Antireflection Research Articles

A-Si/SiO2 nanolaminates for tuning the complex refractive index and band gap in optical interference coatings: publisher’s note

This publisher’s note reports corrections in Appl. Opt. 63, 1641 (2024)APOPAI0003-693510.1364/AO.515083.

Superhydrophilic antireflection films with excellent optical and mechanical performance for perovskite solar cells

SiO2-based antireflection (AR) films can obviously improve the transmittance of the glass cover on the solar cells. Nevertheless, it’s still challenging to fabricate SiO2 films in a facile way with great antireflective properties, high hardness and good weather resistance to ensure their long-term use in outdoor environments. To solve this problem, a double-layer broadband SiO2 antireflective film with high transmittance increase and excellent mechanical properties was successfully prepared via an acid-catalyzed sol–gel method using polyethylene glycol (PEG) as pore-forming agent. The porous PEG2000-modified SiO2 films were selected as the outer layer for coating onto the pure SiO2 film to form double-layer SiO2 films with graded refractive index. When the mass ratio of PEG2000 to TEOS was 40 %, the obtained film showed the highest transmittance increase of 3.03 % in the wavelength range of 380–1100 nm and a high hardness of 3H. After applied to the perovskite solar cell, a significant enhancement of 1.19 % in photoelectric conversion efficiency (PCE) was achieved compared to the solar cell covered with bare substrate. Furthermore, the water contact angle (WCA) was also reduced to 6° while that of pure SiO2 film was 51.3°, endowing the double-layer SiO2 film superhydrophilic and anti-fogging performance. After the weather resistance test, the transmittance loss of the film was only 0.38 %. Therefore, this work demonstrated that the use of an appropriate amount of pore-forming agent PEG and the double-layer graded refractive index structure can enhance the transmittance of acid-catalyzed SiO₂ films, while maintaining high hardness and good weathering resistance for perovskite solar cells.

Conformal TiO2 Aerogel-Like Films by Plasma Deposition: from Omniphobic Antireflective Coatings to Perovskite Solar Cell Photoelectrodes.

The ability to control the porosity of thin oxide films is a key factor determining their properties. Despite the abundance of dry processes for synthesizing oxide porous layers, a high porosity range is typically achieved by spin-coating-based wet chemical methods. Besides, special techniques such as supercritical drying are required to replace the pore liquid with air while maintaining the porous network. In this study, we propose a new method for the fabrication of ultraporous titanium dioxide thin films at room or mild temperatures (T ≤ 120 °C) by a sequential process involving plasma deposition and etching. These films are conformal to the substrate topography even for high-aspect-ratio substrates and show percolated porosity values above 85% that are comparable to those of advanced aerogels. The films deposited at room temperature are amorphous. However, they become partly crystalline at slightly higher temperatures, presenting a distribution of anatase clusters embedded in the sponge-like open porous structure. Surprisingly, the porous structure remains after annealing the films at 450 °C in air, which increases the fraction of embedded anatase nanocrystals. The films are antireflective, omniphobic, and photoactive, becoming superhydrophilic when subjected to ultraviolet light irradiation. The supported, percolated, and nanoporous structure can be used as an electron-conducting electrode in perovskite solar cells. The properties of the cells depend on the aerogel-like film thickness, which reaches efficiencies close to those of commercial mesoporous anatase electrodes. This generic solvent-free synthesis is scalable and applicable to ultrahigh porous conformal oxides of different compositions, with potential applications in photonics, optoelectronics, energy storage, and controlled wetting.

Damage regularity and multifractal analysis of sol-gel reflection coating of KDP crystal under low UV irradiation flux.

This study employed multifractal analysis to investigate the changes in surface morphology of SiO2 anti-reflective coatings prepared on KDP substrates using the sol-gel method, under various conditions of ultraviolet (UV) irradiance. The coatings were successfully fabricated, and the chemical structure of the SiO2 sol was comprehensively characterized using Solid-State Nuclear Magnetic Resonance (SSNMR) technology. Under low UV irradiance (4 J/cm2), repeated experiments revealed a crack-induced mechanism of surface fatigue damage. Utilizing Scanning Electron Microscopy (SEM), the study discovered the induction effect of initial crack defects in UV-damaged coatings and established a damage model. Furthermore, Atomic Force Microscopy (AFM) was used to acquire images of the coatings' surface morphology at different damage levels, which were analyzed using the multifractal spectrum f(α). This analysis confirmed the multifractal nature of the coatings both before and after damage. This study identified significant effects of UV irradiation on the width of the multifractal spectrum and Δf, indicating that the SiO2 anti-reflective coatings exhibit multifractal characteristics under various damage states. The coatings displayed a pattern of decreasing and then increasing singularity spectrum width, height distribution unevenness, and surface roughness with increasing damage. This study demonstrates that multifractal analysis is an effective tool for describing the complexity of the surface morphology of sol-gel-derived anti-reflective coatings for the first time and for validating their multifractal properties across different stages of UV damage. HIGHLIGHTS: Damage dynamic process of KDP crystal sol-gel coating was described by SEM&AFM; The crack propagation mechanism of sol-gel coating under UV radiation is proposed; The damage evolution of sol-gel coating was described by multifractal analysis.

First-principles insights into the structural, mechanical, electronic, optical, and thermophysical properties of XSrBr3 (X = Na, Ga, and Tl) perovskites: Implications for optoelectronic applications

Non-toxic halide perovskite compounds possess critical inherent and improved features for use in optoelectronic devices. The present work summarizes the physical properties of cubic halide perovskites XSrBr3 (X = Na, Ga, and Tl) based on first-principles theory. The structural, electrical, optical, mechanical, and thermophysical properties of these compounds are studied to assess their potential utility in optoelectronics field. GGA-PBE and GGA-PBEsol functionals were utilized to determine the lattice properties, cell volumes, and formation energies of the compounds. The negative formation energies support the compounds' structural stability. The compounds' bandgaps were computed using the GGA-PBE and Hybrid-HSE06 functionals. Each of the three compounds has a wide indirect bandgap. Optoelectronic devices such as UV detectors, solar panel antireflection coatings, OLED, QLED, and waveguides benefit from a greater static dielectric constant, broad absorption spectra, and low visible reflectance. The elastic stiffness constants Cij use the necessary conditions to demonstrate that the NaSrBr3, GaSrBr3, and TlSrBr3 perovskite structures are mechanically stable. The elastic modulus and other trustworthy properties imply that perovskites are mechanically ductile and soft. In conclusion, the investigation indicates the potential applications of these perovskite materials in photovoltaic and optoelectronic technologies.

Ion Implantation‐Induced Bandgap Modifications in the ALD TiO2 Thin Films

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%.

Antireflective Superhydrophobic and Robust Coating Based on Chitin Nanofibers and Methylsilanized Silica for Outdoor Applications.

Antireflective coatings with superhydrophobicity have many outdoor applications, such as solar photovoltaic panels and windshields. In this study, we fabricated an omnidirectional antireflective and superhydrophobic coating with good mechanical robustness and environmental durability via the spin coating technique. The coating consisted of a layer of phytic acid (PA)/polyacrylamide (PAM)/calcium ions (Ca2+) (referred to as Binder), an antireflective layer composed of chitin nanofibers (ChNFs), and a hydrophobic layer composed of methylsilanized silica (referred to as Mosil). The transmittance of a glass slide with the Binder/ChNFs/Mosil coating had a 5.2% gain at a wavelength of 550 nm, and the antireflective coating showed a water contact angle as high as 160° and a water sliding angle of 8°. The mechanical robustness and environmental durability of the coating, including resistance to peeling, dynamic impact, chemical erosion, ultraviolet (UV) irradiation, and high temperature, were evaluated. The coating retained excellent antireflective capacity and self-cleaning performance in the harsh conditions. The increase in voltage per unit area of a solar panel with a Binder/ChNFs/Mosil coating reached 0.4 mV/cm2 compared to the solar panel exposed to sunlight with an intensity of 54.3 × 103 lx. This work not only demonstrates that ChNFs can be used as raw materials to fabricate antireflective superhydrophobic coatings for outdoor applications but also provides a feasible and efficient approach to do so.

Hydrophobic antireflective coatings based on the synergistic effect of hollow and solid silica for application in photovoltaic modules

Photovoltaic glass coatings with multiple functions, such as strong broad-spectrum antireflectivity, effective self-cleaning, anti-abrasiveness, stability, and durability, have great potential for improving and ensuring the outdoor operation of photovoltaic modules. In this study, alkali-catalyzed hollow and solid silica nanoparticles were mixed at controlled ratios by sol-gel method, and the resulting solution was modified with HMDS to improve hydrophobicity, and obtain refractive indices ranging from 1.45 to 1.13. Subsequently, based on the principle of gradient refractive index, a trilayer hydrophobic antireflective (TLHA) coating was developed, comprising a top layer (n = 1.13), a middle layer (n = 1.27), and a bottom layer (n = 1.44). The TLHA coating exhibited an average transmittance of 97.77 % in the wavelength range of 380–1800 nm, with a peak transmittance of 98.97 % at 572 nm, and a hydrophobic contact angle of 144°. Additionally, after 144 h of thermal cycling and 600 abrasion cycles, the average transmittance of the TLHA coating decreased by 2.43 % and 1.63 %, respectively, in the 380–1800 nm range, and the coating's pencil hardness reached 5 H. And further application results showed that the crystalline silicon micro-modules with the TLHA coating could exhibit a 7.63 % and 5.24 % increase in Jsc, as calculated from EQE and J-V curves respectively, and a 5.34 % increase in PCE, compared to modules without the TLHA coating. These results highlight the extensive applicability of the TLHA coating in enhancing outdoor photovoltaic operation efficiency, durability, and wear resistance.

Highly flexible and transparent colorless polyimide substrate sandwiched between plasma polymerized fluorocarbon and InGaTiO for high performance flexible perovskite solar cells

ABSTRACT We integrated transparent antireflective coatings and transparent electrodes onto flexible colorless polyimide (CPI) substrates to fabricate high-performance flexible perovskite solar cells. Multifunctional PPFC/CPI/IGTO substrates were fabricated by sputtering the optimal plasma-polymerized fluorocarbon (PPFC) antireflective coating and InGaTiO (IGTO) electrode films on both sides of the CPI substrate. By applying PPFC with a low refractive index (1.38) as an antireflective coating, the transparency of the PPFC/CPI/IGTO substrate increased by an additional 1.2%. In addition, owing to the amorphous characteristics of the PPFC and IGTO layers, the PPFC/CPI/IGTO substrate showed constant sheet resistance and transmittance change even after 10,000 cycles during the bending tests. The flexible perovskite solar cells, fabricated on the PPFC/CPI/IGTO substrate, exhibited an increase in current density of 1.48 mA/cm2 after the deposition of the PPFC antireflective coating. These results confirmed that the PPFC/CPI/IGTO substrate was durable against high-temperature treatment, flexible, and exhibited excellent electrical characteristics. This enhanced the efficiency and durability of the flexible perovskite solar cells. Moreover, the hydrophobic PPFC layer allowed the self-cleaning of inflexible perovskite solar cells. Given these attributes, the PPFC/CPI/IGTO structure has been recognized as a good choice for multifunctional substrates of flexible perovskite solar cells, presenting the potential for enhancing performance.

Highly transparent and stable luminescent films with stable europium (III) complex Assisted with anti-Reflective coating

Rare earth complex polymer luminescent materials have important practical application value in organic electroluminescence, fluorescence sensing, solar cells and other fields. Herein, we fabricated the luminescent film (recorded as Eu (2 mCND)4Na/PMMA@LF) through doped Eu (2 mCND)4Na complex with polymethyl methacrylate (PMMA) followed by coating on a PMMA slab. And the antireflective (AR) coatings prepared with acid-catalyzed silica sol (ACSS) and base-catalyzed silica sol (BCSS) were coated on the surface of Eu (2 mCND)4Na/PMMA@LF which enhance its transparency increasing from 92 % to 98.7 %. This is because that the AR coatings have high transmittance and environmental stability. In addition, the luminescent film coated with antireflective coating displays high photo-stability, which was also demonstrated after a 35 h UV LED (∼200 mW/cm2) irradiation. The configuration of luminescent film with anti-reflection performance provides a scalable alternative to the current approaches for creating highly transparent solar windows.

Effects of Nano-Dome and Nano-Cone Anti-reflective Coating Arrays in Enhancement of Light Extraction on Organic Light-Emitting Diodes

Effects of Nano-Dome and Nano-Cone Anti-reflective Coating Arrays in Enhancement of Light Extraction on Organic Light-Emitting Diodes

Mechanically robust and self-cleaning antireflective coatings for photovoltaic modules

As the conversion efficiency of solar cells approaches its theoretical upper limit, the importance of photon management in enhancing photovoltaic modules performance becomes paramount. One promising approach involves the application of antireflective coatings to the surface of the photovoltaic glass to improve its transmittance. However, balancing mechanical durability, self-cleaning characteristics, and optical performance for photovoltaic applications remains challenging. This study focuses on synthesizing a composite coating through the sol-gel method, aiming to achieve high optical transmittance and superior mechanical properties. Hollow silica nanoparticles (HSN) are employed to achieve a reduced refractive index, while a composite sol of zirconium dioxide (ZrO2) and titania (TiO2) is utilized to enhance mechanical strength and hydrophilicity. The prepared composite coatings demonstrate notable improvements, with the photovoltaic transmittance (TPV) increasing from 88.31 % to 94.03 % in the 300–1100 nm wavelength range, with peak transmittance reaching 98.01 %. Additionally, the coatings exhibited a pencil hardness rating of 3H alongside exceptional abrasion resistance, affirming their potential for enduring practical deployment. When compared to uncoated glass, modules integrated with these composite coatings showed a significant increase in short-circuit current density (JSC) by 1.28 mA cm-2 and in photoelectric conversion efficiency (PCE) by 0.70 %. These results highlight the composite coatings' capacity to enhance the conversion efficiency of photovoltaic modules significantly. By attempting to prepare anti reflective coatings with high mechanical strength and self-cleaning properties, this study is expected to make a valuable contribution to the advancement of sustainable and durable solar cell technology.

Assembly of functional carboxymethyl cellulose/polyethylene oxide/anatase TiO2 nanocomposites and tuning the dielectric relaxation, optical, and photoluminescence performances

Nanocomposite films consisting of carboxymethyl cellulose, polyethylene oxide (CMC/PEO), and anatase titanium dioxide (TO) were produced by the use of sol-gel and solution casting techniques. TiO2 nanocrystals were effectively incorporated into CMC/PEO polymers, as shown by X-ray diffraction (XRD) and attenuated total reflectance fourier transform infrared (ATR-FTIR) analysis. The roughness growth is at high levels of TO nanocrystals (TO NCs), which means increasing active sites and defects in CMC/PEO. In differential scanning calorimetry (DSC) thermograms, the change in glass transition temperature (T g) values verifies that the polymer blend interacts with TO NCs. The increment proportions of TO NCs have a notable impact on the dielectric performances of the nanocomposites, as observed. The electrical properties of the CMC/PEO/TO nanocomposite undergo significant changes. The nanocomposite films exhibit a red alteration in the absorption edge as the concentration of TO NCs increases in the polymer blend. The decline in the energy gap is readily apparent as the weight percentage of TO NCs increases. The photoluminescence (PL) emission spectra indicate that the sites of the luminescence peak maximums show slight variation; peaks get wider, while their intensities decrease dramatically as the concentration of TO increases. These nanocomposite materials show potential for multifunctional applications including optoelectronics, antireflection coatings, photocatalysis, light emitting diodes, and solid polymer electrolytes.

Polymer-like hydrogenated amorphous carbon thin films fabricated by plasma-enhanced chemical vapor deposition of cyclohexane precursor

Hydrogenated amorphous carbon (a-C:H) films were fabricated by plasma-enhanced chemical vapor deposition (PECVD) of a cyclohexane precursor at ambient temperature at varying deposition pressures from 19.73 to 38.00 Pa and varying plasma powers from 20 to 80 W. The deposition rate of the a-C:H films was strongly dependent on the deposition conditions. The films were all optically transparent with extinction coefficient below 0.0042. The refractive index as an indicator of the film's density varied depending on the deposition conditions. Their surfaces were all hydrophobic regardless of the deposition conditions. The a-C:H films had wide optical bandgaps ranging from 3.09 to 3.69 eV. The refractive index and FTIR spectra were consistent with those of polymer-like a-C:H films. As the deposition pressure decreased and plasma power increased, the intensity of a dominant peak of CHx stretching mode in the FTIR spectra decreased. The relative hydrogen content of the a-C:H films was estimated from an FTIR analysis and determined to have an inverse relationship with refractive index. These results indicated that the formation of more energetic plasmas during deposition at lower pressures and higher plasma powers led to the a-C:H films with reduced hydrogen content and increased density. The observed film properties could be advantageous for several applications, particularly as protective, wear-resistant, low-friction, or anti-reflective coatings for optical windows.

Growth rate of AL2O3 Thin Film by Liquid Phase Deposition as an Anti-reflection Coating Layer on Crystalline Silicon for Solar Cell Applications

The fabrication of photovoltaic (PV) device requires that surface reflectance of solar cells has to be minimized to achieve higher photo-conversion efficiency (PCE). Antireflection coating layer is deposited on the surface of a p-type crystalline silicon material to reduce the surface reflections of solar radiation and increase its absorption for efficient solar cell application. In this work, aluminum oxide thin film by liquid phase deposition (LPD-Al2O­3) is synthesized from combined solution of aluminum sulfate octadecahydrate (Al2(SO4)3·18H2­O) and sodium carbonate (NaHCO3) with pH of 3.1. Some samples of p-type (100) crystalline silicon (c-Si) wafers of resistivity 1 – 10 mΩ were immersed inside the growth liquid of LPD-Al2O­3 thin film for 1hr – 2.5 hours. This is followed by annealing the samples at a temperature of 450oC, the deposition rate is faster in the range 1 – 1.5 hours is about 35nm/hr. As the growth time increases, the growth rate of the film decreases and remains nearly constant at about 10 nm/hour at 1 – 2 hours. When the growth time exceeds 2 hours, the film thickness remains unchanged showing that the liquid has lost in growth ability. The weighted average reflection (%) of planar c-Si is reduced from 44.9 % to 29.6 % after deposition of the LPD-Al2O­3 for 2.5 hours growth time, indicating a 34.1 % reduction in reflection within wavelength region of 300–1100 nm. While the root means square (RMS) surface roughness of 36.5 nm was also recorded at the highest growth time of 2.5 hours. This shows the effect of thicker LPD-Al2O­3 thin film layer increases the anti-reflecting coating property of the material.

Growth rate of AL2O3 Thin Film by Liquid Phase Deposition as an Anti-reflection Coating Layer on Crystalline Silicon for Solar Cell Applications

The fabrication of photovoltaic (PV) device requires that surface reflectance of solar cells has to be minimized to achieve higher photo-conversion efficiency (PCE). Antireflection coating layer is deposited on the surface of a p-type crystalline silicon material to reduce the surface reflections of solar radiation and increase its absorption for efficient solar cell application. In this work, aluminum oxide thin film by liquid phase deposition (LPD-Al2O­3) is synthesized from combined solution of aluminum sulfate octadecahydrate (Al2(SO4)3·18H2­O) and sodium carbonate (NaHCO3) with pH of 3.1. Some samples of p-type (100) crystalline silicon (c-Si) wafers of resistivity 1 – 10 mΩ were immersed inside the growth liquid of LPD-Al2O­3 thin film for 1hr – 2.5 hours. This is followed by annealing the samples at a temperature of 450oC, the deposition rate is faster in the range 1 – 1.5 hours is about 35nm/hr. As the growth time increases, the growth rate of the film decreases and remains nearly constant at about 10 nm/hour at 1 – 2 hours. When the growth time exceeds 2 hours, the film thickness remains unchanged showing that the liquid has lost in growth ability. The weighted average reflection (%) of planar c-Si is reduced from 44.9 % to 29.6 % after deposition of the LPD-Al2O­3 for 2.5 hours growth time, indicating a 34.1 % reduction in reflection within wavelength region of 300–1100 nm. While the root means square (RMS) surface roughness of 36.5 nm was also recorded at the highest growth time of 2.5 hours. This shows the effect of thicker LPD-Al2O­3 thin film layer increases the anti-reflecting coating property of the material.

A highly efficient, eco‐friendly method for antireflection nanostructures on poly (ethylene terephthalate)

AbstractAntireflection 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.

Upright Pyramid Surface Textures for Light Trapping and MoOx Layer in Ultrathin Crystalline Silicon Solar Cells

In this work, ray tracing is used to investigate the optical characteristics of various surface structures in ultrathin crystalline silicon (c-Si) for solar cells. Ultrathin c-Si with a thickness of 20 μm is used as the substrate. The light trapping includes front upright pyramids with a molybdenum oxides (MoOx) anti-reflection (AR) layer. Planar ultrathin c-Si (without a MoOx AR layer and upright pyramids) is used as a reference. The wafer ray tracer was developed by a photovoltaic (PV) lighthouse to model the MoOx AR layer to reduce the front surface reflectance and impacts of the AR layer on ultrathin Si solar cells. The optical properties are calculated on the AM1.5 global solar energy spectrum across the 200–1200 nm wavelength region. From the absorbance profile, the photogenerated current density (Jph) in the substrate is also calculated with various surface structures. The front upright pyramids with the MoOx layer result in the largest absorbance enhancement due to the enhanced light scattering by the pyramids and MoOx AR layer. The Jph of 37.41 mA/cm2 is improved when compared to the planar ultrathin c-Si reference. This study is significant as it illustrates the potential of ultrathin c-Si as a promising PV module technology in the future.

Optical modeling of systematic uncertainties in detector polarization angles for the Atacama Cosmology Telescope

We present an estimate of the Atacama Cosmology Telescope (ACT) detector polarization angle systematic uncertainty from optics perturbation analysis using polarization-sensitive ray tracing in CODE V optical design software. Uncertainties in polarization angle calibration in CMB measurements can limit constraints on cosmic birefringence and other cosmological parameters sensitive to polarization leakage. Our framework estimates the angle calibration systematic uncertainties from possible displacements in lens positions and orientations, and anti-reflection coating (ARC) thicknesses and refractive indices. With millimeter displacements in lens positions and percent-level perturbations in ARC thicknesses and indices from design, we find the total systematic uncertainty for three ACT detector arrays operating between 90 and 220 GHz to be at the 10th of degree scale. Reduced lens position and orientation uncertainties from physical measurements could lead to a reduction in the systematic uncertainty estimated with the framework presented here. This optical modeling may inform polarization angle systematic uncertainties for current and future microwave polarimeters, such as the CCAT Observatory, Simons Observatory, and CMB-S4.

Fabrication and characterization of MgF2 anti-reflective films comprising dual-layer prepared by physical vapor deposition technique for optoelectronic applications

Moth eye protuberances, for instance, exhibit highly developed and well-organized nanostructures that allow them to adapt to a wide range of environmental conditions and achieve remarkable antireflective performance, which has inspired and been emulated by scientific advancement. Innovative studies have focused on bioinspired and imitating moth-eye patterns to provide a textured surface in multilayer antireflective coatings (ARC) using nanomaterials, polymers, or composites to eliminate undesired reflection in standard optical components and optoelectronic industrial applications. Multilayer AR systems provide a number of advantages over single-layer designs. Still, their limited applicability is due to obstacles such as mismatched properties at interfaces, high costs, poor mechanical durability, and wetting concerns. Using MgF2 and polytetrafluoroethylene, we develop a technique for fabricating high-performance AR nanostructures on borosilicate crown glass and Fluorine-doped Tin Oxide substrates via the glancing angle deposition technique. By inducing porosity and changing the deposition angle (α) at 550 nm, the refractive index of MgF2 is reduced from 1.38 to 1.14. In agreement with optical modelling predictions, high-performance ARC has been successfully produced on different substrates. Besides this, introducing a thin layer of polytetrafluoroethylene on MgF2 ARC via vapor deposition having a refractive index of 1.21 deposited at α ∼80° results in inducing water-repellent properties in ARC. Hence, our fabricated ARC yields stable AR efficiency with outstanding directional uniformity, durability, and negative temperature stability, having hydrophobic characteristics.