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Peng Jiang – One of the best experts on this subject based on the ideXlab platform.
self assembled nanoparticle Antireflection Coatings on geometrically complex optical surfacesOptics Letters, 2018Co-Authors: Khalid Askar, Bin Jiang, Calen J Leverant, Jiamin Wang, Christopher Kim, Peng JiangAbstract:
Here we report a simple and scalable electrostatics-assisted colloidal self-assembly technology for fabricating monolayer nanoparticle Antireflection Coatings on geometrically complex optical surfaces. By using a surface-modified glass volumetric flask with a long neck as a proof-of-concept demonstration, negatively charged silica nanoparticles with 110 nm diameter are electrostatically adsorbed on both the interior and exterior surfaces of the flask possessing positive surface charges. The self-assembled monolayer nanoparticle Antireflection Coatings can significantly improve light transmission through different regions of the flask with varied curvatures, as revealed by optical transmission measurements and numerical simulations using a simplified thin-film multilayer model.
bioinspired self cleaning Antireflection CoatingsAdvanced Materials, 2008Co-Authors: I Jiang, Peng JiangAbstract:
Millions of years before we began to generate functional nanostructures, biological systems were using nanometer-scale architectures to produce unique functionalities. For instance, moths use hexagonal arrays of nonclose-packed (ncp) nipples as Antireflection Coatings (ARCs) to reduce reflectivity from their compound eyes. The outer surface of the corneal lenses of moths consists of ncp arrays of conical protuberances, termed corneal nipples, typically of sub-300 nm height and spacing. These arrays of subwavelength nipples generate a graded transition of refractive index, leading to minimized reflection over a broad range of wavelengths and angles of incidence. Similar periodic arrays of ncp pillars have also been observed on the wings of cicada to render superhydrophobic surfaces for self-cleaning functionality. In this Communication, we report a simple and scalable bioinspired templating technique for fabricating broadband and superhydrophobic ARCs on technologically important silicon and glass substrates. Crystalline silicon is the most important material for solar cells. Unfortunately, due to the high refractive index of silicon, more than 30% of incident light is reflected back from the surface of crystalline silicon. ARCs are therefore widely utilized to reduce the unwanted reflective losses. Quarterwavelength silicon nitride (SiNx) films deposited by plasmaenhanced chemical vapor deposition (PECVD) are the industrial standard for ARCs on crystalline silicon substrates. However, the PECVD-deposited SiNx films are expensive to fabricate. Additionally, commercial SiNx ARCs are typically designed to suppress reflection efficiently at wavelengths around 600 nm. The reflective loss is rapidly increased for near-infrared and other visible wavelengths, which contain a large portion of the incident solar energy. In contrast, subwavelength-structured moth-eye ARCs directly patterned in the substrates are broadband and intrinsically more stable and durable than multilayer ARCs since no foreign material is involved. Nevertheless, current topdown lithographic technologies in creating subwavelength
broadband moth eye Antireflection Coatings on siliconApplied Physics Letters, 2008Co-Authors: Peng Jiang, I JiangAbstract:
We report a bioinspired templating technique for fabricating broadband Antireflection Coatings that mimic antireflective moth eyes. Wafer-scale, subwavelength-structured nipple arrays are directly patterned on silicon using spin-coated silica colloidal monolayers as etching masks. The templated gratings exhibit excellent broadband Antireflection properties and the normal-incidence specular reflection matches with the theoretical prediction using a rigorous coupled-wave analysis (RCWA) model. We further demonstrate that two common simulation methods, RCWA and thin-film multilayer models, generate almost identical prediction for the templated nipple arrays. This simple bottom-up technique is compatible with standard microfabrication, promising for reducing the manufacturing cost of crystalline silicon solar cells.
Fangting Chi – One of the best experts on this subject based on the ideXlab platform.
mechanically robust and self cleaning Antireflection Coatings from nanoscale binding of hydrophobic silica nanoparticlesSolar Energy Materials and Solar Cells, 2019Co-Authors: Fangting Chi, Dejian Liu, Jiehong LeiAbstract:
Abstract Antireflection Coatings from silica nanoparticles exhibit promising applications in many energy-related areas such as solar-thermal and photo-voltaic systems. However, the Coatings suffer from poor mechanical durability and low self-cleaning capability in outdoor conditions, which limit their practical application. Here, we create mechanically robust and self-cleaning Antireflection Coatings through nanoscale binding of hydrophobic silica nanoparticles with an organosilica binder. The Coatings demonstrated nearly full transmission at desired wavelength of ∼550 nm, with peak transmittance up to 99.9%. Further advantage of these Coatings is the combination of hydrophobic silica nanoparticles with the organosilica binder, resulting in hydrophobic and mechanically robust Coatings, with water contact angle of 161° and hardness of 4.2 GPa. The Coatings maintained their high transmittance under outdoor conditions for 3 months, which is largely attributed to their self-cleaning functionality resulting from super-hydrophobicity. We envision that the mechanically robust and self-cleaning Antireflection Coatings could find wide applications in outdoor conditions and other harsh environments.
Synthesis of ultrasmall silica nanoparticles for application as deep-ultraviolet Antireflection CoatingsApplied Surface Science, 2017Co-Authors: Xiaonan Liu, Pan Wen, Xiaoyan Shu, Fangting ChiAbstract:
Abstract Ultrasmall silica nanoparticles with controllable size were prepared by a modified Stober method. In the method, the size of the nanoparticles can be decreased to 4.8 nm by addition of Triton X-100 into the reactants combined by controlling the ammonia concentrations. The ultrasmall silica nanoparticles modified with Triton X-100 can be well deposited onto optical substrates, resulting in the formation of deep-ultraviolet Antireflection Coatings. The Antireflection Coatings demonstrated transmittance as high as 99.92% in the deep-ultraviolet band, suggesting that nearly the whole light is transmitted through the optics. These Antireflection Coatings will be used in deep-ultraviolet optical system such as high-peak-power laser system and photolithography.
David J. Poxson – One of the best experts on this subject based on the ideXlab platform.
Development of Nanostructured Antireflection Coatings for EO/IR Sensor and Solar Cell ApplicationsMaterials Sciences and Applications, 2012Co-Authors: Ashok K. Sood, David J. Poxson, E. Fred Schubert, Xing Yan, Roger E. Welser, Jaehee Cho, Gopal G. Pethuraja, Yash R. Puri, Adam W. Sood, Nibir K. DharAbstract:
Electro-optical/infrared (EO/IR) sensors and photovoltaic power sources are being developed for a variety of defense and commercial applications. One of the critical technologies that will enhance both EO/IR sensor and photovoltaic module performance is the development of high quality nanostructure-based Antireflection Coatings. In this paper, we review our work on advanced Antireflection structures that have been designed by using a genetic algorithm and fabricated by using oblique angle deposition. The Antireflection Coatings are designed for the wavelength range of 250 nm to 2500 nm and an incidence angle between 00 and 400. These nanostructured Antireflection Coatings are shown to enhance the optical transmission through transparent windows over a wide band of interest and minimize broadband reflection losses to less than one percent, a substantial improvement over conventional thin-film Antireflection coating technologies.
High-performance Antireflection Coatings utilizing nanoporous layersMRS Bulletin, 2011Co-Authors: David J. Poxson, Mei-ling Kuo, Frank W. Mont, Y.-s. Kim, Xing Yan, Roger E. Welser, Ashok K. Sood, Jaehee Cho, Shawn-yu Lin, E. Fred SchubertAbstract:
To harness the full spectrum of solar energy, optical reflections at the surface of a solar photovoltaic cell must be reduced as much as possible over the relevant solar spectral range and over a wide range of incident angles. The development of Antireflection Coatings embodying omni-directionality over a wide range of wavelengths is challenging. Recently, nanoporous films, fabricated by oblique-angle deposition and having tailored- and very low-refractive index properties, have been demonstrated. Tailorability of the refractive index and the ability to realize films with a very low-refractive index are properties critical in the performance of broadband, omnidirectional Antireflection Coatings. As such, nanoporous materials are ideally suited for developing near-perfect Antireflection Coatings. Here, we discuss multilayer Antireflection Coatings with near-perfect transmittance over the spectral range of 400−2000 nm and over widely varying angles of acceptance, 0−90°. The calculated solar optical-to-electrical efficiency enhancement that can be attained with nanoporous multilayer Coatings over single-layer quarter-wave films is 18%, making these Coatings highly attractive for solar cell applications.
Performance of Antireflection Coatings Consisting of Multiple Discrete Layers and Comparison with Continuously Graded Antireflection CoatingsApplied Physics Express, 2010Co-Authors: Martin F. Schubert, David J. Poxson, Frank W. Mont, Jong Kyu Kim, E. Fred SchubertAbstract:
The performance of discrete multilayer and continuously graded Antireflection Coatings for omnidirectional broadband applications are compared. It is shown that in practical cases where refractive index choices are constrained, discrete Antireflection Coatings can surpass the performance of continuously graded Coatings by taking advantage of interference effects, which continuously graded Coatings are expressly designed to avoid. A four-layer Antireflection coating designed using a genetic algorithm is fabricated, and is experimentally shown to have reflectivity lower than what is achievable for continuously graded designs.