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We demonstrated the sensing properties and adsorption mechanism of NO2 molecules of monolayer graphene and multilayer graphene encapsulated ZnO QDs for NO2 gas adsorption. The gas response value of ZnO-multilayer graphene (ZMLG) QDs was approximately 23 % and 7.2 and 25.5 times higher than that with ZnO-monolayer graphene (ZG) and ZnO QDs, respectively. The surface potential change of ZMLG QDs increased up to 14.25 times compared to ZnO QDs and 6.33 times increased compared to ZG QDs. We proposed an accurate adsorption mechanism for the improvement of the detection behavior that is occured by covering the graphene shells into ZnO QDs by the Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), and SKPM measurement. These results are expected to increase the accuracy of gas sensor characteristic analysis.

Objective To confirm the feasibility of visualizing upper and lower proximal lacrimal canaliculi (LC) using spectral-domain optical coherence tomography (SD-OCT). Animals studied Eight eyes of four normal Beagle dogs. Procedures To obtain an upper proximal LC image, the head was turned in the opposite direction to the eye being imaged, and the medial part of the upper eyelid was everted to expose the LC. To obtain a lower LC image, the lower eyelid was everted just below the punctum. Using "angle mode", the scan line was placed parallel on the long axis of the LC. The inlet LC width (LCW) was measured. Artificial tears (AT) were instilled, and LCW was compared before and after AT instillation. Additionally, the return time to the initial LCW inlet width was recorded. Results Before AT instillation, there was a significant difference between the mean upper and lower LCW (91.8 ± 3.2 µm and 110.1 ± 8.4 µm, respectively). After AT instillation, the mean upper and lower LCW were 236.9 ± 27.7 µm and 238.4 ± 30.4 µm, respectively. Significant differences in the LCW before and after AT instillation in both the upper and lower LCWs were observed. The mean return time of the upper and lower LCW to their initial widths after AT instillation was within 4 min. Conclusions Spectral-domain optical coherence tomography was an effective method for providing high-resolution images of the upper and lower proximal LC. This method enables observation of LC changes after instillation of eyedrops in veterinary clinical practice.

We demonstrated the thermally robust reduced graphene oxide (rGO)/boron nitride nanotube (BNNT) papers and their application in electromagnetic interference shielding. In order to overcome the thermal durability shortcomings of electromagnetic wave shielding paper based on rGO nanomaterial, rGO/BNNT electromagnetic interference (EMI) shielding paper having excellent thermal durability could be manufactured using BNNT nanomaterials having excellent chemical and thermal stability at high temperature. With the addition of a little BNNT, the durability against temperature can be increased by more than two times while there is little reduction in EMI performance.

Transition metal oxide has been attracting significant attention as a potential alternative anode materials for high-performance lithium-ion batteries. However, the materials still suffer from poor performance due to the large volume expansion during reversible electrochemical reaction between the materials and Li ions. Here, we report on successfully synthesized graphene encapsulated Co3O4 (GE-Co3O4) quantum dots (QDs) by a facile chemical reaction. We also demonstrate an improved performance in Li storage with GE/Co3O4 by suppression of volume expansion during charge/discharge processes. To evaluate the electrochemical characteristics for the lithium storage the composites were examined by cyclic voltammetry and charge/discharge process. The GE-Co3O4 showed a large reversible capacity of 820 mA h/g at a constant current density of 1000 mAg−1 even after 100 cycles and excellent rate capacity and cyclic stability compared to pristine Co3O4 QDs. The encapsulated graphene shell can obstruct the pulverization by inhibiting the volume expansion of Co3O4 QDs, which was supported by the fact that the morphology and structure of GE-Co3O4 QDs was not significantly changed after 100 cycles. We also confirmed through scanning Kelvin probe microscopy, transmittance electron microscopy, and energy-dispersive X-ray spectrometer that the morphology of GE-Co3O4 QDs was maintained whereas that of Co3O4 QDs was almost fully decomposed. The encapsulation of graphene can play important roles such as suppression of volume expansion and producing a sufficient opposing force to aggregation during the cycles, resulting in a long stable life cycle.

Recently, research on the use of additives in photoactive layers to improve the efficiency of solar cells has continued to be conducted. Among them, carbon-based additives serve to increase a device's efficiency by simply and effectively improving the carrier movement. In this work, inverted polymer solar cells (iPSCs) are fabricated based on a blend of PTB7-Th:PC71BM and PTB7:PC71BM bulk heterojunction as photoactive materials using mixed additives of 4Cl-carbon-based contorted hexabenzocoronene (4Cl-cHBC). The 4Cl-cHBC additives, a kind of contorted polycyclic aromatic hydrocarbon, added to bulk heterojunction in the iPSC devices, provide a cocrystal modifier and effective charge separation to enhance device performance. The reason for this efficiency improvement is that cocrystal is formed due to a combination between 4Cl-cHBC and the PTB7-Th:PC71BM bulk heterojunction, which reduces bimolecular recombination in the device and significantly increases short-circuit current and fill factor. The RS and RSh values of iPSCs based on PTB7-Th:PC71BM with and without the 4Cl-cHBC additives decreased from 7.0 Ω cm2 to 4.0 Ω cm2, and increased from 813 Ω cm2 to 1226 Ω cm2, respectively. The calculated average carrier lifetimes at 500 nm for PTB7-Th:PC71BM and PTB7-Th:PC71BM with 4Cl-cHBC additives are 4.46 ps and 3.06 ps, respectively. The carrier lifetimes show that the charge separation of PTB7-Th:PC71BM with 4Cl-cHBC additives is more than 45% faster. As a result, the iPSCs based on the blend of PTB7-Th:PC71BM and PTB7:PC71BM with 4Cl-cHBC additives showed maximum power conversion efficiencies of 9.46 and 8.62%, which were 20.6 and 19.95% higher than those of the reference, respectively.

Environmentally friendly metal oxide quantum dot (QD) nanostructures have become attractive alternative materials for replacing QDs containing toxic elements of Cd and Pb. Although many attempts have been proposed for optoelectronic applications of hybrid metal oxide QDs with tailored opto-electronic properties, the fabrication of heterogeneous QD–fullerene hybrids as an emissive material has been studied little for optoelectronic devices. Herein, we report the preparation of ZnO–fullerene C70 (ZnO–C70) QDs by a facile chemical reaction with a zero length linker and demonstrate whitish light-emitting diodes by fullerene induced multicolor emission from the ZnO–C70 QD heterostructure. The electroluminescence (EL) is attributed to three new emission features in the visible region that originate from the electron transitions from three split lowest unoccupied molecular orbital levels of C70 molecules to the valence band of ZnO QDs. Compared with photoluminescence, the EL emission was red-shifted by 50–130 meV due to the interaction between ZnO–C70 QDs in the solid state. The energy levels of C70 were also suitably aligned to those of ZnO QDs with a lower electron transfer barrier of 0.22 eV, which offers an advantageous route for electron transport. Consequently, the environmentally friendly ZnO–C70 QDs with extraordinary properties promise great potential for use as novel encapsulating materials in the field of opto-electronic applications adopting QDs.

OBJECTIVE To compare the measurements of iridocorneal angle parameters between spectral domain optical coherence tomography (SD-OCT) and ultrasound biomicroscopy (UBM) in dogs. ANIMALS STUDIED AND PROCEDURES A total of 47 eyes of dogs were scanned at the temporal limbus using SD-OCT and UBM. Iridocorneal angle (ICA) and angle opening distance (AOD) were measured from the obtained images accordingly. The intra-observer and inter-observer reproducibility were evaluated using the intraclass correlation coefficient. To evaluate intra-observer reproducibility, measurements of the first and second grading from the first examiner were compared. To evaluate inter-observer reproducibility, measurements between the two examiners were compared. Agreement between ICA and AOD for SD-OCT and UBM was evaluated using Bland-Altman plots. RESULTS In the first grading, the mean ICA and AOD for SD-OCT were 31.4 ± 6.4° and 641.4 ± 270.8 µm, respectively. The mean ICA and AOD for UBM were 32.0 ± 4.8° and 700.4 ± 238.8 µm, respectively. For ICA and AOD measurements, intra-observer reproducibility was excellent for both devices, whereas inter-observer reproducibility was excellent for SD-OCT and good for UBM. The mean difference in ICA between SD-OCT and UBM was 0.6° with a limit of agreement (LoA) span of 18.9°. The mean difference in AOD between SD-OCT and UBM was 58.9 µm with a LoA span of 804.4 µm. CONCLUSIONS Spectral domain optical coherence tomography is an effective non-contact imaging modality for the evaluation of canine iridocorneal angle parameters in a clinical setting. Reproducibility of measurements obtained is comparable or superior to UBM, but values obtained by SD-OCT and UBM for AOD are not interchangeable between devices.

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.

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.

Epoxy adhesive was analyzed under long term thermal aging and mechanical properties and chemical degradation were observed by X-ray photoelectron spectroscopy (XPS). Long term thermal exposure of epoxy causes a noticeable reduction in adhesive properties. We developed a predictive model of temperature and time dependent aging. The temperature dependent aging behavior of epoxy adhesive shows good agreement with conventional Arrhenius equations. Using XPS analysis, we also discovered a correlation between chemical degradation and the adhesive properties. Decay of C–C bonding ratio induced chain-scission of epoxy adhesive; increase of total numbers of C–O and C═O induced oxidation of epoxy adhesive during thermal exposure.

The aggregation of zinc oxide nanoparticles leads to an increased absorbance in the ultraviolet-visible region by an induced light scattering effect. Herein, we demonstrate the inhibition of photoconversion activity in ZnO-graphene core-shell quantum dots (QD) (ZGQDs) agglomerated by 4-aminophenol (4-AP) used as a linker. The ZnO-graphene quantum dots (QD) aggregates (ZGAs) were synthesized using a facile solvothermal process. The ZGAs revealed an increased absorbance in the wavelengths between 350 and 750 nm as compared with the ZGQDs. Against expectation, the calculated average photoluminescence lifetime of ZGAs was 7.37 ns, which was 4.65 ns longer than that of ZGQDs and was mainly due to the high contribution of a slow (&tau, 2, &tau, 3) component by trapped carriers in the functional groups of graphene shells and 4-AP. The photoelectrochemical (PEC) cells and photodetectors (PDs) were fabricated to investigate the influence of ZGAs on the photoconversion activity. The photocurrent density of PEC cells with ZGAs was obtained as 0.04 mA/cm2 at 0.6 V, which was approximately 3.25 times lower than that of the ZGQDs. The rate constant value of the photodegradation value of rhodamine B was also decreased by around 1.4 times. Furthermore, the photoresponsivity of the PDs with ZGAs (1.54 &mu, A&middot, mW&minus, 1) was about 2.5 times as low as that of the PDs with ZGQDs (3.85 &mu, 1). Consequently, it suggests that the device performances could be degraded by the inhibition phenomenon of the photoconversion activity in the ZGAs due to an increase of trap sites.

We report on the in-situ chemical growth of unique core-shell quantum dots (QDs) with single layer graphene on the surface of CuO QDs and their structural, optical and electrical properties. The CuO/graphene QDs were synthesized through a simple and hydrothermal technique. In order to enhance performance electrochemical energy storages, we have developed core (active material)/shell (conductive material) type CuO/graphene QDs as electrode materials using the combined electrolytes (KOH + LiCl). As a result, the performance of electrochemical energy storages exhibits specific capacitance of 154 F g−1 at current density of 1 A g−1 and cycling stability with 84% capacitance retention after 3,000 cycles.

Hybrid organic-Red-Green-Blue (RGB) color quantum dots were incorporated into consolidated p(polymer)-i(RGB quantum dots)-n(small molecules) junction structures to fabricate a single active layer for a light emitting diode device for white electroluminescence. The semiconductor RGB quantum dots, as an intrinsic material, were electrostatically bonded between functional groups of the p-type polymer organic material core surface and the n-type small molecular organic material shell surface. The ZnCdSe/ZnS and CdSe/ZnS quantum dots distributed uniformly and isotropically surrounding the polymer core which in turn was surrounded by small molecular organic materials. In the present study, we have identified the mechanisms of chemical synthesis and interactions of the p-i-n junction nanocell structure through modeling studies by DFT calculations. We have also investigated optical, structural and electrical properties along with the carrier transport mechanism of the light emitting diodes which have a single active layer of consolidated p-i-n junction nanocells for white electroluminescence.

Transparent human hair-based textiles, which are founded on a natural resource, have been fabricated by an electrospinning technique. Transparent human hair-based textiles are very useful for transparent wearable electronics because they have unique optical properties in the visible light region such as transparency of over ∼85%. In order to apply wearable electronic devices with transparent textiles, we fabricated sandwich structures with transparent flexible light emitting diodes (LEDs) embedded in transparent nanofiber textile utilizing ZnO@graphene quantum dots (ZGQDs) and demonstrated the fabrication process and characterization of ZGQD LEDs with textiles. We believe that these results will inspire new methods in wearable electronics and raise the hope of achieving even higher efficiencies by means of development and control of transparent textile ordering.

The characteristics of a flexible write-once-read-many-times (WORM) memory fabricated with monolayered 0-dimensional (0D) CdSe–ZnS quantum dots (QDs) layers sandwiched between two insulating 2-dimensional (2D) hexagonal boron nitride (hBN) multilayers were investigated by electrical measurement method. The hBN/QDs monolayer/hBN structure was fabricated in a vertical stacked structure using a technique which control the formation of the QDs monolayer. QDs monolayer was formed by electrostatic interaction between the negative charge group on the CdSe–ZnS QDs surface and the positive charge group on the hBN surface. The device has a WORM characteristic due to the presence of QDs in the current-voltage (I–V) measurement. When a bias is applied, carriers were initially trapped by tunneling due to the QDs and then a conductive filament was formed in the hBN, which were not detrapped and exhibit characteristics of write-once-read-many-times memory. The maximum ON/OFF ratio of the current for the devices was as large as 4 × 10, and the endurance was 5 × 104 cycles, and a retention time was larger than 1 × 105 s. In order to explain the carrier transport mechanism and conductive filament of the WORM memory device caused by QDs, it through various methods such as I–V fitting data, simulation, and conductive AFM. Unlike the conventional conductive filament mechanism, through random diffusion such as Ag filament, the Au/hBN/QD/hBN/ITO/PET structures implemented a consistent conductive filament using Au metal and QDs active layer.

Optoelectronic devices with dual-function consisting of LEDs and OBDs, both containing ZnO QDs dispersed in a hybrid poly N-vinylcarbazole (PVK) and polymethylmethacrylate (PMMA) polymer layer, were fabricated on indium-tin-oxide (ITO)-coated glass substrates using a simple spin-coating technique. Transmission electron microscopy images showed that the ZnO QDs were distributed around the PVK and the PMMA. The laminated devices showed the electroluminescence of LEDs and the electrical bistabilities of OBDs. To make the OBDs into the LEDs, a PEDOT:PSS hole injection layer and a PVK hole transport layer were inserted between the active layers and the electrodes, respectively. Luminescence mechanisms of the LEDs and operating mechanisms of the OBDs are described on the basis of the experimental results.

We have developed a new and versatile three-dimensional (3D) porous and the conductive carbon spun fabric (CSF) structure and applied it to the current collector for advanced lithium-ion batteries (LIBs). The 3D porous CSF are manufactured from recycled oxidized polyacrylonitrile (Oxi-PAN) staple fibers via the spinning, the knitting, stabilization, and carbonization process in order. Furthermore, we have demonstrated the conductive T-shirts and gloves and investigated the structural, electrical, mechanical, and thermal properties of the CSF through various analytical methods including Joule heating simulation as well as the deformation simulation. The CSF with its 3D porous structure is applied as a current collector for advanced lithium batteries in order to replace the conventionally used metal-based current collector. During battery performances, the porous 3D network structure of the CSF provides effective diffusion pathway for lithium ions during the charge/discharge processes. Consequently, the CSF shows not only the improved cycling stability than that of the conventional aluminum current collector but also demonstrating high-rate performances at high percentage loading of active materials in the current collector. The pouch-type LIBs with the CSF/LiFePO4 composites electrode exhibits excellent mechanical stability and flexibility with showing a discharge capacity of 148.7 mA h g−1 at 2 C over 250 cycles over the 1200 times bending with a radius of 12 mm.

A new way to simultaneously grow carbon nanotubes (CNTs) and ultrathin graphite on copper (Cu) foils has been investigated. This one-step growth process yields three-dimensional networks of CNTs on graphitic layers (3D CNTs/G) on Cu foils. Their synthesis conditions and growth mechanism are discussed in detail taking their structural properties into account. Individual CNTs and the 3D CNTs/G networks by means of an in-situ conductive atomic force microscope inside a scanning electron microscope are electrically characterized. Time-resolved photoluminescence demonstrated fast charge transfer and high carrier collection efficiency superior to two-dimensional ultrathin graphite only. Their facile and tunable growth and excellent electrical properties show that the 3D CNTs/G are strongly attractive for various applications such as solar cells, sensors, supercapacitors, photovoltaics, power generation, and optoelectronics. ispartof: SCIENTIFIC REPORTS vol:9 issue:1 ispartof: location:England status: published

Achieving perfect light absorption at a subwavelength-scale thickness has various advantageous in terms of cost, flexibility, weight, and performance for many different applications. However, obtaining perfect absorbers covering a wide range of wavelengths regardless of incident angle and input polarization without a complicated patterning process while maintaining a small thickness remains a challenge. In this paper, we demonstrate flat, lithography-free, ultrahigh omnidirectional, polarization-independent, broadband absorbers through effective dispersion engineering. The proposed absorbers show day-integrated solar energy absorption up to 96%, which is 32% better than with lossy semiconductor/metal absorbers. The proposed simple yet effective method can be applied to light absorption thin film structures based on various types of highly lossy semiconductor materials, including emerging 2D materials.

Electrospinning used to fabricate eco-friendly, transparent, human hair-based nanofibers (NFs) using natural resources such as keratin (which is found in hair, wool, feather, nails, and horns). These NF-based textiles are very useful in making transparent, wearable electronics, as they possess unique optical properties in the visible light regions, such as transparency exceeding 85%. The resulting environmentally friendly, hair-based NFs were investigated through various methods. In order to study transparent property of optically transparent NFs for applying transparent wearable devices, we fabricated transparent flexible consolidated sandwich structures embedded in NF textiles with polymer light-emitting diodes (PLEDs). The devices exhibit the fabrication process and characterization of consolidated textiles and PLEDs by using various color emission type of polymer. Also, we investigated a comparison between PLEDs without textiles and consolidated PLEDs with textile. When used white, red, and yellow polymer in this consolidated textile/LEDs/textile structures, the performances of device was obtained from a spectrally white, red, and yellow color light with a maximum luminance of 2781, 2430, and 6305 cd/m 2 at 13, 11, and 10 V, respectively. The LED characteristics of the consolidated PLEDs with textile maintained similar device efficiencies of PLEDs without textiles.

This work reports on the in-situ chemical synthesis and their properties of multilayer graphene (MLG) shells, made by unzipping single walled carbon nanotubes (SWCNTs), on the surface of Zinc oxide (ZnO) core nanoparticles (NPs). The stable oxygen bridge bonds between the ZnO core and the oxygen-related functional groups on the MLG shells facilitate the efficient photoinduced charge separation. This charge separation mechanism is confirmed experimentally using time-correlated single photon counting (TCSPC) measurements. The calculated average carrier lifetimes of the ZnO@MLG NPs are approximately 102 times faster than those for the bare ZnO NPs. The efficient electron transfer between the ZnO core and the MLG shell resulted in the significant improvement of the photocatalytic activity and the photoelectrochemical response. Simultaneously, the photocorrosion of ZnO was prevented by having the oxygen bridge bonds between the ZnO and MLG which suppressed the photo-generated holes oxidizing the surface oxygen atoms on ZnO, and in turn the holes are consumed by photocatalytic reaction. The 4.3 times enhanced photocurrent density at 0.2 V vs. Ag/AgCl (pH 6.9) and around 10 times higher rate constant value of photodegradation of rhodamine B were achieved by ZnO@MLG NPs in comparison with those of bare ZnO NPs.

We characterized alkali-activated slag paste containing dredged marine sediment according to Na2O concentration by mass of slag in the mixture. The compressive strengths of 3-d cured AAS–sediment paste specimens were similar to those of 28-d cured AAS–sediment paste specimens. The optimum Na2O concentration by mass of slag was 6–8%. Leaching testing of samples cured for 3 d confirmed that heavy metals (Cr, Cu, Cd, and Pb) were below the detection limits for all these metals. X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy analyses revealed that the microstructure, fracture surface, and silicate band of calcium silicate hydrate as the main hydrate of the AAS–sediment paste were similar among the various samples. Despite this, Ca/Si molar ratios and quantitative analysis results differed among samples with different Na2O concentrations by mass of slag.

Recently, interfacial engineering approaches as an efficient strategy for improving the power conversion efficiencies (PCEs) of inverted polymer solar cells (iPSCs) has attracted considerable attention. Among various efficient solutions, solution-processed metal-oxide films prepared from metal oxide sol–gel precursors (or nanoparticles) and polymer surface modifiers are typically used as electron selective interfaces in the inverted cell geometry. To present a more effective strategy for surpassing the limitations of traditional methods, such as an unintended increase in series or contact resistance by incompatibility at the organic/inorganic interface, inherently insulating nature of non-conjugated surface modifiers and oxygen adsorption (or photo-induced doping) of metal-oxide layer, we synthesize chemically surface-modified ZnO@graphene core–shell type quantum dots (ZGQDs) with well-characterization of the chemical, optical and electrical properties, and fabricate iPSCs consisting of ITO/PEIE/ZGQD-OAs/photoactive layer/MoO 3 /Ag. The mono-layered QDs play the multi-functional role as surface modifier, sub-photosensitizer and electron transport layer. Using this effective approach, we achieve the highest conversion efficiency of ~10.3% resulting from improved interfacial properties and efficient charge transfer based on static quenching and charge transfer reaction from ZnO to graphene nanosheets (with drastically reduced τ avg (~ 60 ps)), which is verified by various analysis tools.

The influence of the addition of waste glass, derived from spent fluorescent lamps, on the microstructure and strength of fly ash or fly ash/blast furnace slag-based inorganic polymers was studied through microstructural, spectroscopic, and compressive strength analyses. The results suggest that the degree of polymerization of the activated mixtures decreases as the amount of waste glass added to the synthesis mixtures increases. This finding is most likely due to the considerable increase in the overall SiO2/Al2O3 molar ratio. The strength followed the same trend. The addition of slag to the synthesis mixtures appears to be beneficial because the compressive strength was improved compared with other mixtures activated with the same sodium hydroxide solution but with no slag. The negative effect caused by increasing the overall SiO2/Al2O3 molar ratio through the addition of waste glass seems to be diminished when a sodium silicate solution is used as an activator.

The tungsten oxide nonvolatile memory devices were fabricated using the photothermal in-situ oxidation method. The photothermal in-situ oxidation method can monitor the oxidation process in real time. Raman spectra revealed that tungsten oxides were formed by thermal oxidation. The ON/OFF ratio of the current bistability for the device was as large as ~ 102 at a 2 V reading voltage, and the cycling endurance of the ON/OFF switching for the devices was stable without noticeable degradation. Memory mechanisms for device are described using fitted the I–V curves.

Hexagonal boron nitride (hBN) has drawn great attention for its versatile applications in electronics and photonics, and precise estimation of its thickness is critical in many situations. We propose a rapid and broad range (10–500 nm) in situ thickness estimation method for transparent hBN and SiO2 layers on the Si substrate using Raman peak intensity ratios at two wavenumbers and optical microscopy image analysis. We theoretically and experimentally demonstrate our method for a wide range of hBN layer thicknesses, and the estimated results show excellent agreement with the measured results with a percentile estimation error of 2.5%.

We demonstrate the ZnO@graphene core@shell quantum dot (ZGQDs) fabricated by selectively engineering of oxygenated functional groups on the graphene shells with eco-friendly keratin textile for transparent and flexible UV photodetector devices. The ZGQDs with the octylamine (ZGQDs-OA) and the graphene sheet were employed as an active material and an electron transport channel. The functional groups on the surrounding graphene shell in ZGQDs were passivated by the OA, resulting in a good absorbance in UV light and excellent carrier transport properties. The passivation of the functional groups on the graphene shell by OA drastically enhanced the photocurrent. Optical transmittance of the ZGQDs-OA/graphene sheets/PMMA/keratin nanofiber textile composites structures was approximately 77% at the visible spectrum range. Current–voltage (I-V) and current–time (I-t) measurements on the UV photodetector under illumination state in bending condition exhibited the excellent ON/OFF switching states and stability. The photosensitivity and responsivity of the photodetector with ZGQDs-OA were found to be around 13.10 and 68.64 μAmW−1, respectively, which is much higher than that without the passivation. The improved performance of the photodetector with ZGQDs-OA could be attributed to the efficient electron transport to the electrode by the passivation of the graphene on ZnO QDs.

Fine dredged sediment was immobilized using ground granulated blast furnace slag as a new binder for supplementary cementitious materials in a 3.5% NaOH solution to study its solidification/stabilization (S/S) and uses in various industrial applications. The aim of this study is to compare effect of mixing conditions of the saturated-surface-dry of dredged sediment to determine the proper mixing method in the S/S process. Measurements of mechanical strength, heavy metal leachability, and microstructural characterization of the dredged sediment treated with alkali-activated slag (AAS) paste were carried out. The maximum value of the mechanical strength was obtained when the same amount of the NaOH solution as the saturated-surface-dry of the dredged sediment was added. The leaching experiment results showed that heavy metals were immobilized in the AAS paste, and that Cr, Cd, and Pb were not detected. The results of the analysis indicate the relationship between mechanical strength and (Ca + Na)/(S...

In this study, a series of hot-melt pressure sensitive adhesives (HMPSAs) based on metallocene polyolefin (me-PO) were prepared to investigate their possibility of replacing the HMPSAs based on styrenic block copolymers (SBCs). In addition, to optimize the performance of HMPSAs based on me-PO, several tackifiers having different softening point and molecular weight were evaluated. To achieve the HMPSAs which can satisfy the Dahlquist Criterion, hot melts required over 10% of process oil. To obtain the HMPSAs having low viscosity which can be applied by a spraying type applicator, secondary polymer having relatively low crystallinity was required. And, tackifier having high molecular weight attributed to increasing the cohesive strength of me-PO based HMPSAs.

We discuss subwavelength-scale semiconductor metal-optic resonators placed on the metal substrate with various top metal plate sizes. Albeit with large optical losses, addition of metal layers converts a leaky semiconductor nano-block into a highly-confined optical cavity. Optically pumped lasing action is observed with the extended top metal layer that can significantly suppress the radiation losses. Careful investigation of self-heating effects during the optical carrier injection process shows the importance of temperature-dependent material properties in the laser rate equation model and the overall laser performances.

Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems.

Optical feedback mechanisms are often obtained from well-defined resonator structures fabricated by top-down processes. Here, we demonstrate that two-dimensional networks of metallic nanowires dispersed on the semiconductor slab can provide strong in-plane optical feedback and, thus, form randomly-distributed Fabry-Pérot-type resonators that can achieve multi- or single-mode lasing action in the near infrared wavelengths. Albeit with their subwavelength-scale cross-sections and uncontrolled inter-nanowire distances, a cluster of nearly parallel metal nanowires acts as an effective in-situ reflector for the semiconductor-metal slab waveguide modes for coherent optical feedback in the lateral direction. Fabry-Pérot type resonance can be readily developed by a pair of such clusters coincidentally formed in the solution-processed random nanowire network. Our low-cost and large-area approach for opportunistic random cavity formation would open a new pathway for integrated planar light sources for low-coherence imaging and sensing applications.

Organic bistable devices (OBDs) fabricated utilizing CuInS2 (CIS)/ZnS core–shell-type quantum dots (QDs) blended with a poly(N-vinylcarbazole) (PVK) layer were fabricated on polyethylene terephthalate (PET) substrates by using a spin-coating technique. Transmission electron microscopy images revealed that the CIS/ZnS QDs were distributed over the surface of the PVK layer. Current–voltage (I–V) curves for the Al/PVK + [CIS/ZnS QDs]/ITO/PET devices at 300 K showed that the maximum ON/OFF ratio of the current bistability for the OBDs was as large as 3.9 × 104. Memory mechanisms for the OBDs fabricated on PET substrates are described on the basis of the I–V results.

Organic bistable devices (OBDs) based on [6,6]-phenyl-C85 butyric acid methyl ester ([84]PCBM) embedded in a polymethyl methacrylate (PMMA) layer were fabricated by using a simple spin-coating technique. Atomic force microscope images showed that the surface roughness of the [84]PCBM:PMMA composite layer was uniform. Current density–voltage curves for the memory device showed a current bistability. The maximum ON/OFF ratio of the current bistability of the OBDs was as large as 10 3 . Write–read–erase–read characteristics showed OBDs with rewriteable nonvolatile memories, and the retention time of the OBDs was about 10 4 s. The ON state and the OFF state for 20 randomly-chosen cells demonstrated the high reproducibility of the fabricated OBDs.

The electrical properties of flexible nonvolatile organic bistable devices (OBDs) fabricated with graphene sandwiched between two insulating poly(methyl methacrylate) (PMMA) polymer layers were investigated. Current-voltage (I-V) measurements on the Al/PMMA/graphene/PMMA/indium-tin-oxide/poly(ethylene terephthalate) devices at 300 K showed a current bistability due to the existence of the graphene, indicative of charge storage in the graphene. The maximum ON/OFF ratio of the current bistability for the fabricated OBDs was as large as 1 x 10(7), and the endurance number of ON/OFF switchings was 1.5 x 10(5) cycles, and an ON/OFF ratio of 4.4 x 10(6) was maintained for retention times larger than 1 x 10(5) s. No interference effect was observed for the scaled-down OBDs containing a graphene layer. The memory characteristics of the OBDs maintained similar device efficiencies after bending and were stable during repetitive bendings of the OBDs. The mechanisms for these characteristics of the fabricated OBDs are described on the basis of the I-V results.

We present details of a 1×4 angled multimode interferometer (de)multiplexer, integrated with a microdisk laser as a demonstration of the way in which the compound semiconductor lasers can be coupled to silicon devices for a multitude of applications.

We discuss the rapid in situ hydrothermal synthesis of metal oxide materials based on the photothermal superheating of light-absorbing metal layers for simple and facile on-demand placement of semiconductor materials with micrometer-scale lateral resolution. Localized heating from pulsed and focused laser illumination enables ultrafast growth of metal oxide materials with high spatiotemporal precision in aqueous precursor solution. Among many possible electronic and optoelectronic applications, the proposed method can be used for laser-based in situ real-time soldering of separated metal structures and electrodes with functionalized semiconductor materials. Resistive electrical interconnections of metal strip lines as well as sensitive UV detection using photohydrothermally grown metal oxide bumps are experimentally demonstrated.

We demonstrate tungsten oxide semiconductor nanostructures fabricated by photothermal oxidation processes on the suspended metal nano-layer. The electrical conductivities of the nanobeam structures are measured against the temperature to validate their metal/semiconductor material properties.

We report room-temperature lasing from an optically pumped subwavelength-scale cylindrical InGaAsP pillar surrounded by circular Bragg reflectors on a metal substrate with a dielectric spacer layer. By taking advantage of wide in-plane photonic bandgaps and proper vertical antiresonances, three dielectric Bragg pairs produce a sufficient optical feedback capable of low threshold lasing from the fundamental TE011 mode. A large spontaneous emission coupling into the lasing mode is obtained from the cavity-enhanced Purcell effects and effective suppression of nonlasing modes.

We propose a modified nanopatch cavity with a cuboidal semiconductor sandwiched between extended metal planes. Experimental results show the quality factor of ~200 can be achieved with an effective mode volume of ~0.0064 cubic wavelength.

We report a photonic bandedge laser using subwavelength-scale pillars with a metal reflector plane bonded on the silicon substrate. Surface-emitting operation near the gamma point of the photonic band diagram is observed at 77 K.

We demonstrate room-temperature operation of a metallodielectric semiconductor laser with circular Bragg reflectors and a bottom metal plane. Experimental results show that the quality factor of ∼1300 and the effective threshold of 12 µW.

We report on the use of non-imaging reflectors to improve the collection efficiency of fluorescence detection systems. Half-sphere mirrors redirect the isotropic fluorescent emission toward the photodetector, and significantly enhance the fluorescence signal.

Bulk NiO is a well-known antiferromagnet with Neel temperature TN(∞) = 524 K and an optical band-gap Eg = 4.3 eV. With decrease in particle size D from 40 nm to 4 nm of NiO, systematic changes of TN and Eg are observed and discussed here. From magnetic measurements, the changes in TN with D are found to fit finite-size scaling equation TN(D) = TN(∞) [1 − (ξo/D)λ] with λ = 3.2 ± 0.5 and ξo = 3.2 ± 0.2 nm, in good agreement with the predictions for a Heisenberg system. The observed blue shifts of Eg with decrease in D reaching Eg = 5.12 eV for D ∼ 4 nm are likely due to quantum confinement and non-stoichiometry.

We present data, which were obtained before bending and after bending, for the electrical bistabilities, memory stabilities, and memory mechanisms of three-layer structured flexible bistable organic memory (BOM) devices, which were fabricated utilizing the ultrathin graphite sheets (UGS) sandwiched between insulating poly(methylmethacrylate) (PMMA) polymer layers. The UGS were formed by transferring UGS (about 30 layers) and using a simple spin-coating technique. Transmission electron microscopy (TEM) measurements were performed to investigate the microstructural properties of the PMMA/UGS/PMMA films. Current-voltage (I-V) measurements were carried out to investigate the electrical properties of the BOM devices containing the UGS embedded in the PMMA polymer. Current-time (I-t) and current-cycle measurements under flat and bent conditions were performed to investigate the memory stabilities of the BOM devices. The memory characteristics of the BOM maintained similar device efficiencies after bending and were stable during repeated bendings of the BOM devices. The mechanisms for these characteristics of the fabricated BOM are described on the basis of the I-V results.