Effects of structure and electronic properties of D-π-A organic dyes on photovoltaic performance of dye-sensitized solar cells

Herein,we examine the performance of dye-sensitized solar cells containing five D-π-A organic dyes designed by systematic modification of π-bridge size and geometric structure.Each dye has a simple push-pull structure with a triarylamino group as an electron donor,bithiophene-4,4-dimethyl-4 H-cyclopenta 1,2-b:5,4-b’]dithiophene(M11),4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophenethiophene(M12),thiophene-4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene(M13),4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene-benzene(M14),and 4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene(M15)units asπ-bridges,and cyanoacrylic acid as an electron acceptor/anchor.The extension of theπ-bridge linkage favors wide-range absorption but,because of the concomitant molecular volume increase,hinders the efficient adsorption of dyes on the TiO_(2) film surface.Hence,higher loadings are achieved for smaller dye molecules,resulting in(i)a shift of the TiO_(2) conduction band edge to more negative values,(ii)a greater photocurrent,and(iii)suppressed charge recombination between the photoanode and the redox couple in the electrolyte.Consequently,under one-sun equivalent illumination(AM 1.5 G,100 mW/cm^(2)),the highest photovoltage,photocurrent,and conversion efficiency(η=7.19%)are observed for M15,which has the smallest molecular volume among M series dyes.

Growth of Indium Nanorods by Magnetron Sputtering

Indium nanorods are grown on silicon substrates by using magnetron-sputtering technique. Film morphologies and nanorod microstructure are investigated by using scanning electron microscopy, high-resolution transmission electron microscopy （HRTEM）, and x-ray diffraction. It is found that the mean diameter of the nanorods ranges from 30nm to 100nm and the height ranges from 30nm to 200nm. The HRTEM investigations show that the indium nanorods are single crystals and grow along the [100] axis. The nanorods grow from the facets near the surface undulation that is caused by compressive stress in the indium grains generated during grain coalescence process. For low melting point and high diffusivity metal, such as bismuth and indium, this spontaneous nanorod growth mechanism can be used to fabricate nanostructures.

Magnetic properties of samarium and gadolinium co-doping Mn-Zn ferrites obtained by sol-gel auto-combustion method

Mn-Zn ferrites doped with different contents of Sm^（3＋） and Gd^（3＋） ions were prepared by sol-gel auto-combustion method and characterized by Fourier transform infrared spectroscopy（FTIR）, thermogravimetric analysis（TG）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and vibrating sample magnetometer（VSM）. When samples were calcined in a relatively low temperature below 1100 °C, secondary phases（α-Fe_2O_3） could be identified. Therefore, in order to acquire pure and better crystallinity, the suitable calcining temperature of powders was selected at 1200 °C. It was also found that all the samples consisting of ferrite phases of typical spinel cubic structure and average crystallite sizes between 31.5 and 38.2 nm were obtained after calcining at 1200 oC for 4 h. The lattice parameters increased almost linearly with increasing Sm content. A dense microstructure was obtained after sintering at 1250 °C for 4 h. Through the analysis of magnetic properties, hysteresis loops for all the samples were narrow with low values of coercivity and retentivity, indicating the paramagnetic nature of these samples. And saturation magnetization Ms strongly depended on the type of additive to reach a maximum of 47.99 emu/g for x=0.015, which showed a great promise for hyperthermia applications.

Oxygen Functionalization-Induced Charging Effect on Boron Active Sites for High-Yield Electrocatalytic NH_(3) Production

Ammonia has been recognized as the future renewable energy fuel because of its wide-ranging applications in H_(2) storage and transportation sector.In order to avoid the environmentally hazardous Haber-Bosch process,recently,the third-generation ambient ammonia synthesis has drawn phenom-enal attention and thus tremendous efforts are devoted to developing efficient electrocatalysts that would circumvent the bottlenecks of the electrochemical nitrogen reduction reaction(NRR)like competitive hydrogen evolution reac-tion,poor selectivity of N_(2) on catalyst surface.Herein,we report the synthesis of an oxygen-functionalized boron carbonitride matrix via a two-step pyrolysis technique.The conductive BNCO(1000)architecture,the compatibility of B-2p_(z) orbital with the N-2p_(z) orbital and the charging effect over B due to the C and O edge-atoms in a pentagon altogether facilitate N_(2) adsorption on the B edge-active sites.The optimum electrolyte acidity with 0.1 M HCl and the lowered anion crowding effect aid the protonation steps of NRR via an associative alternating pathway,which gives a sufficiently high yield of ammonia(211.5μg h^(−1) mg_(cat)^(−1))on the optimized BNCO(1000)catalyst with a Faradaic efficiency of 34.7%at−0.1 V vs RHE.This work thus offers a cost-effective electrode material and provides a contemporary idea about reinforcing the charging effect over the secured active sites for NRR by selectively choosing the electrolyte anions and functionalizing the active edges of the BNCO(1000)catalyst.

Enhancement of MoTe2 near-infrared absorption with gold hollow nanorods for photodetection

Infrared(IR)light photodetection based on two dimensional(2D)materials of proper bandgap has attracted increasing attention.However,the weak IR absorption in 2D materials,due to their ultrathin attribute and indirect bandgap in multilayer structures,degrades their performance when used as IR photodetectors.In this work,we utilize the fact that few-layer MoTe2 flake has a near-IR(NIR)bandgap and demonstrate a^60-fold enhancement of NIR response by introducing a gold hollow nanorods on the surface.Such gold hollow nanorods have distinct absorption peak located also at the NIR regime,therefore induces strong resonance,benefitting NIR absorption in MoTe2,resulting in strong near-field enhancement.With the evidence from steady and transient state optical spectra,we confirm that the enhancement of NIR response originates only photon absorption,rather than electron transport at interfaces as observed in other heterostructures,therefore,precluding the requirement of high-quality interfaces for commercial applications.

Detection of latent fingerprints using luminescent Gd_(0.95)Eu_(0.05)PO_(4) nanorods

Lanthanide ions doped luminescent materials are widely studied for latent fingerprint detection.However,most of these materials are synthesized at very high temperatures and use UV C light for visualization,which is harmful to eye,skin,etc.Herein,the Gd_(0.95)Eu_(0.05)PO_(4) nanorods synthesized by a simple co-precipitation method at 185℃ were reported for latent fingerprint visualization under 395 nm light.The Gd_(0.95)Eu_(0.05)PO_(4) nanomaterial has monoclinic crystal structure and shows rod-shaped morphology.Further,these Gd_(0.95)Eu_(0.05)PO_(4) nanorods exhibit excellent photoluminescence properties and strong fuchsia emission under UV light.These nanorods have been employed for developing latent fingerprints on various porous and non-porous substrates by the powder dusting technique,which exhibits clear and well defined details with high contrast,selectivity and sensitivity under 395 nm UV light.Latent fingerprints developed after 72 h of their deposition also show clear contrast with these nanorods.Therefore,the Gd_(0.95)Eu_(0.05)PO_(4) nanorods can be used for latent fingerprint visualization applications.

3D-printing-assisted flexible pressure sensor with a concentric circle pattern and high sensitivity for health monitoring

In this study,a flexible pressure sensor is fabricated using polydimethylsiloxane(PDMS)with a concentric circle pattern(CCP)obtained through a fused deposition modeling(FDM)-type three-dimensional(3D)printer and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)as the active layer.Through layer-by-layer additive manufacturing,the CCP surface is generated from a thin cone model with a rough surface by the FDM-type 3D printer.A novel compression method is employed to convert the cone shape into a planar microstructure above the glass transition temperature of a polylactic acid(PLA)flament.To endow the CCP surface with conductivity,PDMS is used to replicate the compressed PLA,and PEDOT:PSS is coated by drop-casting.The size of the CCP is controlled by changing the printing layer height(PLH),which is one of the 3D printing parameters.The sensitivity increases as the PLH increases,and the pressure sensor with a 0.16 mm PLH exhibits outstanding sensitivity(160 kPa^(-1)),corresponding to a linear pressure range of 0-0.577 kPa with a good linearity of R^(2)=0.978,compared to other PLHs.This pressure sensor exhibits stable and repeatable operation under various pressures and durability under 6.56 kPa for 4000 cycles.Finally,monitoring of various health signals such as those for the wrist pulse,swallowing,and pronunciation of words is demonstrated as an application.These results support the simple fabrication of a highly sensitive,flexible pressure sensor for human health monitoring.

Biomineralized and chemically synthesized magnetic nanoparticles:A contrast

Magnetic nanoparticles(MNPS)have widely been synthesized through chemical processes for biomedical applications over the past few decades.Recently,a new class of MNPs,known as bacterial magnetosomes,has been isolated from magnetotactic bacteria,a natural source.These magnetosomes are magnetite or greigite nanocrystals which are biomineralized in the bacterial cell and provide magnet-like properties to it.Contrary to MNPs,bacterial magnetosomes are biocompatible,lower in toxicity,and can be easily cleared from the body due to the presence of a phospholipid bilayer around them.They also do not demonstrate aggregation,which makes them highly advantageous.In this review,we have provided an in-depth comparative account of bacterial magnetosomes and chemically synthesized MNPs in terms of their synthesis,properties,and biomedical applications.In addition,we have also provided a contrast on how magnetosomes might have the potential to successfully substitute synthetic MNPs in therapeutic and imaging applications.

Spontaneous Hillock Growth on Indium Film Surface

Uniformly distributed indium hillocks are grown on silicon substrates by dc magnetron sputtering. The morphologies and the microstructures have been investigated by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and x-ray diffraction （XRD）. From the TEM and SEM images, we find that, at the earlier stage, the grain coalescent process dominates. This coalescent process induces a larger compressive stress. We believe that the drive force for hillock growth comes from this compressive stress. Under this compressive stress, the grain locating in the middle of several grains are extruded from these grains, and then a hillock forms with the increasing deposition time. For low melting point and high diffusion coefficient metal, such as bismuth and indium, this spontaneous-hillock growth mechanism can be used to fabricate well aligned nanostructures.

Erratum to: Biomineralized and chemically synthesized magnetic nanoparticles: A contrast

Erratum to:Front.Mater.Sci.2020,14(4):387^401 DOI:10.1007/s 11706-020-0531-7 Page 391,the caption of Fig.3 uBiomineralization and role of magnetosome membrane proteins in synthesis of BM crystals in MTB(Magnetosome proteins:MamR,MamS,MamT,MamP,MamD,MamF,MamG,MamE(protease dependent),MamC,MamM,MamN,MamO,MamK,MamJ,MamE,Maml,MamL,MamQ,MamB)."

Large-diameter indium antimonide microwire based broadband and robust optical switch

Various nanophotonic devices based on semiconductor wires with a diameter of several ten nanometers have been studied.Nevertheless,studying the optoelectronics properties and performance of such devices based on large-diameter wires is interesting and meaningful.Here,we successfully grew the micronsized indium antimonide(InSb) wires,and examined their nonlinear optical properties by Z-scan and I-scan(power-dependent) methods within the wavelength range of 0.8-2.8 μm.Furthermore,we demonstrated InSb micro wires(MWs) working as an effective and robust optical switch within 1-2.8 μm wavelength.The findings can open possibilities for research on more large-diameter MWs made from other semiconductor materials for photonic and electronic devices.

Unconventional ferroelectricity in half-filling states of antiparallel stacking of twisted WSe_(2)

We report on emergence of an abnormal electronic polarization in twisted double bilayer WSe_(2) in antiparallel interface stacking geometry,where local centrosymmetry of atomic registries at the twist interface does not favor the spontaneous electronic polarizations as recently observed in the parallel interface stacking geometry.The unconventional ferroelectric behaviors probed by electronic transport measurement occur at half filling insulating states at 1.5 K and gradually disappear at about 40 K.Single band Hubbard model based on the triangular moirélattice and the interlayer charge transfer controlled by insulating phase transition are proposed to interpret the formation of electronic polarization states near half filling in twisted WSe_(2) devices.Our work highlights the prominent role of many-body electronic interaction in fostering novel quantum states in moiré-structured systems.

Room temperature Ⅲ–Ⅴ nanolasers with distributed Bragg reflectors epitaxially grown on(001) silicon-on-insulators

Efficient, scalable, bufferless, and compact Ⅲ–V lasers directly grown on(001)-oriented silicon-on-insulators(SOIs) are preferred light sources in Si-photonics. In this article, we present the design and operation of Ⅲ–V telecom nanolaser arrays with integrated distributed Bragg reflectors(DBRs) epitaxially grown on industry-standard(001) SOI wafers. We simulated the mirror reflectance of different guided modes under various mirror architectures, and accordingly devised nanoscale DBR gratings to support high reflectivity around1500 nm for the doughnut-shaped TE01 mode. Building from InP/InGaAs nanoridges grown on SOI, we fabricated subwavelength DBR mirrors at both ends of the nanoridge laser cavities and thus demonstrated room-temperature low-threshold InP/InGaAs nanolasers with a 0.28 μm^2 cross-section and a 20 μm effective cavity length. The direct growth of these bufferless nanoscale Ⅲ–V light emitters on Si-photonics standard(001) SOI wafers opens future options of fully integrated Si-based nanophotonic integrated circuits in the telecom wavelength regime.

UV-assisted flash light welding process to fabricate silver nanowire/graphene on a PET substrate for transparent electrodes

Graphene oxide and silver nanowires were bar coated onto polyethylene terephthalate （PET） substrates and then welded using an ultraviolet （UV）-assisted flash light irradiation process to achieve both high electrical conductivity and low haze. The irradiation process connected adjacent silver nanowires by welding, while simultaneously reducing the graphene oxide to graphene. This process was performed using a custom W-assisted flash light welding system at room temperature under ambient conditions and was extremely rapid, with processing time of several milliseconds. The effects of varying the weight fractions of the silver nanowires and graphene oxide and of varying the W-assisted flash light welding conditions （light energy and pulse duration） were investigated. The surface morphologies of the welded silver nanowire/graphene films were analyzed using scanning electron microscopy. Optical characterizations, including transmittance and haze measurements, were also conducted using a spectrophotometer. To test their resistance to oxidation, the welded silver nanowire/graphene films were subjected to high temperature in a furnace （100 ℃）, and their sheet resistances were measured every hour. The flash light welding process was found to yield silver nanowire/graphene films with high oxidation resistance, high conductivity （14.35 Ω·sq-1）, high transmittance （93.46%）, and low haze （0.9%）. This material showed uniform temperature distribution when applied as a resistive heating film.

Structural effects of 3D printing resolution on the gauge factor of microcrack-based strain gauges for health care monitoring

Measurements of physiological parameters such as pulse rate,voice,and motion for precise health care monitoring requires highly sensitive sensors.Flexible strain gauges are useful sensors that can be used in human health care devices.In this study,we propose a crack-based strain gauge fabricated by fused deposition modeling(FDM)-based three-dimensional(3D)-printing.The strain gauge combined a 3D-printed thermoplastic polyurethane layer and a platinum layer as the flexible substrate and conductive layer,respectively.Through a layer-by-layer deposition process,self-aligned crack arrays were easily formed along the groove patterns resulting from stress concentration during stretching motions.Strain gauges with a 200-μm printing thickness exhibited the most sensitive performance(~442%increase in gauge factor compared with that of a flat sensor)and the fastest recovery time(~99%decrease in recovery time compared with that of a flat sensor).In addition,500 cycling tests were conducted to demonstrate the reliability of the sensor.Finally,various applications of the strain gauge as wearable devices used to monitor human health and motion were demonstrated.These results support the facile fabrication of sensitive strain gauges for the development of smart devices by additive manufacturing.

Milk protein-shelled gold nanoparticles with gastrointestinally active absorption for aurotherapy to brain tumor

Orally absorbable gold nanoparticles(AuNP)having cancer ablation therapy is strongly demanded to treat glioblastoma multiforme(GBM)for patients with its highest incidence rate.Here,we develop a milk protein lactoferrin-conjugated AuNP for its oral absorption and targeting to the GBM through the interaction between lactoferrin(Lf)and lactoferrin receptor(LfR)that is highly expressed in the intestine,blood-brain barrier and GBM.For stability and long circulation of AuNP,glutathione and polyethylene glycol(PEG)is introduced,which is called to Lf-PEG-AuNP.When Lf-PEG-AuNP are orally administered to orthotopic GBM-bearing mice,11-fold and 8-fold higher concentrations of AuNP are measured in bloodstreams and GBM in the brain,respectively,compared with unconjugated-AuNP.Therefore,orally administered Lf-PEG-AuNP exhibit an outstanding temperature rise in GBM by irradiating laser and significantly reduce tumor volume.Collectively,we suggest that the Lf-PEG-AuNP can fundamentally target GBM in the brain through oral absorption,and that its efficient photothermal therapy is possible.

Ultra-broadband reflectionless Brewster absorber protected by reciprocity

The Brewster’s law predicts zero reflection of p-polarization on a dielectric surface at a particular angle.However,when loss is introduced into the permittivity of the dielectric,the Brewster condition breaks down and reflection unavoidably appears.In this work,we found an exception to this long-standing dilemma by creating a class of nonmagnetic anisotropic metamaterials,where anomalous Brewster effects with independently tunable absorption and refraction emerge.This loss-independent Brewster effect is bestowed by the extra degrees of freedoms introduced by anisotropy and strictly protected by the reciprocity principle.The bandwidth can cover an extremely wide spectrum from dc to optical frequencies.Two examples of reflectionless Brewster absorbers with different Brewster angles are both demonstrated to achieve large absorbance in a wide spectrum via microwave experiments.Our work extends the scope of Brewster effect to the horizon of nonmagnetic absorptive materials,which promises an unprecedented wide bandwidth for reflectionless absorption with high efficiency.

Dual response of graphene-based ultra-small molecular junctions to defect engineering

It has been reported that N and B doping induce a quasi-bound state that suppresses the conduction in graphene nanoribbon （GNR）-based junctions, while an H defect or a pyridine-like N-atom （PN） substitution at the edge of the GNR does not affect the transmission close to the Fermi energy. However, these results may vary when the size of the functional unit of the GNR junction decreases to a molecular level. In this study, a defect is introduced to a test-bed architecture consisting of a polyacene bridging two zigzag GNR electrodes, which changes the molecular state alignment and coupling to the electrode states, and varies the equivalence between two eigen-channels at the Fermi level. It is revealed that B and N atom substitution, and H defects play a dual role in the molecular conductance, whereas the PN substitution acts as an ineffective dopant. The results obtained from density functional theory combined with the non-equilibrium Green＇s function method aid in determining the optimal design for the GNR-based ultra-small molecular devices via defect engineering.

Electron-electron interactions in monolayer graphene quantum capacitors

我们表明电子电子(e-e ) 的效果在单层 graphene 量电容器的相互作用。Ultrathin 钇氧化物在最高门的设备几何学作为绝缘的层显示出优秀性能。结构和钇氧化物层的绝缘的常数小心地被学习了。从量电容检索的反的压缩的可能性在不同温度在单层 graphene 为 e-e 相互作用与理论预言相当同意了很好。我们发现电子洞水坑在 graphene 在低密度的搬运人区域起了一个重要作用。由认为温度依赖者费用是变化，我们建立了一个模型解释在迪拉克点附近在单层 graphene 从 e-e 相互作用发源的舍入效果。

Polydopamine directed MnO@C microstructures as electrode for lithium ion battery

In this work,a facile process was reported to fabricate amorphous carbon-coated MnO micropeanuts(MPs)with 1.8μm in length and 1.0μm in width using hydrothermal reaction followed by heat treatment in the oxygen-free environment.With Mn Cl_2 and KMnO_4 dissolved in the mixture of ethylene glycol and water,MnCO_3 MP precursors were obtained via the hydrothermal reaction with dopamine as surfactant.Then MnCO_3 MP was annealed at 600°C in the N_2 atmosphere and was transformed into MnO MP,and simultaneously the formed polydopamine during the hydrothermal reaction was carbonized to produce amorphous carbon-coating on the MnO MP surface.In contrast,MnCO_3 nanoparticle(NP)precursor was formed without the addition of dopamine and MnO NP agglomerates were prepared after pyrolysis.The carbonization of polydopamine during thermolysis improves the electrical conductivity and thermal stability of the MnO MP and thus its electrochemical performance as electrode materials for lithium ion battery.Hopefully,this facile strategy for fabricating and designing carbon-coated materials would inspire more novel nanostructures and applications thereof.