosphere of trimethylboron decomposed by microwave plasma. Both electron energy loss spectroscopy and X-ray photoemission spectroscopy analyses of the graphene reacted with ion atmosphere showed that B atoms are substitutionally incorporated into graphenes without segregation of B domains. The B content was adjusted over a range of 0–13.85 atom % by controlling the ion reaction time, from which the doping effects on transport properties were quantitatively evaluated. Electrical measurements from graphene field-effect transistors show that the B-doped graphenes have a distinct p-type conductivity with a current on/off ratio higher than 102. Especially, the band gap of graphenes is tuned from 0 to ∼0.54 eV with increasing B content, leading to a series of modulated transport properties. We believe the controllable doping for graphenes with predictable transport...
223 citations
TL;DR: A novel solution-based approach is presented to process earth-abundant Cu(2)ZnSn(S,Se)(4) absorbers using fully dissolved CZTS precursors in which each of the elemental constituents intermix on a molecular scale to enable low-temperature processing of chemically clean kesterite films with excellent homogeneity.
Abstract: A novel solution-based approach is presented to process earth-abundant Cu(2)ZnSn(S,Se)(4) absorbers using fully dissolved CZTS precursors in which each of the elemental constituents intermix on a molecular scale This method enables the low-temperature processing of chemically clean kesterite films with excellent homogeneity The high performance of resulting optoelectronic devices represents a chance to extend the impact of CZTS into the next chapter of thin-film solar cells
198 citations
TL;DR: In this article, the effect of surface coating on the specific absorption rate (SAR) under an alternating magnetic field was investigated and ascribed to the increased Brownian loss, improved thermal conductivity as well as improved dispersibility.
Abstract: Highly monodispersed magnetite nanoparticles with controlled particle size and mPEG surface coating have been successfully synthesized as a model system to investigate the effect of surface coating on the specific absorption rate (SAR) under an alternating magnetic field. Enhanced SAR with decreased surface coating thickness was observed and ascribed to the increased Brownian loss, improved thermal conductivity as well as improved dispersibility. By elaborate optimization of the surface coating and particle size, a significant increase of SAR (up to 74%) could be achieved with a minimal variation of the saturation magnetization (<5%). In particular, the 19nm@2000 sample exhibited the highest SAR of 930 W g−1 among the samples. Furthermore, this high heating capacity can be maintained in various simulated physiological conditions. Our results provide a general strategy for surface coating optimization of magnetic cores for high performance hyperthermia agents.
TL;DR: In this paper, a low bandgap polymer benzodithiophene polymers (PTB7) is used to demonstrate the surface plasmonic effects of large-area metallic nanostructures.
Abstract: Polymer solar cells hold the promise for a cost-effective, lightweight solar energy conversion platform, which can benefi t from simple solution processing of the active layer. [ 1–3 ] At present, bulk hetero-junction polymer solar cells show power conversion effi ciency (PCE) close to or over than 8%. [ 4–10 ] However, the quantum effi ciency of polymer solar cells is mainly limited due to the comparatively low carrier mobility and charge recombination. [ 1–3 ] A thinner active layer can lower the probability of charge recombination and increase the carrier drift velocity by having higher electric fi eld, thus enhancing the internal quantum effi ciency, while a minimum fi lm thickness is always required to ensure suffi cient photon absorption. [ 11 , 12 ] Therefore, how to increase the light absorption of a polymer fi lm at a limited thickness of fi lm still remains as a challenge. The incorporation of plasmonic structures with photovoltaic devices has been shown to increase solar cell photo-current and may lead to new opportunities for inexpensive, and high effi ciency solar cell designs. [ 13–20 ] Recently, metallic nanostructures have been introduced into thin inorganic semiconductor solar cells (e.g. Si and GaAs solar cells) for highly effi cient light harvesting by strong light scattering behavior and concentrated near fi eld through the localized and surface plasmonic effects of different metallic nanostructures. [ 12–17 ] More recently, metallic nanostructures have been used to enhance the performance of bulk heterojunction polymer solar cells, such as introducing the localized plasmonic nanostructure of metallic nanoparticles (NPs) in carrier transport layer, [ 18–22 ] incorporate into active layer of bulk junctions, [ 23–25 ] both carrier transport layer and active layer [ 26 ] and most of them are concentrated on wide band-gap polymer, such as poly-3(hexylthiophene) (P3HT). Importantly, low bandgap polymer can cover a broad absorption range, it is therefore attractive if we can enhance the PCE of low bandgap polymer solar cell by plasmonic structure. In this study, the low bandgap polymer benzodithiophene polymers (PTB7) [ 6 ] is used to demonstrate the surface plasmonic effects of large-area metallic
TL;DR: A multiple supramolecular assembly, in which a folic acid-modified β-cyclodextrin acted as a target unit, an adamantanyl porphyrin acting as a linker unit, and graphene oxide act as a carrier unit, exhibited better drug activity and much lower toxicity than free doxorubicin in vivo.
Abstract: A multiple supramolecular assembly, in which a folic acid-modified β-cyclodextrin (1) acted as a target unit, an adamantanyl porphyrin (2) acted as a linker unit, and graphene oxide acted as a carrier unit, was successfully fabricated through non-covalent interactions and comprehensively investigated by means of UV/Vis, fluorescence, and X-ray photoelectron spectroscopies, and electron microscopy. Significantly, the graphene oxide unit could associate with the anticancer drug doxorubicin through π-π interactions, and the folic acid-modified β-cyclodextrin unit could recognize the folic acid receptors in cancer cells. Owing to the cooperative contribution of these three units, the resulting multiple supramolecular assembly, after association with doxorubicin, exhibited better drug activity and much lower toxicity than free doxorubicin in vivo.
TL;DR: Kim et al. as discussed by the authors reviewed how nanocomposite materials that combine organic and inorganic materials are attractive for use in memory components and showed that hybrid organic-inorganic devices, such as a polymer matrix in which metal nanoparticles have been incorporated, are easy to make, cost-effective, mechanically flexible and efficient.
Abstract: Tae Whan Kim and co-workers review how nanocomposite materials that combine organic and inorganic materials are attractive for use in memory components. A wide variety of structures have been used to store information by switching between two states, making for either volatile or nonvolatile memory systems; well-known examples of both types are random access memory (RAM) and computer hard disks, respectively. Among those, hybrid organic-inorganic devices–such as a polymer matrix in which metal nanoparticles have been incorporated–are easy to make, cost-effective, mechanically flexible, and efficient. Further studies will endeavour to better understand the memories' mechanisms and improve their switching speed and reproducibility. These hybrid structures are particularly promising for the development of flexible memories required to construct the next generation of portable devices.
TL;DR: In this article, the authors demonstrate the efficacy of low temperature solution-processed flexible metal nanowire networks embedded in a conductive metal oxide nanoparticle matrix as transparent conductors, and investigate their microstructural, optoelectronic, and mechanical properties in attempting to resolve nearly all of the technological issues imposed on silver nanowires networks.
Abstract: Although silver nanowire meshes have already demonstrated sheet resistance and optical transmittance comparable to those of sputter-deposited indium tin oxide thin films, other critical issues including surface morphology, mechanical adhesion and flexibility have to be addressed before widely employing silver nanowire networks as transparent conductors in optoelectronic devices. Here, we demonstrate the efficacy of low temperature solution-processed flexible metal nanowire networks embedded in a conductive metal oxide nanoparticle matrix as transparent conductors, and investigate their microstructural, optoelectronic, and mechanical properties in attempting to resolve nearly all of the technological issues imposed on silver nanowire networks. Surrounding silver nanowires by conductive indium tin oxide nanoparticles offers low wire to wire junction resistance, smooth surface morphology, and excellent mechanical adhesion and flexibility while maintaining the high transmittance and the low sheet resistance. In addition, we discuss the relationship between sheet resistance and transmittance in the silver nanowire composite transparent conductors and their maximum achievable transmittance. Although we have selected silver nanowires and indium tin oxide nanoparticle matrix as demonstration materials, we anticipate that various metal nanowire meshes embedded in various conductive metal oxide nanoparticle matrices can effectively serve as transparent conductors for a wide variety of optoelectronic devices owing to their superior performance, simple, cost-effective, and gentle processing.
TL;DR: While BSA-dispersed tubes were a potent inducer of pulmonary fibrosis, PF108 coating protected the tubes from damaging the lysosomal membrane and initiating a sequence of cooperative cellular events that play a role in the pathogenesis of pulmonary Fibrosis.
Abstract: We compared the use of bovine serum albumin (BSA) and pluronic F108 (PF108) as dispersants for multiwalled carbon nanotubes (MWCNTs) in terms of tube stability as well as profibrogenic effects in vitro and in vivo. While BSA-dispersed tubes were a potent inducer of pulmonary fibrosis, PF108 coating protected the tubes from damaging the lysosomal membrane and initiating a sequence of cooperative cellular events that play a role in the pathogenesis of pulmonary fibrosis. Our results suggest that PF108 coating could serve as a safer design approach for MWCNTs.
TL;DR: High power conversion efficiencies of over 6.0% are achieved with a squaraine compound from co-deposited photovoltaic cells with a simple device structure, in which the efficiency is insensitive to blending ratios and thicknesses of photoactive layers.
Abstract: High power conversion efficiencies of over 6.0% are achieved with a squaraine compound from co-deposited photovoltaic cells with a simple device structure, in which the efficiency is insensitive to blending ratios and thicknesses of photoactive layers. It demonstrates the huge potential of low molecular weight materials in photovoltaic cells via vacuum processes.
TL;DR: A silver nanowire-indium Tin oxide nanoparticle composite and its successful application to fully solution processed CuInSe(2) solar cells as a window layer are demonstrated, effectively replacing the traditionally sputtered both intrinsic zinc oxide and indium tin oxide layers.
Abstract: A silver nanowire-indium tin oxide nanoparticle composite and its successful application to fully solution processed CuInSe(2) solar cells as a window layer are demonstrated, effectively replacing the traditionally sputtered both intrinsic zinc oxide and indium tin oxide layers. The devices utilizing the nanocomposite window layer demonstrate photovoltaic parameters equal to or even beyond those with sputtered intrinsic zinc oxide and indium tin oxide contacts.
TL;DR: A large number of genetic variants influencing lipid levels and risk of coronary artery disease (CAD) have been identified by recent genome‐wide association studies (GWAS) and further studies are needed to confirm these findings.
TL;DR: An analytical model is proposed to predict both uplink and downlink connectivity probabilities and reveals the trade-off between these two key performance metrics and the important system parameters, such as BS and vehicle densities, radio coverage (or transmission power), and maximum number of hops.
Abstract: Infrastructure-based vehicular networks (consisting of a group of Base Stations (BSs) along the road) will be widely deployed to support Wireless Access in Vehicular Environment (WAVE) and a series of safety and non-safety related applications and services for vehicles on the road. As an important measure of user satisfaction level, uplink connectivity probability is defined as the probability that messages from vehicles can be received by the infrastructure (i.e., BSs) through multi-hop paths. While on the system side, downlink connectivity probability is defined as the probability that messages can be broadcasted from BSs to all vehicles through multi-hop paths, which indicates service coverage performance of a vehicular network. This paper proposes an analytical model to predict both uplink and downlink connectivity probabilities. Our analytical results, validated by simulations and experiments, reveal the trade-off between these two key performance metrics and the important system parameters, such as BS and vehicle densities, radio coverage (or transmission power), and maximum number of hops. This insightful knowledge enables vehicular network engineers and operators to effectively achieve high user satisfaction and good service coverage, with necessary deployment of BSs along the road according to traffic density, user requirements and service types.
TL;DR: Tau hyperphosphorylation induced by synaptic activity was strongly associated with inactivation of protein phosphatase 2A (PP2A), and this inactivation can be reversed by pretreatment of zinc chelator, and these results suggest that synaptically released zinc promotes tau hyper phosphorylation through PP2A inhibition.
TL;DR: This study is the first one to determine genome-wide lncRNAs expression patterns in RCCC by microarray, which revealed that lnc RNAs differentially expressed in tumor tissues and normal tissues may exert a partial or key role in tumor development.
Abstract: Background
Long noncoding RNAs (lncRNAs) are an important class of pervasive genes involved in a variety of biological functions. They are aberrantly expressed in many types of cancers. In this study, we described lncRNAs profiles in 6 pairs of human renal clear cell carcinoma (RCCC) and the corresponding adjacent nontumorous tissues (NT) by microarray.
TL;DR: In this paper, a simple method is demonstrated to improve the film-forming properties and air stability of a conjugated polyelectrolyte (CPE) without complicated synthesis of new chemical structures.
Abstract: A simple method is demonstrated to improve the film-forming properties and air stability of a conjugated polyelectrolyte (CPE) without complicated synthesis of new chemical structures. An anionic surfactant, sodium dodecybenzenesulfonate (SDS), is mixed with cationic CPEs. The electrostatic attraction between these two oppositely-charged materials provides the driving force to form a stable CPE-surfactant complex. Compared with a pure CPE, this electrostatic complex is not only compatible with highly hydrophobic bulk-heterojunction (BHJ) films, e.g. poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PCBM), but also works well with other low bandgap polymer-based BHJ films. Using this complex as a cathode interface layer, a high power conversion efficiency of 4% can be obtained in P3HT:PCBM solar cells together with improved stability in air. Moreover, ∼20% performance enhancement can also be achieved when the complex is used as an interlayer to replace calcium metal for low bandgap polymer-based BHJ systems.
TL;DR: It is demonstrated that HFD may induce oxidative stress, mitochondrial damage and apoptosis in the inner ear, and it provided evidence regarding the link between HFD and an increased risk of age-related hearing loss.
TL;DR: A wavelength-saving topology of a quantum key distribution (QKD) network based on passive optical elements is proposed, and the field test of this network on commercial telecom optical fiber at the frequency of 20 MHz is reported.
Abstract: We propose a wavelength-saving topology of quantum key distribution(QKD) network based on passive optical elements, and report the field test of this network on the commercial telecom optical fiber. In this network, 5 nodes are supported with 2 wavelengths, and every two nodes can share secure keys directly at the same time. All QKD links in the network operate at the frequency of 20 MHz. We also characterized the insertion loss and crosstalk effects on the point-to-point QKD system after introducing this QKD network.
TL;DR: In this paper, Co3O4 is used for the first time to achieve novel nanoenergetic materials (nEMs) by integrating nano-Al with Co 3O4 nanorods that are synthesized by a chemical method.
TL;DR: In this paper, the authors investigate the flexural behavior of six concrete beams with various reinforcements, including ordinary steel bars, steel-fiber reinforced polymer composite composite bars, pure fiber-reinforced polymer bars (either carbon fiber reinforced polymer bars or basalt fiber reinforced polymers), and hybrid bars (steel bars and basalt fibre reinforced polymer composites).
Abstract: Experimental studies investigating the flexural behavior of six concrete beams were conducted with various reinforcements, including ordinary steel bars, steel-fiber reinforced polymer composite bars, pure fiber-reinforced polymer bars (either carbon fiber reinforced polymer bars or basalt fiber reinforced polymer bars), and hybrid bars (steel bars and basalt fiber reinforced polymer bars). The test results show the following: (a) steel-fiber reinforced polymer composite bar beams exhibit stable post-yield stiffness after the yielding of the inner steel bar of the steel-fiber reinforced polymer composite bar and concrete crushed after the rupture of the outer fiber-reinforced polymer of the steel-fiber reinforced polymer composite bar; (b) the ordinary reinforced concrete beam has the largest ductility coefficient, but the ultimate load was just approximately 31% of that of the corresponding steel-fiber reinforced polymer composite bar beams; (c) brittle shear failure was observed for both fiber reinforce...
TL;DR: In this article, the authors provide an overview of the current status of hydrazine-based CIGS solar-cell fabrication, including the three major steps of this deposition process: dissolution of the precursor materials, deposition of a film from the resulting precursor solution, and the completion and characterization of a photovoltaic device following absorber deposition.
Abstract: The hydrazine-based deposition of Cu(In,Ga)(S,Se)2 (CIGS) thin films has attracted considerable attention in recent years due to its potential for the high-throughput production of photovoltaic devices based on this absorber material. This article provides an introduction as well as presenting a complete picture of the current status of hydrazine-based CIGS solar-cell fabrication, including the three major steps of this deposition process: dissolution of the precursor materials in hydrazine, deposition of a film from the resulting precursor solution, and the completion and characterization of a photovoltaic device following absorber deposition. Recent discoveries are then discussed, regarding the dissolution chemistry of the relevant precursor complexes in hydrazine, which together represent the true foundation of this processing method. Recent studies on CIGS film formation are then summarized, including the control and analysis of the crystalline phase, electronic bandgap, and film morphology. Finally, the latest progress in high-performance device fabrication is highlighted, with a focus on optoelectronic characterization including current–voltage, junction capacitance, and minority carrier lifetime measurements. Finally, a discussion and future outlook is provided.
TL;DR: In this article, the effects of upconversion nanophosphors (UCNPs) on plant development were investigated using mung beans as a model. But the effect of UCNPs on plants and on animals after subsequent oral ingestion of the plants has not been studied previously.
Abstract: Upconversion nanophosphors (UCNPs) have been widely used in bioscience and bioimaging, but the effect of UCNPs on plants and on animals after subsequent oral ingestion of the plants has not been studied previously. Herein, we investigate the effects of UCNPs on plant development using mung beans as a model. Incubation at a high UCNP concentration of 100 μg/mL led to growth inhibition, while a low concentration of 10 μg/mL promoted their development. Confocal imaging showed that UCNPs accumulated in the seeds and were transferred from seeds and roots to stems and leaves through the vascular system. Quantitative study by radioanalysis showed the distribution of UCNPs in the plant on the 5th day after incubation decreased in the order (root > seed > leaf > stem). After UCNP-treated bean sprouts were orally ingested by mice, UCNPs were completely excreted with feces, without absorption of residual amounts. Histology and hematology results showed no detectable toxic effects of UCNP-treated mung beans on exposed mice.
TL;DR: This article proposes that the mobile terminals in MCN act as both sensor nodes and gateways for WSN in the converged networks, and simulation results show that better system performance can be achieved in WSN by using interactive optimization with MCN.
Abstract: In recent years, machine-to-machine (M2M) communications, which do not need direct interactions from human beings, are booming to meet the fast-increasing requirements of datacentric wireless services and applications. Mobile cellular networks (MCN) and wireless sensor networks (WSN) are evolving from heterogeneous networks to converged networks, in order to support M2M communications. In this article, we investigate and discuss key technical challenges and opportunities for the convergence of MCN and WSN. We propose that the mobile terminals in MCN act as both sensor nodes and gateways for WSN in the converged networks. We evaluated the performance gain, and our simulation results show that better system performance, in terms of throughput, delay, and network lifetime, can be achieved in WSN by using interactive optimization with MCN.