Antireflection Ability Research Articles

A novel reflective interference mitigation model for laser stripe extraction

In practical applications of line-structured light measurement technology, the transmitted laser may be reflected several times due to the reflective properties of the measured object’s surface, which directly affects the accuracy of three-dimensional (3-D) measurements. To obtain precise laser stripes under such reflective conditions to improve measurement accuracy, this paper proposes a semantic segmentation method called GuideNet. Firstly, a dual-branch encoder is introduced to simultaneously extract high-resolution spatial features and high-level semantic features from the input image. Secondly, a Guidance module is designed to fuse spatial features and semantic features and enhance the model’s ability to focus on relevant regions. Finally, the multi-level feature fusion decoder is performed to obtain the final results. Experiments on RIDataset and 3-D measurement experiments demonstrate that the proposed method improves the anti-reflection ability of line-structured light sensors.

Ultra-broadband, high-efficiency metamaterial absorber based on particle swarm optimization algorithm

In this study, we propose an ultra-broadband, high-efficiency absorber based on the particle swarm optimization (PSO) algorithm. By coupling multi-layer planar structures with pyramid structures and optimizing structural parameters using code, the absorber can achieve efficient absorption in the ultra-broadband band. According to the simulation results, the average absorptance of the absorber exceeded 99.98% in the wavelength range from 300 nm to 2000 nm. Due to the gradual geometric structure of the pyramid, excellent anti-reflection ability can be achieved, and it has a high degree of symmetry, making the absorber insensitive to the incident angle and polarization state. The simulation results also show that the absorption efficiency can reach more than 90% when the incidence angle varies from 0° to 60°. Due to the high thermal and chemical stability of SiO2, Ti, and TiN materials, the absorber can be used in a wider range of fields. This study not only proposes an efficient absorption structure, but also provides an idea for the design optimization of absorbers.

Dual layer chessboard metasurface sandwiched by a spin-on-carbon for spectral modulation.

Metasurfaces, composed by metals and dielectrics in periodical order with subwavelength pitches, are of great importance for their unique ability to abruptly manipulate optical fields. So far, all the reported metasurfaces are constructed by thermally deposited metals and dielectric films, based on semiconductor processes which are expensive and time-consuming. Inspired by the outstanding dry etch property of spin-on-carbon (SOC) as the interlayer material in CMOS technology, this paper proposes to utilize the SOC as the dielectric layer in a chessboard metasurface with dual layer of gold to form an array of local surface plasmonic resonators (localized surface plasmon resonance). Finite difference and time domain (FDTD) method is used to investigate the spectral characteristics in reflectance of the metasurface in both visible and short wavelengths of infrared light. Electron beam lithography is applied to generate the nanoscale chessboard pattern on ZEP520A, followed by a conventional oxygen-based plasma etch to form high aspect ratio nanopillar arrays in SOC with the feature width under 50 nm, and ended by a thermal deposition of gold to form self-aligned dual layer local surface plasmonic resonators (LSPRs). The measured reflectance spectra agree with the simulated. A wealth of optical properties, such as coupling induced modulations of spectra by LSPRs, are revealed and analyzed. These special modes result in tunable structural colors and wavelength-selective antireflection ability. To the best of our knowledge, this is the first time that SOC is applied in the construction of metasurfaces, which has great potential for next generation nanophotonic devices.

Optimization design of fiber rubber asphalt gravel sealing layer based on fatigue crack resistance test.

Crack is one of the main diseases of pavement structure. In order to improve the anti-reflective crack ability of pavement, fiber rubber gravel sealing layer is proposed as the stress absorbing layer. In view of the shortcoming that Mcleod design method can not be associated with road performance, a sealing layer optimization design method based on fatigue crack test is proposed. Firstly, the reinforcement effect of fiber on rubber asphalt was studied through force ductility testing. Secondly, the optimum dosage of fiber, asphalt and gravel was optimized through fatigue cracking resistance test. Finally, the cracking resistance of fiber rubber gravel seal was verified through fracture energy test. The results show that fibers can significantly increase the maximum tensile force and strain yield energy of rubber asphalt, and basalt fiber has the best reinforcement effect. The most obvious effect on cracking resistance performance in the sealing layer is the amount of fiber, followed by the amount of asphalt, and finally the amount of gravel. The optimized material combination with the best crack resistance is 120g/m2 fiber, 14kg/m2 gravel and 2.4kg/m2 rubber asphalt, and the fatigue resistance times can reach 19532 times. The fracture energy of the composite pavement treated by the optimized sealing layer is nearly double that of the non-treated pavement structure, and it has a good anti-crack effect.

Physiochemical Coupled Dynamic Nanosphere Lithography Enabling Multiple Metastructures from Single Mask.

Metastructures are widely used in photonic devices, energy conversion, and biomedical applications. However, to fabricate multiple patterns continuously in single etching protocol with highly tunable photonic properties is challenging. Here, a simple and robust dynamic nanosphere lithography is proposed by inserting a spacer between the nanosphere assembly and the wafer. The nanosphere diameter decrease and uneven penetration of the spacer during etching lead to a dynamic masking process. Coupled anisotropic physical ion sputtering and ricocheting with isotropic chemical radical etching achieve highly tunable structures with various 3D patterns continuously forming through a single etching process. Specifically, the nanosphere diameters define the periodicity, the etched spacer forms the upper parts, and the wafer forms the lower parts. Each part of the structure is highly tunable through changing nanosphere diameter, spacer thickness, and etch conditions. Using this protocol, numerous structures of varying sizes including nanomushrooms, nanocones, nanopencils, and nanoneedles with diverse shapes are realized as proof of concepts. The broadband antireflection ability of the nanostructures and their use in surface-enhanced Raman spectroscopy are also demonstrated for practical application. This method substantially simplifies the fabrication procedure of various metastructures, paving the way for its application in multiple disciplines especially in photonic devices.

Optimization of retinin expression and the application with wax emulsion in nanocoatings

Anti-reflective nanocoatings that mimic the eyes of fruit flies are biodegradable materials with great market potential for a variety of optical devices that require anti-reflective properties. Microbial expression of retinin provides a new idea for the preparation of nanocoatings under mild conditions compared to physicochemical methods. However, the current expression level of retinin, the key to anti-reflective coating, is low and difficult to meet mass production. In this study, we analyzed and screened the best expression hosts for Drosophila-derived retinin protein, and optimized its expression. Chinese hamster ovary (CHO) cells were identified as the efficient expression host of retinin, and purified retinin protein was obtained. At the same time, the preparation method of lanolin nanoemulsion was explored, and the best anti-reflective ability of the nano-coating was determined when the ratio of specific concentration of retinin protein and wax emulsion was 16:4, the pH of the nano-coating formation system was 7.0, and the temperature was 30 ℃. The enhanced antireflective ability and reduced production cost of artificial antireflective nanocoatings by determining the composition of nanocoatings and optimizing the concentration, pH and temperature of system components may facilitate future application of artificial green degradable antireflective coatings.

Reflection power suppression for solid state amplifiers with combiner optimization.

The application of high-power solid state amplifiers (SSAs) in accelerator facilities is increasing, and equipment failure caused by reflected power is the main risk to their long-term operation. High-power SSAs often comprise multiple power amplifier modules. Full power reflection is more likely to damage the modules in SSAs if the amplitudes of the modules are unequal. Optimization of the power combiners is an effective means for improving the stability of SSAs under high power reflection. This study analyzes the mechanisms and conditions of reflected power generation using the scattering parameters of the combiner and proposes an optimization scheme for the combiner. The simulation and experimental results show that some modules may receive reflected power as high as nearly four times the rated power of one module when the SSA meets certain conditions, which could damage the modules. The maximum reflected power can be effectively reduced and the anti-reflection ability of SSAs can be improved by optimizing the combiner parameters to suppress the maximum reflected power.

Перспективный путь повышения эффективности кремниевых солнечных элементов --- введение нитевидных кристаллов с p-n-переходом

A new approach to increasing the efficiency of silicon solar cells (SCs) is presented, which consists in the creation of surface light-trapping structures with a high antireflection ability in the form of systems of pointed whiskers (NCs) with coaxial p–n junctions. The coaxial geometry of the p–n junction is justified in terms of the efficiency of collection and separation of minority charge carriers (NCCs) due to the built-in electric field across the junction. Received solar cells with improved photoelectric characteristics and an efficiency factor (COP) of 20.43%.

A promising way to improve the efficiency of silicon solar elements --- introduction of whiskers with p-n junction

A new approach to increasing the efficiency of silicon solar cells (SCs) is presented, which consists in the creation of surface light-trapping structures with a high antireflection ability in the form of systems of pointed whiskers (NCs) with coaxial p-n junctions. The coaxial geometry of the p-n junction is justified in terms of the efficiency of collection and separation of minority charge carriers (NCCs) due to the built-in electric field across the junction. Received solar cells with improved photoelectric characteristics and an efficiency factor (COP) of 20.43%. Keywords: solar cell, light absorption, p-n junction, silicon.

A Simple Polypyrrole/Polyvinylidene Fluoride Membrane with Hydrophobic and Self-Floating Ability for Solar Water Evaporation.

The traditional hydrophobic solarevaporator is generally obtained through the modification of alkyl or fluoroalkyl on the photothermal membrane. However, the modified groups can easily be oxidized in the long-term use process, resulting in the poor salt resistance and stability of photothermal membrane. In order to solve this problem, a simple polypyrrole/polyvinylidene fluoride membrane, consisting of an intrinsic hydrophobic support (polyvinylidene fluoride) and a photothermal material (polypyrrole), was fabricated by ultrasonically mixing and immersed precipitation. This photothermal membrane showed good self-floating ability in the process of water evaporation. In order to further improve the photothermal conversion efficiency, a micropyramid structure with antireflective ability was formed on the surface of membrane by template method. The micropyramids can enhance the absorption efficiency of incident light. The water evaporation rate reached 1.42 kg m−2 h−1 under 1 sun irradiation, and the photothermal conversion efficiency was 88.7%. The hydrophobic polyvinylidene fluoride ensures that NaCl cannot enter into membrane during the evaporation process of the brine, thus realizing the stability and salt resistance of polypyrrole/polyvinylidene fluoride in 3.5%wt and 10%wt NaCl solution.

Resilient moth-eye nanoimprinted antireflective and self-cleaning TiO2 sputter-coated PMMA films

Moth-eye nanostructures are amongst the most remarkable surfaces in nature because of their multi-functionality including antireflection, self-cleaning and bactericidal ability. Moth-eye surfaces consist of subwavelength arrays of tapered nanostructures, which are challenging to reproduce artificially. Nanoimprint lithography is probably one of the most suited technologies for this purpose. However, the poor mechanical resilience and durability of the polymeric nanocones when exposed to the environment, hinders their use in actual applications. To overcome these limitations, this work demonstrates the use of a thin oxide coating over the polymer moth-eye features imprinted on poly methyl methacrylate (PMMA) films. Particularly TiO2 conformal thin film coatings are deposited by unipolar pulsed dc magnetron sputtering over the antireflective nanopatterns acting as encapsulant. The coating, while preserving the antireflective properties, protects the nanostructures against mechanical scratching and improves substantially their thermal stability to over 250 °C. Furthermore, the TiO2 layer provides additional photoinduced self-cleaning functionality and at the same time it protects the matrix from UV photodegradation. The robust and durable antireflective surfaces developed here may find application on solar cells covers, flat panel displays or on optical components.

Enhanced Efficiency of Graphene-Silicon Schottky Junction Solar Cell through Pyramid Arrays Texturation

Graphene/silicon (Gr/Si) Schottky junction solar cells have attracted extensive research interest due to their simple structure and potential low-cost. Surface texturing is an important part of high-efficiency solar cells. In this paper, the effects of TMAH concentration, IPA concentration and etching time on the structure and anti-reflection ability of silicon pyramid array (SiPa) were systematically studied to obtain uniform and reliable pyramid array. Under the optimized conditions, a large scale SiPa with uniform size distribution was obtained and applied to Gr/Si solar cells. The results show that the TMAH etched SiPa has a better Schottky junction contact between graphene and the SiPa surface, and the SiPa can further improves the ability of collecting photogenerated carriers. Compared with Gr/Si solar cells, the power conversion efficiency (PCE) of Gr/SiPa device is 1.66 times higher than that of Gr/Si solar cells. Finally, Gr/SiPa devices with PCE of 5.67% is successfully obtained by HNO3 doping. This work proposes a new strategy for TMAH etching SiPa to improve the performance of Gr/Si solar cells.

Enhanced performance of Si/PEDOT: PSS heterojunction solar cells via multi-walled carbons coated with polydopamine

n-Si/PEDOT: PSS heterojunction solar cells are expected to be the alternative for photovoltaic technique for the potentially excellent power conversion efficiency and ease of processing. Herein, a multi-walled carbon nanotubes network coated with polydopamine (MWCNTs&PDA) was applied as an interlayer between silicon substrate and PEDOT:PSS film to enhance the performance of Si/PEDOT:PSS heterojunction device in this study. When the film was applied as an interlayer, the average reflectance of the device within the wavelength range 400–1000 nm dropped from 13.6 % to 8.33 %. The enhanced antireflection ability meant more photon-generated carriers were excited. The introduction of PDA reduced the contact angle from 84.5° to 47° on Si surface, and the minority carrier lifetime (τ) was 2.16 times increase. The high charge separation and improved junction effect of MWCNTs&PDA films incorporated between PEDOT:PSS and Si substrate result in advantageous networks of charge carriers, which is confirmed by the excellent open-circuit voltage (Voc) 637 mV, short-circuit current density (Jsc) Jsc 34.76 mA/cm2 and fill factor (FF) 56.41 %. The power conversion efficiency improved to 12.49 % when the MWCNTs&PDA film was incorporated. The achievements of this study indicated that the MWCNTs coated with polydopamine as an interlayer is a promising material for excellent performance Si/PEDOT:PSS heterojunction solar devices.

Coupled Superhydrophilic PMMA Film with Inverted Pyramid Microstructures for Antireflection and Antifogging Properties

Transparent substrates with antifogging and antireflection ability are of extreme significance for optical devices, because they alleviate performance loss and maintenance costs. Here, we reported that a multifunctional film, with excellent mechanical properties, can be fabricated on the PMMA surface via the micro-transfer printing method. In particular, the synergistic effect of the inverted pyramid microstructure and SiO2 nanoparticles gives the film excellent antireflective, superhydrophilic and antifogging properties, and the silica sol firmly adheres to the PMMA substrate via the silane coupling agent, which exhibits an encouraging prospect of practical applications from lenses for personal and sports eyewear to transparent displays and sensors, etc.

Fabrication of Needle-Like Silicon Nanowires by Using a Nanoparticles-Assisted Bosch Process for Both High Hydrophobicity and Anti-Reflection.

In this work, a modified Bosch etching process is developed to create silicon nanowires. Au nanoparticles (NPs) formed by magnetron sputtering film deposition and thermal annealing were employed as the hard mask to achieve controllable density and high aspect ratios. Such silicon nanowire exhibits the excellent anti-reflection ability of a reflectance value of below 2% within a broad light wave range between 220 and 1100 nm. In addition, Au NPs-induced surface plasmons significantly enhance the near-unity anti-reflection characteristics, achieving a reflectance below 3% within the wavelength range of 220 to 2600 nm. Furthermore, the nanowire array exhibits super-hydrophobic behavior with a contact angle over ~165.6° without enforcing any hydrophobic chemical treatment. Such behavior yields in water droplets bouncing off the surface many times. These properties render this silicon nanowire attractive for applications such as photothermal, photocatalysis, supercapacitor, and microfluidics.

A superhydrophobic film of photovoltaic modules and self-cleaning performance

For photovoltaic (PV) modules, dust accumulation is one of the reasons for the reduction of output power, while conventional cleaning is expensive and inefficient for large scale PV power plants. Therefore, the research of superhydrophobic self-cleaning thin film on PV modules is proposed in this paper. The preparation of superhydrophobic film combines the low surface energy layer and anti-reflection layer which enhances the adhesion between the superhydrophobic film and the glass substrate by forming the stable covalent bonds. Its fundamental characteristics were tested and analyzed including transmittance, contact angle, micromorphology and energy spectrum. Finally, the effect of the superhydrophobic film on the self-cleaning performance and improvement of output power were investigated after coating the film on PV modules. The comparison results show that the prepared superhydrophobic thin film not only has anti-reflection and self-cleaning ability to improve the transmittance and output power of the PV modules, but also has excellent weatherability by forming stable covalent bonds through dehydration reactions.

Low-cost, universal light-harvesting coating layer for thin film solar cells by employing micro-prism films

Reduction of optical loss in thin-film solar cells, such as polymer solar cells and perovskite solar cells, is a key issue to promote device performance. A number of optical strategies have been investigated to enhance absorption. Among them, the light management layer provides an effective approach. This work designed and fabricated a micro-prism film with a simple technology. It significantly improved the light absorption of the solar cells after coating on the device incident windows. A specific optical model was built by combining ray optics and wave optics to explore the light trapping properties of the micro-prism films. Theoretically, the micro-prism film presented great anti-reflection ability. Its light trapping efficiency depended on the thickness periodically. However, within a wide thickness range in each period, the absorption enhancement remained at the maximum, which lowered the difficulties of thickness control in fabrication. Experimentally, coated with a micro-prism film, the JSC value of the polymer solar cells increases by 13.8%, leading to the power conversion efficiency (PCE) enhancing by 12.1%. On the other hand, perovskite solar cells with a thin active layer were prepared. JSC increased by 10.1% and PCE was enhanced by 6.0%, which were close to those of the device with a typical thick active layer. This also provided a physical way to reduce the heavy metal lead and lower environment pollution risk.

Antireflection Improvement and Junction Quality Optimization of Si/PEDOT:PSS Solar Cell with the Introduction of Dopamine@Graphene

Si/PEDOT: PSS solar cell is an optional photovoltaic device owing to its promising high photovoltaic conversion efficiency (PCE) and economic manufacture process. In this work, dopamine@graphene was firstly introduced between the silicon substrate and PEDOT:PSS film for Si/PEDOT: PSS solar cell. The dopamine@graphene was proved to be effective in improving the PCE, and the influence of mechanical properties of dopamine@graphene on solar cell performance was revealed. When dopamine@graphene was incorporated into the cell preparation, the antireflection ability of the cell was enhanced within the wavelength range of 300~450 and 650~1100 nm. The enhanced antireflection ability would benefit amount of the photon-generated carriers. The electrochemical impedance spectra test revealed that the introduction of dopamine@graphene could facilitate the separation of carriers and improve the junction quality. Thus, the short-circuit current density and fill factor were both promoted, which led to the improved PCE. Meanwhile, the influence of graphene concentration on device performances was also investigated. The photovoltaic conversion efficiency would be promoted from 11.06% to 13.15% when dopamine@graphene solution with concentration 1.5 mg/mL was applied. The achievements of this study showed that the dopamine@graphene composites could be an useful materials for high-performance Si/PEDOT:PSS solar cells.

Research on Shrinkage Chemical Properties of Cement Stabilized Macadam Material Based on a Multi-dimensional Expansion and Shrinkage Tester

In order to find out the shrinkage law of cement stabilized macadam material under specific conditions, this paper studied the expansion and shrinkage properties of cement stabilized macadam material under two environmental conditions, five kinds of cement dosage conditions, suspended compacted type and skeleton compaced type based on the multi-dimensional expansion and shrinkage tester. Through the test comparison, it is confirmed that the water loss rate of cement stabilized macadam material increases with the increase of cement dosage, showing a general change rule of rising first and then stabilizing. The average increase of the total water loss rate of suspended compacted cement stabilized macadam at room temperature was greater than that of the skeleton compacted cement stabilized macadam. The dry shrinkage strain also follows the above trend. Either at room temperature or under the conditions of dry shrinkage box, the water loss rate of suspended compacted cemeny stabilized macadam is higher than that of skeleton compacted cement stabilized macadam , which can be up to 3.23% higher. By comparing the temperature shrinkage coefficient under the high and low temperature environment, the temperature coefficient of the skeleton compacted cement stabilized macadam is smaller than that of the suspended compacted cement stabilized macadam. The temperature shrinkage coefficient of the suspended compacted cement stabilized macadam increases by 5.56% on average for each 0.5% increase of the cement dosage, and the temperature shrinkage coefficient of the skeleton compacted cement stabilized macadam increases by 6.33% on average. Through the comparative analysis of tests, it can be found that the anti-reflection crack ability of the skeleton compacted cement stabilized macadam material is better, and the fine aggregate content should be strictly controlled in the construction.

Nano-Texturing of Silicon Wafers Via One-Step Copper-Assisted Chemical Etching

Nano-texturing of a silicon surface has been achieved via one-step copper-assisted chemical etching (CACE), which offers a simple approach for large-scale production of inverted pyramid textured silicon surfaces. The effects of H2O2 concentration, etching time and reaction temperature on the inverted pyramid-like structure and anti-reflective ability were systematically investigated. The results show that the lowest average reflectivity (4.3%) in the wavelength range of 300~1000 nm was obtained under the optimum conditions of 0.06 mol/L copper nitrate, 3 mol/L H2O2 concentration and 2 mol/L hydrofluoric acid (HF) at 60 °C for 5 min. The formation mechanism of the inverted pyramid structure is discussed and can be attributed to the moderate catalytic activity of nanocopper particles that induce etching preferentially along the non- directions of the silicon. The inverted pyramid structures, with the excellent anti-reflectivity, have potential application in the fabrication of solar cells compatible with the semiconducting industry.