Assessing soil pollution concerns in proximity to Fence-type solar photovoltaic system installations.

This study conducted in the Kyungpook National University Eco-friendly Agriculture Research Centre between 2022 and 2023 investigates the environmental implications of fence-type solar photovoltaic (PV) systems in diverse agricultural settings. Despite the increasing adoption of solar energy for climate change mitigation, there is a noticeable gap in research regarding the potential environmental impact of these specific PV systems. Focusing on heavy metal concentrations, including Cadmium (Cd), Copper (Cu), Arsenic (As), Mercury (Hg), Lead (Pb), Hexavalent Chromium (Cr+6), Zinc (Zn), and Nickel (Ni), across distinct fields, the study reveals significant fluctuations. Notably, the Rice Field experienced a substantial increase in Cd levels from 0.47 mg/kg in 2022 to 1.55 mg/kg in 2023, while Cu and Pb concentrations decreased to acceptable levels in 2023. The findings underscore the dynamic nature of heavy metal concentrations, emphasizing the importance of continuous soil quality monitoring to prevent contamination. This research provides valuable insights into the impact of fence-type solar PV system installations on agricultural soil quality, emphasizing the urgent need to secure these ecosystems through vigilant monitoring and environmental management practices.

A Brief Review of Transparent Conducting Oxides (TCO): The Influence of Different Deposition Techniques on the Efficiency of Solar Cells.

Global-warming-induced climate changes and socioeconomic issues increasingly stimulate reviews of renewable energy. Among energy-generation devices, solar cells are often considered as renewable sources of energy. Lately, transparent conducting oxides (TCOs) are playing a significant role as back/front contact electrodes in silicon heterojunction solar cells (SHJ SCs). In particular, the optimized Sn-doped In2O3 (ITO) has served as a capable TCO material to improve the efficiency of SHJ SCs, due to excellent physicochemical properties such as high transmittance, electrical conductivity, mobility, bandgap, and a low refractive index. The doped-ITO thin films had promising characteristics and helped in promoting the efficiency of SHJ SCs. Further, SHJ technology, together with an interdigitated back contact structure, achieved an outstanding efficiency of 26.7%. The present article discusses the deposition of TCO films by various techniques, parameters affecting TCO properties, characteristics of doped and undoped TCO materials, and their influence on SHJ SC efficiency, based on a review of ongoing research and development activities.

Experimental and Statistical Approach to Detect the Corrosion Rate and Influencing Profiles for Enhancing Corrosion Rate of High-Voltage Insulator Materials.

The influence of temperature, pollutant, and pH on the local corrosion rate of insulators installed in industrial, marine, and rural installation sites is investigated based on experimental and statistical investigations. The tensile load test confirms that corroded insulator specimens collected from industrial sites aged more than 10 years represent a minimum fracture load, 19,892 lbs. It was further observed that more than 91.24% and 64.62% corroded insulator specimens suffered from shell break and pin detachment, respectively. The microstructural and XRF analysis reveal that insulator specimens collected from industrial sites (age > 10 years), represented the highest wt% of O (19.2) and lowest wt% of Zn (0.34) among industrial, marine, and rural installation sites. The 3D stationery mechanical simulation reveals that insulator specimens aged > 10 years experienced maximum stress (600 MPa) in the pin-cement interface. Using full two-level factorial designs, temperature, concentration of pollutants, and pH were found significant factors for corrosion rate. The immersion test results further confirm the above-mentioned factors significant for the dissolution behavior of galvanized coating of insulator pin. Following immersion test results, the industrial region shows the highest corrosion rate (5.58-12 µm/year) among all installation sites.

Fabrication of Hierarchical Patterned Surfaces Using a Functionalized CeO2-EPDM Composite for Crevice Corrosion Prevention on High-Voltage Insulators.

Crevice corrosion accounts for 62% of the recorded breakdown of insulators utilized in transmission lines, which may interfere with the reliability of power utilities. To address these challenges, sustainable and resilient slippery lubricant-infused porous surfaces (SLIPS) are developed on insulators to prevent electrochemically/biochemically induced crevice corrosion especially occurring in tropical and coastal environments. The conventional way of developing SLIPS by chemical and physical etching might interfere with the mechanical stability of insulators composed of pin (galvanized steel), cement, and shell (porcelain). The current study proposes a noble concept of developing hierarchical patterned textured surfaces on insulators to fabricate a resilient SLIPS coating without physical/chemical etching. The proposed coating exhibits 99% antiadhesion performance against a mixed culture of bacterial strains, superior hydrophobicity (contact angle: 160°, contact angle hysteresis: 4°), and crevice corrosion resistance performance at elevated temperatures (25-75 °C) and humidity. This study could facilitate a new route for the development of sustainable and highly reliable SLIPS coatings in the future.

Crack resistance of a noble green hydrophobic antimicrobial sealing coating film against environmental corrosion applied on the steel-cement interface for power insulators.

Due to their great load-bearing capabilities, steel-cement interface structures are commonly employed in construction projects, and power utilities including electric insulators. The service life of the steel-cement interface is always decreasing owing to fracture propagation in the cement helped by steel corrosion. In this paper, a noble crack-resistant solution for steel-cement interfaces utilized in hostile outdoor environments is proposed. A Ce-rich, homogeneous, and thick hydrophobic sealing coating (HSC) is developed on the steel-cement interface after 60 minutes of immersion in a 60 000 ppm CeCl3·7H2O sealing coating solution. The specimens treated with optimized HSC film demonstrate fissure filling, lowest corrosion current (I corr) 2.3 × 10-7 A cm-2, maximum hardness (109 Hv), oxide-jacking resistance (40 years), hydrophobic characteristics, carbonation resistance, and bacterial corrosion resistance, resulting in a crack-free steel-cement interface. This work will pave the way for a new branch of environmentally acceptable coatings for the construction and power industries.

Novel synthesis of a self-healing Ce based eco-friendly sealing coating to mitigate corrosion in insulators installed in industrial regions.

Overcoming hardware corrosion for high voltage insulators is a vital issue to prevent the sudden breakdown of insulators. The development of an efficient, economical, and eco-friendly anti-corrosion coating is essential to replace existing carcinogenic and toxic silicone-based coatings used by insulator industries. This article investigates the anticorrosion performance of a novel cerium-based sealing coating for insulator pins installed in highly corrosive (35 µm per year) industrial regions. The coating bath parameters were optimized to improve the self-healing, thermal, crack, and corrosion resistance of the coating. After immersion in a 60 000 ppm CeCl3·7H2O sealing coating bath for 60 minutes, a Ce-rich and dense protective coating (24.4 µm) is formed on the pin surface. The specimens immersed in a 60 000 ppm Ce sealing coating bath for 60 minutes show the lowest I corr. The anticorrosion performance is enhanced by 95% for coated pins than non-coated ones. The electrochemical experiments, macroscopic and microscopic structural analysis confirm the anticorrosion performance of Ce-based sealing coatings for high voltage insulator pins. This work will facilitate a new branch of eco-friendly coatings for insulator and power industries.

Application of noble cerium-based anti-corrosion sealing coating approach applied on electrical insulators installed in industrial regions.

Pin corrosion is a critical issue that causes premature rupture of high-voltage insulators. The development of efficient, defect-free, thermal resistive, hard, economical and environment-friendly sealing coating system is required to replace the current polymer-based highly toxic coatings for insulators. This study investigates the suitability of noble cerium (Ce)-based sealing coating film for use as an anti-corrosion coating for insulator pins installed in low-pH and highly corrosive sites. The coating bath parameters are optimized for the formation of a high-performance Ce-based protective sealing coating. After immersion in a 60 000 ppm CeCl3.7H2O sealing coating bath for 60 min, a Ce-rich and dense protective coating (24 µm) is formed on the pin surface. The life expectancy of the coated pin is 2.5 times higher than that of the non-coated galvanized pins. Electrochemical experiments and microstructural analysis demonstrate that Ce-based protective layers are suitable for long-term protection of high-voltage insulator pins in low-pH and high-corrosion-rate sites. We believe that this work would pave the way of developing ecofriendly anti-corrosion coatings for electric insulators and power industries.

Corrosion Inhibition of Mild Steel in Hydrochloric Acid Environments Containing Sonneratia caseolaris Leaf Extract.

Sonneratia caseolaris leaf extract was characterized for its mitigation of the electrochemical corrosion of steel in naturally aerated hydrochloric acid environments by electrochemical methods and surface analysis. The presence of S. caseolaris leaf extract (SCLE) in the hydrochloric acid medium ameliorated the corrosion resistance of steel via the adsorption of SCLE species to form a barrier layer. The improved inhibition effectiveness was demonstrated to be independent of the SCLE concentration and the corrosive environment. The highest inhibition performance of approximately 98% was reached for steel in a 1 M HCl medium containing 2500 ppm SCLE. The performance significantly decreased with a decrease in the HCl concentration from 1.00 to 0.01 M with the same SCLE concentration. In addition, severe corrosion occurred on the uninhibited steel surface but was significantly reduced on the inhibited steel surface. The analyzed results also indicated the existence of electronegative functional groups in SCLE, which could promote the adsorption process for the self-formation of the barrier layer on the steel surface. The work reported herein suggested a powerful strategy to mitigate electrochemical corrosion by adding an effective new inhibitor to achieve a green inhibitor system.

Over 30% efficiency bifacial 4-terminal perovskite-heterojunction silicon tandem solar cells with spectral albedo.

We developed and designed a bifacial four-terminal perovskite (PVK)/crystalline silicon (c-Si) heterojunction (HJ) tandem solar cell configuration albedo reflection in which the c-Si HJ bottom sub-cell absorbs the solar spectrum from both the front and rear sides (reflected light from the background such as green grass, white sand, red brick, roofing shingle, snow, etc.). Using the albedo reflection and the subsequent short-circuit current density, the conversion efficiency of the PVK-filtered c-Si HJ bottom sub-cell was improved regardless of the PVK top sub-cell properties. This approach achieved a conversion efficiency exceeding 30%, which is higher than those of both the top and bottom sub-cells. Notably, this efficiency is also greater than the Schockley-Quiesser limit of the c-Si solar cell (approximately 29.43%). The proposed approach has the potential to lower industrial solar cell production costs in the near future.

High mobility field-effect transistors based on MoS2crystals grown by the flux method.

Two-dimensional (2D) molybdenum disulphide (MoS2) transition metal dichalcogenides (TMDs) have great potential for use in optical and electronic device applications; however, the performance of MoS2is limited by its crystal quality, which serves as a measure of the defects and grain boundaries in the grown material. Therefore, the high-quality growth of MoS2crystals continues to be a critical issue. In this context, we propose the formation of high-quality MoS2crystals via the flux method. The resulting electrical properties demonstrate the significant impact of crystal morphology on the performance of MoS2field-effect transistors. MoS2made with a relatively higher concentration of sulphur (a molar ratio of 2.2) and at a cooling rate of 2.5 °C h-1yielded good quality and optimally sized crystals. The room-temperature and low-temperature (77 K) electrical transport properties of MoS2field-effect transistors (FETs) were studied in detail, with and without the use of a hexagonal boron nitride (h-BN) dielectric to address the mobility degradation issue due to scattering at the SiO2/2D material interface. A maximum field-effect mobility of 113 cm2V-1s-1was achieved at 77 K for the MoS2/h-BN FET following high-quality crystal formation by the flux method. Our results confirm the achievement of large-scale high-quality crystal growth with reduced defect density using the flux method and are key to achieving higher mobility in MoS2FET devices in parallel with commercially accessible MoS2crystals.

Design of High-Power and High-Density Photovoltaic Modules Based on a Shingled Cell String.

Building-integrated photovoltaic (BIPV) arrays, which are installed on the roofs of buildings as part of urban solar power generation, have created a demand for high-power and high-density photovoltaic (PV) modules to produce high-output power in a limited area. In this paper, a high-power PV module using a shingles technology is designed. When the vertical and horizontal dimensions of the module were 201.78 cm × 96.75 cm in the same area as that of the conventional PV module, the number of cell strips reached 390. When six 65-interconnection shingled strings were connected in series, the output power of 367.8 W was achieved. Compared with a conventional PV module of the same area, the output power was 8% greater.

Influence of Ultra-Thin Ge3N4 Passivation Layer on Structural, Interfacial, and Electrical Properties of HfO2/Ge Metal-Oxide-Semiconductor Devices.

We report the effects of the nitride passivation layer on the structural, electrical, and interfacial properties of Ge metal-oxide-semiconductor (MOS) devices with a hafnium oxide (HfO2) gate dielectric layer deposited on p-type 〈100〉 Ge substrates. X-ray photoelectron spectroscopy analysis confirmed the chemical states and formation of HfO2/Ge3N4 on Ge. The interfacial quality and thickness of the layers grown on Ge were confirmed by high-resolution transmission electron microscopy. In addition, the effects of post-deposition annealing (PDA) on the HfO2/Ge3N4/Ge and HfO2/Ge samples at 400 °C in an (FG+O2) ambient atmosphere for 30 min were studied. After PDA, the HfO2/Ge3N4/Ge MOS device showed a higher dielectric constant (k) of ~21.48 and accumulation capacitance of 1.2 nF, smaller equivalent oxide thickness (EOT) of 1.2 nm, and lower interface trap density (Dit) of 4.9×1011 cm-2 eV-1 and oxide charges (Qeff) of 7.8×1012 cm-2 than the non-annealed sample. The I-V analysis showed that the gate leakage current density of the HfO2/Ge3N4/Ge sample (0.3-1 nA cm-2 at Vg = 1 V) was half of that of the HfO2/Ge sample. Moreover, the barrier heights of the samples were extracted from the Fowler-Nordheim plots. These results indicated that nitride passivation is crucial to improving the structural, interfacial, and electrical properties of Ge-based MOS devices.

High-Efficiency Photo-Generated Charges of ZnO/TiO2 Heterojunction Thin Films for Photocatalytic and Antibacterial Performance.

Forming heterostructures based on hybrid photocatalysts has been considered as one of the most effective techniques for improving the photocatalytic efficacy of semiconductor photocatalysts. To address this issue, this article describes ZnO/TiO2 heterojunction thin films that were produced via the direct current reaction magnetron sputtering technique and with varying thickness of TiO2 coating. The structural, morphological, and optical features were thoroughly characterized by X-ray diffraction, scanning electron microscope, photoluminescence, and ultra-violet-visible transmission spectra. The photocatalytic and antibacterial ability were assessed by the photo-degradation of methyl orange (MO) aqueous solution and count method of E. coli bacteria. The results demonstrated that the photocatalytic and antimicrobial efficacy of the ZnO/TiO2 heterojunction was found to vary depending on the morphology of the TiO2 layer. In addition, their photocatalytic (91% MO degradation within 150 min) and antimicrobial efficacy (92.7% antibacterial efficiency within 90 min) were higher than the efficiency of either material alone. This could can be ascribed to the photogenerated charge carrier efficiency and hierarchical nanostructure with a large surface area. The mechanism for the improved photocatalytic performance has been discussed in detail.

Analysis of Cement Deterioration in Outdoor High-Voltage Insulator.

Suspension type porcelain insulators used in overhead transmission lines comprise metal, ceramic, and cement. The deterioration of cement can lead to mechanical separation. For the degradation analysis, varied sizes of pores ranging from a few µm (capillary pores) to tens to hundreds of mm (detectable by naked eyes) were considered. Cracks that were hard to view with naked eyes were identified by staining with a fuchsine solution. The hydrogen ion concentration and pH value indicate the extent to which the cement is deteriorated. The longer the cement is used, the lower its pH value. High mechanical strength is considered an important advantage of porcelain insulators, and it may decline, if the cement is used for a longer period of time. Water ingress may also occur, resulting in expansion, due to the rehydration of the cement. The process and mechanism of expansion of cement, due to infiltration of water were described. As a method of analysis, a universal indicator was employed to evaluate the pH changes in cement. It was observed that the pH value was 12-13 for new products. However, for products that were used for 52 years, the pH value was under 7, which indicated an acidic tendency, due to deterioration.

Electrical and Structural Characteristics of Excimer Laser-Crystallized Polycrystalline Si1-xGex Thin-Film Transistors.

We investigated the characteristics of excimer laser-annealed polycrystalline silicon-germanium (poly-Si1-xGex) thin film and thin-film transistor (TFT). The Ge concentration was increased from 0% to 12.3% using a SiH4 and GeH4 gas mixture, and a Si1-xGex thin film was crystallized using different excimer laser densities. We found that the optimum energy density to obtain maximum grain size depends on the Ge content in the poly-Si1-xGex thin film; we also confirmed that the grain size of the poly-Si1-xGex thin film is more sensitive to energy density than the poly-Si thin film. The maximum grain size of the poly-Si1-xGex film was 387.3 nm for a Ge content of 5.1% at the energy density of 420 mJ/cm2. Poly-Si1-xGex TFT with different Ge concentrations was fabricated, and their structural characteristics were analyzed using Raman spectroscopy and atomic force microscopy. The results showed that, as the Ge concentration increased, the electrical characteristics, such as on current and sub-threshold swing, were deteriorated. The electrical characteristics were simulated by varying the density of states in the poly-Si1-xGex. From this density of states (DOS), the defect state distribution connected with Ge concentration could be identified and used as the basic starting point for further analyses of the poly-Si1-xGex TFTs.

The Characteristics of Transparent Non-Volatile Memory Devices Employing Si-Rich SiOX as a Charge Trapping Layer and Indium-Tin-Zinc-Oxide.

We fabricated the transparent non-volatile memory (NVM) of a bottom gate thin film transistor (TFT) for the integrated logic devices of display applications. The NVM TFT utilized indium-tin-zinc-oxide (ITZO) as an active channel layer and multi-oxide structure of SiO2 (blocking layer)/Si-rich SiOX (charge trapping layer)/SiOXNY (tunneling layer) as a gate insulator. The insulators were deposited using inductive coupled plasma chemical vapor deposition, and during the deposition, the trap states of the Si-rich SiOx charge trapping layer could be controlled to widen the memory window with the gas ratio (GR) of SiH4:N2O, which was confirmed by fourier transform infrared spectroscopy (FT-IR). We fabricated the metal-insulator-silicon (MIS) capacitors of the insulator structures on n-type Si substrate and demonstrated that the hysteresis capacitive curves of the MIS capacitors were a function of sweep voltage and trap density (or GR). At the GR6 (SiH4:N2O = 30:5), the MIS capacitor exhibited the widest memory window; the flat band voltage (ΔVFB) shifts of 4.45 V was obtained at the sweep voltage of ±11 V for 10 s, and it was expected to maintain ~71% of the initial value after 10 years. Using the Si-rich SiOX charge trapping layer deposited at the GR6 condition, we fabricated a bottom gate ITZO NVM TFT showing excellent drain current to gate voltage transfer characteristics. The field-effect mobility of 27.2 cm2/Vs, threshold voltage of 0.15 V, subthreshold swing of 0.17 V/dec, and on/off current ratio of 7.57 × 107 were obtained at the initial sweep of the devices. As an NVM, ΔVFB was shifted by 2.08 V in the programing mode with a positive gate voltage pulse of 11 V and 1 µs. The ΔVFB was returned to the pristine condition with a negative voltage pulse of -1 V and 1 µs under a 400-700 nm light illumination of ~10 mWcm-2 in erasing mode, when the light excites the electrons to escape from the charge trapping layer. Using this operation condition, ~90% (1.87 V) of initial ΔVFB (2.08 V) was expected to be retained over 10 years. The developed transparent NVM using Si-rich SiOx and ITZO can be a promising candidate for future display devices integrating logic devices on panels.

Improvement of Electrical Performance in P-Channel LTPS Thin-Film Transistor with a-Si:H Surface Passivation.

We report the effects of surface passivation by depositing a hydrogenated amorphous silicon (a-Si:H) layer on the electrical characteristics of low temperature polycrystalline silicon thin film transistors (LTPS TFTs). The intrinsic a-Si:H layer was optimized by hydrogen dilution and its structural and electrical characteristics were investigated. The a-Si:H layer in the transition region between a-Si:H and µc-Si:H resulted in superior device characteristics. Using a-Si:H passivation layer, the field-effect mobility of the LTPS TFT was increased by 78.4% compared with conventional LTPS TFT. Moreover, the leakage current measured at VGS of 5 V was suppressed because the defect sites at the poly-Si grain boundaries were well passivated. Our passivation layer, which allows thorough control of the crystallinity and passivation-quality, should be considered as a candidate for high performance LTPS TFTs.

Insight into the adsorption mechanisms of methylene blue and chromium(iii) from aqueous solution onto pomelo fruit peel.

In this study, the biosorption mechanisms of methylene blue (MB) and Cr(iii) onto pomelo peel collected from our local fruits are investigated by combining experimental analysis with ab initio simulations. Factors that affect the adsorption such as pH, adsorption time, adsorbent dosage and initial adsorbate concentration, are fully considered. Five isotherm models-Langmuir, Freundlich, Sips, Temkin, and Dubinin-Radushkevich-are employed to estimate the capacity of pomelo peel adsorption, whereas four kinetic models-pseudo-first-order, pseudo-second-order, Elovich and intra-diffusion models-are also used to investigate the mechanisms of the uptake of MB and Cr(iii) onto the pomelo fruit peel. The maximum biosorption capacities calculated from the Langmuir models for MB and Cr(iii) at 303 K are, 218.5 mg g-1 and 11.3 mg g-1, respectively. In particular, by combining, for the first time, the experimental FT-IR spectra with those obtained from ab initio calculations, we are able to demonstrate that the primary adsorption mechanisms of the uptake of MB onto pomelo fruit peel are electrostatic attraction and hydrogen-bond formations, whereas the adsorption mechanisms for Cr(iii) are electrostatic attraction and n-d interactions.

Electron Beam Irradiated Al Doped ZnO Thin Films as Efficient Tunnel Recombination Junction for Hydrogenated Amorphous Silicon/Cu(In,Ga)Se2 Tandem Solar Cells.

A tunnel recombination junction (TRJ) layer for hydrogenated amorphous silicon (a-Si:H)/ Cu(In,Ga)Se2 (CIGS) tandem solar cells is investigated. An Al-doped zinc oxide (AZO) thin film is applied to the TRJ, and the influence of electron beam (e-beam) irradiation on defects along the TRJ is investigated. The AZO thin films are prepared using radio frequency (RF) sputtering and the e-beam is irradiated at 200 W RF power and 2 keV DC power for 5 min. In the e-beam irradiated AZO thin film, the number of oxygen vacancies and Zn interstitials increases, which in turn strengthens the effect of defect-enhanced tunnel recombination.

HF etched glass substrates for improved thin-film solar cells.

A hemisphere-array textured glass substrate was fabricated for the development of an improved thin-film (TF) silicon solar cell. The HF-H2SO4-etchant system influenced the light path owing to the formation of the strong fluorine-containing HSO3F acid. In particular, the etching system of the various HF concentration with a constant H2SO4 solution is related to make an improvement of optical transmittance and light trapping structure without a uniform pattern. According to the specular transmittance measurements, the haze ratio was maintained for the glass sample etched with 35% HF in the longer-wavelength region. The proposed substrate was implemented in a TF-Si solar cell, and an improved conversion efficiency was observed according to the short-circuit current density owing to the increase in the haze ratio. This morphology, therefore, induces more scattering at the front side of the cell and leads to an improvement of the open circuit voltage gain for the HF 25% cell. It will be helpful to understand the application of thin film solar cell based on the HF-H2SO4 etching system for the readers.