Towards a promising systematic approach to the synthesis of CZTS solar cells.

This study aims to enhance the CZTS device's overall efficiency, the key research area has been identified in this study is to explore the effects of a novel, low-cost, and simplified, deposition method to improve the optoelectronic properties of the buffer layer in the fabrication of CZTS thin film solar cells. Herein, an effective way of addressing this challenge is through adjusting the absorbers' structure by the concept of doping, sensitized CdS thin film by the bi-functional linker, and an environmentally friendly catalytic green agent. The Linker Assisted and Chemical Bath Deposition (LA-CBD) method was introduced as an innovative and effective hybrid sensitization approach. In the one-step synthesis process, Salvia dye, Ag, and 3-Mercaptopropionic acid (MPA) were used. Generally, the results for all samples displayed varying bandgap as achieved between (2.21-2.46) eV, hexagonal structure with considerably decreased strain level, broader grain size, and dramatically enhanced crystalline property. Hence, the rudimentary CdS/CZTS solar cell devices were fabricated for the application of these novel CdS films. Preliminary CZTS thin film solar cell fabrication results in the highest conversion efficiency of 0.266% obtained CdS + Salvia dye, indicating the potential use of the CdS films as a buffer layer for CZTS photovoltaic devices.

Triple-Band Square Split-Ring Resonator Metamaterial Absorber Design with High Effective Medium Ratio for 5G Sub-6 GHz Applications.

This article proposes a square split-ring resonator (SSRR) metamaterial absorber (MMA) for sub-6 GHz application. The unit cell of the MMA was designed and fabricated on commercially available low-cost FR-4 substrate material with a dielectric constant o 4.3. The higher effective medium ratio (EMR) of the designed unit cell shows the compactness of the MMA. The dimension of the unit cell is 9.5 × 9.5 × 1.6 mm3, which consists of two split rings and two arms with outer SSRR. The proposed MMA operates at 2.5 GHz, 4.9 GHz, and 6 GHz frequency bands with a 90% absorption peak and shows a single negative metamaterial property. The E-field, H-field, and surface current are also explored in support of absorption analysis. Moreover, the equivalent circuit model of the proposed MMA is modelled and simulated to validate the resonance behavior of the MMA structure. Finally, the proposed MMA can be used for the specific frequency bands of 5G applications such as signal absorption, crowdsensing, SAR reduction, etc.

An in-depth analysis of nucleation and growth mechanism of CdS thin film synthesized by chemical bath deposition (CBD) technique.

The aim of this study is to acquire a deeper understanding of the response mechanism that is associated with the formation of CdS thin films. We presented an effective and new hybrid sensitisation technique, which involved the 1-step linker between the related chemical bath deposition (CBD) process and the traditional doping method during CBD for synthesising high-quality, CdS thin films. The mechanism for the combined synthesis of the films is also describes. CdS films were electrostatically bonded to soda-lime glass, causing the formation of the intermediate complexes [Cd(NH3)4]2+, which aided in the collision of these complexes with a soda-lime glass slide. In the one-step fabrication technique, 3-Mercaptopropionic Acid (MPA) was employed as a second source of sulphur ions and a linker molecule. Optical studies showed that the bandgap ranged between (2.26-2.52) eV. CdS + MPA films exhibited a uniform distribution of spherical molecules based on their morphological properties. After annealing, this approach significantly altered the electrical characteristics of CdS films. The CdS + MPA films displayed the highest carrier concentration whereas the CdS + Ag + MPA films exhibited the lowest resistivity, with a jump of 3 orders of magnitude.

New systematic study approach of green synthesis CdS thin film via Salvia dye.

In this study, we aimed to increase the knowledge regarding the response mechanisms which were associated with the formation of CdS thin films. CdS thin film remains the most appealing alternative for many researchers, as it has been a capable buffer material for effect in film based polycrystalline solar cells (CdTe, CIGSe, CZTS). The Linker Assisted and Chemical Bath Deposition (LA-CBD) technique, which combines the Linker Assisted (LA) technique and the chemical bath deposition (CBD) method for forming high quality CdS thin film, was presented as an efficient and novel hybrid sensitization technique. CdS films were bound to soda lime with the help of electrostatic forces, which led to the formation of the intermediate complexes [Cd (NH3)4]2+ that helped in the collision of these complexes with a soda lime slide. Salvia dye and as a linker molecule 3-Mercaptopropionic acid (MPA) was used in the one step fabrication technique. Optical results showed that the bandgap varied in the range of (2.50 to 2.17) eV. Morphological properties showed a homogeneous distribution of the particles that aspherical in shape in the CdS + MPA + Salvia dye films. This technique significantly affected on the electrical characterizations of CdS films after the annealing process. The CdS + Ag + MPA + Salvia dye films showed the maximum carrier concentration and minimum resistivity, as 5.64 × 10 18 cm-3 and 0.83 Ω cm respectively.

Metamaterial sensor based on rectangular enclosed adjacent triple circle split ring resonator with good quality factor for microwave sensing application.

In this article, a novel shaped metamaterial sensor is presented for the recognition of various oils, fluids, and chemicals using microwave frequency. The performance of the designed sensor structure has been studied both theoretically and experimentally, and it works well. A new sample holder for convenient operation is created and located just behind the designed structure. The results of this study performed better than those of prior liquids sensing studies. Various designs were explored using the Genetic Algorithm (GA), and it is embedded in the Computer Simulation Technology (CST) microwave studio, to optimize the optimal dimensions of the resonator. The suggested metamaterial sensor has a good-quality factor and sensitivity in both frequency shifting and amplitude changing. The resonance frequency shifted to 100 MHz between olive and corn oils, 70 MHz between sunflower and palm oils, 80 MHz between clean and waste brake fluids, and 90 MHz between benzene and carbon-tetrachloride chemicals. The quality factor of the sensor is 135, sensitivity is 0.56, and the figure of merit is 76 which expresses its efficient performance. Furthermore, the proposed sensor can sensitively distinguish different liquids by using the frequency shifting property. The study was carried out in three stages: dielectric constant (DK) measurement with the N1500A dielectric measurement kit, simulation of the structure, and experimental test study with the vector network analyzer. Since the recommended sensor has high sensitivity, good quality factor, and excellent performance, hence it can be used in chemical, oil, and microfluidic industries for detecting various liquid samples.

Fabrication of Suspended PMMA-Graphene Membrane for High Sensitivity LC-MEMS Pressure Sensor.

The LC-MEMS pressure sensor is an attractive option for an implantable sensor. It senses pressure wirelessly through an LC resonator, eliminating the requirement for electrical wiring or a battery system. However, the sensitivity of LC-MEMS pressure sensors is still comparatively low, especially in biomedical applications, which require a highly-sensitive sensor to measure low-pressure variations. This study presents the microfabrication of an LC wireless MEMS pressure sensor that utilizes a PMMA-Graphene (PMMA/Gr) membrane supported on a silicon trench as the deformable structure. The (PMMA/Gr) membrane was employed to increase the sensor's sensitivity due to its very low elastic modulus making it easy to deform under extremely low pressure. The overall size of the fabricated sensor was limited to 8 mm × 8 mm. The experimental results showed that the capacitance value changed from 1.64 pF to 12.32 pF when the applied pressure varied from 0 to 5 psi. This capacitance variation caused the frequency response to change from 28.74 MHz to 78.76 MHz. The sensor sensitivity was recorded with a value of 193.45 kHz/mmHg and a quality factor of 21. This study concludes that the (PMMA/Gr) membrane-based LC-MEMS pressure sensor has been successfully designed and fabricated and shows good potential in biomedical sensor applications.

WS2: A New Window Layer Material for Solar Cell Application.

Radio frequency (RF) magnetron sputtering was used to deposit tungsten disulfide (WS2) thin films on top of soda lime glass substrates. The deposition power of RF magnetron sputtering varied at 50, 100, 150, 200, and 250 W to investigate the impact on film characteristics and determine the optimized conditions for suitable application in thin-film solar cells. Morphological, structural, and opto-electronic properties of as-grown films were investigated and analyzed for different deposition powers. All the WS2 films exhibited granular morphology and consisted of a rhombohedral phase with a strong preferential orientation toward the (101) crystal plane. Polycrystalline ultra-thin WS2 films with bandgap of 2.2 eV, carrier concentration of 1.01 × 1019 cm-3, and resistivity of 0.135 Ω-cm were successfully achieved at RF deposition power of 200 W. The optimized WS2 thin film was successfully incorporated as a window layer for the first time in CdTe/WS2 solar cell. Initial investigations revealed that the newly incorporated WS2 window layer in CdTe solar cell demonstrated photovoltaic conversion efficiency of 1.2% with Voc of 379 mV, Jsc of 11.5 mA/cm2, and FF of 27.1%. This study paves the way for WS2 thin film as a potential window layer to be used in thin-film solar cells.

The Design, Fabrication, and Testing of an Electromagnetic Micropump with a Matrix-Patterned Magnetic Polymer Composite Actuator Membrane.

A valveless electromagnetic (EM) micropump with a matrix-patterned magnetic polymer composite actuator membrane structure was successfully designed and fabricated. The composite membrane structure is made of polydemethylsiloxane (PDMS) that is mixed with magnetic particles and patterned in matrix blocks. The matrix magnetic composite membrane was fabricated using a soft lithography process and expected to have a compact structure having sufficient magnetic force for membrane deformation and maintained membrane flexibility. The magnetic membrane was integrated with the microfluidic system and functionally tested. The experimental results show that a magnetic composite actuator membrane containing of 6% NdFeB is capable of producing a maximum membrane deflection up to 12.87 µm. The functionality test of the EM actuator for fluid pumping resulted in an extremely low sample injection flow rate of approximately 6.523 nL/min. It was also concluded that there is a correlation between the matrix structure of the actuator membrane and the fluid pumping flow rate. The injection flow rate of the EM micropump can be controlled by adjusting the input power supplied to the EM coil, and this is believed to improve the injection accuracy of the drug dosage and have potential in improving the proficiency of the existing drug delivery system.