Ultra-sensitive optimized one-dimensional phononic crystal as a fluidic sensor to enhance the measurement of acetic acid concentration.

The current investigation theoretically presents a one-dimensional phononic crystal (PnC) as a fluidic sensor. The sensor under consideration aims to distinguish the concentration of acetic acid. The primary configuration of the proposed sensor is constructed with lead, epoxy, and a defect layer in the middle of the structure, that is filled with acetic acid (vinegar). As a result of the rise in density and decline in the speed of sound at a 100% concentration of acetic acid in comparison to pure water, the peak frequency of the output has shifted towards lower frequencies. Given that the maximum permissible concentration of acetic acid in water for vinegar is above 30%, sensor simulations were conducted within the concentration range of 25-35% with a step size of 1%. Interestingly, the sensitivity of the sensor exhibits a polynomial change in response to the concentration of acetic acid. Consequently, the highest level of sensitivity, which corresponds to the lowest concentration of vinegar, is recorded as 48.44 × 106 (Hz). The proposed system exhibits a remarkable value of the quality factor of 2802.91. Furthermore, the optimal figure of merit (FOM) is achieved when the concentration is at its lowest, with a value of 94.00. Furthermore, the temperature effects are taken into account for a wide range between 10 and 60 °C. A pronouncing sensitivity is obtained for all temperatures changes and the highest one reached the value of 1.57 × 106 (Hz/°C) at a temperature of 25 °C. Considering the present circumstances, the suggested sensor configuration has the potential to cater to a diverse array of other fluids, specifically their concentration and temperature, thereby offering a broad scope of applications.

Investigating the impact of shear and bulk viscosity on the damping of confined acoustic modes in phononic crystal sensors.

Phononic crystal (PnC) sensors are recognized for their capability to control acoustic wave propagation through periodic structures, presenting considerable potential across various applications. Despite advancements, the effects of fluid viscosity on PnC performance remain intricate and inadequately understood. This study theoretically investigates the influence of shear (dynamic) and bulk viscosity on acoustic wave damping in defective one-dimensional phononic crystal (1D PnC) sensors designed for detecting liquid analytes. Acetic acid with varying viscosities is considered to fill a cavity layer intermediated by a multilayer stack of lead and epoxy. The effects of dynamic and bulk viscosity on the resonance characteristics of the defective mode were analyzed. Numerical results reveal that increased dynamic viscosity leads to substantial broadening and decreased intensity of resonance peaks, accompanied by a shift to higher frequencies due to enhanced elastic wave attenuation and damping. At low dynamic viscosity (η = 0.2 ηd), numerous resonance peaks with varying intensities are observed. However, at higher viscosities (η = 2.0 ηd to η = 10.0 ηd), only one prominent peak appears in the spectrum. The intensity of this resonant peak starts at 98% for η = 2 ηd and decreases to 58.8% as the dynamic viscosity increases to η = 10 ηd. Additionally, the combined effect of dynamic and bulk viscosity introduces further damping, causing a strong shift of the resonance peak to higher frequencies, along with an increase in the full width at half maximum (FWHM) and a decrease in the quality factor (QF). These findings emphasize the necessity of incorporating both shear and bulk viscosity in the design of PnC sensors to enhance their sensitivity and accuracy in practical applications. This theoretical framework provides critical insights for optimizing sensor performance and bridging gaps between theoretical predictions and experimental observations, especially in 1D PnCs, offering potential solutions to challenges in real-world PnC sensor applications.

Fano resonance in one-dimensional quasiperiodic topological phononic crystals towards a stable and high-performance sensing tool.

Phononic crystals (PnCs) emerge as an innovative sensor technology, especially for high-performance sensing applications. This study strives to advance this field by developing new designs of PnC structures that exhibit stability in the face of construction imperfections and deformations, focusing on the evolution of topological PnCs (TPnCs). These designs could be promising to overcome the problem of instability involved in most of the theoretical PnC sensors when they emerge in experimental verification. In particular, the fabrication process of any design could collide with some fluctuations in controlling the size of each component. Thus, Fano resonance is introduced through a one-dimensional (1D) quasiperiodic TPnC. To the best of the author's knowledge, this study is the first to observe Fano modes in liquid cavities through 1D PnCs. Various quasiperiodic PnC designs are employed to detect the temperature of alcohols (specifically propanol) across an extensive temperature range (160-240 °C). The effects of many geometrical parameters on the sensor stability, such as material thicknesses, are studied. Numerical findings demonstrated that the designed quasiperiodic topological PnCs based on Fibonacci sequence of the second order proved superior performance. This sensing tool provides sensitivity, quality factor and figure-of-merit values of 104,533.33 Hz/°C, 223.69 and 0.5221 (/°C), respectively, through temperature detection of propanol in the range of 160-240 °C.

Optical absorption performance of CZTS/ZnO thin film solar cells comprising anti-reflecting coating of texturing configuration.

This paper introduces a novel design of a thin-film solar cell based on CZTS and ZnO composite materials with the help of ITO as the front contact layer. This study primarily focuses on how the cells' optical absorbance at visible wavelengths can be improved. COMSOL Multiphysics is employed as a powerful tool for the investigation of the numerical simulation. The numerical findings showed that the optimum thicknesses of the ITO and ZnO are 80 and 350 nm, respectively. In this regard, with a normal incidence, a wide range of incoming light wavelengths from 450 nm to 800 nm might result in optical absorption of the examined cell of above 0.9. However, this value decreased significantly to reach less than 0.75 when the angle of incidence increased to 50°. To minimize this reduction, on the top surface of the cell, a texture-designed anti-reflective coating designed from a single period of well-known one-dimensional photonic crystals is deposited. The findings demonstrated that the cell's absorption at normal incidence could reach over 0.96 through the overall incident wavelengths. Therefore, CZTS/ZnO thin-film solar cells with an anti-reflecting coating of texturing configuration showed enormous potential for manufacturing effective solar cells.

Hybrid Tamm plasmon resonance excitation towards a simple and efficient biomedical detector of NaI solution.

This work presents a theoretical verification for the detection of Sodium iodide (NaI) solution with different concentrations in the vicinity of Tamm plasmon (TP) resonance. The proposed sensing tool is constituted of {prism/Ag/cavity/(GaN/CaF2)15/air}. The essential foundation of this study is based on the displacement of the TP resonance by varying the concentration of an aqueous solution of sodium iodide (NaI) that fills the cavity layer. The resonant TP dip is shifted downwards the shorter wavelengths with the increment of the Ag layer thickness. Nevertheless, the resonant TP dip is shifted upwards to longer wavelengths with the increment of NaI refractive index/concentration. Also, the sensitivity of the sensing tool decreases with the increment of the NaI refractive index. However, the minimum result is not less than the value of 9913 nm RIU-1 for a concentration of 25%. Finally, the performance of our sensor in the form of the quality factor, detection limit, and figure of merit showed significant improvements in designing a high-performance liquid and biosensor.

Converting Sewage Water into H2 Fuel Gas Using Cu/CuO Nanoporous Photocatalytic Electrodes.

This work reports on H2 fuel generation from sewage water using Cu/CuO nanoporous (NP) electrodes. This is a novel concept for converting contaminated water into H2 fuel. The preparation of Cu/CuO NP was achieved using a simple thermal combustion process of Cu metallic foil at 550 °C for 1 h. The Cu/CuO surface consists of island-like structures, with an inter-distance of 100 nm. Each island has a highly porous surface with a pore diameter of about 250 nm. X-ray diffraction (XRD) confirmed the formation of monoclinic Cu/CuO NP material with a crystallite size of 89 nm. The prepared Cu/CuO photoelectrode was applied for H2 generation from sewage water achieving an incident to photon conversion efficiency (IPCE) of 14.6%. Further, the effects of light intensity and wavelength on the photoelectrode performance were assessed. The current density (Jph) value increased from 2.17 to 4.7 mA·cm-2 upon raising the light power density from 50 to 100 mW·cm-2. Moreover, the enthalpy (ΔH*) and entropy (ΔS*) values of Cu/CuO electrode were determined as 9.519 KJ mol-1 and 180.4 JK-1·mol-1, respectively. The results obtained in the present study are very promising for solving the problem of energy in far regions by converting sewage water to H2 fuel.

Conversion of Sewage Water into H2 Gas Fuel Using Hexagonal Nanosheets of the Polyaniline-Assisted Deposition of PbI2 as a Nanocomposite Photocathode with the Theoretical Qualitative Ab-Initio Calculation of the H2O Splitting.

This study is very promising for providing a renewable enrgy (H2 gas fuel) under the elctrochemical splitting of the wastwater (sewage water). This study has double benefits: hydrogen generation and contaminations removel. This study is carried out on sewage water, third stage treated, from Beni-Suef city, Egypt. Antimony tin oxide (ATO)/polyaniline (PANI)/PbI2 photoelectrode is prepared through the in situ oxidative polymerization of PANI on ATO, then PANI is used as an assistant for PbI2 deposition using the ionic adsorption deposition method. The chemical structural, morphological, electrical, and optical properties of the composite are confirmed using different analytical tools such as X-ray diffreaction (XRD), scanning electron microscope (SEM), transmision electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), and UV-Vis spectroscopy. The prepared PbI2 inside the composite has a crystal size of 33 nm (according to the peak at 12.8°) through the XRD analyses device. SEM and TEM confirm the hexagonal PbI2 sheets embedded on the PANI nanopores surface. Moreover, the bandgap values are enhanced very much after the composite formation, in which the bandgap values for PANI and PANI/PbI2 are 3 and 2.51 eV, respectively. The application of ATO/PANI/PbI2 nanocomposite electrode for sewage splitting and H2 generation is carried out through a three-electrode cell. The measurements carreid out using the electrocehical worksattion under th Xenon lamp (100 mW.cm-2). The produced current density (Jph) is 0.095 mA.cm-2 at 100 mW.cm-2 light illumination. The photoelectrode has high reproducibility and stability, in which and the number of H2 moles is 6 µmole.h-1.cm-1. The photoelectrode response to different monochromatic light, in which the produced Jph decreases from 0.077 to 0.072 mA.cm-2 with decreasing of the wavelengths from 390 to 636 nm, respectively. These values confirms the high response of the ATO/PANI/PbI2 nanocomposite electrode for the light illuminaton and hydrogen genration under broad light region. The thermodynamic parameters: activation energy (Ea), enthalpy (ΔH*), and entropy (ΔS*) values are 7.33 kJ/mol, -4.7 kJ/mol, and 203.3 J/mol.K, respectively. The small values of ΔS* relted to the high sesnivity of the prepared elctrode for the water splitting and then the hydrogen gneration. Finally, a theoretical study was mentioned for calculation geometry, electrochemical, and thermochemistry properties of the polyaniline/PbI2 nanocomposite as compared with that for the polyaniline.

Decay Rates of Plasmonic Elliptical Nanostructures via Effective Medium Theory.

This paper investigates the spontaneous decay rate of elliptical plasmonic nanostructures. The refractive index was analyzed using the effective medium theory (EMT). Then, the polarizability, spontaneous radiative, non-radiative decay rate, and electric field enhancement factor were characterized for the targeted elliptical nanostructures at different aspect ratios. All of the optical analyses were analyzed at different distances between the excited fluorescent coupled atom and the plasmonic nanostructure (down to 100 nm). This work is promising in selecting the optimum elliptical nanostructure according to the required decay rates for optical conversion efficiency control in energy harvesting for solar cells and optical sensing applications.

Efficiency enhancement of CZTSSe solar cells via screening the absorber layer by examining of different possible defects.

This study represents the investigation of earth-abundant and non-toxic CZTSSe absorber materials in kesterite solar cell by using the Finite Element Method (FEM) with (1) electrical, and (2) optical approaches. The simulated results have been validated with the experimental results to define guidelines for boosting the cell performance. For improving the cell efficiency, potential barrier variations in the front contact, and the effect of different lattice defects in the CZTSSe absorber layer have been examined. Controlling the defects and the secondary phases of absorber layer have significant influence on the cell performance improvement. Previous studies have demonstrated that, synthesis of CZTSSe:Na nanocrystals and controlling the S/(S + Se), Cu/(Zn + Sn), and Zn/Sn ratios (stoichiometry) have significant effects on the reduction of trap-assisted recombination (Shockley-Read-Hall recombination model). In this work, a screening-based approach has been employed to study the cell efficiency over a wide range of defect densities. Two categorized defect types including benign defects ([Formula: see text] cm-3 , Nt defines trap density) and harmful defects [Formula: see text] cm-3) in the absorber bandgap in the CZTSSe solar cell, by analyzing their position changes with respect to the electron Fermi level (Efn) and the Valence Band Maximum positions have been identified. It is realized that, the harmful defects are the dominant reason for the low efficiency of the kesterite solar cells, therefore, reducing the number of harmful defects and also total defect densities lead to the power conversion efficiency record of 19.06%. This increment makes the CZTSSe solar cells as a promising candidate for industrial and commercial applications.

Efficiency Enhancement of Perovskite Solar Cells with Plasmonic Nanoparticles: A Simulation Study.

Recently, hybrid organic-inorganic perovskites have been extensively studied due to their promising optical properties with relatively low-cost and simple processing. However, the perovskite solar cells have some low optical absorption in the visible spectrum, especially around the red region. In this paper, an improvement of perovskite solar cell efficiency is studied via simulations through adding plasmonic nanoparticles (NPs) at the rear side of the solar cell. The plasmonic resonance wavelength is selected to be very close to the spectrum range of lower absorption of the perovskite: around 600 nm. Both gold and silver nanoparticles (Au and Ag NPs) are selected to introduce the plasmonic effect with diameters above 40 nm, to get an overlap between the plasmonic resonance spectrum and the requested lower absorption spectrum of the perovskite layer. Simulations show the increase in the short circuit current density (Jsc) as a result of adding Au and Ag NPs, respectively. Enhancement in Jsc is observed as the diameter of both Au and Ag NPs is increased beyond 40 nm. Furthermore, there is a slight increase in the reflection loss as the thickness of the plasmonic nanoparticles at the rear side of the solar cell is increased. A significant decrease in the current loss due to transmission is achieved as the size of the nanoparticles increases. As a comparison, slightly higher enhancement in external quantum efficiency (EQE) can be achieved in case of adding Ag NPs rather than Au NPs.

Lanthanide-Doped Ceria Nanoparticles as Backside Coaters to Improve Silicon Solar Cell Efficiency.

This paper introduces lanthanide-doped ceria nanoparticles as silicon solar cell back-side coaters, showing their influence on the solar cell efficiency. Ceria nanoparticles can be synthesized to have formed oxygen vacancies (O-vacancies), which are associated with converting cerium ions from the Ce4+ state ions to the Ce3+ ones. These O-vacancies follow the rule of improving silicon solar cell conductivity through a hopping mechanism. Besides, under near-ultra violet (near-UV) excitation, the reduced trivalent cerium Ce3+ ions are directly responsible for down converting the un-absorbed UV wavelengths to a resultant green photo-luminescence emission at ~520 nm, which is absorbed through the silicon solar cell’s active layer. Adding lanthanide elements such as Neodymium “Nd” as ceria nanoparticle dopants helps in forming extra oxygen vacancies (O-vacancies), followed by an increase in the number of Ce4+ to Ce3+ ion reductions, thus enhancing the conductivity and photoluminescence down conversion mechanisms. After introducing lanthanide-doped ceria nanoparticles on a silicon solar cell surface, a promising enhancement in the behavior of the solar cell current-voltage curve is observed, and the efficiency is improved by about 25% of its initial value due to the mutual impact of improving both electric conductivity and optical conversions.

Electrospun PVA Polymer Embedded with Ceria Nanoparticles as Silicon Solar Cells Rear Surface Coaters for Efficiency Improvement.

This paper introduces electrospun nanofibers embedded with ceria nanoparticles as silicon solar cells coaters, showing their influence on the solar cells efficiency. Ceria nanoparticles can be synthesized to have formed oxygen vacancies (O-vacancies), which are associated with converting cerium ions from the Ce4+ state ions to the Ce3+ ones. These O-vacancies follow the rule of improving silicon solar cellconductivity through the hopping mechanism. Besides, under violet excitation, the reduced trivalent cerium Ce3+ ions are directly responsible for down-converting the un-absorbed violet or ultra-violet (UV) wavelengths to a resulted green fluorescence emission at ~520 nm. These are absorbed through the silicon solar cells active layer. When electrospun Poly(vinyl alcohol) (PVA) is embedded with ceria nanoparticles on the rear surface of silicon solar cell, a promising enhancement in the behavior of solar cells current⁻voltage (I⁻V) curve is observed. The efficiency has improved by about 24% of its initial value due to the mutual impact of improving both electrical conductivity and optical conversions from the higher surface-to-volume ratio of electrospun nanofibers embedded by ceria nanoparticles. The solar cell efficiency improvement is due to the mutual impact of both optical down-conversion and better electric paths via the used nanocomposite. The added nanostructures coating can utilize part of the transmitted UV or violet spectrum through the cell as optical conversion from violet to the visible region. In addition, the formed active tri-valent states are associated with O-vacancies which can help in a better conductivity of the generated photoelectrons from the cell through the hopping mechanism. The PVA nanofibers host offers a better distribution of ceria nanoparticles and better conductivity paths for the photoelectrons based on the better surface-to-volume ratio of the nanofibers.

Light Management Enhancement for Four-Terminal Perovskite-Silicon Tandem Solar Cells: The Impact of the Optical Properties and Thickness of the Spacer Layer between Sub-Cells.

Mechanical stacking of a thin film perovskite-based solar cell on top of crystalline Si (cSi) solar cell has recently attracted a lot of attention as it is considered a viable route to overcome the limitations of cSi single junction power conversion efficiency. Effective light management is however crucial to minimize reflection or parasitic absorption losses in either the top cell or in the light in-coupling of the transmitted light to the bottom sub-cell. The study here is focused on calculating an optimum performance of a four-terminal mechanically stacked tandem structure by varying the optical property and thickness of the spacer between top and bottom sub-cells. The impact of the nature of the spacer material, with its refractive index and absorption coefficient, as well as the thickness of that layer is used as variables in the optical simulation. The optical simulation is done by using the transfer matrix-method (TMM) on a stack of a semi-transparent perovskite solar cell (top cell) mounted on top of a cSi interdigitated back contact (IBC) solar cell (bottom cell). Two types of perovskite absorber material are considered, with very similar optical properties. The total internal and external short circuit current (Jsc) losses for the semitransparent perovskite top cell as a function of the different optical spacers (material and thickness) are calculated. While selecting the optical spacer materials, Jsc for both silicon (bottom cell) and perovskite (top cell) were considered with the aim to optimize the stack for maximum overall short circuit current. From these simulations, it was found that this optimum in our four-terminal tandem occurred at a thickness of the optical spacer of 160 nm for a material with refractive index n = 1.25. At this optimum, with a combination of selected semi-transparent perovskite top cell, the simulated maximum overall short circuit current (Jsc-combined, max) equals to 34.31 mA/cm². As a result, the four-terminal perovskite/cSi multi-junction solar cell exhibits a power conversion efficiency (PCE) of 25.26%, as the sum of the perovskite top cell PCE = 16.50% and the bottom IBC cSi cell PCE = 8.75%. This accounts for an improvement of more than 2% absolute when compared to the stand-alone IBC cSi solar cell with 23.2% efficiency.