Organic/Polymeric Semiconductor (OSC) based devices have been under extensive study for the past three decades due to their intrinsic potential advantages such as lightweight, mechanical flexibility, biocompatibility, low toxicity, abundant material availability, low cost of processing, etc. A phototransistor incorporates the properties and functions of a transistor and photodetector. In this study, a phototransistor based on a donor/acceptor (D/A) pair (photo-doping) was studied and demonstrated. Unlike in organic photovoltaics (OPV) where 1:1 proportion by mass of the donor:acceptor is utilized to make up the active layer, that ratio appears to be too high for phototransistor applications. According to literature, this 1:1 concentration leads to low overall device performance, lack of I-V curve saturation (kink effect), and bipolar behavior. By altering fabrication techniques and doping concentrations, we were able to demonstrate a donor/acceptor based phototransistor with p-type characteristics with improved performance. In this work, we fabricated a high-performance OFET based on a very small amount of Phenyl-C71-butyric acid methyl ester (PCBM) doped into a Poly(3-hexylthiophene) (P3HT) host. With this work, a greater understanding behind the optimization of D/A based phototransistors is advanced.

A multiscale Green's function method, based upon a solution of the Dyson equation, is described for modeling the strain field due to a vacancy or any other point defect in graphene and other 2D materials. Numerical results are presented using a fourth-neighbor force-constant model for the purpose of illustration.

Surface modification of Engelhard titanosilicate (ETS-10) with silver (Ag) was carried out in efforts to promote the photocatalytic activity of ETS-10 towards the degradation of methylene blue (MB) under visible light irradiation. The core-shell heterostructure encapsulates the Ag nanoparticles, which would otherwise dislodge from the surface of ETS-10. The Ag@ETS-10 core-shell heterostructured photocatalyst was prepared by the photodeposition of Ag nanoparticles onto ETS-10 crystals to form the Ag-ETS-10 core, followed by secondary growth of ETS-10 shell using the Ag-ETS-10 as seeds. Ag@ETS-10 showed absorption in the visible light region, as well as a red shift in the UV region, compared to the unmodified ETS-10. The extent of shell growth depended on the seeding level. Increasing the seeding level from 1 wt.% to 50 wt.% resulted in a decreased mode of the particle size distribution of the products, and thus a decreased shell thickness. The Ag@ETS-10 photocatalyst grown using 50 wt.% seeding level (i.e., ∼0.1 μm shell) showed higher photocatalytic activity in the photodegradation of MB under visible light irradiation (k = 0.0159 min-1) than the unmodified ETS-10 sample (k = 0.007 min-1). However, the Ag@ETS-10 photocatalyst grown using 1 wt. % seeding levels (i.e., ∼ 0.8 μm shell) showed lower photocatalytic activity compared to the Ag@ETS-10 photocatalyst grown using 50 wt.% seeding level (i.e., ∼ 0.1 μm shell). This was attributed to the suppression of the plasmon resonance peak when a thicker ETS-10 shell was grown around the Ag-ETS-10 core.

The polymerization of 3,4-ethylenedioxythiophene (EDOT) onto nanosilica (SiO2) was synthesized in this study by using supercritical carbon dioxide (SCCO2). With the addition of dopants of p-toluenesulfonic acid (p-TSA) or decylbenzene sulfonic acid (DBSA), the PEDOT/SiO2 composite became conductive. The product was characterized by FTIR spectroscopy and the core-shell structure was confirmed through the TEM images. The electrical properties were analyzed by UV-vis absorbance and four-point probe measurement. DBSA is shown as the better dopants with the molar ratio (DBSA/EDOT) of 0.2 at the reaction time of 48 hours. The maximum coating percentage is 63 wt% under the optimal operation conditions at 40oC and 280 bar. The conductivity is tuned up to 6.6×10-2 S/cm after the coating process.

In this work, the first results of the effects of temperature during the production of Se2- ions and the effect during the interaction of Cd2+ and Se2- ions in the synthesis process of CdSe nanoparticles are presented. The synthesis of CdSe was carried out by the colloidal technique, in the first one we used a temperature of 63 °C to produce Se2- ions and in the second one an interaction temperature of 49 °C. The samples were characterized using a Scanning Electron Microscope (SEM) and a Scanning Tunneling Microscope (STM). From the SEM micrographs it was possible to identify the thorns formation and irregular islands. STM micrographs reveal elliptical shapes with a regular electron cloud profile.

Several techniques have been employed for large-scale synthesis of group 10 transition metal dichalcogenides (TMDCs) based on platinum and palladium for nano- and opto-electronic device applications. Nickel Sulphides (NixSy), belonging to group 10 TMDC family, have been widely explored in the field of energy storage devices such as batteries and supercapacitors, etc. and commonly synthesized through the solution process or hydrothermal methods. However, the high-quality thin film growth of NixSy for nanoelectronic applications remains a central challenge. Here, we report the chemical vapor deposition (CVD) growth of NiS2 thin film onto a two-inch SiO2/Si substrate, for the first time. Techniques such as X-ray photoelectron spectroscopy, X-ray Diffraction, Raman Spectroscopy, Scanning Electron Microscopy, have been used to analyse the quality of this CVD grown NiS2 thin film. A high-quality crystalline thin film of thickness up to a few nanometres (~28 nm) of NiS2 has been analysed here. We also fabricated a field-effect device based on NiS2 thin film using interdigitated electrodes by optical lithography. The electrical performance of the fabricated device is characterized at room temperature. On applying the drain voltage from -2 to +2 V, the device shows drain current in the range of 10-9 A before annealing and in the range of 10-6 A after annealing. This, being comparable to that from devices based on MoS2 and other two-dimensional materials, projects CVD grown NiS2 as a good alternative material for nanoelectronic devices.

Bismuth telluride have regained significant attention as a prototype of topological insulator. Thin films of high quality have been investigated as a basic platform for novel spintronic devices. Low mobility of bismuth and high desorption coefficient of telluride compose a scenario where growth parameters have drastic effects on structural and electronic properties of the films. Recently [J. Phys. Chem. C 2019, 123, 24818−24825], a detailed investigation has been performed on the dynamics of defects in epitaxial films of this material, revealing the impact of film/substrate lattice misfit on the films’ lateral coherence. Very small lattice misfit (<0.05%) are expected to have no influence on quality of epitaxial system with atomic layers weakly bonded to each other by van der Waals forces, contrarily to what was observed. In this work, we investigate the correlation between lattice misfit and size and morphology of the film crystalline domains. Three-dimensional reciprocal-space maps of film Bragg reflections obtained with synchrotron X-rays are used to visualize the spatial conformation of the crystallographic domains through film thickness, while atomic force microscopy images provide direct information of the domains morphology at the film surface.

In a bid to further reduce the cost of the front Ag contact metallization in Si solar cells, Cu is the potential alternative to replace the Ag in the Ag paste. However, this requires an understanding of the contact mechanism of screen-printable Ag/Cu paste in Si solar cell through rapid thermal process. The pastes with different weight percent of Cu (0 wt%, 25 wt% and 50 wt%) were used and the Voc of the cells was reduced with the increasing weight percent of Cu. This is because the presence of Cu in the paste changed the microstructure of the Ag/Cu/Si contact through Cu doping of the glass frits and hence increasing the Tg of the glass. The increased Tg of the glass impeded the uniform spreading of the molten glass and resulted in poor wetting and etching of the SiNx, which impacted the contact as evident in ideality factor of less than unity. This also led to the formation of agglomerated Ag crystallites with features of 700 nm in length and 200 nm in depth, which is close to the p-n junction, of which depth is ∼300 nm. However, the interface glass layer acted as an effective diffusion barrier layer to prevent Cu atoms from diffusing into the Si emitter, which is quite remarkable for Cu not to diffuse into silicon at high temperature. Further investigation of the Ag/Cu contacts with the conductive AFM in conjunction with the SEM and STEM analyses revealed that the growth of Ag crystallites in the Si emitter is responsible for carrier conduction the gridlines as with the pure Ag paste.

Sarin gas is a dangerous chemical warfare agent (CWA). It is a nerve agent capable of bringing a person to death in about 15 minutes. A lethal concentration of sarin molecules in air is about 30 mg/m3. Experimental research on this gas requires very careful safety protocols for handling and storage. Therefore, theoretical and computational studies on sarin gas are very welcome and might provide important safe guides towards the management of this lethal substance. In this work, we investigated the interactions between sarin, air and nanoporous graphene, using tools of classical molecular dynamics simulations. Aiming to cast some light in the possible sarin selective filtration by graphene, we designed a bipartite simulation box with a porous graphene nanosheet placed at the middle. Sarin and air molecules were initially placed only on one side of the box so as to create an initial pressure towards the passage of both to the other side. The box dimensions were chosen so that the hole in the graphene was the only possible way through which sarin and air molecules can get to the other side of the box. The number of molecules that passed through the hole in graphene was monitored during 10 ns of simulation and the results for different temperatures were compared. The results show that, as far as the size of the holes are small, van der Waals forces between graphene and the molecules play a significant role on keeping sarin near graphene, at room temperature.

Silicon has attracted particular attention as a potential high capacity material for lithium based batteries. However, the application of Si-based electrodes remains challenging, in major part due to its significant irreversible energy loss during cycling. Here isothermal microcalorimetry (IMC) is demonstrated to be a precise and operando characterization method for tracking a battery's thermal behaviour and deconvoluting the contributions from electrochemical polarization, entropy change, and parasitic reactions. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and x-ray powder diffraction (XRD) further elucidate the Si reactivity in conjunction with the IMC.

In high efficiency organic-inorganic perovskite solar cells formed as a multilayer structure, the hole transporting layer (HTL) at the perovskite absorber layer interface has a critical role. Organic HTLs based on Spiro-OMeTAD and PTAA have led to high efficiencies but displayed poor long-term stability and involves expensive purification processes that hinders universal low-cost commercialization goals for perovskite solar cells. Though as an inorganic alternative, transition metal chalcogenides have been investigated for HTL recently, the hot-injection method often used in synthesis has shown poor reproducibility and difficulty in scaling-up. In this work we demonstrate an ab initio facile inexpensive scalable synthesis of transition metal dichalcogenide (TiS2) by electrodeposition from ionic liquids as a low-cost inorganic HTL for perovskite solar cells. The TiS2 thin films were electrodeposited from choline chloride–urea eutectic based ionic liquid electrolytes at 80°C with Na2S2O3 as sulphur and TiCl4 as titanium source. From cyclic voltammetry studies the deposition potential of TiS2 was optimized at -0.8V vs Pt. The as-deposited TiS2 HTL exhibited polycrystalline structure with preferential growth along (001), (100), (002), (102), (110), (111) planes. The Raman spectroscopy of the films showed peaks around 225 cm−1 and 332 cm−1 attributed to the Eg and A1 g Raman modes respectively. The synthesized thin films demonstrated sharp optical bandgap edge along with bandgap tunability as the bandgap (direct) decreased from 1.53 eV to 1.49 eV, 1.40 eV, and 1.34 eV with gradual change in deposition potential from −0.8 V to −0.9 V, −1.0 V, and −1.1 V vs Pt, respectively. This aspect has potential for alignment of valance band edge in facilitating the hole transport at the perovskite-TiS2 interface. The absorption coefficient in visible-light range of the as-deposited TiS2 thin films likewise has shown a dependence on the synthesis potential which is highly conducive for application as an HTL in multilayer solar cell structure. The TiS2 thin films were observed to be p-type as shown from the Hall effect studies with a carrier mobility up to 14.4 cm2V−1s−1. A detailed study of the effect of the synthesis parameters on the structural, optical, band-edge, and electronic properties of TiS2 thin films suitable for application as HTL in perovskite solar cells is presented.

The paper provides generic overview of legal and regulatory framework of radioactive waste management activities held in Russian Federation and national operator responsibilities and accomplishments. It gives a short description of waste classification scheme used and plans for radioactive waste disposal. In particular the paper provides information on the plans of the FEDERAL STATE UNITARY ENTERPRISE "National operator for radioactive waste management" to construct and operate several near-surface disposal facilities for low and intermediate level waste with total capacity up to 550 000 cubic meter. The paper also provides detailed information on the steps of high-level waste disposal program including site-selection, construction phase of the underground research laboratory (URL) near the city of Zheleznogorsk, Krasnoyarsk Region and research program after the construction of the URL. The paper also describes Russian system and state policy in the field of RW management and gives recommendations for future implementers.

The direct laser-deposited Inconel 718 (IN718) specimens were produced using 1073 nm, high power continuous wave (CW), IPG Ytterbium fibre laser and in-situ heat treatment. The laser power and in-situ heat treatment temperature were fixed while varying the laser scanning speed from 0.83 to 2.50 cm/s. The microstructure and micro-hardness of the IN718 specimens were characterized using an optical microscope (OM), scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDS or EDX) and Vickers system. The microstructure of the specimens consists of γ-matrix as the primary phase, Nb-rich particles, constitutional liquation cave, liquation cracking and ductility-dip cracks. It was found that the micro-hardness profile of the IN718 specimens was gradually increased with the increase of the distance from the surface.

A range of stoichiometric and mixed A-site cation brannerite glass-ceramics have been synthesised and characterised. The formation of UTi2O6 in glass is reliant on ensuring all uranium remains tetravalent by processing in an inert atmosphere. ThTi2O6 forms in glass under both inert and oxidising atmospheres due to the lack of other easily available oxidation states. CeTi2O6 could not be made to form within this glass system. The formation of A0.5B0.5Ti2O6 phases depends strongly on the oxidation states of the A and B cations available in the process atmosphere, with the most successful compositions having an average final oxidation state of (A,B)4+. Mixed cation brannerite compositions that formed in argon include U0.75Th0.25Ti2O6 and U0.71Ce0.29Ti2O6. Those forming in air include U0.23Th0.77Ti2O6, Th0.37Ce0.63Ti2O6, and U0.41Ce0.59Ti2O6.

Articular cartilage plays an important role in synovial joint function, but this function is diminished when cartilage tissue breaks down in osteoarthritis. Tissue engineering is a promising approach for replacing failed cartilage, as cartilage is a relatively simple tissue with no blood supply and very few biological cells. To imitate the structure of natural cartilage extracellular matrix material, three components must be included: the hydrated ground substance, the charges that contribute to compressive stiffness via electrostatic repulsion, and the nanofibrous collagen network that resists tensile deformation and failure. Here, the nanofiber network is considered, with examination of its fracture behavior in an as-electrospun state and following a mild chemical crosslinking process. Mode III fracture testing was used to quantify the tear toughness of the fibrous mats, and failure behavior was qualitatively examined with scanning electron microscopy. In ongoing work, this nanofibrous structure will be combined with a charged polyelectrolyte hydrogel gel to create a biomimetic cartilage-like material. By using biomimicry to replicate what is present in native cartilage tissue, a superior material can be designed and fabricated for use in tissue repair and replacement.