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Solid-state fiber dye-sensitized solar cells (SS-FDSSCs) have been the subject of intensive attention and development in recent years. Although this field is only in its infancy, metal-organic frameworks (MOFs) are one such material that has been utilized to further improve the power conversion efficiency of solar cells. In this study, MOF-integrated DSSCs were shown to have potential in the development of solar cell devices with efficiency comparable to or better than that of conventional solar cells. The power conversion efficiency (PCE) of SS-FDSSCs was improved by embedding MOF-801 into a mesoporous-TiO2 (mp-TiO2) layer, which was used as a photoanode in SS-FDSSCs, which are inherently flexible. The PCE of the MOF-integrated SS-FDSSCs was 6.50%, which is comparable to that of the reference devices (4.19%). The MOF-801 enhanced SS-FDSSCs decreased the series resistance (Rs) value, resulting in effective electron extraction with improved short-circuit current density (JSC), while also increasing the shunt resistance (Rsh) value to prevent the recombination of photo-induced electrons. The result is an improved fill factor and, consequently, a higher value for the PCE.

Magnetic resonance angiography (MRA) is an important imaging technique that can be used to identify and characterize various types of vascular diseases. However, currently used molecular contrast agents are unsuitable for MRA due to the short intravascular retention time, the whole-body distribution, and the relatively low contrast effect. In this study, we developed a vascular analysis contrast agent (i.e., VasCA) for MRA, which is a simple and biocompatible 1:1 host-guest assembly of PEGylated β-cyclodextrin and gadolinium chelate with renal clearable size and high relaxivity (r1 = 9.27 mM-1 s-1). Its biocompatibility was confirmed by in vivo animal studies as well as in vitro 3D cell culture. In a tumor-bearing rat model, VasCA circulated in the blood vessels much longer (4.3-fold increase) than gadoterate meglumine (Dotarem) and was mainly excreted by the renal system after intravenous injection. This feature of VasCA allows characterization of tumor microvasculature (e.g., feeding and draining vessels) as well as visualization of small vessels in the brain and body organs. Furthermore, after treatment with an angiogenesis inhibitor (i.e., sorafenib), VasCA revealed the vessel normalization process and allowed the assessment of viable and necrotic tumor regions. Our study provides a useful tool for diverse MRA applications, including tumor characterization, early-stage evaluation of drug efficacy, and treatment planning, as well as diagnosis of cardiovascular diseases.

Fiber-shaped dye-sensitized solar cells (FDSSCs) represent promising futuristic flexible or wearable power sources, owing to their simple fabrication process, light weight, weavability, and wearability. Along with strategies on changing the properties of semiconductor materials, the effects of incorporating silver-embedded SiO2 nanoparticles (Ag@SiO2 NPs) on the photoanodes of solid-state FDSSCs (SS-FDSSCs) are investigated. The power conversion efficiency (PCE) of SS-FDSSCs with Ag@SiO2 NPs reaches 5.38%, which is comparable to the reference (3.98%). The PCEs remain at 95% between −16.9 to 91.7 °C, indicating the operational stability of SS-FDSSCs within this temperature range. The fabricated SS-FDSSCs, whose radii were 2 mm, maintains more than 90% of their efficiency over 500 bending cycles and 10 washing cycles.

In this study, we report a UV-light-curable azide ligand (AzL) for the micro-patterning of PeQDs. AzL can be attached to the surface of the PeQDs during their synthesis without additional ligand exchange. Using the AzL-grafted CsPbBr3 PeQDs, high-color-purity 240 × 240 μm2 square-shaped patterns were successfully fabricated using UV light irradiation, which corresponds to a resolution of >50 pixels per inch.

This research reports on the atomic layer deposition (ALD) mechanism of MgO thin film using bis(cyclopentadienyl) magnesium [Mg(Cp)2] as the Mg-precursor and O3 or H2O as an oxygen source. The different growth temperature effects of growth behaviour for the two types of oxygen sources were carefully evaluated. Insufficient H2O purging time caused the Mg-hydrides to remain in the deposited MgO thin film, which may cause inhibited growth on the bare-Si substrate. For the case of O3-based ALD, such an adverse reaction was not observed. However, it showed a complicated temperature-dependent growth behaviour, and an abnormal ‘overgrowth’ zone around 290 °C was found when the growth temperature was varied from 140 °C to 390 °C. The carbonate intermediates and OH− reactive sites involving the growth mechanism with Cp-ring rupture were suggested. This mechanism was supported by the subsequent chemical and physical properties analysis, correlating the electrical characteristics using the planar metal–insulator–metal capacitors [metal layer was titanium nitride (TiN)], with the substrate temperature varying from 230 °C to 390 °C. The MgO deposited at 290 °C, where oligomerisation may happen between ligands after the Cp-ring rupture, caused the void formation, low density, and a relatively high-impurity level. The post-deposition and post-metallisation annealing conditions were examined for the optimal leakage current and dielectric constant of the MgO film. MgO and TiN showed local epitaxial growth due to the close lattice match. This finding suggested the possible use of the in situ crystallised MgO as a crystallisation seed layer for ultrathin (

Dye-sensitized solar cells (DSSCs) have attracted intense scientific interest due to their low cost, environmentally friendly operation, and relatively high efficiency. In particular, solid-state f...

Perovskite nanocrystals (NCs) are promising emissive materials for application in light-emitting diodes (LEDs) due to their high quantum efficiency and narrow full width at half maximum (FWHM). However, the ion bonding character of perovskite leads to their quick chemical decomposition under atmospheric moisture. Herein, we present CsPbBr3 perovskite NCs that achieved improved efficiency and stability with the addition of water during the synthesis process. The CsPbBr3 NCs synthesized with a controlled amount of water exhibited a quantum yield greater than 90%, sustained stability over 35 days and a much narrower FWHM than CsPbBr3 NCs that did not use water. Finally, water-added perovskite NC LEDs were fabricated and they showed a nearly 5-times improvement in current efficiency compared to the reference device.

Mie backscattering-based coloration of water-dispersed polymer particles is investigated. Diluted colloids and light absorber-added colloids are individually prepared to study the scattering properties. Light absorber-added colloids show ~2.9-fold higher colour saturation than diluted colloids because of the effective elimination of Mie forward scattering. Mechanism of selective extraction of Mie backscattering-based colour in the presence of light absorbers is explained by path length difference of Mie forward and backscattering. Using stimuli-responsive polymer particles, Mie scattering colour-based sensors that respond to pH and heavy metal ions are prepared.

Semitransparent organic solar cells (ST-OSCs) are considered to be an influential tool for aesthetic and economic building-integrated photovoltaics, which can be fabricated by the printing technology. A poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and ionic liquid (IL) composite has been considered as an electrode for ST-OSCs because of its high electrical conductivity, high transparency, and printability. However, we found that the introduction of IL into the PEDOT:PSS solution for enhancing its electrical conductivity results in (1) nonreliable printing of PEDOT:PSS/IL composite films because of gradual gelation of the mixture solution and (2) the production of chemically reactive ion pairs during ion exchange between PSS and IL, which induces the oxidation of the underlying organic semiconductors during printing. To solve these problems, we developed a sequential printing method using pristine PEDOT:PSS and IL solutions to retard ion exchange, thus preventing chemical doping of organic semiconductors by newly generated ion pairs. Finally, by using only solution processes, we demonstrate efficient ST-OSCs with a printed PEDOT:PSS/IL composite as the top electrode, exhibiting a power conversion efficiency of 6.32% at an average visible transmittance of 35.4%.

Microfluidics offers promising methods for aligning cells in physiologically relevant configurations to recapitulate human organ functionality. Specifically, microstructures within microfluidic devices facilitate 3D cell culture by guiding hydrogel precursors containing cells. Conventional approaches utilize capillary forces of hydrogel precursors to guide fluid flow into desired areas of high wettability. These methods, however, require complicated fabrication processes and subtle loading protocols, thus limiting device throughput and experimental yield. Here, we present a swift and robust hydrogel patterning technique for 3D cell culture, where preloaded hydrogel solution in a microfluidic device is aspirated while only leaving a portion of the solution in desired channels. The device is designed such that differing critical capillary pressure conditions are established over the interfaces of the loaded hydrogel solution, which leads to controlled removal of the solution during aspiration. A proposed theoretical model of capillary pressure conditions provides physical insights to inform generalized design rules for device structures. We demonstrate formation of multiple, discontinuous hollow channels with a single aspiration. Then we test vasculogenic capacity of various cell types using a microfluidic device obtained by our technique to illustrate its capabilities as a viable micro-manufacturing scheme for high-throughput cellular co-culture.

Volatile organic compounds (VOCs) that evaporate under standard atmospheric conditions are of growing concern. This is because it is well established that VOCs represent major contamination risks since release of these compounds into the atmosphere can contribute to global warming, and thus, can also be detrimental to the overall health of worldwide populations including plants, animals, and humans. Consequently, the detection, discrimination, and quantification of VOCs have become highly relevant areas of research over the past few decades. One method that has been and continues to be creatively developed for analyses of VOCs is the Quartz Crystal Microbalance (QCM). In this review, we summarize and analyze applications of QCM devices for the development of sensor arrays aimed at the detection of environmentally relevant VOCs. Herein, we also summarize applications of a variety of coatings, e.g., polymers, macrocycles, and ionic liquids that have been used and reported in the literature for surface modification in order to enhance sensing and selective detection of VOCs using quartz crystal resonators (QCRs) and thus QCM. In this review, we also summarize novel electronic systems that have been developed for improved QCM measurements.

A noncontact single-beam acoustic trapping technique has proven to be a promising tool for cell manipulation and characterization that provide essential knowledge for a variety of biomedical applications. Here, we investigated cell characteristics as to whether the calcium responses of suspended breast cancer cells to different acoustic trapping forces are related to their invasiveness. For this, we combined a single-beam acoustic trapping system with a 30-MHz press-focused lithium niobate ultrasound transducer and an epifluorescence microscope. Using the system, intracellular calcium changes of suspended MDA-MB-231 (highly invasive) and MCF-7 (weakly invasive) cells were monitored while trapping the cells at different acoustic pressures. The results showed that a single suspended breast cancer cell isolated by the acoustic microbeam behaved differently on the calcium elevation in response to changes in acoustic trapping force, depending on its invasiveness. In particular, the MDA-MB-231 cells exhibited higher calcium elevation than MCF-7 cells when each cell was trapped at low acoustic pressure. Based on these results, we believe that the single-beam acoustic trapping technique has high potential as an alternative tool for determining the degree of invasiveness of suspended breast cancer cells.

Environmentally harmless Antimony sulfide (Sb2S3) photoanode introduced water splitting device have a great potential for producing hydrogen from its optical characteristic. However, fabrication of highly pure Sb2S3 film by solution process has been suppressed due to the presence of various sulfide antimony compounds while chemical synthesis process. Here, high phase purity and high crystallinity Sb2S3 nanocrystal was successfully fabricated by mechanical alloying method. The solvent free and simple fabrication process realized low manufacturing cost of Sb2S3 nanocrystal fabrication without environmental hazard. Optical characterization by XRD, XPS and Raman spectroscopy confirmed that Sb2S3 nanocrystal film has high phase purity with high crystallinity. Furthermore, observed SEM images shows that fabricated Sb2S3 nanocrystal based nanostructure has high thermal stability till 300 °C. Finally, nanostructured Sb2S3 photoanode introduced water splitting device presented a saturation photocurrent of 0.69 mA cm−2 at 1.9 V versus the reversible hydrogen electrode (RHE) in 0.5 M H2SO4 under 1-sun illumination, with high stability and Фsaved, NPAC value, 4.36%. High photocurrent of water splitting device is originated from enlarged surface area of Sb2S3 nanocrystal film and electrical conduction improvement due to thermal annealing which reduced imperfections between nanoparticles.

Quantum dot light-emitting diodes (QLEDs) are expected to be the basis of next-generation displays and have consequently been extensively investigated with the aim of commercialization. Herein, QLE...

The cooling problem on integrated circuits (ICs) has emerged as the primary issue for higher performance of modern processors and three-dimensional ICs (3D ICs) in particular. Cooling systems with interlayer microchannels in 3D ICs have been widely studied as a promising cooling system for a high-performance processor. However, two-phase cooling systems for 3D ICs cooling have rarely been studied especially in interlayer microchannel structures. In this paper, we report a comparative study on cooling performance of single-phase cooling with water and two-phase cooling with R134a in an interlayer microchannel. The microfluidic and heat transfer problem was solved by using ANSYS Fluent 16.1. Contrary to the general view that two-phase cooling is better than single-phase cooling, we found that two-phase cooling with R134a is more efficient only in the heat flux of below 12 kW/m2 than single-phase cooling with water. The critical heat flux (CHF) was the main limitation of two-phase cooling to deal with a higher heat flux at a given mass flux.

Herein, we demonstrate that two-dimensional (2D) CdSeS quantum dot monolayers (QDM) can strongly influence efficient charge transport and charge separation, improving the performance of inverted polymer solar cells (iPSCs). Also, for the first time we report the electronic band structure of CdSeS and CdSeS@ZnS QDs and an effective approach to apply the 2D QDM as an effective electron transport layer in iPSCs from work function studies. The iPSCs with the 2D CdSeS QDM showed maximum power conversion efficiencies of 8.83%, which were 26% higher than the reference. Ultraviolet photoelectron spectroscopy and time-correlated single photon counting (TCSPC) measurements were performed to confirm the charge separation and electron transport behavior in the iPSCs with 2D QDMs. The PL decay time of the iPSCs with the CdSeS QDM at 720 nm was ∼60 ps, which is much faster than that of the iPSCs without the 2D QDM. The enhanced photovoltaic performance of the iPSCs with the 2D CdSeS QDM can be attributed to the effective charge separation and electron transport performance due to the high built-in voltage and fast exciton decay time from the 2D QDM.

As promising photo-absorbing materials for photovoltaics, organic–inorganic hybrid perovskite materials such as methylammonium lead iodide and formamidinium lead iodide, have attracted lots of attention from many researchers. Among the various factors to be considered for high power conversion efficiency (PCE) in perovskite solar cells (PSCs), increasing the grain size of perovskite is most important. However, it is difficult to obtain a highly crystalline perovskite film with large grain size by using the conventional hot-plate annealing method because heat is transferred unidirectionally from the bottom to the top. In this work, we presented radiative thermal annealing (RTA) to improve the structural and electrical properties of perovskite films. Owing to the omnidirectional heat transfer, swift and uniform nuclei formation was possible within the perovskite film. An average grain size of 500 nm was obtained, which is 5 times larger than that of the perovskite film annealed on a hot-plate. This perovskite film led to an enhancement of photovoltaic performance of PSCs. Both short-circuit current density and PCE of the PSCs prepared by RTA were improved by 10%, compared to those of PSCs prepared by hot-plate annealing.

Molybdenum disulfide (MoS2) has been extensively used as a hole transport layer in many inverted polymer solar cell devices. However, its potential as an electron transport layer in a solar cell device has rarely been reported. In this paper, we demonstrate an iPSC with enhanced photovoltaic performance by the introduction of a MoS2 nanosheet (NS) interlayer. Herein, MoS2 NS thin films were uniformly deposited on a polyethylenimine ethoxylated polymer by an electrostatic interaction. The MoS2 NS interlayer in the iPSC device plays important roles as a sub-photo sensitizer and an electron transport layer and provides effective charge separation for the enhancement of device performance. iPSCs with MoS2 NSs based on bulk heterojunction active materials such as P3HT:PC60BM, PTB7:PC71BM and PTB7-Th:PC71BM showed maximum power conversion efficiencies of 3.54%, 8.12%, and 9.08%, respectively, which were 27%, 11%, and 15% higher than those of the reference, respectively. Furthermore, the enhanced photovoltaic performance and electron transport mechanism of the iPSCs with the MoS2 NSs were confirmed experimentally using finite-difference-time-domain modeling and time-correlated single photon counting (TCSPC) measurements. The computational simulation results showed that the light absorption of the iPSCs with the MoS2 NS interlayer was slightly better than that of the iPSCs without the MoS2 NS interlayer. The electron decay time of PTB7:PC71BM with the MoS2 NS interlayer at a wavelength of 700 nm was reduced to 60 ps from 100 ps of PTB7:PC71BM without the MoS2 NS interlayer. The efficient light absorption and electron transfer characteristics of MoS2 NSs significantly improved the photovoltaic conversion performance of the iPSC devices.

In this paper, we present the development of a solution-processed photovoltaic structure designed to convert human body thermal radiation into electricity. An active layer composed of a layer of isopropylamine-capped lead sulfide (PbS) quantum dots (QDs) covered with a layer of lithium chloride (LiCl) on top is sandwiched between a substrate and an aluminum contact. Experimental measurements reveal that the device was sensitive to infrared radiation with energies lower than the optical bandgap energy of the incorporated nanocrystals (Eg = 1.26 eV), allowing one to harvest thermal radiation from a human body. We used a conceptually different approach to harvest this radiation by intentionally introducing mid-gap states to the lead sulfide quantum dots through passivation with isopropylamine and likely enabling a multi-step photon absorption mechanism.

Cost-effective, abundant, and non-toxic SnS nanosheet semiconductors can be used as water-splitting cells. Herein, a photoanode based on high-purity and highly crystalline SnS nanosheets was fabricated. We used sodium thiosulfate (Na2S2O3·5H2O) and stannous chloride (SnCl2·2H2O) as the tin and sulfur source materials, in place of SnCl4 and H2S gas, respectively, which have been used in previous studies. This gas-free fabrication process represents a new, environment-friendly fabrication method that can reduce the manufacturing cost of SnS nanosheets. The fabricated samples were characterized via X-ray diffraction, ultraviolet-visible spectroscopy, XPS, scanning electron microscopy, and Raman analyses. The XPS result indicated no Sn0 or Sn4+ in the S3 nanosheet, the nanosheet was SnS. These results with XRD show that the SnS nanosheet has high phase purity and crystallinity. Its direct optical band gap is 1.31 eV, and its lattice parameters are similar to those of standard SnS. The SnS nanosheet-based photoanode exhibited a maximum saturation photocurrent of 6.86 mA cm−2 at 0.57 V versus Ag/AgCl, with high stability. The most effective photocurrent for the photocatalytic water-splitting cell is attained with an increase in the surface area and developed electrical conduction. This is attributed to thermal annealing, which eliminates nanoparticle imperfections. This study confirms that SnS nanosheets are excellent candidates for water-splitting applications.

Perovskite solar cells (PSCs) have attracted immense attention owing to their outstanding power conversion efficiency (PCE). However, their counter electrodes are commonly produced by evaporating metals, such as Ag and Au, under high vacuum conditions, which make the PSCs costly, thereby limiting their large-scale production. In this study, a free-standing hybrid graphene/carbon nanotube film was carefully designed to replace noble metal PSC counter electrodes to reduce the cost and increase the stability of PSCs. A highly conductive and stable hybrid carbon thin film can be easily transferred to the various desired substrates by a simple rolling process. The PSCs with hybrid graphene/carbon nanotube films showed a high PCE of 15.36%. Moreover, the devices exhibited excellent stability and could retain 86% of their initial PCE after storage for 500 h in a high-moisture atmosphere (RH 50%). The outstanding stability of PCEs can be attributed to the efficient moisture blocking by the multilayered graphene/carbon nanotube present in the hybrid film. The thin, flexible, and easy-to-synthesize free-standing hybrid graphene/CNT film with high conductivity showed great potential for realizing the low-cost production of highly stable PSCs.

A novel hierarchical solution-processed fractional structured molybdenum oxide (MoO3) catalyst is fabricated from tricarbonyltris (propionitrile) molybdenum and used as the counter electrode of all-solid-state fiber-shaped dye-sensitized solar cells (S-FDSSC). The Tafel plot results and electrical impedance spectroscopy suggest that the use of the fractional structured MoO3 catalyst enhances the efficiency of the reduction of I3− to 3I− at the counter electrode/electrolyte interface. Because of the improvements of the short-current circuit and fill factor, the power conversion efficiency of the MoO3-modified S-FDSSC improves by 60% compared with that of the reference S-FDSSC. In addition, because of the robust fractional structure of MoO3, the MoO3-modified S-FDSSC maintains 90% and 95% of efficiency after 350-fold bending and the incident light angle dependency test, respectively. At 65% humidity and at 65 °C, the power conversion efficiency of the MoO3-modified device decreases by

Flexible sensors composed of carbon nanostructures and elastic materials have been developed for healthcare monitoring, environmental monitoring, disposable biochemical or electrochemical sensors, and many other applications. Fabrication approaches for such sensors and their advantages and current issues related to patterning high‐performance flexible sensors are reviewed. A focus is placed on patterning techniques for carbon‐based flexible sensors including carbon nanotubes, graphene, and other carbon nanostructures. First, novel patterning techniques for nanomaterials are described, along with their current challenges. Next, emerging flexible sensors including humidity, temperature, strain, and pressure sensors are discussed. Finally, the challenges and perspectives for flexible sensors are addressed.

We determine the influence of substitutional defects on perovskite quantum dots through experimental and theoretical investigations. Substitutional defects were introduced by trivalent dopants (In, Sb, and Bi) in CsPbBr3 by ligand-assisted reprecipitation. We show that the photoluminescence (PL) emission peak shifts toward shorter wavelengths when doping concentrations are increased. Trivalent metal-doped CsPbBr3 enhanced the PL quantum yield (~10%) and air stability (over 10 days). Our findings provide new insights into the influence of substitutional defects on substituted CsPbBr3 that underpin their physical properties.

Microelectrodes for detection of chemicals present several advantages over conventional sized electrodes. However, rapid and low-cost fabrication of microelectrodes is challenging due to high complexity of patterning equipment. We present the development of a low-cost, customizable inkjet printer for printing nanomaterials including carbon nanotubes for the fabrication of microelectrodes. The achieved spatial resolution of the inkjet printer is less than 20 µm, which is comparable to advanced commercially available inkjet printers, with the advantage of being low-cost and easily replicated.

Electrical stimulation technology has advanced from cardiac pacemakers towards cochlear implants, physical rehabilitation, and treatment for Parkinson&rsquo, s and other diseases. Electrical stimulation parameters, such as waveform, amplitude, and stimulation frequency, have been shown to affect neurostimulation properties. However, the effect of signal time rate of change on electrical stimulation applications has not been studied, and there are no stimulators that specifically allow the study of these effects. A novel pulse generator circuit is presented and characterized. An analytical expression is derived from the circuit, that allows for the design of pulse parameters, such as maximum amplitude voltage, time for peak amplitude, and stimulation duration. The analytical expression is verified to match design values and measurements in an electrical model and phosphate-buffered saline (PBS) solution. The circuit is shown to operate at variable output stimulation frequencies, and an expression is derived in order to determine the limit of the output stimulation frequency. The pulse generation circuit is thought to be the first dedicated output pulse generator for research of the effect of signal time rate of change on electrical stimulation applications such as neurostimulation.

Organic–inorganic lead halide perovskite is emerging as a potential emissive material for light emitting devices, such as, light emitting diodes (LEDs) and lasers, which has emphasized the necessity of understanding its fundamental opto-physical properties. In this work, the temperature-dependent photoluminescence of CH3NH3PbBr3 perovskite quantum dots (QDs), polycrystalline thin film (TF), and single crystal (SC) has been studied. The optophysical properties, such as exciton–phonon scattering, exciton binding energy, and exciton decay dynamics, were investigated. The exciton–phonon scattering of perovskite is investigated, which is responsible for both PL line width broadening and nonradiative decay of excitons. The exciton binding energy of QDs, TF, and SC were estimated to be 388.2, 124.3, and 40.6 meV, respectively. The observed main exciton decay pathway for QDs is the phonon assisted thermal escape, while that for TF and SC was the thermal dissociation due to low exciton binding energy.

In this study, we present efficient semi-transparent solar cells with enhanced performance at low intensity illumination via the incorporation of emissive quantum clusters consisting of 22 Au atoms. The inclusion of Au22 quantum clusters (Au22-QCs) in semi-transparent solar cells led to a substantial reduction of the dependence on the incident light intensity as well as an increase in device efficiency. For the control semi-transparent solar cell, which has ~ 25% transparency, there was a 35% drop in efficiency with a light intensity decrease of 40% (0.6 sun). However, for the semi-transparent solar cell with Au22-QCs, there was only a 15% drop in efficiency under 0.6 sun irradiation. Less dependence on incident light intensity can be a great advantage in the practical use of semi-transparent solar cells. The change in the intensity of the incident light can also be caused by simply changing the angle of the light and device. Thus, the performance of general solar cells is strongly dependent on the angle of incident light. However, such angle dependence was effectively suppressed in solar cells with Au22-QCs. Furthermore, less dependence on the angle of incidence light offered a great advantage in driving flexible solar cells. The performance difference between the flat state and bending state was significantly reduced in our semi-transparent flexible solar cell with Au22-QCs.

We have achieved high-efficiency polycrystalline perovskite light-emitting diodes (PeLEDs) based on formamidinium (FA) and cesium (Cs) mixed cations without quantum dot synthesis. Uniform single-phase FA1–xCsxPbBr3 polycrystalline films were fabricated by one-step formation with various FA:Cs molar proportions; then the influences of chemical composition on film morphology, crystal structure, photoluminescence (PL), and electroluminescence (EL) were systematically investigated. Incorporation of Cs+ cations in FAPbBr3 significantly reduced the average grain size (to 199 nm for FA:Cs = 90:10) and trap density; these changes consequently increased PL quantum efficiency (PLQE) and PL lifetime of FA1–xCsxPbBr3 films and current efficiency (CE) of PeLEDs. Further increase in Cs molar proportion from 10 mol % decreased crystallinity and purity, increased trap density, and correspondingly decreased PLQE, PL lifetime, and CE. Incorporation of Cs also increased photostability of FA1–xCsxPbBr3 films, possibly due to...

Recently, all-inorganic perovskite quantum dots (PeQDs), CsPbX3 have become attractive because of their excellent optoelectronic properties and superior air/moisture stabilities compared with conventional organic–inorganic hybrid perovskites, and the application of CsPbX3 PeQDs to light-emitting devices (LEDs) has also become competitive. To enable the use of CsPbX3 PeQDs for thin-film-type perovskite quantum-dot LEDs (PeQLEDs), a paradox associated with the ligand property and surface passivation must be overcome during thin-film fabrication. A decline in the photoemission performance was observed at relatively low amounts of surface-passivating ligands, while the quality of the thin film deteriorated in the presence of excessive ligands. To address this conflict, in this study, the performance of PeQLEDs based on CsPbX3 fabricated by a novel method involving solid-state ligand exchange (SLE) with aromatic acid/amine was investigated. Using this strategy, most of the excess ligands were removed while pre...

Perovskite nanoparticle (NP)-embedded copolymer particles are prepared via self-emulsion polymerization (SEP) and a vapor-assisted solution process (VASP). The prepared particles are self-assembled to form photonic bandgaps (PBs), which modified the photoluminescence (PL) spectrum of the embedded perovskite NPs to have an enhanced PL intensity and a reduced full width at half maximum (FWHM).

Polydimethylsiloxane (PDMS) has been widely used in fabricating microfluidic devices for prototyping and proof-of-concept experiments. Due to several material limitations, PDMS has not been widely adopted for commercial applications that require large-scale production. This paper describes a novel injection-molded plastic array 3D culture (IMPACT) platform that incorporates a microfluidic design to integrate patterned 3D cell cultures within a single 96-well (diameter = 9 mm) plate. Cell containing gels can be sequentially patterned by capillary-guided flow along the corner and narrow gaps designed within the 96-well form factor. Compared to PDMS-based hydrophobic burst valve designs, this work utilizes hydrophilic liquid guides to obtain rapid and reproducible patterned gels for co-cultures. When a liquid droplet (i.e. cell containing fibrin or collagen gel) is placed on a corner, spontaneous patterning is achieved within 1 second. Optimal dimensionless parameters required for successful capillary loading have been determined. To demonstrate the utility of the platform for 3D co-culture, angiogenesis experiments were performed by patterning HUVEC (human umbilical endothelial cells) and LF (lung fibroblasts) embedded in 3D fibrin gels. The angiogenic sprouts (with open lumen tip cells expressing junctional proteins) are comparable to those observed in PDMS based devices. The IMPACT device has the potential to provide a robust high-throughput experimental platform for vascularized microphysiological systems.

Elimination of charge trapping at defects is highly challenging for poly-crystalline organometal halide perovskites. Here, we report a new architecture for reinforcing the built-in electric field (Ein) across the photoactive layer with a pair of strong electric dipole layers (EDLs). The paired EDLs significantly intensify the Ein across the perovskite layer, resulting in suppressed charge trapping of photogenerated charges. As a result, our low-temperature processed P–I–N planar PeSC devices using the paired EDLs exhibit a higher power conversion efficiency (ηmax ∼ 19.4%) and a smaller device-to-device variation with a standard deviation (S.D.) of 0.70%, which far surpass those (ηmax ∼ 17.8%, S.D. ∼ 1.1%) of the devices with typical charge transport layers.

Liquid embolic agents are considered the most promising for various embolization procedures because they enable deep penetration. For realizing effective procedures, the delivery of liquid embolic agents should be guided under X-ray imaging systems and the solidification time should be optimized for the specific indication. The biocompatibility of embolic agents is also crucial because they remain in the vessel after embolization. In this study, we synthesized new biocompatible embolic agents based on tantalum ethoxide. Tantalum alkoxide liquid embolics (TALE) possess the radiopacity for fluoroscopy and can control the penetration depth by modifying the sol-gel kinetics. Furthermore, TALE can serve as drug carriers for synergistic treatment. Using these excellent characteristics, we demonstrated that TALE agents can be used in various situations including the transarterial chemoembolization of hepatocellular carcinoma and embolotherapy of massive bleeding from the femoral artery. This article is protected by copyright. All rights reserved.

Herein, we report a novel micro-flower lamellar structured α-MoO3 counter electrode for solid-state fiber-shaped dye–sensitized solar cells. The α-MoO3 sol-gel precursor, which is Tricarbonyltris (propionitrile) molybdenum, fabricates the α-MoO3 microstructures by applying Joule heating. Cyclic voltammetry and Tafel polarization results indicate that the α-MoO3 counter electrode with micro-flower lamellar has higher catalytic activity than pristine Pt. Therefore, based on the efficient reduction reaction of triiodide ions, the novel α-MoO3 counter electrode with flower-structure could enhance short-circuit current with high power conversion efficiency (PCE). Furthermore, the device with the α-MoO3 counter electrode provides better device stability and flexibility. Under 500 bending cycles, the PCE of the novel α-MoO3 counter electrode device maintains more than 90% characteristics, while the bare Pt device reduces to 70%.

In this paper, we explore the impact of isopropylamine (IPAM) as a short ligand on a solution-processed infrared photodetector and a photovoltaic device using lead sulfide (PbS) colloidal quantum dots. Original oleic acid capping is replaced by isopropylamine through a solution-phase ligand exchange process. Then a blend of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] or MEH-PPV and the isopropylamine-capped PbS colloidal quantum dots is prepared for a photosensitive layer sandwiched by two different electrodes. Results illustrate that contribution of isopropylamine can improve the responsivity of a photodetector and enhance the photovoltaic performance by increasing the open circuit voltage and short circuit current.

Fine particles within porous media may migrate with the flowing fluid and cause bridging or clogging in the pore space. Bridging and clogging reduce the flow permeability of porous media, which has a significant influence on petroleum engineering applications such as water and oil extraction, sand production, and gas production from hydrate-bearing sediments. Although the migration of fine particles and its impact on bridging and clogging have been investigated for a single-phase flow, it has not been understood clearly for a multi-phase flow. This work reports an approach using microfluidic pore models to study the migration of fine particles and the bridging/clogging behavior in a structure mimicking porous media. Results from the microfluidic model show that: (1) fine particles accumulated along the water and gas (CO2) interface; (2) fine particle concentrations in pores locally increased due to the accumulated particles at the interface, and (3) consequently bridging and clogging occurred in the pore throat. Findings from this work provide a starting point in understanding complex phenomena including a reduced flow permeability of porous media on a fluid containing fine particles for a variety of petroleum engineering applications. 2017, Springer-Verlag GmbH Germany. Acknowledgement This research was made possible by NPRP Grant # NPRP8-594-2-244 from Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. Scopus

This paper presents a two dimensional force sensor fabricated on PDMS nanocomposite, with patterned carbon nanotubes (CNTs) acting as a force sensing unit. A novel fabrication method is composed of inkjet printing of CNTs onto polyethylene terephthalate (PET) and subsequent transfer of the CNT patterns to PDMS, resulting in a CNT-elastomer nanocomposite that is flexible and conductive. This approach allows patterning of a large-area conductive carbon nanotube pattern on PDMS. The achieved sheet resistance of the transferred patterns on PDMS was 1.2k/ when printed 35 times, using an office inkjet printer. The fabricated sensor changes its resistance when force is applied perpendicularly to the sensor. A two dimensional force sensor, working on the principle of compression-induced deformation was fabricated and characterized with achieved resolution of four sensing cells per cm2. Additionally, we demonstrate a two dimensional flexible force sensor capable of creating a pressure map of the applied force. Together with inkjet printing, this pattern transfer process represents a highly effective patterning technique for embedding carbon nanotubes in PDMS. Display Omitted A transfer printing technique has been developed to pattern embedded carbon nanotubes onto PDMS.Patterns show good uniformity, forming an embedded CNT network.A highly flexible two dimensional force sensor has been demonstrated, showing the pressure map applied.

(E)-6,6′-Dibromo-1,1-bis(2-octyldodecyl)-(3,3′-biindolinylid-ene)-2,2′-dione and/or 2,5-bis(2-octyldodecyl)-3,6-di(5-bromothien-2-yl)pyrrolo[3,4-c]pyrrole-1,4-(2H,5H)-dione and their tBoc-counterparts were propagated with 2,5-bis(tributylstannyl)thiophene in a molar ratio of 0.8 : 0.2 : 1.0 to release P(ODIDT-BID), P(ODIDT·BDPP), P(ODDPPT·BID) and P(ODDPPT·BDPP) as a new series of random conjugated polymers (RCPs) bearing a large number of octyldodecyl chains to ensure solubility and a small number of thermocleavable tBoc function to cast H-bonding upon heating up to 220 °C. All new polymers were synthesised via Pd catalysed Stille cross-coupling methodology in high yields and reasonable average molecular weights. The cast polymer films exhibited considerable red-shifted UV-vis absorption spectra and a further red-shift was also obtained in the thermal annealed films (at 220 °C for 30 min), which reflected the increasing of crystalline structure. The formation of H-bonding in these polymers was investigated using X-ray diffractometry (XRD) measurements. The field-effect mobilities of these polymers were investigated in the configuration of bottom-gate and bottom-contact (BGBC) field-effect transistors (FETs). The results from FETs indicated that the crystalline structure of RCPs exhibited reasonable FET mobilities with 1.17 × 10−3 cm2 V−1 s−1 for P(ODDPPT·BID) and 1.41 × 10−3 cm2 V−1 s−1 for P(ODDPPT·BDPP).

This paper proposes a simple and rapid fabrication of a glucose sensor based on inkjet printing method. A commercially available inkjet printer is used to print carbon nanotubes and polyaniline nanowires for patterning low sheet resistance electrodes and a chemiresistive glucose sensing area, respectively. Enzyme glucose oxidase, in conjunction with platinum nanoparticles were also incorporated into the chemiresistive sensor to generate a two-step catalytic process: in the first step, glucose is catalyzed by the oxidase to produce hydrogen peroxide as a byproduct, and in the second step, platinum nanoparticles catalyze hydrogen peroxide to produce hydroxide ions which causes a local pH change near the site of reaction. Since the conductivity of polyaniline is known to be pH-responsive, the polyaniline layer serves as a chemiresistive sensor to detect the H2O2 concentration which subsequently leads to the quantification of the glucose concentration. The developed inkjet-printed glucose sensor was able to achieve a detection limit of 2 mM and a good linear relationship between current measurements and glucose concentration was obtained. The results indicate that the proposed method to print a simple, rapid, and disposable glucose sensing device can lead to the development of an on-demand printable point-of-care diagnostic kit for glucose measurement.

Organometallic halide perovskite films were treated with novel facile solvent vapour annealing to control crystal grain size as well as the crystallinity of perovskite. As both polarity and vapour pressure of the treatment solvent for perovskite increase, luminance increases and the wavelength of the photoluminescence emission peak decreases due to enhanced crystallinity and reduced grain size.

We propose a novel method to pattern the charge recombination layer (CRL) with a low-temperature solution-processable ZnO layer (under 150 &deg, C) for organic solar cell applications. Due to the optimal drying process and thermal annealing condition, ZnO sol-gel particles formed a three-Dimensional (3D) structure without using a high temperature or ramping method. The generated 3D nano-ripple pattern showed a height of around 120 nm, and a valley-to-valley distance of about 500 nm. Based on this newly developed ZnO nano-ripple patterning technique, it was possible to pattern the CRL without damaging the underneath layers in tandem structure. The use of nano-ripple patterned ZnO as the part of CRL, led to the concomitant improvement of the power conversion efficiency (PCE) of about 30%, compared with non-patterned CRL device.

Ultra-thin and large-area silicon wafers with a thickness in the range of 20-70 μm, were produced by spalling using a nickel stressor layer. A new equation for predicting the thickness of the spalled silicon was derived from the Suo-Hutchinson mechanical model and the kinking mechanism. To confirm the reliability of the new equation, the proportional factor of stress induced by the nickel on the silicon wafer, was calculated. The calculated proportional factor of λ = 0.99 indicates that the thickness of the spalled silicon wafer is proportional to that of the nickel layer. A similar relationship was observed in the experimental data obtained in this study. In addition, the thickness of the stressor layer was converted to a value of stress as a guide when using other deposition conditions and materials. A silicon wafer with a predicted thickness of 50 μm was exfoliated for further analysis. In order to spall a large-area (150 × 150 mm2 or 6 × 6 in2) silicon wafer without kerf loss, initial cracks were formed by a laser pretreatment at a proper depth (50 μm) inside the exfoliated silicon wafer, which reduced the area of edge slope (kerf loss) from 33 to 3 mm2. The variations in thickness of the spalled wafer remained under 4%. Moreover, we checked the probability of degradation of the spalled wafers by using them to fabricate solar cells; the efficiency and ideality factor of the spalled silicon wafers were found to be 14.23%and 1.35, respectively.

Forming heterojunctions is a traditional approach for improving the performance of semiconducting nanomaterials. However, using a biological nanostructure to achieve such a goal has rarely been studied. Here we showcase a novel biohybrid junction comprising a functional nanobiomaterial (bacteriophage) and a semiconductor nanomaterial (perovskite quantum dots). We found that M13 bacteriophage, genetically modified to bear increased negative charges, could assist the growth of cubic cesium lead bromide (CsPbBr3) perovskite quantum dots with a size of 13.25 ± 2.69 nm. The M13 bacteriophage further functioned as a scaffold for the assembly of the formed CsPbBr3 quantum dots into a bacteriophage-perovskite biohybrid with a photoluminescence quantum yield of 40.1%, 2.99-fold higher than that of conventional CsPbBr3 quantum dots (13.4%). In addition, compared to the conventional perovskite quantum dots, the perovskite quantum dots in the bacteriophage-based biohybrids exhibited a decreased full width at half maximum (FWHM) of the photoluminescence, indicating that the biohybrids are a better color gamut for light-emitting device applications. Such high optical performance arose from the ordered arrangement of the quantum dots by the bacteriophage, which further affected the charge density due to the interaction between the bacteriophage and CsPbBr3 surface. The materials lifetime of the M13 bacteriophage-assisted perovskite quantum dots was also 1.76 times greater than that of the conventional counterparts without the assistance of bacteriophages due to the reduced valence energy level in the biohybrids. The experiment using bacteriophage with artificially increased surface charge density through genetic manipulation proved our assumption that the surface charge density of the bacteriophage contributes to the stabilization of perovskite quantum dots. The light-emitting diode (LED) with perovskite quantum dots assembled and functionalized by bacteriophage exhibited a 17-fold higher maximum luminance than that of conventional CsPbBr3 quantum dots. This work demonstrates a novel nanobiotechnological approach to the production and assembly of perovskite quantum dots for light-emitting applications.

Fiber-shaped solar cells have attracted significant attention for their potential applications in portable and wearable electronics. Developing highly efficient and stable counter electrodes (CEs) to replace rare and expensive noble metals in dye-sensitized solar cells (DSSCs) is a research challenge. The low cost, excellent activity, and stability of carbon materials make them the most qualified noble-metal-free CEs for the commercialization of photovoltaic devices. In this study, we incorporated a carbon nanotube yarn (CNTY) as a CE for efficient and stable solid-state fiber-shaped DSSCs. After device optimization, the power conversion efficiency with the CNTY fiber-shaped DSSCs was approximately 4.00%, which is comparable to that of devices with platinum electrodes (2.64%). The superior mechanical property and performance stability after repeated bending, cleaning, and high output voltage for in-series connection suggest that the proposed CNTY fiber-shaped DSSCs may find applications as flexible power sources in next-generation flexible/wearable fiber electronics and energy textiles.

Fluorescent portable monitoring systems provide real-time and on-site analysis of a sample solution, avoiding transportation delays and solution degradation. However, some applications, such as environmental monitoring of bodies of water with algae pollution, rely on the temperature control that off-site systems provide for adequate solution results. The goal of this research is the development of a temperature stabilization module for a portable fluorescent sensing platform, which is necessary to prevent inaccurate results. Using a Peltier device-based system, the module heats/cools a solution through digital-to-analog control of the current, using three surface-mounted temperature modules attached to a copper cuvette holder, which is directly attached to the Peltier device. This system utilizes an in-house algorithm for control, which effectively minimizes temperature overshooting when a change is enacted. Finally, with the use of a sample fluorescent dye, Rhodamine B, the system’s controllability is highlighted through the monitoring of Rhodamine B’s fluorescence emission decrease as the solution temperature increases.