Banin U, Soreq H, Magdassi S, Waiskopf N, Ben-Shahar Y, Ashok Pawar A, Halivni S.; 2017. Hybrid nanoparticles as photoinitiators.Abstract
The invention provides a novel photoinitiator in the form of a hybrid nanoparticle constructed of a semiconductor and metallic regions, and uses thereof. [on SciFinder(R)]
Farraj Y, Bielmann M, Magdassi S. Inkjet printing and rapid ebeam sintering enable formation of highly conductive patterns in roll to roll process. RSC Adv.RSC Advances. 2017;7 (25) :15463 - 15467.Abstract
Electron beam sintering at ambient pressure is demonstrated for the first time, in formation of highly conductive silver patterns composed of silver nanoparticles. Silver nanoparticles were inkjet printed on a plastic substrate, followed by rapid ebeam irradn., without causing any damage to the substrate. It was found that exposing the printed silver patterns to a dose of 600 kGy yielded a resistivity as low as 4.5 μΩ cm, which is only 2.8 times higher than that of the bulk silver. The effect of various parameters related to electron energy and penetration depth on the sintering efficiency was evaluated. This finding reveals the applicability of ebeam technol. in printed electronics for large-scale, roll-to-roll, high throughput printing processes. [on SciFinder(R)]
Wang N, Goh QS, Lee PL, Magdassi S, Long Y. One-step hydrothermal synthesis of rare earth/W-codoped VO2 nanoparticles: Reduced phase transition temperature and improved thermochromic properties. J. Alloys Compd.Journal of Alloys and Compounds. 2017;711 :222 - 228.Abstract
As a reversible thermochromic material, V dioxide (VO2) is a promising candidate for smart window applications. The trade-off between the integrated visible transmission (Tlum) and the solar modulating ability (ΔTsol), as well as the high phase transition temp. (τc∼68°) are regarded as the main obstacle for practical applications of pure VO2 nanomaterials. The combination of both high τc reducing efficiency of W and improving Tlum/ΔTsol properties of RE (rare earth: Eu, Tb), herein lies the purpose of RE/W-codoping to enhance the thermochromic performance. The RE/W-codoped VO2 nanoparticles were synthesized under hydrothermal conditions, and exhibited grain size of <100 nm. The smart window which was fabricated by coating RE/W-codoped VO2 nanoparticles onto glass, exhibits a thermochromic performance with a combination Tlum = 40%, ΔTsol = 6.3%, τc = 40.8° or Tlum = 63%, ΔTsol = 3.6%, τc = 31.9°, indicating the largely reduced absorption compared with the single W doping. Under the RE/W-codoping conditions, the ionic radius of the RE3+ cations controlled the crystallinity of the VO2 particles and the electron/hole carrier counteraction as well as the competition between the strain and the hole carrier played a vital role in modulating the τc of the VO2 products. The findings should be meaningful for studying the codoping mechanisms for VO2 nanomaterials. [on SciFinder(R)]
Li W, Su Z, Tan JMR, Chiam SY, Seng HL, Magdassi S, Wong LH. Revealing the Role of Potassium Treatment in CZTSSe Thin Film Solar Cells. Chem. Mater.Chemistry of Materials. 2017 :Ahead of Print.Abstract
Potassium (K) post-treatment on CIGSSe has been shown to yield the highest efficiency reported to date. However, very little is known on the effect of K doping in CZTSSe and the mechanism behind the efficiency improvement. Here we reveal the mechanism by which K enhances the charge sepn. in CZTSSe. We show that K accumulates at the CdS/CZTSSe, passivating the recombination at the front interface and improving carrier collection. K is also found to accumulate at the CZTSSe/Mo interface and facilitates the diffusion of Cd into the absorber which affects the morphol. and grain growth of CZTSSe. As revealed by the C-V, external quantum efficiency, and color J-V test, K doping significantly increases the carrier d., improves carrier collection, and passivates the front interface and grain boundaries, leading to the enhancement of Voc and Jsc. The av. power conversion efficiency has been promoted from 5% to above 7%, and the best 7.78% efficiency has been achieved for the 1.5 mol % K-doped CZTSSe device. This work offers some new insights into the K doping effects on CZTSSe via soln.-based approach and demonstrates the potential of facile control of K doping for further improvement of CZTSSe thin film solar cells. [on SciFinder(R)]
Rosen YS, Yakushenko A, Offenhausser A, Magdassi S. Self-Reducing Copper Precursor Inks and Photonic Additive Yield Conductive Patterns under Intense Pulsed Light. ACS OmegaACS Omega. 2017;2 (2) :573 - 581.Abstract
Printing conducting copper interconnections on plastic substrates is of growing interest in the field of printed electronics. Photonic curing of copper inks with intense pulsed light (IPL) is a promising process as it is very fast, and so can be incorporated in roll-to-roll prodn. We report on using IPL for obtaining conductive patterns from inks composed of submicron particles of copper formate, a copper precursor that has a self-redn. property. Decompn. of copper formate can be performed by IPL, and is affected both by the mode of energy application and the properties of the printed precursor layer. The energy application mode was controlled by altering three pulse parameters: duration, intensity, and repetitions at 1 Hz. Since the decompn. results from energy transfer via light absorption, carbon nanotubes (CNTs) were added to the ink to increase the absorbance. We show that there is a strict set of IPL parameters necessary to obtain conductive copper patterns. Finally we show that by adding as little as 0.5 wt.% SWCNTs to the ink, the absorptance was enhanced by about 50%, and the threshold energy required to obtain a conductive pattern decreased by ∼25%. These results have major implications for tailoring inks intended for IPL processing. [on SciFinder(R)]
Mishra P, Balaji APB, Dhal PK, Suresh KRS, Mukherjee A, Chandrasekaran N, Magdassi S, Margulis K, Tyagi BK. Stability of nano-sized permethrin in its colloidal state and its effect on the physiological and biochemical profile of Culex tritaeniorhynchus larvae. Bull Entomol ResBulletin of entomological research. 2017 :1 - 13.Abstract
The occurrence of pesticidal pollution in the environment and the resistance in the mosquito species makes an urge for the safer and an effective pesticide. Permethrin, a poorly water-soluble pyrethroid pesticide, was formulated into a hydrodispersible nanopowder through rapid solvent evaporation of pesticide-loaded oil in water microemulsion. Stability studies confirmed that the nanopermethrin dispersion was stable in paddy field water for 5 days with the mean particle sizes of 175.3 ± 0.75 nm and zeta potential of -30.6 ± 0.62 mV. The instability rate of the nanopermethrin particles was greater in alkaline (pH 10) medium when compared with the neutral (pH 7) and acidic (pH 4) dispersion medium. The colloidal dispersion at 45°C was found to be less stable compared with the dispersions at 25 and 5°C. The 12- and 24-h lethal indices (LC50) for nanopermethrin were found to be 0.057 and 0.014 mg l-1, respectively. These results were corroborative with the severity of damages observed in the mosquito larvae manifested in epithelial cells and the evacuation of the midgut contents. Further, the results were substantiated by the decrease in cellular biomolecules and biomarker enzyme activity in nanopermethrin treated larvae when compared to bulk and control treatment.[on SciFinder (R)]
Liu C, Long Y, Magdassi S, Mandler D. Ionic strength induced electrodeposition: a universal approach for nanomaterial deposition at selective areas. NanoscaleNanoscale. 2017;9 (2) :485 - 490.Abstract
An appealing alternative approach to the conventional electrochem. deposition is presented, which can be universally utilized to form nanomaterial coatings from their aq. dispersions without involving their oxidn.-redn. It is based on altering the ionic strength by elec. potential in the vicinity of the electrode surface, which causes the nanomaterials to deposit. The concept has been demonstrated for four different systems. [on SciFinder(R)]
Zhou Y, Layani M, Boey FYC, Sokolov I, Magdassi S, Long Y. Electro-Thermochromic Devices Composed of Self-Assembled Transparent Electrodes and Hydrogels. Adv. Mater. Technol. (Weinheim, Ger.)Advanced Materials Technologies (Weinheim, Germany). 2016;1 (5) :n/a.
Kamyshny A, Magdassi S. Microencapsulation., in Encycl. Surf. Colloid Sci. (3rd Ed.). Vol 6. CRC Press ; 2016 :4636 - 4648.Abstract
Microencapsulation is a process by which a gas, liq., or solid material (core) is packaged inside capsules of a second material (shell), which protects and isolates the core material from the surrounding environment and adjusts its properties in accordance with requirements. In other words, a microcapsule (MC) is a reservoir contg. an active substance surrounded by a membrane (typically made of a natural or synthetic polymer). MCs are spherical or irregular particles in the size range from 50 nm to a few hundred micrometers; the most widely used are capsules of micron size (capsules smaller than I mm are often classified as nanocapsules, and capsules larger than 1000 mm are called macrocapsules or beads). Com. MCs typically have a diam. between 3 and 800 mm. In this entry we focus on the manufg. methodologies and mechanisms of microencapsulation, including evaluation of the nature and properties of core and shell ingredients. Current and potential applications of MCs in various fields of chem. and life sciences, as well as in related industries, will also be presented. [on SciFinder(R)]
Ke Y, Balin I, Wang N, Lu Q, Tok AIY, White TJ, Magdassi S, Abdulhalim I, Long Y. Two-Dimensional SiO2/VO2 Photonic Crystals with Statically Visible and Dynamically Infrared Modulated for Smart Window Deployment. ACS Appl. Mater. InterfacesACS Applied Materials & Interfaces. 2016;8 (48) :33112 - 33120.Abstract
Two-dimensional (2D) photonic structures, widely used for generating photonic band gaps (PBG) in a variety of materials, are for the 1st time integrated with the temp.-dependent phase change of VO2. VO2 possesses thermochromic properties, whose potential remains unrealized due to an undesirable yellow-brown color. A SiO2/VO2 core/shell 2D photonic crystal is demonstrated to exhibit static visible light tunability and dynamic near-IR (NIR) modulation. Three-dimensional (3D) finite difference time domain (FDTD) simulations predict that the transmittance can be tuned across the visible spectrum, while maintaining good solar regulation efficiency (ΔTsol = 11.0%) and high solar transmittance (Tlum = 49.6%). The color changes of VO2 films are accompanied by NIR modulation. This work presents a novel way to manipulate VO2 photonic structures to modulate light transmission as a function of wavelength at different temps. [on SciFinder(R)]
Halevi O, Jiang H, Kloc C, Magdassi S. Additive manufacturing of micrometric crystallization vessels and single crystals. Sci. Rep.Scientific Reports. 2016;6 :36786.Abstract
We present an all-additive manufg. method that is performed at mild conditions, for the formation of org. single crystals at specific locations, without any photolithog. prefabrication process. The method is composed of two steps; inkjet printing of a confinement frame, composed of a water sol. electrolyte. Then, an org. semiconductor soln. is printed within the confinement to form a nucleus at a specific location, followed by addnl. printing, which led to the growth of a single crystal. The specific geometry of the confinement enables control of the specific locations of the single crystals, while sepg. the nucleation and crystal growth processes. By this method, we printed single crystals of perylene, which are suitable for the formation of OFETs. Moreover, since this method is based on a simple and controllable wet deposition process, it enables formation of arrays of single crystals at specific locations, which is a prerequisite for mass prodn. of active org. elements on flexible substrates. [on SciFinder(R)]
Pajor-Swierzy A, Farraj Y, Kamyshny A, Magdassi S. Air stable copper-silver core-shell submicron particles: Synthesis and conductive ink formulation. Colloids Surf., AColloids and Surfaces, A: Physicochemical and Engineering Aspects. 2016 :Ahead of Print.Abstract
We report on the synthesis of copper-silver core-shell (Cu@Ag) particles with about 1 μm-diam. Cu core coated with a thin (∼20 nm) silver shell, for application in printed electronics as low cost conductive ink. The process is based on using the environmentally friendly sodium formaldehyde sulfoxylate dehydrate as a reducing agent for copper ions and two types of polymeric stabilizers (nonionic PVP and anionic PAA). The formation of core-shell particles is followed by transmetallation reaction on the surface of the Cu particles, where copper atoms function as the reducer for silver ions. Characterization of the submicron particles by SEM, EDS and XRD confirm the core-shell structure. The resulting Cu@Ag particles enable overcoming a major challenge in copper ink, their rapid oxidn. in air. It was found that ink formulations based on propylene glycol as the liq. vehicle and contg. a silicone based wetting agent possesses the optimal characteristics (wetting, sintering) for printing on a glass substrate. To obtain conductive metallic structures, thermal sintering of metallic patterns was used. The Cu@Ag coating are stable to oxidn. for at least 6 mo at room temp., and also during sintering process which is carried out at temps. up to 250 °C. The cond. of Cu@Ag coatings after sintering at 250 °C was high, 16% of that for bulk copper. [on SciFinder(R)]
Bera RK, Mhaisalkar SG, Mandler D, Magdassi S. Formation and performance of highly absorbing solar thermal coating based on carbon nanotubes and boehmite. Energy Convers. Manage.Energy Conversion and Management. 2016;120 :287 - 293.Abstract
A major component of solar thermal systems is the solar absorber, which converts light into heat. We report on achieving high absorptance, excellent adhesion, and high thermal stability of carbon nanotube-based black coatings by applying a layer of Boehmite (AlOOH) on top of the carbon nanotube (CNT) film by soln.-processed spray deposition. The CNT layer made-up by spraying, functions as an absorbing layer and the AlOOH serves as an anti-reflecting and protecting film. The anti-reflecting property of AlOOH layer effectively increases the absorptance of CNT coating by decreasing the reflectance. The effect of the thickness of AlOOH layer on the absorptance, adhesion, and thermal stability of the resulting CNT/AlOOH coating was investigated. The CNT/AlOOH coating with optimized thickness of AlOOH layer shows very high absorptance (α) of 0.975. The adhesion of the coating is in the range of 95-100% with significant increase of thermal stability. This new approach is expected to open new possibilities for fabricating low-cost, highly efficient and thermally stable solar-thermal devices which are based on simple coating processes. [on SciFinder(R)]
Misra RK, Aharon S, Layani M, Magdassi S, Etgar L. A mesoporous-planar hybrid architecture of methylammonium lead iodide perovskite based solar cells. J. Mater. Chem. AJournal of Materials Chemistry A: Materials for Energy and Sustainability. 2016 :Ahead of Print.Abstract
We report a hybrid mesoporous-planar architecture of methylammonium lead iodide perovskite based solar cells, to combine the benefits of both the mesoporous and planar architectures in a single device. A mesoporous-TiO2 grid was fabricated on a compact TiO2 layer, through a self-assembly process based on directional wetting, providing regions with and without mesoporous-TiO2, followed by perovskite deposition and back contact evapn. (hybrid cells). The hybrid cells showed up to 10.7% power conversion efficiency (PCE) as compared to 13.5% and 6.3% for their mesoporous and planar counterparts, resp. Interestingly, the hybrid cells are found to show a short circuit c.d. (Jsc) as high as the Jsc of the mesoporous TiO2 based cells and proved to conserve the c.d. even in the absence of mesoporous-TiO2 from planar parts of the hybrid cells. The cells showed the best fill factor as compared to their mesoporous and planar counterparts. The areal variation in the meso to planar ratio has also been realized by changing the grid size to demonstrate the effect of the architecture on the cell performance. Charge extn. measurements have been used to obtain insight into the recombination inside different solar cells architectures. The hybrid cell structure emerged as a novel promising design for perovskite solar cells. [on SciFinder(R)]
Lu Q, Liu C, Wang N, Magdassi S, Mandler D, Long Y. Periodic micro-patterned VO2 thermochromic films by mesh printing. J. Mater. Chem. CJournal of Materials Chemistry C: Materials for Optical and Electronic Devices. 2016 :Ahead of Print.Abstract
VO2 has garnered much attention in recent years as a promising candidate for thermochromic window applications due to rising awareness about energy conservation. However, the trade-off between improving the luminous transmittance (Tlum) and solar modulation ability (ΔTsol) limits the commercialization of VO2-based smart windows. Four major nanostructuring approaches were implemented to enhance both Tlum and ΔTsol, namely nanocomposites, nanoporous films, biomimetic moth-eye structures and anti-reflection coating (ARC) multilayers. This work demonstrates a novel approach that fabricates periodic, micro-patterned structures of VO2 using a facile screen printing method. The micro-patterned structure is able to favorably transmit visible light without sacrificing high near-IR modulation, and the patterned film shows improved Tlum (67% vs. 60%) and ΔTsol (8.8% vs. 6.9%) compared with continuous films. By varying the thickness, periodicity and solid concn., this approach can give a ΔTsol of 14.9% combined with a Tlum of 43.3%, which is comparable, if not superior to, some of the best reported results found using other approaches. [on SciFinder(R)]
Portnoy E, Polyak B, Inbar D, Ben-Hur T, Ekstein D, Kenan G, Rai A, Wehrli SL, Roberts TPL, Bishara A, et al. Tracking inflammation in the epileptic rat brain by bi-functional fluorescent and magnetic nanoparticles. NanomedicineNanomedicine : nanotechnology, biology, and medicine. 2016;12 (5) :1335 - 45.Abstract
Correct localization of epileptic foci can improve surgical outcome in patients with drug-resistant seizures. Our aim was to demonstrate that systemically injected nanoparticles identify activated immune cells, which have been reported to accumulate in epileptogenic brain tissue. Fluorescent and magnetite-labeled nanoparticles were injected intravenously to rats with lithium-pilocarpine-induced chronic epilepsy. Cerebral uptake was studied ex vivo by confocal microscopy and MRI. Cellular uptake and biological effects were characterized in vitro in murine monocytes and microglia cell lines. Microscopy confirmed that the nanoparticles selectively accumulate within myeloid cells in the hippocampus, in association with inflammation. The nanoparticle signal was also detectable by MRI. The in vitro studies demonstrate rapid nanoparticle uptake and good cellular tolerability. We show that nanoparticles can target myeloid cells in epileptogenic brain tissue. This system can contribute to pre-surgical and intra-surgical localization of epileptic foci, and assist in detecting immune system involvement in epilepsy.[on SciFinder (R)]
Zarek M, Layani M, Cooperstein I, Sachyani E, Cohn D, Magdassi S. 3D Printing of Shape Memory Polymers for Flexible Electronic Devices. Adv. Mater. (Weinheim, Ger.)Advanced Materials (Weinheim, Germany). 2016;28 (22) :4449 - 4454.Abstract
The authors describe a general and facile method based on 3D printing methacrylated macromonomers to fabricate shape memory objects that can be used in flexible and responsive elec. circuits. Such responsive objects can be used in fabrication of soft robotics, minimal invasive medical devices, sensors, and wearable electronics. The use of 3D printing overcomes the poor processing characteristics of thermosets and enables complex geometries that are not easily accessible by other techniques. [on SciFinder(R)]
Pawar AA, Saada G, Cooperstein I, Larush L, Magdassi S, Jackman JA, Tabaei SR, Cho N-J. High-performance 3D printing of hydrogels by water-dispersible photoinitiator nanoparticles. Sci AdvScience advances. 2016;2 (4) :e1501381.Abstract
In the absence of water-soluble photoinitiators with high absorbance in the ultraviolet (UV)-visible range, rapid three-dimensional (3D) printing of hydrogels for tissue engineering is challenging. A new approach enabling rapid 3D printing of hydrogels in aqueous solutions is presented on the basis of UV-curable inks containing nanoparticles of highly efficient but water-insoluble photoinitiators. The extinction coefficient of the new water-dispersible nanoparticles of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) is more than 300 times larger than the best and most used commercially available water-soluble photoinitiator. The TPO nanoparticles absorb significantly in the range from 385 to 420 nm, making them suitable for use in commercially available, low-cost, light-emitting diode-based 3D printers using digital light processing. The polymerization rate at this range is very fast and enables 3D printing that otherwise is impossible to perform without adding solvents. The TPO nanoparticles were prepared by rapid conversion of volatile microemulsions into water-dispersible powder, a process that can be used for a variety of photoinitiators. Such water-dispersible photoinitiator nanoparticles open many opportunities to enable rapid 3D printing of structures prepared in aqueous solutions while bringing environmental advantages by using low-energy curing systems and avoiding the need for solvents.[on SciFinder (R)]
Banin U, Magdassi S, Shemesh S, Halivni S, Vinetsky Y.; 2016. Patterns of fluorescent seeded nanorods.Abstract
The invention provides novel means for fabricating patterns and objects comprising nanorods, while reducing inter-particle interaction. [on SciFinder(R)]
Cai P, Layani M, Leow WR, Amini S, Liu Z, Qi D, Hu B, Wu Y-L, Miserez A, Magdassi S, et al. Bio-Inspired Mechanotactic Hybrids for Orchestrating Traction-Mediated Epithelial Migration. Adv. Mater. (Weinheim, Ger.). 2016;28 (16) :3102 - 3110.Abstract

A platform of mechanotactic hybrids is established by projecting lateral gradients of apparent interfacial stiffness onto the planar surface of a compliant hydrogel layer using an underlying rigid substrate with microstructures inherited from 3D printed molds. Using this platform, the mechanistic coupling of epithelial migration with the stiffness of the extracellular matrix (ECM) is found to be independent of the interfacial compositional and topog. cues. [on SciFinder(R)]