Fabrication of inverted organic solar cells on stainless steel substrate with electrodeposited and spin coated ZnO buffer layers

Polymer based organic solar cells (OSCs) are of tremendous interest as suitable candidates for producing clean and renewable energy in recent years. In this study, inverted OSCs on stainless steel (SS) substrate with zinc oxide (ZnO) as the electron selective transport layer (ESTL), are investigated, occupying bulk heterojunction blend of regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) as the active material and poly-(4,3-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the hole transport layer (HTL). The device structure is SS/ZnO/P3HT:PCBM/PEDOT:PSS/Au. ZnO films are prepared by spin coating and electrodeposition techniques, followed by annealing under ambient conditions. The insertion of ZnO layer between the SS substrate and active layer has improved short-circuit current (J sc), open-circuit voltage (V oc), fill factor (FF), and power conversion efficiency (PCE) compared to those of the reference cell without ZnO layer, achieving the highest efficiency of 0.66% for the device with spin coated ZnO from sol–gel technique. This enhancement can be attributed to the effective electron extraction and the increased crystallinity of ZnO after annealing treatments at higher temperatures as further confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses.

Gamma-Ray Attenuation Characteristics of Some Essential Amino Acids for 57Co, 192Ir, 18F, and 116mIn Sources

Purpose: In different tissues of the body, proteins are important parts that are made up of building blocks called amino acids. Considering the wide applications of radioactive sources in industry and medicine, the need to study the attenuation characteristics of amino acids is determined. Materials and Methods: To study the attenuation characteristics of five types of amino acids, MCNPX Monte Carlo code and XMuDat program were used. Linear and mass attenuation coefficients, half and tenth value layers, mean free path, effective atomic and electronic cross-sections, effective atomic numbers and effective electron densities were calculated. 57Co, 192Ir, 18F, and 116mIn gamma sources were considered for this study. To validate the theoretical results, the obtained values were compared with the available experimental data. Results: The difference between the theoretical and experimental results was less than 11%. The results showed that with increasing photon energy, the linear and mass attenuation coefficients and effective atomic and electronic cross-sections decreased, while the half and tenth value layers and mean free path quantities increased. Furthermore, the linear attenuation coefficients, the effective atomic and electronic cross-sections, as well as the effective atomic number values increased with increasing amino acid density, while the effective electron density behaves independently of the amino acid density. Conclusion: The presented theoretical methods produced data similar to experimental results with fair accuracy, so by using these methods, attenuation properties of other amino acids can be obtained over a wide range of energies.

Direct growth of copper(I) oxide nanocubes on graphitic carbon nitrides enhancing aqueous carbon dioxide photoreduction

Semiconductor hybrid structures containing multiple components have been considered an ideal photocatalyst design to generate long-lived charge-separated states. Particularly for the reactions requiring high activation energies, such as a CO2 reduction reaction (CO2RR), the reaction activity is highly susceptible to the catalyst component and morphology. In this study, we selected g-C3N4 and Cu2O as photocatalytic components having bandgaps suitable for CO2RR. Then, we tried to form good electric junctions between two domains by direct growth of Cu on g-C3N4 using a polyol process. The resulting g-C3N4/Cu2O hybrid was employed as photocatalysts in an aqueous medium without hole acceptors. The catalyst exhibited a noticeable activity (5.4 mmol gcat-1h-1) and quantum yield (3.7%) with a nearly quantitative selectivity for CH4 production, superior to any other photocatalysts for CO2RR. The strong coordination of g-C3N4 to the Cu2O surface could form a conductive junction and induce effective electron transfer enforcing the Z-scheme process for CO2RR in high activity and selectivity. This result ensured the importance of junctions and interfaces in the hybrid catalyst structure to exhibit excellent photocatalytic CO2RR performances.

Calculate Effective Atomic Number, Mass and Cross-Section Attenuation Coefficients for Nonanoic Acid by Using Gamma-Ray Sources

The effective atomic number (Z effective), total atomic cross-section (б Total) electron density (N effective) have been Measured depending on the mass attenuation coefficient (μ/ρ). By using Gamma-ray radiation (γ), emitted from sources (57𝐶𝑜, 133𝐵𝑎, 22𝑁𝑎, 137𝐶𝑠, 54𝑀𝑛, 𝑎𝑛𝑑 60𝐶𝑜) with energies from (0.122, 0.356, 0.511, 0.662, 0.84, 1.17, 1.275 𝑎𝑛𝑑 1.33𝑀𝑒𝑉) respectively. using the Sodium Iodide Scintillation Detectors NaI (Tl) at 662 keV and resolution about 8.2% have been measured the mass attenuation coefficients for the sample “Nonanoic acid its common name Pelargonic acid” it’s chemical formula C9H18O2. The data from the mass attenuation coefficient were then employed to study Zeffective, Neffective, and бtotal of the sample. In the presence of gamma-ray energy, it was discovered that the effective atomic number and effective electron densities first drop and they tend to remain nearly constant. The experimental values obtained by Zeffective and Neffective were in excellent agreement with the theoretical values. The theoretical data that is accessible is obtained from XCom, which is available online. The study's findings aid in understanding how (μ/ρ) values change when Zeff and Neff values vary in the case of H, C, and O based biological molecules such as fatty acids.

SIGNIFICANCE OF DX-CENTERS FOR ACOUSTIC INDUCED RECONSTRUCTION PROCESSES OF DEFECTS IN GaN/AlGaN

The experimental results of amplitude effects are compared (from an ultrasonic wave deformation amplitude – a tension τUS) for electron concentration and changes of the lattice parameter on the same sample GaN/Al0.2Ga0.8N/GaN/AlN. It has been experimentally established that at ultrasonic loading (frequency 5–10 MHz, amplitude – towards 2·104 W/m2) there is a nonlinear increase in the effective electron concentration and an increase in the lattice parameter; at the same time, the mobility of electrons decreases and μН(τUS) ~ |τUS|. The energy parameters of the acoustic activation charge carriers process are calculated from the approximation of experimental amplitude changes – Еа ≈ 50 meV and γn(300 K) ≈ 2,5·10-27 m3. The amplitude dependences (increase) of the relative lattice parameter change (ΔС/С) from the tension τUS have been investigated experimentally at different frequencies. The energy of DX-center transition UDX ≈ 108 meV and the activation volume of this transition γDX ≈ 6,6·10-27 m3 are calculated from the approximation of the experimental amplitude changes. The revealed correlation of the magnitude of acoustic induced effects in different experiments allows to build a quantitative energy model of the acoustic action process based on the properties of metastable DX centers. It is shown that the acoustic induced process occurs due to the dimensional displacement of the DX-center atom (a background impurity of silicon atoms) from the non-central position to the centrally symmetric one; herewith DX-center is ionized, one goes into the d0-state. It is believed that the changes are most likely to occur near penetrating dislocations in the barrier layer Al0.2Ga0.8N – acoustic modulated oscillations of the distance between the possible positions of the donor atom lead to a decrease in the barrier to the displacement of the defect.

Tailoring linear and nonlinear surface plasmon response in borophene nanostructure

A newly reported 2D material “borophene” provides a novel building block for nanoscale materials and devices. In this work, the linear and nonlinear plasmonic response of electric dipole moment in the metallic borophene is theoretically investigated. In our proposed model, the borophene nanostructure is deposited on the top of the dielectric layer sandwiched with the silver layer acting as a mirror. It was found that the scattering at the scattering peak originates mainly from the exciting total electric dipole. Our calculations demonstrated that scattering in the proposed model can be tuned well with carrier relaxation time, effective electron mass, and free carrier density. The strongly localized fundamental field induces the desired increase of second harmonic wave, which is discussed in detail by introducing the second-order nonlinear source. In addition, the evolution of the lifetime of linear and nonlinear plasmonic modes is also investigated which helps us to study the underlying mechanism of micro process in the borophene plasmonic-photonic interaction. The manipulation of plasmonic behavior and lifetime evolution makes the borophene an excellent platform for tunable plasmonic-photonic devices.

Neutron/gamma radiation shielding characteristics and physical properties of (97.3–x)Pb–xCd–2.7Ag alloys for nuclear radiation applications

In this work, the shielding performance of (97.3–x)Pb–xCd–2.7Ag (x=10, 18, and 30) ternary alloys against neutrons and gamma rays has been investigated. The microstructure, thermal and mechanical properties of the ternary alloys were examined. The total mass attenuation coefficients, μ⁄ρ, for prepared alloys were determined at 662, 1173, and 1332 keV photon energies using NaI (Tl) scintillation detector. The theoretical values of μ⁄ρ were calculated using WinXCom program depending on the mixture rule. The estimated values were compared with the measured values for all investigated alloys. Atomic cross-section, σa, electronic cross-section, σe, effective atomic number, Zeff, effective electron number, Neff, and GP fitting parameters (b, c, a, Xk, and d) were determined. The exposure buildup factor, EBF, have been also calculated. Fast neutron attenuation for the prepared samples have been investigated via the macroscopic effective removal cross-section (∑_R) calculation. Also, thermal neutron attenuation has been evaluated via neutron scattering calculator. The results show that the alloys containing 10 and 30% Cd compromise between superior tensile strength and Young modulus, while the pasty range, heat of fusion and ductility decreased with increasing Cd content. Moreover, the prepared ternary alloys have a high attenuation ability for gamma rays as the standard Pb. The increase of Cd ratio also significantly enhances the thermal neutron attenuation by amazing way along with the increase in the attenuation rate of fast neutrons.

Evaluation of Gamma Radiation Properties of Four Types of Surgical Stainless Steel in the Energy Range of 17.50–25.29 keV

In this study, the gamma radiation properties of four types of surgical-grade stainless steel (304, 304L, 316 and 316L) were investigated. The effective atomic number Zeff, effective electron density Neff and half-value layer (HVL) of four types of surgical-grade stainless steel were determined via the mass attenuation coefficient (μ/ρ). The μ/ρ coefficients were determined experimentally using an X-ray fluorescence (XRF) technique and theoretically via the WinXCOM program. The Kα1 of XRF photons in the energy range between 17.50 and 25.29 keV was used from pure metal plates of molybdenum (Mo), palladium (Pd), silver (Ag) and tin (Sn). A comparison between the experimental and theoretical values of μ/ρ revealed that the experimental values were lower than the theoretical calculations. The relative differences between the theoretical and experimental values were found to decrease with increasing photon energy. The lowest percentage difference between the experimental and theoretical values of μ/ρ was between −6.17% and −9.76% and was obtained at a photon energy of 25.29 keV. Sample 316L showed the highest value of μ/ρ at the energies 21.20, 22.19 and 25.29 keV. In addition, the measured results of Zeff and Neff for all samples behaved similarly in the given energy range and were found to be in good agreement with the calculations. The equivalent atomic number (Zeff) of the investigated stainless-steel samples was calculated using the interpolation method to compare the samples at the same source energy. The 316L stainless steel had higher values of μ/ρ, Zeff and Zeq and lower values of HVL compared with the other samples. Therefore, it is concluded that the 316L sample is more effective in absorbing gamma radiation.

The Use of Nanostructured Calcium Silicate in Solar Cells

<p>Nanostructured calcium silicate (NCaSil) had previously been found to be photoactive and mildly semiconducting. Its use in solar cells was investigated in this project. Many different types of solar cells exist. Most common on the market are silicon-based cells, which generate charge separation through electric fields at p/n junctions. Over the last decade, dye-sensitised solar cells (DSSCs) have been heavily researched. DSSCs depend on effective electron/hole separation at the dye and efficient transfer to the electron- and hole-conducting materials. An older and little-researched form of cells is the photogalvanic cell, of which there are two forms. One contains a semiconducting material, whereas the other comprises of either one or two redox couples, in which at least one species is photoactive. An example of the latter form of cell is the odide/triiodide redox couple, which is commonly the electrolyte of choice in DSSCs and semiconductor-containing photogalvanic cells. This project predominantly investigated the use of NCaSil in conjunction with the iodide/triiodide redox couple and its use in solar cells. The project ascertained that, when used with the iodide/triiodide, the NCaSil did not act as a semiconducting material (either as in a DSSC or semiconductor photogalvanic cell). Rather iodide/triiodide's photogalvanic process dominated the cell, despite the presence of NCaSil. Furthermore, the addition of the stable NCaSils to the iodide/triiodide (with 5 wt% CaCl2) created "soggy sand electrolytes". These electrolytes showed increased conductivities, despite their higher viscosities, due to a synergistic effect. Soggy sand electrolytes show great promise in the development of more solid-like DSSCs. Furthermore, the project observed that the performance of NCaSil cells was maximized with a 70 wt% ethanol (30 wt% water) solvated electrolyte, with 1.5 wt% CaCl2 added to this electrolyte (or 5 wt % CaCl2 in the water content). When used long-term in conjunction with Reinforced NCaSil, a gel was formed, which showed promising activity. This activity was attributed to the interaction of surface-bound Ca2+ to iodine. Similar gels formed from vanadium- and cerium-treated NCaSil also showed great cell performance. Cell performance was further enhanced by backing the cell with a reflective or light scattering material, such as Teflon tape.</p>