Synthesis of Dicarboxylic Acids Comprising an Ether Linkage and Cyclic Skeleton and Its Further Application for High-Performance Aluminum Electrolyte Capacitors.

Aluminum electrolytic capacitors are essential components in all electronic devices, and it is known that their longevity depends on the performance of their electrolytes. We synthesized dicarboxylic acids having ether bonds showing the good solubility in ethylene glycol as a solvent and simultaneously developed a complete halogen removal method, which is strictly prohibited in capacitors. Moreover, the incorporation of bulky α-substituents and cyclic structures dramatically improved their heat resistance and can withstand high voltage, i.e., 764 V.

Enhanced Photovoltaic Performance of Inverted Perovskite Solar Cells through Surface Modification of a NiOx-Based Hole-Transporting Layer with Quaternary Ammonium Halide-Containing Cellulose Derivatives.

In this study, we positioned three quaternary ammonium halide-containing cellulose derivatives (PQF, PQCl, PQBr) as interfacial modification layers between the nickel oxide (NiOx) and methylammonium lead iodide (MAPbI3) layers of inverted perovskite solar cells (PVSCs). Inserting PQCl between the NiOx and MAPbI3 layers improved the interfacial contact, promoted the crystal growth, and passivated the interface and crystal defects, thereby resulting in MAPbI3 layers having larger crystal grains, better crystal quality, and lower surface roughness. Accordingly, the photovoltaic (PV) properties of PVSCs fabricated with PQCl-modified NiOx layers were improved when compared with those of the pristine sample. Furthermore, the PV properties of the PQCl-based PVSCs were much better than those of their PQF- and PQBr-based counterparts. A PVSC fabricated with PQCl-modified NiOx (fluorine-doped tin oxide/NiOx/PQCl-0.05/MAPbI3/PC61BM/bathocuproine/Ag) exhibited the best PV performance, with a photoconversion efficiency (PCE) of 14.40%, an open-circuit voltage of 1.06 V, a short-circuit current density of 18.35 mA/cm3, and a fill factor of 74.0%. Moreover, the PV parameters of the PVSC incorporating the PQCl-modified NiOx were further enhanced when blending MAPbI3 with PQCl. We obtained a PCE of 16.53% for this MAPbI3:PQCl-based PVSC. This PQCl-based PVSC retained 80% of its initial PCE after 900 h of storage under ambient conditions (30 °C; 60% relative humidity).

Citrate Functionalized Zirconium-Based Metal Organic Framework for the Fluorescent Detection of Ciprofloxacin in Aqueous Media.

Ciprofloxacin (CIP) is a commonly used antibiotic for the treatment of infectious diseases in humans and as a prophylactic agent in the livestock industry, leading to the environmental discharge of significant amounts of CIP. CIP is stable in aquatic systems leading to its pseudo-persistence. Constant exposure to these antibiotics results in the generation of antibiotic-resistant pathogens and potential toxicity/hypersensitivity in humans. Therefore, it is necessary to develop a convenient, rapid, and cost-effective method for the monitoring of ciprofloxacin in environmental samples. Rhodamine-based fluorescent receptors have the limitation of aqueous solubility. Therefore, in order to overcome this drawback, we designed a novel fluorescent receptor based on a zirconium-based metal organic framework (MOF-808). The precursor, MOF-808, was synthesized and functionalized by using sodium citrate to obtain a receptor called C-MOF-808. The C-MOF-808 was structurally characterized by XRD and spectroscopic analyses. Thus, this synthesized receptor can be used for the fluorescent detection of CIP in aqueous media with a detection limit of 9.4 µM. The detection phenomena of the receptor were studied by absorption as well as fluorescent spectra. The binding behavior of CIP with the receptor was studied by FT-IR and 1H-NMR analyses, and a binding mechanism is proposed.

Fabrication and Characterization of an Efficient Inverted Perovskite Solar Cells with POSS Passivating Hole Transport Layer.

Polyhedral oligomeric silsesquioxane (POSS), featuring a hollow-cage or semi-cage structure is a new type of organic-inorganic hybrid nanoparticles. POSS combines the advantages of inorganic components and organic components with a great potential for optoelectronic applications such as in emerging perovskite solar cells. When POSS is well dispersed in the polymer matrix, it can effectively improve the thermal, mechanical, magnetic, acoustic, and surface properties of the polymer. In this study, POSS was spin-coated as an ultra-thin passivation layer over the hole transporting layer of nickel-oxide (NOx) in the structure of a perovskite solar cell. The POSS incorporation led to a more hydrophobic and smoother surface for further perovskite deposition, resulting in the increase in the grain size of perovskite. An appropriate POSS passivation layer could effectively reduce the recombination of the electron and hole at grain boundaries and increase the short-circuit current from 18.0 to 20.5 mA·cm-2. Moreover, the open-circuit voltage of the cell could slightly increase over 1 V.

Enhanced Photovoltaic Properties of Perovskite Solar Cells by Employing Bathocuproine/Hydrophobic Polymer Films as Hole-Blocking/Electron-Transporting Interfacial Layers.

In this study, we improved the photovoltaic (PV) properties and storage stabilities of inverted perovskite solar cells (PVSCs) based on methylammonium lead iodide (MAPbI3) by employing bathocuproine (BCP)/poly(methyl methacrylate) (PMMA) and BCP/polyvinylpyrrolidone (PVP) as hole-blocking and electron-transporting interfacial layers. The architecture of the PVSCs was indium tin oxide/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate/MAPbI3/[6,6]-phenyl-C61-butyric acid methyl ester/BCP based interfacial layer/Ag. The presence of PMMA and PVP affected the morphological stability of the BCP and MAPbI3 layers. The storage-stability of the BCP/PMMA-based PVSCs was enhanced significantly relative to that of the corresponding unmodified BCP-based PVSC. Moreover, the PV performance of the BCP/PVP-based PVSCs was enhanced when compared with that of the unmodified BCP-based PVSC. Thus, incorporating hydrophobic polymers into BCP-based hole-blocking/electron-transporting interfacial layers can improve the PV performance and storage stability of PVSCs.

Effect of Polyethylene Glycol Incorporation in Electron Transport Layer on Photovoltaic Properties of Perovskite Solar Cells.

Due to the characteristics of high electron mobility, ambient stability, proper energy level, and low processing temperature, zinc oxide (ZnO) has become a very promising electron transport material for photovoltaics. However, perovskite solar cells fabricated with ZnO reveal low efficiency because perovskite crystals may decompose thermally on the surface of ZnO as a result of proton transfer reactions. In this study, we are the first to incorporate an inexpensive, non-toxic polyethylene glycol (PEG) into ZnO and explore the passivation effect on the electron transport layer of perovskite solar cells. Suspension stability, surface roughness, electrical conductivity, crystal size, and photovoltaic properties with respect to the PEG incorporation are analyzed. The experimental results revealed that PEG incorporation effectively passivated the surface defects of ZnO, increased the electrical conductivity, and suppressed the charge recombination. The photocurrent density could increase from 15.2 to 19.2 mA/cm2, an increase of 27%.

Enhanced Efficiencies of Perovskite Solar Cells by Incorporating Silver Nanowires into the Hole Transport Layer.

In this study, we incorporated silver nanowires (AgNWs) into poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a hole transport layer (HTL) for inverted perovskite solar cells (PVSCs). The effect of AgNW incorporation on the perovskite crystallization, charge transfer, and power conversion efficiency (PCE) of PVSCs were analyzed and discussed. Compared with neat PEDOT:PSS HTL, incorporation of few AgNWs into PEDOT:PSS can significantly enhance the PCE by 25%. However, the AgNW incorporation may result in performance overestimation due to the lateral charge transfer. The corrosion of AgNWs with a perovskite layer was discussed. Too much AgNW incorporation may lead to defects on the interface between the HTL and the perovskite layer. An extra PEDOT:PSS layer over the pristine PEDOT:PSS-AgNW layer can prevent AgNWs from corrosion by iodide ions.

MAPbI3 Incorporated with Carboxyl Group Chelated Titania for Planar Perovskite Solar Cells in Low-Temperature Process.

Low-temperature, solution-processed, highly efficient hybrid organic/inorganic perovskite planar heterojunction solar cells were fabricated by incorporating reactive crystalline titania (h-TAc) into MAPbI3 layers. The h-TAc was prepared by the sol-gel reaction at low temperature followed by solvothermal treatment. The photoelectrical properties of the solar cells with h-TAc were analyzed. The incorporation with 0.85-wt% h-TAc showed the highest power conversion efficiency (PCE, 15.9%), increasing 69% compared to the pristine cell. The enhancement arose from large-grained microstructures, leading to a low rate of charge recombination. The carboxyl groups chelated on the surface of h-TAc revealed a strong attraction to lead ions, which are significantly helpful to MAPbI3 crystal growth.

A star-shaped conjugated molecule featuring a triazole core and diketopyrrolopyrrole branches is an efficient electron-selective interlayer for inverted polymer solar cells.

A novel triazole-cored, star-shaped, conjugated molecule (TDGTPA) has been synthesized for use as an electron-selective interlayer in inverted polymer solar cells (PSCs). This star-shaped molecule comprised a triazole unit as the central core, 2,5-thienyl diketopyrrolopyrrole units as π-conjugated bridges, and tert-butyl-substituted triphenylamine units as both end groups and donor units. The inverted PSC had the device structure indium tin oxide/ZnO/TDGTPA/poly(3-hexylthiophene) (P3HT)/fullerene derivative (PC71BM)/MoO3/Ag. Inserting TDGTPA as the electron-selective layer enhanced the compatibility of the ZnO-based electron transport layer and the P3HT:PC71BM blend-based photoactive layer. The low energy of the lowest unoccupied molecular orbital (-3.98 eV) of TDGTPA was favorable for electron transfer from the photoactive layer to the ZnO layer, thereby enhancing the photovoltaic performance of the PSC. The photo-conversion efficiency of the device incorporating TDGTPA as the electron-selective layer was 15.8% greater than that of the corresponding device prepared without it.

Enhanced Optoelectronic Conversion Efficiency of CdSe/ZnS Quantum Dot/Graphene/Silver Nanowire Hybrid Thin Films.

In this study, we prepared the reduced graphene oxide (rGO)-CdSe/ZnS quantum dots (QDs) hybrid films on a three-layer scaffold that the QD layer was sandwiched between the two rGO layers. The photocurrent was induced by virtue of the facts that the rGO quenched the photoluminescence of QDs and transferred the excited energy. The quenching mechanism was attributed to the surface energy transfer, supported in our experimental results. We found that the optoelectronic conversion efficiency of the hybrid films can be significantly improved by incorporating the silver nanowires (AgNWs) into the QD layer. Upon increasing AgNW content, the photocurrent density increased from 22.1 to 80.3 µA cm(-2), reaching a near 3.6-fold enhancement compared to the pristine rGO-QD hybrid films. According to the analyses of photoluminescence spectra, shape effect, and electrochemical impedance spectra, the enhancement on the optoelectronic conversion efficiency arise mainly from the strong quenching ability of silver and the rapid electron transfer of AgNWs.

Effect of eccentricity on the electroosmotic flow in an elliptic channel.

The electroosmotic flow in an elliptic channel having constant surface potential (CSP) or charge density (CSCD) is considered at low potential and arbitrary double layer thickness. Analytical expressions for the flow velocity and the corresponding asymptotic results for thick double layers that are readily applicable to experimentalists are recovered. For the range of salt concentration usually encountered in practice, the mean flow velocity for the case of CSP differs both quantitatively and qualitatively from that for the case of CSCD. Using an equivalent circular channel to simulate an elliptic one is inappropriate, in general, neither is assuming electroneutrality on the channel axis even when double layer is ca. 1/3 of the equivalent channel radius.

Conductive polyurethane composites containing polyaniline-coated nano-silica.

In this study, we used 1.2-Aminopropyltriethoxysilane (APTS) as a coupling agent to synthesize silica-polyaniline (PANI) core-shell nanoparticles. The core-shell nanoparticles and PANI oligomers were reacted with isocyanates to prepare the conductive polyurethane (PU)-PANI-silica nanocomposites. The core-shell-nanoparticle structure shows significant enhancement on electrical properties of the conductive nanocomposites even though only 0.0755-wt.% PANI was coated on the nano-silica. The surface resistance of the nanocomposite containing 5 wt.% PANI can reduce to ~10(8) Ω/sq, lowering two orders in contrast to the nanocomposite without the core-shell structure. In comparison with the neat PU, tensile strength and elongation of the nanocomposite containing silica-PANI core-shell nanoparticles can increase 3.1 and 3.8 times, respectively. We suspect that the extraordinary enhancement of electrical and mechanical properties may result from the fact that contact probability among PANI moieties and chemical bonding between particles and PU matrix increase due to the PANI coated on the surface of silica.

Photonic bandgap of inverse opals prepared from core-shell spheres.

In this study, we synthesized monodispersed polystyrene (PS)-silica core-shell spheres with various shell thicknesses for the fabrication of photonic crystals. The shell thickness of the spheres was controlled by various additions of tetraethyl orthosilicate during the shell growth process. The shrinkage ratio of the inverse opal photonic crystals prepared from the core-shell spheres was significantly reduced from 14.7% to within 3%. We suspected that the improvement resulted from the confinement of silica shell to the contraction of PS space during calcination. Due to the shell effect, the inverse opals prepared from the core-shell spheres have higher filling fraction and larger wavelength of stop band maximum.

EDL configuration on a dissimilarly charged protrusion array via double Fourier series and perturbation method.

In this study, through the extension of an one-dimensional, dissimilarly charged protrusions surface model set up in our previous work, a novel dissimilarly charged protrusion array (DCPA) model immersed in an electrolyte solution, which could simulate realistically both the surface morphology and the surface charged condition profoundly concerned on a biological cell membrane, or on the surface of a micro-scale, modified particle used in biomedical engineering and water treatment, is proposed. Considering the condition of small protrusions, the electrical potential field due to the electrical double layer (EDL) on DCPA model is solved semi-analytically using both the double Fourier series and the perturbation method. The analysis from the numerical result reveals that, a small, dissimilarly charged protrusion can lead to a steep variation in the local EDL configuration, especially compared with that in the condition when the charged surface is taken roughly as a flat surface using a lumped, mean surface charge density.

Anti-scratch and transparency properties of transparent conductive carbon nanotube films improved by incorporating polyethoxysiloxane.

Transparent conductive films of single-walled carbon nanotubes (SWCNTs) were fabricated by a simple method to significantly enhance anti-scratch and transparency properties by the incorporation of polyethoxysiloxane (PES). The reasons for changes in the mechanical properties and transmittance were investigated through the reflection property and morphology of thin films. With the incorporation of PES, the sheet resistance of the SWCNT thin film remained unchanged after the anti-scratch test. It was found that the transmittance of the thin films suddenly increased when the thickness of the PES layer was ca 100 nm. Although the PES incorporation resulted in a slight increase in the sheet resistance, the experimental results revealed that the sheet resistance of the SWCNT thin films with PES was lower than that of films without PES for the same transmittance due to the increase of the transmittance caused by the PES incorporation. We have demonstrated that the sheet resistance was halved at a transmittance of ∼86% due to PES incorporation. SWCNT thin films with PES showed better electrical properties than those without PES after a bend test.

Solving EDL configuration near a dissimilarly charged protrusions surface model using perturbation method.

In this work, an elementary, novel dissimilarly charged protrusions (DCP) surface model in an electrolyte solution considering simultaneously the complexity of both surface morphology and surface charged condition, which are concerned frequently on a biological cell membrane, on a modified micro-particle surface, or in a lab-on-a-chip biosensor device, is proposed. Based on Fourier series and the perturbation technique, the configuration of electrical double layer (EDL) near this complicated charged surface model is successfully solved semi-analytically. The numerical calculation reveals that, the methodology suggested in present study could deal with charged surface systems of arbitrary geography and of arbitrary charge distribution. In the analysis, three special subjects are discussed, including an isolated dissimilarly charged protrusion, the effect of protrusions, and the effect of dissimilarly charged condition on protrusions.

A novel method to control inner and outer haze of an anti-glare film by surface modification of light-scattering particles.

Anti-glare films with various inner haze and outer haze were fabricated by a novel and simple method to modify the surface of the light-scattering particles via an acid or base treatment. The mechanism of formation of the inner and outer haze was investigated by the morphology of the AG coating layer. When the solvent evaporated, the treated light-scattering particles easily aggregated in the AG coating layer, increasing the outer haze and decreasing the inner haze. XPS analysis revealed that this result may have resulted from partial removal of the stabilizers on the light-scattering particles by the acid or base treatment. In this study, we demonstrated that the ratio of outer haze to inner haze varied from 0.32 to 3.14 with the same relative composition of particle, resin, and solvent in the AG coating; this ratio could be controlled by adjusting the proportion of untreated particles to treated particles.

Stability of soft colloidal particles in a salt-free medium.

The stability of a salt-free dispersion containing soft spherical colloidal particles is investigated theoretically. Here, a particle comprises a rigid core and an ion-penetrable membrane layer; the ionic species in the liquid phase come solely from those dissociated from the functional groups in the membrane layer. We show that, similar to the case of a salt-free rigid dispersion, the total energy, which comprises the electrical energy and the van der Waals energy, is always positive far away from the surface of a particle and does not have a secondary minimum. Both the Derjaguin approximation for the estimation the electrical energy of two spheres and the criteria for the critical coagulation concentration in the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory are inapplicable. If the molar concentration of the fixed charge in the membrane layer exceeds ca. 0.1 M, the stability of a dispersion remains roughly the same. The maximum allowable particle concentration for a stable dispersion for the case of soft particles is lower than that for the case of the corresponding rigid particles.

Analytic expressions for electrical energy and electrical force of two spheres.

Analytical expressions for the electrical force and the electrical energy of two spheres immersed in a symmetric electrolyte solution are derived under conditions of constant surface potential and constant surface charge. Previous analysis under Debye-Huckel condition (linear case) is extended to the corresponding nonlinear case; because the level of the surface potential is arbitrary the results obtained have much wider applications. In general, the performance of the analytical formulas derived is satisfactory, and better than that of the available results in literature. For the case of constant surface potential, the analytic formulas obtained are most accurate for large particles, and for the case of constant surface charge, they are most accurate for small particles.

The stability of a salt-free colloidal dispersion.

The electrical potential for the case of two identical, planar parallel particles immersed in a salt-free medium, where the ionic species in the counterions come solely from those that dissociated from the surfaces, is evaluated. Analytical expressions for the electrical potential, the concentration of counterions, and the electrical energy are derived. We show that in a salt-free dispersion, if the separation distance between two particles is sufficiently far, the electrical repulsive force dominates, that is, the total energy is positive and does not have a secondary minimum, which is not the case for a dispersion where both coions and counterions are present. Also, the conditions used to calculate the critical coagulation concentration in the classic Derjaguin-Landau-Verwey-Overbeek theory become inappropriate and the Derjaguin approximation is inapplicable. We show that if the surface charge density exceeds approximately 0.04 Cm(2), the stability of a salt-free dispersion remains essentially the same. If the surface charge density is sufficiently high, the maximum separation distance between two particles below which coagulation occurs is in the ranges of [0,1 nm] and [1,7 nm] for the cases where the Hamaker constant is 10(-20) and 10(-19) J, respectively.