Publications by Year: 2018

Liu C, Wang S, Zhou Y, Yang H, Lu Q, Mandler D, Magdassi S, Tay CY, Long Y. Index-tunable anti-reflection coatings: Maximizing solar modulation ability for vanadium dioxide-based smart thermochromic glazing. J. Alloys Compd.Journal of Alloys and Compounds. 2018;731 :1197 - 1207.Abstract
V dioxide (VO2) nanoparticles with reversible semiconductor-metal phase transition holds the tremendous potential as a thermochromic material for the energy-saving smart glazing. However, the trade-off between improving the luminous transmittance (Tlum) while sacrificing the solar modulation ability (ΔTsol) hampers its bench-to-market translation. Previous studies of anti-reflection coatings (ARCs) focused primarily on increasing Tlum while neglecting ΔTsol, which is a key energy-saving determinant. The intrinsically low ΔTsol (<16%) is due to the fact that VO2 has a higher refractive index (RI) from 500 nm to 2200 nm wavelength (λ) below its crit. transition temp. (τc), which causes excessive reflection at a lower temp. This study aims to study ARCs with tunable RI (1.47-1.92 at λ = 550 nm) to improve the antireflection effect at a lower temp., thereby maximizing ΔTsol for various VO2 nanosubstrates, e.g. continuous thin films, nanocomposites, and periodic micro-patterning films. The best performing coatings could maximize ΔTsol (from 15.7% to 18.9%) and increase Tlum(avg) (from 39% to 44%) simultaneously, which surpasses the current bench-mark specifications ever reported for ARC-coated VO2 smart glazing. The cytotoxicity analyses evidence that ARCs are feasible to improve the cyto-compatibility of VO2 nanoparticles-based nanocomposites. The presented RI-tunable ARC, which circumvents the complex materials selection and optical design, not only paves the way for practical applications of VO2-based smart windows but also has extensive applications in the field of solar cells, optical lenses, smart display, etc. [on SciFinder(R)]
Yeshua T, Layani M, Dekhter R, Huebner U, Magdassi S, Lewis A. Micrometer to 15 nm Printing of Metallic Inks with Fountain Pen Nanolithography. SmallSmall. 2018;14 (1) :n/a.Abstract
The field of printed electronics is continually trying to reduce the dimensions of the elec. components. Here, a method of printing metallic lines with widths as small as 15 nm and up to a few micrometers using fountain pen nanolithog. (FPN) is shown. The FPN technique is based on a bent nanopipette with at. force feedback that acts similar to a nanopen. The geometry of the nanopen allows for rapid placement accuracy of the printing tip, on any desired location, with the highest of optical sub-micrometer resoln. Using this nanopen, investigations of various inks are undertaken together with instrumental and script-tool development that allows accurate printing of multiple layers. This has led to the printing of conductive lines using inks composed of silver nanoparticles and salt solns. of silver and copper. In addn., it is shown that the method can be applied to substrates of various materials with minimal effect on the dimension of the line. The line widths are varied by using nanopens with different orifices or by tailoring the wetting properties of the ink on the substrate. Metallic interconnections of conducting lines are reported. [on SciFinder(R)]
Agarwala S, Lee JM, Ng WL, Layani M, Yeong WY, Magdassi S. A novel 3D bioprinted flexible and biocompatible hydrogel bioelectronic platform. Biosens. Bioelectron.Biosensors & Bioelectronics. 2018;102 :365 - 371.Abstract
Bioelectronics platforms are gaining widespread attention as they provide a template to study the interactions between biol. species and electronics. Decoding the effect of the elec. signals on the cells and tissues holds the promise for treating the malignant tissue growth, regenerating organs and engineering new-age medical devices. This work is a step forward in this direction, where bio- and electronic materials co-exist on one platform without any need for post processing. We fabricate a freestanding and flexible hydrogel based platform using 3D bioprinting. The fabrication process is simple, easy and provides a flexible route to print materials with preferred shapes, size and spatial orientation. Through the design of interdigitated electrodes and heating coil, the platform can be tailored to print various circuits for different functionalities. The biocompatibility of the printed platform is tested using C2C12 murine myoblasts cell line. Furthermore, normal human dermal fibroblasts (primary cells) are also seeded on the platform to ascertain the compatibility. [on SciFinder(R)]
Li W, Tan JMR, Leow SW, Lie S, Magdassi S, Wong LH. Recent Progress in Solution-Processed Copper-Chalcogenide Thin-Film Solar Cells. Energy Technol. (Weinheim, Ger.)Energy Technology (Weinheim, Germany). 2018;6 (1) :46 - 59.Abstract
Soln.-based thin-film semiconductors offer a promising path for the mass prodn. of low-cost solar cells prepd. at low temps. Thin-film Cu-based chalcogenides such as Cu(In,Ga)(S,Se)2 (CIGSSe) and Cu2ZnSn(S,Se)4 (CZTSSe) hold great promise and have been regarded as viable candidates because of the abundance of their constituent elements and environmentally nontoxic nature. This Review summarizes the recent progress in soln.-processed Cu chalcogenides (CuInSe2, Cu(In,Ga)(S,Se)2, Cu2ZnSnS4, Cu2ZnSn(S,Se)4) for thin-film solar cells, with emphasis on the precursor soln. deposited by spray pyrolysis and spin coating. The general aspects, current status, and recent research highlights are introduced and analyzed in detail. Finally, the challenges and future prospects of these solar cells are also discussed. [on SciFinder(R)]
Wang N, Peh YK, Magdassi S, Long Y. Surface engineering on continuous VO2 thin films to improve thermochromic properties: Top-down acid etching and bottom-up self-patterning. J. Colloid Interface Sci.Journal of Colloid and Interface Science. 2018;512 :529 - 535.Abstract
Surface engineering is an effective method to improve the thermochromic performance of VO2. In this paper, an acid-etching top down method was proposed to tailor the VO2 surface morphol. from the continuous dense-packed surface to patterned structure, which exhibited the enhanced integrated visible transmittance (Tlum) and the enlarged solar modulating abilities (ΔTsol). Moreover, a self-patterning approach was also illustrated to improve the thermochromic properties. The proposed surface engineering methods represent a facile and cost-effective approach for enhancing thermochromic properties that could promote the application of VO2 thin films in smart windows. [on SciFinder(R)]
Wang S, Owusu KA, Mai L, Ke Y, Zhou Y, Hu P, Magdassi S, Long Y. Vanadium dioxide for energy conservation and energy storage applications: Synthesis and performance improvement. Appl. EnergyApplied Energy. 2018;211 :200 - 217.Abstract
Vanadium dioxide (VO2) is one of the most widely studied inorg. phase change material for energy storage and energy conservation applications. Monoclinic VO2 [VO2(M)] changes from semiconducting phase to metallic rutile phase at near room temp. and the resultant abrupt suppressed IR transmittance at high temp. makes it a potential candidate for thermochromic smart window application to cut the air-condition usage. Meanwhile proper elec. potential, stable structure and good interaction with lithium ions make metastable VO2 [VO2(B)] an attractive material for fabrication of electrodes for batteries and supercapacitors. However, some long-standing issues have plagued its usage. In thermochromic application, high transition temp. (τc), low luminous transmittance (Tlum) and undesirable solar modulation ability (ΔTsol) are the key problems, while in energy storage applications, short cycling lifetime and complex three-dimension microstructure are the major challenges. The common methods to produce VO2 polymorph are phys. vapor deposition (PVD), chem. vapor deposition (CVD), sol-gel synthesis, and hydrothermal method. CVD is an intensively studied method due to its ability to produce uniform films with precise stoichiometry, phase and morphol. control. This paper reviews the various CVD techniques to produce VO2 with controlled phases and the ternary diagram shows the relationship between film stoichiometry and various process conditions. The difference between the various CVD systems are commented and the process window to produce VO2 are tabulated. Some strategies to improve VO2's performance in both energy conservation and energy storage applications are discussed. [on SciFinder(R)]