Fabrication of Rough Polymer Surfaces Exhibiting Anti-reflective Properties

2015 ◽  
Vol 1728 ◽  
Author(s):  
Srinadh Mattaparthi ◽  
Chandra S. Sharma
Keyword(s):  
Solar Cells ◽  
Soft Lithography ◽  
Electrospun Nanofibers ◽  
Polymer Surfaces ◽  
Large Area ◽  
Engineering Applications ◽  
Pdms Surface ◽  
Hierarchical Roughness ◽  
Vis Spectroscopy ◽  
Wide Range

ABSTRACTWe have demonstrated some facile ways to fabricate the large area polymer surfaces with varying roughness followed by studying their anti-reflective properties. One of the approaches is based on electrospun nanofibers deposited on a substrate in an uneven non-woven matrix. This electrospun fabric was used as a master template to fabricate the negative replica of the fibers by soft lithography generating the roughness in polydimethylsiloxane (PDMS) surfaces. The second approach is based on biomimicking of flower petals. Petals are used as a master template to transfer surface features with hierarchical roughness over PDMS surface using replica moulding. As fabricated polymer surfaces with varied roughness have then tested for their anti-reflective properties using UV-VIS spectroscopy over a wide range of wavelengths and angles of incidence of light. These measurements show near zero reflection of patterned PDMS surfaces as compared to planar PDMS. This omnidirectional broadband anti-reflection behaviour of polymer surfaces can be used in wide variety of engineering applications including in solar cells.

scholarly journals Polycarbonate Masters for Soft Lithography

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1392
Author(s):  
Filippo Amadeo ◽  
Prithviraj Mukherjee ◽  
Hua Gao ◽  
Jian Zhou ◽  
Ian Papautsky
Keyword(s):  
Soft Lithography ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Silicon Substrates ◽  
Large Area ◽  
Aspect Ratios ◽  
Rectangular Channels ◽  
Wide Range ◽  
Long Term Preservation

Fabrication of microfluidic devices by soft lithography is by far the most popular approach due to its simplicity and low cost. The approach relies on casting of elastomers, such as polydimethylsiloxane (PDMS), on masters fabricated from photoresists on silicon substrates. These masters, however, can be expensive, complicated to fabricate, and fragile. Here we describe an optimized replica molding approach to preserve the original masters by heat molding of polycarbonate (PC) sheets on PDMS molds. The process is faster and simpler than previously reported methods and does not result in a loss of resolution or aspect ratio for the features. The generated PC masters were used to successfully replicate a wide range of microfluidic devices, including rectangular channels with aspect ratios from 0.025 to 7.3, large area spiral channels, and micropost arrays with 5 µm spacing. Moreover, fabrication of rounded features, such as semi-spherical microwells, was possible and easy. Quantitative analysis of the replicated features showed variability of <2%. The approach is low cost, does not require cleanroom setting or hazardous chemicals, and is rapid and simple. The fabricated masters are rigid and survive numerous replication cycles. Moreover, damaged or missing masters can be easily replaced by reproduction from previously cast PDMS replicas. All of these advantages make the PC masters highly desirable for long-term preservation of soft lithography masters for microfluidic devices.

Fabrication and Characterization of Low-Cost, Large-Area Spray Deposited Cu2ZnSnS4 Thin Films for Heterojunction Solar Cells

2013 ◽  
Vol 1538 ◽  
pp. 115-121
Author(s):  
Sandip Das ◽  
Kelvin J. Zavalla ◽  
M. A. Mannan ◽  
Krishna C Mandal
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Spray Pyrolysis ◽  
Spray Pyrolysis Technique ◽  
Low Cost ◽  
Large Area ◽  
X Ray ◽  
Heterojunction Solar Cells ◽  
Vis Spectroscopy

ABSTRACTLarge-area Cu2ZnSnS4 (CZTS) thin films were deposited by low-cost spray pyrolysis technique on Mo-coated soda-lime glass (SLG) substrates at varied substrate temperatures of 563-703°K. Deposition conditions were optimized to obtain best quality films and effect of post deposition thermal processing of the as-deposited films under H2S ambient were investigated. Structural, morphological, and compositional characterization of as-deposited and H2S treated CZTS absorber layers were carried out by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX). Optical and electrical properties were measured by UV-Vis spectroscopy, van der Pauw, and Hall-effect measurements. Films grown at ∼360°C substrate temperature showed superior optoelectronic properties, improved stoichiometry and smoother morphology compared to films grown at much higher or lower temperatures. Film properties were significantly improved after the H2S processing. Our results show that large area high quality CZTS films can be fabricated by low-cost spray pyrolysis technique for high throughput commercial production of CZTS based heterojunction solar cells.

Efficiency of Solar Cells Based on Natural Dyes with Plasmonic Nanoparticle-Based Photo Anode

2018 ◽  
Vol 18 (06) ◽  
pp. 1850042
Author(s):  
Kirti Sahu ◽  
Mahesh Dhonde ◽  
V. V. S. Murty
Keyword(s):  
Solar Cells ◽  
Visible Region ◽  
Solar Spectrum ◽  
Visible Spectrum ◽  
Natural Dyes ◽  
Maximum Efficiency ◽  
Electromagnetic Spectrum ◽  
Synthetic Dyes ◽  
Vis Spectroscopy ◽  
Wide Range

Cheap and efficient dye sensitized solar cells (DSSCs) can be prepared using natural dyes responding in the visible region of solar spectrum. Localized surface plasmon resonance (LSPR) plays a very important role for the improvement in the efficiency of DSSCs by using Plasmonic nanoparticles (PNPs) for exploiting the visible portion of the solar radiation by transferring the energy from dye to PNP. This energy transfers from dye to semiconductor TiO2 through PNP which increases the overall photo catalytic activity. In the present study, Al-doped TiO2 photoanodes were prepared via sol–gel route and used for DSSC application. Various natural and synthetic dyes are prepared and the optical transmittance and absorbance of the dyes are measured in the wavelength range of 250–850[Formula: see text]nm using UV-Vis spectroscopy and they are used in DSSC. Natural dyes extracted from fruits and synthetic dye based on Ruthenium (Ru) metal complex is used as sensitizers. Power conversion efficiency (PCE) of solar cells utilizing different dyes is compared. Out of the various natural dyes, beetroot and strawberry extracts based dyes show good absorbance in the visible range of electromagnetic spectrum. On the other hand, synthetic dyes based on Ru complex show strong absorbance over a wide range of visible spectrum. The absorbance increases with increase in concentration of Ru in ethanol. The extracts of beetroot, strawberry and mixed fruits show a peak in absorbance spectra at 501nm, 416nm and 332nm, respectively, indicating the absorption over a wide range of visible spectrum. Maximum efficiency of DSSCs utilizing PNPs sensitized with beetroot and strawberry dyes are found to be 1.5% and 1.3%, respectively.

ТЕХНОЛОГИЯ И ПРИМЕНЕНИЕ ЭЛЕКТРОХИМИЧЕСКИХ ПРЕОБРАЗОВАТЕЛЕЙ

2020 ◽  
Vol 96 (3s) ◽  
pp. 450-455
Author(s):  
В.Г. Криштоп ◽  
Д.А. Жевненко ◽  
П.В. Дудкин ◽  
Е.С. Горнев ◽  
В.Г. Попов ◽  
...  
Keyword(s):  
Pressure Sensors ◽  
Engineering Applications ◽  
Electrochemical Systems ◽  
Seismic Sensors ◽  
Microelectronic Technology ◽  
Wide Range ◽  
Electrochemical Transducers ◽  
Element Base ◽  
New Devices

Электрохимические системы очень перспективны для разработки новой элементной базы для микроэлектроники и для использования в широком спектре инженерных задач. Мы разработали новую микроэлектронную технологию для изготовления электрохимических преобразователей (ЭХП) и новые приборы на основе новых электрохимических микроэлектронных чипов. Планарные электрохимические преобразователи могут использоваться в акселерометрах, сейсмических датчиках, датчиках вращения, гидрофонах и датчиках давления. Electrochemical systems are very promising for the development of a new element base for microelectronics, and for use in a wide range of engineering applications. We have developed a new microelectronic technology for manufacturing electrochemical transducers (ECP) and new devices based on new electrochemical microelectronic chips. Planar electrochemical transducers are used in accelerometers, seismic sensors, rotation sensors, hydrophones and pressure sensors.

A novel low cost texturization method for large area commercial mono-crystalline silicon solar cells

2006 ◽  
Vol 90 (20) ◽  
pp. 3557-3567 ◽  
Author(s):  
U. Gangopadhyay ◽  
K.H. Kim ◽  
S.K. Dhungel ◽  
U. Manna ◽  
P.K. Basu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Crystalline Silicon ◽  
Low Cost ◽  
Silicon Solar Cells ◽  
Large Area ◽  
Crystalline Silicon Solar Cells

scholarly journals One-step preparation of antimicrobial silicone materials based on PDMS and salicylic acid: insights from spatially and temporally resolved techniques

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Luca Barbieri ◽  
Ioritz Sorzabal Bellido ◽  
Alison J. Beckett ◽  
Ian A. Prior ◽  
Jo Fothergill ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Laser Scanning ◽  
Pathogenic Bacteria ◽  
Pharmaceutical Products ◽  
Laser Scanning Microscopy ◽  
Wound Dressings ◽  
Confocal Laser ◽  
Vis Spectroscopy ◽  
Wide Range ◽  
One Step

AbstractIn this work, we introduce a one-step strategy that is suitable for continuous flow manufacturing of antimicrobial PDMS materials. The process is based on the intrinsic capacity of PDMS to react to certain organic solvents, which enables the incorporation of antimicrobial actives such as salicylic acid (SA), which has been approved for use in humans within pharmaceutical products. By combining different spectroscopic and imaging techniques, we show that the surface properties of PDMS remain unaffected while high doses of the SA are loaded inside the PDMS matrix. The SA can be subsequently released under physiological conditions, delivering a strong antibacterial activity. Furthermore, encapsulation of SA inside the PDMS matrix ensured a diffusion-controlled release that was tracked by spatially resolved Raman spectroscopy, Attenuated Total Reflectance IR (ATR-IR), and UV-Vis spectroscopy. The biological activity of the new material was evaluated directly at the surface and in the planktonic state against model pathogenic bacteria, combining confocal laser scanning microscopy, electron microscopy, and cell viability assays. The results showed complete planktonic inhibition for clinically relevant strains of Staphylococcus aureus and Escherichia coli, and a reduction of up to 4 orders of magnitude for viable sessile cells, demonstrating the efficacy of these surfaces in preventing the initial stages of biofilm formation. Our approach adds a new option to existing strategies for the antimicrobial functionalisation of a wide range of products such as catheters, wound dressings and in-dwelling medical devices based on PDMS.

scholarly journals Application of Electrospun Nanofibers for Fabrication of Versatile and Highly Efficient Electrochemical Devices: A Review

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1741
Author(s):  
Seyedeh Nooshin Banitaba ◽  
Andrea Ehrmann
Keyword(s):  
Solar Cells ◽  
Fuel Cells ◽  
Electrochemical Sensors ◽  
Electrospun Nanofibers ◽  
Electrical Energy ◽  
High Specific Surface Area ◽  
Large Space ◽  
Electrolytic Cells ◽  
Research Areas ◽  
Electrochemical Devices

Electrochemical devices convert chemical reactions into electrical energy or, vice versa, electricity into a chemical reaction. While batteries, fuel cells, supercapacitors, solar cells, and sensors belong to the galvanic cells based on the first reaction, electrolytic cells are based on the reversed process and used to decompose chemical compounds by electrolysis. Especially fuel cells, using an electrochemical reaction of hydrogen with an oxidizing agent to produce electricity, and electrolytic cells, e.g., used to split water into hydrogen and oxygen, are of high interest in the ongoing search for production and storage of renewable energies. This review sheds light on recent developments in the area of electrospun electrochemical devices, new materials, techniques, and applications. Starting with a brief introduction into electrospinning, recent research dealing with electrolytic cells, batteries, fuel cells, supercapacitors, electrochemical solar cells, and electrochemical sensors is presented. The paper concentrates on the advantages of electrospun nanofiber mats for these applications which are mostly based on their high specific surface area and the possibility to tailor morphology and material properties during the spinning and post-treatment processes. It is shown that several research areas dealing with electrospun parts of electrochemical devices have already reached a broad state-of-the-art, while other research areas have large space for future investigations.

scholarly journals MXenes for future nanophotonic device applications

Nanophotonics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1831-1853
Author(s):  
Jaeho Jeon ◽  
Yajie Yang ◽  
Haeju Choi ◽  
Jin-Hong Park ◽  
Byoung Hun Lee ◽  
...  
Keyword(s):  
Solar Cells ◽  
Transition Metal ◽  
Wide Spectrum ◽  
Building Blocks ◽  
Optoelectronic Device ◽  
High Yield ◽  
Saturable Absorption ◽  
Nanophotonic Device ◽  
Wide Range ◽  
Device Applications

AbstractTwo-dimensional (2D) layers of transition metal carbides, nitrides, or carbonitrides, collectively referred to as MXenes, are considered as the new family of 2D materials for the development of functional building blocks for optoelectronic and photonic device applications. Their advantages are based on their unique and tunable electronic and optical properties, which depend on the modulation of transition metal elements or surface functional groups. In this paper, we have presented a comprehensive review of MXenes to suggest an insightful perspective on future nanophotonic and optoelectronic device applications based on advanced synthesis processes and theoretically predicted or experimentally verified material properties. Recently developed optoelectronic and photonic devices, such as photodetectors, solar cells, fiber lasers, and light-emitting diodes are summarized in this review. Wide-spectrum photodetection with high photoresponsivity, high-yield solar cells, and effective saturable absorption were achieved by exploiting different MXenes. Further, the great potential of MXenes as an electrode material is predicted with a controllable work function in a wide range (1.6–8 eV) and high conductivity (~104 S/cm), and their potential as active channel material by generating a tunable energy bandgap is likewise shown. MXene can provide new functional building blocks for future generation nanophotonic device applications.

scholarly journals The Growth of Semiconductor Thin Films Studied by RHEED

1990 ◽  
Vol 43 (5) ◽  
pp. 583
Author(s):  
GL Price
Keyword(s):  
Thin Films ◽  
Surface Science ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Large Area ◽  
Growth Modes ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Recent Developments

Recent developments in the growth of semiconductor thin films are reviewed. The emphasis is on growth by molecular beam epitaxy (MBE). Results obtained by reflection high energy electron diffraction (RHEED) are employed to describe the different kinds of growth processes and the types of materials which can be constructed. MBE is routinely capable of heterostructure growth to atomic precision with a wide range of materials including III-V, IV, II-VI semiconductors, metals, ceramics such as high Tc materials and organics. As the growth proceeds in ultra high vacuum, MBE can take advantage of surface science techniques such as Auger, RHEED and SIMS. RHEED is the essential in-situ probe since the final crystal quality is strongly dependent on the surface reconstruction during growth. RHEED can also be used to calibrate the growth rate, monitor growth kinetics, and distinguish between various growth modes. A major new area is lattice mismatched growth where attempts are being made to construct heterostructures between materials of different lattice constants such as GaAs on Si. Also described are the new techniques of migration enhanced epitaxy and tilted superlattice growth. Finally some comments are given On the means of preparing large area, thin samples for analysis by other techniques from MBE grown films using capping, etching and liftoff.

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