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In this study, low-cost laser marker ablation of vanadium-coated glass was adopted to prepare self-cleaning, anti-reflective, and anti-fog micro-nano structures on its surface. The surface had a hierarchical micro-nano structure composed of a quasi-periodic microstructure and ∼100 nm-sized worm-like clusters interspersed with dispersed nanoparticles. The solar spectrum (AM 1.5) weighted average transmission of treated glass was enhanced by 3.87% over control glass in the wavelength range of 400–1100 nm. Importantly, the water contact angle of the laser-treated samples achieved and maintained 0° for a duration of 25 days, and the laser-treated samples achieved and maintained excellent anti-fog performance for 150 days. The antifog performance degraded substantially afterward, though was still noticeable compared to the reference even after 428 days of storage in the laboratory. Furthermore, co-achievement of exceptional self-cleaning anti-fog performance and broadband transmission enhancement through laser treatment of glass has rarely been previously reported. [ABSTRACT FROM AUTHOR]

This article discusses a new fabrication process for colloidal silicon quantum dots (SiQDs) that allows for the tuning of their luminescence color from red to green. The process involves low-temperature thermal cracking of electrochemically prepared meso-porous silicon flakes in a mixture of 10-undecen-1-ol and aqueous hydrogen fluoride solution. The size of the SiQDs and their luminescence color can be controlled by adjusting the content of hydrogen fluoride. The article also explores the properties and potential applications of SiQDs in various fields, such as photovoltaic devices, light emitting devices, bio-imaging, and sensing. The document discusses the size-dependent radiative recombination processes of SiQDs, including factors that can affect their photoluminescence properties. It also explains the formation mechanisms of SiQDs and how they can result in different photoluminescence colors and peak wavelengths. The document concludes by discussing the relationship between the size of SiQDs and their photoluminescence peak energies, as well as the effect of surface passivation on quantum confinement. The article presents a novel method for producing SiQDs with tunable emission colors and suggests potential applications for SiQD devices. [Extracted from the article]

We have studied the aging-induced degradation effect and the related mechanism of blue and ultraviolet (UV) laser diodes (LDs). First of all, the F parameter value, leakage current, and yellow luminescence intensity of LDs all increase after 24 h of the aging process, indicating that one of the reasons for the degradation of UV LDs may be the increase of the non-radiative recombination center in the material. Second, irreversible damage may be found on the front cavity surface of the UV and blue LDs. Due to the large UV photon energy, water molecules in the environment atmosphere are ionized to form OH− ions, which combine with dust in air to form SiO2 sediments and then attach to the front cavity surface. In addition, a large photon energy may cause damage to the anti-reflection film on the front cavity surface and lead to a too-high local temperature near the cavity surface, resulting in molten Ga droplets. Both sediment and the precipitation of molten GaN on the cavity surface will directly affect the function of the front cavity surface and the output power of the LD. In order to improve the reliability of the GaN-based UV LDs, it is necessary to reduce the density of material defects, select more stable coating materials on cavity facets, and improve the sealing property of the device package. [ABSTRACT FROM AUTHOR]

Multifunctional thin films are becoming extremely popular in many technological fields. An increase in their functionality can be achieved by the creation of nanocomposite structures. This study represents novel thin composite coatings with a horizontally oriented single-walled carbon nanotube (SWCNT) filler inside a silicon oxynitride (SiO x N y) matrix obtained by (i) low-temperature thermal curing or by (ii) UV radiation-induced curing. The SiO x N y /SWCNT composite structures were prepared by simple dry transfer of a SWCNT film into a perhydropolysilazane (PHPS) polymer matrix film deposited by the spin-coating technique followed by curing. The structural, morphological, and optical properties of the SiO x N y /SWCNT composite films were studied using HR-SEM/EDX, ATR-FTIR, and UV–Vis spectroscopy. It was found that SWCNT films were uniformly transferred into the PHPS matrix, maintaining their horizontally oriented close-packed structure, and avoiding the problem of agglomeration, thereby forming a laminate-type composite. SWCNTs had no effect on the curing process of the PHPS matrix. The SWCNT concentration remained relatively low, resulting in highly transparent composite films. An antireflection effect in the composite film relative to the transmission of the SWCNT film was observed. The results indicate that SiO x N y /SWCNT composites are attractive for applications as protective, antireflective optical coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

The anti-reflection (AR) technology currently used in photovoltaic (PV) glass has reached its operational limit as the refractive index of existing materials cannot be lowered further. To overcome this, in this study, we selected formed methylsiloxane as an AR layer for PV glass. Its low refractive index (∼1.37) originates from the high content of methyl groups and the formation of voids during crosslinking. We acquired and compared the refractive index curves, conducted structural analyses, characterizations (optical, thermal, and surface), and performance evaluations to confirm the advantages of silicone as an AR layer for PV panels. The spreading and subsequent room-temperature self-curing characteristics of silicone considerably enhanced its applicability for upscaling and repair. The hydrophobic nature of the silicone AR layer imparted a new self-cleaning function to the solar panels; further, the methyl-silicone coating enhanced light transmission, resulting in electrical gain. Furthermore, the addition of the methyl-silicone layer created a refractive index gradient on the glass surface, making it fully compatible for use with the mainstream AR process, namely, the sol-gel method employed for PV glass. [ABSTRACT FROM AUTHOR]

This study presents an approach for fabricating super hydrophilic self-cleaning anti-fog micro-nano structures on silicon-coated glass utilizing a laser marking machine. The surface features a periodic microstructure interspersed with irregular nanoparticles, which contribute to its durable superhydrophilicity, maintaining a 0° contact angle for up to one year—the longest duration recorded to date. Moreover, it sustained its anti-fogging and self-cleaning abilities for 467 days, establishing the lengthiest duration for maintaining a 0° contact angle and retaining anti-fogging performance without visible deterioration. The sample also retained excellent anti-fogging and self-cleaning properties even after 43 days of outdoor exposure. Such remarkable performance was attributed not only to surface chemistry and roughness but also to the presence of dense, uniform, and minimally varying microstructures. The unique structure also enhanced the solar spectrum (AM 1.5) weighted average transmission by 3.84 % over control glass in the wavelength range of 400–1100 nm. It holds promising potential for use in automotive rearview mirrors, windows, and solar cells. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of nano-dome anti-reflective coatings (ND-ARC) and nano-cone anti-reflective coatings (NC-ARC) on the optical characteristics of organic light-emitting diodes (OLEDs). By applying anti-reflective coatings on an OLED substrate surface, the glass–air interface reduces reflections, thus boosting the light intensity. The finite-difference time-domain (FDTD) simulation approach and Fresnel theory were leveraged to model the OLEDs and to study the effects of ND-ARC and NC-ARC on the glass–air interface. To enhance parameters such as thickness, refractive indices, pitch, and anti-reflective coating layer height, the Fresnel principle was used. The numerical calculations show that the coupling efficiency of the ND-ARC-coated OLED is improved compared to that of the NC-ARC-coated OLED. The analysis was conducted to observe the effect of various wavelengths on far-field intensities. [ABSTRACT FROM AUTHOR]

Second-generation solar cells, commonly known as thin-film solar cells, have emerged as promising alternatives to traditional silicon-based first-generation photovoltaic cells. The superstrate configuration is the most widely used structure for constructing thin-film solar cells. Nevertheless, light reflection from the front cover glass surface significantly contributes to energy losses in thin-film solar cells. In this study, a ZnO anti-reflection (AR) coating was introduced using the spin coating technique on a glass/FTO/CdS/CdTe/Cu/Au substrate to improve the power conversion efficiency of the solar cell by reducing front-surface reflectance. The ZnO layer deposited at 3000 rpm in 15 s showed the minimum reflectance and higher transmittance over a wavelength range of 500–900 nm. Further, the thickness of the film under optimal conditions was 63.32 nm, which is compatible with the ideal theoretical AR coating thickness of 65 nm. Comparing the device performance of the CdS/CdTe solar cell with and without AR coating, all tested devices showed an average short-circuit current density improvement of 6.8% and overall enhancement in power conversion efficiency of 9.3%. [ABSTRACT FROM AUTHOR]

The modernization that is currently taking over across the world is resulting in numerous advancements in a variety of industries, and the most notable and apparent development is the rising use of solar energy, which has become more prevalent every day. Most companies, residences, schools, and other organizations rely mostly on solar energy as the main source of electricity. It was discovered that anti-reflective coating (ARC) had been applied to solar cells with the goal of increasing power conversion efficiency, decreasing reflection loss, and improving absorption. Although a single layer of ARC is sufficient, applying an additional layer might improve the solar cell application's effectiveness. Hence, the modeling and analysis of double layers of anti-reflection coating (ARC) with different types of materials have been investigated and evaluated using personal computer one-dimensional (PC1D) simulation software. In this study, the double-layer anti-reflection coating on the solar cell was modeled using PC1D, where this software allowed for one-dimensional simulation of the parameters required for the operation of semiconductor-based solar energy systems. The PC1D simulation reveals that SiO2/TiO2 has the highest efficiency (22.82%) and lowest reflection compared to Si3N4/TiO2 and ZnO/TiO2. Also, SiO2/TiO2 generates the highest external quantum efficiency (EQE) among ARC double layers, making it ideal for silicon solar cell applications in order to boost the solar cell's efficiency. The results for the effects of current, voltage, reflection, and EQE of the different double layers of ARC have also been studied in this paper. [ABSTRACT FROM AUTHOR]

The multicomponent cold-recycled asphalt emulsion mixture (CRAEM) has the ability of antireflection cracking between the base and the bottom surface layer, but it has secondary compaction and residual void, which is not conducive to crack resistance and fatigue performance. The application of high-frequency vibration mixing technology can reduce voids and improve crack resistance, but it is limited by the complexity of testing to determine the optimal mixing frequency. The fractal dimension of gradation is deduced by fractal theory, and the prediction model for optimal frequency is proposed. Dry, wet, freeze–thaw splitting tests, and rutting tests were employed to test the early mechanical properties of high-frequency vibration mixing specimens corresponding to different vibration accelerations, and mercury inclusion tests were utilized to compare the void distribution corresponding to the optimal mixing frequency and forced mixing, and to verify the prediction model for optimal frequency. The results indicate that the high-frequency vibration mixing technology is able to benefit the initial cracking resistance (28.1% increase), moisture stability (11.2% increase), and high-temperature stability on the macro level on the optimal frequency. Meanwhile, the void distribution structure can be optimized, reducing the proportion of harmful voids and increasing the proportion of transitional pores on the micro level. However, the freeze–thaw resistance needs to be further studied. This study reduces the number and cost of experiments to determine the optimal frequency, and provides theoretical guidance and technical support for the engineering application of the CRAEM. [ABSTRACT FROM AUTHOR]

The aging failure process of acrylic resin (AR) coatings widely used in ship anti-corrosion systems is highly complex. Currently, there are no established models or methods for predicting the aging of AR coatings in different marine environments. Therefore, this study proposes a framework for predicting the aging of AR coatings in marine environment based on short-term indoor accelerated tests. Initially, a comprehensive aging evaluation method for AR coatings is developed by integrating three commonly used coating performance evaluation indicators (gloss, color difference, and electrochemical impedance) based on the Technique for Order Preference by Similarity to Ideal Solution. Subsequently, an aging severity index is defined to quantify the impact of different environments on the coating aging process. Following this, 14 sets of indoor accelerated aging tests for AR coatings under various environmental conditions are conducted. Based on the test results, a comparative analysis of the predictive performance of three environmental effect models, namely multiple linear regression model, generalized Eyring model, and genetic algorithm-back-propagation model, is performed. Finally, utilizing the environmental effect models and global marine environmental data, the aging severity index of AR coatings in global marine environments is predicted and extrapolated. [ABSTRACT FROM AUTHOR]

Solar cells technology will be one of the futuristic major resources for global energy demands. One of the major problems in energy harvesting using solar cells was reflection of incident light over solar cell surface. The present research work aims to synthesize the magnesium fluoride through sol-gel process which acts as antireflection layer for achieving better output performance. MgF 2 films were deposited over solar cells at varying time periods of 60, 90, 120 and150 min through electrospraying technique. MgF2 electrosprayed solar cells were inspected for evaluating its structural, optical, electrical and morphological characteristics. The coated solar cells were analyzed under dark and light conditions. The precursor materials involved in sol-gel synthesis of MgF 2 were magnesium chloride hexahydride, polyethylene glycol and hydrofluoric acid. From the I–V results, it is evident that performance of 120 min MgF 2 coated solar cell exerts maximum performance of 19.38 % (open) and 19.41 % (controlled). MgF 2 antireflective electrosprayed films were prominent materials for minimizing reflection and ensuring the maximum photon transmission into the coated surface especially in opto-electronic applications. [Display omitted] [ABSTRACT FROM AUTHOR]

4‐(trimethylsilyl)morpholine O(CH2CH2)2NSi(CH3)3 (TMSM) was investigated as a single‐source precursor for SiCNO films synthesis. Optical emission spectroscopy of plasma generated from TMSM/He, TMSM/H2, and TMSM/NH3 gas mixtures revealed the presence of N2, CH, H, CN, and CO species. The last two are suggested to be responsible for the lowering of carbon concentration in the films in comparison with the precursor. The refractive index ranged from 1.5 to 2.0, and bandgap varied from 2.0 to 4.6 eV, which pointed that some of the films can be used as antireflective coatings in silicon photovoltaic cell technologies and dielectric layers in electronic devices. [ABSTRACT FROM AUTHOR]

Aiming at the requirement of radar wave absorption in automotive radar tests for both the 24 GHz and 77 GHz vehicle radar bands, two ultra-thin dual-band circuit analog absorber designs based on frequency-selective conductive film have been proposed. They are obtained by first optimising the equivalent circuit parameters to achieve the desired reflection response, then determining the physical parameters (geometrical size and square resistance) of unit cells from the equivalent circuit parameters, and finally fine-tuning these physical parameters. Both designs employ unit cell based on the nested structure of conductive square ring and a conductive square patch, which has the advantages of simple structure, ease of processing, high design freedom, and good polarisation and angular stability. The 1st design employs different square resistance values for the conductive ring and patch, while the 2nd design employs a single square resistance value for both conductive shapes. Simulation results show that, for each of the two designs, the lower and upper 70% absorption or −10 dB reflection bands simultaneously cover the 24 GHz and 77 GHz vehicle radar bands, respectively, with good angular stability. The dual-band coverage keeps stable until the elevation incident angle reaches 20° and 50° for the 1st and 2nd designs, respectively. A realistic sample is processed regarding the 2nd design and its dual-band absorption performance has been verified by experimental results, which have good agreement with the simulated counterparts. [ABSTRACT FROM AUTHOR]

This paper focuses on minimizing the optical reflection on spherical fused silica lenses using femtosecond (fs) laser nanostructuring. A unique type of nanopillar formation has been observed on SiO 2 surfaces possessing antireflective properties when irradiated with a specific number of overlapping pulses, polarization, and fluence levels. Maintaining precise control over these sensitive technological parameters such as defocus and incident angle during the processing of geometrically complex shapes presents a significant challenge. This study proposes a theoretical optical arrangement to address this limitation by the design of a custom scanner system optimized for curved surfaces. The paper details the optimization process of such a bent image space (inverse-hypercentric) optical system using Zemax OpticStudio. Although the practical realization of the arrangement has not been performed, simulations are conducted to prove the functionality of the concept. Furthermore, we propose a practical method for segmented structuring of spherical surfaces based on consecutive repositioning and irradiation using an industrial robotic arm. By constructing the optical model, the necessary resolution of the segmentation has been calculated for a typical F-Theta scanner system and experimental verification has been performed. [ABSTRACT FROM AUTHOR]

Nanosecond pulsed laser etching for fabricating anti-reflective gratings and inducing synchronous laser annealing was performed on Ag/AZO films. The optimum grating pitch was determined by performance analyses of laser-etched unidirectional gratings, based on which laser-etched bidirectional gratings were fabricated to further determine the optimum grating tilt angle. The results revealed that with the increase of grating pitch, the grating ridge total-side-area was gradually decreased to cause a gradually weakened anti-reflective effect, but the superimposed heat-affected zones between adjacent grooves became smaller or even disappeared, which brought about different synchronous laser annealing effects. The unidirectional grating-textured film with a medium grating pitch of 200 μm showed the best overall performance under the combined influence from anti-reflective gratings and synchronous laser annealing. For the bidirectional gratings, although increasing the grating tilt angle did not change the grating ridge total-side-area, it would enable the laser energy to be more uniformly distributed on the whole film surface, producing a better synchronous laser annealing effect. The bidirectional grating-textured film with a grating tilt angle of 90° had the best overall performance with the highest FOM value of 2.18 × 10−2 Ω−1 that was ∼3.2 times that of the as-prepared film. The results are instructive for preparing high-performance TCO-based films. [ABSTRACT FROM AUTHOR]

The use of renewable energy sources to replace conventional energy sources like fossil fuels is essential. Solar panels are the most widespread technology for clear energy production. However, is crucial to raise the efficiency of solar panels. A large portion of sunlight is reflected by the front surface of the panel and thus the use of an Anti-Reflecting Coating (ARC) has become significant in raising the efficiency of solar panels, through reducing the reflection losses. The ARCs made of natural extracts were utilized to improve the efficiency of Silicon solar panels. The natural extracts were produced from Kailashpati fruit juice and Badminton ball tree flower powder. In the synthesis of these natural extracts, monometallic gallium chloride nanoparticles were used to check their effect on the efficiency of solar power generation. The novelty of this paper is the attempt to mathematically calculate the absorbance of the ARCs, at a particular wavelength, with the use of the refractive indices and thicknesses of ideal ARCs. [ABSTRACT FROM AUTHOR]

This paper introduces a cost-effective, high-performance approach to achieving wafer level vacuum packaging (WLVP) for MEMS-based uncooled infrared sensors. Reliable and hermetic packages for MEMS devices are achieved using a cap wafer that is formed using two silicon wafers, where one wafer has precise grating/moth-eye structures on both sides of a double-sided polished wafer for improved transmission of over 80% in the long-wave infrared (LWIR) wavelength region without the need for an AR coating, while the other wafer is used to form a cavity. The two wafers are bonded using Au-In transient liquid phase (TLP) bonding at low temperature to form the cap wafer, which is then bondelectrical and Electronics d to the sensor wafer using glass frit bonding at high temperature to activate the getter inside the cavity region. The bond quality is assessed using three methods, including He-leak tests, cap deflection, and Pirani vacuum gauges. Hermeticity is confirmed through He-leak tests according to MIL-STD 883, yielding values as low as 0.1 × 10−9 atm·cc/s. The average shear strength is measured as 23.38 MPa. The package pressure varies from 133–533 Pa without the getter usage to as low as 0.13 Pa with the getter usage. [ABSTRACT FROM AUTHOR]

We report a 2.8 μm all-fiber high-power and high-energy gain-switched Er3+:ZBLAN laser based on dielectric fiber mirror and fiber-tip protection. The fiber pigtail mirror, specifically designed for dichroic operation (i.e., anti-reflection at 976 nm pump wavelength and high-reflection around 2.8 μm laser wavelength), shows high damage density of >10 MW/cm2. An anti-reflection protective film is coated on the input tip of Er3+:ZBLAN fiber and an AlF3 endcap is spliced to the output tip of Er3+:ZBLAN fiber for mitigating the fiber-tip photodegradation and high-power catastrophic failure at 2.8 μm. The compact all-fiber cavity is formed by efficiently connecting the Er3+:ZBLAN fiber with dielectric fiber mirror using the standard FC/PC fiber adaptor. When the 976 nm pump operates in pulsed regime, the all-fiber mid-infrared gain-switched laser can be attained with two states of single-pulse and pulse-burst output. The extracted maximum pulse energy is 4.8 μJ in the single-pulse state, and the shortest pulse width is 426 ns. The pulse-burst mode can generate a maximum average power of 5.291 W and burst energy of 264.55 μJ. This work may offer a promising way to realize the low-cost, all-fiber, high-power and high-energy gain-switched laser at MIR wavelengths. [ABSTRACT FROM AUTHOR]

Wafer-scale rare-earth iron garnet (RIG) single crystal thick films were fabricated on 3-in. gadolinium gallium garnet (GGG) substrates using liquid phase epitaxy. The terahertz transmittance of the RIG crystals improved after removing the GGG substrate by polishing. The time-domain spectra at Terahertz (THz) frequencies indicate the existence of a magneto-optical effect in RIG samples. The results indicate that the RIG samples exhibit a high refractive index of ∼4.50 within the 0.1–1.0 THz frequency range, a transmittance of around 40%, and an absorption rate of only 10–50 cm−1. The Faraday rotation angles of the thick single-crystal films of the RIG samples were measured using a THz-TDS system. The RIG has a thickness of ∼330 μm. The Faraday rotation angles of RIG crystals at THz frequencies can reach up to 16° when an external magnetic field of 0.18 T is applied. The Verdet constants of the RIG sample were calculated to be ∼120°/mm/T. To improve the transmittance of the RIG sample, epoxy resin and polymethylpentene (TPX) were used as anti-reflective films. The transmittance of the RIG sample increased by ∼5% for the 80 μm thick epoxy and about 10% for the 320 μm thick TPX. Therefore, this RIG single crystal thick film can achieve a low loss, a high transmittance, and a strong magneto-optical effect in the terahertz region with the cooperation of a reflection-reducing film. It is expected to have wide applications in terahertz magnetic polarization conversion, non-reciprocal phase shifters, and isolators. [ABSTRACT FROM AUTHOR]

This study introduces CeO2/SiO2 double-layer film stacks and its antireflection coating effect. Optical properties were analyzed by spectrophotometer measurements; surface morphology and cross-sections were observed by Scanning Electron Microscopy (SEM); elemental distributions and crystallographic properties were determined by Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) measurements. Average reflectance of single-layer 0.3MSiO2, 0.6MSiO2, and 0.3MCeO2 thin films were 30.54%, 20.12%, and 14.23%, respectively. Average reflectance was decreased significantly down to 5.9% by 0.3MCeO2/0.6MSiO2 double-layer thin films comparing to those of the results of single-layer films and bare silicon surface reflection (~40%). Antireflective effect of the films on solar cells was estimated by simulation using the measured reflection data. Simulated solar cells indicate that 0.3MCeO2/0.6MSiO2 double-layer antireflective coatings are capable to increase the efficiency significantly and conversion efficiency of 21.7% could be achieved. [ABSTRACT FROM AUTHOR]

Fresnel reflection has been known for centuries to fundamentally impede efficient transmittance across planar interfaces, especially at grazing incidence. In this work, the generalized Huygens' condition (GHC) is introduced to resolve such intricacies in metasurface (MS) designs and allow omnidirectional transparency. Compared to common numerical metamaterial approaches, the analytical framework herein yields surprisingly simple closed‐form conditions, carefully leveraging the natural nonlocal mechanisms endowed in planar electromagnetic structures. At the meta‐atom level, the GHC is met by balancing traditional tangential susceptibilities of Huygens' MSs with their unconventional normal counterparts; the latter facilitates the key requisite of vanishing backscattering at the challenging grazing incidence scenario. At the MS level, this central insight is sheerly utilized to engineer realistic all‐angle transparent printed‐circuit‐board (PCB) cascaded admittance sheets. Thoroughly validated in simulation and experiment, this universal GHC demonstrates a resourceful venue for practical implementation of advanced nonlocal devices, e.g., flat optical components, optical analog computers, and spaceplates. [ABSTRACT FROM AUTHOR]

Atomic layer deposited (ALD) TiO2 layers are implanted with N, O, and Ar ions to reduce the bandgap, thereby increasing its absorbance in the visible region. The implantation is accomplished with 40 keV nitrogen, 45 keV oxygen, and 110 keV argon ions in the fluence range 1 × 1015 to 5.6 × 1016 ions cm−2. The energy of each incident ion is tuned using stopping and range of ions in matter (SRIM) to produce defects around the same projected range. The structural analysis of the as‐deposited film is performed through X‐ray diffraction (XRD), scanning electron microscopy (SEM), Rutherford backscattering (RBS), and time of flight elastic recoil detection analysis (ToF‐ERDA). The implanted layers are characterized using diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR) to study the optical and vibrational properties of the films. The results demonstrate that nitrogen implantation in TiO2 reduces the reflectance from 43.52% to 26.31% and bandgap from 2.68 to 2.61 eV, making it a promising bandgap‐engineered material for capping layers in solar cell applications. The refractive index of the 40 keV nitrogen ion implanted film at 1 × 1016 ions cm−2 (N‐16) increases from ≈2.8 to ≈2.95. OPAL2 solar cell simulations show that the N‐16 implanted TiO2 anti‐reflective coatings (ARC) can enhance the absorbed photocurrent by 7.3%. [ABSTRACT FROM AUTHOR]

Antireflective surface coatings were one of the most important factors that contributed to the improvement of the functionality of photovoltaic cells. The coatings were performed by different methods such as RF sputtering, spin coating, dip coating, electro spraying etc. The coating materials such as BN, Si 3 N 4 and BN-Si 3 N 4 blends were applied to solar cells using the RF sputtering technique in this study. Several distinct characterization methods were adopted to assess the productivity of Si 3 N 4 coated cells. The BN-Si 3 N 4 blend coated cell has a low light reflection of 8 % and exhibits uniform layer deposition, which shows a significant improvement over conventional solar cell. The BN-Si 3 N 4 solar cell was able to obtain the highest possible power conversion efficiency of 19.70 % when exposed to direct sunlight and 21.28 % when exposed to neodymium light. It possess the narrow scope of visible spectrum and acts as green/yellow filter in visible spectrum. This light is capable of delivering light similar to sunlight with consistent radiation. This was accomplished by increasing the transmission of photons that reached the depletion region. The four-probe experiment was employed to measure the electrical resistivity of BN-Si 3 N 4 solar cell, which was found to be 0.00298 Ω-cm. This value was lower than the electrical resistivity of other solar cell samples. Based on the results, BN-Si 3 N 4 combination outperformed both coated and bare cells. It was found that BN-Si 3 N 4 blendwas a remarkable antireflective coating to maximize the performance. [ABSTRACT FROM AUTHOR]

Metallic antiferromagnets with chiral spin textures induce Berry curvature-driven anomalous and spin Hall effects that arise from the topological structure of their electronic bands. Here, we use epitaxial engineering to stabilize (111)-oriented thin films of Mn3Ge with a cubic phase. This cubic phase is distinct from tetragonal ferrimagnetic and hexagonal noncollinear antiferromagnetic structures with the same chemical composition. First-principles calculations indicate that cubic Mn3Ge will preferentially form an all-in/all-out triangular spin texture. We present evidence for this noncollinear antiferromagnetism through magnetization measurements with a Néel temperature of 490 K. First-principles calculations of the corresponding band structure indicate the presence of Weyl points. These highlight cubic Mn3Ge as a candidate material for topological antiferromagnetic spintronics. [ABSTRACT FROM AUTHOR]

We report a reflection based multimode fiber surface plasmon resonance (SPR) sensor utilizing a high index silicon layer between silver metal and sensing medium layer. Theoretical studies have been carried out to optimize the suitable width of material layer to sense refractive index (RI) of the analyte surrounding the optical fiber sensing region using the transfer matrix method. The RI sensitivity of the proposed SPR sensor has been experimentally verified to reach 4774 nm/RIU with figure of merit of 36.07 and resolution of 6.28 × 10−5at 1.38 RI. Furthermore, the large thermo-optic coefficient and thermal expansion coefficient of the silicon layer has enhanced the experimental temperature sensitivity of the SPR sensor to 1.76 nm/°C. [ABSTRACT FROM AUTHOR]

A high sensitivity sensor is proposed to measure axial strain, magnetic field, and refractive index. Hollow‐core fiber (HCF) and single mode fiber (SMF) are fused together to form the "SMF–HCF–SMF," then tapering HCF, and finally forming a sensor. The light in the sensor structure forms an antiresonant reflection optical waveguide mechanism. The sensor has particularly thin waist circumference, therefore the surface evanescent field of the sensor is easily affected by environmental parameters, making it particularly sensitive to environmental parameters. The axial strain sensitivity obtained by the sensor is as high as −31.87 pm/µε. The magnetic field sensitivity obtained by combining the sensor with magnetostrictive material Terfenol‐D in the range of 10–40 mT is 123.9 pm/mT. The sensor measures the refractive index of NaCl solution with a sensitivity of up to 2109.308 nm/RIU (RIU: refractive index unit). Additionally, the sensor has good stability and repeatability when measuring three physical quantities. The sensor has a compact structure, stable performance, simple manufacturing, and can measure multiple parameters in biochemical engineering, industrial structural health detection, and marine resource detection. [ABSTRACT FROM AUTHOR]

Black GaAs nanotip arrays (NTs) with 3300 nm lengths were fabricated via self-masked plasma etching. We show, both experimentally and numerically, that these NTs, with three gradient refractive index layers, effectively suppress Fresnel reflections at the air–GaAs interface over a broad range of wavelengths. These NTs exhibit exceptional UV-Vis light absorption (up to 99%) and maintain high NIR absorption (33–60%) compared to bare GaAs. Moreover, possessing a graded layer with a low refractive index (n = 1.01 to 1.12), they achieve angular and polarization-independent antireflection properties exceeding 80° at 632.8 nm, aligning with perfect antireflective coating theory predictions. This approach is anticipated to enhance the performance of optoelectronic devices across a wide range of applications. [ABSTRACT FROM AUTHOR]

Antireflection surfaces are widely used in optical devices (such as vehicle display, solar cells, and architectural glass) to reduce the reflection and increase transmittance. Plasma etching shows great potential in making subwavelength antireflection structures for its advantage of scalable, low‐cost, and applicable in flexible substrates. Here, we demonstrate an antireflection nanostructure by O2 plasma etching on poly (ethylene terephthalate) (PET) substrate without additional corrosive gas species or antireflective coatings. Nanopores on the surface were formed due to the different etching rates of the organic region and silica region of the surface. The solar weighted average transmittance was improved from 91.6% to 94.8% for single‐side treated PET with silica antiblocking layer. The transmission increment was attributed to the gradient refractive index of the nanostructured surface due to the elimination of step discontinuity in refractive index. The result shows a highly efficient, eco‐friendly, solvent‐free, economical, and sputtering target‐free method for reducing the reflection and increasing the transmittance of the substrates. [ABSTRACT FROM AUTHOR]

Conductive textiles with electromagnetic interference (EMI) shielding functionality are highly desirable for growing flexibility requirements of EMI shielding devices. Most extant shielding coatings on textiles rely on rigid nanomaterials, which are susceptible to detachment, and generate a great deal of reflected EM waves. Thus, there is a high demand for shielding coatings on textiles that are stretchable, stable, and capable of suppressing the secondary reflection toward incident EM waves. Liquid metal is a particularly suitable candidate owing to its high electrical conductivity and excellent conformality. Herein, a straightforward coating strategy is developed for fast fabrication of Ion/Clay‐F that is reinforced with ionogel encapsulation. Especially, the method enables the direct transformation of fluid‐like liquid metal into a clay‐like state and the preparation of ionogel sealings from monomer solutions. The resulting Ion/Clay‐F exhibits promising features, including high total EMI shielding effectiveness (SET) (highest value of 49.3 dB for a single layer and an average value of 73.0 dB for three layers), low reflectivity (0.404), improved tensile strength (13.16 MPa) and tolerance in a wide range of temperatures (−18–100 °C). Remarkably, such Ion/Clay‐F outperforms pure cotton fabric in terms of thermal management, delivering superior heat dissipation and thermal insulation properties. [ABSTRACT FROM AUTHOR]

Currently, coating with anti-reflective materials is an attractive approach to improve the quality of screen-based displays. In this study, mesoporous silica particles were systematically synthesized as a function of surfactant (i.e., CTAC-cetyltrimethylammonium chloride) concentration to serve as main coating fillers possessing low refractive indices. Precisely changing the amount of the CTAC surfactant, silica sol with an average diameter of 50 nm exhibits distinctively different specific surface areas, pore size, and pore volume. Prior to the preparation of final coating solutions containing these silica particle fillers, the percentage of solid content was optimized on a glass slide. The use of 50 wt% solid content exhibited the highest transmittance of light. Among various content levels of silica sol, the use of 3.5 wt% of silica particles in the solid content displayed the highest transmittance (i.e., best anti-reflectiveness). Under the almost identical coating layers prepared with the fixed amount of silica particles possessing different surface areas, pore size, and pore volume, it appears that the largest pore volume played the most important role in improving the anti-reflective properties. Experimentally understanding the key feature of low-refractive filler materials under the optimized conditions could provide a clear view to develop highly effective anti-reflective materials for various display applications. [ABSTRACT FROM AUTHOR]

In this research, a front layer of indium tin oxide (ITO) is added on the top surface of copper zinc tin sulfide (CZTS)/zinc oxide (ZnO) thin film solar cell. The goal of this paper is to improve the absorption values against the angle of incidence through visible wavelengths. The transfer matrix approach and the finite element method were extensively used in the design and simulation process. The numerical findings are investigated with the help of COMSOL multiphysics software as well. Recently, it has been found that the angle of incidence significantly reduces the solar cell absorption. To prevent such increment of absorption losses as the angle of incidence rises, the numerical findings have deduced that it may therefore be of interest to include an anti-reflecting coating of ternary one-dimensional photonic crystals on a single unit cell. Meanwhile, the anti-reflective coating is designed with three different geometries: planar, convex, and concave. The investigated results demonstrated that the concave geometry is efficient in controlling the absorption losses of the designed CZTS/ZnO thin film solar cell against the increase in the angle of incidence. In this regard, for an angle of incidence less than 50°, the solar cell absorption values remain greater than 0.9055 all over the visible spectrum. Therefore, a relatively high performance of this cell is strongly expected. [ABSTRACT FROM AUTHOR]

This study focuses on the fabrication and characterization of a transparent conductive window with high transmission properties. The window is created by depositing optimized antireflection layers on quartz glass to emphasize the spectral range of 450–800 nm at an incidence angle of 35°. The deposition process involves an antireflection layer to minimize reflection and achieve a transmission level above 91% within the specified spectral range. The thin film demonstrates the excellent optical properties of the fabricated transparent conductive window, making it suitable for a wide range of applications requiring high transmission and resistance to laser-induced damage. This research provides insights into the fabrication and performance of transparent conductive windows, laying the groundwork for potential applications in optics and industrial settings. [ABSTRACT FROM AUTHOR]

The elastic, vibrational, and electro-optical properties of WSe2 using the first-principles approach have been explored in this study. The lattice parameters of WSe2 are consistent with the available results. The structural stability of WSe2 has been proven by satisfying the stability conditions and from the phonon dispersion spectra. According to the elastic constants and moduli, WSe2 is a material with a high level of machinability, rather soft, mechanically and elastically anisotropic, and brittle in nature. The relatively lower values of the thermodynamic parameters suggest that WSe2 could be an excellent option as a thermal barrier coating (TBC) material. The overlap of the acoustic and optical modes of phonons in the lower frequency region is responsible for the enhancement of the anharmonicity of the crystal and hence reduces the thermal conductivity. WSe2 is an indirect band gap material with band gap values 0.88 (LDA) and 1.329 eV (sX-LDA) with small values of carrier effective mass. Therefore, WSe2 could be a potential candidate for electronic device applications. The optical investigation revealed that the material has a high refractive index, dielectric constant, and absorption coefficient, and considerable optical anisotropy. According to the reflectivity spectra, WSe2 could be employed as an anti-reflection coating material. By examining the optical properties, it can be noted that WSe2 is widely used to develop wave-guides, photonic devices, photovoltaic cells, and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Developing high-performance mid and far infrared antireflection films is a significant requirement in the field of infrared optics. This study successfully prepared AR films composed of ZnS nanospheres for mid and far infrared bands using a combination of hydrothermal and sol-gel methods. Initially, ZnS nanospheres with uniform size and good monodispersity were synthesized via the hydrothermal method and subsequently coated on CdSe substrate through dip coating. The refractive index of the ZnS film is adjusted between 1.36 and 1.52. A significant AR effect was observed in ZnS nanospheres film on CdSe substrate at 3–5 μm and 8–14 μm, and the reflectance is approximately 3 % which is about 25 % lower than that of the uncoated sample. Upon coating with a TiO 2 protective layer, the reflectivity further decreased to about 0.6 % and the film demonstrated excellent weather resistance and mechanical properties. This work provides a novel approach for the preparation and regulation of mid and far infrared AR film, significantly contributing to the development of optical film. [ABSTRACT FROM AUTHOR]

All astronomical missions use charge-coupled devices (CCDs) as vital organs. Usually, silicon (Si) is preferred to build them, which does not perform well without enhancements such as anti-reflection (AR) coatings. Such devices exhibit poor performance in the large (> 800 nm) and small (< 500 nm) wavelength ranges, even with AR coatings. We present studies that signify gallium nitride (GaN) as a potential replacement for Si in astronomical CCDs that operate in a wide wavelength range. For this purpose, SILVACO TCAD software has been used for simulating and comparing the electronic and optical properties of a GaN CCD pixel with a Gaia astrometric field (AF) CCD pixel. Our observations demonstrate that the electronic and optical performance of the GaN-based CCD pixel is significantly better than the Si-based AF CCD pixel. These findings can prove to be the bedrock of future astronomical exploration and broadband astronomical CCDs, as the simulated GaN CCD pixel exhibits a high quantum efficiency even without any reinforcements. [ABSTRACT FROM AUTHOR]

A thin film of 7-oxo-thiazolopyrimidine-3,8-dicarbonitrile derivative [7-ThPyDi]TF was prepared using a spin coating technique. The surface morphology and molecular structure are studied using various techniques such as XRD, FTIR, and scanning electron microscope (SEM). Moreover, the quantum chemical calculations were carried out through time-dependent density functional theory (TD-DFT) to investigate some reactivity descriptors such as softness and electronegativity. Also, Au/[7-ThPyDi]TF/p-Si/Al heterojunction diodes were fabricated. It was revealed that the energy bandgap value of [7-ThPyDi] as an organic thin film is 3.58 eV for direct transitions and 3.94 eV for indirect transitions, respectively, and this value falls within the semiconductor material range. The atomic force microscope demonstrated that the surface roughness of the thin film is approximately 32.2 nm. Because of its high refractive index, this material has the potential application as an antireflection coating for solar cells and as lenses with a wide focal range. We investigated a blue luminescent thiazolopyrimidine compound; the maximum emission in the more aggregated state (higher solution concentration) exhibits a notable blue shift compared to the more diluted solution. This uncommon phenomenon has been understood by structural analyses using density functional theory. The chemical structure of the molecule [planar conjugated cores and strong polar groups (–CO and –CN)] enables it to interact with both itself and the polar solvent. The intermolecular interactions result in the bending of the conjugated plane. As a result, the blue shift happens upon aggregation when the conjugated effect becomes weaker. The studied molecule gave different emission colors (blue, yellow, and reddish green) depending on the molecular packing. [ABSTRACT FROM AUTHOR]

Precise surface reflectance control at specific deep‐ultraviolet (DUV) wavelengths across wide angles is crucial for semiconductor inspection and lithography tools. The inherent challenges in designing DUV antireflective multilayers stem from limited transparent materials and the resultant fabrication complexity owing to numerous interfaces. Here, wide‐angle antireflective multilayers finely tuned to 248 nm designed using an active learning scheme is presented. The active learning scheme employing factorization machines (FM) identifies the optimal configurations for binary‐material‐based multilayers (AlF3/LaF3, AlF3/MgF2, and AlF3/Al2O3) with varying index contrasts, achieving minimal figure‐of‐merit (i.e., average angular reflectance) values at predetermined total thicknesses. High‐index‐contrast AlF3/Al2O3 multilayers are fabricated via atomic layer deposition, thus enabling the conformal coating of high‐numerical‐aperture (NA) lenses with atomic precision. An optimized AlF3/Al2O3 tri‐layer with a total thickness of 180 nm results in an average (0°–45°) reflectance of 0.4% on a CaF2 planar substrate and 0.6% on a CaF2 convex lens (NA = 0.47), similar to the performance of an ideal single‐layer coating requiring a practically unavailable refractive index. Phasor analysis, which considers only first‐order reflections between adjacent layers, supports the benefits of high‐index‐contrast binary materials and the use of the FM‐based active learning scheme in antireflective multilayer design. [ABSTRACT FROM AUTHOR]

In this work, a thermally tunable optical resonator operating in the visible wavelength range is reported, which consists of a bilayer structure composed of a thin silver layer and a dielectric coating of [Fe(HB(1,2,4‐triazol‐1‐yl)3)2] switchable spin‐crossover (SCO) molecules. White light is coupled to the resonant structure using a prism and the resulting resonance spectra are investigated as a function of the incident angle and temperature. Switching the SCO molecules from the low‐spin to the high‐spin state gives rise to a substantial blueshift of the resonances reaching up to 30 nm (associated with a reflectance modulation of up to 70%), which can be linked, through transfer‐matrix simulations, to the variation of the optical thickness of the molecular layer. Interestingly, the study demonstrated that the large thermal tunability of the device also gives rise to a photothermal nonlinearity, which can be leveraged for achieving optical limiting applications. Overall, through the present study, it is shown that molecular SCO nanomaterials can be superior to commonly used thermo‐optical switches and well‐established optical phase‐change materials for applications requiring high broadband optical transparency in the visible spectral domain. [ABSTRACT FROM AUTHOR]

Three-dimensional magneto-optical traps (3D-MOTs) are an integral component of atomic clocks, quantum computers, and other cold-atom science applications. Due to the dependence on bulk optics and lasers, conventional 3D-MOTs occupy a large volume, limiting their portability. Efforts to build 3D-MOTs using integrated photonics promise to reduce the size and weight of these systems allowing applications beyond the lab. However, the need for counterpropagating beams to facilitate 4- and 6-beam geometries necessitates free-space mirrors and quarter wave plates (QWPs) that limit integration. Replacing these mirrors and QWPs with planar retroreflecting metasurfaces provides a route to achieving a complete 3D-MOT within an integrated package. Here, we report on the design and demonstration of a retroreflecting metasurface for 3D-MOTs that operates at large angles and preserves circular polarization. Specifically, we utilize Bayesian optimization to design an amorphous silicon (a-Si) on gold metasurface for high efficiency polarization-insensitive retroreflection of 780 nm circularly polarized light at 54.7°. Numerical simulations demonstrate maintenance of circular polarization after highly efficient retroreflection ( ϵ − 1 = 1.10 , R − 1 = 0.86). Experimentally, we demonstrate similarly excellent performance at 736 nm at 50.3 ° ( ϵ − 1 = 1.04 , R − 1 = 0.73) and show that deviation from the target design is due to oxidation of the a-Si metaelements. We conclude by discussing mitigation strategies for future devices and propose a corrective optic for the currently fabricated device. This work represents a step toward the miniaturization of 3D-MOTs and expansion of cold-atom science beyond the laboratory. [ABSTRACT FROM AUTHOR]

With the rapid growth of the electronic display industry, aluminosilicate glass has emerged as a replacement for traditional soda lime silica glass as the cover plate of various display devices because of its excellent physical and chemical properties. High transmittance and low reflectivity are the inevitable requirements of its application. However, few studies have been reported about the antireflection of aluminosilicate glass. In this study, a two-step etching method was employed to treat both sides of the alkali-aluminosilicate glass to obtain surface antireflection. Analytical methods such as EPMA, AFM, and UV spectrophotometry were utilized to evaluate the effect of the etching process and resultant surface microstructure on the optical properties of the glass. Furthermore, comparative research was conducted to distinguish the etching reaction differences between alkali-aluminosilicate glass and other glass compositions like soda-lime glass and high-boron-silicon glass. The results demonstrated that the controlled two-step etching process created a micro-porous surface structure, with a gradient refractive index. Subsequent to the secondary etching, the glass exhibits an impressive average transmittance of 98.88% within the visible light spectrum (380–780 nm). Moreover, identical etchant across different composition glasses leads to discernible differences in transmittance. [ABSTRACT FROM AUTHOR]

MoAlB, known for its exceptional oxidation resistance and anti-ablation properties, holds significant promise as a protective thin film for high-temperature components in military equipment. However, the high thermal conductivity of MoAlB poses a challenge to its compatibility with infrared stealth performance. In this study, structural defects were intentionally implanted into the MoAlB thin film by leveraging the amplified Kirkendall effect to hinder heat propagation. The results revealed that the MoAlB MAB phase thin film with a notable amount of edge dislocations was achieved by subjecting the post-annealed (Mo–B)/Al nanostructured multilayers (NMs) to an elevated temperature of 700 °C. The room-temperature resistivity of the thin film was 1.43 μΩ m. Furthermore, the infrared emissivity of the thin film was assessed within the mid-infrared wavelength range, ranging from 0.11 to 0.25. Simultaneously, the resulting thin film was found to possess a low thermal conductivity of 11.44 W m−1 K−1, consequently achieving excellent infrared stealth capability. [ABSTRACT FROM AUTHOR]

While terahertz (THz) technology offers a variety of applications in medical diagnosis, nondestructive testing, and quality control, its acceptance in these practical fields is hampered by the absence of endoscopic systems, capable of sensing the complex refractive index of the hard-to-access objects. In this paper, we develop the THz endoscope based on the hollow-core antiresonant waveguide, formed by a polytetrafluoroethylene (PTFE)-coated sapphire tube with the outer end closed by a monolithic sapphire window. The endoscope is attached to the backward wave oscillator spectrometer to measure the sample reflectivity. By studying the well-known liquid and solid samples, we demonstrate that analysis of the Fabry–Pérot resonance in the measured reflection spectra makes it possible to quantify the complex refractive index of an analyte. Thanks to the advanced chemical inertness and thermal strength of sapphire and PTFE, the developed endoscope is capable of operation in harsh environments, which broadens the range of its applications. Our findings pave the way for the THz technology use in a number of demanding practical fields. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have become promising candidates for thin‐film photovoltaics (PV), but many record cells suffer from losses in current (≈3–4 mA cm−2). This is due to the choice of superstrate configurations (i.e., glass‐side illumination) and thin absorber layers, typically on the order of ≈500 nm. Illumination through a top transparent conductive oxide electrode (substrate configuration) using LiF and Al2Ox as anti‐reflective coatings leads to reflectance losses below 1% is demonstrated. When combined with 1 µm thick absorber layers, substrate configurated bifacial devices have power conversion efficiencies >20%, with minimized reflection losses approaching 98% of their detailed‐balance limits and higher Jsc than their monofacial counterparts. Further analysis is conducted to show there is still a significant fraction of current lost due to poor charge‐carrier extraction (e.g., resistive or low mobility contacts). This is studied by a direct comparison of photoluminescence at short‐circuit versus open‐circuit estimating a 4.5% loss in charge‐carrier collection. [ABSTRACT FROM AUTHOR]

Leaky mode resonances of the setae of Cataglyphis bombycina are found to enhance the thermal emission of the animals by near field coupling to the chitinous exoskeleton. This is remarkable, as the setae are also an adaption to enhance the reflectivity in the visible wavelength range. Both effects are dependent on morphology, dimensions and spatial arrangement. These parameters were experimentally characterized and simulated by finite difference time domain simulations to elucidate the optical impact of the setae in the mid infrared range and the contribution of leaky mode resonances. This mode of action and the setae's optical properties in the visible range explain evolutionary strains that led to the actual morphology and size of the setae. [ABSTRACT FROM AUTHOR]