Synthesis of Al and Ag nanoparticles through ultra-sonic dissociation of thermal evaporation deposited thin films for promising clinical applications as polymer nanocomposite

Nanoparticles (NPs) having well-defined shape, size and clean surface serve as ideal model system to investigate surface/interfacial reactions. Ag and Al NPs are receiving great interest due to their wide applications in bio-medical field, aerospace and space technology as combustible additives in propellants and hydrogen generation. Hence, in this study, we have synthesized Ag and Al NPs using an innovative approach of ultra-sonic dissociation of thin films. Phase and particle size distributions of the Ag and Al NPs have been determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thin film dissociation/dissolution mechanism, hence conversion into NPs has been characterized by SEM- scanning electron microscope. EDXA & ICPMS have been performed for chemical analysis of NPs. Optical properties have been characterized by UV-Vis and PL spectroscopy. These NPs have also been investigated for their anti-bacterial activity against Escherichia coli bacteria. To the best of our knowledge, this is the first time when NPs has been synthesized by ultra-sonic dissociation of thin films. As an application, these NPs were used further for synthesis of nanocomposite polymer membranes, which show excellent activity against bio film formation

New emerging rare-earth free yellow emitting 2D BCNO nanophosphor for white light emitting diodes

We have demonstrated a new emerging rare-earth free highly-efficient two dimensional (2D) boron carbon oxynitride (BCNO) yellow emitting nanophosphor with high quantum efficiency for white light emitting diode (WLED) devices. This BCNO nanophosphor exhibits 2D layered structures analogous to hexagonal BN phase. Further, the EELS and XPS results confirm the nanophosphor consisted of B, C, N and O elements. The BCNO nanophosphor shows a broad highly intense yellow emission band centered at 580 nm corresponding to 470 nm excitation wavelength with a quantum efficiency approaching 89%. This novel nanophosphor with strong emission has subsequently been integrated to chip on board (CoB) based blue LEDs in order to fabricate WLEDs devices with a color rendering index of 92. Low color temperature (4899) and better CIE color coordinates (x = 0.3496, y = 0.3679) of a fabricated WLEDs device supports a 2D BCNO nanophosphor that could be an exceptional choice for CoB based WLEDs. Hence, our method provides a facile synthesis of rare-earth free 2D lightweight BCNO nanophosphor and its integration with CoB based blue LEDs for next generation advanced solid state white light applications

An n-type, new emerging luminescent polybenzodioxane polymer for application in solution-processed green emitting OLEDs

Herein, we report polybenzodioxane polymer (PIM-1), a multifunctional n-type emitter with strong green luminescence, and its suitability as an electron transport layer for OLEDs devices. The Brunauer-Emmett- Teller (BET) test and photo-electrical properties of as-synthesized PIM-1 confirm the presence of large microporosity and excellent electron mobility. The photoluminescence (PL) spectroscopy shows the intense green emission at 515 nm upon 332 nm excitation wavelength. Moreover, the Hall effect study reveals the negative Hall resistivity, which indicates that PIM-1 possesses n-type semiconductor characteristics. It enables the highly-efficient polymer-based green LEDs with configuration; ITO (120 nm)/PEDOT: PSS (30 nm)/PIM-1 (100 nm)/LiF (1 nm)/Al (150 nm), which are fabricated by the sequential solution-processing method. The OLED incorporating PIM-1 thin layer achieves maximum current efficiency of 1.71 Cd A(-1) and power efficiency of 0.49 lm W-1. Additionally, the electron mobility is found to be 4.4 x 10(-6) cm(2) V-1 s(-1). Hence, these results demonstrate that PIM-1 could be an ultimate choice as an n-type emitter for the next generation of advanced electronic devices

New Insights into the Triton X-100 Induced Chemical Exfoliation of MoS2 to Derive Highly Luminescent Nanosheets

The exfoliation of two dimensional (2D) transition metal dichalcogenides (TMDs) into mono- or few-layers without compromising their semiconductor properties has momentous interest for both point of view; fundamental studies and further implementation in practical applications. Herein, we reported a novel and inexpensive approach for high yield nanosheets from bulk MoS2 to few layers of strong luminescent MoS2 nanosheets using Triton X-100 as a surfactant with tailoring the bulk band gap 1.2 eV to 1.79 eV of few layers of nanosheets after chemical exfoliation process, which can be easily scaled-up in large quantity. The microstructural results reveal that the exfoliated nanosheets have thickness in the range of few layers and lateral dimension in the range of few hundred nanometers. Our findings may offer a new innovative one setup chemical exfoliation process to design a few layer of MoS2 nanosheets without suppressing luminescent properties, which is highly desirable for the next generation optoelectronic devices

Probing on green long persistent Eu2+/Dy3+ doped Sr3SiAl4O11 emerging phosphor for security applications

Herein, a novel green emitting long-persistent Sr(3)SiAl(4)O(1)1:Eu2+/Dy3+ phosphor was synthesized in a single phase form using facile solid state reaction method under the reducing atmosphere of 10% H-2 and 90% N-2. The resulting phosphor exhibits hyper-sensitive strong broad green emission, peaking at 510 nm upon 340 nm excitation wavelength, which is attributed to the 4f(6)5d(1)-4f(7) transitions of emission center of europium (Eu2+) ions. Moreover, the incorporation of dysprosium (Dy3+) ions, which act as effective hole trap centers with appropriate depth, largely enhances the photoluminescence characteristics and greatly improves the persistent intense luminescence behavior of Sr3SiAl4O11:Eu2+/Dy3+ phosphor under ultraviolet (UV) excitation. In addition, with the optimum doping concentration and sufficient UV excitation time period, the as-synthesized phosphor can be persisted afterglow for time duration similar to 4 h with maximum luminescence intensity. Thus, these results suggest that this phosphor could be expected as an ultimate choice for next generation advanced luminescent materials in security applications such as latent finger-marks detection, photo-masking induced phosphorescent images, and security code detection

Luminomagnetic bifunctionality of Mn2+-bonded graphene oxide/reduced graphene oxide two dimensional nanosheets

Herein, we report the luminomagnetic bifunctional properties of two-dimensional (2D) Mn2+ bonded graphene oxide (GO)/reduced graphene oxide (RGO) nanosheets synthesized using a facile route of oxidation followed by a solvothermal reduction method. Photoluminescence (PL) studies (excited by different wavelengths) revealed that the resonant energy transfer between Mn2+ and sp(3)/sp(2) clusters of GO/RGO is responsible for the enhancement of emissions. Moreover, pH-sensitive PL behaviors have also been investigated in detail. The ferromagnetic behavior is believed to arise due to defects in Mn2+ bonded GO composites. Thus, present reduction method provides a direct route to tune and enhance the optical properties of GO and RGO nanosheets bonded with Mn2+ ions, which creates an opportunity for various technological applications

High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures

The vertical aligned carbon nanotubes (CNTs)-based pillar architectures were created on laminated silicon oxide/silicon (SiO2/Si) wafer substrate at 775 degrees C by using water-assisted chemical vapor deposition under low pressure process condition. The lamination was carried out by aluminum (Al, 10.0 nm thickness) as a barrier layer and iron (Fe, 1.5 nm thickness) as a catalyst precursor layer sequentially on a silicon wafer substrate. Scanning electron microscope (SEM) images show that synthesized CNTs are vertically aligned and uniformly distributed with a high density. The CNTs have approximately 2-30 walls with an inner diameter of 3-8 nm. Raman spectrum analysis shows G-band at 1580 cm(-1) and D-band at 1340 cm(-1). The G-band is higher than D-band, which indicates that CNTs are highly graphitized. The field emission analysis of the CNTs revealed high field emission current density (4mA/cm(2) at 1.2V/mu m), low turn-on field (0.6 V/mu m) and field enhancement factor (6917) with better stability and longer lifetime. Emitter morphology resulting in improved promising field emission performances, which is a crucial factor for the fabrication of pillared shaped vertical aligned CNTs bundles as practical electron source

A novel strategy to enhance ultraviolet light driven photocatalysis from graphene quantum dots infilled TiO2 nanotube arrays

Herein, a novel strategy has been proposed to fabricate graphene quantum dots (GQDs) infilled titanium dioxide (TiO2) nanotube arrays (NTAs) hybrid structure for dye degradation of methylene blue (MB) under UV light (365 nm) irradiation. GQDs are infilled inside the TiO2 NTAs (via anodic oxidation of a Ti sheet) through an impregnation method. Moreover, the morphology of the TiO2 NTAs is well maintained after filling the GQDs inside, which is favorable for mass transfer. The peak intensity of photoluminescence (PL) spectra of the GQDs infilled TiO2 NTAs catalyst is lower than that of annealed TiO2 NTAs and a strong violet UV emission is obtained at 387 nm upon 252 nm deep UV excitation. The photocatalytic activities of the TiO2 NTAs are evaluated in terms of the efficiencies of photo-decomposition and adsorption of MB in aqueous solution under UV light irradiation, after the impregnation of GQDs inside the TiO2 NTAs. The highly-efficient photocatalytic activity is attributed to the broad absorption in the visible wavelength region, large photo-induced charge separation through the transfer of photo-generated electrons from the TiO2 NTAs to GQDs, as well as the strong adsorption capacity of the GQDs to MB molecules. Thus, the GQDs infilled TiO2 NTAs could be widely used as a photocatalyst for treating organic contaminants in the field of environmental protection

Sunlight-activated Eu2+/Dy3+ doped SrAl2O4 water resistant phosphorescent layer for optical displays and defence applications

Herein, we introduce a strategy for the fabrication of a sunlight-activated green luminescent Eu2+/Dy3+ doped strontium aluminate (Sr1 12x 12yAl2O4:Eux2+/Dyy3+) assisted long persistent, transparent, flexible and water resistant phosphorescent layer via a customized solid state reaction-solution casting method. The XRD result of as-synthesized phosphor shows a pure monoclinic crystal structure with the space group P21. This as-synthesized phosphor exhibits green afterglow emission with a broad band peaking 3c528 nm upon a broad range of excitation wavelengths from 368\u2013418 nm, which is ascribed to the characteristic 4f65d1 \u2192 4f7 electronic dipole allowed transition of Eu2+ ions. Moreover, the role of Dy3+ as an auxiliary activator significantly prolongs the afterglow duration to a large extent by increasing the number of electron traps and their trap depths in the vicinity of Eu2+. Accordingly, a brighter afterglow intensity with a time more than 5 hours is observed for the optimal concentration of Eu2+/Dy3+ in Sr1 12x 12yAl2O4:Eux2+/Dyy3+, (x = 0.1 and y = 0.2) in the long persistent phosphor. The incorporation of the sunlight-activated as-synthesized Sr0.7Al2O4:Eu0.12+/Dy0.23+ phosphor in a commercially available PVC gold medium offers a highly dispersive transparent luminescent paint, which can be used for the spray coating of monuments, as well as for the fabrication of transparent, flexible and water resistant phosphorescent layers. Hence, these striking features of the luminescent paint, as well as the flexible transparent phosphorescent layer could be potentially utilized in optical displays and defence applications

Fabrication of highly efficient resonant structure assisted ultrathin artificially stacked Ag/ZnS/Ag multilayer films for color filter applications

We introduce a novel strategy for the fabrication of mechanically and thermally stable highly efficient resonant structure assisted ultrathin artificially stacked Ag/ZnS/Ag multilayer films on cleaned glass substrates using the thermal evaporation technique. The application of fabricated color filters has been studied in the visible range. These multilayers have good adhesion to each other and to the glass substrate, resulting in mechanical and thermal stability. The stability has been examined by the "Scotch-tape'' test and the ultrasonication process at 37 kHz frequency and at 40 degrees C temperature as well as by thermogravimetric analysis (TGA). The results of the structural analysis, surface morphology and atomic force microscopy of these filters confirm the good crystallinity with a low value of surface roughness. The effect of thickness of artificially stacked metal (Ag) and dielectric (ZnS) layers has been examined in terms of optical properties by several spectroscopic techniques. These ingenious filters exhibit a large and deep stop band in the visible wavelength region. Thus blue, green and red color filters, centered at 460, 540 and 620 nm having bandwidths of about 25, 44 and 35 nm, respectively, were achieved. Moreover, the statistical outcomes of all the three filters (blue, green and red) show that the peak transmission efficiencies are consistently 73%, 70% and 63%, respectively. Additionally, the effect of different angles of incidence on the transmittance spectra has also been presented. Hence, the obtained results strongly suggest that these filters can be potentially used for tuning the color of optical filters according to the desired applications