Herein, silicon nanoparticles (SiNPs) are coated with conducting hydrogel and wrapped with reduced graphene oxide (rGO) sheets via a facile and scalable solution-based sol-gel process. The in-situ polymerized polypyrrole (PPy) hydrogel forms an interconnected three-dimensional (3D) fiber matrix. Amine and hydroxyl groups from the hydrogel assist the encapsulation of the SiNPs through hydrogen bonding. The electro-conductive PPy fiber network and the wrapping of rGO offer efficient electron and ion transport pathways. The PPy/SiNPs/rGO electrodes can produce highly reversible capacities of 1312, 1285 and 1066 mAh g-1 at 100, 250 and 500 cycles at a current density of 2.1 A g-1, respectively.

It is known that n-Si solar cells have higher efficiency than p-Si solar cells. One of the problems connected with n-Si application for solar cell production is the difficulty of using Czochralski method for growing n-Si ingots, uniform in structure. The present paper examines the possibility of production of n-Si ingots, uniform in resistance, by neutron transmutation doping (NTD) for photovoltaics using the mathematical modeling method. The provided calculation data are obtained by MCU-RFFI/A accounting code with DLC/MCUDAT-1.0 constant library developed by «Kurchatov Institute» Russian Research Center. The MCU accounting code is used for solution of the neutron-transport equation by Monte-Carlo procedure on the basis of estimated nuclear data for arbitrary three-dimensional geometry systems.

The present paper provides the estimation of uniformity of neutron-flux density along the ingot length and radius; dependence of silicon resistance on duration of irradiation. These studies established the neutron flux density distribution along the ingot length and radius; regularities of silicon resistance changes on duration and intensity of irradiation.

The synthesis of inorganic/organic nanocomposite systems, well known as hybrid materials, represents a new class of polymeric materials, which combine properties of inorganic particles, such as barrier, optical, catalytic and conductive properties, among others, with flexibility and transparency of the organic polymer matrix, being easily processable. They could be applied in a diversity of areas such as textiles, inks, adhesion, biomaterials, paints, adhesives, and electronics [1-2]. Within the inorganic materials, silica nanoparticles which present excellent properties, such as high mechanical strength, thermal and chemical stability, and high surface area, have been widely incorporated into a polymer matrix to prepare polymer/silica hybrid materials [3-4]. It is reported that the quantity and the dispersion of nano-SiO2 in the polymer matrix have a real effect on the properties of the final materials [5-6].

In this work, hybrid silica/poly(butyl acrylate-methyl methacrylate-acrylic acid) (SiO2/P(BA-MMA-AA)) were synthesized via in situ semi-batch emulsion polymerization. The results showed that this process was produced with high monomer conversion and low formation of agglomerates. The thermomechanical behavior of the films obtained from latexes was characterized by using thermogravimetric analysis, differential scanning calorimetry, and tensile test. The nanocomposite films displays significantly improved mechanical and thermal properties over its pure polymer film, and also presents almost the same high transparency.

The influence of deep level defects lateral distribution in active layers of multicrystalline Si-based standard solar cells is investigated. Multicrystalline p-type Si wafers with 156×156 mm dimensions and 200 μm thickness were used for SCs preparation. One type of solar cells with conversion efficiency 20.4% was studied using capacitance voltage characteristics method (C-V) and by current deep level transient spectroscopy (I-DLTS). From various places along the diagonal of solar cell’s substrate with 20.4% efficiency nine pieces with an area ∼20 mm2 were extracted and studied. I-DLTS spectra of the five pieces from solar cell were measured. The features of deep levels defects concentration lateral distribution along the SC’s surface were studied.

In this project we have involved four high-achieving pre-university summer placement students in the development of undergraduate teaching materials, namely tutorial videos for first year undergraduate Electrical and Electronic Engineering lab, and computer simulations of didactic semiconductor structures for an Electrical Science first year compulsory taught module. Here we describe our approach and preliminary results.

To better understand the condition of commercial batteries used in Tesla EVs and stationary applications under real performing situations, this article focuses on tracking the temperature of commercial batteries during varying cycling conditions. We have found evidence of significant impact of cycling methods on batteries in ionic conductivity, inner impedance development, and structural change in both cathode and anode electrodes, which will be further analyzed by electrochemical impedance spectroscopy technique in the following research.

Due to the low degree of contact area and weak interfacial adhesion between CNTs and the growth substrate (Cu), large thermal contact resistance is the largest challenge preventing the use of vertically aligned CNTs (VACNTs) as a thermal interface material (TIM). Although significant research has been done regarding the growth of CNTs on reactive substrates by using an appropriate buffer layer in this group’s previous work, there are many unanswered questions associated with using VACNTs as a thermal interface material beyond synthesis. This effort extends prior work on carbon nanotube growth, by concentrating on ways to evaluate/measure CNT-based nanocomposite thermal resistance. In this study, with the use of a laser flash measurement system, the influence of CNT array properties (layer height and density) on the thermal diffusivity and thermal resistance of the CNT composite were investigated. Test results identify a correlation between the CNT array density/thickness and its thermal resistance.

We report an experimental study on the terahertz frequency dielectric properties of manganese cobalt ferrites (MnxCo1−xFe2O4) and nickel cobalt ferrites (NixCo1-xFe2O4) with three different stoichiometry each, x=0.3, x=0.5 and 0.7. Particularly, we present a comparison and discussion of the terahertz frequency indices of refraction of these two ferrites compositions. MnxCo1−xFe2O4 and NixCo1-xFe2O4 pellets with different Mn/Co and Ni/Co ratios (x=0.3, x=0.5 and x=0.7) were prepared by state-of-the-art ceramic processing. The morphology and chemical homogeneity of these ferrites were characterized by energy dispersive x-ray spectroscopy. We observed that the indexes of refraction for manganese cobalt ferrites are 3.22, 3.71 and 3.67 for ratios of 0.3, 0.5 and 0.7, respectively. In the case of nickel cobalt ferrite, the indexes of refraction are 3.53, 3.57 and 3.47 for ratios of 0.3, 0.5 and 0.7 respectively. We notice a substantial difference in the index of refraction for the Mn0.3Co0.7Fe2O4. This difference may be correlated to a secondary phase formed in this sample.

In the conventional crystalline silicon heterojunction solar cell with the intrinsic thin layer structure (the HIT solar cell), a p-doped thin film silicon or its alloy (pDTF-Si/A) is used as the hole collecting window layer. However, the parasitic absorbance in the pDTF-Si/A window layer, and the toxic, explosive diborane gas used for p-doping are limiting factors for achieving HIT cells with reduced processing costs and / or higher efficiencies. In this work, pDTF-Si/A is replaced by V2Ox, which is deposited by a simple physical vapor deposition technique. Due to the wide band gap of V2Ox, the HIT solar cell with the V2Ox window layer generates a higher short-circuit current density than the reference conventional HIT cell under 1 sun, and achieves an open-circuit voltage of 0.7 V. Furthermore, the charge carrier lifetime and pseudo-efficiency values of the HIT solar cell with the V2Ox window layer indicate that this cell has the potential to outperform the conventional HIT cell in terms of the power conversation efficiency under the standard test conditions.

Stretchable electronics represent an emerging class of devices that can be compressed, twisted and conform to very complicated shapes. The mechanical and electrical compliances of the technology promise to open up applications for healthcare, energy and entertainment purposes. However, advancement in the field has been hindered by material related constraints. Moreover, the current microfabrication facilities are optimized for rigid substrates such as silicon, which have significant different properties compared to elastomers. In this paper, four categories of enabling technologies for stretchable electronics commercialization are critically reviewed, namely: the novel design of stretchable structures, use of non-conventional materials, state-of-art printing techniques and also the patterning of electrodes or metal interconnects via conventional manufacturing techniques.

The electrophysical (donor-acceptor) properties of the of glass carbon (GC) surface before and after its electrochemical modification in conditions of chemisorption of fluorine-containing nanogroups were studied using the methods of scanning probe microscopy. The values of the coefficients characterizing local (for atomic-scale) electrophysical properties of the surface are calculated on the basis of obtained local spectral dependences of the tunneling current on the tunnelling voltage. Fluorination of the GC surface resulted in change of the ratio of its donor-acceptor atomic characteristics, acceleration of electrode processes, and increase of the overall tunneling activity of local places.

The field of composites materials has evolved from the use of traditional fillers (e.g. carbon and glass fibers) to nanoscale fillers that add unique and often multifunctional properties to the neat polymer. Because nanoparticles have extremely high surface to volume ratios, that alter the mobility of polymer chains near their interfaces, even a small addition of nanoparticles. These components have the potential to drastically transform the properties of the host polymers. While the last decade has observed several advances in the field of nanocomposites, some recent reviews have made it clear that definitive structure-property relationships are insufficient in the literature. The influence of inorganic TiO2 nanoparticles on the dynamic mechanical properties and microstructure of copolymer based on Butyl acrylate - Methyl methacrylate - Acrylic Acid has been investigated. The mechanical relaxations of the reinforced copolymer/TiO2 composites were studied under tension mode. Addition of TiO2 nanoparticles to acrylic copolymer produced a decrease in the glass transition temperature. Dynamic mechanical analysis (DMA) showed that the local motions associated with the alpha-transition (40°C) are enhanced as the frequency of oscillation increases, i.e. the tan d maximum increases at higher frequencies. The addition of TiO2 nanoparticles reduces significantly the strength of the alpha-transition. Thus, the cooperative molecular motions involving segments of the molecular chains associated with the alpha-transition were compromised by the presence of TiO2 nanoparticles resulting in a decrement of the storage modulus.