Piezo inkjet formation of Ag nanoparticles from microdots arrays for surface plasmonic resonance.

The study aims to explore a novel approach for fabricating plasmonic nanostructures to enhance the optical properties and performance of various optoelectronic devices. The research begins by employing a piezo-inkjet printing technique to deposit drops containing Ag nanoparticles (NPs) onto a glass substrate at a predefined equidistance, with the goal of obtaining arrays of Ag microdots (Ag-µdots) on the glass substrate. This process is followed by a thermal annealing treatment. The printing parameters are first optimized to achieve uniform deposition of different sizes of Ag-µdots arrays by controlling the number of Ag ink drops. Subsequently, the printed arrays undergo thermal annealing at various temperatures in air for 60 min, enabling precise and uniform control over nanoparticle formation. The printed Ag nanoparticles are characterized using field emission scanning electron microscopy and atomic force microscopy to analyze their morphological features, ensuring their suitability for plasmonic applications. UV-Vis spectrophotometry is employed to investigate the enhanced surface-plasmonic-resonance properties of the printed AgNPs. Measurements confirm that the equidistant arrays of AgNPs obtained from annealing Ag microdots exhibit enhanced light-matter interaction, leading to a surface plasmon resonance response dependent on the Ag NPs' specific surface area. These enhanced surface plasmonic resonances open avenues for developing cutting-edge optoelectronic devices that leverage the benefits of plasmonic nanostructures, thereby enabling new opportunities for future technological developments across various fields.

Photonic Cooler Based on Multistacked Thin Films with Near-Infrared Filter Properties.

We report on the development of a multistacked configuration of a photonic cooler for implementation in sunny and arid regions. The optimized multistacking structure considers TiOx as a top layer, NiOx as the buffer layer, and Ag as a hot mirror (i.e., a reflective layer of the NIR light spectrum). The entire stacked layers were deposited in situ without breaking the vacuum. The oxide layers were grown reactively under an oxygen medium at a deposition pressure of 2 × 10-4 Torr. The level of TiOx surface wettability was demonstrated to be controlled by the oxygen flow during the film growth process, which may additionally provide a self-cleaning property to the IR filters. By combining low refractive index layers (i.e., TiOx) with the high refractive index of the metal oxides (i.e., NiOx) along with the metal layers (i.e., Ag, Al), the photonic filtration (i.e., cutoff) of the infrared spectrum was successfully achieved while keeping the light transmittance of the visible (vis) light above 50%. Different structures with different thicknesses have been systematically assessed, including TiOx/NiOx/Ag, TiOx/NiOx/Al, TiOx/MoOx/Ag, and TiOx/MoOx/Al. Furthermore, numerical simulations were carried out using SCAPS-1D and OptiLayer software to evaluate the application of these filters on silicon solar cells, considering the experimental electrical and optical parameters for each explicit layer of the device. Our results confirm that the development of such coatings with a scalable thin film growth process may have a real commercialization potential due to their multifunctionalities such as IR filtering, antireflection coating in the vis range, and antisoiling properties.

Bilobalide Induces Apoptosis in 3T3-L1 Mature Adipocytes through ROS-Mediated Mitochondria Pathway.

Bilobalide exhibits numerous beneficial bioactivities, including neuroprotective, anti-inflammatory, and antioxidant activity. Our previous study demonstrated that bilobalide inhibits adipogenesis and promotes lipolysis. The dose-dependent cytotoxicity was found to be specific to the mature adipocytes only, indicating the potential for regulating apoptosis in them. Herein, we aimed to investigate the apoptotic effects of bilobalide on 3T3-L1 mature adipocytes and elucidate the underlying mechanisms thereof. Flow cytometry analysis (FACS) revealed the pro-apoptotic effects of bilobalide on these cells. Bilobalide induced early apoptosis by reducing the mitochondrial membrane potential (MMP). DNA fragmentation was confirmed using TUNEL staining. Additionally, bilobalide increased the intracellular reactive oxygen species (ROS) levels and activities of Caspases 3/9. Pre-treatment with NAC (an ROS scavenger) confirmed the role of ROS in inducing apoptosis. Moreover, bilobalide up- and down-regulated the expression of Bax and Bcl-2, respectively, at the mRNA and protein expression levels; upregulated the Bax/Bcl-2 ratio; triggered the release of cytochrome c from the mitochondria; and increased the protein expression of cleaved Caspase 3, cleaved Caspase 9, and PARP cleavage. These results support the conclusion that bilobalide induces apoptosis in mature 3T3-L1 adipocytes through the ROS-mediated mitochondrial pathway, and offers potential novel treatment for obesity.

An additive manufacturing approach based on electrohydrodynamic printing to fabricate P3HT:PCBM thin films.

Additive manufacturing (AM) enables the production of high value and high performance components with applications from aerospace to biomedical fields. We report here on the fabrication of poly(3-hexylthiophene): phenyl-C61-butyric acid methyl ester (P3HT:PCBM) thin films through the electrohydrodynamic atomization (EHDA) process and its integration as absorber layer for organic solar cells. Prior to the film fabrication, the optimization of the process was carried out by developing the operating envelope for the P3HT:PCBM ink to determine the optimal flow rate and the appropriate applied voltage to achieve a stable-cone deposition mode. The EHDA printed thin-film's topography, morphology and optical properties were systematically analyzed. The root-mean-square roughness was found to vary significantly with the annealing temperature and the flow rate and ranged from 1.938 to 3.345 nm. The estimated film mass and thickness were found between 3.235 and 23.471 mg and 597.5 nm to 1.60 µm, respectively. The films exhibited a broad visible absorption spectrum ranging from ~ 340 to ~ 600 nm, with a maximum peak λmax located at ~ 500 nm. As the annealing temperature and the flow rate were increased, discernible alterations in the PCBM clusters were consequently observed in the blends of the film and the size of the PCBM clusters has decreased by 3% while the distance between them was highly reduced by as much as 82%.

Anti-Soiling Coatings for Enhancement of PV Panel Performance in Desert Environment: A Critical Review and Market Overview.

Areas with abundant sunlight, such as the Middle East and North Africa (MENA), are optimal for photovoltaic (PV) power generation. However, the average power loss of photovoltaic modules caused by dust accumulation is extreme and may reach 1%/day, necessitating frequent cleaning which adds to the cost of operations and maintenance. One of the solutions to the problem of PV soiling is to develop anti-soil coatings, where hydrophilic or hydrophobic coatings with spectral characteristics suitable for PV applications are added to the outer layer of PV glass. However, the effectiveness of such coatings depends extensively on climatic conditions and geographical locations. Since coatings add to the cost of solar panels, it is imperative that they are first tested for suitability at the intended location and/or in similar weather conditions prior to their large-scale deployment. This critical review focuses on various anti-dust technologies employed to mitigate the PV soiling issue. The in-depth comparison of the various developed techniques and materials aims at providing a relevant input in adapting the right technology based on particles' accumulation mechanism, weather conditions, and geographical location. Though the mechanical cleaning process is the most used solution to date, development of thin film anti-dust coating could be a better alternative-when it is relevant-due to its abrasion-free capability, large deployment, economic viability, and durability. This review aims at serving as a reference in this topic, thereby paving the way to adapting efficient anti-dust coatings, especially in the MENA region and/or desert environment at large, where it is the most relevant.

Laser ablation fabrication of ap-NiO/n-Si heterojunction for broadband and self-powered UV-Visible-NIR photodetection.

We report on the optoelectronic characteristics ofp-NiO/n-Si heterojunction photodiode for broadband photodetection, fabricated by depositing ap-type NiO thin film onto a commercialn-type silicon substrate using pulsed laser deposition (PLD) technique. The structural properties of the PLD-grownp-NiO material were analysed by means of x-ray diffraction and x-ray photoelectron spectroscopy, confirming its crystalline nature and revealing the presence of Ni vacancies, respectively. Hall measurements confirmed thep-type semiconducting nature of the NiO thin film having a carrier concentration of 8.4 × 1016cm-3. The current-voltage (I-V) characteristics of thep-NiO/n-Si heterojunction photodevice were investigated under different wavelengths ranging from UV to NIR. The self-bias properties under different illuminations of light were also explored systematically. Under self-bias condition, the photodiode exhibits excellent responsivities of 12.5 mA W-1, 24.6 mA W-1and 30.8 mA W-1with illumination under 365 nm, 485 nm, and 850 nm light, respectively. In addition, the time dependency of the photoresponse of the fabricated photodevice has also been investigated and discussed thoroughly.

Research Progress of Plasmonic Nanostructure-Enhanced Photovoltaic Solar Cells.

Enhancement of the electromagnetic properties of metallic nanostructures constitute an extensive research field related to plasmonics. The latter term is derived from plasmons, which are quanta corresponding to longitudinal waves that are propagating in matter by the collective motion of electrons. Plasmonics are increasingly finding wide application in sensing, microscopy, optical communications, biophotonics, and light trapping enhancement for solar energy conversion. Although the plasmonics field has relatively a short history of development, it has led to substantial advancement in enhancing the absorption of the solar spectrum and charge carrier separation efficiency. Recently, huge developments have been made in understanding the basic parameters and mechanisms governing the application of plasmonics, including the effects of nanoparticles' size, arrangement, and geometry and how all these factors impact the dielectric field in the surrounding medium of the plasmons. This review article emphasizes recent developments, fundamentals, and fabrication techniques for plasmonic nanostructures while investigating their thermal effects and detailing light-trapping enhancement mechanisms. The mismatch effect of the front and back light grating for optimum light trapping is also discussed. Different arrangements of plasmonic nanostructures in photovoltaics for efficiency enhancement, plasmonics' limitations, and modeling performance are also deeply explored.

Metamaterials and Metasurfaces: A Review from the Perspectives of Materials, Mechanisms and Advanced Metadevices.

Throughout human history, the control of light, electricity and heat has evolved to become the cornerstone of various innovations and developments in electrical and electromagnetic technologies. Wireless communications, laser and computer technologies have all been achieved by altering the way light and other energy forms act naturally and how to manage them in a controlled manner. At the nanoscale, to control light and heat, matured nanostructure fabrication techniques have been developed in the last two decades, and a wide range of groundbreaking processes have been achieved. Photonic crystals, nanolithography, plasmonics phenomena and nanoparticle manipulation are the main areas where these techniques have been applied successfully and led to an emergent material sciences branch known as metamaterials. Metamaterials and functional material development strategies are focused on the structures of the matter itself, which has led to unconventional and unique electromagnetic properties through the manipulation of light-and in a more general picture the electromagnetic waves-in widespread manner. Metamaterial's nanostructures have precise shape, geometry, size, direction and arrangement. Such configurations are impacting the electromagnetic light waves to generate novel properties that are difficult or even impossible to obtain with natural materials. This review discusses these metamaterials and metasurfaces from the perspectives of materials, mechanisms and advanced metadevices in depth, with the aim to serve as a solid reference for future works in this exciting and rapidly emerging topic.

High Performance of Anion Exchange Blend Membranes Based on Novel Phosphonium Cation Polymers for All-Vanadium Redox Flow Battery Applications.

The deployment of alkaline anion exchange membranes (AEMs) in flow battery applications has the advantage of a low cationic species crossover rate. However, the alkaline stability conjugated to the low conductivity of hydroxide ions of anion exchange membranes (AEMs) still represents a major drawback for the large deployment of such technology. In this study, three types of tetraarylpolyphosphonium (pTAP)-based copolymers (namely, CP1, CP2, and CP3) are synthesized and blended with chitosan and polyvinylidene fluoride (PVDF) for the fabrication of AEMs. Chitosan, a green biopolymer, was employed as a blend to enhance the water uptake of the base ionomer matrix. It is proposed that the abundancy of hydroxyl groups in chitosan improves considerably the ionic conductivity, water transport, and ion selectivity of the membrane, together with facilitating the dispersion of the chitosan in the pTAP copolymer matrix. The purpose of blending PVDF is instead to provide stable mechanical strength to the composite blend. The chemical, mechanical, and thermal stabilities of the three fabricated composite-blend membranes (i.e., CM1, CM2, and CM3) were characterized. All the membranes exhibited a high water retaining capacity of up to 36.26% (recorded for CM2) along with a hydroxyl ion conductivity of 17.39 mS cm-1. Due to the strong interactions between pTAP copolymers, chitosan, and PVDF polymers (confirmed also by Fourier transform infrared spectroscopy), the studied anion exchange membranes are able to retain up to 97% of the original OH conductivity after 1 M KOH treatment at room temperature for 100 h. The three membranes, namely, CM1, CM2, and CM3, have vanadium ion permeabilities measured at 20 °C of 1.775 × 10-8, 1.718 × 10-8, and 1.648 × 10-8 cm2/s, respectively, which are lower than that for the commercially available Nafion. The good stability and remarkable cell performance of the composite-blend membranes reported here make them definitely excellent candidates for the future generation of vanadium redox flow batteries.

Investigating the suitability of poly tetraarylphosphonium based anion exchange membranes for electrochemical applications.

Anion exchange membranes (AEMs) are becoming increasingly common in electrochemical energy conversion and storage systems around the world (EES). Proton-/cation-exchange membranes (which conduct positive charged ions such as H+ or Na+) have historically been used in many devices such as fuel cells, electrolysers, and redox flow batteries. High capital costs and the use of noble metal catalysts are two of the current major disadvantages of polymer electrolyte membrane (PEM)-based systems. AEMs may be able to overcome the limitations of conventional PEMs. As a result, polymers with anion exchange properties have recently attracted a lot of attention due to their significant benefits in terms of transitioning from a highly acidic to an alkaline environment, high kinetics for oxygen reduction and fuel oxidation in an alkaline environment, and lower cost due to the use of non-precious metals. The aim of this research was to learn more about the development of a new AEM based on poly tetraarylphosphonium ionomers (pTAP), which has high ionic conductivity, alkaline stability, thermal stability, and good mechanical properties, making it a more cost-effective and stable alternative to conventional and commercial AEMs. A simple solution casting method was used to build novel anion exchange composite membranes with controlled thicknesses using the synthesized pTAP with polysulfone (PS). To ensure their suitability for use as an electrolyte in alkaline electrochemical systems, the composite membranes were characterized using FTIR, XRD, water uptake, ionic conductivity, and alkaline stability. At 40 °C, the PS/pTAP 40/60 percent membrane had a maximum ionic conductivity of 4.2 mS/cm. The thermal and mechanical stability of the composite membranes were also examined, with no substantial weight loss observed up to 150 °C. These findings pave the way for these membranes to be used in a wide variety of electrochemical applications.

Synthesis and Characterization of a Novel Hydroquinone Sulfonate-Based Redox Active Ionic Liquid.

Introducing redox-active moieties into an ionic liquid (IL) structure is an exciting and attractive approach that has received increasing interest over recent years for a various range of energy applications. The so-called redox-active ionic liquids (RAILs) provide a highly versatile platform to potentially create multifunctional electroactive materials. Ionic liquids are molten salts consisting of ionic species, often having a melting point lower than 100 °C. Such liquids are obtained by combining a bulky asymmetric organic cation and a small anion. Here, we report on the synthesis of a novel RAIL, namely 1-butyl-3-methylimidazolium hydroquinone sulfonate ((BMIM)(HQS)). (BMIM)(HQS) was synthesized in a two-step procedure, starting by the quaternization of methylimidazole using butylchloride to produce 1-butyl-3-methylimidazolium chloride ((BMIM)(Cl)), and followed by the anion exchange reaction, where the chloride anion is exchanged with hydroquinone sulfonate. The resulting product was characterized by 1H NMR, 13C NMR, FT-IR spectroscopy, themogravimetric analysis, and differential scanning calorimetry, and shows a high stability up to 340 °C. Its electrochemical behavior was investigated using cyclic voltammetry at different temperatures and its viscosity analysis was also performed at variable temperatures. The electrochemical response of the presented RAIL was found to be temperature dependent and diffusion controlled. Overall, our results demonstrated that (BMIM)(mix of HQS and HSQ) is redox active and possesses high stability and low volatility, leading to the employment of this RAIL without any additional supporting electrolyte or additives.

Hydrophilic Antireflection and Antidust Silica Coatings.

We report on the optical and morphological properties of silica thin layers deposited by reactive RF magnetron sputtering of a SiO2 target under different oxygen to total flow ratios [r(O2) = O2/Ar, ranging from 0 to 25%]. The refractive index (n), extinction coefficient, total transmission, and total reflectance were systematically investigated, while field-emission scanning electron microscopy, atomic force microscopy, and three-dimensional (3D) average roughness data construction measurements were carried out to probe the surface morphology. Contact angle measurements were performed to assess the hydrophilicity of our coatings as a function of the oxygen content. We performed a thorough numerical analysis using 1D-solar cell capacitance simulator (SCAPS-1D) based on the measured experimental optical properties to simulate the photovoltaic (PV) device performance, where a clear improvement in the photoconversion efficiency from 25 to 26.5% was clearly observed with respect to r(O2). Finally, a computational analysis using OptiLayer confirmed a minimum total reflectance of less than 0.4% by coupling a silica layer with n = 1.415 with another high-refractive-index (i.e., >2) oxide layer. These promising results pave the way for optimization of silica thin films as efficient antireflection and self-cleaning coatings to display better PV performance in a variety of locations including a desert environment.

Single crystal structure, vibrational spectroscopy, gas sorption and antimicrobial properties of a new inorganic acidic diphosphates material (NH4)2Mg(H2P2O7)2•2H2O.

We report on the successful synthesis of diammonium magnesium dihydrogendiphosphate (V) dihydrate compound (NH4)2Mg(H2P2O7)2•2H2O using a wet chemical route. Single crystal X-ray diffraction analysis and micro Raman spectroscopy are employed to characterize the compound. We demonstrate, using a multidisciplinary approach, that this compound is ideal for carbon dioxide (CO2) capture in addition to other anthropogenic gasses. We show here -from both an experimental as well as from a density functional theory (DFT) calculations routes- the potential for adopting this compound into domestic air-conditioning units (ACUs). From these experiments, the resistance to bacterial growth is also investigated, which is critical for the adoption of this compound in ACUs. Our  compound exhibits a higher methane (CH4) sorptivity as compared to CO2 at 25 °C and 45 °C under pressures up to 50 bars. Furthermore, DFT electronic structure calculations are used to compute the main structural and electronic properties of the compound, taking into consideration the characteristics of the identified pores as a function of the progressive CO2 vs. CH4 loadings. Finally, the antibacterial assay reveals a strong antibacterial activity against the tested Gram-positive and Gram-negative bacteria, with a large zone of inhibition against the tested E. Coli, S. Aureus and K. Pneumonia.

Recovery of electro-mechanical properties inside self-healing composites through microencapsulation of carbon nanotubes.

We report the successful microencapsulation of multi-walled carbon nanotubes suspended in a 5-ethylidene-2-norbornene (5E2N) self-healing monomer, into poly melamine urea formaldehyde shells through in situ polymerization. The average size of the microcapsules, their size-distribution, shell wall structural integrity and thickness are  characterized by optical and scanning electron microscopy. The presence of carbon nanotubes (CNTs) inside the core liquid content, as well as their release after breaking is confirmed by microscopy and spectroscopy analyses. A small amount of CNTs inside the microcapsules is found to have no significant impact on the thermal stability of the system, as determined by thermogravimetric analysis and differential scanning calorimetry. Both the mechanical and the electrical properties of CNT-based self-healing materials can be restored  up to 80% when CNT/5E2N microcapsules are incorporated into polymer composites, thus making them highly suitable for applications in aerospace.

Effect of Synthesis on Performance of MXene/Iron Oxide Anode Material for Lithium-Ion Batteries.

Two-dimensional heterostructures, such as Fe2O3/MXene nanoparticles, can be attractive anode materials for lithium-ion batteries (LIBs) due to the synergy between high lithium-storage capacity of Fe2O3 and stable cyclability and high conductivity provided by MXene. Here, we improved the storage performance of Ti3C2T x (MXene)/Fe2O3 nanocomposite by confining Fe2O3 nanoparticles into Ti3C2T x nanosheets with different mixing ratios using a facile and scalable dry ball-milling process. Composites of Ti3C2T x-25 wt % Fe2O3 and Ti3C2T x-50 wt % Fe2O3 synthesized by ball-milling resulted in uniform distribution of Fe2O3 nanoparticles on Ti3C2T x nanosheets with minimum oxidation of MXene as compared to composites prepared by hydrothermal or wet sonication. Moreover, the composites demonstrated minimum restacking of the nanosheets and higher specific surface area. Among all studied composites, the Ti3C2T x-50 wt % Fe2O3 showed the highest reversible specific capacity of ∼270 mAh g-1 at 1C (∼203 mAh g-1 based on the composite) and rate performance of 100 mAh g-1 at 10C. This can open the door for synthesizing stable and high-performance MXene/transition metal oxide composites with significantly enhanced electrochemical performance for LIB applications.

Graphene nanoplatelet doping of P3HT:PCBM photoactive layer of bulk heterojunction organic solar cells for enhancing performance.

Hybrid organic photovoltaic (OPV) cells based on conjugated polymer photoactive materials are promising candidates for flexible, high-performance and low-cost energy sources owing to their inexpensive materials, cost-effective processing and ease of fabrication by simple solution processes. However, the modest PV performance obtained to date-in particular the low power conversion efficiency (PCE)-has impeded the large scale deployment of OPV cells. The low PCE in OPV solar cells is mainly attributed to the low carrier mobility, which is closely correlated to the transport diffusion length of the charge carriers within the photoactive layers. The 2D graphene material could be an excellent candidate for assisting charge transport improvement in the active layer of OPV cells, due to its huge carrier mobility, thermal and chemical stability, and its compatibility with the solution process. In this work, we report on the improvement of the optoelectronic properties and photovoltaic performance of graphene nanoplatelet (GNP)-doped P3HT:PCBM photoactive blended layers, integrated into a bulk heterojunction (BHJ) organic-photovoltaic-based device, using PEDOT:PSS on an ITO/glass substrate. First, the light absorption capacity was observed to increase with respect to the GNP content, while the photoluminescence showed clear quenching, indicating electron transfer between the graphene sheets and the polymeric matrix. Then, the incorporation of GNP into the BHJ active layer resulted in enhanced PV performance with respect to the reference cell, and the best PV performance was obtained with 3 wt.% of GNP loading, with an open-circuit voltage of 1.24 V, a short-circuit current density value of 6.18 mA cm-2, a fill factor of 47.12%, and a power conversion efficiency of about 3.61%. We believe that the obtained results contribute to the development of organic photovoltaic devices and to the understanding of the impact of sp2-bonded carbon therein.

Improved Self-cleaning Properties of an Efficient and Easy to Scale up TiO2 Thin Films Prepared by Adsorptive Self-Assembly.

Transparent titania coatings have self-cleaning and anti-reflection properties (AR) that are of great importance to minimize soiling effect on photovoltaic modules. In this work, TiO2 nanocolloids prepared by polyol reduction method were successfully used as coating thin films onto borosilicate glass substrates via adsorptive self-assembly process. The nanocolloids were characterized by transmission electron microscopy and x-ray diffraction. The average particle size was around 2.6 nm. The films which have an average thickness of 76.2 nm and refractive index of 1.51 showed distinctive anti soiling properties under desert environment. The film surface topography, uniformity, wettability, thickness and refractive index were characterized using x-ray diffraction, atomic force microscopy, scanning electron microscopy, water contact angle measurements and ellipsometry. The self-cleaning properties were investigated by optical microscopy and UV-Vis spectroscopy. The optical images show 56% reduction of dust deposition rate over the coated surfaces compared with bare glass substrates after 7 days of soiling. The transmission optical spectra of these films collected at normal incidence angle show high anti-reflection properties with the coated substrates having transmission loss of less than 6% compared to bare clean glass.

Structural and physical properties of the dust particles in Qatar and their influence on the PV panel performance.

Recently, extensive R&D has been conducted, both by industry and academia, to significantly raise the conversion efficiency of commercial photovoltaic (PV) modules. The installation of PV systems aimed at optimizing solar energy yield is primarily dictated by its geographic location and installation design to maximize solar exposure. However, even when these characteristics have been addressed appropriately, there are other factors that adversely affect the performance of PV systems, namely the temperature-induced voltage decrease leading to a PV power loss, and the dust accumulation (soiling). The latter is the lesser acknowledged factor that significantly influences the performance of PV installations especially in the Middle East region. In this paper we report on the investigation of the structural and physical properties of the desert-dust particles in the State of Qatar. The dust particles were collected directly from the PV panels installed in desert environment and characterized by different techniques, including scanning electron, optical and atomic force microscopies, X-ray diffraction, energy-dispersive, UV-Vis, micro-Raman and Fourier transform infrared spectroscopy. The vibrating sample magnetometry analyses were also conducted to study the magnetic properties of the dust particles. The influence of the dust accumulation on the PV panel performance was also presented and discussed.