Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film

PubMed Central

Gotanda, Tatsuhiro; Katsuda, Toshizo; Gotanda, Rumi; Kuwano, Tadao; Akagawa, Takuya; Tanki, Nobuyoshi; Tabuchi, Akihiko; Shimono, Tetsunori; Kawaji, Yasuyuki

2016-01-01

Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were −32.336 and −33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range. PMID:28144120

Proximity effect assisted absorption enhancement in thin film with locally clustered nanoholes.

PubMed

Wu, Shaolong; Zhang, Cheng; Li, Xiaofeng; Zhan, Yaohui

2015-03-01

We focus on the light-trapping characteristics of a thin film with locally clustered nanoholes (NHs), considering that the clustering effect is usually encountered in preparing the nanostructures. Our full-wave finite-element simulation indicates that an intentionally introduced clustering effect could be employed for improving the light-trapping performance of the nanostructured thin film. For a 100 nm thick amorphous silicon film, an optimal clustering design with NH diameter of 100 nm is able to double the integrated optical absorption over the solar spectrum, compared to the planar counterpart, as well as show much improved optical performance over that of the nonclustered setup. A further insight into the underlying physics explains the outstanding light-trapping capability in terms of the increased available modes, a stronger power coupling efficiency, a higher fraction of electric field concentrated in absorbable material, and a higher density of photon states.

Parasitic oscillation suppression in solid state lasers using absorbing thin films

DOEpatents

Zapata, L.E.

1994-08-02

A thin absorbing film is bonded onto at least certain surfaces of a solid state laser gain medium. An absorbing metal-dielectric multilayer film is optimized for a broad range of incidence angles, and is resistant to the corrosive/erosive effects of a coolant such as water, used in the forced convection cooling of the film. Parasitic oscillations hamper the operation of solid state lasers by causing the decay of stored energy to amplified rays trapped within the gain medium by total and partial internal reflections off the gain medium facets. Zigzag lasers intended for high average power operation require the ASE absorber. 16 figs.

Parasitic oscillation suppression in solid state lasers using absorbing thin films

DOEpatents

Zapata, Luis E.

1994-01-01

A thin absorbing film is bonded onto at least certain surfaces of a solid state laser gain medium. An absorbing metal-dielectric multilayer film is optimized for a broad range of incidence angles, and is resistant to the corrosive/erosive effects of a coolant such as water, used in the forced convection cooling of the film. Parasitic oscillations hamper the operation of solid state lasers by causing the decay of stored energy to amplified rays trapped within the gain medium by total and partial internal reflections off the gain medium facets. Zigzag lasers intended for high average power operation require the ASE absorber.

Absorbing film assisted laser induced forward transfer of fungi (Trichoderma conidia)

NASA Astrophysics Data System (ADS)

Hopp, B.; Smausz, T.; Antal, Zs.; Kresz, N.; Bor, Zs.; Chrisey, D.

2004-09-01

We present an investigation on absorbing film assisted laser induced forward transfer (AFA-LIFT) of fungus (Trichoderma) conidia. A KrF excimer laser beam [λ =248nm,FWHM=30ns (FWHM, full width at half maximum)] was directed through a quartz plate and focused onto its silver coated surface where conidia of the Trichoderma strain were uniformly spread. The laser fluence was varied in the range of 0-2600mJ/cm2 and each laser pulse transferred a pixel of target material. The average irradiated area was 8×10-2mm2. After the transfer procedure, the yeast extract medium covered glass slide and the transferred conidia patterns were incubated for 20 h and then observed using an optical microscope. The transferred conidia pixels were germinated and the areas of the culture medium surfaces covered by the pixels were evaluated as a function of laser fluence. As the laser fluence was increased from 0 to 355mJ/cm2 the transferred and germinated pixel area increased from 0 to 0.25mm2. Further increase in fluence resulted in a drastic decrease down to an approximately constant value of 0.06mm2. The yield of successful transfer by AFA-LIFT and germination was as much as 75% at 355mJ/cm2. The results prove that AFA-LIFT can successfully be applied for the controlled transfer of biological objects.

Mo0.5W0.5S2 for Q-switched pulse generation in ytterbium-doped fiber laser.

PubMed

Wang, Junli; Chen, Lei; Dou, Chenxi; Yan, Haiting; Meng, Lingjie; Wei, Zhiyi

2018-06-01

In this work, we fabricate the Mo 0.5 W 0.5 S 2 by microwave-assisted solvothermal method, and report the Q-switched Yb-doped fiber lasers (YDFL) using Mo 0.5 W 0.5 S 2 polymer film and tapered fiber as the saturable absorbers (SAs). The modulation depth and saturable intensity of the film SA are 5.63% and 6.82 MW cm -2 . The shortest pulse duration and the maximum single pulse energy are 1.22 μs and 148.8 nJ for the film SA, 1.46 μs and 339 nJ for the fiber-taper SA. To the best of our knowledge, this is the first report on the Q-switched YDFL using Mo 0.5 W 0.5 S 2 SAs.

Mo0.5W0.5S2 for Q-switched pulse generation in ytterbium-doped fiber laser

NASA Astrophysics Data System (ADS)

Wang, Junli; Chen, Lei; Dou, Chenxi; Yan, Haiting; Meng, Lingjie; Wei, Zhiyi

2018-06-01

In this work, we fabricate the Mo0.5W0.5S2 by microwave-assisted solvothermal method, and report the Q-switched Yb-doped fiber lasers (YDFL) using Mo0.5W0.5S2 polymer film and tapered fiber as the saturable absorbers (SAs). The modulation depth and saturable intensity of the film SA are 5.63% and 6.82 MW cm‑2. The shortest pulse duration and the maximum single pulse energy are 1.22 μs and 148.8 nJ for the film SA, 1.46 μs and 339 nJ for the fiber-taper SA. To the best of our knowledge, this is the first report on the Q-switched YDFL using Mo0.5W0.5S2 SAs.

Simultaneous fabrication of a microcavity absorber-emitter on a Ni-W alloy film

NASA Astrophysics Data System (ADS)

Nashun; Kagimoto, Masahiro; Iwami, Kentaro; Umeda, Norihiro

2017-10-01

A process for the simultaneous fabrication of microcavity structures on both sides of a film was proposed and demonstrated to develop a free-standing-type integrated absorber-emitter for use in solar thermophotovoltaic power generation systems. The absorber-emitter-integrated film comprised a heat-resistant Ni-W alloy deposited by electroplating. A two-step silicon mould was fabricated using deep reactive-ion etching and electron beam lithography. Cavity arrays with different unit sizes were successfully fabricated on both sides of the film; these arrays are suitable for use as a solar spectrum absorber and an infrared-selective emitter. Their emissivity spectra were characterised through UV-vis-NIR and Fourier transform infrared spectroscopy.

Metamaterial Perfect Absorber Analyzed by a Meta-Cavity Model Consisting of Multilayer Metasurfaces (Postprint)

DTIC Science & Technology

2017-09-05

metamaterial perfect absorber behaves as a meta-cavity bounded between a resonant metasurface and a metallic thin- film reflector. The perfect absorption...cavity quantum electrodynamics devices. 15. SUBJECT TERMS Metamaterial; meta-cavity; metallic thin- film reflector; Fabry-Perot cavity resonance...metamaterial perfect absorber behaves as a meta-cavity bounded between a resonant metasurface and a metallic thin- film reflector. The perfect absorption is

Interfacial Redox Reactions Associated Ionic Transport in Oxide-Based Memories.

PubMed

Younis, Adnan; Chu, Dewei; Shah, Abdul Hadi; Du, Haiwei; Li, Sean

2017-01-18

As an alternative to transistor-based flash memories, redox reactions mediated resistive switches are considered as the most promising next-generation nonvolatile memories that combine the advantages of a simple metal/solid electrolyte (insulator)/metal structure, high scalability, low power consumption, and fast processing. For cation-based memories, the unavailability of in-built mobile cations in many solid electrolytes/insulators (e.g., Ta 2 O 5 , SiO 2 , etc.) instigates the essential role of absorbed water in films to keep electroneutrality for redox reactions at counter electrodes. Herein, we demonstrate electrochemical characteristics (oxidation/reduction reactions) of active electrodes (Ag and Cu) at the electrode/electrolyte interface and their subsequent ions transportation in Fe 3 O 4 film by means of cyclic voltammetry measurements. By posing positive potentials on Ag/Cu active electrodes, Ag preferentially oxidized to Ag + , while Cu prefers to oxidize into Cu 2+ first, followed by Cu/Cu + oxidation. By sweeping the reverse potential, the oxidized ions can be subsequently reduced at the counter electrode. The results presented here provide a detailed understanding of the resistive switching phenomenon in Fe 3 O 4 -based memory cells. The results were further discussed on the basis of electrochemically assisted cations diffusions in the presence of absorbed surface water molecules in the film.

Solar collector

DOEpatents

Wilhelm, W.G.

The invention pertains to a flat plate collector that employs high performance thin films. The solar collector of this invention overcomes several problems in this field, such as excessive hardware, cost and reliability, and other prior art drawbacks outlined in the specification. In the preferred form, the apparatus features a substantially rigid planar frame. A thin film window is bonded to one planar side of the frame. An absorber of laminate construction is comprised of two thin film layers that are sealed perimetrically. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. Absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

Thin-film solar cell fabricated on a flexible metallic substrate

DOEpatents

Tuttle, John R.; Noufi, Rommel; Hasoon, Falah S.

2006-05-30

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate

DOEpatents

Tuttle, J. R.; Noufi, R.; Hasoon, F. S.

2006-05-30

A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

Nanostructured light-absorbing crystalline CuIn(1-x)GaxSe2 thin films grown through high flux, low energy ion irradiation

NASA Astrophysics Data System (ADS)

Hall, Allen J.; Hebert, Damon; Shah, Amish B.; Bettge, Martin; Rockett, Angus A.

2013-10-01

A hybrid effusion/sputtering vacuum system was modified with an inductively coupled plasma (ICP) coil enabling ion assisted physical vapor deposition of CuIn1-xGaxSe2 thin films on GaAs single crystals and stainless steel foils. With <80 W rf power to the ICP coil at 620-740 °C, film morphologies were unchanged compared to those grown without the ICP. At low temperature (600-670 °C) and high rf power (80-400 W), a light absorbing nanostructured highly anisotropic platelet morphology was produced with surface planes dominated by {112}T facets. At 80-400 W rf power and 640-740 °C, both interconnected void and small platelet morphologies were observed while at >270 W and above >715 °C nanostructured pillars with large inter-pillar voids were produced. The latter appeared black and exhibited a strong {112}T texture with interpillar twist angles of ±8°. Application of a negative dc bias of 0-50 V to the film during growth was not found to alter the film morphology or stoichiometry. The results are interpreted as resulting from the plasma causing strong etching favoring formation of {112}T planes and preferential nucleation of new grains, balanced against conventional thermal diffusion and normal growth mechanisms at higher temperatures. The absence of effects due to applied substrate bias suggests that physical sputtering or ion bombardment effects were minimal. The nanostructured platelet and pillar films were found to exhibit less than one percent reflectivity at angles up to 75° from the surface normal.

Preparation of pure chitosan film using ternary solvents and its super absorbency.

PubMed

Wang, Xuejun; Lou, Tao; Zhao, Wenhua; Song, Guojun

2016-11-20

Chemical modification and graft copolymerization were commonly adopted to prepare super absorbent materials. However, physical microstructure of pure chitosan film was optimized to improve the water uptake capacity in this study. Chitosan films with micro-nanostructure were prepared by a ternary solvent system. The optimal process parameters are 1% acetic acid water solution: dioxane: dimethyl sulfoxide=90: 2.5: 7.5 (v/v/v) with chitosan concentration at 1.25% (w/v). The water uptake capacity of the chitosan film prepared under the optimal process parameters was 896g/g. The prepared chitosan films also exhibited high water uptake capacity in response to external stimuli such as temperature, pH and salt. This finding may provide another way for improving the water absorbency. The pure chitosan film may find potential applications especially in the fields of hygienic products and biomedicine due to its super water absorbency and nontoxicity. Copyright © 2016 Elsevier Ltd. All rights reserved.

The relationship between absorbency and density of bioplastic film made from hydrolyzed starch

NASA Astrophysics Data System (ADS)

Singan, Grace; Chiang, Liew Kang

2017-12-01

Water absorption in polymer blends such as starch-based bioplastic films is important to evaluate the stability characteristics of such films in water that will affect their long-term performance in final products. In this study, the absorbency of starch-based bioplastic films made from potato, cassava, and corn starches that have went through the hydrolysis process first to alter its characteristics and properties in terms of granular swelling and hydrophilicity behaviour. The final results showed that hydrolyzed cassava bioplastic film has the ability to absorb more water compared to hydrolyzed potato and corn bioplastic films. The reading of hydrolyzed cassava bioplastic film on the seventh day of immersion for all ratios were between 87.83 % to 131.29 %, while for hydrolyzed potato bioplastic films was 69.48 % to 92.41 % and hydrolyzed corn bioplastic films was 66.28 % to 74.18 %. Meanwhile, the density analysis was evaluated to determine its physical properties towards moisture condition. The results showed that the hydrolyzed cassava bioplastic films have higher density compared to the other two, which indicated that it is a more favourable raw material to produce biodegradable planting pot due to its ability to absorb more water. Hence, still manage to retain its shape with low brittle surface.

Enhancement of conduction noise absorption by hybrid absorbers composed of indium-tin-oxide thin film and magnetic composite sheet on a microstrip line

NASA Astrophysics Data System (ADS)

Kim, Sun-Hong; Kim, Sung-Soo

2014-05-01

In order to develop wide-band noise absorbers with a focused design for low frequency performance, this study investigates hybrid absorbers that are composed of conductive indium-tin-oxide (ITO) thin film and magnetic composite sheets. The ITO films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ω m. Rubber composites with flaky Fe-Si-Al particles are used as the magnetic sheet with a high permeability and high permittivity. For the ITO film with a low surface resistance and covered by the magnetic sheet, approximately 90% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or ITO film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the ITO film through increased electric field strength bounded by the upper magnetic composite sheet. However, for the reverse layering sequence of the ITO film, the electric field experienced by ITO film is very weak due to the electromagnetic shielding by the under layer of magnetic sheet, which does not result in enhanced power absorption.

EUVL Mask Blank Repair

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barty, A; Mirkarimi, P; Stearns, D G

2002-05-22

EUV mask blanks are fabricated by depositing a reflective Mo/Si multilayer film onto super-polished substrates. Small defects in this thin film coating can significantly alter the reflected field and introduce defects in the printed image. Ideally one would want to produce defect-free mask blanks; however, this may be very difficult to achieve in practice. One practical way to increase the yield of mask blanks is to effectively repair multilayer defects, and to this effect they present two complementary defect repair strategies for use on multilayer-coated EUVL mask blanks. A defect is any area on the mask which causes unwanted variationsmore » in EUV dose in the aerial image obtained in a printing tool, and defect repair is correspondingly defined as any strategy that renders a defect unprintable during exposure. The term defect mitigation can be adopted to describe any strategy which renders a critical defect non-critical when printed, and in this regard a non-critical defect is one that does not adversely affect device function. Defects in the patterned absorber layer consist of regions where metal, typically chrome, is unintentionally added or removed from the pattern leading to errors in the reflected field. There currently exists a mature technology based on ion beam milling and ion beam assisted deposition for repairing defects in the absorber layer of transmission lithography masks, and it is reasonable to expect that this technology will be extended to the repair of absorber defects in EUVL masks. However, techniques designed for the repair of absorber layers can not be directly applied to the repair of defects in the mask blank, and in particular the multilayer film. In this paper they present for the first time a new technique for the repair of amplitude defects as well as recent results on the repair of phase defects.« less

Aqueous Solution-Deposited Molybdenum Oxide Films as an Anode Interfacial Layer for Organic Solar Cells.

PubMed

Yi, Qinghua; Zhai, Pengfei; Sun, Yinghui; Lou, Yanhui; Zhao, Jie; Sun, Baoquan; Patterson, Brian; Luo, Hongmei; Zhang, Wenrui; Jiao, Liang; Wang, Haiyan; Zou, Guifu

2015-08-26

In this study, we report the growth of molybdenum oxide (MoOx) film by polymer-assisted deposition (PAD), an environmentally friendly strategy in an aqueous system. The MoOx film has good crystal quality and is dense and smooth. The transparency of the film is >95% in the wavelength range of 300-900 nm. The device based on P3HT:PCBM absorber material was fabricated. The solar cell with PAD-MoOx as an anode interfacial layer exhibits great performance, even better than that of a solar cell with PSS or evaporated MoOx as an anode interfacial layer. More importantly, the solar cells based on the growth of MoOx have a longer term stability than that of solar cells based on PSS. These results demonstrate the aqueous PAD technology provides an alternative strategy not only for the thin films' growth of applied materials but also for the solution processing for the low-cost fabrication of future materials to be applied in the field of solar cells.

Aging behavior of near atmospheric N2 ambient sputtered/patterned Au IR absorber thin films

NASA Astrophysics Data System (ADS)

Gaur, Surender P.; Kothari, Prateek; Rangra, Kamaljit; Kumar, Dinesh

2018-03-01

Near atmospheric N2 ambient sputtered Au thin films exhibit significant spectral absorptivity over medium to long wave infrared radiations. Thin films were found adequately robust for micropatterning using conventional photolithography and metal lift off processes. Since long term spectral absorptivity is major practical concern for Au blacks, this paper reports on aging behavior of near atmospheric Ar and Ar + N2 (1:1) ambient sputtered infrared absorber Au thin films. Comparative analysis on electrical, morphological and spectral absorption behavior of twenty-five weeks room temperature/vacuum aged Au infrared absorber thin films is performed. The Ar and Ar + N2 ambient sputtered Au thing films have shown anticipated consistency in their physical, electrical and spectral properties regardless the long term aging in this work.

An improved method for determination of refractive index of absorbing films: A simulation study

NASA Astrophysics Data System (ADS)

Özcan, Seçkin; Coşkun, Emre; Kocahan, Özlem; Özder, Serhat

2017-02-01

In this work an improved version of the method presented by Gandhi was presented for determination of refractive index of absorbing films. In this method local maxima of consecutive interference order in transmittance spectrum are used. The method is based on the minimizing procedure leading to the determination of interference order accurately by using reasonable Cauchy parameters. It was tested on theoretically generated transmittance spectrum of absorbing film and the details of the minimization procedure were discussed.

Hybrid absorbers composed of Fe3O4 thin film and magnetic composite sheet and enhancement of conduction noise absorption on a microstrip line

NASA Astrophysics Data System (ADS)

Kim, Sung-Soo

2015-05-01

In response to develop wide-band noise absorbers with an improved low-frequency performance, this study investigates hybrid absorbers that are composed of conductive Fe3O4 thin film and magnetic composite sheets. The Fe3O4 films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ωm. Rubber composites with flaky Fe-Si-Al particles of a high permeability and high permittivity are used as the magnetic sheet functioning as an electromagnetic shield barrier. Microstrip lines with a characteristic impedance of 50 Ω are used to measure the noise absorbing properties. For the Fe3O4 film with a low surface resistance and covered by the magnetic sheet, approximately 80% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or Fe3O4 film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the Fe3O4 film through increased electric field strength bounded by the upper magnetic composite sheet. The noise absorption is further enhanced through increasing the electrical conductivity of the film containing more conductive phase (Fe3O4 + Fe), which can be prepared in a reduced oxygen partial pressure during reactive sputtering.

IR Reflectance Properties Of Weakly And Strongly Absorbing Surface Films

NASA Astrophysics Data System (ADS)

Yen, Yu-Sze; Wong, James S.

1989-12-01

In an external reflection measurement, the optical properties of a surface film can give rise to a variety of spectral behavior on metallic and nonmetallic substrates. The diversity of behavior can be explained by the presence of transverse optical (TO) and longitudinal optical (LO) bands of the film in the infrared region. The excitation modes associated with these bands are directional with respect to the plane of the surface. Spectral interpretation is facilitated by understanding the roles of the TO and LO bands in reflectance spectra, the substrate selection rules for the appearance of these bands, and the relationship between the TO and LO frequencies. We will show that weakly absorbing films have a simpler optical behavior than strongly absorbing films.

High-throughput measurement of polymer film thickness using optical dyes

NASA Astrophysics Data System (ADS)

Grunlan, Jaime C.; Mehrabi, Ali R.; Ly, Tien

2005-01-01

Optical dyes were added to polymer solutions in an effort to create a technique for high-throughput screening of dry polymer film thickness. Arrays of polystyrene films, cast from a toluene solution, containing methyl red or solvent green were used to demonstrate the feasibility of this technique. Measurements of the peak visible absorbance of each film were converted to thickness using the Beer-Lambert relationship. These absorbance-based thickness calculations agreed within 10% of thickness measured using a micrometer for polystyrene films that were 10-50 µm. At these thicknesses it is believed that the absorbance values are actually more accurate. At least for this solvent-based system, thickness was shown to be accurately measured in a high-throughput manner that could potentially be applied to other equivalent systems. Similar water-based films made with poly(sodium 4-styrenesulfonate) dyed with malachite green oxalate or congo red did not show the same level of agreement with the micrometer measurements. Extensive phase separation between polymer and dye resulted in inflated absorbance values and calculated thickness that was often more than 25% greater than that measured with the micrometer. Only at thicknesses below 15 µm could reasonable accuracy be achieved for the water-based films.

Thin films with disordered nanohole patterns for solar radiation absorbers

NASA Astrophysics Data System (ADS)

Fang, Xing; Lou, Minhan; Bao, Hua; Zhao, C. Y.

2015-06-01

The radiation absorption in thin films with three disordered nanohole patterns, i.e., random position, non-uniform radius, and amorphous pattern, are numerically investigated by finite-difference time-domain (FDTD) simulations. Disorder can alter the absorption spectra and has an impact on the broadband absorption performance. Compared to random position and non-uniform radius nanoholes, amorphous pattern can induce a much better integrated absorption. The power density spectra indicate that amorphous pattern nanoholes reduce the symmetry and provide more resonance modes that are desired for the broadband absorption. The application condition for amorphous pattern nanoholes shows that they are much more appropriate in absorption enhancement for weak absorption materials. Amorphous silicon thin films with disordered nanohole patterns are applied in solar radiation absorbers. Four configurations of thin films with different nanohole patterns show that interference between layers in absorbers will change the absorption performance. Therefore, it is necessary to optimize the whole radiation absorbers although single thin film with amorphous pattern nanohole has reached optimal absorption.

Solar collector

DOEpatents

Wilhelm, William G.

1982-01-01

The field of this invention is solar collectors, and more particularly, the invention pertains to a flat plate collector that employs high performance thin films. The solar collector of this invention overcomes several problems in this field, such as excessive hardware, cost and reliability, and other prior art drawbacks outlined in the specification. In the preferred form, the apparatus features a substantially rigid planar frame (14). A thin film window (42) is bonded to one planar side of the frame. An absorber (24) of laminate construction is comprised of two thin film layers (24a, 24b) that are sealed perimetrically. The layers (24a, 24b) define a fluid-tight planar envelope (24c) of large surface area to volume through which a heat transfer fluid flows. Absorber (24) is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

Method of improving field emission characteristics of diamond thin films

DOEpatents

Krauss, A.R.; Gruen, D.M.

1999-05-11

A method of preparing diamond thin films with improved field emission properties is disclosed. The method includes preparing a diamond thin film on a substrate, such as Mo, W, Si and Ni. An atmosphere of hydrogen (molecular or atomic) can be provided above the already deposited film to form absorbed hydrogen to reduce the work function and enhance field emission properties of the diamond film. In addition, hydrogen can be absorbed on intergranular surfaces to enhance electrical conductivity of the diamond film. The treated diamond film can be part of a microtip array in a flat panel display. 3 figs.

Method of improving field emission characteristics of diamond thin films

DOEpatents

Krauss, Alan R.; Gruen, Dieter M.

1999-01-01

A method of preparing diamond thin films with improved field emission properties. The method includes preparing a diamond thin film on a substrate, such as Mo, W, Si and Ni. An atmosphere of hydrogen (molecular or atomic) can be provided above the already deposited film to form absorbed hydrogen to reduce the work function and enhance field emission properties of the diamond film. In addition, hydrogen can be absorbed on intergranular surfaces to enhance electrical conductivity of the diamond film. The treated diamond film can be part of a microtip array in a flat panel display.

Omnidirectional, broadband light absorption using large-area, ultrathin lossy metallic film coatings

NASA Astrophysics Data System (ADS)

Li, Zhongyang; Palacios, Edgar; Butun, Serkan; Kocer, Hasan; Aydin, Koray

2015-10-01

Resonant absorbers based on nanostructured materials are promising for variety of applications including optical filters, thermophotovoltaics, thermal emitters, and hot-electron collection. One of the significant challenges for such micro/nanoscale featured medium or surface, however, is costly lithographic processes for structural patterning which restricted from industrial production of complex designs. Here, we demonstrate lithography-free, broadband, polarization-independent optical absorbers based on a three-layer ultrathin film composed of subwavelength chromium (Cr) and oxide film coatings. We have measured almost perfect absorption as high as 99.5% across the entire visible regime and beyond (400-800 nm). In addition to near-ideal absorption, our absorbers exhibit omnidirectional independence for incidence angle over ±60 degrees. Broadband absorbers introduced in this study perform better than nanostructured plasmonic absorber counterparts in terms of bandwidth, polarization and angle independence. Improvements of such “blackbody” samples based on uniform thin-film coatings is attributed to extremely low quality factor of asymmetric highly-lossy Fabry-Perot cavities. Such broadband absorber designs are ultrathin compared to carbon nanotube based black materials, and does not require lithographic processes. This demonstration redirects the broadband super absorber design to extreme simplicity, higher performance and cost effective manufacturing convenience for practical industrial production.

Effect of reactive monomer on PS-b-P2VP film with UV irradiation

NASA Astrophysics Data System (ADS)

Kim, H. J.; Shin, D. M.

2012-03-01

Poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP) lamellar film which is hydrophobic block hydrophilic polyelectrolyte block polymer of 52 kg/mol -b- 57 kg/mol and PS-b-P2VP film with reactive monomer (RM257) were prepared for photonic gel films. The lamellar stacks, which is alternating layer of hydrophilic and hydrophobic part of PS-b-P2VP. We reported about the influence of reactive monomer on those photonic gel films. Added reactive monomer photonic gel film had higher absorbance than pure photonic gel films. And band gaps of the lamellar films shifted by the time of UV light irradiation. That Photonic gel films were measured with the UV spectrophotometer. As a result the photonic gel film with reactive monomer had more clear color. The lamellar films were swollen by DI water, Ethyl alcohol (aq) and calcium carbonate solution. Since the domain spacing of dried photonic gel films were not showing any color in visible wavelength. The band gap of the lamellar films were drastically shifted to longer wavelength swollen by calcium carbonate solution (absorbance peak 565nm-->617nm). And the lamellar films were shifted to shorter wave length swollen by ethanol (absorbance peak 565nm-->497nm). So each Photonic gel film showed different color.

Electrical and optical percolations in PMMA/GNP composite films

NASA Astrophysics Data System (ADS)

Arda, Ertan; Mergen, Ömer Bahadır; Pekcan, Önder

2018-05-01

Effects of graphene nanoplatelet (GNP) addition on the electrical conductivity and optical absorbance of poly(methyl methacrylate)/graphene nanoplatelet (PMMA/GNP) composite films were studied. Optical absorbance and two point probe resistivity techniques were used to determine the variations of the optical and electrical properties of the composites, respectively. Absorbance intensity, A, and surface resistivity, Rs, of the composite films were monitored as a function of GNP mass fraction (M) at room temperature. Absorbance intensity values of the composites were increased and surface resistivity values were decreased by increasing the content of GNP in the composite. Electrical and optical percolation thresholds of composite films were determined as Mσ = 27.5 wt.% and Mop = 26.6 wt.%, respectively. The conductivity and the optical results were attributed to the classical and site percolation theories, respectively. Optical (βop) and electrical (βσ) critical exponents were calculated as 0.40 and 1.71, respectively.

Implanted Silicon Resistor Layers for Efficient Terahertz Absorption

NASA Technical Reports Server (NTRS)

Chervenak, J. A.; Abrahams, J.; Allen, C. A.; Benford, D. J.; Henry, R.; Stevenson, T.; Wollack, E.; Moseley, S. H.

2005-01-01

Broadband absorption structures are an essential component of large format bolometer arrays for imaging GHz and THz radiation. We have measured electrical and optical properties of implanted silicon resistor layers designed to be suitable for these absorbers. Implanted resistors offer a low-film-stress, buried absorber that is robust to longterm aging, temperature, and subsequent metals processing. Such an absorber layer is readily integrated with superconducting integrated circuits and standard micromachining as demonstrated by the SCUBA II array built by ROE/NIST (1). We present a complete characterization of these layers, demonstrating frequency regimes in which different recipes will be suitable for absorbers. Single layer thin film coatings have been demonstrated as effective absorbers at certain wavelengths including semimetal (2,3), thin metal (4), and patterned metal films (5,6). Astronomical instrument examples include the SHARC II instrument is imaging the submillimeter band using passivated Bi semimetal films and the HAWC instrument for SOFIA, which employs ultrathin metal films to span 1-3 THz. Patterned metal films on spiderweb bolometers have also been proposed for broadband detection. In each case, the absorber structure matches the impedance of free space for optimal absorption in the detector configuration (typically 157 Ohms per square for high absorption with a single or 377 Ohms per square in a resonant cavity or quarter wave backshort). Resonant structures with -20% bandwidth coupled to bolometers are also under development; stacks of such structures may take advantage of instruments imaging over a wide band. Each technique may enable effective absorbers in imagers. However, thin films tend to age, degrade or change during further processing, can be difficult to reproduce, and often exhibit an intrinsic granularity that creates complicated frequency dependence at THz frequencies. Thick metal films are more robust but the requirement for patterning can limit their absorption at THz frequencies and their heat capacity can be high. patterned absorber structures that offer low heat capacity, absence of aging, and uniform, predictable behavior at THz frequencies. We have correlated DC electrical and THz optical measurements of a series of implanted layers and studied their frequency dependence of optical absorption from .3 to 10 THz at cryogenic temperatures. We have modeled the optical response to determine the suitability of the implanted silicon resistor as a function of resistance in the range 10 Ohms/sq to 300 Ohms/sq.

Thin-film optical initiator

DOEpatents

Erickson, Kenneth L.

2001-01-01

A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film. The resultant thin-film optical initiator system also comprises a fiber-optic cable connected to a low-energy laser source, an output charge, and an initiator housing. The reactive thin film, which may contain very thin embedded layers or be a co-deposit of a light-absorbing material such as carbon, absorbs the incident laser light, is volumetrically heated, and explodes against the output charge, imparting about 5 to 20 times more energy than in the incident laser pulse.

Thin Semiconductor/Metal Films For Infrared Devices

NASA Technical Reports Server (NTRS)

Lamb, James L.; Nagendra, Channamallappa L.

1995-01-01

Spectral responses of absorbers and reflectors tailored. Thin cermet films composites of metals and semiconductors undergoing development for use as broadband infrared reflectors and absorbers. Development extends concepts of semiconductor and dielectric films used as interference filters for infrared light and visible light. Composite films offer advantages over semiconductor films. Addition of metal particles contributes additional thermal conductivity, reducing thermal gradients and associated thermal stresses, with resultant enhancements of thermal stability. Because values of n in composite films made large, same optical effects achieved with lesser thicknesses. By decreasing thicknesses of films, one not only decreases weights but also contributes further to reductions of thermal stresses.

Optimization of Multilayer Laminated Film and Absorbent of Vacuum Insulation Panel for Use at High Temperature

NASA Astrophysics Data System (ADS)

Araki, Kuninari; Echigoya, Wataru; Tsuruga, Toshimitsu; Kamoto, Daigorou; Matsuoka, Shin-Ichi

For the energy saving regulation and larger capacity, Vacuum Insulation Panel (VIP) has been used in refrigerators with urethane foam in recent years. VIP for low temperature is constructed by laminated plastic film, using heat welding of each neighboring part for keeping vacuum, so that the performance decrement is very large under high temperature. But recently high efficiency insulation material is desired for high temperature water holding devices (automatic vending machine, heat pump water heater, electric hot-water pot water, etc.), and we especially focused on cost and ability of the laminated plastic film and absorbent for high temperature VIP. We measured the heatproof temperature of plastic films and checked the amount of water vapor and out coming gas on temperature-programmed adsorption in absorbent. These results suggest the suitable laminated film and absorbent system for VIP use at high temperature, and the long-term reliability was evaluated by measuring thermal conductivity of high temperature. As a result it was found that high-retort pouch of CPP (cast polypropylene film) and adding of aluminum coating are the most suitable materials for use in the welded layers of high-temperature VIPs (105°C).

Ambient CdCl{sub 2} treatment on CdS buffer layer for improved performance of Sb{sub 2}Se{sub 3} thin film photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Liang; Luo, Miao; Qin, Sikai

2015-10-05

Antimony selenide (Sb{sub 2}Se{sub 3}) is appealing as a promising light absorber because of its intrinsically benign grain boundaries, suitable band gap (∼1.1 eV), strong absorption coefficient, and relatively environmentally friendly constituents. Recently, we achieved a certified 5.6% efficiency Sb{sub 2}Se{sub 3} thin film solar cell with the assistance of ambient CdCl{sub 2} treatment on the CdS buffer layer. Here, we focused on investigating the underlying mechanism from a combined materials and device physics perspective applying current density-voltage (J-V) fitting analysis, atomic force microscope, X-ray photoelectron spectroscopy, fluorescence, and UV–Vis transmission spectroscopy. Our results indicated that ambient CdCl{sub 2} treatment onmore » CdS film not only improved CdS grain size and quality, but also incorporated Cl and more O into the film, both of which can significantly improve the heterojunction quality and device performance of CdS/Sb{sub 2}Se{sub 3} solar cells.« less

Transparent sunlight conversion film based on carboxymethyl cellulose and carbon dots.

PubMed

You, Yaqin; Zhang, Haoran; Liu, Yingliang; Lei, Bingfu

2016-10-20

Transparent sunlight conversion film based on carboxymethyl cellulose (CMC) and carbon dots (CDs) has been developed for the first time through dispersion of CDs in CMC aqueous solution. Due to the hydrogen bonds interaction, CMC can effectively absorb the CDs, whose surfaces are functionalized by lots of polar groups. The results from atomic force microscopy (AFM), scanning electron microscopy (SEM) confirm that the composite film possesses a homogeneous and compact structure. Besides, the CMC matrix neither competes for absorbing excitation light nor absorbs the emissions of CDs, which reserves the inherent optical properties of the individual CDs. The composite films can efficiently convert ultraviolet light to blue light. What's more, the film is transparent and possesses excellent mechanical properties, expected to apply in the field of agricultural planting for sunlight conversion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Design of a wide-band metamaterial absorber based on fractal frequency selective surface and resistive films

NASA Astrophysics Data System (ADS)

Cheng, Yong-Zhi; Nie, Yan; Gong, Rong-Zhou

2013-10-01

We present the design of a wide-band metamaterial absorber, based on fractal frequency selective surface and resistive films. The total thickness is only 0.8 mm and shows a polarization-insensitive and wide-angle strong absorption. Due to the multiband resonance properties of the Minkowski fractal loop structure and Ohmic loss properties of resistive films, a strongly absorptive bandwidth of about 19 GHz is demonstrated numerically in the range 6.51-25.42 GHz. This design provides an effective and feasible way to construct a broad-band absorber in stealth technology.

A facile fabrication of chemically converted graphene oxide thin films and their uses as absorber materials for solar cells

NASA Astrophysics Data System (ADS)

Adelifard, Mehdi; Darudi, Hosein

2016-07-01

There is a great interest in the use of graphene sheets in thin film solar cells with low-cost and good-optoelectronic properties. Here, the production of absorbent conductive reduced graphene oxide (RGO) thin films was investigated. RGO thin films were prepared from spray-coated graphene oxide (GO) layers at various substrate temperature followed by a simple hydrazine-reducing method. The structural, morphological, optical, and electrical characterizations of graphene oxide (GO) and RGO thin films were investigated. X-ray diffraction analysis showed a phase shift from GO to RGO due to hydrazine treatment, in agreement with the FTIR spectra of the layers. FESEM images clearly exhibited continuous films resulting from the overlap of graphene nanosheets. The produced low-cost thin films had high absorption coefficient up to 1.0 × 105 cm-1, electrical resistance as low as 0.9 kΩ/sq, and effective optical band gap of about 1.50 eV, close to the optimum value for solar conversion. The conductive absorbent properties of the reduced graphene oxide thin films would be useful to develop photovoltaic cells.

Spectroscopic investigation of the chemical and electronic properties of chalcogenide materials for thin-film optoelectronic devices

NASA Astrophysics Data System (ADS)

Horsley, Kimberly Anne

Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials. For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe 2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These techniques enabled the investigation of the chemical and electronic structure of the materials, both at the surface and towards the bulk. CdS/Cu(In,Ga)Se2 thin-films produced from the roll-to-roll, ambient pressure, Nanosolar industrial line were studied. While record-breaking efficiency cells are usually prepared in high-vacuum (HV) or ultra-high vacuum (UHV) environments, these samples demonstrate competitive mass-production efficiency without the high-cost deposition environment. We found relatively low levels of C contaminants, limited Na and Se oxidation, and a S-Se intermixing at the CdS/CIGSe interface. The surface band gap compared closely to previously investigated CIGSe thin-films deposited under vacuum, illustrating that roll-to-roll processing is a promising and less-expensive alternative for solar cell production. An alternative deposition process for CuInSe2 was also studied, in collaboration with the University of Luxembourg. CuInSe2 absorbers were prepared with varying Cu content and surface treatments to investigate the potential to produce an absorber with a Cu-rich bulk and Cu-poor surface. This is desired to combine the bulk characteristics of reduced defects and larger grains in Cu-rich films, while maintaining a wide surface band gap, as seen in Cu-poor films. A novel absorber was prepared Cu-rich with a final In-Se treatment to produce a Cu-poor surface, and compared directly to Cu-poor and Cu-rich produced samples. Despite reduced Cu at the surface, the novel absorber was found to have a surface band gap similar to that of traditional, Cu-poor grown absorbers. Furthermore, estimation of the near-surface bulk band gap suggests a narrowing of the band gap away from the surface, similar to highly efficient, Cu-poor grown absorbers. Long-term degradation is another concern facing solar cells, as heat and moistures stress can result in reduced efficiencies over time. The interface of the back contact material and absorber layer in (Au/Cu)/CdTe/CdS thin-film structures from the University of Toledo were investigated after a variety of accelerated stress treatments with the aim of further understanding the chemical and/or electronic degradation of this interface. Sulfur migration to the back contact was observed, along with the formation of Au-S and Cu-S bonds. A correlation between heat stress under illumination and the formation of Cu-Cl bonds was also found. Nanocomposite materials hold promise as a next-generation photovoltaic material and for use in LED devices, due in part to the unique ability to tune the absorption edge of the film by adjusting the semiconductor particle size, and the prospective for long-range charge-carrier (exciton) transport through the wide band gap matrix material. Thin films of CdTe were sputter deposited onto ZnO substrates at the University of Arizona and studied before and after a short, high temperature annealing to further understand the effects of annealing on the CdTe/ZnO interface. A clumping of the CdTe layer and the formation of Cd- and Te-oxides was observed using surface microscopy and photoelectron spectroscopy techniques. These findings help to evaluate post-deposition annealing as a treatment to adjust the final crystallinity and optoelectronic properties of these films. Through publication and/or discussion with collaborators, each project presented in this dissertation contributed to the understanding of the chemical and electronic properties of the material surface, near-surface bulk, and/or interfaces formed. The information gained on these unique chalcogenide materials will assist in designing more efficient and successful optoelectronic devices for the next generation of solar cells and LEDs.

Modification of UV absorption profile of polymer film reflectors to increase solar-weighted reflectance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorgensen, Gary; Gee, Randall C.; White, David

Provided are reflective thin film constructions including a reduced number of layers, which provides for increased solar-weighted hemispherical reflectance and durability. Reflective films include those comprising an ultraviolet absorbing abrasion resistant coating over a metal layer. Also provided are ultraviolet absorbing abrasion resistant coatings and methods for optimizing the ultraviolet absorption of an abrasion resistant coating. Reflective films disclosed herein are useful for solar reflecting, solar collecting, and solar concentrating applications, such as for the generation of electrical power.

Synthesis of Cu2ZnSnS4 thin films by a precursor solution paste for thin film solar cell applications.

PubMed

Cho, Jin Woo; Ismail, Agus; Park, Se Jin; Kim, Woong; Yoon, Sungho; Min, Byoung Koun

2013-05-22

Cu2ZnSnS4 (CZTS) is a very promising semiconductor material when used for the absorber layer of thin film solar cells because it consists of only abundant and inexpensive elements. In addition, a low-cost solution process is applicable to the preparation of CZTS absorber films, which reduces the cost when this film is used for the production of thin film solar cells. To fabricate solution-processed CZTS thin film using an easily scalable and relatively safe method, we suggest a precursor solution paste coating method with a two-step heating process (oxidation and sulfurization). The synthesized CZTS film was observed to be composed of grains of a size of ~300 nm, showing an overall densely packed morphology with some pores and voids. A solar cell device with this film as an absorber layer showed the highest efficiency of 3.02% with an open circuit voltage of 556 mV, a short current density of 13.5 mA/cm(2), and a fill factor of 40.3%. We also noted the existence of Cd moieties and an inhomogeneous Zn distribution in the CZTS film, which may have been triggered by the presence of pores and voids in the CZTS film.

Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

NASA Technical Reports Server (NTRS)

Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

1989-01-01

The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

Characterization of Thymol blue Radiochromic dosimeters for high dose applications

NASA Astrophysics Data System (ADS)

Aldweri, Feras M.; Abuzayed, Manar H.; Al-Ajaleen, Musab S.; Rabaeh, Khalid A.

2018-03-01

Thymol blue (TB) solutions and Thymol blue Polyvinyl Alcohol (TB-PVA) films have been introduced as Radiochromic dosimeter for high dose applications. The dosimeters were irradiated with gamma ray (60Co source) from 5 to 30 kGy for film, and from 0.150 kGy to 4 kGy for solution. The optical density of unirradiated and irradiated TB solution as well as TB-PVA film dosimeters were studied in terms of absorbance at 434 nm using UV/VIS spectrophotometer. The effects of scan temperature, light pre-gamma irradiation, dose rate, relative humidity and stability of the absorbance of solutions and films after irradiation were investigated. We found the dose sensitivity of TB solution and TB-PVA film dosimeters increases significantly with increases of the absorbed dose as well as with the increases of TB dye concentrations. The useful dose range of developed TB solutions and TB-PVA films dosimeters is in the range 0.125-1 kGy and of 5-20 kGy, respectively.

Electrochemically exfoliated graphene as a novel microwave susceptor: the ultrafast microwave-assisted synthesis of carbon-coated silicon-graphene film as a lithium-ion battery anode.

PubMed

Kim, Jong Min; Ko, Dongjin; Oh, Jiseop; Lee, Jeongyeon; Hwang, Taejin; Jeon, Youngmoo; Hooch Antink, Wytse; Piao, Yuanzhe

2017-10-19

Graphene nanocomposites have attracted much attention in many applications due to their superior properties. However, preparing graphene nanocomposites requires a time-consuming thermal treatment to reduce the graphene or synthesize nanomaterials, in most cases. We present an ultrafast synthesis of a carbon-coated silicon-graphene nanocomposite using a commercial microwave system. Electrochemically exfoliated graphene is used as a novel microwave susceptor to deliver efficient microwave energy conversion. Unlike graphene oxide, it does not require a time-consuming pre-thermal reduction or toxic chemical reduction to absorb microwave radiation efficiently. A carbon-coated silicon nanoparticle-electrochemically exfoliated graphene nanocomposite film was prepared by a few seconds' microwave irradiation. The sp 2 domains of graphene absorb microwave radiation and generate heat to simultaneously reduce the graphene and carbonize the polydopamine carbon precursor. The as-prepared N-doped carbon-coated silicon-graphene film was used as a lithium-ion battery anode. The N-doped carbon coating decreases the contact resistance between silicon nanoparticles and graphene provides a wide range conductive network. Consequently, it exhibited a reversible capacity of 1744 mA h g -1 at a current density of 0.1 A g -1 and 662 mA h g -1 at 1.0 A g -1 after 200 cycles. This method can potentially be a general approach to prepare various graphene nanocomposites in an extremely short time.

Effect of composition on SILAR deposited CdxZn1-xS thin films

NASA Astrophysics Data System (ADS)

Ashith V., K.; Gowrish Rao, K.

2018-04-01

In the group of II-VI compound semiconductor, cadmium zinc sulphide (CdxZn1-xS) thin films have broad application in photovoltaic, optoelectronic devices etc. For heterojunction aspects, CdxZn1-xS thin film can be used as heterojunction partner for CdTe as the absorber layer. In this work, CdZnS thin films prepared on glass substrates by Successive Ion Layer Adsorption and Reaction (SILAR) method by varying the composition. The XRD patterns of deposited films showed polycrystalline with the hexagonal phase. The crystallite size of the films was estimated from W-H plot. The bond length of the film varied w.r.to the composition of the CdxZn1-xS films. The urbach energy of the films was calcualted from absorbance data.

Low-loss flake-graphene saturable absorber mirror for laser mode-locking at sub-200-fs pulse duration

NASA Astrophysics Data System (ADS)

Cunning, B. V.; Brown, C. L.; Kielpinski, D.

2011-12-01

Saturable absorbers are a key component for mode-locking femtosecond lasers. Polymer films containing graphene flakes have recently been used in transmission as laser mode-lockers but suffer from high nonsaturable loss, limiting their application in low-gain lasers. Here, we present a saturable absorber mirror based on a film of pure graphene flakes. The device is used to mode lock an erbium-doped fiber laser, generating pulses with state-of-the-art, sub-200-fs duration. The laser characteristic indicates that the film exhibits low nonsaturable loss (13% per pass) and large absorption modulation depth (45% of low-power absorption).

Absorbing TiOx thin film enabling laser welding of polyurethane membranes and polyamide fibers

PubMed Central

Amberg, Martin; Haag, Alexander; Storchenegger, Raphael; Rupper, Patrick; Lehmeier, Frederike; Rossi, René M; Hegemann, Dirk

2015-01-01

We report on the optical properties of thin titanium suboxide (TiOx) films for applications in laser transmission welding of polymers. Non-absorbing fibers were coated with TiOx coatings by reactive magnetron sputtering. Plasma process parameters influencing the chemical composition and morphology of the deposited thin films were investigated in order to optimize their absorption properties. Optical absorption spectroscopy showed that the oxygen content of the TiOx coatings is the main parameter influencing the optical absorbance. Overtreatment (high power plasma input) of the fiber surface leads to high surface roughness and loss of mechanical stability of the fiber. The study shows that thin substoichiometric TiOx films enable the welding of very thin polyurethane membranes and polyamide fibers with improved adhesion properties. PMID:27877837

Absorbing TiOx thin film enabling laser welding of polyurethane membranes and polyamide fibers

NASA Astrophysics Data System (ADS)

Amberg, Martin; Haag, Alexander; Storchenegger, Raphael; Rupper, Patrick; Lehmeier, Frederike; Rossi, René M.; Hegemann, Dirk

2015-10-01

We report on the optical properties of thin titanium suboxide (TiOx) films for applications in laser transmission welding of polymers. Non-absorbing fibers were coated with TiOx coatings by reactive magnetron sputtering. Plasma process parameters influencing the chemical composition and morphology of the deposited thin films were investigated in order to optimize their absorption properties. Optical absorption spectroscopy showed that the oxygen content of the TiOx coatings is the main parameter influencing the optical absorbance. Overtreatment (high power plasma input) of the fiber surface leads to high surface roughness and loss of mechanical stability of the fiber. The study shows that thin substoichiometric TiOx films enable the welding of very thin polyurethane membranes and polyamide fibers with improved adhesion properties.

Absorbing TiO x thin film enabling laser welding of polyurethane membranes and polyamide fibers.

PubMed

Amberg, Martin; Haag, Alexander; Storchenegger, Raphael; Rupper, Patrick; Lehmeier, Frederike; Rossi, René M; Hegemann, Dirk

2015-10-01

We report on the optical properties of thin titanium suboxide (TiO x ) films for applications in laser transmission welding of polymers. Non-absorbing fibers were coated with TiO x coatings by reactive magnetron sputtering. Plasma process parameters influencing the chemical composition and morphology of the deposited thin films were investigated in order to optimize their absorption properties. Optical absorption spectroscopy showed that the oxygen content of the TiO x coatings is the main parameter influencing the optical absorbance. Overtreatment (high power plasma input) of the fiber surface leads to high surface roughness and loss of mechanical stability of the fiber. The study shows that thin substoichiometric TiO x films enable the welding of very thin polyurethane membranes and polyamide fibers with improved adhesion properties.

Optimization of X-ray Absorbers for TES Microcalorimeters

NASA Technical Reports Server (NTRS)

Iyomoto, Naoko; Sadleir, John E.; Figueroa-Feliciano, Enectali; Saab, Tarek; Bandler, Simon; Kilbourne, Caroline; Chervenak, James; Talley, Dorothy; Finkbeiner, Fred; Brekosky, Regis

2004-01-01

We have investigated the thermal, electrical, and structural properties of Bi and BiCu films that are being developed as X-ray absorbers for transition-edge sensor (TES) microcalorimeter arrays for imaging X-ray spectroscopy. Bi could be an ideal material for an X-ray absorber due to its high X-ray stopping power and low heat capacity, but it has a low thermal conductivity, which can result in position dependence of the pulses in the absorber. In order to improve the thermal conductivity, we added Cu layers in between the Bi layers. We measured electrical and thermal conductivities of the films around 0.1 K(sub 1) the operating temperature of the TES calorimeter, to examine the films and to determine the optimal thickness of the Cu layer. From the electrical conductivity measurements, we found that the Cu is more resistive on the Bi than on a Si substrate. Together with an SEM picture of the Bi surface, we concluded that the rough surface of the Bi film makes the Cu layer resistive when the Cu layer is not thick enough t o fill in the roughness. From the thermal conductivity measurements, we determined the thermal diffusion constant to be 2 x l0(exp 3) micrometers squared per microsecond in a film that consists of 2.25 micrometers of Bi and 0.1 micrometers of Cu. We measured the position dependence in the film and found that its thermal diffusion constant is too low to get good energy resolution, because of the resistive Cu layer and/or possibly a very high heat capacity of our Bi films. We show plans to improve the thermal diffusion constant in our BiCu absorbers.

Evaporation of Particle-Stabilized Emulsion Sunscreen Films.

PubMed

Binks, Bernard P; Fletcher, Paul D I; Johnson, Andrew J; Marinopoulos, Ioannis; Crowther, Jonathan M; Thompson, Michael A

2016-08-24

We recently showed (Binks et al., ACS Appl. Mater. Interfaces, 2016, DOI: 10.1021/acsami.6b02696) how evaporation of sunscreen films consisting of solutions of molecular UV filters leads to loss of UV light absorption and derived sun protection factor (SPF). In the present work, we investigate evaporation-induced effects for sunscreen films consisting of particle-stabilized emulsions containing a dissolved UV filter. The emulsions contained either droplets of propylene glycol (PG) in squalane (SQ), droplets of SQ in PG or droplets of decane in PG. In these different emulsion types, the SQ is involatile and shows no evaporation, the PG is volatile and evaporates relatively slowly, whereas the decane is relatively very volatile and evaporates quickly. We have measured the film mass and area, optical micrographs of the film structure, and the UV absorbance spectra during evaporation. For emulsion films containing the involatile SQ, evaporation of the PG causes collapse of the emulsion structure with some loss of specular UV absorbance due to light scattering. However, for these emulsions with droplets much larger than the wavelength of light, the light is scattered only at small forward angles so does not contribute to the diffuse absorbance and the film SPF. The UV filter remains soluble throughout the evaporation and thus the UV absorption by the filter and the SPF remain approximately constant. Both PG-in-SQ and SQ-in-PG films behave similarly and do not show area shrinkage by dewetting. In contrast, the decane-in-PG film shows rapid evaporative loss of the decane, followed by slower loss of the PG resulting in precipitation of the UV filter and film area shrinkage by dewetting which cause the UV absorbance and derived SPF to decrease. Measured UV spectra during evaporation are in reasonable agreement with spectra calculated using models discussed here.

Passive mode locking of a Nd:YAG laser with a thin gelatine-film saturable absorber containing organic-dye J-aggregates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avdeeva, V I; Shapiro, Boris I; Kuch'yanov, Aleksandr S

2003-06-30

Ultrashort pulses of duration {approx}13 ps are first obtained in a passively mode-locked Nd:YAG laser with a negative feedback using a thin gelatine-film saturable absorber containing organic-dye J-aggregates. (control of laser radiation parameters)

Absorbed dose in AgBr in direct film for photon energies ( < 150 keV): relation to optical density. Theoretical calculation and experimental evaluation.

PubMed

Helmrot, E; Alm Carlsson, G

1996-01-01

In the radiological process it is necessary to develop tools so as to explore how X-rays can be used in the most effective way. Evaluation of models to derive measures of image quality and risk-related parameters is one possibility of getting such a tool. Modelling the image receptor, an important part of the imaging chain, is then required. The aim of this work was to find convenient and accurate ways of describing the blackening of direct dental films by X-rays. Since the beginning of the 20th century, the relation between optical density and photon interactions in the silver bromide in X-ray films has been investigated by many authors. The first attempts used simple quantum theories with no consideration of underlying physical interaction processes. The theories were gradually made more realistic by the introduction of dosimetric concepts and cavity theory. A review of cavity theories for calculating the mean absorbed dose in the AgBr grains of the film emulsion is given in this work. The cavity theories of GREENING (15) and SPIERS-CHARLTON (37) were selected for calculating the mean absorbed dose in the AgBr grains relative to the air collision kerma (Kc,air) of the incident photons of Ultra-speed and Ektaspeed (intraoral) films using up-to-date values of interaction coefficients. GREENING'S theory is a multi-grain theory and the results depend on the relative amounts of silver bromide and gelatine in the emulsion layer. In the single grain theory of SPIERS-CHARLTON, the shape and size of the silver bromide grain are important. Calculations of absorbed dose in the silver bromide were compared with measurements of optical densities in Ultra-speed and Ektaspeed films for a broad range (25-145 kV) of X-ray energy. The calculated absorbed dose values were appropriately averaged over the complete photon energy spectrum, which was determined experimentally using a Compton spectrometer. For the whole range of tube potentials used, the measured optical densities of the films were found to be proportional to the mean absorbed dose in the AgBr grains calculated according to GREENING'S theory. They were also found to be proportional to the collision kerma in silver bromide (Kc,AgBr) indicating proportionality between Kc,AgBr and the mean absorbed dose in silver bromide. While GREENING'S theory shows that the quotient of the mean absorbed dose in silver bromide and Kc,AgBr varies with photon energy, this is not apparent when averaged over the broad (diagnostic) X-ray energy spectra used here. Alternatively, proportionality between Kc,AgBr and the mean absorbed dose in silver bromide can be interpreted as resulting from a combination of the SPIERS-CHARLTON theory, valid at low photon energies ( < 30 keV) and GREENING'S theory, which is strictly valid at energies above 50 keV. This study shows that the blackening of non-screen films can be related directly to the energy absorbed in the AgBr grains of the emulsion layer and that, for the purpose of modelling the imaging chain in intraoral radiography, film response can be represented by Kc,AgBr (at the position of the film) independent of photon energy. The importance of taking the complete X-ray energy spectrum into full account in deriving Kc,AgBr is clearly demonstrated, showing that the concept of effective energy must be used with care.

Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

NASA Astrophysics Data System (ADS)

Deb, K.; Bhowmik, K. L.; Bera, A.; Chattopadhyay, K. K.; Saha, B.

2016-05-01

Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

Graphene Oxide Transparent Hybrid Film and Its Ultraviolet Shielding Property.

PubMed

Xie, Siyuan; Zhao, Jianfeng; Zhang, Bowu; Wang, Ziqiang; Ma, Hongjuan; Yu, Chuhong; Yu, Ming; Li, Linfan; Li, Jingye

2015-08-19

Herein, we first reported a facile strategy to prepare functional Poly(vinyl alcohol) (PVA) hybrid film with well ultraviolet (UV) shielding property and visible light transmittance using graphene oxide nanosheets as UV-absorber. The absorbance of ultraviolet light at 300 nm can be up to 97.5%, while the transmittance of visible light at 500 nm keeps 40% plus. This hybrid film can protect protein from UVA light induced photosensitive damage, remarkably.

Trap-assisted tunneling in aluminum-doped ZnO/indium oxynitride nanodot interlayer Ohmic contacts on p-GaN

NASA Astrophysics Data System (ADS)

Ke, Wen-Cheng; Lee, Fang-Wei; Yang, Cheng-Yi; Chen, Wei-Kuo; Huang, Hao-Ping

2015-10-01

This study developed an Ohmic contact formation method for a ZnO:Al (AZO) transparent conductive layer on p-GaN films involving the introduction of an indium oxynitride (InON) nanodot interlayer. An antisurfactant pretreatment was used to grow InON nanodots on p-GaN films in a RF magnetron sputtering system. A low specific contact resistance of 1.12 × 10-4 Ω cm2 was achieved for a sample annealed at 500 °C for 30 s in nitrogen ambient and embedded with an InON nanodot interlayer with a nanodot density of 6.5 × 108 cm-2. By contrast, a sample annealed in oxygen ambient exhibited non-Ohmic behavior. X-ray photoemission spectroscopy results showed that the oxygen vacancy (Vo) in the InON nanodots played a crucial role in carrier transport. The fitting I-V characteristic curves indicated that the hopping mechanism with an activation energy of 31.6 meV and trap site spacing of 1.1 nm dominated the carrier transport in the AZO/InON nanodot/p-GaN sample. Because of the high density of donor-like oxygen vacancy defects at the InON nanodot/p-GaN interface, positive charges from the underlying p-GaN films were absorbed at the interface. This led to positive charge accumulation, creating a narrow depletion layer; therefore, carriers from the AZO layer passed through InON nanodots by hopping transport, and subsequently tunneling through the interface to enter the p-GaN films. Thus, AZO Ohmic contact can be formed on p-GaN films by embedding an InON nanodot interlayer to facilitate trap-assisted tunneling.

Deposition and characterization of spray pyrolysed p-type Cu2SnS3 thin film for potential absorber layer of solar cell

NASA Astrophysics Data System (ADS)

Thiruvenkadam, S.; Sakthi, P.; Prabhakaran, S.; Chakravarty, Sujay; Ganesan, V.; Rajesh, A. Leo

2018-06-01

Thin film of ternary Cu2SnS3 (CTS), a potential absorber layer for solar cells was successfully deposited by chemical spray pyrolysis technique. The GIXRD pattern revealed that the film having tetragonal Cu2SnS3 phase with the preferential orientation along (112), (200), (220) and (312) plane and it is further confirmed using Raman spectroscopy by the existence of Raman peak at 320 cm-1. Atomic Force Microscopy (AFM) was used to estimate the surface roughness of 28.8 nm. The absorption coefficient was found to be greater than the order of 105 cm-1 and bandgap of 1.70 eV. Hall effect measurement indicates the p type nature of the film with a hole concentration of 1.03 × 1016cm-3 and a hall mobility of 404 cm2/V. The properties of CTS thin film confirmed suitable to be a potential absorber layer material for photovoltaic applications.

Investigation of blister formation in sputtered Cu{sub 2}ZnSnS{sub 4} absorbers for thin film solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bras, Patrice, E-mail: patrice.bras@angstrom.uu.se; Sterner, Jan; Platzer-Björkman, Charlotte

2015-11-15

Blister formation in Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films sputtered from a quaternary compound target is investigated. While the thin film structure, composition, and substrate material are not correlated to the blister formation, a strong link between sputtering gas entrapment, in this case argon, and blistering effect is found. It is shown that argon is trapped in the film during sputtering and migrates to locally form blisters during the high temperature annealing. Blister formation in CZTS absorbers is detrimental for thin film solar cell fabrication causing partial peeling of the absorber layer and potential shunt paths in the complete device.more » Reduced sputtering gas entrapment, and blister formation, is seen for higher sputtering pressure, higher substrate temperature, and change of sputtering gas to larger atoms. This is all in accordance with previous publications on blister formation caused by sputtering gas entrapment in other materials.« less

Wavelength-switchable passively mode-locked fiber laser with mechanically exfoliated molybdenum ditelluride on side-polished fiber

NASA Astrophysics Data System (ADS)

Wang, Guomei

2017-11-01

We experimentally investigated the nonlinear saturable absorption characteristics of molybdenum ditelluride (MoTe2) and demonstrated a wavelength-switchable mode-locked erbium-doped fiber laser (EDFL) by using MoTe2 thin film on side-polished fiber (SPF) as saturable absorber. Here, the MoTe2 thin film was efficiently fabricated via mechanical exfoliation method and transferred onto the SPF with the assistance of polydimethylsiloxane (PDMS). MoTe2-covered SPF (MSPF) exhibits the nonlinear saturable absorption for pulses with different polarization states. Optical solitons with spectral bandwidth of 1.06 (1.31) nm centered at ∼1559 (∼1528) nm and pulse duration of 2.46 (2.04) ps can be obtained from the EDFL by adjusting the polarization controller (PC) properly. The time-bandwidth product (TBP) of the pulses was calculated as 0.322 (0.344).

Orientation of Zn3P2 films via phosphidation of Zn precursors

NASA Astrophysics Data System (ADS)

Katsube, Ryoji; Nose, Yoshitaro

2017-02-01

Orientation of solar absorber is an important factor to achieve high efficiency of thin film solar cells. In the case of Zn3P2 which is a promising absorber of low-cost and high-efficiency solar cells, (110)/(001) orientation was only reported in previous studies. We have successfully prepared (101)-oriented Zn3P2 films by phosphidation of (0001)-oriented Zn films at 350 °C. The phosphidation mechanism of Zn is discussed through STEM observations on the partially-reacted sample and the consideration of the relationship between the crystal structures of Zn and Zn3P2 . We revealed that (0001)-oriented Zn led to nucleation of (101)-oriented Zn3P2 due to the similarity in atomic arrangement between Zn and Zn3P2 . The electrical resistivity of the (101)-oriented Zn3P2 film was lower than those of (110)/(001)-oriented films, which is an advantage of the phosphidation technique to the growth processes in previous works. The results in this study demonstrated that well-conductive Zn3P2 films could be obtained by controlling orientations of crystal grains, and provide a guiding principle for microstructure control in absorber materials.

Design and characterization of terahertz-absorbing nano-laminates of dielectric and metal thin films.

PubMed

Bolakis, C; Grbovic, D; Lavrik, N V; Karunasiri, G

2010-07-05

A terahertz-absorbing thin-film stack, containing a dielectric Bragg reflector and a thin chromium metal film, was fabricated on a silicon substrate for applications in bi-material terahertz (THz) sensors. The Bragg reflector is to be used for optical readout of sensor deformation under THz illumination. The THz absorption characteristics of the thin-film composite were measured using Fourier transform infrared spectroscopy. The absorption of the structure was calculated both analytically and by finite element modeling and the two approaches agreed well. Finite element modeling provides a convenient way to extract the amount of power dissipation in each layer and is used to quantify the THz absorption in the multi-layer stack. The calculation and the model were verified by experimentally characterizing the multi-layer stack in the 3-5 THz range. The measured and simulated absorption characteristics show a reasonably good agreement. It was found that the composite film absorbed about 20% of the incident THz power. The model was used to optimize the thickness of the chromium film for achieving high THz absorption and found that about 50% absorption can be achieved when film thickness is around 9 nm.

Microstructures, optical and photovoltaic properties of CH3NH3PbI3(1‑x)Cl x perovskite films with CuSCN additive

NASA Astrophysics Data System (ADS)

Shirahata, Yasuhiro; Oku, Takeo

2018-05-01

Microstructures, optical and photovoltaic properties of CH3NH3PbI3(1‑x)Cl x perovskite films with copper(I) thiocyanate (CuSCN) additive were investigated. The CuSCN-added CH3NH3PbI3(1‑x)Cl x films were prepared by a hot air blow-assisted spin-coating method. Current density–voltage characteristics of the photovoltaic device using the CuSCN-added CH3NH3PbI3(1‑x)Cl x light-absorbing layer showed increases in short-circuit current density, open-circuit voltage, which resulted in increase in the conversion efficiency. Microstructure analysis showed that the crystal structure of the CuSCN-added CH3NH3PbI3(1‑x)Cl x was a pseudocubic system. From these results, partial substitutions of Pb2+ and anions (I‑ and Cl‑) by Cu ions (Cu+ and Cu2+) and SCN‑, respectively, are considered to occur in the CuSCN-added CH3NH3PbI3(1‑x)Cl x films. Based on the obtained results, reaction mechanisms of the CH3NH3PbI3(1‑x)Cl x films with and without CuSCN additive were discussed.

Structural and optical properties of CuS thin films deposited by Thermal co-evaporation

NASA Astrophysics Data System (ADS)

Sahoo, A. K.; Mohanta, P.; Bhattacharyya, A. S.

2015-02-01

Copper sulfide (CuS) thin films with thickness 100, 150 and 200 nm have been deposited on glass substrates by thermal co-evaporation of Copper and Sulphur. The effect of CuS film thickness on the structural and optical properties have investigated and discussed. Structural and optical investigations of the films were carried out by X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy and UV spectroscopy. XRD and selected area electron diffraction conforms that polycrystalline in nature with hexagonal crystal structure. AFM studies revealed a smooth surface morphology with root mean-square roughness values increases from 24 nm to 42 nm as the film thickness increase from 100 nm to 200 nm. AFM image showed that grain size increases with thickness of film increases and good agreement with the calculated from full width half maximum of the X-ray diffraction peak using Scherrer's formula and Williamson-Hall plot. The absorbance of the thin films were absorbed decreases with wavelength through UV-visible regions but showed a increasing in the near-infrared regions. The reflectance spectra also showed lower reflectance peak (25% to 32%) in visible region and high reflectance peak (49 % to 54 %) in near-infrared region. These high absorbance films made them for photo-thermal conversion of solar energy.

Highly efficient Cu(In,Ga)Se2 solar cells grown on flexible polymer films.

PubMed

Chirilă, Adrian; Buecheler, Stephan; Pianezzi, Fabian; Bloesch, Patrick; Gretener, Christina; Uhl, Alexander R; Fella, Carolin; Kranz, Lukas; Perrenoud, Julian; Seyrling, Sieghard; Verma, Rajneesh; Nishiwaki, Shiro; Romanyuk, Yaroslav E; Bilger, Gerhard; Tiwari, Ayodhya N

2011-09-18

Solar cells based on polycrystalline Cu(In,Ga)Se(2) absorber layers have yielded the highest conversion efficiency among all thin-film technologies, and the use of flexible polymer films as substrates offers several advantages in lowering manufacturing costs. However, given that conversion efficiency is crucial for cost-competitiveness, it is necessary to develop devices on flexible substrates that perform as well as those obtained on rigid substrates. Such comparable performance has not previously been achieved, primarily because polymer films require much lower substrate temperatures during absorber deposition, generally resulting in much lower efficiencies. Here we identify a strong composition gradient in the absorber layer as the main reason for inferior performance and show that, by adjusting it appropriately, very high efficiencies can be obtained. This implies that future manufacturing of highly efficient flexible solar cells could lower the cost of solar electricity and thus become a significant branch of the photovoltaic industry.

Kinetic study on UV-absorber photodegradation under different conditions

NASA Astrophysics Data System (ADS)

Bubev, Emil; Georgiev, Anton; Machkova, Maria

2016-09-01

The photodegradation kinetics of two benzophenone derivative UV-absorbers (UVAs)-BP-4 (benzophenone-4) and 4-HBP (4-hydroxybenzophenone), as additives in polyvinyl acetate (PVAc) films, were studied. Solution-processed PVAc films were irradiated in different environments in order to study oxygen and atmospheric humidity influence on UVA photodegradation. Photodegradation was traced by absorption intensity loss via UV-vis spectroscopy. Both UVAs exhibited excellent photostability in an inert atmosphere. Rate constants showed that BP-4 has better permanence in absence of oxygen. Both film types experienced rapid absorption loss, when irradiated in an oxygen containing atmosphere. UVA degradation was treated as a two-stage process. The photodegradation kinetics in the first stage agreed with the adopted complex rate law, but the second stage was best described by pseudo-first order kinetics. BP-4 exhibited better stability. Oxygen was established as the main accelerating factor for photodegradation of benzophenone derivatives UV-absorbers in thin PVAc films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abayli, D., E-mail: abayli@itu.edu.tr; Baydogan, N., E-mail: dogannil@itu.edu.tr

In this study, zirconium oxide (ZrO{sub 2}) thin film samples prepared by sol–gel method were irradiated using Co-60 radioisotope as gamma source. Then, it was investigated the ionizing effect on optical properties of ZrO{sub 2} thin film samples with the rise of the absorbed dose. The changes in the optical absorbance of ZrO{sub 2} thin films were determined by using optical transmittance and the reflectance measurements in the range between 190 – 1100 nm obtained from PG Instruments T80 UV-Vis spectrophotometer.

Low-cost thin-film absorber/evaporator for an absorption chiller. Final report, May 1992-April 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowenstein, A.; Sibilia, M.

1993-04-01

The feasibility of making the absorber and evaporator of a small lithium-bromide absorption chiller from thin plastic films was studied. Tests were performed to measure (1) pressure limitations for a plastic thin-film heat exchanger, (2) flow pressure-drop characteristics, (3) air permeation rates across the plastic films, and (4) creep characteristics of the plastic films. Initial tests were performed on heat exchangers made of either low-density polyethylene (LDPE), high-density polyethylene (HDPE), or a LDPE/HDPE blend. While initial designs for the heat exchanger failed at internal pressures of only 5 to 6 psi, the final design could withstand pressures of 34 psi.

Ultra-thin and -broadband microwave magnetic absorber enhanced by phase gradient metasurface incorporation

NASA Astrophysics Data System (ADS)

Fan, Ya; Wang, Jiafu; Li, Yongfeng; Pang, Yongqiang; Zheng, Lin; Xiang, Jiayu; Zhang, Jieqiu; Qu, Shaobo

2018-05-01

Based on the effect of anomalous reflection and refraction caused by the circularly cross-polarized phase gradient metasurface (PGM), an ultra-thin and -broadband composite absorber composed of metasurface and conventional magnetic absorbing film is proposed and demonstrated in this paper. In the case of keeping nearly the same thickness of absorbing layer, the equivalent thickness of magnetic absorbing film is enlarged by the effect of anomalous reflection and refraction, resulting in the expansion and improvement of the absorbing bandwidth and efficiency in low microwave frequency. A biarc metallic sub-cell for circularly crossed polarization is adopted to form a broadband phase gradient, by the means of rotating the Pancharatnam–Berry phases. As indicated in the experimental results, the fabricated 3.6 mm-thick absorber can averagely absorb microwave energy with the specular reflection below  ‑10 dB in the frequency interval of 2–12 GHz, which shows a good match with simulated results. Due to ultra-thin thickness and ultra-wide operating bandwidth, the proposed application of PGM in absorbing can provide an alternative way to enhance the absorbing property of current absorbing materials.

Design of optimal buffer layers for CuInGaSe2 thin-film solar cells(Conference Presentation)

NASA Astrophysics Data System (ADS)

Lordi, Vincenzo; Varley, Joel B.; He, Xiaoqing; Rockett, Angus A.; Bailey, Jeff; Zapalac, Geordie H.; Mackie, Neil; Poplavskyy, Dmitry; Bayman, Atiye

2016-09-01

Optimizing the buffer layer in manufactured thin-film PV is essential to maximize device efficiency. Here, we describe a combined synthesis, characterization, and theory effort to design optimal buffers based on the (Cd,Zn)(O,S) alloy system for CIGS devices. Optimization of buffer composition and absorber/buffer interface properties in light of several competing requirements for maximum device efficiency were performed, along with process variations to control the film and interface quality. The most relevant buffer properties controlling performance include band gap, conduction band offset with absorber, dopability, interface quality, and film crystallinity. Control of an all-PVD deposition process enabled variation of buffer composition, crystallinity, doping, and quality of the absorber/buffer interface. Analytical electron microscopy was used to characterize the film composition and morphology, while hybrid density functional theory was used to predict optimal compositions and growth parameters based on computed material properties. Process variations were developed to produce layers with controlled crystallinity, varying from amorphous to fully epitaxial, depending primarily on oxygen content. Elemental intermixing between buffer and absorber, particularly involving Cd and Cu, also is controlled and significantly affects device performance. Secondary phase formation at the interface is observed for some conditions and may be detrimental depending on the morphology. Theoretical calculations suggest optimal composition ranges for the buffer based on a suite of computed properties and drive process optimizations connected with observed film properties. Prepared by LLNL under Contract DE-AC52-07NA27344.

Photon induced facile synthesis and growth of CuInS2 absorber thin film for photovoltaic applications

NASA Astrophysics Data System (ADS)

Singh, Manjeet; Jiu, Jinting; Suganuma, Katsuaki

2016-04-01

In this paper, we demonstrate the use of high intensity pulsed light technique for the synthesis of phase pure CuInS2 (CIS) thin film at room temperature. The intense pulse of light is used to induce sintering of binary sulfides CuS and In2S3 to produce CIS phase without any direct thermal treatment. Light energy equivalent to the 706 mJ/cm2 is found to be the best energy to convert the CIS precursor film deposited at room temperature into CIS pure phase and well crystalline film. The CIS absorber film thus prepared is useful in making printed solar cell at room temperature on substrate with large area.

Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deb, K.; Bera, A.; Saha, B., E-mail: biswajit.physics@gmail.com

2016-05-23

Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline filmmore » is well suited for their applications in electronic devices.« less

Visible absorption properties of radiation exposed XR type-T radiochromic film.

PubMed

Butson, Martin J; Cheung, Tsang; Yu, Peter K N

2004-10-07

The visible absorption spectra of Gafchromic XR type-T radiochromic film have been investigated to analyse the dosimetry characteristics of the film with visible light densitometers. Common densitometers can use photospectrometry, fluorescent light (broad-band visible), helium neon (632 nm), light emitting diode (LED) or other specific bandwidth spectra. The visible absorption spectra of this film when exposed to photon radiation show peaks at 676 nm and 618 nm at 2 Gy absorbed doses which shift to slightly lower wavelengths (662 nm and 612 nm at 8 Gy absorbed dose) at higher doses. This is similar to previous models of Gafchromic film such as MD-55-2 and HS but XR type-T also includes a large absorption at lower visible wavelengths due to 'yellow' dyes placed within the film to aid with visible recognition of the film exposure level. The yellow dye band pass is produced at approximately 520 nm to 550 nm and absorbs wavelengths lower than this value within the visible spectrum. This accounts for the colour change from yellow to brown through the added absorption in the red wavelengths with radiation exposure. The film produces a relatively high dose sensitivity with up to 0.25 OD units per Gy change at 672 nm at 100 kVp x-ray energy. Variations in dose sensitivity can be achieved by varying wavelength analysis.

Spectroscopic ellipsometry investigation of the optical properties of graphene oxide dip-coated on magnetron sputtered gold thin films

NASA Astrophysics Data System (ADS)

Politano, Grazia Giuseppina; Vena, Carlo; Desiderio, Giovanni; Versace, Carlo

2018-02-01

Despite intensive investigations on graphene oxide-gold nanocomposites, the interaction of graphene oxide sheets with magnetron sputtered gold thin films has not been studied yet. The optical constants of graphene oxide thin films dip-coated on magnetron sputtered gold thin films were determined by spectroscopic ellipsometry in the [300-1000] wavelength range. Moreover, the morphologic properties of the samples were investigated by SEM analysis. Graphene oxide absorbs mainly in the ultraviolet region, but when it is dip-coated on magnetron sputtered gold thin films, its optical constants show dramatic changes, becoming absorbing in the visible region, with a peak of the extinction coefficient at 3.1 eV. Using magnetron sputtered gold thin films as a substrate for graphene oxide thin films could therefore be the key to enhance graphene oxide optical sheets' properties for several technological applications, preserving their oxygen content and avoiding the reduction process.

High Brightness and Color Contrast Displays Constructed from Nematic Droplet/Polymer Films Incorporating Pleochroic Dyes

NASA Astrophysics Data System (ADS)

Drzaic, Paul S.; Wiley, Richard C.; McCoy, James A.

1989-07-01

A new class of high-brightness, high color contrast reflective-mode displays can be constructed from nematic droplet/polymer (NCAP) films. In these films, a high order parameter pleochroic dye can be dissolved in the nematic, leading to a film with both controllable absorbance and scattering. The physics behind the operation of these films is discussed. The intrinsic optical order parameter of a guest-host mixture is related to the performance of the NCAP film. It is shown that the scattering effects inherent in these films can be used to amplify the effects of the controllable dye absorbance, leading to excellent optical performance for a reflective-mode display. A typical construction of a display cell is given, and examples of applications are discussed. Touch switches may easily be fabricated within the display, so that an integrated control/display module can be constructed.

Zincblende to Wurtzite phase shift of CdSe thin films prepared by electrochemical deposition

NASA Astrophysics Data System (ADS)

Bai, Rekha; Chaudhary, Sujeet; Pandya, Dinesh K.

2018-04-01

Cadmium selenide (CdSe) nanostructured thin films have been deposited on conducting glass substrates by potentiostatic electrochemical deposition (ECD) technique. The effect of electrolyte bath pH on the structural, morphological and optical properties of CdSe films has been investigated. Crystal structure of these films is characterized by X-ray diffraction and Raman spectroscopy which reveal polycrystalline nature of CdSe films exhibiting phase shift from zincblende to wurtzite structure with increase in bath pH. Optical studies reveal that the CdSe thin films have good absorbance in visible spectral region and they possess direct optical band gap which increases from 1.68 to 1.97 eV with increase in bath pH. The results suggest CdSe is an efficient absorber material for next generation solar cells.

Superb electromagnetic wave-absorbing composites based on large-scale graphene and carbon nanotube films.

PubMed

Li, Jinsong; Lu, Weibang; Suhr, Jonghwan; Chen, Hang; Xiao, John Q; Chou, Tsu-Wei

2017-05-24

Graphene has sparked extensive research interest for its excellent physical properties and its unique potential for application in absorption of electromagnetic waves. However, the processing of stable large-scale graphene and magnetic particles on a micrometer-thick conductive support is a formidable challenge for achieving high reflection loss and impedance matching between the absorber and free space. Herein, a novel and simple approach for the processing of a CNT film-Fe 3 O 4 -large scale graphene composite is studied. The Fe 3 O 4 particles with size in the range of 20-200 nm are uniformly aligned along the axial direction of the CNTs. The composite exhibits exceptionally high wave absorption capacity even at a very low thickness. Minimum reflection loss of -44.7 dB and absorbing bandwidth of 4.7 GHz at -10 dB are achieved in composites with one-layer graphene in six-layer CNT film-Fe 3 O 4 prepared from 0.04 M FeCl 3 . Microstructural and theoretical studies of the wave-absorbing mechanism reveal a unique Debye dipolar relaxation with an Eddy current effect in the absorbing bandwidth.

Moving beyond the limits of mass transport in liquid absorbent microfilms through the implementation of surface-induced vortices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bigham, S; Yu, DZ; Chugh, D

2014-02-01

The slow diffusion of an absorbate molecule into an absorbent often makes the absorption process a rate-limiting step in many applications. In cases involving an absorbate with a high heat of phase change, such as water absorption into a LiBr (lithium bromide) solution, the absorption rate is further slowed due to significant heating of the absorbent. Recently, it has been demonstrated that constraining a LiBr solution film by a hydrophobic porous structure enables manipulation of the solution flow thermohydraulic characteristics. Here, it is shown that mass transport mode in a constrained laminar solution flow can be changed from diffusive tomore » advective. This change in mode is accomplished through stretching and folding the laminar streamlines within the solution film via the implementation of micro-scale features on the flow channel surface. The process induces vortices within the solution film, which continuously bring concentrated solution from the bottom and middle of the solution channel to its interface with the vapor phase, thus leading to a significant enhancement in the absorption rate. The detailed physics of the involved transport processes is elucidated using the LBM (Lattice Boltzmann Method). Published by Elsevier Ltd.« less

Chemically Deposited Thin-Film Solar Cell Materials

NASA Technical Reports Server (NTRS)

Raffaelle, R.; Junek, W.; Gorse, J.; Thompson, T.; Harris, J.; Hehemann, D.; Hepp, A.; Rybicki, G.

2005-01-01

We have been working on the development of thin film photovoltaic solar cell materials that can be produced entirely by wet chemical methods on low-cost flexible substrates. P-type copper indium diselenide (CIS) absorber layers have been deposited via electrochemical deposition. Similar techniques have also allowed us to incorporate both Ga and S into the CIS structure, in order to increase its optical bandgap. The ability to deposit similar absorber layers with a variety of bandgaps is essential to our efforts to develop a multi-junction thin-film solar cell. Chemical bath deposition methods were used to deposit a cadmium sulfide (CdS) buffer layers on our CIS-based absorber layers. Window contacts were made to these CdS/CIS junctions by the electrodeposition of zinc oxide (ZnO). Structural and elemental determinations of the individual ZnO, CdS and CIS-based films via transmission spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy and energy dispersive spectroscopy will be presented. The electrical characterization of the resulting devices will be discussed.

Super-hydrophilic copper sulfide films as light absorbers for efficient solar steam generation under one sun illumination

NASA Astrophysics Data System (ADS)

Guo, Zhenzhen; Ming, Xin; Wang, Gang; Hou, Baofei; Liu, Xinghang; Mei, Tao; Li, Jinhua; Wang, Jianying; Wang, Xianbao

2018-02-01

Solar steam technology is one of the simplest, most direct and effective ways to harness solar energy through water evaporation. Here, we report the development using super-hydrophilic copper sulfide (CuS) films with double-layer structures as light absorbers for solar steam generation. In the double-layer structure system, a porous mixed cellulose ester (MCE) membrane is used as a supporting layer, which enables water to get into the CuS light absorbers through a capillary action to provide continuous water during solar steam generation. The super-hydrophilic property of the double-layer system (CuS/MCE) leads to a thinner water film close to the air-water interface where the surface temperature is sufficiently high, leading to more efficient evaporation (˜80 ± 2.5%) under one sun illumination. Furthermore, the evaporation efficiencies still keep a steady value after 15 cycles of testing. The super-hydrophilic CuS film is promising for practical application in water purification and evaporation as a light absorption material.

Utilizing strongly absorbing materials for low-loss surface-wave nonlinear optics

NASA Astrophysics Data System (ADS)

Grosse, Nicolai B.; Franz, Philipp; Heckmann, Jan; Pufahl, Karsten; Woggon, Ulrike

2018-04-01

Optical media endowed with large nonlinear susceptibilities are highly prized for their employment in frequency conversion and the generation of nonclassical states of light. Although the presence of an optical resonance can greatly increase the nonlinear response (e.g., in epsilon-near-zero materials), the non-negligible increase in linear absorption often precludes the application of such materials in nonlinear optics. Absorbing materials prepared as thin films, however, can support a low-loss surface wave: the long-range surface exciton polariton (LRSEP). Its propagation lifetime increases with greater intrinsic absorption and reduced film thickness, provided that the film is embedded in a transparent medium (symmetric cladding). We explore LRSEP propagation in a molybdenum film by way of a prism-coupling configuration. Our observations show that excitation of the LRSEP mode leads to a dramatic increase in the yield of second-harmonic generation. This implies that the LRSEP mode is an effective vehicle for utilizing the nonlinear response of absorbing materials.

Fringes in FTIR spectroscopy revisited: understanding and modelling fringes in infrared spectroscopy of thin films.

PubMed

Konevskikh, Tatiana; Ponossov, Arkadi; Blümel, Reinhold; Lukacs, Rozalia; Kohler, Achim

2015-06-21

The appearance of fringes in the infrared spectroscopy of thin films seriously hinders the interpretation of chemical bands because fringes change the relative peak heights of chemical spectral bands. Thus, for the correct interpretation of chemical absorption bands, physical properties need to be separated from chemical characteristics. In the paper at hand we revisit the theory of the scattering of infrared radiation at thin absorbing films. Although, in general, scattering and absorption are connected by a complex refractive index, we show that for the scattering of infrared radiation at thin biological films, fringes and chemical absorbance can in good approximation be treated as additive. We further introduce a model-based pre-processing technique for separating fringes from chemical absorbance by extended multiplicative signal correction (EMSC). The technique is validated by simulated and experimental FTIR spectra. It is further shown that EMSC, as opposed to other suggested filtering methods for the removal of fringes, does not remove information related to chemical absorption.

Study of structural and optical properties of PbS thin films

NASA Astrophysics Data System (ADS)

Homraruen, T.; Sudswasd, Y.; Sorod, R.; Kayunkid, N.; Yindeesuk, W.

2018-03-01

This research aimed to synthesize lead sulfide (PbS) thin films on glass slides using the successive ion layer absorption and reaction (SILAR) method. We studied the optical properties and structure of PbS thin films by changing the number of dipping cycles and the concentration of precursor solution. The results of this experiment show that different conditions have a considerable influence on the thickness and absorbance of the films. When the number of dipping cycles and the concentration of the solution are increased, film thickness and absorbance tend to become higher. The xrays diffraction pattern showed all the diffraction peaks which confirmed the face center cubic and the structure of PbS had identified. Grain size computation was used to confirm how much these conditions could be affected.

Optical, electrical, and photovoltaic properties of PbS thin films by anionic and cationic dopants

NASA Astrophysics Data System (ADS)

Cheraghizade, Mohsen; Jamali-Sheini, Farid; Yousefi, Ramin

2017-06-01

Lead sulfide (PbS) thin films were deposited by CVD method to examine the effects of anionic and cationic dopants on optical and electrical properties for photovoltaic applications. XRD diffractograms verified the formation of cubic phase of multicrystalline PbS thin films. FESEM images showed surface morphologies in nano-dimensions (rods and flowers). UV-Vis-NIR spectrum revealed absorbance in the visible and NIR regions for all samples, in which dopants decreased the intensity of absorbance. Se as an anionic dopant for PbS thin films increased electrical resistance, acceptor concentrations, and crystallite defects, and decreased flat-band voltage and depletion width. Finally, photovoltaic measurements indicated that Zn-doped PbS thin film, as a photovoltaic cell, exhibited higher conversion efficiency and external quantum efficiency (EQE).

Dosimetric characterization of GafChromic EBT film and its implication on film dosimetry quality assurance.

PubMed

Fuss, Martina; Sturtewagen, Eva; De Wagter, Carlos; Georg, Dietmar

2007-07-21

The suitability of radiochromic EBT film was studied for high-precision clinical quality assurance (QA) by identifying the dose response for a wide range of irradiation parameters typically modified in highly-conformal treatment techniques. In addition, uncertainties associated with varying irradiation conditions were determined. EBT can be used for dose assessment of absorbed dose levels as well as relative dosimetry when compared to absolute absorbed dose calibrated using ionization chamber results. For comparison, a silver halide film (Kodak EDR-2) representing the current standard in film dosimetry was included. As an initial step a measurement protocol yielding accurate and precise results was established for a flatbed transparency scanner (Epson Expression 1680 Pro) that was utilized as a film reading instrument. The light transmission measured by the scanner was found to depend on the position of the film on the scanner plate. For three film pieces irradiated with doses of 0 Gy, approximately 1 Gy and approximately 7 Gy, the pixel values measured in portrait or landscape mode differed by 4.7%, 6.2% and 10.0%, respectively. A study of 200 film pieces revealed an excellent sheet-to-sheet uniformity. On a long time scale, the optical development of irradiated EBT film consisted of a slow but steady increase of absorbance which was not observed to cease during 4 months. Sensitometric curves of EBT films obtained under reference conditions (SSD = 95 cm, FS = 5 x 5 cm(2), d = 5 cm) for 6, 10 and 25 MV photon beams did not show any energy dependence. The average separation between all curves was only 0.7%. The variation of the depth d (range 2-25 cm) in the phantom did not affect the dose response of EBT film. Also the influence of the radiation field size (range 3 x 3-40 x 40 cm(2)) on the sensitometric curve was not significant. For EDR-2 films maximum differences between the calibration curves reached 7-8% for X6MV and X25MV. Radiochromic EBT film, in combination with a flatbed scanner, presents a versatile system for high-precision dosimetry in two dimensions, provided that the intrinsic behaviour of the film reading device is taken into account. EBT film itself presents substantial improvements on formerly available models of radiographic and a radiochromic film and its dosimetric characteristics allow us to measure absorbed dose levels in a large variety of situations with a single calibration curve.

Dosimetric characterization of GafChromic EBT film and its implication on film dosimetry quality assurance

NASA Astrophysics Data System (ADS)

Fuss, Martina; Sturtewagen, Eva; DeWagter, Carlos; Georg, Dietmar

2007-07-01

The suitability of radiochromic EBT film was studied for high-precision clinical quality assurance (QA) by identifying the dose response for a wide range of irradiation parameters typically modified in highly-conformal treatment techniques. In addition, uncertainties associated with varying irradiation conditions were determined. EBT can be used for dose assessment of absorbed dose levels as well as relative dosimetry when compared to absolute absorbed dose calibrated using ionization chamber results. For comparison, a silver halide film (Kodak EDR-2) representing the current standard in film dosimetry was included. As an initial step a measurement protocol yielding accurate and precise results was established for a flatbed transparency scanner (Epson Expression 1680 Pro) that was utilized as a film reading instrument. The light transmission measured by the scanner was found to depend on the position of the film on the scanner plate. For three film pieces irradiated with doses of 0 Gy, ~1 Gy and ~7 Gy, the pixel values measured in portrait or landscape mode differed by 4.7%, 6.2% and 10.0%, respectively. A study of 200 film pieces revealed an excellent sheet-to-sheet uniformity. On a long time scale, the optical development of irradiated EBT film consisted of a slow but steady increase of absorbance which was not observed to cease during 4 months. Sensitometric curves of EBT films obtained under reference conditions (SSD = 95 cm, FS = 5 × 5 cm2, d = 5 cm) for 6, 10 and 25 MV photon beams did not show any energy dependence. The average separation between all curves was only 0.7%. The variation of the depth d (range 2-25 cm) in the phantom did not affect the dose response of EBT film. Also the influence of the radiation field size (range 3 × 3-40 × 40 cm2) on the sensitometric curve was not significant. For EDR-2 films maximum differences between the calibration curves reached 7-8% for X6MV and X25MV. Radiochromic EBT film, in combination with a flatbed scanner, presents a versatile system for high-precision dosimetry in two dimensions, provided that the intrinsic behaviour of the film reading device is taken into account. EBT film itself presents substantial improvements on formerly available models of radiographic and a radiochromic film and its dosimetric characteristics allow us to measure absorbed dose levels in a large variety of situations with a single calibration curve.

Solar energy panel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyman, M.

1980-03-04

A light-weight, low-cost and high efficiency solar panel includes a light-weight rectangular wood frame which surrounds and houses a copper absorber plate. A pair of spaced glazings, formed from plastic film materials, are disposed above the absorber to define a pair of enclosed air spaces. The lower glazing is capable of withstanding high temperatures and the upper glazing material is capable of providing good weather resistance. The material of the upper glazing extends fully about the frame to protect the entire frame from weathering. Insulation is provided beneath the absorber plate. The frame rests on top of a bottom sheetmore » of insulative foam plastic which is wrapped in a plastic envelope. The surrounding film of the outer glazing is bonded securely to the envelope to encase the entire panel within a protective sealed envelope of weather-resistant plastic film.« less

Paper-Thin Plastic Film Soaks Up Sun to Create Solar Energy

NASA Technical Reports Server (NTRS)

2006-01-01

A non-crystallized silicon known as amorphous silicon is the semiconductor material most frequently chosen for deposition, because it is a strong absorber of light. According to the U.S. Department of Energy, amorphous silicon absorbs solar radiation 40 times more efficiently than single-crystal silicon, and a thin film only about 1-micrometer (one one-millionth of a meter) thick containing amorphous silicon can absorb 90 percent of the usable light energy shining on it. Peak efficiency and significant reduction in the use of semiconductor and thin film materials translate directly into time and money savings for manufacturers. Thanks in part to NASA, thin film solar cells derived from amorphous silicon are gaining more and more attention in a market that has otherwise been dominated by mono- and poly-crystalline silicon cells for years. At Glenn Research Center, the Photovoltaic & Space Environments Branch conducts research focused on developing this type of thin film solar cell for space applications. Placing solar cells on thin film materials provides NASA with an attractively priced solution to fabricating other types of solar cells, given that thin film solar cells require significantly less semiconductor material to generate power. Using the super-lightweight solar materials also affords NASA the opportunity to cut down on payload weight during vehicle launches, as well as the weight of spacecraft being sent into orbit.

Heat and Mass Transfer of Ammonia Gas Absorption into Falling Liquid Film on a Horizontal Tube

NASA Astrophysics Data System (ADS)

Inoue, Norihiro; Yabuuchi, Hironori; Goto, Masao; Koyama, Shigeru

Heat and mass transfer coefficients during ammonia gas absorption into a falling liquid film formed by distilled water on a horizontal tube were obtained experimentally. The test absorber consists of 200 mm i.d., 600 mm long stainless steel shell, a 1 7.3 mm o.d., 14.9 mm i.d. stainless steel test tube with 600 mm working length mounted along the axis of shell, and a 12.7 mm o.d. pipe manifold of supplying the absorbent. In this paper, it was clear that heat and mass transfer coefficient could be enhanced by increasing the flow rate of absorbent and temperature difference between inlet absorbent and ammonia gas, also heat driven by the temperature difference have an effect on heat transfer of the fa1ling liquid film and mass transfer of vapor side. And the new correlation of heat transfer in dimensionless form was proposed by the temperature difference which was considered heat driven of vapor and liquid film side using a interface temperature of vapor and liquid phase. The new correlations of mass transfer on a interface of vapor and liquid phase in dimensionless form were proposed by using effect factors could be suppose from absorption phenomena.

The role of absorption in women's sexual response to erotica: a cognitive-affective investigation.

PubMed

Sheen, Jade; Koukounas, Eric

2009-01-01

This study examined the effect of absorption on women's emotional and cognitive processing of erotic film. Absorption was experimentally manipulated using 2 different sets of test session instructions. The first, participant-oriented, instruction set directed participants to absorb themselves in the erotic film presentation, imagining that they were active participants in the sexual activities depicted. The second, spectator-oriented, instruction set directed participants to observe and assess the erotic film excerpt as impartial spectators. The participant-oriented instruction set was found to elicit greater subjective absorption in women than the spectator-oriented instruction set, and women reported greater subjective sexual arousal in the former set compared with the latter. Thus, it appears that the degree to which a woman becomes absorbed in an erotic stimulus may affect her subsequent subjective sexual arousal. Also, women reported greater degrees of positive affect when they took a participant-oriented perspective than when they viewed the erotic materials as impartial spectators. Thus, participants who were highly absorbed in the erotic film excerpt were more likely to view the stimulus favorably. By contrast, the degree to which women became absorbed in the stimulus had no effect on their reported negative affect. Future directions for examining female response patterns are suggested.

Fabrication of CIS Absorber Layers with Different Thicknesses Using A Non-Vacuum Spray Coating Method.

PubMed

Diao, Chien-Chen; Kuo, Hsin-Hui; Tzou, Wen-Cheng; Chen, Yen-Lin; Yang, Cheng-Fu

2014-01-03

In this study, a new thin-film deposition process, spray coating method (SPM), was investigated to deposit the high-densified CuInSe₂ absorber layers. The spray coating method developed in this study was a non-vacuum process, based on dispersed nano-scale CuInSe₂ precursor and could offer a simple, inexpensive, and alternative formation technology for CuInSe₂ absorber layers. After spraying on Mo/glass substrates, the CuInSe₂ thin films were annealed at 550 °C by changing the annealing time from 5 min to 30 min in a selenization furnace, using N₂ as atmosphere. When the CuInSe₂ thin films were annealed, without extra Se or H₂Se gas used as the compensation source during the annealing process. The aim of this project was to investigate the influence of annealing time on the densification and crystallization of the CuInSe₂ absorber layers to optimize the quality for cost effective solar cell production. The thickness of the CuInSe₂ absorber layers could be controlled as the volume of used dispersed CuInSe₂-isopropyl alcohol solution was controlled. In this work, X-ray diffraction patterns, field emission scanning electron microscopy, and Hall parameter measurements were performed in order to verify the quality of the CuInSe₂ absorber layers obtained by the Spray Coating Method.

A new radiochromic dosimeter film

NASA Astrophysics Data System (ADS)

Sidney, L. N.; Lynch, D. C.; Willet, P. S.

By employing acid-sensitive leuco dyes in a chlorine-containing polymer matrix, a new radiochromic dosimeter film has been developed for gamma, electron beam, and ultraviolet radiation. These dosimeter films undergo a color change from colorless to royal blue, red fuchsia, or black, depending on dye selection, and have been characterized using a visible spectrophotometer over an absorbed dose range of 1 to 100 kGy. The primary features of the film are improved color stability before and after irradiation, whether stored in the dark or under artificial lights, and improved moisture resistance. The effects of absorbed dose, dose rate, and storage conditions on dosimeter performance are discussed. The dosimeter material may be produced as a free film or coated onto a transparent substrate and optionally backed with adhesive. Potential applications for these materials include gamma sterilization indicator films for food and medical products, electron beam dosimeters, and in-line radiation monitors for electron beam and ultraviolet processing.

Ag/BiOBr Film in a Rotating-Disk Reactor Containing Long-Afterglow Phosphor for Round-the-Clock Photocatalysis.

PubMed

Yin, Haibo; Chen, Xiaofang; Hou, Rujing; Zhu, Huijuan; Li, Shiqing; Huo, Yuning; Li, Hexing

2015-09-16

Ag/BiOBr film coated on the glass substrate was synthesized by a solvothermal method and a subsequent photoreduction process. Such a Ag/BiOBr film was then adhered to a hollow rotating disk filled with long-afterglow phosphor inside the chamber. The Ag/BiOBr film exhibited high photocatalytic activity for organic pollutant degradation owing to the improved visible-light harvesting and the separation of photoinduced charges. The long-afterglow phosphor could absorb the excessive daylight and emit light around 488 nm, activating the Ag/BiOBr film to realize round-the-clock photocatalysis. Because the Ag nanoparticles could extend the light absorbance of the Ag/BiOBr film to wavelengths of around 500 nm via a surface plasma resonance effect, they played a key role in realizing photocatalysis induced by long-afterglow phosphor.

Effect of Annealing Temperature on Flowerlike Cu3BiS3 Thin Films Grown by Chemical Bath Deposition

NASA Astrophysics Data System (ADS)

Deshmukh, S. G.; Patel, S. J.; Patel, K. K.; Panchal, A. K.; Kheraj, Vipul

2017-10-01

For widespread application of thin-film photovoltaic solar cells, synthesis of inexpensive absorber material is essential. In this work, deposition of ternary Cu3BiS3 absorber material, which contains abundant and environmentally benign elements, was carried out on glass substrate. Flowerlike Cu3BiS3 thin films with nanoflakes as building block were formed on glass substrate by chemical bath deposition. These films were annealed at 573 K and 673 K in sulfur ambient for structural improvement. Their structure was characterized using Raman spectroscopy, as well as their surface morphological and optical properties. The x-ray diffraction profile of as-deposited Cu3BiS3 thin film revealed amorphous structure, which transformed to orthorhombic phase after annealing. The Raman spectrum exhibited a characteristic peak at 290 cm-1. Scanning electron microscopy of as-deposited Cu3BiS3 film confirmed formation of nanoflowers with diameter of around 1052 nm. Wettability testing of as-deposited Cu3BiS3 thin film demonstrated hydrophobic nature, which became hydrophilic after annealing. The measured ultraviolet-visible (UV-Vis) absorption spectra of the Cu3BiS3 thin films gave an absorption coefficient of 105 cm-1 and direct optical bandgap of about 1.42 eV after annealing treatment. Based on all these results, such Cu3BiS3 material may have potential applications in the photovoltaic field as an absorber layer.

Aqueous Solution-Phase Selenized CuIn(S,Se)2 Thin Film Solar Cells Annealed under Inert Atmosphere.

PubMed

Oh, Yunjung; Yang, Wooseok; Kim, Jimin; Woo, Kyoohee; Moon, Jooho

2015-10-14

A nonvacuum solution-based approach can potentially be used to realize low cost, roll-to-roll fabrication of chalcopyrite CuIn(S,Se)2 (CISSe) thin film solar cells. However, most solution-based fabrication methods involve highly toxic solvents and inevitably require sulfurization and/or postselenization with hazardous H2S/H2Se gases. Herein, we introduce novel aqueous-based Cu-In-S and Se inks that contain an amine additive for producing a high-quality absorber layer. CISSe films were fabricated by simple deposition of Cu-In-S ink and Se ink followed by annealing under an inert atmosphere. Compositional and phase analyses confirmed that our simple aqueous ink-based method facilitated in-site selenization of the CIS layer. In addition, we investigated the molecular structures of our aqueous inks to determine how crystalline chalcopyrite absorber layers developed without sulfurization and/or postselenization. CISSe thin film solar cells annealed at 550 °C exhibited an efficiency of 4.55% under AM 1.5 illumination. The low-cost, nonvacuum method to deposit chalcopyrite absorber layers described here allows for safe and simple processing of thin film solar cells.

Accuracy of a dose-area product compared to an absorbed dose to water at a point in a 2 cm diameter field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dufreneix, S.; Ostrowsky, A.; Rapp, B.

Purpose: Graphite calorimeters with a core diameter larger than the beam can be used to establish dosimetric references in small fields. The dose-area product (DAP) measured can theoretically be linked to an absorbed dose at a point by the determination of a profile correction. This study aims at comparing the DAP-based protocol to the usual absorbed dose at a point protocol in a 2 cm diameter field for which both references exist. Methods: Two calorimeters were used, respectively, with a sensitive volume of 0.6 cm (for the absorbed dose at a point measurement) and 3 cm diameter (for the DAPmore » measurement). Profile correction was calculated from a 2D dose mapping using three detectors: a PinPoint chamber, a synthetic diamond, and EBT3 films. A specific protocol to read EBT3 films was implemented and the dose-rate and energy dependences were studied to assure a precise measurement, especially in the penumbra and out-of-field regions. Results: EBT3 films were found independent on dose rates over the range studied but showed a strong under-response (18%) at low energies. Depending on the dosimeter used for calculating the profile correction, a deviation of 0.8% (PinPoint chamber), 0.9% (diamond), or 1.9% (EBT3 films) was observed between the calibration coefficient derived from DAP measurements and the one directly established in terms of absorbed dose to water at a point. Conclusions: The DAP method can currently be linked to the classical dosimetric reference system based in an absorbed dose at a point only with a confidence interval of 95% (k = 2). None of the detectors studied can be used to determine an absorbed dose to water at a point from a DAP measurement with an uncertainty smaller than 1.2%.« less

Purging means and method for Xenon arc lamps

NASA Technical Reports Server (NTRS)

Miller, C. G. (Inventor)

1973-01-01

High pressure Xenon short-arc lamp with two reservoirs which are selectively connectable to the lamp's envelope is described. One reservoir contains an absorbent which will absorb both Xenon and contaminant gases such as CO2 and O2. The absorbent temperature is controlled to evacuate the envelope of both the Xenon and the contaminant gases. The temperature of the absorbent is then raised to desorb only clean Xenon while retaining the contaminant gases, thereby clearing the envelope of the contaminant gases. The second reservoir contains a gas whose specific purpose is, to remove the objectional metal film which deposits gradually on the interior surface of the lamp envelope during normal arc operation. The origin of the film is metal transferred from the cathode of the arc lamp by sputtering or other gas transfer processes.

Trap-assisted tunneling in aluminum-doped ZnO/indium oxynitride nanodot interlayer Ohmic contacts on p-GaN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ke, Wen-Cheng, E-mail: wcke@mail.ntust.edu.tw; Yang, Cheng-Yi; Lee, Fang-Wei

2015-10-21

This study developed an Ohmic contact formation method for a ZnO:Al (AZO) transparent conductive layer on p-GaN films involving the introduction of an indium oxynitride (InON) nanodot interlayer. An antisurfactant pretreatment was used to grow InON nanodots on p-GaN films in a RF magnetron sputtering system. A low specific contact resistance of 1.12 × 10{sup −4} Ω cm{sup 2} was achieved for a sample annealed at 500 °C for 30 s in nitrogen ambient and embedded with an InON nanodot interlayer with a nanodot density of 6.5 × 10{sup 8} cm{sup −2}. By contrast, a sample annealed in oxygen ambient exhibited non-Ohmic behavior. X-ray photoemission spectroscopy resultsmore » showed that the oxygen vacancy (V{sub o}) in the InON nanodots played a crucial role in carrier transport. The fitting I–V characteristic curves indicated that the hopping mechanism with an activation energy of 31.6 meV and trap site spacing of 1.1 nm dominated the carrier transport in the AZO/InON nanodot/p-GaN sample. Because of the high density of donor-like oxygen vacancy defects at the InON nanodot/p-GaN interface, positive charges from the underlying p-GaN films were absorbed at the interface. This led to positive charge accumulation, creating a narrow depletion layer; therefore, carriers from the AZO layer passed through InON nanodots by hopping transport, and subsequently tunneling through the interface to enter the p-GaN films. Thus, AZO Ohmic contact can be formed on p-GaN films by embedding an InON nanodot interlayer to facilitate trap-assisted tunneling.« less

Plant uptake-assisted round-the-clock photocatalysis for complete purification of aquaculture wastewater using sunlight.

PubMed

Bian, Zhenfeng; Cao, Fenglei; Zhu, Jian; Li, Hexing

2015-02-17

A novel reactor equipped with solar batteries, Bi2O3/TiO2 film photocatalyst, and celery plant was designed and used for purification of aquaculture wastewater. The Bi2O3/TiO2 film photocatalyst started photocatalytic degradation of organonitrogen compounds under irradiation of sunlight. Meanwhile, the solar batteries absorbed and converted excess sunlight into electric energy and then started UV lamps at night, leading to round-the-clock photocatalysis. Subsequently, the inorganic nitrogen species including NH4(+), NO2(-), and NO3(-) resulting from photocatalytic degradation of the organonitrogen compounds could subsequently be uptaken by the celery plant as the fertilizer to reduce the secondary pollution. It was found that, after 24 h circulation, both organonitrogen compounds and NO2(-) species were completely removed, while NH4(+) and NO3(-) contents also decreased by 30% and 50%, respectively. The reactor could be used repetitively, showing a good potential in practical application.

Alkyl chitosan film-high strength, functional biomaterials.

PubMed

Lu, Li; Xing, Cao; Xin, Shen; Shitao, Yu; Feng, Su; Shiwei, Liu; Fusheng, Liu; Congxia, Xie

2017-11-01

Biofilm with strong tensile strength is a topic item in the area of tissue engineering, medicine engineering, and so forth. Here we introduced an alkyl chitosan film with strong tensile strength and its possibility for an absorbable anticoagulation material in vivo was tested in the series of blood test, such as dynamic coagulation time, plasma recalcification time and hemolysis. Alkyl chitosan film was a better biomaterial than traditional chitosan film in the anticoagulation, tissue compatibility and cell compatibility. The unique trait of alkyl chitosan film may be for its greater contact angle and hydrophobicity ability to reduce the adsorption capacity for the blood component and the activity of fibrinolytic enzymes, enhance the antibacterial capacity than chitosan film. Moreover, none of chitosan film or butyl chitosan film exhibited quick inflammation or other disadvantage and degraded quickly by implanted test. Therefore, Alkyl chitosan film is of prospective properties as an implantable, absorbable agent for tissue heals, and this material need further research. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3034-3041, 2017. © 2017 Wiley Periodicals, Inc.

Polyaniline-stabilized electromagnetic wave absorption composites of reduced graphene oxide on magnetic carbon nanotube film

NASA Astrophysics Data System (ADS)

Li, Jinsong; Duan, Yan; Lu, Weibang; Chou, Tsu-Wei

2018-04-01

A multi-layered composite with exceptionally high electromagnetic wave-absorbing capacity and performance stability was fabricated via the facile electrophoresis of a reduced graphene oxide network on carbon nanotube (CNT)-Fe3O4-polyaniline (PANI) film. Minimum reflection loss (RL) of -53.2 dB and absorbing bandwidth of 5.87 GHz (< -10 dB) are achieved, surpassing most recently reported CNT- and graphene-based absorbers. In particular, comparing to the original composites, the minimum RL and bandwidth (< -10 dB) maintains 82.5% and 99.7%, respectively, after 20 h charge/discharge cycling, demonstrating high environmental suitability.

Research Update: Emerging chalcostibite absorbers for thin-film solar cells

DOE PAGES

de Souza Lucas, Francisco Willian; Zakutayev, Andriy

2018-06-04

Copper antimony chalcogenides CuSbCh 2 (Ch=S, Se) are an emerging family of absorbers studied for thin-film solar cells. These non-toxic and Earth-abundant materials show a layered low-dimensional chalcostibite crystal structure, leading to interesting optoelectronic properties for applications in photovoltaic (PV) devices. This research update describes the CuSbCh 2 crystallographic structures, synthesis methods, competing phases, band structures, optoelectronic properties, point defects, carrier dynamics, and interface band offsets, based on experimental and theoretical data. Correlations between these absorber properties and PV device performance are discussed, and opportunities for further increase in the efficiency of the chalcostibite PV devices are highlighted.

Research Update: Emerging chalcostibite absorbers for thin-film solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Souza Lucas, Francisco Willian; Zakutayev, Andriy

Copper antimony chalcogenides CuSbCh 2 (Ch=S, Se) are an emerging family of absorbers studied for thin-film solar cells. These non-toxic and Earth-abundant materials show a layered low-dimensional chalcostibite crystal structure, leading to interesting optoelectronic properties for applications in photovoltaic (PV) devices. This research update describes the CuSbCh 2 crystallographic structures, synthesis methods, competing phases, band structures, optoelectronic properties, point defects, carrier dynamics, and interface band offsets, based on experimental and theoretical data. Correlations between these absorber properties and PV device performance are discussed, and opportunities for further increase in the efficiency of the chalcostibite PV devices are highlighted.

Semiconductor meta-surface based perfect light absorber

NASA Astrophysics Data System (ADS)

Liu, Guiqiang; Nie, Yiyou; Fu, Guolan; Liu, Xiaoshan; Liu, Yi; Tang, Li; Liu, Zhengqi

2017-04-01

We numerically proposed and demonstrated a semiconductor meta-surface light absorber, which consists of a silicon patches array on a silicon thin-film and an opaque silver substrate. The Mie resonances of the silicon patches and the fundamental cavity mode of the ultra-thin silicon film couple strongly to the incident optical field, leading to a multi-band perfect absorption. The maximal absorption is above 99.5% and the absorption is polarization-independent. Moreover, the absorption behavior is scalable in the frequency region via tuning the structural parameters. These features hold the absorber platform with wide applications in optoelectronics such as hot-electron excitation and photo-detection.

Influence of alkali metals (Na, Li, Rb) on the performance of electrostatic spray-assisted vapor deposited Cu2ZnSn(S,Se)4 solar cells

NASA Astrophysics Data System (ADS)

Altamura, Giovanni; Wang, Mingqing; Choy, Kwang-Leong

2016-02-01

Electrostatic Spray-Assisted Vapor Deposition (ESAVD) is a non-vacuum and cost-effective method to deposit metal oxide, various sulphide and chalcogenide at large scale. In this work, ESAVD was used to deposit Cu2ZnSn(S1-xSex)4 (CZTSSe) absorber. Different alkali metals like Na, Li and Rb were incorporated in CZTSSe compounds to further improve the photovoltaic performances of related devices. In addition, to the best of our knowledge, no experimental study has been carried out to test the effect of Li and Rb incorporation in CZTSSe solar cells. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and glow discharge spectroscopy have been used to characterize the phase purity, morphology and composition of as-deposited CZTSSe thin films. Photovoltaic properties of the resulting devices were determined by completing the solar cells as follows: Mo/CZTSSe/CdS/i-ZnO/Al:ZnO/Ni/Al. The results showed that Li, Na and Rb incorporation can increase power conversion efficiency of CZTS devices up to 5.5%. The introduction of a thiourea treatment, has improved the quality of the absorber|buffer interface, pushed the device efficiency up to 6.3% which is at the moment the best reported result for ESAVD deposited CZTSSe solar cells.

Fabrication and characterization of high mobility spin-coated zinc oxide thin film transistors

NASA Astrophysics Data System (ADS)

Singh, Shaivalini; Chakrabarti, P.

2012-10-01

A ZnO based thin film transistor (TFT) with bottom-gate configuration and SiO2 as insulating layer has been fabricated and characterized. The ZnO thin film was prepared by spin coating the sol-gel solution on the p-type Si wafers. The optical and structural properties of ZnO films were investigated using UV measurements and scanning electron microscope (SEM). The result of UV-visible study confirms that the films have a good absorbance in UV region and relatively low absorbance in the visible region. The TFT exhibited an off-current of 2.5×10-7 A. The values of field effect channel mobility and on/off current ratio extracted for the device, measured 11 cm2/V.s and ~102 respectively. The value of threshold voltage was found to be 1.3 V.

Influence of Te and Se doping on ZnO films growth by SILAR method

NASA Astrophysics Data System (ADS)

Güney, Harun; Duman, Ćaǧlar

2016-04-01

The AIP Successive ionic layer adsorption and reaction (SILAR) is an economic and simple method to growth thin films. In this study, SILAR method is used to growth Selenium (Se) and Tellurium (Te) doped zinc oxide (ZnO) thin films with different doping rates. For characterization of the films X-ray diffraction (XRD), absorbance and scanning electron microscopy (SEM) are used. XRD results are showed well-defined strongly (002) oriented crystal structure for all samples. Also, absorbance measurements show, Te and Se concentration are proportional and inversely proportional with band gap energy, respectively. SEM measurements show that the surface morphology and thickness of the material varied with Se and/or Te and varying concentrations.

Influence of Te and Se doping on ZnO films growth by SILAR method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Güney, Harun, E-mail: harunguney25@hotmail.com; Duman, Çağlar, E-mail: caglarduman@erzurum.edu.tr

2016-04-18

The AIP Successive ionic layer adsorption and reaction (SILAR) is an economic and simple method to growth thin films. In this study, SILAR method is used to growth Selenium (Se) and Tellurium (Te) doped zinc oxide (ZnO) thin films with different doping rates. For characterization of the films X-ray diffraction (XRD), absorbance and scanning electron microscopy (SEM) are used. XRD results are showed well-defined strongly (002) oriented crystal structure for all samples. Also, absorbance measurements show, Te and Se concentration are proportional and inversely proportional with band gap energy, respectively. SEM measurements show that the surface morphology and thickness ofmore » the material varied with Se and/or Te and varying concentrations.« less

The New Film Technologies: Computerized Video-Assisted Film Production.

ERIC Educational Resources Information Center

Mott, Donald R.

Over the past few years, video technology has been used to assist film directors after they have shot a scene, to control costs, and to create special effects, especially computer assisted graphics. At present, a computer based editing system called "Film 5" combines computer technology and video tape with film to save as much as 50% of…

Intensity tunable infrared broadband absorbers based on VO2 phase transition using planar layered thin films

PubMed Central

Kocer, Hasan; Butun, Serkan; Palacios, Edgar; Liu, Zizhuo; Tongay, Sefaattin; Fu, Deyi; Wang, Kevin; Wu, Junqiao; Aydin, Koray

2015-01-01

Plasmonic and metamaterial based nano/micro-structured materials enable spectrally selective resonant absorption, where the resonant bandwidth and absorption intensity can be engineered by controlling the size and geometry of nanostructures. Here, we demonstrate a simple, lithography-free approach for obtaining a resonant and dynamically tunable broadband absorber based on vanadium dioxide (VO2) phase transition. Using planar layered thin film structures, where top layer is chosen to be an ultrathin (20 nm) VO2 film, we demonstrate broadband IR light absorption tuning (from ~90% to ~30% in measured absorption) over the entire mid-wavelength infrared spectrum. Our numerical and experimental results indicate that the bandwidth of the absorption bands can be controlled by changing the dielectric spacer layer thickness. Broadband tunable absorbers can find applications in absorption filters, thermal emitters, thermophotovoltaics and sensing. PMID:26294085

On the Validity of Beer-Lambert Law and its Significance for Sunscreens.

PubMed

Herzog, Bernd; Schultheiss, Amélie; Giesinger, Jochen

2018-03-01

The sun protection factor (SPF) is the most important quantity to characterize the performance of sunscreens. As the standard method for its determination is based on clinical trials involving irradiation of human volunteers, calculations of sunscreen performance have become quite popular to reduce the number of in vivo studies. Such simulations imply the calculation of UV transmittance of the sunscreen film using the amounts and spectroscopic properties of the UV absorbers employed, and presuppose the validity of the Beer-Lambert law. As sunscreen films on human skin can contain considerable concentrations of UV absorbers, it is questioned whether the Beer-Lambert law is still valid for these systems. The results of this work show that the validity of the Beer-Lambert law is still given at the high concentrations at which UV absorbers occur in sunscreen films on human skin. © 2017 The American Society of Photobiology.

Development of Multifunctional Active Film and Its Application in Modified Atmosphere Packaging of Shiitake Mushrooms.

PubMed

Wang, Hong Jiang; An, Duck Soon; Lee, Dong Sun

2016-09-01

Agar-based films with multiple functions (CO 2 absorption, water vapor absorption, and antimicrobial activity) were developed, tested for their properties, and then applied to the packaging of fresh shiitake mushrooms as an insert label. The films were cast from an agar-based aqueous solution containing a dissolving plasticizer (glycerol), a CO 2 absorbent (sodium carbonate [SC] alone or a combination of SC and sodium glycinate [SC-SG]), and a volatile antimicrobial agent (carvacrol [CRV]). The agar of the film matrix is designed to serve as a water vapor absorbent. The multifunctional films tended to have poor mechanical properties, with a hard texture and an opaque and yellowish color. The CO 2 absorbent, either SC alone or SC-SG, affected CRV retention and release along with the CO 2 and water vapor absorption behavior. Both films (SC-CRV and SC-SG-CRV films) showed good inhibitory effects against Pseudomonas fluorescens and Saccharomyces cerevisiae . SC-CRV film had a higher and faster CO 2 absorption property, higher retention and extended release of CRV, and lower and slower water vapor absorption and was assessed to be better suited for use in shiitake mushroom packaging. The packaging in which the SC-CRV film with an appropriate amount of CRV was used as an insert label was able to generate the desired atmosphere and less moisture condensation inside the package, producing the best preservation of quality in terms of mushroom color, firmness, flavor score, and microbial counts after 6 days of storage at 10°C. A tailored modified atmosphere packaging system using multifunctional film would be useful in the preservation of CO 2 -sensitive fresh commodities.

Identifying barriers to charge-carriers in the bulk and surface regions of Cu2ZnSnS4 nanocrystal films by x-ray absorption fine structures (XAFSs)

NASA Astrophysics Data System (ADS)

Turnbull, Matthew J.; Vaccarello, Daniel; Yiu, Yun Mui; Sham, Tsun-Kong; Ding, Zhifeng

2016-11-01

Solar cell performance is most affected by the quality of the light absorber layer. For thin-film devices, this becomes a two-fold problem of maintaining a low-cost design with well-ordered nanocrystal (NC) structure. The use of Cu2ZnSnS4 (CZTS) NCs as the light absorber films forms an ideal low-cost design, but the quaternary structure makes it difficult to maintain a well-ordered layer without the use of high-temperature treatments. There is little understanding of how CZTS NC structures affect the photoconversion efficiency, the charge-carriers, and therefore the performance of the device manufactured from it. To examine these relationships, the measured photoresponse from the photo-generation of charge-carrier electron-hole pairs was compared against the crystal structure, as short-range and long-range crystal orders for the films. The photoresponse simplifies the electronic properties into three basic steps that can be associated with changes in energy levels within the band structure. These changes result in the formation of barriers to charge-carrier flow. The extent of these barriers was determined using synchrotron-based X-ray absorbance fine structure to probe the individual metal centers in the film, and comparing these to molecular simulations of the ideal extended x-ray absorbance fine structure scattering. This allowed for the quantification of bond lengths, and thus an interpretation of the distortions in the crystal lattice. The various characteristics of the photoresponse were then correlated to the crystallographic order and used to gain physical insight into barriers to charge-carriers in the bulk and surface regions of CZTS films.

Controlled Crystal Grain Growth in Mixed Cation-Halide Perovskite by Evaporated Solvent Vapor Recycling Method for High Efficiency Solar Cells.

PubMed

Numata, Youhei; Kogo, Atsushi; Udagawa, Yosuke; Kunugita, Hideyuki; Ema, Kazuhiro; Sanehira, Yoshitaka; Miyasaka, Tsutomu

2017-06-07

We developed a new and simple solvent vapor-assisted thermal annealing (VA) procedure which can reduce grain boundaries in a perovskite film for fabricating highly efficient perovskite solar cells (PSCs). By recycling of solvent molecules evaporated from an as-prepared perovskite film as a VA vapor source, named the pot-roast VA (PR-VA) method, finely controlled and reproducible device fabrication was achieved for formamidinium (FA) and methylammonium (MA) mixed cation-halide perovskite (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 . The mixed perovskite was crystallized on a low-temperature prepared brookite TiO 2 mesoporous scaffold. When exposed to very dilute solvent vapor, small grains in the perovskite film gradually unified into large grains, resulting in grain boundaries which were highly reduced and improvement of photovoltaic performance in PSC. PR-VA-treated large grain perovskite absorbers exhibited stable photocurrent-voltage performance with high fill factor and suppressed hysteresis, achieving the best conversion efficiency of 18.5% for a 5 × 5 mm 2 device and 15.2% for a 1.0 × 1.0 cm 2 device.

Wavelength-versatile graphene-gold film saturable absorber mirror for ultra-broadband mode-locking of bulk lasers.

PubMed

Ma, Jie; Xie, Guoqiang; Lv, Peng; Gao, Wenlan; Yuan, Peng; Qian, Liejia; Griebner, Uwe; Petrov, Valentin; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

2014-05-23

An ultra-broadband graphene-gold film saturable absorber mirror (GG-SAM) with a spectral coverage exceeding 1300 nm is experimentally demonstrated for mode-locking of bulk solid-state lasers. Owing to the p-type doping effect caused by graphene-gold film interaction, the graphene on gold-film substrate shows a remarkably lower light absorption relative to pristine graphene, which is very helpful to achieve continuous-wave mode-locking in low-gain bulk lasers. Using the GG-SAM sample, stable mode-locking is realized in a Yb:YCOB bulk laser near 1 μm, a Tm:CLNGG bulk laser near 2 μm and a Cr:ZnSe bulk laser near 2.4 μm. The saturable absorption is characterised at an intermediate wavelength of 1.56 μm by pump-probe measurements. The as-fabricated GG-SAM with ultra-broad bandwidth, ultrafast recovery time, low absorption, and low cost has great potential as a universal saturable absorber mirror for mode-locking of various bulk lasers with unprecedented spectral coverage.

Wavelength-Versatile Graphene-Gold Film Saturable Absorber Mirror for Ultra-Broadband Mode-Locking of Bulk Lasers

PubMed Central

Ma, Jie; Xie, Guoqiang; Lv, Peng; Gao, Wenlan; Yuan, Peng; Qian, Liejia; Griebner, Uwe; Petrov, Valentin; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

2014-01-01

An ultra-broadband graphene-gold film saturable absorber mirror (GG-SAM) with a spectral coverage exceeding 1300 nm is experimentally demonstrated for mode-locking of bulk solid-state lasers. Owing to the p-type doping effect caused by graphene-gold film interaction, the graphene on gold-film substrate shows a remarkably lower light absorption relative to pristine graphene, which is very helpful to achieve continuous-wave mode-locking in low-gain bulk lasers. Using the GG-SAM sample, stable mode-locking is realized in a Yb:YCOB bulk laser near 1 μm, a Tm:CLNGG bulk laser near 2 μm and a Cr:ZnSe bulk laser near 2.4 μm. The saturable absorption is characterised at an intermediate wavelength of 1.56 μm by pump-probe measurements. The as-fabricated GG-SAM with ultra-broad bandwidth, ultrafast recovery time, low absorption, and low cost has great potential as a universal saturable absorber mirror for mode-locking of various bulk lasers with unprecedented spectral coverage. PMID:24853072

Thermalization of X-rays in evaporated tin and bismuth films used as the absorbing materials in X-ray calorimeters

NASA Astrophysics Data System (ADS)

Stahle, C. K.; Kelley, R. L.; Moseley, S. H.; Szymkowiak, A. E.; Juda, M.; McCammon, D.; Zhang, J.

1993-11-01

We have investigated the use of evaporated tin and bismuth films as the absorbing materials in X-ray calorimeters. When the films were deposited directly on monolithic silicon calorimeters, the output signal from both Sn and Bi devices was strongly dependent on the location of the absorption event relative to the ion-implanted thermistors, presumably indicating thermistor sensitivity to a non-thermal spectrum of phonons. With Sn films we also observed that a component of the thermalization proceeded slowly, relative to a complete thermalization reference. The thermalization function could be modified by trapping magnetic flux within the film. In order to distinguish thermalization effects in the films from the thermistor sensitivity to energetic phonons, we deposited Sn and Bi films on thin Si substrates which we then affixed to calorimeters using epoxy. With glued Sn films, we were able to attain as good as 13.6 eV resolution of 6 keV X-rays with no excess broadening of the line beyond the width of the baseline, while similarly made Bi devices showed excess broadening.

Fabrication of CIS Absorber Layers with Different Thicknesses Using A Non-Vacuum Spray Coating Method

PubMed Central

Diao, Chien-Chen; Kuo, Hsin-Hui; Tzou, Wen-Cheng; Chen, Yen-Lin; Yang, Cheng-Fu

2014-01-01

In this study, a new thin-film deposition process, spray coating method (SPM), was investigated to deposit the high-densified CuInSe2 absorber layers. The spray coating method developed in this study was a non-vacuum process, based on dispersed nano-scale CuInSe2 precursor and could offer a simple, inexpensive, and alternative formation technology for CuInSe2 absorber layers. After spraying on Mo/glass substrates, the CuInSe2 thin films were annealed at 550 °C by changing the annealing time from 5 min to 30 min in a selenization furnace, using N2 as atmosphere. When the CuInSe2 thin films were annealed, without extra Se or H2Se gas used as the compensation source during the annealing process. The aim of this project was to investigate the influence of annealing time on the densification and crystallization of the CuInSe2 absorber layers to optimize the quality for cost effective solar cell production. The thickness of the CuInSe2 absorber layers could be controlled as the volume of used dispersed CuInSe2-isopropyl alcohol solution was controlled. In this work, X-ray diffraction patterns, field emission scanning electron microscopy, and Hall parameter measurements were performed in order to verify the quality of the CuInSe2 absorber layers obtained by the Spray Coating Method. PMID:28788451

Plasticization of Poly (lactic) acid Film as a Potential Coating Material

NASA Astrophysics Data System (ADS)

Yang, Ping; Li, Hua; Liu, Qingsong; Dong, Hongbiao; Duan, Yafei; Zhang, Jiasong

2018-01-01

PLA-based composite films with different plasticizers, such as polyethylene glycol (PEG) and Tributyl citrate (TBC), were prepared using a solvent casting method and their machanical, water absorbency and NO3 --N permeability properties were tested. Tensile strength, elongation at break, water absorbency and NO3 --N permeability of neat PLA film were 1.99 ± 0.04 MPa, 2.7 ± 0.46%, 29.33 ± 0.3% and 216.03 ± 19.92 mg·L-1·m-2·h-1, respectively. After the addition of plasticizers the tensile strength were decreased, tensile strength of flims added 40wt% TBC and PEG decreased by 59.3% and 52.26%. While the elongation at break of the PLA film gradually increased. The elongation at break reached the value of 23.96±0.48% and 38.55±1.66% for the films added PEG and TBC respectively at the concentration of 40wt%. Water absorbency decreased as the increase of plasticizers. The NO3 --N permeability attained a maximum of 300.05±10.47 and 270.97±14.54 mg·L-1·m-2·h-1 for films added PEG and TBC at the concentration of 10 wt % respectively. Considered the NO3 --N permeability, PEG at 10wt% seemed the better plasticizer for PLA used in control release of fertilizer.

Change Spectrum Characteristics Modification of Films Deposited by Magnetron Sputtering with the Assistance of Argon Ions Beam

NASA Astrophysics Data System (ADS)

Umnov, S.; Asainov, O.

2015-04-01

Thin aluminum films were prepared using the method of magnetron sputtering with and without argon ion beam assistance. The influence of argon ion beam on the reflectivity in the UV range and the structure of aluminum films was studied. The structure of the films was studied by transmission electron microscopy (TEM), X-ray diffractometry (XRD) and atomic- force microscope (AFM). The study has shown that the films deposed with the assistance of the argon ion beam have more significant microstresses associated with an increase of crystallites microstructure defects as compared to the films deposed without ion assistance. Comparison of the measured reflectivity of aluminum films deposed without and with the assistance of the ion beam has shown that the films characterized by a higher level of microstructure def ects have increased reflectivity in the UV range. The studies suggest that the defects of thin aluminum films crystal structure influence its optical properties.

Characterization of Cu(In,Ga)Se 2 (CIGS) films with varying gallium ratios

DOE PAGES

Claypoole, Jesse; Peace, Bernadette; Sun, Neville; ...

2015-09-05

Cu(In 1–x,Ga x)Se 2 (CIGS) absorber layers were deposited on molybdenum (Mo) coated soda-lime glass substrates with varying Ga content (described as Ga/(In + Ga) ratios) with respect to depth. As the responsible mechanisms for the limitation of the performance of the CIGS solar cells with high Ga contents are not well understood, the goal of this work was to investigate different properties of CIGS absorber films with Ga/(In + Ga) ratios varied between 0.29 and 0.41 (as determined by X-ray florescence spectroscopy (XRF)) in order to better understand the role that the Ga content has on film quality. Themore » Ga grading in the CIGS layer has the effect causing a higher band gap toward the surface and Mo contact while the band gap in the middle of the CIGS layer is lower. Also, a wider and larger Ga/(In + Ga) grading dip located deeper in the CIGS absorber layers tend to produce larger grains in the regions of the films that have lower Ga/(In + Ga) ratios. Moreover, it was found that surface roughness decreases from 51.2 nm to 41.0 nm with increasing Ga/(In + Ga) ratios. Furthermore, the surface roughness generally decreases if the Ga grading occurs deeper in the absorber layer.« less

Thin film solar cells by selenization sulfurization using diethyl selenium as a selenium precursor

DOEpatents

Dhere, Neelkanth G.; Kadam, Ankur A.

2009-12-15

A method of forming a CIGSS absorber layer includes the steps of providing a metal precursor, and selenizing the metal precursor using diethyl selenium to form a selenized metal precursor layer (CIGSS absorber layer). A high efficiency solar cell includes a CIGSS absorber layer formed by a process including selenizing a metal precursor using diethyl selenium to form the CIGSS absorber layer.

Radiation Sensitivity of Soluble Polysilane Derivatives: Science and Applications

DTIC Science & Technology

1988-08-01

sigma bonded, all substituted silane polymers absorb strongly in the UV-visible region. Their absorption spectra depend to some extent on the nature...of the substituents. In this regard alkyl substituted, atatic, amphorous materials absorb from 300-325 nm with sterically bulky groups producing a...cases, the polysilane is the primary absorber of the incident radiation. Interestingly, when 3, which absorbs at -400 inm, was incorporated into a film

Solution-proceed Air-stable Copper Bismuth Iodide CuBiI₄ for Photovoltaics.

PubMed

Hu, Zhaosheng; Wang, Zhen; Kapil, Gaurav; Ma, Tingli; Iikubo, Satoshi; Minemoto, Takashi; Yoshino, Kenji; Toyoda, Taro; Shen, Qing; Hayase, Shuzi

2018-06-19

Bismuth based solar cells have been under intensive interest as an efficient non-toxic absorber in photovoltaics. Within this new family of semiconductors, we herein, report a new, long-term stable material copper bismuth iodide (CuBiI₄). A solution-processed method is provided under air atmosphere. The adopted HI assisted Dimethylacetamide (DMA) co-solvent can completely dissolve CuI and BiI₃ powders with high concentration compared to other organic solvent. Moreover, high vapor pressure of Tributyl phosphate, we select for the solvent vapor annealing (SVA), enables the whole low-temperature (≤70⁰C) film preparation. It results in a stable, uniform dense CuBiI₄ film. The average grains size increasing with precursor concentration, greatly enlarge the PL life time and hall mobility. And carrier lifetime of 3.03 ns as well as an appreciable hall mobility of 110 cm²/Vs were obtained. X-ray diffraction illustrates that the crystal structure is cubic (space group Fd3m) and favored in [1, 1, 1] direction. Moreover, the photovoltaic performance of CuBiI₄ was also investigated. A wide-bandgap (2.67 eV) solar cell with 0.82 % performance is presented, which shows an excellent long-term stability at least over 1008 hours under ambient conditions. This air-stable material may give an application in future tandem solar cells as a stable short-wavelength light absorber. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Layer-by-Layer Assembled Films of Perylene Diimide- and Squaraine-Containing Metal-Organic Frameworks- like Materials: Solar Energy Capture and Directional Energy Transfer

DOE PAGES

Park, Hea Jung; So, Monica C.; Gosztola, David J.

2016-09-28

We demonstrate that thin films of metal organic framework (MOF)-like materials, containing two perylenedlimides (PDICl4, PDIOPh2) and a squaraine dye (S1); can be fabricated by, layer-by-layer assembly (LbL). Interestingly, these LbL films absorb across the visible light region (400-750 nm) and facilitate directional energy transfer. Due to the high spectral overlap and oriented transition dipole moments of the donor (PDICl4 and PDIOPh2) and acceptor (S1) components, directional long-range energy transfer from the bluest to reddest absorber was successfully demonstrated in the multicomponent MOF-like films. These findings have significant implications for the development of solar energy conversion devices based on MOFs.

Optical and structural properties of CsI thin film photocathode

NASA Astrophysics Data System (ADS)

Triloki; Rai, R.; Singh, B. K.

2015-06-01

In the present work, the performance of a cesium iodide thin film photocathode is studied in detail. The optical absorbance of cesium iodide films has been analyzed in the spectral range from 190 nm to 900 nm. The optical band gap energy of 500 nm thick cesium iodide film is calculated from the absorbance data using a Tauc plot. The refractive index is estimated from the envelope plot of transmittance data using Swanepoel's method. The absolute quantum efficiency measurement has been carried out in the wavelength range from 150 nm to 200 nm. The crystallographic nature and surface morphology are investigated by X-ray diffraction and transmission electron microscopy techniques. In addition, the elemental composition result obtained by energy dispersive X-ray analysis is also reported in the present work.

HIGH-k GATE DIELECTRIC: AMORPHOUS Ta/La2O3 FILMS GROWN ON Si AT LOW PRESSURE

NASA Astrophysics Data System (ADS)

Bahari, Ali; Khorshidi, Zahra

2014-09-01

In the present study, Ta/La2O3 films (La2O3 doped with Ta2O5) as a gate dielectric were prepared using a sol-gel method at low pressure. Ta/La2O3 film has some hopeful properties as a gate dielectric of logic device. The structure and morphology of Ta/La2O3 films were studied using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrical properties of films were performed using capacitance-voltage (C-V) and current density-voltage (J-V) measurements. The optical bandgap of samples was studied by UV-visible optical absorbance measurement. The optical bandgap, Eopt, is determined from the absorbance spectra. The obtained results show that Ta/La2O3 film as a good gate dielectric has amorphous structure, good thermal stability, high dielectric constant (≈ 25), low leakage current and wide bandgap (≈ 4.7 eV).

Structural, optical and electrical properties of copper antimony sulfide thin films grown by a citrate-assisted single chemical bath deposition

NASA Astrophysics Data System (ADS)

Loranca-Ramos, F. E.; Diliegros-Godines, C. J.; Silva González, R.; Pal, Mou

2018-01-01

Copper antimony sulfide (CAS) has been proposed as low toxicity and earth abundant absorber materials for thin film photovoltaics due to their suitable optical band gap, high absorption coefficient and p-type electrical conductivity. The present work reports the formation of copper antimony sulfide by chemical bath deposition using sodium citrate as a complexing agent. We show that by tuning the annealing condition, one can obtain either chalcostibite or tetrahedrite phase. However, the main challenge was co-deposition of copper and antimony as ternary sulfides from a single chemical bath due to the distinct chemical behavior of these metals. The as-deposited films were subjected to several trials of thermal treatment using different temperatures and time to find the optimized annealing condition. The films were characterized by different techniques including Raman spectroscopy, X-ray diffraction (XRD), profilometer, scanning electron microscopy (SEM), UV-vis spectrophotometer, and Hall Effect measurements. The results show that the formation of chalcostibite and tetrahedrite phases is highly sensitive to annealing conditions. The electrical properties obtained for the chalcostibite films varied as the annealing temperature increases from 280 to 350 °C: hole concentration (n) = 1017-1018 cm-3, resistivity (ρ) = 1.74-2.14 Ωcm and carrier mobility (μ) = 4.7-9.26 cm2/Vseg. While for the tetrahedrite films, the electrical properties were n = 5 × 1019 cm-3, μ = 18.24 cm2/Vseg, and ρ = 5.8 × 10-3 Ωcm. A possible mechanism for the formation of ternary copper antimony sulfide has also been proposed.

Fabrication and characterization of differentiated aramid nanofibers and transparent films

NASA Astrophysics Data System (ADS)

Luo, Jingjing; Zhang, Meiyun; Yang, Bin; Liu, Guodong; Song, Shunxi

2018-03-01

Aramid nanofibers (ANFs) frequently are employed as versatile building blocks for constructing high-performance nanocomposites due to its structural and performance superiority. In this paper, the different ANFs and ANF films derived from the typical aramid yarns, chopped fiber, pulp fiber and fibrid fiber, respectively, were fabricated through deprotonation with potassium hydroxide in dimethyl sulphoxide, protonation with deionized water and vacuum-assisted filtration. The physical tests such as tensile test, ultraviolet transmittance and absorbance, thermogravimetric analysis were executed to evaluate and contrast the thermodynamic and optical performances of these differentiated ANFs and ANF films. The analytical results suggested that ANFs films prepared by the different forms of aramid macrofibers presented with differentiated properties such as mechanical behaviors, transparencies and flexibilities. And also it was found that the oversized nanofiber in length led to the formation of flocculation which was adverse for ANFs films in the formation of high strength. Whereas, small diameter just facilitated for the achievement of high stiffness and transparency. By contrast, the ANFs films made from chopped nanofiber, with aspect ratio of 200-500, exhibited good transparency, thermal stability and mechanical properties with transmittance value of 83%, TG10% around 521 °C, ultimate strength (σ) of 103.41 MPa, stiffness (E) of 4.70 GPa and strain at break of 5.56%. This work offers an alternative nanoscale building block as an effective nanofiller for preparing high-performance nanocomposites with different requirements in the potential fields such as transparent coating and flexible electrode or display materials, battery separator and microporous membrane.

Spray CVD for Making Solar-Cell Absorber Layers

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Harris, Jerry; Jin, Michael H.; Hepp, Aloysius

2007-01-01

Spray chemical vapor deposition (spray CVD) processes of a special type have been investigated for use in making CuInS2 absorber layers of thin-film solar photovoltaic cells from either of two subclasses of precursor compounds: [(PBu3) 2Cu(SEt)2In(SEt)2] or [(PPh3)2Cu(SEt)2 In(SEt)2]. The CuInS2 films produced in the experiments have been characterized by x-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and four-point-probe electrical tests.

Fabrication of solution processed 3D nanostructured CuInGaS₂ thin film solar cells.

PubMed

Chu, Van Ben; Cho, Jin Woo; Park, Se Jin; Hwang, Yun Jeong; Park, Hoo Keun; Do, Young Rag; Min, Byoung Koun

2014-03-28

In this study we demonstrate the fabrication of CuInGaS₂ (CIGS) thin film solar cells with a three-dimensional (3D) nanostructure based on indium tin oxide (ITO) nanorod films and precursor solutions (Cu, In and Ga nitrates in alcohol). To obtain solution processed 3D nanostructured CIGS thin film solar cells, two different precursor solutions were applied to complete gap filling in ITO nanorods and achieve the desirable absorber film thickness. Specifically, a coating of precursor solution without polymer binder material was first applied to fill the gap between ITO nanorods followed by deposition of the second precursor solution in the presence of a binder to generate an absorber film thickness of ∼1.3 μm. A solar cell device with a (Al, Ni)/AZO/i-ZnO/CdS/CIGS/ITO nanorod/glass structure was constructed using the CIGS film, and the highest power conversion efficiency was measured to be ∼6.3% at standard irradiation conditions, which was 22.5% higher than the planar type of CIGS solar cell on ITO substrate fabricated using the same precursor solutions.

Mesoporous inverse opal TiO2 film as light scattering layer for dye-sensitized solar cell.

PubMed

Jin, Mingshi; Kim, Sung Soo; Yoon, Minyoung; Li, Zhenghua; Lee, Yoon Yun; Kim, Ji Man

2012-01-01

The light harvesting efficiency of dye-sensitized solar cells was enhanced by using a scattering layer. Such as sphere type TiO2, inverse photonic crystal TiO2, hollow spherical TiO2. Among these materials, the TiO2 with inverse photonic crystal (IPC) structure, synthesized by self-assembly using spherical templates, has attracted much attention due to their photonic crystal characteristics and light scattering effects. However, when applied in the DSSCs, the surface area of IPC is very low that caused insufficient adsorption amount of dye molecules. In the present work, a scattering layer with mesoporous inverse photonic crystal (MIPC) TiO2 film was fabricated by the sol-gel reactions with surfactant-assisted sol-gel method using poly(methyl methacrylate) as the template and titanium (IV) isopropoxide as the TiO2 precursor. After removing the PMMA and surfactant, a highly ordered macroporous structure with mesopores were successfully obtained. The surface area and total pore volume of the MIPC were 82 m2/g and 0.31 cm3/g, respectively, which is much larger than those of the IPC. The DSSCs with the scattering layer of MIPC film exhibited 18 and 10% higher photo-conversion efficiency than those of cells only with a nano-crystalline TiO2 film and with scattering layer of IPC film. From UV-visible spectra of dye solutions, the MIPC film showed a higher amount of absorbed dye molecules than those of the reference and IPC films. Accordingly, an increase in the photo-current density through abundant adsorption of the dye, coupled with inherent light scattering ability can improve overall photo-conversion efficiency.

Fabrication of High-Resolution Gamma-Ray Metallic Magnetic Calorimeters with Ag:Er Sensor and Thick Electroplated Absorbers

NASA Astrophysics Data System (ADS)

Hummatov, Ruslan; Hall, John A.; Kim, Geon-Bo; Friedrich, Stephan; Cantor, Robin; Boyd, S. T. P.

2018-05-01

We are developing metallic magnetic calorimeters for high-resolution gamma-ray spectroscopy for non-destructive assay of nuclear materials. Absorbers for these higher-energy photons can require substantial thickness to achieve adequate stopping power. We developed a new absorber fabrication process using dry-film photoresists to electroform cantilevered, thick absorbers. Gamma detectors with these absorbers have an energy resolution of 38 eV FWHM at 60 keV. In this report, we summarize modifications to STARCryo's "Delta 1000" process for our devices and describe the new absorber fabrication process.

Liftoff process for exfoliation of thin film photovoltaic devices and back contact formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haight, Richard A.; Hannon, James B.; Oida, Satoshi

A method for forming a back contact on an absorber layer in a photovoltaic device includes forming a two dimensional material on a first substrate. An absorber layer including Cu--Zn--Sn--S(Se) (CZTSSe) is grown over the first substrate on the two dimensional material. A buffer layer is grown on the absorber layer on a side opposite the two dimensional material. The absorber layer is exfoliated from the two dimensional material to remove the first substrate from a backside of the absorber layer opposite the buffer layer. A back contact is deposited on the absorber layer.

Modification of absorbent poly(glycerol-glutaric acid) films by the addition of monoglycerides

USDA-ARS?s Scientific Manuscript database

Monoglycerides (MGs) have been incorporated into the matrix of poly-(glycerol-co-glutaric acid) films to investigate their effect on the thermal, mechanical, and solvent absorption properties of the resultant films. MGs were concentrated using a combination of solvent extraction and molecular disti...

Photoelectronic Sensor with Gold Nanoparticle Plasmon Antenna

DTIC Science & Technology

2016-07-20

on glass substrate, GNP is absorbed on the film. After removing outer protein by UV ozone, TiO2 is deposited again and annealed. As optical... SiO2 Thin Films by CO2 Laser Annealing for Polycrystalline Silicon Thin Film Transistors”, AMD8-3L, The International Display Workshops Volume 21

Crosslinking of agarose bioplastic using citric acid.

PubMed

Awadhiya, Ankur; Kumar, David; Verma, Vivek

2016-10-20

We report chemical crosslinking of agarose bioplastic using citric acid. Crosslinking was confirmed using Fourier transform infrared (FTIR) spectroscopy. The effects of crosslinking on the tensile strength, swelling, thermal stability, and degradability of the bioplastic were studied in detail. The tensile strength of the bioplastic films increased from 25.1MPa for control films up to a maximum of 52.7MPa for citric acid crosslinked films. At 37°C, the amount of water absorbed by crosslinked agarose bioplastic was only 11.5% of the amount absorbed by non-crosslinked controls. Thermogravimetric results showed that the crosslinked samples retain greater mass at high temperature (>450°C) than control samples. Moreover, while the crosslinked films were completely degradable, the rate of degradation was lower compared to non-crosslinked controls. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dependence of lattice strain relaxation, absorbance, and sheet resistance on thickness in textured ZnO@B transparent conductive oxide for thin-film solar cell applications.

PubMed

Kou, Kuang-Yang; Huang, Yu-En; Chen, Chien-Hsun; Feng, Shih-Wei

2016-01-01

The interplay of surface texture, strain relaxation, absorbance, grain size, and sheet resistance in textured, boron-doped ZnO (ZnO@B), transparent conductive oxide (TCO) materials of different thicknesses used for thin film, solar cell applications is investigated. The residual strain induced by the lattice mismatch and the difference in the thermal expansion coefficient for thicker ZnO@B is relaxed, leading to an increased surface texture, stronger absorbance, larger grain size, and lower sheet resistance. These experimental results reveal the optical and material characteristics of the TCO layer, which could be useful for enhancing the performance of solar cells through an optimized TCO layer.

Thermal cycling and the optical and electrical characterization of self-assembled multilayer nile blue A-gold thin films.

PubMed

Geist, Brian; Spillman, William B; Claus, Richard O

2005-10-20

Some laser applications produce high power densities that can be dangerous to equipment and operators. We have fabricated thin-film coatings by using molecular electrostatic self-assembly to create a spectrally selective absorbing coating that is able to withstand thermal fluctuations from -20 degrees C to 120 degrees C. We made the thin-film coatings by alternating deposition of an organic dye and gold colloidal nanoparticles onto glass substrates. Nile Blue A perchlorate, with a maximum absorbance slightly above 632 nm, was chosen as the organic dye. Strong coupling between the dye molecules and the gold nanoparticles provides a redshift that increases as the film's thickness is increased. The incorporation of the gold colloidal nanoparticles also decreases the resistivity of the film. The resistivity of the film was measured with a four-point probe and found to be approximately 10 omega/cm for the two samples measured. Atomic-force microscopy was used to show that film thickness increased 2.4 nm per bilayer. The optical properties of the film were measured at the end of every 5 thermal cycles from -20 degrees C to 120 degrees C, and negligible degradation was observed after 30 cycles.

Photovoltaic enhancement due to surface-plasmon assisted visible-light absorption at the inartificial surface of lead zirconate-titanate film

NASA Astrophysics Data System (ADS)

Zheng, Fengang; Zhang, Peng; Wang, Xiaofeng; Huang, Wen; Zhang, Jinxing; Shen, Mingrong; Dong, Wen; Fang, Liang; Bai, Yongbin; Shen, Xiaoqing; Sun, Hua; Hao, Jianhua

2014-02-01

PZT film of 300 nm thickness was deposited on tin indium oxide (ITO) coated quartz by a sol-gel method. Four metal electrodes, such as Pt, Au, Cu and Ag, were used as top electrodes deposited on the same PZT film by sputtering at room temperature. In ITO-PZT-Ag and ITO-PZT-Au structures, the visible light (400-700 nm) can be absorbed partially by a PZT film, and the maximum efficiency of photoelectric conversion of the ITO-PZT-Ag structure was enhanced to 0.42% (100 mW cm-2, AM 1.5G), which is about 15 times higher than that of the ITO-PZT-Pt structure. Numerical simulations show that the natural random roughness of polycrystalline-PZT-metal interface can offer a possibility of coupling between the incident photons and SPs at the metal surface. The coincidence between the calculated SP properties and the measured EQE spectra reveals the SP origin of the photovoltaic enhancement in these ITO-PZT-metal structures, and the improved photocurrent output is caused by the enhanced optical absorption in the PZT region near the metal surface, rather than by the direct charge-transfer process between two materials.PZT film of 300 nm thickness was deposited on tin indium oxide (ITO) coated quartz by a sol-gel method. Four metal electrodes, such as Pt, Au, Cu and Ag, were used as top electrodes deposited on the same PZT film by sputtering at room temperature. In ITO-PZT-Ag and ITO-PZT-Au structures, the visible light (400-700 nm) can be absorbed partially by a PZT film, and the maximum efficiency of photoelectric conversion of the ITO-PZT-Ag structure was enhanced to 0.42% (100 mW cm-2, AM 1.5G), which is about 15 times higher than that of the ITO-PZT-Pt structure. Numerical simulations show that the natural random roughness of polycrystalline-PZT-metal interface can offer a possibility of coupling between the incident photons and SPs at the metal surface. The coincidence between the calculated SP properties and the measured EQE spectra reveals the SP origin of the photovoltaic enhancement in these ITO-PZT-metal structures, and the improved photocurrent output is caused by the enhanced optical absorption in the PZT region near the metal surface, rather than by the direct charge-transfer process between two materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05757g

Cu2ZnSnSe4 Thin Film Solar Cell with Depth Gradient Composition Prepared by Selenization of Sputtered Novel Precursors.

PubMed

Lai, Fang-I; Yang, Jui-Fu; Chen, Wei-Chun; Kuo, Shou-Yi

2017-11-22

In this study, we proposed a new method for the synthesis of the target material used in a two stage process for preparation of a high quality CZTSe thin film. The target material consisting of a mixture of Cu x Se and Zn x Sn 1-x alloy was synthesized, providing a quality CZTSe precursor layer for highly efficient CZTSe thin film solar cells. The CZTSe thin film can be obtained by annealing the precursor layers through a 30 min selenization process under a selenium atmosphere at 550 °C. The CZTSe thin films prepared by using the new precursor thin film were investigated and characterized using X-ray diffraction, Raman scattering, and photoluminescence spectroscopy. It was found that diffusion of Sn occurred and formed the CTSe phase and Cu x Se phase in the resultant CZTSe thin film. By selective area electron diffraction transmission electron microscopy images, the crystallinity of the CZTSe thin film was verified to be single crystal. By secondary ion mass spectroscopy measurements, it was confirmed that a double-gradient band gap profile across the CZTSe absorber layer was successfully achieved. The CZTSe solar cell with the CZTSe absorber layer consisting of the precursor stack exhibited a high efficiency of 5.46%, high short circuit current (J SC ) of 37.47 mA/cm 2 , open circuit voltage (V OC ) of 0.31 V, and fill factor (F.F.) of 47%, at a device area of 0.28 cm 2 . No crossover of the light and dark current-voltage (I-V) curves of the CZTSe solar cell was observed, and also, no red kink was observed under red light illumination, indicating a low defect concentration in the CZTSe absorber layer. Shunt leakage current with a characteristic metal/CZTSe/metal leakage current model was observed by temperature-dependent I-V curves, which led to the discovery of metal incursion through the CdS buffer layer on the CZTSe absorber layer. This leakage current, also known as space charge-limited current, grew larger as the measurement temperature increased and completely overwhelmed the diode current at a measurement temperature of 200 °C. This is due to interlayer diffusion of metal that increases the shunt leakage current and decreases the efficiency of the CZTSe thin film solar cells.

Physicochemically functional ultrathin films by interfacial polymerization

DOEpatents

Lonsdale, Harold K.; Babcock, Walter C.; Friensen, Dwayne T.; Smith, Kelly L.; Johnson, Bruce M.; Wamser, Carl C.

1990-01-01

Interfacially-polymerized ultrathin films containing physicochemically functional groups are disclosed, both with and without supports. Various applications are disclsoed, including membrane electrodes, selective membranes and sorbents, biocompatible materials, targeted drug delivery, and narrow band optical absorbers.

Thin film absorption characterization by focus error thermal lensing

NASA Astrophysics Data System (ADS)

Domené, Esteban A.; Schiltz, Drew; Patel, Dinesh; Day, Travis; Jankowska, E.; Martínez, Oscar E.; Rocca, Jorge J.; Menoni, Carmen S.

2017-12-01

A simple, highly sensitive technique for measuring absorbed power in thin film dielectrics based on thermal lensing is demonstrated. Absorption of an amplitude modulated or pulsed incident pump beam by a thin film acts as a heat source that induces thermal lensing in the substrate. A second continuous wave collimated probe beam defocuses after passing through the sample. Determination of absorption is achieved by quantifying the change of the probe beam profile at the focal plane using a four-quadrant detector and cylindrical lenses to generate a focus error signal. This signal is inherently insensitive to deflection, which removes noise contribution from point beam stability. A linear dependence of the focus error signal on the absorbed power is shown for a dynamic range of over 105. This technique was used to measure absorption loss in dielectric thin films deposited on fused silica substrates. In pulsed configuration, a single shot sensitivity of about 20 ppm is demonstrated, providing a unique technique for the characterization of moving targets as found in thin film growth instrumentation.

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagul, Sagar B., E-mail: nano.sbbagul@gmail.com; Upadhye, Deepak S.; Sharma, Ramphal, E-mail: rps.phy@gmail.com

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology ofmore » Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.« less

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

NASA Astrophysics Data System (ADS)

Bagul, Sagar B.; Upadhye, Deepak S.; Sharma, Ramphal

2016-05-01

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology of Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.

Optical properties and surface topography of CdCl2 activated CdTe thin films

NASA Astrophysics Data System (ADS)

Patel, S. L.; Purohit, A.; Chander, S.; Dhaka, M. S.

2018-05-01

The effect of post-CdCl2 heat treatment on optical properties and surface topography of evaporated CdTe thin films is investigated. The pristine and thermally annealed films were subjected to UV-Vis spectrophotometer and atomic force microscopy (AFM) to investigate the optical properties and surface topography, respectively. The absorbance is found to be maximum (˜90%) at 320°C temperature and transmittance found to be minimum and almost constant in ultraviolet and visible regions. The direct band gap is increased from 1.42 eV to 2.12 eV with post-CdCl2 annealing temperature. The surface topography revealed that the uniformity is improved with annealing temperature and average surface roughness is found in the range of 83.3-144.3 nm as well as grains have cylindrical hill-like shapes. The investigated results indicate that the post-CdCl2 treated films annealed at 320°C may be well-suitable for thin film solar cells as an absorber layer.

X-Ray Detection Visits the Classroom

ERIC Educational Resources Information Center

Peralta, Luis; Farinha, Ana; Pinto, Ana

2008-01-01

Film has been used to detect x-rays since the early days of their discovery by Rontgen. Although nowadays superseded by other techniques, film still provides a cheap means of x-ray detection, making it attractive in high-school or undergraduate university courses. If some sort of quantitative result is required, the film's optical absorbance or…

Interference-enhanced infrared-to-visible upconversion in solid-state thin films sensitized by colloidal nanocrystals

NASA Astrophysics Data System (ADS)

Wu, Mengfei; Jean, Joel; Bulović, Vladimir; Baldo, Marc A.

2017-05-01

Infrared-to-visible photon upconversion has potential applications in photovoltaics, sensing, and bioimaging. We demonstrate a solid-state thin-film device that utilizes sensitized triplet-triplet exciton annihilation, converting infrared photons absorbed by colloidal lead sulfide nanocrystals (NCs) into visible photons emitted from a luminescent dopant in rubrene at low incident light intensities. A typical bilayer device consisting of a monolayer of NCs and a doped film of rubrene is limited by low infrared absorption in the thin NC film. Here, we augment the bilayer with an optical spacer layer and a silver-film back reflector, resulting in interference effects that enhance the optical field and thus the absorption in the NC film. The interference-enhanced device shows an order-of-magnitude increase in the upconverted emission at the wavelength of λ = 610 nm when excited at λ = 980 nm. At incident light intensities above 1.1 W/cm2, the device attains maximum efficiency, converting (1.6 ± 0.2)% of absorbed infrared photons into higher-energy singlet excitons in rubrene.

Effect of flash lamp annealing on electrical activation in boron-implanted polycrystalline Si thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Do, Woori; Jin, Won-Beom; Choi, Jungwan

2014-10-15

Highlights: • Intensified visible light irradiation was generated via a high-powered Xe arc lamp. • The disordered Si atomic structure absorbs the intensified visible light. • The rapid heating activates electrically boron-implanted Si thin films. • Flash lamp heating is applicable to low temperature polycrystalline Si thin films. - Abstract: Boron-implanted polycrystalline Si thin films on glass substrates were subjected to a short duration (1 ms) of intense visible light irradiation generated via a high-powered Xe arc lamp. The disordered Si atomic structure absorbs the intense visible light resulting from flash lamp annealing. The subsequent rapid heating results in themore » electrical activation of boron-implanted Si thin films, which is empirically observed using Hall measurements. The electrical activation is verified by the observed increase in the crystalline component of the Si structures resulting in higher transmittance. The feasibility of flash lamp annealing has also been demonstrated via a theoretical thermal prediction, indicating that the flash lamp annealing is applicable to low-temperature polycrystalline Si thin films.« less

Preparation of nonconducting infrared-absorbing thin films

NASA Astrophysics Data System (ADS)

Gradhand, Martin; Breitenstein, Otwin

2005-05-01

A simple procedure for preparing colloidal "black" bismuth films is introduced, which leaves the target cold and does not pollute the recipient. The Bi evaporation occurs in a closed box in the evaporation chamber with an internal radiation shield. The bismuth is evaporated from a tantalum boat at a residual air pressure of 2×102Pa. The resulting films with a thickness of about 10μm are structureless down to a spatial resolution of 5.6μm, they become electrically insulating after 48h storage time in air, and they show an IR absorbance of above 70% in the 3-5μm wavelength range. The films are easily removable in an ultrasonic water bath. Thus, these films are ideally appropriate to increase the IR emissivity of microelectronic structures in microthermal infrared failure analysis investigations such as lock-in thermography, as is demonstrated in an application example. The application of this film may improve the thermographic detection limit of heat sources below metallized areas by up to a factor of 10, leading to a saving in acquisition time by a factor of 100.

Conduction band position tuning and Ga-doping in (Cd,Zn)S alloy thin films

DOE PAGES

Baranowski, Lauryn L.; Christensen, Steven; Welch, Adam W.; ...

2017-02-13

In recent years, the number of novel photovoltaic absorber materials under exploration has rapidly increased. However, to reap the most benefit from these new absorbers, alternative device structures and components must also be considered. In particular, the choice of a heterojunction partner, or contact layer, is critical to device optimization. In this work, we explore alternative n-type contact layer candidates that could be widely applicable to a variety of new absorbers. We use theory to calculate the band edge tuning provided by a variety of II-VI alloy systems, and select the (Cd,Zn)S system as one that affords a wide rangemore » of conduction band tuning. The synthesis of (Cd,Zn)S alloys is explored using atomic layer deposition, which afforded precise compositional control and produced crystalline thin films. The predicted tuning of the band gap and conduction band minimum is confirmed through X-ray photoelectron spectroscopy and optical absorption measurements. In addition, we investigated Ga-doping in Cd 0.6Zn 0.4S films to decrease their series resistance when used as contact layers in photovoltaic devices. In conclusion, this study provides a framework for exploring and optimizing alternative contact layer materials, which will prove critical to the success of new PV absorbers.« less

Photochemical stability of UV-screening transparent acrylic copolymers of 2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole

NASA Technical Reports Server (NTRS)

Gupta, A.; Scott, G. W.; Kliger, D.; Vogl, O.

1983-01-01

The mechanism of photodegradation of certain hydroxyphenyl benzotriazole based ultraviolet absorbers has been investigated and a new polymerizable ultraviolet absorber in this group has been synthesized. The photoreactivity is entirely confined at the surface of polymethylmethacrylate films containing the ultraviolet absorbers as pendant groups. A mechanism involving sensitized photooxidation has been proposed to interpret the data.

Physicochemically functional ultrathin films by interfacial polymerization

DOEpatents

Lonsdale, H.K.; Babcock, W.C.; Friensen, D.T.; Smith, K.L.; Johnson, B.M.; Wamser, C.C.

1990-08-14

Interfacially-polymerized ultrathin films containing physicochemically functional groups are disclosed, both with and without supports. Various applications are disclosed, including membrane electrodes, selective membranes and sorbents, biocompatible materials, targeted drug delivery, and narrow band optical absorbers. 3 figs.

Characterizing the discoloration of EBT3 films in solar UV A+B measurement using red LED

NASA Astrophysics Data System (ADS)

Omar, Ahmad Fairuz; Osman, Ummi Shuhada; Tan, Kok Chooi

2017-09-01

This research article proposes an alternative method to measure the discoloration or the color changes of EBT3 films due to exposure by solar ultraviolet (UV A+B) dose. Common methods to measure the color changes of EBT3 are through imaging technique measured by flatbed scanner and through absorbance spectroscopy measured by visible spectrometer. The research presented in this article measure the color changes of EBT3 through simplified optical system using the combination of light emitting diode (LED) as the light source and photodiode as the detector. In this research, 50 pieces of Gafchromic EBT3 films were prepared with the dimension of 3 cm x 2 cm. Color of the films changed from light green to dark green based on the total accumulated UV dose (mJ/cm2) by each film that depends on the duration of exposure, irradiance level (mW/cm2) and condition of the sky. The exposed films were then taken to the laboratory for its color measurement using absorbance spectroscopy technique and using newly developed simplified optical instrument using LED-photodiode. Results from spectroscopy technique indicate that wavelength within red region exhibit better response in term of linearity and responsivity towards the colors of EBT3 films. Wavelength of 626 nm was then selected as the peak emission wavelength for LED-photodiode absorbance system. UV dose measurement using LEDphotodiode system produced good result with coefficient of determination, R2 of 0.97 and root mean square of error, RMSE of 431.82 mJ/cm2 while comparatively, similar wavelength but analyzed from spectroscopy dataset produced R2 of 0.988 and RMSE of 268.94 mJ/cm2.

Annealing Effects on Structure and Optical Properties of Diamond-Like Carbon Films Containing Silver.

PubMed

Meškinis, Šarūnas; Čiegis, Arvydas; Vasiliauskas, Andrius; Šlapikas, Kęstutis; Gudaitis, Rimantas; Yaremchuk, Iryna; Fitio, Volodymyr; Bobitski, Yaroslav; Tamulevičius, Sigitas

2016-12-01

In the present study, diamond-like carbon films with embedded Ag nanoparticles (DLC:Ag) were deposited by reactive magnetron sputtering. Structure of the films was investigated by Raman scattering spectroscopy. Atomic force microscopy was used to define thickness of DLC:Ag films as well as to study the surface morphology and size distribution of Ag nanoparticles. Optical absorbance and reflectance spectra of the films were studied in the 180-1100-nm range. Air annealing effects on structure and optical properties of the DLC:Ag were investigated. Annealing temperatures were varied in the 180-400 °C range. Changes of size and shape of the Ag nanoclusters took place due to agglomeration. It was found that air annealing of DLC:Ag films can result in graphitization following destruction of the DLC matrix. Additional activation of surface-enhanced Raman scattering (SERS) effect in DLC:Ag films can be achieved by properly selecting annealing conditions. Annealing resulted in blueshift as well as significant narrowing of the plasmonic absorbance and reflectance peaks. Moreover, quadrupole surface plasmon resonance peaks appeared. Modeling of absorption spectra of the nanoclusters depending on the shape and surrounding media has been carried out.

Using high haze (> 90%) light-trapping film to enhance the efficiency of a-Si:H solar cells

NASA Astrophysics Data System (ADS)

Chu, Wei-Ping; Lin, Jian-Shian; Lin, Tien-Chai; Tsai, Yu-Sheng; Kuo, Chen-Wei; Chung, Ming-Hua; Hsieh, Tsung-Eong; Liu, Lung-Chang; Juang, Fuh-Shyang; Chen, Nien-Po

2012-07-01

The high haze light-trapping (LT) film offers enhanced scattering of light and is applied to a-Si:H solar cells. UV glue was spin coated on glass, and then the LT pattern was imprinted. Finally, a UV lamp was used to cure the UV glue on the glass. The LT film effectively increased the Haze ratio of glass and decreased the reflectance of a-Si:H solar cells. Therefore, the photon path length was increased to obtain maximum absorption by the absorber layer. High Haze LT film is able to enhance short circuit current density and efficiency of the device, as partial composite film generates broader scattering light, thereby causing shorter wave length light to be absorbed by the P layer so that the short circuit current density decreases. In case of lab-made a-Si:H thin film solar cells with v-shaped LT films, superior optoelectronic performances have been found (Voc = 0.74 V, Jsc = 15.62 mA/cm2, F.F. = 70%, and η = 8.09%). We observed ~ 35% enhancement of the short-circuit current density and ~ 31% enhancement of the conversion efficiency.

Annealing Effects on Structure and Optical Properties of Diamond-Like Carbon Films Containing Silver

NASA Astrophysics Data System (ADS)

Meškinis, Šarūnas; Čiegis, Arvydas; Vasiliauskas, Andrius; Šlapikas, Kęstutis; Gudaitis, Rimantas; Yaremchuk, Iryna; Fitio, Volodymyr; Bobitski, Yaroslav; Tamulevičius, Sigitas

2016-03-01

In the present study, diamond-like carbon films with embedded Ag nanoparticles (DLC:Ag) were deposited by reactive magnetron sputtering. Structure of the films was investigated by Raman scattering spectroscopy. Atomic force microscopy was used to define thickness of DLC:Ag films as well as to study the surface morphology and size distribution of Ag nanoparticles. Optical absorbance and reflectance spectra of the films were studied in the 180-1100-nm range. Air annealing effects on structure and optical properties of the DLC:Ag were investigated. Annealing temperatures were varied in the 180-400 °C range. Changes of size and shape of the Ag nanoclusters took place due to agglomeration. It was found that air annealing of DLC:Ag films can result in graphitization following destruction of the DLC matrix. Additional activation of surface-enhanced Raman scattering (SERS) effect in DLC:Ag films can be achieved by properly selecting annealing conditions. Annealing resulted in blueshift as well as significant narrowing of the plasmonic absorbance and reflectance peaks. Moreover, quadrupole surface plasmon resonance peaks appeared. Modeling of absorption spectra of the nanoclusters depending on the shape and surrounding media has been carried out.

Topological, chemical and electro-optical characteristics of riboflavin-doped artificial and natural DNA thin films

NASA Astrophysics Data System (ADS)

Gnapareddy, Bramaramba; Dugasani, Sreekantha Reddy; Son, Junyoung; Park, Sung Ha

2018-02-01

DNA is considered as a useful building bio-material, and it serves as an efficient template to align functionalized nanomaterials. Riboflavin (RF)-doped synthetic double-crossover DNA (DX-DNA) lattices and natural salmon DNA (SDNA) thin films were constructed using substrate-assisted growth and drop-casting methods, respectively, and their topological, chemical and electro-optical characteristics were evaluated. The critical doping concentrations of RF ([RF]C, approx. 5 mM) at given concentrations of DX-DNA and SDNA were obtained by observing the phase transition (from crystalline to amorphous structures) of DX-DNA and precipitation of SDNA in solution above [RF]C. [RF]C are verified by analysing the atomic force microscopy images for DX-DNA and current, absorbance and photoluminescence (PL) for SDNA. We study the physical characteristics of RF-embedded SDNA thin films, using the Fourier transform infrared spectrum to understand the interaction between the RF and DNA molecules, current to evaluate the conductance, absorption to understand the RF binding to the DNA and PL to analyse the energy transfer between the RF and DNA. The current and UV absorption band of SDNA thin films decrease up to [RF]C followed by an increase above [RF]C. By contrast, the PL intensity illustrates the reverse trend, as compared to the current and UV absorption behaviour as a function of the varying [RF]. Owing to the intense PL characteristic of RF, the DNA lattices and thin films with RF might offer immense potential to develop efficient bio-sensors and useful bio-photonic devices.

Topological, chemical and electro-optical characteristics of riboflavin-doped artificial and natural DNA thin films

PubMed Central

Gnapareddy, Bramaramba; Son, Junyoung

2018-01-01

DNA is considered as a useful building bio-material, and it serves as an efficient template to align functionalized nanomaterials. Riboflavin (RF)-doped synthetic double-crossover DNA (DX-DNA) lattices and natural salmon DNA (SDNA) thin films were constructed using substrate-assisted growth and drop-casting methods, respectively, and their topological, chemical and electro-optical characteristics were evaluated. The critical doping concentrations of RF ([RF]C, approx. 5 mM) at given concentrations of DX-DNA and SDNA were obtained by observing the phase transition (from crystalline to amorphous structures) of DX-DNA and precipitation of SDNA in solution above [RF]C. [RF]C are verified by analysing the atomic force microscopy images for DX-DNA and current, absorbance and photoluminescence (PL) for SDNA. We study the physical characteristics of RF-embedded SDNA thin films, using the Fourier transform infrared spectrum to understand the interaction between the RF and DNA molecules, current to evaluate the conductance, absorption to understand the RF binding to the DNA and PL to analyse the energy transfer between the RF and DNA. The current and UV absorption band of SDNA thin films decrease up to [RF]C followed by an increase above [RF]C. By contrast, the PL intensity illustrates the reverse trend, as compared to the current and UV absorption behaviour as a function of the varying [RF]. Owing to the intense PL characteristic of RF, the DNA lattices and thin films with RF might offer immense potential to develop efficient bio-sensors and useful bio-photonic devices. PMID:29515837

Low-Cost, Efficient, and Durable H2 Production by Photoelectrochemical Water Splitting with CuGa3Se5 Photocathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muzzillo, Christopher; Klein, Walter E; Li, Zhen

Photoelectrochemical (PEC) water splitting is an elegant method of converting sunlight and water into H2 fuel. To be commercially advantageous, PEC devices must become cheaper, more efficient, and much more durable. This work examines low-cost polycrystalline chalcopyrite films, which are successful as photovoltaic absorbers, for application as PEC absorbers. In particular, Cu-Ga-Se films with wide band gaps can be employed as top cell photocathodes in tandem devices as a realistic route to high efficiencies. In this report, we demonstrate that decreasing Cu/Ga composition from 0.66 to 0.31 in Cu-Ga-Se films increased the band gap from 1.67 to 1.86 eV andmore » decreased saturated photocurrent density from 18 to 8 mA/cm2 as measured by chopped-light current-voltage (CLIV) measurements in a 0.5 M sulfuric acid electrolyte. Buffer and catalyst surface treatments were not applied to the Cu-Ga-Se films, and they exhibited promising stability, evidenced by unchanged CLIV after 9 months of storage in air. Finally, films with Cu/Ga = 0.36 (approximately stoichiometric CuGa3Se5) and 1.86 eV band gaps had exceptional durability and continuously split water for 17 days (~12 mA/cm2 at -1 V vs RHE). This is equivalent to ~17 200 C/cm2, which is a world record for any polycrystalline PEC absorber. These results indicate that CuGa3Se5 films are prime candidates for cheaply achieving efficient and durable PEC water splitting.« less

Low-Cost, Efficient, and Durable H2 Production by Photoelectrochemical Water Splitting with CuGa3Se5 Photocathodes.

PubMed

Muzzillo, Christopher P; Klein, W Ellis; Li, Zhen; DeAngelis, Alexander Daniel; Horsley, Kimberly; Zhu, Kai; Gaillard, Nicolas

2018-06-13

Photoelectrochemical (PEC) water splitting is an elegant method of converting sunlight and water into H 2 fuel. To be commercially advantageous, PEC devices must become cheaper, more efficient, and much more durable. This work examines low-cost polycrystalline chalcopyrite films, which are successful as photovoltaic absorbers, for application as PEC absorbers. In particular, Cu-Ga-Se films with wide band gaps can be employed as top cell photocathodes in tandem devices as a realistic route to high efficiencies. In this report, we demonstrate that decreasing Cu/Ga composition from 0.66 to 0.31 in Cu-Ga-Se films increased the band gap from 1.67 to 1.86 eV and decreased saturated photocurrent density from 18 to 8 mA/cm 2 as measured by chopped-light current-voltage (CLIV) measurements in a 0.5 M sulfuric acid electrolyte. Buffer and catalyst surface treatments were not applied to the Cu-Ga-Se films, and they exhibited promising stability, evidenced by unchanged CLIV after 9 months of storage in air. Finally, films with Cu/Ga = 0.36 (approximately stoichiometric CuGa 3 Se 5 ) and 1.86 eV band gaps had exceptional durability and continuously split water for 17 days (∼12 mA/cm 2 at -1 V vs RHE). This is equivalent to ∼17 200 C/cm 2 , which is a world record for any polycrystalline PEC absorber. These results indicate that CuGa 3 Se 5 films are prime candidates for cheaply achieving efficient and durable PEC water splitting.

Revealing the nature of morphological changes in carbon nanotube-polymer saturable absorber under high-power laser irradiation.

PubMed

Chernysheva, Maria; Araimi, Mohammed Al; Rance, Graham A; Weston, Nicola J; Shi, Baogui; Saied, Sayah; Sullivan, John L; Marsh, Nicholas; Rozhin, Aleksey

2018-05-10

Composites of single-walled carbon nanotubes (SWNTs) and water-soluble polymers (WSP) are the focus of significant worldwide research due to a number of applications in biotechnology and photonics, particularly for ultrashort pulse generation. Despite the unique possibility of constructing non-linear optical SWNT-WSP composites with controlled optical properties, their thermal degradation threshold and limit of operational power remain unexplored. In this study, we discover the nature of the SWNT-polyvinyl alcohol (PVA) film thermal degradation and evaluate the modification of the composite properties under continuous high-power ultrashort pulse laser operation. Using high-precision optical microscopy and micro-Raman spectroscopy, we have examined SWNT-PVA films before and after continuous laser radiation exposure (up to 40 hours) with a maximum optical fluence of 2.3 mJ·cm -2 . We demonstrate that high-intensity laser radiation results in measurable changes in the composition and morphology of the SWNT-PVA film due to efficient heat transfer from SWNTs to the polymer matrix. The saturable absorber modification does not affect the laser operational performance. We anticipate our work to be a starting point for more sophisticated research aimed at the enhancement of SWNT-PVA films fabrication for their operation as reliable saturable absorbers in high-power ultrafast lasers.

Concentrating light in Cu(In,Ga)Se2 solar cells

NASA Astrophysics Data System (ADS)

Schmid, Martina; Yin, Guanchao; Song, Min; Duan, Shengkai; Heidmann, Berit; Sancho-Martinez, Diego; Kämmer, Steven; Köhler, Tristan; Manley, Phillip; Lux-Steiner, Martha Ch.

2017-01-01

Light concentration has proven beneficial for solar cells, most notably for highly efficient but expensive absorber materials using high concentrations and large scale optics. Here, we investigate the light concentration for cost-efficient thin-film solar cells that show nano- or microtextured absorbers. Our absorber material of choice is Cu(In,Ga)Se2 (CIGSe), which has a proven stabilized record efficiency of 22.6% and which-despite being a polycrystalline thin-film material-is very tolerant to environmental influences. Taking a nanoscale approach, we concentrate light in the CIGSe absorber layer by integrating photonic nanostructures made from dielectric materials. The dielectric nanostructures give rise to resonant modes and field localization in their vicinity. Thus, when inserted inside or adjacent to the absorber layer, absorption and efficiency enhancement are observed. In contrast to this internal absorption enhancement, external enhancement is exploited in the microscaled approach: mm-sized lenses can be used to concentrate light onto CIGSe solar cells with lateral dimensions reduced down to the micrometer range. These micro solar cells come with the benefit of improved heat dissipation compared with the large scale concentrators and promise compact high-efficiency devices. Both approaches of light concentration allow for reduction in material consumption by restricting the absorber dimension either vertically (ultrathin absorbers for dielectric nanostructures) or horizontally (microabsorbers for concentrating lenses) and have significant potential for efficiency enhancement.

The feasibility of using methylene blue sensitized polyvinylalcohol film as a linear polarizer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jyothilakshmi, K.; Anju, K. S.; Arathy, K.

2014-01-28

Linear light polarizing films selectively transmit radiations vibrating along an electromagnetic radiation vector and selectively absorb radiations vibrating along a second electromagnetic radiation vector. It happens according to the anisotropy of the film . In the present study the polarization effects of methylene blue sensitized polyvinyl alcohol is investigated. The polarization effects on the dye concentration, heating and stretching of film also are evaluated.

How Does a SILAR CdSe Film Grow? Tuning the Deposition Steps to Suppress Interfacial Charge Recombination in Solar Cells.

PubMed

Becker, Matthew A; Radich, James G; Bunker, Bruce A; Kamat, Prashant V

2014-05-01

Successive ionic layer adsorption and reaction (SILAR) is a popular method of depositing the metal chalcogenide semiconductor layer on the mesoscopic metal oxide films for designing quantum-dot-sensitized solar cells (QDSSCs) or extremely thin absorber (ETA) solar cells. While this deposition method exhibits higher loading of the light-absorbing semiconductor layer than direct adsorption of presynthesized colloidal quantum dots, the chemical identity of these nanostructures and the evolution of interfacial structure are poorly understood. We have now analyzed step-by-step SILAR deposition of CdSe films on mesoscopic TiO2 nanoparticle films using X-ray absorption near-edge structure analysis and probed the interfacial structure of these films. The film characteristics interestingly show dependence on the order in which the Cd and Se are deposited, and the CdSe-TiO2 interface is affected only during the first few cycles of deposition. Development of a SeO2 passivation layer in the SILAR-prepared films to form a TiO2/SeO2/CdSe junction facilitates an increase in photocurrents and power conversion efficiencies of quantum dot solar cells when these films are integrated as photoanodes in a photoelectrochemical solar cell.

Structural and optical properties of tin disulphide thin films grown by flash evaporation

NASA Astrophysics Data System (ADS)

Banotra, Arun; Padha, Naresh

2018-04-01

Tin Disulphide thin films were deposited by Flash Evaporation method on corning Glass Substrate at different substrate temperatures. The deposited films were undertaken for Structural, Optical and compositional characterizations. Compositional analysis of the films exhibited decrease in the sulphur content enabling S/Sn ratio to vary from 2.05 to 1.32 with increasing substrate temperature. X-ray diffraction reveals amorphous nature of the as-deposited films with varying substrate temperatures. Optical measurements estimated from absorbance spectra suggest higher absorbance at λ≤500nm and higher transmission at λ≥500nm with bandgap changes from 2.45eV to 2.09eV. The 323K as-deposited films were undertaken for annealing which transforms the films into crystalline form corresponding to hexagonal SnS2 phase at 423K and above. However, the optical response for the annealed samples shows a higher transmission of 70% in the visible region which increases further in the Infrared region of the spectrum achieving maximum transmission upto 98%. This higher transmission in the Visible to Infrared region of the solar spectrum in amorphous as well as crystalline form makes the film suitable for their use as a window layer in the Solar Cell Design.

Enhancement of the Ultraviolet Photoresponsivity of Al-doped ZnO Thin Films Prepared by using the Sol-gel Spin-coating Method

NASA Astrophysics Data System (ADS)

Lee, Wookbin; Leem, Jae-Young

2018-03-01

We report the structural, morphological, optical, and ultraviolet (UV) photoresponse properties of Al-doped ZnO (AZO) thin films prepared on silicon substrates with different Al doping concentrations by using the sol-gel spin-coating method. An analysis of the X-ray diffraction patterns of the AZO thin films revealed that the average grain size decreased and the c-axis lattice constant increased with Al content. The field-emission scanning electron microscopy images showed that with Al doping, the grain size decreased, but the film density increased with increasing Al doping concentration from 0% to 3%. These results indicate that the surface area of the film increased with increasing Al doping. The absorbance spectra revealed that the UV absorbance of the AZO thin films increased with increasing Al doping concentration and that the absorption onset shifted towards lower energies. The photoluminescence spectra revealed that with increasing Al doping, the intensity of the visible emission greatly decreased and the visible emission peak shifted forward lower energy (a red shift). The UV sensor based on the AZO thin films exhibited a higher responsivity than that based on the undoped ZnO thin film. Therefore, this study provides a facile method for improving the photoresponsivity of UV sensors.

Novel Solution Process for Fabricating Ultra-Thin-Film Absorber Layers in Fe 2SiS 4 and Fe 2GeS 4 Photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orefuwa, Samuel A.; Lai, Cheng-Yu; Dobson, Kevin D.

2014-05-12

Fe 2SiS 4 and Fe 2GeS 4 crystalline materials posses direct bandgaps of ~1.55 and ~1.4 eV respectively and an absorption coefficient larger than 10^5 cm–1; their theoretical potential as solar photovoltaic absorbers has been demonstrated. However, no solar devices that employ either Fe 2SiS 4 or Fe 2GeS 4 have been reported to date. In the presented work, nanoprecursors to Fe 2SiS 4 and Fe 2GeS 4 have been fabricated and employed to build ultra-thin-film layers via spray coating and rod coating methods. Temperature-dependent X-Ray diffraction analyses of nanoprecursors coatings show an unprecedented low temperature for forming crystalline Femore » 2SiS 4 and Fe 2GeS 4. Fabricating of ultra-thin-film photovoltaic devices utilizing Fe 2SiS 4 and Fe 2GeS 4 as solar absorber material is presented.« less

The effect of water uptake on the mechanical properties of low-k organosilicate glass

NASA Astrophysics Data System (ADS)

Guo, X.; Jakes, J. E.; Nichols, M. T.; Banna, S.; Nishi, Y.; Shohet, J. L.

2013-08-01

Water uptake in porous low-k dielectrics has become a significant challenge for both back-end-of-line integration and circuit reliability. The influence of absorbed water on the mechanical properties of plasma-enhanced chemical-vapor-deposited organosilicate glasses (SiCOH) was investigated with nanoindentation. The roles of physisorbed (α-bonded) and chemisorbed (β-bonded) water were examined separately through annealing at different temperatures. Nanoindentation measurements were performed on dehydrated organosilicate glass during exposure to varying humidity conditions. The elastic modulus and hardness for as-deposited SiCOH are intimately linked to the nature and concentration of the absorbed water in the dielectric. Under mild-annealing conditions, the water-related film mechanical property changes were shown to be reversible. The mechanical properties of UV-cured SiCOH were also shown to depend on absorbed water, but to a lesser extent because UV curing depopulates the hydrophilic chemical groups in SiCOH. High-load indentation tests showed that in-diffusion of water in the film/substrate interface can degrade the hardness of SiCOH/Si film stacks significantly, while not significantly changing the elastic modulus.

Organic-inorganic nano-composite films for photonic applications made by multi-beam multi-target pulsed laser deposition with remote control of the plume directions

NASA Astrophysics Data System (ADS)

Darwish, Abdalla M.; Moore, Shaelynn; Mohammed, Aziz; Alexander, Deonte'; Bastian, Tyler; Dorlus, Wydglif; Sarkisov, Sergey S.; Patel, Darayas N.; Mele, Paolo; Koplitz, Brent

2016-09-01

There has been an explosive interest in the technique of laser assisted deposition of polymer nano-composite films exploiting the matrix assisted pulsed laser evaporation (MAPLE) with regard to the polymer host as can be judged form recent publications.1-4 In MAPLE, a frozen solution of a polymer in a relatively volatile solvent is used as a laser target. The solvent and concentration are selected so that first, the polymer of interest can dissolve to form a dilute, particulate free solution, second, the majority of the laser energy is initially absorbed by the solvent molecules and not by the solute molecules, and third, there is no photochemical reaction between the solvent and the solute. The light-material interaction in MAPLE can be described as a photothermal process. The photon energy absorbed by the solvent is converted to thermal energy that causes the polymer to be heated but the solvent to vaporize. As the surface solvent molecules are evaporated into the gas phase, polymer molecules are exposed at the gas-target matrix interface. The polymer molecules attain sufficient kinetic energy through collective collisions with the evaporating solvent molecules, to be transferred into the gas phase. By careful optimization of the MAPLE deposition conditions (laser wavelength, repetition rate, solvent type, concentration, temperature, and background gas and gas pressure), this process can occur without any significant polymer decomposition. The MAPLE process proceeds layer-by-layer, depleting the target of solvent and polymer in the same concentration as the starting matrix. When a substrate is positioned directly in the path of the plume, a coating starts to form from the evaporated polymer molecules, while the volatile solvent molecules are evacuated by the pump from the deposition chamber. In case of fabrication of polymer nanocomposites, MAPLE targets are usually prepared as nano-colloids of the additives of interest in the initial polymer solutions. Mixing the components of different nature, organic polymers and inorganic dopants, in the same target at a certain proportion and exposing them to the same laser beam not necessarily brings good quality nano-composite films. The laser pulse energy and wavelength cannot be optimized for each component individually. Also, the mixing proportion in the composite film is dictated by the initial proportion of the target and thus cannot be changed in the process. These limitations were removed in the recently proposed method of multi-beam and multi-target deposition (in its doublebeam/ dual-target variation) using a MAPLE polymer target and one inorganic target, each being concurrently exposed to laser beams of different wavelengths.5-14 Using the method, nano-composite films of polymer poly(methyl methacrylate) known as PMMA doped with a rare earth (RE) inorganic upconversion phosphor compounds were prepared. Also, a nano-composite film of thermoelectric film of inorganic aluminum-doped ZnO known as AZO was impregnated with PMMA nano-fillers with the purpose of improving electrical conductivity and thermoelectric performance.10, 14 The polymer target was a frozen (to a temperature of liquid nitrogen) PMMA solution in chlorobenzene exposed to a 1064- nm laser beam from a Q-switched Nd:YAG pulsed laser. The inorganic targets were the pellets made of the compressed micro-powders of highly efficient RE-doped NaYF4 or the sintered powder of AZO concurrently ablated with the

Chlorine and sulfur determination in extra-heavy crude oil by inductively coupled plasma optical emission spectrometry after microwave-induced combustion

NASA Astrophysics Data System (ADS)

Pereira, Juliana S. F.; Mello, Paola A.; Moraes, Diogo P.; Duarte, Fábio A.; Dressler, Valderi L.; Knapp, Guenter; Flores, Érico M. M.

2009-06-01

In this study, microwave-induced combustion (MIC) of extra-heavy crude oil is proposed for further chlorine and sulfur determination by inductively coupled plasma optical emission spectrometry (ICP OES). Combustion was carried out under oxygen pressure (20 bar) in quartz vessels using ammonium nitrate (50 µl of 6 mol l - 1 solution) as ignition aid. Samples were wrapped with polyethylene film and placed on a quartz holder positioned inside the quartz vessels. The need for an additional reflux step after combustion and the type and concentration of absorbing solution (water, 0.02 to 0.9 mmol l - 1 H 2O 2, 10 to 100 mmol l - 1 (NH 4) 2CO 3 or 0.1 to 14 mol l - 1 HNO 3) were studied. The influence of sample mass, O 2 pressure and maximum pressure attained during the combustion process were investigated. Recoveries from 92 to 102% were obtained for Cl and S for all absorbing solutions. For comparison, Cl and S determination was also performed by ion chromatography (IC) using 25 mmol l - 1 (NH 4) 2CO 3 as absorbing solution. Using MIC with a reflux step the agreement was better than 95% for certified reference materials of similar composition (crude oil, petroleum coke, coal and residual fuel oil). Microwave-assisted digestion and water extraction in high pressure closed vessels were also evaluated. Using these procedures the maximum recoveries were 30 and 98% for Cl and S, respectively, using microwave-assisted digestion and 70% for Cl and less than 1% for S by water extraction procedure. Limits of detection by ICP OES were 12 and 5 µg g - 1 for Cl and S, respectively, and the corresponding values by IC were 1.2 and 8 µg g - 1 . Using MIC it was possible to digest simultaneously up to eight samples resulting in a solution suitable for the determination of both analytes with a single combustion step.

Progress with polycrystalline silicon thin-film solar cells on glass at UNSW

NASA Astrophysics Data System (ADS)

Aberle, Armin G.

2006-01-01

Polycrystalline Si (pc-Si) thin-film solar cells on glass have long been considered a very promising approach for lowering the cost of photovoltaic (PV) solar electricity. In recent years there have been dramatic advances with this PV technology, and the first commercial modules (CSG Solar) are expected to hit the marketplace in 2006. The CSG modules are based on solid-phase crystallisation of plasma-enhanced chemical vapor deposition (PECVD) -deposited amorphous Si. Independent research in the author's group at the University of New South Wales (UNSW) during recent years has led to the development of three alternative pc-Si thin-film solar cells on glass—EVA, ALICIA and ALICE. Cell thickness is generally about 2 μm. The first two cells are made by vacuum evaporation, whereas ALICE cells can be made by either vacuum evaporation or PECVD. Evaporation has the advantage of being a fast and inexpensive Si deposition method. A crucial component of ALICIA and ALICE cells is a seed layer made on glass by metal-induced crystallisation of amorphous silicon (a-Si). The absorber layer of these cells is made by either ion-assisted Si epitaxy (ALICIA) or solid-phase epitaxy of a-Si (ALICE). This paper reports on the status of these three new thin-film PV technologies. All three solar cells seem to be capable of voltages of over 500 mV and, owing to their potentially inexpensive and scalable fabrication process, have significant industrial appeal.

Precise Composition Tailoring of Mixed-Cation Hybrid Perovskites for Efficient Solar Cells by Mixture Design Methods.

PubMed

Li, Liang; Liu, Na; Xu, Ziqi; Chen, Qi; Wang, Xindong; Zhou, Huanping

2017-09-26

Mixed anion/cation perovskites absorber has been recently implemented to construct highly efficient single junction solar cells and tandem devices. However, considerable efforts are still required to map the composition-property relationship of the mixed perovskites absorber, which is essential to facilitate device design. Here we report the intensive exploration of mixed-cation perovskites in their compositional space with the assistance of a rational mixture design (MD) methods. Different from the previous linear search of the cation ratios, it is found that by employing the MD methods, the ternary composition can be tuned simultaneously following simplex lattice designs or simplex-centroid designs, which enable significantly reduced experiment/sampling size to unveil the composition-property relationship for mixed perovskite materials and to boost the resultant device efficiency. We illustrated the composition-property relationship of the mixed perovskites in multidimension and achieved an optimized power conversion efficiency of 20.99% in the corresponding device. Moreover, the method is demonstrated to be feasible to help adjust the bandgap through rational materials design, which can be further extended to other materials systems, not limited in polycrystalline perovskites films for photovoltaic applications only.

Depth-Profiling Electronic and Structural Properties of Cu(In,Ga)(S,Se)2 Thin-Film Solar Cell.

PubMed

Chiang, Ching-Yu; Hsiao, Sheng-Wei; Wu, Pin-Jiun; Yang, Chu-Shou; Chen, Chia-Hao; Chou, Wu-Ching

2016-09-14

Utilizing a scanning photoelectron microscope (SPEM) and grazing-incidence X-ray powder diffraction (GIXRD), we studied the electronic band structure and the crystalline properties of the pentanary Cu(In,Ga)(S,Se)2 (CIGSSe) thin-film solar cell as a function of sample depth on measuring the thickness-gradient sample. A novel approach is proposed for studying the depth-dependent information on thin films, which can provide a gradient thickness and a wide cross-section of the sample by polishing process. The results exhibit that the CIGSSe absorber layer possesses four distinct stoichiometries. The growth mechanism of this distinctive compositional distribution formed by a two-stage process is described according to the thermodynamic reaction and the manufacturing process. On the basis of the depth-profiling results, the gradient profiles of the conduction and valence bands were constructed to elucidate the performance of the electrical properties (in this case, Voc = 620 mV, Jsc = 34.6 mA/cm(2), and η = 14.04%); the valence-band maxima (VBM) measured with a SPEM in the spectroscopic mode coincide with this band-structure model, except for a lowering of the VBM observed in the surface region of the absorber layer due to the ordered defect compound (ODC). In addition, the depth-dependent texturing X-ray diffraction pattern presents the crystalline quality and the residual stress for each depth of a thin-film device. We find that the randomly oriented grains in the bottom region of the absorber layer and the different residual stress between the underlying Mo and the absorber interface, which can deteriorate the electrical performance due to peeling-off effect. An anion interstitial defect can be observed on comparing the anion concentration of the elemental distribution with crystalline composition; a few excess sulfur atoms insert in interstitial sites at the front side of the absorber layer, whereas the interstitial selenium atoms insert at the back side.

Shadow-angle method for anisotropic and weakly absorbing films.

PubMed

Surdutovich, G; Vitlina, R; Baranauskas, V

1999-07-01

A method for determining the optical properties of a film on an isotropic substrate is proposed. The method is based on the existence of two specific incidence angles in the angular interference pattern of the p-polarized light where oscillations of the reflection coefficient cease. The first of these angles, theta(B1), is the well-known Abelès angle, i.e., the ambient-film Brewster angle, and the second angle theta(B2) is the film-substrate Brewster angle. In the conventional planar geometry and in a vacuum ambient there is a rigorous constraint epsilon(1) + epsilon > epsilon(1)epsilon on the film and the substrate dielectric permittivities epsilon(1) and epsilon, respectively, for the existence of the second angle theta(B2.) The limitation may be removed in an experiment by use of a cylindrical lens as an ambient with epsilon(0) > 1, so that both angles become observable. This, contrary to general belief, allows one to adopt the conventional Abelès method not only for films with epsilon(1) close to the substrate's value epsilon but also for any value of epsilon(1). The method, when applied to a wedge-shaped film or to any film of unknown variable thickness, permits one to determine (i) the refractive index of a film on an unknown substrate, (ii) the vertical and the horizontal optical anisotropies of a film on an isotropic substrate, (iii) the weak absorption of a moderately thick film on a transparent or an absorbing isotropic substrate.

Evidence for Cu2-xSe platelets at grain boundaries and within grains in Cu(In,Ga)Se2 thin films

NASA Astrophysics Data System (ADS)

Simsek Sanli, E.; Ramasse, Q. M.; Mainz, R.; Weber, A.; Abou-Ras, D.; Sigle, W.; van Aken, P. A.

2017-07-01

Cu(In,Ga)Se2 (CIGS)-based solar cells reach high power-conversion efficiencies of above 22%. In this work, a three-stage co-evaporation method was used for their fabrication. During the growth stages, the stoichiometry of the absorbers changes from Cu-poor ([Cu]/([In] + [Ga]) < 1) to Cu-rich ([Cu]/([In] + [Ga]) > 1) and finally becomes Cu-poor again when the growth process is completed. It is known that, according to the Cu-In-Ga-Se phase diagram, a Cu-rich growth leads to the presence of Cu2-xSe (x = 0-0.25), which is assumed to assist in recrystallization, grain growth, and defect annihilation in the CIGS layer. So far, Cu2-xSe precipitates with spatial extensions on the order of 10-100 nm have been detected only in Cu-rich CIGS layers. In the present work, we report Cu2-xSe platelets with widths of only a few atomic planes at grain boundaries and as inclusions within grains in a polycrystalline, Cu-poor CIGS layer, as evidenced by high-resolution scanning transmission electron microscopy (STEM). The chemistry of the Cu-Se secondary phase was analyzed by electron energy-loss spectroscopy, and STEM image simulation confirmed the identification of the detected phase. These results represent additional experimental evidence for the proposed topotactical growth model for Cu-Se-assisted CIGS thin-film formation under Cu-rich conditions.

Direct observation of back energy transfer in blue phosphorescent materials for organic light emitting diodes by time-resolved optical waveguide spectroscopy.

PubMed

Hirayama, H; Sugawara, Y; Miyashita, Y; Mitsuishi, M; Miyashita, T

2013-02-25

We demonstrate a high-sensitive transient absorption technique for detection of excited states in an organic thin film by time-resolved optical waveguide spectroscopy. By using a laser beam as a probe light, we detect small change in the transient absorbance which is equivalent to 10 -7 absorbance unit in a conventional method. This technique was applied to organic thin films of blue phosphorescent materials for organic light emitting diodes. We directly observed the back energy transfer from emitting guest molecules to conductive host molecules.

Development of a real-time reflectance and transmittance monitoring system for the manufacturing of metaldielectric light absorbers

NASA Astrophysics Data System (ADS)

Badoil, Bruno; Cathelinaud, Michel; Lemarchand, Fabien; Lemarquis, Frédéric; Lequime, Michel

2017-11-01

Metal-dielectric light absorbers are of great interest for suppressing stray light in optical systems. Such coatings can give an absorption level greater than 99.9% over a broad spectral range provided that the complex refractive index of metallic films is accurately known. For this purpose we developed a new real-time monitoring system that allows to measure in situ both reflectance and transmittance of the coating during manufacturing in the deposition chamber. This paper describes the system design and its characteristics and gives some preliminary results concerning metallic thin film characterizations.

Mechanically Robust, Stretchable Solar Absorbers with Submicron-Thick Multilayer Sheets for Wearable and Energy Applications.

PubMed

Lee, Hye Jin; Jung, Dae-Han; Kil, Tae-Hyeon; Kim, Sang Hyeon; Lee, Ki-Suk; Baek, Seung-Hyub; Choi, Won Jun; Baik, Jeong Min

2017-05-31

A facile method to fabricate a mechanically robust, stretchable solar absorber for stretchable heat generation and an enhanced thermoelectric generator (TEG) is demonstrated. This strategy is very simple: it uses a multilayer film made of titanium and magnesium fluoride optimized by a two-dimensional finite element frequency-domain simulation, followed by the application of mechanical stresses such as bending and stretching to the film. This process produces many microsized sheets with submicron thickness (∼500 nm), showing great adhesion to any substrates such as fabrics and polydimethylsiloxane. It exhibits a quite high light absorption of approximately 85% over a wavelength range of 0.2-4.0 μm. Under 1 sun illumination, the solar absorber on various stretchable substrates increased the substrate temperature to approximately 60 °C, irrespective of various mechanical stresses such as bending, stretching, rubbing, and even washing. The TEG with the absorber on the top surface also showed an enhanced output power of 60%, compared with that without the absorber. With an incident solar radiation flux of 38.3 kW/m 2 , the output power significantly increased to 24 mW/cm 2 because of the increase in the surface temperature to 141 °C.

Laser post-processing of halide perovskites for enhanced photoluminescence and absorbance

NASA Astrophysics Data System (ADS)

Tiguntseva, E. Y.; Saraeva, I. N.; Kudryashov, S. I.; Ushakova, E. V.; Komissarenko, F. E.; Ishteev, A. R.; Tsypkin, A. N.; Haroldson, R.; Milichko, V. A.; Zuev, D. A.; Makarov, S. V.; Zakhidov, A. A.

2017-11-01

Hybrid halide perovskites have emerged as one of the most promising type of materials for thin-film photovoltaic and light-emitting devices. Further boosting their performance is critically important for commercialization. Here we use femtosecond laser for post-processing of organo-metalic perovskite (MAPbI3) films. The high throughput laser approaches include both ablative silicon nanoparticles integration and laser-induced annealing. By using these techniques, we achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally 10-fold enhancement of absorbance in a perovskite layer with the silicon nanoparticles. Direct laser annealing allows for increasing of photoluminescence over 130%, and increase absorbance over 300% in near-IR range. We believe that the developed approaches pave the way to novel scalable and highly effective designs of perovskite based devices.

The preparation and characterization of optical thin films produced by ion-assisted deposition

NASA Astrophysics Data System (ADS)

Martin, P. J.; Netterfield, R. P.; Sainty, W. G.; Pacey, C. G.

1984-06-01

Ion-based deposition techniques have been successfully used to deposit compound films suitable for photothermal applications, as well as dielectric films with stable and reproducible optical properties. Thus, thin films of TiN, a-Si:H, and PbS have been obtained by ion-assisted deposition for photothermal solar-selective elements and similarly prepared dielectric layers of ZrO2, SiO2, and Al2O3 have been used as protective coatings on Ag and Al mirrors. It is shown that the technique of ion-assisted deposition affords control over the film density, microstructure, adhesion, composition, and optical properties. Details of the process and film properties are discussed.

[Absorbed doses to critical organs from full mouth dental radiography].

PubMed

Zhang, G; Yasuhiko, O; Hidegiko, Y

1999-01-01

A few studies were reported in China on radiological risk of dental radiography. The aim of this study is to evaluate the absorbed doses of patients from the full mouth radiographs, and to find out the contribution from each projection to the total absorbed dose of the organs. Absorbed doses to critical organs were measured from 14-film complete dental radiography. The organs included pituitary, optical lens, parotid glands, submandibular glands, sublingual glands, thyroid, breasts, ovary, testes and the skin in center field of each projection were studied. A-radiation analog dosimetry system (RANDO) phantom with thermoluminescent dosimeters (ILD200) was used for the study. All of the exposure parameters were fixed. The total filtration was 2 mm Al equivalent. The column collaboration was 6 cm in diameter and 20 cm in length. The absorbed doses of organs were measured three times in each projection of the full-mouth series (FMS) exposures. The absorbed dose of lenses in FMS (249 microGy) in present study was much less (10%) than the doses (2,630 microGy) reported in 1976. The doses absorbed of other organs in the present study were thyroid gland (125 microGy), pituitary gland (112 microGy), parotid gland (153 microGy), submandibular gland (629 microGy), sublingual gland (1,900 microGy), and breast gland (12 microGy). The doses of the ovary and testis were to small to further analysis. All of the results show that the radiation risk to patients in intraoral radiograph has been reduced significantly. In the pituitary, half of the dose is from both sides of the maxillary molar projection. For the lenses, the largest contribultions of radiation (60%) come from the ipsilateral molar and premolar projection of maxilla. In parotid gland, up to 57% of the dose is from the contralateral molar, pre-molar and canine of maxilla. It could be derived that about 90% of the absorbed doses could be avoided in FMS if the column collimator is 20 cm long and the filter is 2.0 mm thick. If we use the 10-film complete mouth radiograph instead of the 14-film series, more 20% of the doses would be reduced.

Fabrication of bright and thin Zn₂SiO₄ luminescent film for electron beam excitation-assisted optical microscope.

PubMed

Furukawa, Taichi; Kanamori, Satoshi; Fukuta, Masahiro; Nawa, Yasunori; Kominami, Hiroko; Nakanishi, Yoichiro; Sugita, Atsushi; Inami, Wataru; Kawata, Yoshimasa

2015-07-13

We fabricated a bright and thin Zn₂SiO₄ luminescent film to serve as a nanometric light source for high-spatial-resolution optical microscopy based on electron beam excitation. The Zn₂SiO₄ luminescent thin film was fabricated by annealing a ZnO film on a Si₃N₄ substrate at 1000 °C in N₂. The annealed film emitted bright cathodoluminescence compared with the as-deposited film. The film is promising for nano-imaging with electron beam excitation-assisted optical microscopy. We evaluated the spatial resolution of a microscope developed using this Zn₂SiO₄ luminescent thin film. This is the first report of the investigation and application of ZnO/Si₃N₄ annealed at a high temperature (1000 °C). The fabricated Zn₂SiO₄ film is expected to enable high-frame-rate dynamic observation with ultra-high resolution using our electron beam excitation-assisted optical microscopy.

Interpenetrating polymer network ion exchange membranes and method for preparing same

DOEpatents

Alexandratos, Spiro D.; Danesi, Pier R.; Horwitz, E. Philip

1989-01-01

Interpenetrating polymer network ion exchange membranes include a microporous polymeric support film interpenetrated by an ion exchange polymer and are produced by absorbing and polymerizing monomers within the support film. The ion exchange polymer provides ion exchange ligands at the surface of and throughout the support film which have sufficient ligand mobility to extract and transport ions across the membrane.

X Ray Mask Of Gold-Carbon Mixture Absorber On BCN Compound Substrate Fabricated By Plasma Processes

NASA Astrophysics Data System (ADS)

Aiyer, Chandrasekhar R.; Itoh, Satoshi; Yamada, Hitomi; Morita, Shinzo; Hattori, Shuzo

1988-06-01

X-ray mask fabrication based on BCN compound membrane and gold containing polymeric carbon ( Au-C ) absorber by totally dry processes is proposed. The Au-C films were depo-sited by plasma polymerization of propylene or styrene monomers and co-evaporation of gold. These films have 2 to 5 times higher etching rate than that of pure gold for 09 RIE, depending on the Au content. The stress in the films could be reduced to 1.9 E 7 N/m2 by annealing. The BCN films were deposited on silicon wafers by rf (13.56 MHz) plasma CVD with diborane, methane and nitrogen as source gases at typical deposition rate of 30 nm/min. The optical (633nm) and X ray (Pd L~) transparencies were nearly 80% for film thickness of 6 um. Patterning of Au-C was achieved by using tungsten as intermediate layer and PMMA electron beam resist. CF4 RIE was used to etch the tungsten layer which in turn acted as mask for the gold carbide 02 RIE. The process parameters and the characteristics of the Au-C and BCN films are presented.

Growth of Cu2ZnSnS4(CZTS) by Pulsed Laser Deposition for Thin film Photovoltaic Absorber Material

NASA Astrophysics Data System (ADS)

Nandur, Abhishek; White, Bruce

2014-03-01

CZTS (Cu2ZnSnS4) has become the subject of intense interest because it is an ideal candidate absorber material for thin-film solar cells with an optimal band gap (1.5 eV), high absorption coefficient (104 cm-1) and abundant elemental components. Pulsed Laser Deposition (PLD) provides excellent control over film composition since thin films are deposited under high vacuum with excellent stoichiometry transfer from the target. CZTS thin films were deposited using PLD from a stoichiometrically close CZTS target (Cu2.6Zn1.1Sn0.7S3.44). The effects of laser energy fluence and substrate temperature and post-deposition sulfur annealing on the surface morphology, composition and optical absorption have been investigated. Optimal CZTS thin films exhibited a band gap of 1.54 eV with an absorption coefficient of 4x104cm-1. A solar cell utilizing PLD grown CZTS with the structure SLG/Mo/CZTS/CdS/ZnO/ITO showed a conversion efficiency of 5.85% with Voc = 376 mV, Jsc = 38.9 mA/cm2 and Fill Factor, FF = 0.40.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, X. L.; Meng, Q. X.; Yuan, C. X.

The visible light broadband perfect absorbers based on the silver (Ag) nano elliptical disks and holes array are studied using finite difference time domain simulations. The semiconducting indium silicon dioxide thin film is introduced as the space layer in this sandwiched structure. Utilizing the asymmetrical geometry of the structures, polarization sensitivity for transverse electric wave (TE)/transverse magnetic wave (TM) and left circular polarization wave (LCP)/right circular polarization wave (RCP) of the broadband absorption are gained. The absorbers with Ag nano disks and holes array show several peaks absorbance of 100% by numerical simulation. These simple and flexible perfect absorbers aremore » particularly desirable for various potential applications including the solar energy absorber.« less

Radiolysis products and sensory properties of electron-beam-irradiated high-barrier food-packaging films containing a buried layer of recycled low-density polyethylene.

PubMed

Chytiri, S D; Badeka, A V; Riganakos, K A; Kontominas, M G

2010-04-01

The aim was to study the effect of electron-beam irradiation on the production of radiolysis products and sensory changes in experimental high-barrier packaging films composed of polyamide (PA), ethylene-vinyl alcohol (EVOH) and low-density polyethylene (LDPE). Films contained a middle buried layer of recycled LDPE, while films containing 100% virgin LDPE as the middle buried layer were taken as controls. Irradiation doses ranged between zero and 60 kGy. Generally, a large number of radiolysis products were produced during electron-beam irradiation, even at the lower absorbed doses of 5 and 10 kGy (approved doses for food 'cold pasteurization'). The quantity of radiolysis products increased with irradiation dose. There were no significant differences in radiolysis products identified between samples containing a recycled layer of LDPE and those containing virgin LDPE (all absorbed doses), indicating the 'functional barrier' properties of external virgin polymer layers. Sensory properties (mainly taste) of potable water were affected after contact with irradiated as low as 5 kGy packaging films. This effect increased with increasing irradiation dose.

SU-E-T-163: Thin-Film Organic Photocell (OPV) Properties in MV and KV Beams for Dosimetry Applications.

PubMed

Ng, S K; Hesser, J; Zhang, H; Gowrisanker, S; Yakushevich, S; Shulhevich, Y; Abkai, C; Wack, L; Zygmanski, P

2012-06-01

To characterize dosimetric properties of low-cost thin film organic-based photovoltaic (OPV) cells to kV and MV x-ray beams for their usage as large area dosimeter for QA and patient safety monitoring device. A series of thin film OPV cells of various areas and thicknesses were irradiated with MV beams to evaluate the stability and reproducibility of their response, linearity and sensitivity to absorbed dose. The OPV response to x-rays of various linac energies were also characterized. Furthermore the practical (clinical) sensitivity of the cells was determined using IMRT sweeping gap test generated with various gap sizes. To evaluate their potential usage in the development of low cost kV imaging device, the OPV cells were irradiated with kV beam (60-120 kVp) from a fluoroscopy unit. Photocell response to the absorbed dose was characterized as a function of the organic thin film thickness and size, beam energy and exposure for kV beams as well. In addition, photocell response was determined with and without thin plastic scintillator. Response of the OPV cells to the absorbed dose from kV and MV beams are stable and reproducible. The photocell response was linearly proportional to the size and about slightly decreasing with the thickness of the organic thin film, which agrees with the general performance of the photocells in visible light. The photocell response increases as a linear function of absorbed dose and x-ray energy. The sweeping gap tests performed showed that OPV cells have sufficient practical sensitivity to measured MV x-ray delivery with gap size as small as 1 mm. With proper calibration, the OPV cells could be used for online radiation dose measurement for quality assurance and patient safety purposes. Their response to kV beam show promising potential in development of low cost kV radiation detection devices. © 2012 American Association of Physicists in Medicine.

Controlled electrodeposition of Cu-Ga from a deep eutectic solvent for low cost fabrication of CuGaSe2 thin film solar cells.

PubMed

Steichen, Marc; Thomassey, Matthieu; Siebentritt, Susanne; Dale, Phillip J

2011-03-14

The electrochemical deposition of Ga and Cu-Ga alloys from the deep eutectic solvent choline chloride/urea (Reline) is investigated to prepare CuGaSe(2) (CGS) semiconductors for their use in thin film solar cells. Ga electrodeposition is difficult from aqueous solution due to its low standard potential and the interfering hydrogen evolution reaction (HER). Ionic liquid electrolytes offer a better thermal stability and larger potential window and thus eliminate the interference of solvent breakdown reactions during Ga deposition. We demonstrate that metallic Ga can be electrodeposited from Reline without HER interference with high plating efficiency on Mo and Cu electrodes. A new low cost synthetic route for the preparation of CuGaSe(2) absorber thin films is presented and involves the one-step electrodeposition of Cu-Ga precursors from Reline followed by thermal annealing. Rotating disk electrode (RDE) cyclic voltammetry (CV) is used in combination with viscosity measurements to determine the diffusion coefficients of gallium and copper ions in Reline. The composition of the codeposited Cu-Ga precursor layers can be controlled to form Cu/Ga thin films with precise stoichiometry, which is important for achieving good optoelectronic properties of the final CuGaSe(2) absorbers. The morphology, the chemical composition and the crystal structure of the deposited thin films are analysed by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD). Annealing of the Cu-Ga films in a selenium atmosphere allowed the formation of high quality CuGaSe(2) absorber layers. Completed CGS solar cells achieved a 4.1% total area power conversion efficiency.

Electrical properties and surface morphology of electron beam evaporated p-type silicon thin films on polyethylene terephthalate for solar cells applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ang, P. C.; Ibrahim, K.; Pakhuruddin, M. Z.

2015-04-24

One way to realize low-cost thin film silicon (Si) solar cells fabrication is by depositing the films with high-deposition rate and manufacturing-compatible electron beam (e-beam) evaporation onto inexpensive foreign substrates such as glass or plastic. Most of the ongoing research is reported on e-beam evaporation of Si films on glass substrates to make polycrystalline solar cells but works combining both e-beam evaporation and plastic substrates are still scarce in the literature. This paper studies electrical properties and surface morphology of 1 µm electron beam evaporated Al-doped p-type silicon thin films on textured polyethylene terephthalate (PET) substrate for application as anmore » absorber layer in solar cells. In this work, Si thin films with different doping concentrations (including an undoped reference) are prepared by e-beam evaporation. Energy dispersion X-ray (EDX) showed that the Si films are uniformly doped by Al dopant atoms. With increased Al/Si ratio, doping concentration increased while both resistivity and carrier mobility of the films showed opposite relationships. Root mean square (RMS) surface roughness increased. Overall, the Al-doped Si film with Al/Si ratio of 2% (doping concentration = 1.57×10{sup 16} atoms/cm{sup 3}) has been found to provide the optimum properties of a p-type absorber layer for fabrication of thin film Si solar cells on PET substrate.« less

Effect of thickness on physical properties of electron beam vacuum evaporated CdZnTe thin films for tandem solar cells

NASA Astrophysics Data System (ADS)

Chander, Subhash; Dhaka, M. S.

2016-10-01

The thickness and physical properties of electron beam vacuum evaporated CdZnTe thin films have been optimized in the present work. The films of thickness 300 nm and 400 nm were deposited on ITO coated glass substrates and subjected to different characterization tools like X-ray diffraction (XRD), UV-Vis spectrophotometer, source meter and scanning electron microscopy (SEM) to investigate the structural, optical, electrical and surface morphological properties respectively. The XRD results show that the as-deposited CdZnTe thin films have zinc blende cubic structure and polycrystalline in nature with preferred orientation (111). Different structural parameters are also evaluated and discussed. The optical study reveals that the optical transition is found to be direct and energy band gap is decreased for higher thickness. The transmittance is found to increase with thickness and red shift observed which is suitable for CdZnTe films as an absorber layer in tandem solar cells. The current-voltage characteristics of deposited films show linear behavior in both forward and reverse directions as well as the conductivity is increased for higher film thickness. The SEM studies show that the as-deposited CdZnTe thin films are found to be homogeneous, uniform, small circle-shaped grains and free from crystal defects. The experimental results confirm that the film thickness plays an important role to optimize the physical properties of CdZnTe thin films for tandem solar cell applications as an absorber layer.

Absorption-induced scattering and surface plasmon out-coupling from absorber-coated plasmonic metasurfaces

PubMed Central

Petoukhoff, Christopher E.; O'Carroll, Deirdre M.

2015-01-01

Interactions between absorbers and plasmonic metasurfaces can give rise to unique optical properties not present for either of the individual materials and can influence the performance of a host of optical sensing and thin-film optoelectronic applications. Here we identify three distinct mode types of absorber-coated plasmonic metasurfaces: localized and propagating surface plasmons and a previously unidentified optical mode type called absorption-induced scattering. The extinction of the latter mode type can be tuned by controlling the morphology of the absorber coating and the spectral overlap of the absorber with the plasmonic modes. Furthermore, we show that surface plasmons are backscattered when the crystallinity of the absorber is low but are absorbed for more crystalline absorber coatings. This work furthers our understanding of light–matter interactions between absorbers and surface plasmons to enable practical optoelectronic applications of metasurfaces. PMID:26271900

Mechanical behaviour of metallic thin films on polymeric substrates and the effect of ion beam assistance on crack propagation

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, M.; Coupeau, C.; Colin, J.

2005-01-10

The mechanisms of crack propagation in metallic films on polymeric substrates have been studied through in situ atomic force microscopy observations of thin films under tensile stresses and finite element stress calculations. Two series of films - ones deposited with ion beam assistance, the others without - have been investigated. The observations and stress calculations show that ion beam assistance can change drastically the propagation of cracks in coated materials: by improving the adhesion film/substrate, it slows down the delamination process, but in the same time enhances the cracks growth in the thickness of the material.

Optical Properties of Al-Doped ZnO Films in the Infrared Region and Their Absorption Applications

NASA Astrophysics Data System (ADS)

Zheng, Hua; Zhang, Rong-Jun; Li, Da-Hai; Chen, Xin; Wang, Song-You; Zheng, Yu-Xiang; Li, Meng-Jiao; Hu, Zhi-Gao; Dai, Ning; Chen, Liang-Yao

2018-05-01

The optical properties of aluminum-doped zinc oxide (AZO) thin films were calculated rapidly and accurately by point-by-point analysis from spectroscopic ellipsometry (SE) data. It was demonstrated that there were two different physical mechanisms, i.e., the interfacial effect and crystallinity, for the thickness-dependent permittivity in the visible and infrared regions. In addition, there was a blue shift for the effective plasma frequency of AZO when the thickness increased, and the effective plasma frequency did not exist for AZO ultrathin films (< 25 nm) in the infrared region, which demonstrated that AZO ultrathin films could not be used as a negative index metamaterial. Based on detailed permittivity research, we designed a near-perfect absorber at 2-5 μm by etching AZO-ZnO alternative layers. The alternative layers matched the phase of reflected light, and the void cylinder arrays extended the high absorption range. Moreover, the AZO absorber demonstrated feasibility and applicability on different substrates.

Atmospheric Pressure Spray Chemical Vapor Deposited CuInS2 Thin Films for Photovoltaic Applications

NASA Technical Reports Server (NTRS)

Harris, J. D.; Raffaelle, R. P.; Banger, K. K.; Smith, M. A.; Scheiman, D. A.; Hepp, A. F.

2002-01-01

Solar cells have been prepared using atmospheric pressure spray chemical vapor deposited CuInS2 absorbers. The CuInS2 films were deposited at 390 C using the single source precursor (PPh3)2CuIn(SEt)4 in an argon atmosphere. The absorber ranges in thickness from 0.75 - 1.0 micrometers, and exhibits a crystallographic gradient, with the leading edge having a (220) preferred orientation and the trailing edge having a (112) orientation. Schottky diodes prepared by thermal evaporation of aluminum contacts on to the CuInS2 yielded diodes for films that were annealed at 600 C. Solar cells were prepared using annealed films and had the (top down) composition of Al/ZnO/CdS/CuInS2/Mo/Glass. The Jsc, Voc, FF and (eta) were 6.46 mA per square centimeter, 307 mV, 24% and 0.35%, respectively for the best small area cells under simulated AM0 illumination.

Monitoring of Diisopropyl Fluorophosphate Hydrolysis by Fluoride-Selective Polymeric Films Using Absorbance Spectroscopy

PubMed Central

Ramanathan, Madhumati; Wang, Lin; Wild, James R.; Meyeroff, Mark E.; Simonian, Aleksandr L.

2012-01-01

In this study, a novel system for the detection and quantification of organofluorophosphonates (OFP) has been developed by using an optical sensing polymeric membrane to detect the fluoride ions produced upon OFP hydrolysis. Diisopropyl fluorophosphate (DFP), a structural analogue of Type G Chemical Warfare Agents such as Sarin (GB) and Soman (GD), is used as the surrogate target analyte. An optical sensing fluoride-ion-selective polymeric film was formulated from plasticized PVC containing aluminum(III) octaethylporphyrin and ETH 7075 chromoionophore (Al[OEP]-ETH 7075). Selected formulations were used to detect the fluoride ions produced by the catalytic hydrolysis of DFP by the enzyme organophosphate hydrolase (OPH, EC 3.1.8.1). The changes in absorbance that corresponded to the deprotonated state of chromoionophore within the film results from simultaneous co-extraction of fluoride and protons as DFP hydrolysis takes place in the solution phase in contact with the film. The developed sensing system demonstrates excellent sensitivity for concentrations as low as 0.1 µM DFP. PMID:20441875

Fast Resistive Bolometry

NASA Astrophysics Data System (ADS)

Graham, Jeffrey

2005-10-01

A bolometer with microsecond scale response time is under construction for the Caltech spheromak experiment to measure radiation from a ˜20 μs duration plasma discharge emitting ˜10^2---10^3 kW/m^2. A gold film several micrometers thick absorbs the radiation, heats up, and the consequent change in resistance can be measured. The film itself is vacuum deposited upon a glass slide. Several geometries for the film are under consideration to optimize the amount of radiation absorbed, the response time and the signal-to-noise ratio. We measure the change in voltage across the film for a known current driven through it; a square pulse (3---30A, ˜20 μs) is used to avoid Joule heating. Results from prototypes tested with a UV flashlamp will be presented. After optimizing the bolometer design, the final vacuum-compatible diagnostic would consist of a plasma-facing bolometer and a reference in a camera obscura. This device could provide a design for fast resistive bolometry.

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer

PubMed Central

Zhang, Zhaojing; Yao, Liyong; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming‐Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2017-01-01

Abstract Double layer distribution exists in Cu2SnZnSe4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double‐layer distribution of CZTSe film is eliminated entirely and the formation of MoSe2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSex mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu‐Sn‐Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu2Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm2 and a CZTSe solar cell with efficiency of 7.2% is fabricated. PMID:29610727

Demonstration of surface plasmons in metal island films and the effect of the surrounding medium--An undergraduate experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orfanides, P.; Buckner, T. F.; Buncick, M. C.

2000-10-01

We present a demonstration of the surface plasmon phenomenon as it occurs in thin metal island films. The metal films are deposited on glass microscope slides. The effect of the surface plasmon resonance may be observed visually on the slide without further apparatus. Heating the film changes the shape of the islands and therefore the resonant frequency of the surface plasmon and changes the color of the film. Placing the film in a dielectric medium changes the resonance condition for the surface plasmon again and changes the color again. We show this by coating the slides with commercially available liquidsmore » with different indices of refraction. We present a theoretical model that assumes the islands are oblate spheroids. There are enough details given so that the equations can be programed and the theoretical optical absorbance can be reproduced. We also present a modification to the theory so that the shift in resonant frequency can be calculated when the spheroids are immersed in the index fluids. We describe our apparatus for making thin films and our optical spectrometer system. We then present optical absorbance measurements of thin films of both Ag and Au in air and in two liquids with different indices of refraction. (c) 2000 American Association of Physics Teachers.« less

Modified Back Contact Interface of CZTSe Thin Film Solar Cells: Elimination of Double Layer Distribution in Absorber Layer.

PubMed

Zhang, Zhaojing; Yao, Liyong; Zhang, Yi; Ao, Jianping; Bi, Jinlian; Gao, Shoushuai; Gao, Qing; Jeng, Ming-Jer; Sun, Guozhong; Zhou, Zhiqiang; He, Qing; Sun, Yun

2018-02-01

Double layer distribution exists in Cu 2 SnZnSe 4 (CZTSe) thin films prepared by selenizing the metallic precursors, which will degrade the back contact of Mo substrate to absorber layer and thus suppressing the performance of solar cell. In this work, the double-layer distribution of CZTSe film is eliminated entirely and the formation of MoSe 2 interfacial layer is inhibited successfully. CZTSe film is prepared by selenizing the precursor deposited by electrodeposition method under Se and SnSe x mixed atmosphere. It is found that the insufficient reaction between ZnSe and Cu-Sn-Se phases in the bottom of the film is the reason why the double layer distribution of CZTSe film is formed. By increasing Sn content in the metallic precursor, thus making up the loss of Sn because of the decomposition of CZTSe and facilitate the diffusion of liquid Cu 2 Se, the double layer distribution is eliminated entirely. The crystallization of the formed thin film is dense and the grains go through the entire film without voids. And there is no obvious MoSe 2 layer formed between CZTSe and Mo. As a consequence, the series resistance of the solar cell reduces significantly to 0.14 Ω cm 2 and a CZTSe solar cell with efficiency of 7.2% is fabricated.

Design of a five-band terahertz perfect metamaterial absorber using two resonators

NASA Astrophysics Data System (ADS)

Meng, Tianhua; Hu, Dan; Zhu, Qiaofen

2018-05-01

We present a polarization-insensitive five-band terahertz perfect metamaterial absorber composed of two metallic circular rings and a metallic ground film separated by a dielectric layer. The calculated results show that the absorber has five distinctive absorption bands whose peaks are greater than 99% on average. The physical origin of the absorber originates from the combination of dipolar, hexapolar, and surface plasmon resonance of the patterned metallic structure, which is different from the work mechanism of previously reported absorbers. In addition, the influence of the structural parameters on the absorption spectra is analyzed to further confirm the origin of the five-band absorption peaks. The proposed absorber has potential applications in terahertz imaging, refractive index sensing, and material detecting.

Bandgap Engineering of Cu(In 1-xGax)Se 2 Absorber Layers Fabricated using CuInSe 2 and CuGaSe 2 Targets for One-Step Sputtering Process

DOE PAGES

Park, Jae -Cheol; Lee, Jeon -Ryang; Al-Jassim, Mowafak; ...

2016-10-17

Here we have demonstrated that the bandgap of Cu(In 1-xGa x)Se 2(CIGS) absorber layers was readily controlled by using a one-step sputtering process. CIGS thin-film sample libraries with different Ga/(In + Ga) ratios were synthesized on soda-lime glass at 550 °C using a combinatorial magnetron sputtering system employing CuInSe 2(CIS) and CuGaSe 2(CGS) targets. Energy-dispersive X-ray fluorescence spectrometry (EDS-XRF) confirmed that the CIGS films had different Ga/(In + Ga) ratios, which were varied by the sample configuration on the substrate and ranged from 0.2 to 0.9. X-ray diffraction and Raman spectroscopy revealed that the CIGS films had a pure chalcopyritemore » phase without any secondary phase such as Cu-Se or ordered vacancy compound (OVC), respectively. Furthermore, we found that the optical bandgap energies of the CIGS films determined by transmittance measurements ranged from 1.07 eV to 1.53 eV as the Ga/(In + Ga) ratio increased from 0.2 to 0.9, demonstrating that the one-step sputtering process using CIS and CGS targets is another simple route to control the bandgap energy of the CIGS absorber layer.« less

Enhanced sensitivity to dielectric function and thickness of absorbing thin films by combining total internal reflection ellipsometry with standard ellipsometry and reflectometry

NASA Astrophysics Data System (ADS)

Lizana, A.; Foldyna, M.; Stchakovsky, M.; Georges, B.; Nicolas, D.; Garcia-Caurel, E.

2013-03-01

High sensitivity of spectroscopic ellipsometry and reflectometry for the characterization of thin films can strongly decrease when layers, typically metals, absorb a significant fraction of the light. In this paper, we propose a solution to overcome this drawback using total internal reflection ellipsometry (TIRE) and exciting a surface longitudinal wave: a plasmon-polariton. As in the attenuated total reflectance technique, TIRE exploits a minimum in the intensity of reflected transversal magnetic (TM) polarized light and enhances the sensitivity of standard methods to thicknesses of absorbing films. Samples under study were stacks of three films, ZnO : Al/Ag/ZnO : Al, deposited on glass substrates. The thickness of the silver layer varied from sample to sample. We performed measurements with a UV-visible phase-modulated ellipsometer, an IR Mueller ellipsometer and a UV-NIR reflectometer. We used the variance-covariance formalism to evaluate the sensitivity of the ellipsometric data to different parameters of the optical model. Results have shown that using TIRE doubled the sensitivity to the silver layer thickness when compared with the standard ellipsometry. Moreover, the thickness of the ZnO : Al layer below the silver layer can be reliably quantified, unlike for the fit of the standard ellipsometry data, which is limited by the absorption of the silver layer.

Application of chitosan as biomaterial for active packaging of ethylene absorber

NASA Astrophysics Data System (ADS)

Warsiki, E.

2018-03-01

Chitosan was used for active packaging of ethylene absorber that can change the head space of food packaging to extend the shelf life. The purpose of this study was to develop active packaging from chitosan and KMnO4 and apply the active film to package tomatoes. Active film was prepared by mixing chitosan 6 g, 140 mL of acetic acid 1%, 60 mL of aquadest, 2 mL sorbitol, and KMnO4 with concentration of 3 g, 5 g, and 7 g. After 5 days of storage, the film used to wrap the tomatoes was sweated. The best formulation to absorb the ethylene was made from 7 g of KMnO4 since it could inhibit tomatoes from shortly ripening compared to other formulations. The fruits were packed at room temperature had a high hardness as much as 17,79 mm/50mg/5s compared to the control of 3,47 mm/50mg/5s, while at the refrigerator, the tomato had lower hardness value of the 2,72 mm/50mg/5s compared to the control of 4,29 mm/50mg/5s. Addition of KMnO4 on the film could maintain the value °Hue either for all treated sample and control in the range of the yellow to red.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Targove, J.D.

The columnar microstructure of most thermally evaporated thin films detrimentally affects many of their properties through a reduction in packing density. In this work, the author investigated ion-assisted deposition as a means of disrupting this columnar growth for a number of coating materials. A Kaufman hot-cathode ion source bombarded thermally evaporated films with low-energy (<1000 eV) positive ions during deposition in a cryopumped box coater. The author investigated MgF/sub 2/, Na/sub 3/AlF/sub 6/, AlF/sub 3/, LaF/sub 3/,CeF/sub 3/,NdF/sub 3/,Al/sub 2/O/sub 3/, and AlN. Argon ion bombardment of the fluoride coatings increased their packing densities dramatically. He achieved packing densities nearmore » unity without significant absorption for MgF/sub 2/,LaF/sub 3/, and NdF/sub 3/, while Na/sub 3/AlF/sub 6/,AlF/sub 3/, and CeF/sub 3/ began to absorb before unity packing density could be achieved. Fluorine was preferentially sputtered by the ion bombardment, creating anion vacancies. The films adsorbed water vapor and hydroxyl radicals from the residual chamber atmosphere. These filled the vacancy sites, eliminating absorption in the visible, but the oxygen complexes caused increased absorption in the ultraviolet. For LaF/sub 3/ and NdF/sub 3/, a sufficient amount of oxygen caused a phase transformation from the fluoride phase to an oxyfluoride phase.« less

Annealed CVD molybdenum thin film surface

DOEpatents

Carver, Gary E.; Seraphin, Bernhard O.

1984-01-01

Molybdenum thin films deposited by pyrolytic decomposition of Mo(CO).sub.6 attain, after anneal in a reducing atmosphere at temperatures greater than 700.degree. C., infrared reflectance values greater than reflectance of supersmooth bulk molybdenum. Black molybdenum films deposited under oxidizing conditions and annealed, when covered with an anti-reflecting coating, approach the ideal solar collector characteristic of visible light absorber and infrared energy reflector.

Rough gold films as broadband absorbers for plasmonic enhancement of TiO2 photocurrent over 400–800 nm

PubMed Central

Tan, Furui; Li, Tenghao; Wang, Ning; Lai, Sin Ki; Tsoi, Chi Chung; Yu, Weixing; Zhang, Xuming

2016-01-01

Recent years have witnessed an increasing interest in highly-efficient absorbers of visible light for the conversion of solar energy into electrochemical energy. This study presents a TiO2-Au bilayer that consists of a rough Au film under a TiO2 film, which aims to enhance the photocurrent of TiO2 over the whole visible region and may be the first attempt to use rough Au films to sensitize TiO2. Experiments show that the bilayer structure gives the optimal optical and photoelectrochemical performance when the TiO2 layer is 30 nm thick and the Au film is 100 nm, measuring the absorption 80–90% over 400–800 nm and the photocurrent intensity of 15 μA·cm−2, much better than those of the TiO2-AuNP hybrid (i.e., Au nanoparticle covered by the TiO2 film) and the bare TiO2 film. The superior properties of the TiO2-Au bilayer can be attributed to the rough Au film as the plasmonic visible-light sensitizer and the photoactive TiO2 film as the electron accepter. As the Au film is fully covered by the TiO2 film, the TiO2-Au bilayer avoids the photocorrosion and leakage of Au materials and is expected to be stable for long-term operation, making it an excellent photoelectrode for the conversion of solar energy into electrochemical energy in the applications of water splitting, photocatalysis and photosynthesis. PMID:27608836

Deposition and characterization of far-infrared absorbing gold black films

NASA Technical Reports Server (NTRS)

Advena, Donna J.; Bly, Vincent T.; Cox, J. T.

1993-01-01

A process is described for producing gold black films with high absorptance in the far IR. The optical and electrical properties of these films have been studied with particular emphasis on the absorptance of films at wavelengths as long as 50 microns. A substantial decrease in absorptance near 50 microns has been observed for pure gold black films on aging in air. This degradation can be largely avoided by alloying the gold with a small percentage of copper during the deposition. Preliminary results on two methods for delineating gold black films are also presented.

Structure and optical properties of ZnO with silver nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyadov, N. M., E-mail: nik061287@mail.ru; Gumarov, A. I.; Kashapov, R. N.

Textured nanocrystalline ZnO thin films are synthesized by ion beam assisted deposition. According to X-ray diffraction data, the crystallite size is ∼25 nm. Thin (∼15 nm) ZnO layers containing Ag nanoparticles are formed in a thin surface region of the films by the implantation of Ag ions with an energy of 30 keV and a dose in the range (0.25–1) × 10{sup 17} ion/cm{sup 2}. The structure and optical properties of the layers are studied. Histograms of the size distribution of Ag nanoparticles are obtained. The average size of the Ag nanoparticles varies from 0.5 to 1.5–2 nm depending onmore » the Ag-ion implantation dose. The optical transmittance of the samples in the visible and ultraviolet regions increases, as the implantation dose is increased. The spectra of the absorption coefficient of the implanted films are calculated in the context of the (absorbing film)/(transparent substrate) model. It is found that the main changes in the optical-density spectra occur in the region of ∼380 nm, in which the major contribution to absorption is made by Ag nanoparticles smaller than 0.75 nm in diameter. In this spectral region, absorption gradually decreases, as the Ag-ion irradiation dose is increased. This is attributed to an increase in the average size of the Ag nanoparticles. It is established that the broad surface-plasmon-resonance absorption bands typical of nanocomposite ZnO films with Ag nanoparticles synthesized by ion implantation are defined by the fact that the size of the nanoparticles formed does not exceed 1.5–2 nm.« less

Characterization and device performance of (AgCu)(InGa)Se2 absorber layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanket, Gregory; Boyle, Jonathan H.; Shafarman, William N.

The study of (AgCu)(InGa)Se2 absorber layers is of interest in that Ag-chalcopyrites exhibit both wider bandgaps and lower melting points than their Cu counterparts. (AgCu)(InGa)Se2 absorber layers were deposited over the composition range 0 < Ag/(Ag+Cu) < 1 and 0.3 < Ga/(In+Ga) < 1.0 using a variety of elemental co-evaporation processes. Films were found to be singlephase over the entire composition range, in contrast to prior studies. Devices with Ga content 0.3 < Ga/(In+Ga) <0.5 tolerated Ag incorporation up to Ag/(Ag+Cu) = 0.5 without appreciable performance loss. Ag-containing films with Ga/(In+Ga) = 0.8 showed improved device characteristics over Cu-only controlmore » samples, in particular a 30-40% increase in short-circuit current. An absorber layer with composition Ag/(Ag+Cu) = 0.75 and Ga/(In+Ga) = 0.8 yielded a device with VOC = 890 mV, JSC = 20.5mA/cm2, fill factor = 71.3%, and η = 13.0%.« less

Thermodynamic Evaluation of Hydrogen Absorption by Niobium During SRF Fabrication

NASA Astrophysics Data System (ADS)

Ricker, R. E.; Myneni, G. R.

2011-03-01

The properties and performance of the ultra high purity Nb used to fabricate superconducting radio frequency (SRF) particle accelerator cavities have been found to vary with processing conditions. One hypothesis for these variations is that hydrogen, absorbed during processing, is responsible for this behavior. The key assumption behind this hypothesis is that niobium can absorb hydrogen from one or more of the processing environments. This paper reviews work examining the validity of this assumption. It was determined that Nb will spontaneously react with water producing adsorbed atomic hydrogen that is readily absorbed into the metal. The passivating oxide film normally prevents this reaction, but this film is frequently removed during processing and it is attacked by the fluoride ion used in the polishing solutions for SRF cavities. However, during electropolishing that cathodic reduction of hydrogen is transferred to the auxiliary electrode and this should suppress hydrogen absorption.

Thin film photovoltaic devices with a minimally conductive buffer layer

DOEpatents

Barnes, Teresa M.; Burst, James

2016-11-15

A thin film photovoltaic device (100) with a tunable, minimally conductive buffer (128) layer is provided. The photovoltaic device (100) may include a back contact (150), a transparent front contact stack (120), and an absorber (140) positioned between the front contact stack (120) and the back contact (150). The front contact stack (120) may include a low resistivity transparent conductive oxide (TCO) layer (124) and a buffer layer (128) that is proximate to the absorber layer (140). The photovoltaic device (100) may also include a window layer (130) between the buffer layer (128) and the absorber (140). In some cases, the buffer layer (128) is minimally conductive, with its resistivity being tunable, and the buffer layer (128) may be formed as an alloy from a host oxide and a high-permittivity oxide. The high-permittivity oxide may further be chosen to have a bandgap greater than the host oxide.

Perfect absorption in nanotextured thin films via Anderson-localized photon modes

NASA Astrophysics Data System (ADS)

Aeschlimann, Martin; Brixner, Tobias; Differt, Dominik; Heinzmann, Ulrich; Hensen, Matthias; Kramer, Christian; Lükermann, Florian; Melchior, Pascal; Pfeiffer, Walter; Piecuch, Martin; Schneider, Christian; Stiebig, Helmut; Strüber, Christian; Thielen, Philip

2015-10-01

The enhancement of light absorption in absorber layers is crucial in a number of applications, including photovoltaics and thermoelectrics. The efficient use of natural resources and physical constraints such as limited charge extraction in photovoltaic devices require thin but efficient absorbers. Among the many different strategies used, light diffraction and light localization at randomly nanotextured interfaces have been proposed to improve absorption. Although already exploited in commercial devices, the enhancement mechanism for devices with nanotextured interfaces is still subject to debate. Using coherent two-dimensional nanoscopy and coherent light scattering, we demonstrate the existence of localized photonic states in nanotextured amorphous silicon layers as used in commercial thin-film solar cells. Resonant absorption in these states accounts for the enhanced absorption in the long-wavelength cutoff region. Our observations establish that Anderson localization—that is, strong localization—is a highly efficient resonant absorption enhancement mechanism offering interesting opportunities for the design of efficient future absorber layers.

UV absorption control of thin film growth

DOEpatents

Biefeld, Robert M.; Hebner, Gregory A.; Killeen, Kevin P.; Zuhoski, Steven P.

1991-01-01

A system for monitoring and controlling the rate of growth of thin films in an atmosphere of reactant gases measures the UV absorbance of the atmosphere and calculates the partial pressure of the gases. The flow of reactant gases is controlled in response to the partial pressure.

Perovskite Solar Cells | Photovoltaic Research | NREL

Science.gov Websites

& Devices pages: High-Efficiency Crystalline PV Polycrystalline Thin-Film PV Perovskite and Organic -Defect Hybrid Organic/Inorganic Perovskite Films as PV Absorbers. (FY 2015FY 2016). In collaboration with organic metal halide perovskite (see article). Ultrahigh-Efficiency and Low-Cost Polycrystalline Halide

Optical Physics of Cu(In,Ga)Se2 Solar Cells and Their Layer Components

NASA Astrophysics Data System (ADS)

Ibdah, Abedl-Rahman

Polycrystalline Cu(In1-xGax)Se 2 (CIGS) thin film technology has emerged as a promising candidate for low cost and high performance solar modules. The efficiency of CIGS solar cells is strongly influenced by several key factors. Among these factors include Ga composition and its profile in the absorber layer, copper content in this layer, and the solar cell multilayer structure. As a result, tools for the characterization of thin film CIGS solar cells and their layer components are becoming increasingly essential in research and manufacturing. Spectroscopic ellipsometry is a non-invasive technique that can serve as an accurate probe of component layer optical properties and multilayer structures, and can be applied as a diagnostic tool for real-time, in-line, and off-line monitoring and analysis in small area solar cell fabrication as well as in large area photovoltaics manufacturing. Implementation of spectroscopic ellipsometry provides unique insights into the properties of complete solar cell multilayer structures and their layer components. These insights can improve our understanding of solar cell structures, overcome challenges associated with solar cell fabrication, and assist in process monitoring and control on a production line. In this dissertation research, Cu(In,Ga)Se2 films with different Cu contents have been prepared by the one stage co-evaporation process. These films have been studied by real time spectroscopic ellipsometry (RTSE) during deposition, and by in-situ SE at the deposition temperature as well as at room temperature to extract the dielectric functions (epsilon1, epsilon 2) of the thin film materials. Analytical expressions for the room temperature dielectric functions were developed, and the free parameters that describe these analytical functions were in turn expressed as functions of the Cu content. As a result of this parameterization, the dielectric function spectra (epsilon 1, epsilon2) can be predicted for any desired composition within the range of the samples investigated. This capability was applied for mapping the structural and compositional variations of CIGS thin films deposited over a 10 cm x 10 cm substrate area. In another application presented in this dissertation, a non-invasive method utilizing ex-situ spectroscopic ellipsometry analysis has been developed and applied to determine non-destructively the Ga compositional profile in CIGS absorbers. The method employs parameterized dielectric function spectra (epsilon1, epsilon2) of CIGS versus Ga content to probe the compositional variation with depth into the absorber. In addition, a methodology for prediction of the external quantum efficiency (QE) including optical gains and losses for a CIGS solar cell has been developed. The methodology utilizes ex-situ spectroscopic ellipsometry analysis of a complete solar cell, with no free parameters, to deduce the multilayer solar cell structure non-invasively and simulate optical light absorption in each of the layer components. In the case of high efficiency CIGS solar cells, with minimal electronic losses, QE spectra are predicted from the sum of optical absorption in the active layer components. For such solar cells with ideal photo-generated charge carrier collection, the SE-predicted QE spectra are excellent representation of the measured ones. Since the QE spectra as well as the short circuit current density (Jsc) can be calculated directly from SE analysis results, then the predicted QE from SE can be compared with the experimental QE to evaluate electronic losses based on the difference between the spectra. Moreover, the calculated Jsc can be used as a key parameter for the design and optimization of anti-reflection coating structures. Because the long term production potential of CIGS solar modules may be limited by the availability of indium, it becomes important to reduce the thickness of the CIGS absorber layer. Thickness reduction would reduce the quantity of indium required for production which would in turn reduce costs. A decrease in short-circuit current density (Jsc) is expected, however, upon thinning the CIGS absorber due to incomplete absorption. To clarify the limits of obtainable Jsc in ultra-thin CIGS solar cells with Mo back contacts, optical properties and multilayer structural data are deduced via spectroscopic ellipsometry analysis and used to predict the QE spectra and maximum obtainable Jsc values upon thinning the absorber. Moreover, SE-guided optical design of ultra-thin CIGS solar cells has been demonstrated. In the case of solar cells fabricated on Mo, thinning the absorber in a CIGS solar cell is associated with significant optical losses in the Mo containing back contact layers. This is due in part to the poor optical reflectance of Mo. Such optical losses may be reduced by employing a back contact design with improved reflectance. Thus, alternative novel solar cell structures with ultra-thin absorbers and improved back contact reflectance have been designed and investigated using SE and the optical modeling methods. In addition to optical losses, electronic losses in the ultra-thin solar cells have been evaluated. By separating the absorber layer into sub-layer regions (for example, near-junction, bulk, and near-back-contact) and varying carrier collection probability in these regions, the contribution of each region to the current can be estimated. Based on this separation, the origin of the electronic losses has been identified as near the back contact.

Microbial imprinted polypyrrole/poly(3-methylthiophene) composite films for the detection of Bacillus endospores.

PubMed

Namvar, Azadeh; Warriner, Keith

2007-04-15

The fabrication of Bacillus subtilis endospore imprinted conducting polymer films and subsequent electrochemical detection of bound spores is reported. Imprinted films were prepared by absorbing spores on the surface of glassy carbon electrodes upon which a polypyrrole, followed by a poly(3-methylthiophene), layer were electrochemically deposited. Spore template release was achieved through soaking the modified electrode in DMSO. Binding of endospores to imprinted films could be detected via impedance spectroscopy by monitoring changes in Y'' (susceptance) using Mn(II)Cl2 (0.5M pH 3) as the supporting electrolyte. Here, the change in Y'' could be correlated to spore densities between 10(4) and 10(7)cfu/ml. More sensitive detection of absorbed spores was achieved by following endospore germination via changes in film charge as measured using cyclic voltammetry. Here, imprinted films were submerged in spore suspensions to permit absorption, heat activated at 70 degrees C for 10 min prior to transferring to an electrochemical cell containing germination activators. By using the assay format it was possible to detect 10(2)cfu/ml. The observed changes in film charge could be attributed to the interaction of the supporting conducting polymer with dipicolinic acid (DPA) and other constituents released from the core in the course of germination. In all cases, it was not possible to regenerate the imprinted films without losing electrode response. In summary, the study has provided proof-of-concept for fabricating microbial imprinted films using conducting polymers.

Integrated Microcalorimeters Using Ir TES And Sn Mushroom Absorbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C.; Bogorin, D.; Galeazzi, M.

2006-09-07

Cryogenic microcalorimeters have the potential to meet the requirements of future x-ray missions. The University of Miami has recently started a program to fabricate fully integrated microcalorimeter arrays. We deposit high purity iridium thin film as Transition Edge Sensors (TES). We chose iridium because it has a bulk transition temperature of 112 mK and we expect single layer TES to have good reproducibility and long term stability. Also we use integrated tin film in a mushroom geometry as the absorbers to get high filling factor, low heat capacity and easy array manufacturing process. We present here our preliminary results inmore » both areas.« less

Enhancement of absorption and color contrast in ultra-thin highly absorbing optical coatings

NASA Astrophysics Data System (ADS)

Kats, Mikhail A.; Byrnes, Steven J.; Blanchard, Romain; Kolle, Mathias; Genevet, Patrice; Aizenberg, Joanna; Capasso, Federico

2013-09-01

Recently a new class of optical interference coatings was introduced which comprises ultra-thin, highly absorbing dielectric layers on metal substrates. We show that these lossy coatings can be augmented by an additional transparent subwavelength layer. We fabricated a sample comprising a gold substrate, an ultra-thin film of germanium with a thickness gradient, and several alumina films. The experimental reflectivity spectra showed that the additional alumina layer increases the color range that can be obtained, in agreement with calculations. More generally, this transparent layer can be used to enhance optical absorption, protect against erosion, or as a transparent electrode for optoelectronic devices.

The impact of viscosity on the combined heat, mass and momentum transfer in laminar liquid falling films

NASA Astrophysics Data System (ADS)

Mittermaier, M.; Ziegler, F.

2018-04-01

In this article we present a model describing a laminar film flow over a vertical isothermal plate whilst heat and mass transfer is occurring. We focus on a formulation where most common assumptions, such as constant property data and constant film thickness, have been cancelled. The hydrodynamic model results in longitudinal and transversal velocity components and their evolution in the entrance region. Heat and mass transfer occurs simultaneously and is modelled with respect to release of differential heat of solution as well as heat flow due to interdiffusion. The numerical solution is obtained by utilising a Newton-Raphson method to solve the finite difference formulation of the governing equations. Mass transfer across the film affects the development of both longitudinal and transversal velocity components. The hydrodynamics are modelled using a boundary layer approximation of the Navier-Stokes equations. The significance of simplifications on the hydrodynamic model are illustrated and discussed using a fully developed velocity profile (Nusselt flow) and a plug flow at the inlet for comparison. Even if a Nusselt profile is assumed, it develops further since mass is absorbed or desorbed. It is found that the onset of absorption occurs at shorter flow length when applying a plug flow at the inlet. If the film is initially in equilibrium, this results in a 9.3% increase in absorbed mass over a length of 0.03 m as compared with the Nusselt flow. A fluid with a viscosity five times the one of lithium bromide solution but sharing comparable properties apart from that, leads to lower overall heat and mass transfer rates. If the respective fluids are saturated at the inlet, the accumulated mass flux absorbed by lithium bromide solution is 2.2 times higher than the one absorbed by a high viscous fluid. However, when a plug flow is applied and the fluid is sub-cooled, ab initio the absorbed mass flux is slightly higher for a high viscous fluid. Assuming a sub-cooling of 3 K at the inlet, lithium bromide solution now only performs around 11% better as compared with a high viscous fluid over the considered length of 0.03 m. The code may be downloaded from: https://github.com/mittermaier/hmt.

Atomic Oxygen Interactions With Silicone Contamination on Spacecraft in Low Earth Orbit Studied

NASA Technical Reports Server (NTRS)

Banks, Bruce A.

2001-01-01

Silicones have been widely used on spacecraft as potting compounds, adhesives, seals, gaskets, hydrophobic surfaces, and atomic oxygen protective coatings. Contamination of optical and thermal control surfaces on spacecraft in low Earth orbit (LEO) has been an ever-present problem as a result of the interaction of atomic oxygen with volatile species from silicones and hydrocarbons onboard spacecraft. These interactions can deposit a contaminant that is a risk to spacecraft performance because it can form an optically absorbing film on the surfaces of Sun sensors, star trackers, or optical components or can increase the solar absorptance of thermal control surfaces. The transmittance, absorptance, and reflectance of such contaminant films seem to vary widely from very transparent SiOx films to much more absorbing SiOx-based films that contain hydrocarbons. At the NASA Glenn Research Center, silicone contamination that was oxidized by atomic oxygen has been examined from LEO spacecraft (including the Long Duration Exposure Facility and the Mir space station solar arrays) and from ground laboratory LEO simulations. The findings resulted in the development of predictive models that may help explain the underlying issues and effects. Atomic oxygen interactions with silicone volatiles and mixtures of silicone and hydrocarbon volatiles produce glassy SiOx-based contaminant coatings. The addition of hydrocarbon volatiles in the presence of silicone volatiles appears to cause much more absorbing (and consequently less transmitting) contaminant films than when no hydrocarbon volatiles are present. On the basis of the LDEF and Mir results, conditions of high atomic oxygen flux relative to low contaminant flux appear to result in more transparent contaminant films than do conditions of low atomic oxygen flux with high contaminant flux. Modeling predictions indicate that the deposition of contaminant films early in a LEO flight should depend much more on atomic oxygen flux than it does later in a mission.

Reconstructing the energy band electronic structure of pulsed laser deposited CZTS thin films intended for solar cell absorber applications

NASA Astrophysics Data System (ADS)

Pandiyan, Rajesh; Oulad Elhmaidi, Zakaria; Sekkat, Zouheir; Abd-lefdil, Mohammed; El Khakani, My Ali

2017-02-01

We report here on the use of pulsed KrF-laser deposition (PLD) technique for the growth of high-quality Cu2ZnSnS4 (CZTS) thin films onto Si, and glass substrates without resorting to any post sulfurization process. The PLD-CZTS films were deposited at room temperature (RT) and then subjected to post annealing at different temperatures ranging from 200 to 500 °C in Argon atmosphere. The X-ray diffraction and Raman spectroscopy confirmed that the PLD films crystallize in the characteristic kesterite CZTS structure regardless of their annealing temperature (Ta), but their crystallinity is much improved for Ta ≥ 400 °C. The PLD-CZTS films were found to exhibit a relatively dense morphology with a surface roughness (RMS) that increases with Ta (from ∼14 nm at RT to 70 nm at Ta = 500 °C with a value around 40 nm for Ta = 300-400 °C). The optical bandgap of the PLD-CZTS films, was derived from UV-vis transmission spectra analysis, and found to decrease from 1.73 eV for non-annealed films to ∼1.58 eV for those annealed at Ta = 300 °C. These band gap values are very close to the optimum value needed for an ideal solar cell absorber. In order to achieve a complete reconstruction of the one-dimensional energy band structure of these PLD-CZTS absorbers, we have combined both XPS and UPS spectroscopies to determine their chemical bondings, the position of their valence band maximum (relative to Fermi level), and their work function values. This enabled us to sketch out, as accurately as possible, the band alignment of the heterojunction interface formed between CZTS and both CdS and ZnS buffer layer materials.

Design, construction, and testing of the direct absorption receiver panel research experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chavez, J.M.; Rush, E.E.; Matthews, C.W.

1990-01-01

A panel research experiment (PRE) was designed, built, and tested as a scaled-down model of a direct absorption receiver (DAR). The PRE is a 3-MW{sub t}DAR experiment that will allow flow testing with molten nitrate salt and provide a test bed for DAR testing with actual solar heating. In a solar central receiver system DAR, the heat absorbing fluid (a blackened molten nitrate salt) flows in a thin film down a vertical panel (rather than through tubes as in conventional receiver designs) and absorbs the concentrated solar flux directly. The ability of the flowing salt film to absorb flux directly.more » The ability of the flowing salt film to absorb the incident solar flux depends on the panel design, hydraulic and thermal fluid flow characteristics, and fluid blackener properties. Testing of the PRE is being conducted to demonstrate the engineering feasibility of the DAR concept. The DAR concept is being investigated because it offers numerous potential performance and economic advantages for production of electricity when compared to other solar receiver designs. The PRE utilized a 1-m wide by 6-m long absorber panel. The salt flow tests are being used to investigate component performance, panel deformations, and fluid stability. Salt flow testing has demonstrated that all the DAR components work as designed and that there are fluid stability issues that need to be addressed. Future solar testing will include steady-state and transient experiments, thermal loss measurements, responses to severe flux and temperature gradients and determination of peak flux capability, and optimized operation. In this paper, we describe the design, construction, and some preliminary flow test results of the Panel Research Experiment. 11 refs., 8 figs., 2 tabs.« less

Effect of assistant rf field on phase composition of iron nitride film prepared by magnetron sputtering process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, W.L.; Zheng, F.; Fei, W.D.

2006-01-15

Fe-N thin films were fabricated using a direct current magnetron sputtering process assisted by a radio-frequency (rf) field. The effect of the rf field on the phase composition of the films was investigated. The results indicate that with the assistance of the rf field, various kinds of iron nitrides can be obtained in the films, including {alpha}{sup '}-Fe-N, {alpha}{sup ''}-Fe{sub 16}N{sub 2}, {xi}-Fe{sub 2}N, {epsilon}-Fe{sub 3}N, and {gamma}{sup ''}-FeN with ZnS structure. It was found that the rf field greatly benefits the formation of iron nitrides in the Fe-N films.

Photovoltaic cells employing zinc phosphide

DOEpatents

Barnett, Allen M.; Catalano, Anthony W.; Dalal, Vikram L.; Masi, James V.; Meakin, John D.; Hall, Robert B.

1984-01-01

A photovoltaic cell having a zinc phosphide absorber. The zinc phosphide can be a single or multiple crystal slice or a thin polycrystalline film. The cell can be a Schottky barrier, heterojunction or homojunction device. Methods for synthesizing and crystallizing zinc phosphide are disclosed as well as a method for forming thin films.

A Film Canister Colorimeter.

ERIC Educational Resources Information Center

Gordon, James; James, Alan; Harman, Stephanie; Weiss, Kristen

2002-01-01

A low-cost, low-tech colorimeter was constructed from a film canister. The student-constructed colorimeter was used to show the Beer-Lambert relationship between absorbance and concentration and to calculate the value of the molar absorptivity for permanganate at the wavelength emission maximum for an LED. Makes comparisons between this instrument…

New noninvasive approach assessing in vivo sun protection factor (SPF) using diffuse reflectance spectroscopy (DRS) and in vitro transmission.

PubMed

Ruvolo Junior, Eduardo; Kollias, Nikiforos; Cole, Curtis

2014-08-01

In the past 56 years, many different in vitro methodologies have been developed and published to assess the sun protection factor (SPF) of products, but there is no method that has 1:1 correlation with in vivo measurements. Spectroscopic techniques have been used to noninvasively assess the UVA protection factor with good correlation to in vivo UVA-PF methodologies. To assess the SPF of sunscreen product by diffuse reflectance spectroscopy (DRS) technique, it is necessary to also determine the absorbance spectrum of the test material in the UVB portion of the spectrum (290-320 nm). However, because of the high absorbance characteristics of the stratum corneum and epidermis, the human skin does not remit enough UVB radiation to be used to measure the absorption spectrum of the applied product on skin. In this work, we present a new method combining the evaluation of the absolute UVA absorption spectrum, as measured by DRS with the spectral absorbance 'shape' of the UVB absorbance of the test material as determined with current in vitro thin film spectroscopy. The measurement of the in vivo UVA absorption spectrum involves the assessment of the remitted intensity of monochromatic UVA radiation (320-400 nm) before and after a sunscreen product was applied on skin using a spectrofluorimeter Fluorolog 3, FL3-22 (Yvon Horiba, Edison, NJ, USA). The probe geometry assures that light scattering products as well as colored products may be correctly assessed. This methodology has been extensively tested, validated, and reported in the literature. The in vitro absorption spectrum of the sunscreen samples and polyvinyl chloride (PVC) films 'surrogate' sunscreen standards were measured using Labsphere® UV-2000S (Labsphere, North Sutton, NH, USA). Sunscreens samples were tested using PMMA Helioplates (Helioscience, Marseille, France) as substrates. The UVB absorbance spectrum (Labsphere) is 'attached' to the UVA absorbance spectrum (diffuse reflectance) with the UVB absorbance matched to the UVA absorbance at 340 nm to complete the full spectral absorbance from which an estimate the SPF of the product can be calculated. Seventeen test materials with known in vivo SPF values were tested. Two of the tested products were PVC sunscreen thin films with 10-15 micrometers thickness and were used to investigate the absorption spectrum of these films when applied on different reflectance surfaces. Similar to the human in vivo SPF test, the developed methodology suggests limiting the use on Fitzpatrick skin phototypes I to III. The correlation of this new method with in vivo clinical SPF values was 0.98 (r2) with a slope of 1.007. This new methodology provides a new approach to determine SPF values without the extensive UV irradiation procedures (and biological responses) currently used to establish sunscreen efficacy. Further work will be conducted to establish methods for evaluation of products that are not photostable. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Combinatorial development of Cu2SnS3 as an earth abundant photovoltaic absorber

NASA Astrophysics Data System (ADS)

Baranowski, Lauryn L.

The development of high efficiency, earth abundant photovoltaic absorbers is critical if photovoltaics are to be implemented on the TW scale. Although traditional thin films absorbers such as Cu(In,Ga)Se2 and CdTe have achieved over 20% device efficiencies, the ultimately scalability of these devices may be limited by elemental scarcity and toxicity issues. To date, the most successful earth abundant thin film absorber is Cu2ZnSn(S,Se) 4, which has achieved 12.6% efficiency as of 2014. However, chemical complexity and disorder issues with this material have made the path to higher efficiency CZTSSe devices unclear. As a result, many researchers are now exploring alternative earth abundant absorber materials. In this thesis, we apply our "rapid development" methodology to the exploration of alternative photovoltaic absorbers. The rapid development (RD) methodology, consisting of exploration, research, and development stages, uses complementary theory and experiment to assess candidate materials and down-select in each stage. The overall result is that, in the time span of ~2-3 years, we are able to rapidly go from tens of possible absorber materials to 1-2 working PV device prototypes. Here, we demonstrate the RD approach as applied to the Cu-Sn-S system. We begin our investigation of the Cu-Sn-S system by evaluating the thermodynamic stability, electrical transport, electronic structure, and optical and defect properties of candidate materials using complementary theory and experiment. We find that Cu2SnS3 is the most promising absorber candidate because of its strong optical absorption, tunable doping, and wide stability range. Our other candidate compounds suffer from serious flaws that preclude them from being successful photovoltaic absorbers, including too high experimental conductivity (Cu4SnS4), or poor hole transport and low absorption coefficient (Cu4Sn7S16). Next, we investigate the doping and defect physics of Cu2SnS 3. We identify the origins of the changes in doping in sputtered cubic Cu2SnS3 thin films using combinatorial experiments and first-principles theory. High S chemical potential during deposition decreases the enthalpy of formation of Cu vacancies, which are the dominant acceptor defect in Cu2SnS3. Unexpectedly, under Cu-rich conditions, alloying with an isostructural (cubic) metallic Cu3SnS4 phase occurs, causing high levels of p-type doping. Both of these effects lead to undesirably high electrical conductivity, thus Cu2SnS 3 films must be grown both S- and Cu-poor in order to achieve moderate hole concentrations. To understand the effects of structural disorder on the transport properties in Cu2SnS3 we develop synthetic techniques to control this disorder, and observe improvements in the majority carrier (hole) transport. However, when the minority carrier (electron) transport was investigated, minimal differences were observed between the ordered and disordered Cu 2SnS3. By combining these results with first-principles and Monte Carlo theoretical calculations, we are able to conclude that even ostensibly "ordered" Cu2SnS3 displays minority carrier transport properties corresponding to the disordered structure. The presence of extended planar defects in all samples, observed in TEM imaging, suggests that disorder is present even when it is not detectable using traditional structural characterization methods. Lastly, we attempt to integrate our Cu2SnS3 films into photovoltaic devices, which requires translating our growth techniques to conductive substrates. We survey a wide range of possible conductive substrates, but are not able to find a suitable back contact for Cu2SnS 3 device integration, due to issues such as secondary phase formation and delamination. From a survey of successful Cu2SnS3 device literature, we are able to conclude that the issue may lie with our binary sputtering method in which the ternary compound formation and the film growth occur simultaneously. At the conclusion of this study, we eliminated Cu2SnS as an absorber candidate for future development. However, the two main issues we encountered (eliminating structural disorder and difficulty growing on conductive back contacts) may both be related to our binary sputtering technique. We expect that interest in Cu2SnS3-based photovoltaics will continue to grow, and that further scientific understanding may shed light on our particular difficulties. In the future, the RD methodology has the potential to greatly accelerate the discovery and development of non-traditional thin film absorbers, and may enable high impact material breakthroughs.

Structured Metal Film as Perfect Absorber

NASA Astrophysics Data System (ADS)

Xiong, Xiang; Jiang, Shang-Chi; Peng, Ru-Wen; Wang, Mu

2014-03-01

With standing U-shaped resonators, fish-spear-like resonator has been designed for the first time as the building block to assemble perfect absorbers. The samples have been fabricated with two-photon polymerization process and FTIR measurement results support the effectiveness of the perfect absorber design. In such a structure the polarization-dependent resonance occurs between the tines of the spears instead of the conventional design where the resonance occurs between the metallic layers separated by a dielectric interlayer. The incident light neither transmits nor reflects back which results in unit absorbance. The power of light is trapped between the tines of spears and finally be absorbed. The whole structure is covered with a continuous metallic layer with good thermo-conductance, which provides an excellent approach to deal with heat dissipation, is enlightening in exploring metamaterial absorbers.

Optical properties and indentation hardness of thin-film acrylated epoxidized oil

NASA Astrophysics Data System (ADS)

Rahman, Mohammad Syuhaimi Ab.; Shaktur, Khaled Mohamed; Mohammad, Rahmah; Zalikha, Wan Aimi; Nawi, Norwimie; Mohd, Ahmad Faiza

2012-02-01

Epoxy acrylate has been widely used as optical resin for applications such as cladding, the core of a waveguide, and other photonic devices. In this study, sustainable resin from edible oil was used as an alternative to epoxy acrylate. Structural features and the transmission of planar thin-film resin from an ultraviolet-visible spectroscopy (UV-VIS) spectrometer were investigated upon UV exposure. It was found that high transmission still persists for all samples with and without an UV absorber for exposed and unexposed samples. The film was found to absorb strongly below 400 nm. A change in the cut-off wavelength was observed upon exposure. Thin-film hardness and its dynamic indentation in the load-unload mode with different test forces were evaluated. Vickers hardness and the elastic modulus were determined for unacrylated epoxidized soybean oil (ESO) and acrylated epoxidized soybean oil (AESO). It was found that the AESO has a higher Vickers hardness and elastic modulus than those of unacrylated thin film. The Vickers hardness and elastic modulus were found to increase as the applied test force increased. The refractive index, thickness, and modes present were characterized from a spin-coated planar thin film. The refractive index in the transverse electric mode (TE) and transverse magnetic mode (TM) were determined and compared for unacrylated and acrylated epoxidized oil.

Subtractive Plasma-Assisted-Etch Process for Developing High Performance Nanocrystalline Zinc-Oxide Thin-Film-Transistors

DTIC Science & Technology

2015-03-26

THIN - FILM - TRANSISTORS THESIS Thomas M. Donigan, First Lieutenant, USAF AFIT-ENG-MS-15-M-027 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR...DEVELOPING HIGH PERFORMANCE NANOCRYSTALLINE ZINC-OXIDE THIN - FILM - TRANSISTORS THESIS Presented to the Faculty Department of Electrical and...15-M-027 SUBTRACTIVE PLASMA-ASSISTED-ETCH PROCESS FOR DEVELOPING HIGH PERFORMANCE NANOCRYSTALLINE ZINC-OXIDE THIN - FILM - TRANSISTORS

Electromagnetic and optical characteristics of Nb5+-doped double-crossover and salmon DNA thin films

NASA Astrophysics Data System (ADS)

Babu Mitta, Sekhar; Reddy Dugasani, Sreekantha; Jung, Soon-Gil; Vellampatti, Srivithya; Park, Tuson; Park, Sung Ha

2017-10-01

We report the fabrication and physical characteristics of niobium ion (Nb5+)-doped double-crossover DNA (DX-DNA) and salmon DNA (SDNA) thin films. Different concentrations of Nb5+ ([Nb5+]) are coordinated into the DNA molecules, and the thin films are fabricated via substrate-assisted growth (DX-DNA) and drop-casting (SDNA) on oxygen plasma treated substrates. We conducted atomic force microscopy to estimate the optimum concentration of Nb5+ ([Nb5+]O = 0.08 mM) in Nb5+-doped DX-DNA thin films, up to which the DX-DNA lattices maintain their structures without deformation. X-ray photoelectron spectroscopy (XPS) was performed to probe the chemical nature of the intercalated Nb5+ in the SDNA thin films. The change in peak intensities and the shift in binding energy were witnessed in XPS spectra to explicate the binding and charge transfer mechanisms between Nb5+ and SDNA molecules. UV-visible, Raman, and photoluminescence (PL) spectra were measured to determine the optical properties and thus investigate the binding modes, Nb5+ coordination sites in Nb5+-doped SDNA thin films, and energy transfer mechanisms, respectively. As [Nb5+] increases, the absorbance peak intensities monotonically increase until ˜[Nb5+]O and then decrease. However, from the Raman measurements, the peak intensities gradually decrease with an increase in [Nb5+] to reveal the binding mechanism and binding sites of metal ions in the SDNA molecules. From the PL, we observe the emission intensities to reduce them at up to ˜[Nb5+]O and then increase after that, expecting the energy transfer between the Nb5+ and SDNA molecules. The current-voltage measurement shows a significant increase in the current observed as [Nb5+] increases in the SDNA thin films when compared to that of pristine SDNA thin films. Finally, we investigate the temperature dependent magnetization in which the Nb5+-doped SDNA thin films reveal weak ferromagnetism due to the existence of tiny magnetic dipoles in the Nb5+-doped SDNA complex.

Hydrogen incorporation by plasma treatment gives mesoporous black TiO 2 thin films with visible photoelectrochemical water oxidation activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Islam, Syed Z.; Reed, Allen; Nagpure, Suraj

In this work, we use neutron reflectometry (NR) to investigate the roles of hydrogen in plasma treated hydrogen doped mesoporous black titania thin films in their visible light absorption and enhanced photoactivity for water oxidation. The cubic ordered mesoporous TiO 2 thin films are prepared by a surfactant-templated sol-gel method and are treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate that H 2 plasma treatment makes TiO 2 films black, with broad-spectrum enhancementmore » of visible light absorption, and XPS analysis shows peak for Ti 3+ state in treated films. The presence of hydrogen in black mesoporous titania (H-TiO 2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO 2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO 2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide the first direct evidence that the dramatic change in visible light absorbance of H-treated black TiO 2 is accompanied by significant hydrogen uptake and not just Ti 3+ generation or surface disordering.« less

Hydrogen incorporation by plasma treatment gives mesoporous black TiO 2 thin films with visible photoelectrochemical water oxidation activity

DOE PAGES

Islam, Syed Z.; Reed, Allen; Nagpure, Suraj; ...

2017-10-26

In this work, we use neutron reflectometry (NR) to investigate the roles of hydrogen in plasma treated hydrogen doped mesoporous black titania thin films in their visible light absorption and enhanced photoactivity for water oxidation. The cubic ordered mesoporous TiO 2 thin films are prepared by a surfactant-templated sol-gel method and are treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate that H 2 plasma treatment makes TiO 2 films black, with broad-spectrum enhancementmore » of visible light absorption, and XPS analysis shows peak for Ti 3+ state in treated films. The presence of hydrogen in black mesoporous titania (H-TiO 2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO 2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO 2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide the first direct evidence that the dramatic change in visible light absorbance of H-treated black TiO 2 is accompanied by significant hydrogen uptake and not just Ti 3+ generation or surface disordering.« less

Hydrogen incorporation by plasma treatment gives mesoporous black TiO 2 thin films with visible photoelectrochemical water oxidation activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Islam, Syed Z.; Reed, Allen; Nagpure, Suraj

2018-05-01

In this work, we use neutron reflectometry (NR) to investigate the roles of hydrogen in plasma treated hydrogen doped mesoporous black titania thin films in their visible light absorption and enhanced photoactivity for water oxidation. The cubic ordered mesoporous TiO2 thin films are prepared by a surfactant-templated sol-gel method and are treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate that H2 plasma treatment makes TiO2 films black, with broad-spectrum enhancement of visible lightmore » absorption, and XPS analysis shows peak for Ti3+ state in treated films. The presence of hydrogen in black mesoporous titania (H-TiO2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide the first direct evidence that the dramatic change in visible light absorbance of H-treated black TiO2 is accompanied by significant hydrogen uptake and not just Ti3+ generation or surface disordering.« less

Simultaneous measurement of liquid absorbance and refractive index using a compact optofluidic probe.

PubMed

Malak, Maurine; Marty, Frédéric; Bourouina, Tarik; Angelescu, Dan

2013-07-21

We present a novel optical technique for simultaneously measuring the absorbance and the refractive index of a thin film using an infrared optofluidic probe. Experiments were carried on two different liquids and the results agree with the bibliographical data. The ultimate goal is to achieve a multi-functional micro-optical device for analytical applications.

The promise of solution-processed Fe 2GeS 4 thin films in iron chalcogenide photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Mimi; Berg, Dominik M.; Hwang, Po-Yu

The olivine Fe 2GeS 4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe 2GeS 4 precursor powders obtained via a simple solution-based process were converted to highly crystalline Fe 2GeS 4 powders upon a thermal treatment in controlled atmosphere. Thin films fabricated by dip coating in the Fe 2GeS 4 precursor dispersion and subjected to the same thermal treatment render high-purity Fe 2GeS 4 thin films with a band gap of 1.4 eV, measured by room-temperature photoluminescence. Using Fe 2GeS 4 thin films as the sole absorber in a solution-based solarmore » cell, open-circuit voltages of 361 mV are observed, while the use of the Fe 2GeS 4 films as counter electrodes in dye-sensitized solar cell constructs enhances the overall power conversion efficiency of the cell by a factor of five. Finally, this is the first report of a photovoltaic device based onFe 2GeS 4.« less

Chemical precursor impact on the properties of Cu{sub 2}ZnSnS{sub 4} absorber layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vashistha, Indu B., E-mail: indu-139@yahoo.com; Sharma, S. K.; Sharma, Mahesh C.

2016-04-13

In present work impact of different chemical precursor on the deposition of solar absorber layer Cu{sub 2}ZnSnS{sub 4} (CZTS) were studied by Chemical Bath Deposition (CBD) method without using expensive vacuum facilities and followed by annealing. As compared to the other deposition methods, CBD method is interesting one because it is simple, reproducible, non-hazardous, cost effective and well suited for producing large-area thin films at low temperatures, although effect of precursors and concentration plays a vital role in the deposition. So, the central theme of this work is optimizing and controlling of chemical reactions for different chemical precursors. Further Effectmore » of different chemical precursors i.e. sulphate and chloride is analyzed by structural, morphological, optical and electrical properties. The X-ray diffraction (XRD) of annealed CZTS thin film revealed that films were polycrystalline in nature with kestarite tetragonal crystal structure. The Atomic Force micrographs (AFM) images indicated total coverage compact film and as well as growth of crystals. The band gap of annealed CZTS films was found in the range of optimal band gap by absorption spectroscopy.« less

The promise of solution-processed Fe 2GeS 4 thin films in iron chalcogenide photovoltaics

DOE PAGES

Liu, Mimi; Berg, Dominik M.; Hwang, Po-Yu; ...

2018-02-06

The olivine Fe 2GeS 4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe 2GeS 4 precursor powders obtained via a simple solution-based process were converted to highly crystalline Fe 2GeS 4 powders upon a thermal treatment in controlled atmosphere. Thin films fabricated by dip coating in the Fe 2GeS 4 precursor dispersion and subjected to the same thermal treatment render high-purity Fe 2GeS 4 thin films with a band gap of 1.4 eV, measured by room-temperature photoluminescence. Using Fe 2GeS 4 thin films as the sole absorber in a solution-based solarmore » cell, open-circuit voltages of 361 mV are observed, while the use of the Fe 2GeS 4 films as counter electrodes in dye-sensitized solar cell constructs enhances the overall power conversion efficiency of the cell by a factor of five. Finally, this is the first report of a photovoltaic device based onFe 2GeS 4.« less

Effect of Thermal Annealing on the Band GAP and Optical Properties of Chemical Bath Deposited ZnSe Thin Films

NASA Astrophysics Data System (ADS)

Ezema, F. I.; Ekwealor, A. B. C.; Osuji, R. U.

2006-05-01

Zinc selenide (ZnSe) thin films were deposited on glass substrate using the chemical bath deposition method at room temperature from aqueous solutions of zinc sulphate and sodium selenosulfate in which sodium hydroxide was employed as complexing agents. The `as-deposited' ZnSe thin films are red in color and annealed in oven at 473 K for 1 hour and on a hot plate in open air at 333 K for 5 minutes, affecting the morphological and optical properties. Optical properties such as absorption coefficient a and extinction coefficient k, were determined using the absorbance and transmission measurement from Unico UV-2102 PC spectrophotometer, at normal incidence of light in the wavelength range of 200-1000 nm. The films have transmittance in VIS-NIR regions that range between 26 and 87%. From absorbance and transmittance spectra, the band gap energy determined ranged between 1.60 eV and 1.75 for the `as deposited' samples, and the annealed samples exhibited a band gap shift of 0.15 eV. The high transmittance of the films together with its large band gap made them good materials for selective coatings for solar cells.

Experimental studies of thin films deposition by magnetron sputtering method for CIGS solar cell fabrication

NASA Astrophysics Data System (ADS)

Gułkowski, Sławomir; Krawczak, Ewelina

2017-10-01

Among a variety of the thin film solar cell technologies of second generation, copper-indium-gallium-diselenide device (CIGS) with the latest highest lab cell efficiency record of 22.4 % seems to be the most promising for the power generation. This is partly due to the advantages of using low cost films of few microns thick not only as a metallic contacts but also as a main structure of the solar cell consisted of high quality semiconductor layers. This paper reports the experimental studies of the CIGS absorber formation on Soda Lime Glass substrate covered by thin molybdenum film as a back contact layer. All structures were deposited with the use of magnetron sputtering method only. Technological parameters of the deposition process such as deposition power, pressure and deposition time were optimized for each layer of the structure. Mo back contact was examined in terms of resistivity. EDS measurements were carried out to verify stoichiometric composition of CIGS absorber. Thin film of Al was used as a top contact in order to examine the quality of p-n junction. The I-V electrical characteristic of the p-n junction was analysed in terms of solar cell application.

Ultrashort pulse generation in mode-locked erbium-doped fiber lasers with tungsten disulfide saturable absorber

NASA Astrophysics Data System (ADS)

Liu, Mengli; Liu, Wenjun; Pang, Lihui; Teng, Hao; Fang, Shaobo; Wei, Zhiyi

2018-01-01

Tungsten disulfide (WS2), as one of typical transition metal dichalcogenides with the characteristics of strong nonlinear polarization and wide bandgap, has been widely used in such fields as biology and optoelectronics. With the magnetron sputtering technique, the saturable absorber (SA) is prepared by depositing WS2 and Au film on the tapered fiber. The heat elimination and damage threshold can be improved for the WS2 SA with evanescent field interaction. Besides, the Au film is deposited on the surface of the WS2 film to improve their reliability and avoid being oxidized. The fabricated SA has a modulation depth of 14.79%. With this SA, we obtain a relatively stable mode-locked fiber laser with the pulse duration of 288 fs, the repetition rate of 41.4 MHz and the signal to noise ratio of 58 dB.

Ion Beam Assisted Deposition of Thin Epitaxial GaN Films.

PubMed

Rauschenbach, Bernd; Lotnyk, Andriy; Neumann, Lena; Poppitz, David; Gerlach, Jürgen W

2017-06-23

The assistance of thin film deposition with low-energy ion bombardment influences their final properties significantly. Especially, the application of so-called hyperthermal ions (energy <100 eV) is capable to modify the characteristics of the growing film without generating a large number of irradiation induced defects. The nitrogen ion beam assisted molecular beam epitaxy (ion energy <25 eV) is used to deposit GaN thin films on (0001)-oriented 6H-SiC substrates at 700 °C. The films are studied in situ by reflection high energy electron diffraction, ex situ by X-ray diffraction, scanning tunnelling microscopy, and high-resolution transmission electron microscopy. It is demonstrated that the film growth mode can be controlled by varying the ion to atom ratio, where 2D films are characterized by a smooth topography, a high crystalline quality, low biaxial stress, and low defect density. Typical structural defects in the GaN thin films were identified as basal plane stacking faults, low-angle grain boundaries forming between w-GaN and z-GaN and twin boundaries. The misfit strain between the GaN thin films and substrates is relieved by the generation of edge dislocations in the first and second monolayers of GaN thin films and of misfit interfacial dislocations. It can be demonstrated that the low-energy nitrogen ion assisted molecular beam epitaxy is a technique to produce thin GaN films of high crystalline quality.

Aerosol-Assisted Chemical Vapor Deposited Thin Films for Space Photovoltaics

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; McNatt, Jeremiah; Dickman, John E.; Jin, Michael H.-C.; Banger, Kulbinder K.; Kelly, Christopher V.; AquinoGonzalez, Angel R.; Rockett, Angus A.

2006-01-01

Copper indium disulfide thin films were deposited via aerosol-assisted chemical vapor deposition using single source precursors. Processing and post-processing parameters were varied in order to modify morphology, stoichiometry, crystallography, electrical properties, and optical properties in order to optimize device-quality material. Growth at atmospheric pressure in a horizontal hot-wall reactor at 395 C yielded best device films. Placing the susceptor closer to the evaporation zone and flowing a more precursor-rich carrier gas through the reactor yielded shinier, smoother, denser-looking films. Growth of (112)-oriented films yielded more Cu-rich films with fewer secondary phases than growth of (204)/(220)-oriented films. Post-deposition sulfur-vapor annealing enhanced stoichiometry and crystallinity of the films. Photoluminescence studies revealed four major emission bands (1.45, 1.43, 1.37, and 1.32 eV) and a broad band associated with deep defects. The highest device efficiency for an aerosol-assisted chemical vapor deposited cell was 1.03 percent.

Growth and characterization of CdS buffer layers by CBD and MOCVD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morrone, A.A.; Huang, C.; Li, S.S.

1999-03-01

Thin film CdS has been widely used in thin-film photovoltaic devices. The most efficient Cu(In,&hthinsp;Ga)Se{sub 2} (CIGS) solar cells reported to date utilized a thin CdS buffer layer prepared by a reactive solution growth technique known as chemical bath deposition (CBD). Considerable effort has been directed to better understand the role and find a replacement for the CBD CdS process in CIGS-based solar cells. We reported a low temperature ({approximately}150&hthinsp;{degree}C) Metalorganic Chemical Vapor Deposition (MOCVD) CdS thin film buffer layer process for CIGS absorbers. Many prior studies have reported that CBD CdS contains a mixture of crystal structures. Recent investigationsmore » of CBD CdS thin films by ellipsometry suggested a multilayer structure. In this study we compare CdS thin films prepared by CBD and MOCVD and the effects of annealing. TED and XRD are used to characterize the crystal structure, the film microstructure is studied by HRTEM, and the optical properties are studied by Raman and spectrophotometry. All of these characterization techniques reveal superior crystalline film quality for CdS films grown by MOCVD compared to those grown by CBD. Dual Beam Optical Modulation (DBOM) studies showed that the MOCVD and CBD CdS buffer layer processes have nearly the same effect on CIGS absorbers when combined with a cadmium partial electrolyte aqueous dip. {copyright} {ital 1999 American Institute of Physics.}« less

Determination of copper in tap water using solid-phase spectrophotometry

NASA Technical Reports Server (NTRS)

Hill, Carol M.; Street, Kenneth W.; Philipp, Warren H.; Tanner, Stephen P.

1994-01-01

A new application of ion exchange films is presented. The films are used in a simple analytical method of directly determining low concentrations of Cu(2+) in aqueous solutions, in particular, drinking water. The basis for this new test method is the color and absorption intensity of the ion when adsorbed onto the film. The film takes on the characteristic color of the adsorbed cation, which is concentrated on the film by many orders of magnitude. The linear relationship between absorbance (corrected for variations in film thickness) and solution concentration makes the determinations possible. These determinations agree well with flame atomic absorption determinations.

Effect of selenization time on the structural and morphological properties of Cu(In,Ga)Se2 thin films absorber layers using two step growth process

NASA Astrophysics Data System (ADS)

Korir, Peter C.; Dejene, Francis B.

2018-04-01

In this work two step growth process was used to prepare Cu(In, Ga)Se2 thin film for solar cell applications. The first step involves deposition of Cu-In-Ga precursor films followed by the selenization process under vacuum using elemental selenium vapor to form Cu(In,Ga)Se2 film. The growth process was done at a fixed temperature of 515 °C for 45, 60 and 90 min to control film thickness and gallium incorporation into the absorber layer film. The X-ray diffraction (XRD) pattern confirms single-phase Cu(In,Ga)Se2 film for all the three samples and no secondary phases were observed. A shift in the diffraction peaks to higher 2θ (2 theta) values is observed for the thin films compared to that of pure CuInSe2. The surface morphology of the resulting film grown for 60 min was characterized by the presence of uniform large grain size particles, which are typical for device quality material. Photoluminescence spectra show the shifting of emission peaks to higher energies for longer duration of selenization attributed to the incorporation of more gallium into the CuInSe2 crystal structure. Electron probe microanalysis (EPMA) revealed a uniform distribution of the elements through the surface of the film. The elemental ratio of Cu/(In + Ga) and Se/Cu + In + Ga strongly depends on the selenization time. The Cu/In + Ga ratio for the 60 min film is 0.88 which is in the range of the values (0.75-0.98) for best solar cell device performances.

Biological preconcentrator

DOEpatents

Manginell, Ronald P [Albuquerque, NM; Bunker, Bruce C [Albuquerque, NM; Huber, Dale L [Albuquerque, NM

2008-09-09

A biological preconcentrator comprises a stimulus-responsive active film on a stimulus-producing microfabricated platform. The active film can comprise a thermally switchable polymer film that can be used to selectively absorb and desorb proteins from a protein mixture. The biological microfabricated platform can comprise a thin membrane suspended on a substrate with an integral resistive heater and/or thermoelectric cooler for thermal switching of the active polymer film disposed on the membrane. The active polymer film can comprise hydrogel-like polymers, such as poly(ethylene oxide) or poly(n-isopropylacrylamide), that are tethered to the membrane. The biological preconcentrator can be fabricated with semiconductor materials and technologies.

Chain Conformation and Dynamics in Spin-Assisted Weak Polyelectrolyte Multilayers

DOE PAGES

Zhuk, Aliaksandr; Selin, Victor; Zhuk, Iryna; ...

2015-03-13

In this paper, we report on the effect of the deposition technique on film layering, stability, and chain mobility in weak polyelectrolyte layer-by-layer (LbL) films. Ellipsometry and neutron reflectometry (NR) showed that shear forces arising during spin-assisted assembly lead to smaller amounts of adsorbed polyelectrolytes within LbL films, result in a higher degree of internal film order, and dramatically improve stability of assemblies in salt solutions as compared to dip-assisted LbL assemblies. The underlying flattening of polyelectrolyte chains in spin-assisted LbL films was also revealed as an increase in ionization degree of the assembled weak polyelectrolytes. As demonstrated by fluorescencemore » recovery after photobleaching (FRAP), strong binding between spin-deposited polyelectrolytes results in a significant slowdown of chain diffusion in salt solutions as compared to dip-deposited films. Moreover, salt-induced chain intermixing in the direction perpendicular to the substrate is largely inhibited in spin-deposited films, resulting in only subdiffusional (<2 Å) chain displacements even after 200 h exposure to 1 M NaCl solutions. Finally, this persistence of polyelectrolyte layering has important ramifications for multistage drug delivery and optical applications of LbL assemblies.« less

Combinatorial chemical bath deposition of CdS contacts for chalcogenide photovoltaics

DOE PAGES

Mokurala, Krishnaiah; Baranowski, Lauryn L.; de Souza Lucas, Francisco W.; ...

2016-08-01

Contact layers play an important role in thin film solar cells, but new material development and optimization of its thickness is usually a long and tedious process. A high-throughput experimental approach has been used to accelerate the rate of research in photovoltaic (PV) light absorbers and transparent conductive electrodes, however the combinatorial research on contact layers is less common. Here, we report on the chemical bath deposition (CBD) of CdS thin films by combinatorial dip coating technique and apply these contact layers to Cu(In,Ga)Se 2 (CIGSe) and Cu 2ZnSnSe 4 (CZTSe) light absorbers in PV devices. Combinatorial thickness steps ofmore » CdS thin films were achieved by removal of the substrate from the chemical bath, at regular intervals of time, and in equal distance increments. The trends in the photoconversion efficiency and in the spectral response of the PV devices as a function of thickness of CdS contacts were explained with the help of optical and morphological characterization of the CdS thin films. The maximum PV efficiency achieved for the combinatorial dip-coating CBD was similar to that for the PV devices processed using conventional CBD. Finally, the results of this study lead to the conclusion that combinatorial dip-coating can be used to accelerate the optimization of PV device performance of CdS and other candidate contact layers for a wide range of emerging absorbers.« less

Controlled-reflectance surfaces with film-coupled colloidal nanoantennas.

PubMed

Moreau, Antoine; Ciracì, Cristian; Mock, Jack J; Hill, Ryan T; Wang, Qiang; Wiley, Benjamin J; Chilkoti, Ashutosh; Smith, David R

2012-12-06

Efficient and tunable absorption is essential for a variety of applications, such as designing controlled-emissivity surfaces for thermophotovoltaic devices, tailoring an infrared spectrum for controlled thermal dissipation and producing detector elements for imaging. Metamaterials based on metallic elements are particularly efficient as absorbing media, because both the electrical and the magnetic properties of a metamaterial can be tuned by structured design. So far, metamaterial absorbers in the infrared or visible range have been fabricated using lithographically patterned metallic structures, making them inherently difficult to produce over large areas and hence reducing their applicability. Here we demonstrate a simple method to create a metamaterial absorber by randomly adsorbing chemically synthesized silver nanocubes onto a nanoscale-thick polymer spacer layer on a gold film, making no effort to control the spatial arrangement of the cubes on the film. We show that the film-coupled nanocubes provide a reflectance spectrum that can be tailored by varying the geometry (the size of the cubes and/or the thickness of the spacer). Each nanocube is the optical analogue of a grounded patch antenna, with a nearly identical local field structure that is modified by the plasmonic response of the metal's dielectric function, and with an anomalously large absorption efficiency that can be partly attributed to an interferometric effect. The absorptivity of large surface areas can be controlled using this method, at scales out of reach of lithographic approaches (such as electron-beam lithography) that are otherwise required to manipulate matter on the nanoscale.

Broadband polarization-independent and low-profile optically transparent metamaterial absorber

NASA Astrophysics Data System (ADS)

Li, Long; Xi, Rui; Liu, Haixia; Lv, Zhiyong

2018-05-01

A transparent metamaterial absorber with simultaneously high optical transparency and broadband microwave absorption is presented in this paper. Consisting of a two-layer soda-lime glass substrate and three-layer patch-shaped indium tin oxide (ITO) films, the proposed absorber has advantages of broadband absorption with an absorptivity higher than 85% in the range from 6.1 to 22.1 GHz, good polarization insensitiveness, a high transparency, a low profile, and wide-incident-angle stability. A prototype of the proposed absorber is fabricated and experimentally measured to demonstrate its excellent performance. The measured results agree well with the theoretical design and numerical simulations.

Tunable and multi-channel perfect absorber based on graphene at mid-infrared region

NASA Astrophysics Data System (ADS)

Meng, HaiYu; Xue, XiongXiong; Lin, Qi; Liu, GuiDong; Zhai, Xiang; Wang, LingLing

2018-05-01

A tunable, multi-channel plasmonic perfect absorber based on graphene is proposed. Simulated results reveal that the resonant wavelength can be effectively tuned in many ways (by changing the Fermi energy of graphene, radius of Si, or air gap between the Si and the graphene film). Furthermore, the multi-channel perfect absorber is obtained by changing the period of the system. Specifically, a high absorption is obtained by using a multilayer Bragg mirror in place of the metallic plate. We believe that such an absorber may have potential applications for multi-channel photodetectors, frequency selection, and electromagnetic-wave energy storage.

III-V semiconductor resonators: A new strategy for broadband light perfect absorbers

NASA Astrophysics Data System (ADS)

Liu, Xiaoshan; Chen, Jian; Liu, Jiasong; Huang, Zhenping; Yu, Meidong; Pan, Pingping; Liu, Zhengqi

2017-11-01

Broadband light perfect absorbers (BPAs) are desirable for applications in numerous optoelectronics devices. In this work, a semiconductor-based broadband light perfect absorber (S-BPA) has been numerically demonstrated by utilizing plasmonlike resonances of high-index semiconductor resonators. A maximal absorption of 99.7% is observed in the near-infrared region. By taking the absorption above 80% into account, the spectral bandwidth reaches 340 nm. The absorption properties mainly originate from the optical cavity modes induced by the cylinder resonators and ultrathin semiconductor film. These optical properties and simple structural features can maintain the absorber platform with wide applications in semiconductor optoelectronics.

TiAlN/TiAlON/Si{sub 3}N{sub 4} tandem absorber for high temperature solar selective applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barshilia, Harish C.; Selvakumar, N.; Rajam, K. S.

2006-11-06

A tandem absorber of TiAlN/TiAlON/Si{sub 3}N{sub 4} is prepared using a magnetron sputtering process. The graded composition of the individual component layers of the tandem absorber produces a film with a refractive index increasing from the surface to the substrate, which exhibits a high absorptance (0.95) and a low emittance (0.07). The tandem absorber is stable in air up to 600 deg. C for 2 h, indicating its importance for high temperature solar selective applications. The thermal stability of the tandem absorber is attributed to high oxidation resistance and microstructural stability of the component materials at higher temperatures.

Repair of orbital floor fractures with absorbable gelatin film.

PubMed

Mermer, R W; Orban, R E

1995-01-01

Many materials have been utilized for the repair of orbital floor fractures. Absorbable gelatin film is a bioabsorbable sheeting material that is manufactured from denatured collagen. This material is appropriate for the repair of smaller orbital floor defects (5 mm or less) and trapdoor-type fractures; it is used with larger defects as an interpositional graft material between the periorbital tissues and as an orbital floor reconstruction plate or mesh. Sixteen cases consisting of both types of defects were retrospectively examined clinically and radiographically. Satisfactory results were obtained in all of these cases, including no adverse ocular signs or implant rejection, good facial form, good function, and acceptable postoperative radiography results.

Laser interferometry for the determination of thickness distributions of low absorbing films and their spatial and thickness resolutions.

PubMed

Mishima, T; Kao, K C

1982-03-15

New laser interferometry has been developed, based on the principle that a 2-D fringe pattern can be produced by interference of spatially coherent light beams. To avoid the effect of reflection from the back surface of the substrate, the Brewster angle of incidence is adopted; to suppress the effect of diffraction, a lens or a lens system is used. This laser interferometry is an efficient nondestructive technique for the determination of thickness distributions or uniformities of low absorbing films on transparent substrates over a large area without involving laborious computations. The limitation of spatial resolution, thickness resolution, and visibility of fringes is fully analyzed.

Modulated optical phase conjugation in rhodamine 110 doped boric acid glass saturable absorber thin films

NASA Astrophysics Data System (ADS)

Sharma, Ramesh C.; Waigh, Thomas A.; Singh, Jagdish P.

2008-03-01

The optical phase conjugation signal in nearly nondegenerate four wave mixing was studied using a rhodamine 110 doped boric acid glass saturable absorber nonlinear medium. We have demonstrated a narrow band optical filter (2.56±0.15Hz) using an optical phase conjugation signal in the frequency modulation of a weak probe beam in the presence of two strong counterpropagating pump beams in rhodamine 110 doped boric acid glass thin films (10-4m). Both the pump beams and the probe beam are at a wavelength of 488nm (continuous-wave Ar+ laser). The probe beam frequency was detuned with a ramp signal using a piezoelectric transducer mirror.

Two-dimensional turning of thermal flux from normal to lateral propagation in thin metal film irradiated by femtosecond laser pulse

NASA Astrophysics Data System (ADS)

Shepelev, V. V.; Inogamov, N. A.

2018-01-01

There are various geometrical variants of laser illumination and target design. Important direction of investigations is connected with tightly focused action (spot size may be less than micron) onto a thin metal film: thickness of a film is just few skin-layer depths. Duration of a pulse is τ L ˜ 0.1 ps. In these conditions energy absorbed in a skin layer first propagates normally to a surface: gradient ∂Te /∂x dominates, here and below x and y are normal and lateral directions. This process in 1-2 ps homogenizes electron temperature T e along thickness of a film. We consider conditions when a film or is supported by weakly conducting substrate, or is free standing. Therefore all absorbed energy is confined inside the film. At the next stage the internal energy begin to flow along the lateral direction—thus direction of energy expansion is changed from x to y because of the heat non-penetrating boundary condition imposed on the rear-side of the film. At the short two-temperature stage of lateral expansion the thermal conductivity κ is high. After that electron and ion temperatures equilibrates and later on the heat propagates with usual value of κ. Lateral expansion cools down the hot spot on long time scales and finally the molten spot recrystallizes. Two-dimensional approach allows us to consider all these stages from propagation in x direction (normal to a film) to propagation in y direction (along a film).

Jet impact on a soap film

NASA Astrophysics Data System (ADS)

Kirstetter, Geoffroy; Raufaste, Christophe; Celestini, Franck

2012-09-01

We experimentally investigate the impact of a liquid jet on a soap film. We observe that the jet never breaks the film and that two qualitatively different steady regimes may occur. The first one is a refractionlike behavior obtained at small incidence angles when the jet crosses the film and is deflected by the film-jet interaction. For larger incidence angles, the jet is absorbed by the film, giving rise to a new class of flows in which the jet undulates along the film with a characteristic wavelength. Besides its fundamental interest, this paper presents a different way to guide a micrometric flow of liquid in the inertial regime and to probe foam stability submitted to violent perturbations at the soap film scale.

Jet impact on a soap film.

PubMed

Kirstetter, Geoffroy; Raufaste, Christophe; Celestini, Franck

2012-09-01

We experimentally investigate the impact of a liquid jet on a soap film. We observe that the jet never breaks the film and that two qualitatively different steady regimes may occur. The first one is a refractionlike behavior obtained at small incidence angles when the jet crosses the film and is deflected by the film-jet interaction. For larger incidence angles, the jet is absorbed by the film, giving rise to a new class of flows in which the jet undulates along the film with a characteristic wavelength. Besides its fundamental interest, this paper presents a different way to guide a micrometric flow of liquid in the inertial regime and to probe foam stability submitted to violent perturbations at the soap film scale.

Method for the manufacture of phase shifting masks for EUV lithography

DOEpatents

Stearns, Daniel G.; Sweeney, Donald W.; Mirkarimi, Paul B.; Barty, Anton

2006-04-04

A method for fabricating an EUV phase shift mask is provided that includes a substrate upon which is deposited a thin film multilayer coating that has a complex-valued reflectance. An absorber layer or a buffer layer is attached onto the thin film multilayer, and the thickness of the thin film multilayer coating is altered to introduce a direct modulation in the complex-valued reflectance to produce phase shifting features.

Effects of thermochemical treatment on CuSbS 2 photovoltaic absorber quality and solar cell reproducibility

DOE PAGES

de Souza Lucas, Francisco Willian; Welch, Adam W.; Baranowski, Lauryn L.; ...

2016-08-01

CuSbS 2 is a promising nontoxic and earth-abundant photovoltaic absorber that is chemically simpler than the widely studied Cu 2ZnSnS 4. However, CuSbS 2 photovoltaic (PV) devices currently have relatively low efficiency and poor reproducibility, often due to suboptimal material quality and insufficient optoelectronic properties. To address these issues, here we develop a thermochemical treatment (TT) for CuSbS 2 thin films, which consists of annealing in Sb 2S 3 vapor followed by a selective KOH surface chemical etch. The annealed CuSbS 2 films show improved structural quality and optoelectronic properties, such as stronger band-edge photoluminescence and longer photoexcited carrier lifetime.more » These improvements also lead to more reproducible CuSbS 2 PV devices, with performance currently limited by a large cliff-type interface band offset with CdS contact. Altogether, these results point to the potential avenues to further increase the performance of CuSbS 2 thin film solar cell, and the findings can be transferred to other thin film photovoltaic technologies.« less

Tunable broadband near-infrared absorber based on ultrathin phase-change material

NASA Astrophysics Data System (ADS)

Hu, Er-Tao; Gu, Tong; Guo, Shuai; Zang, Kai-Yan; Tu, Hua-Tian; Yu, Ke-Han; Wei, Wei; Zheng, Yu-Xiang; Wang, Song-You; Zhang, Rong-Jun; Lee, Young-Pak; Chen, Liang-Yao

2017-11-01

In this work, a tunable broadband near-infrared light absorber was designed and fabricated with a simple and lithography free approach by introducing an ultrathin phase-change material Ge2Sb2Te5 (GST) layer into the metal-dielectric multilayered film structure with the structure parameters as that: SiO2 (72.7 nm)/Ge2Sb2Te5 (6.0 nm)/SiO2 (70.2 nm)/Cu (>100.0 nm). The film structure exhibits a modulation depth of ∼72.6% and an extinction ratio of ∼8.8 dB at the wavelength of 1410 nm. The high light absorption (95%) of the proposed film structure at the wavelength of 450 nm in both of the amorphous and crystalline phase of GST, indicates that the intensity of the reflectance in the infrared region can be rapidly tuned by the blue laser pulses. The proposed planar layered film structure with layer thickness as the only controllable parameter and large reflectivity tuning range shows the potential for practical applications in near-infrared light modulation and absorption.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isfahani, RN; Moghaddam, S

An experimental study on absorption characteristics of water vapor into a thin lithium bromide (LiBr) solution flow is presented. The LiBr solution flow is constrained between a superhydrophobic vapor permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure, cooling surface temperature, solution film thickness, and solution flow velocity on the absorption rate are studied. An absorption rate of approximately 0.006 kg/m(2) s was measured at amore » LiBr solution channel thickness and flow velocity of 100 mu m and 5 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the test conditions of this study. It was demonstrated that decreasing the solution film thickness and increasing the solution velocity enhance the absorption rate. The high absorption rate and the inherently compact form of the proposed,absorber facilitate development of compact small-scale waste heat or solar-thermal driven cooling systems. Published by Elsevier Ltd.« less

(abstract) Optical Scattering and Surface Microroughness of Ion Beam Deposited Au and Pt Thin Films

NASA Technical Reports Server (NTRS)

Al-Jumaily, Ghanim A.; Raouf, Nasrat A.; Edlou, Samad M.; Simons, John C.

1994-01-01

Thin films of gold and platinum have been deposited onto superpolished fused silica substrates using thermal evaporation, ion assisted deposition (IAD), and ion assisted sputtering. The influence of ion beam flux, thin film material, and deposition rate on the films microroughness have been investigated. Short range surface microroughness of the films has been examined using scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Long range surface microroughness has been characterized using an angle resolved optical scatterometer. Results indicate that ion beam deposited coatings have improved microstructure over thermally evaporated films.

Dendritic-metasurface-based flexible broadband microwave absorbers

NASA Astrophysics Data System (ADS)

Wang, Mei; Weng, Bin; Zhao, Jing; Zhao, Xiaopeng

2017-06-01

Based on the dendritic metasurface model, a type of flexible and lightweight microwave absorber (MA) comprising resistance film array with dendritic slot (RFADS), dielectric material, and metal plate is proposed. A broadband absorptivity of >80% is obtained both from simulation and experiment at frequency ranges of 3.0-9.2 and 3.2-9.00 GHz, respectively. And the thickness of MA is 5 mm, which is only 0.05λ _{low}, or 0.15λ _ {high}, where the λ _{low} and the λ _{high} are the beginning and the end of the working frequency. By combining this metasurface-based MA with the dendritic-resistance-film-based microwave metasurface absorber (MMA), we designed a broadband MMA. The simulations and experiments showed that this kind of MMA can absorb the radiation effectively at a wide frequency range 4.5-17.5 GHz. And the thickness of this combined MMA is 4 mm. All the structures showed their insensitivity to the incident angle (0°-40°) and the polarization of the incident wave because of their structural symmetry. In addition, the small thickness, low apparent density, and flexibility made those structures possess the advantages of being applied in microwave stealth and radar cross-section (RCS) reduction.

Precursors for the polymer-assisted deposition of films

DOEpatents

McCleskey, Thomas M.; Burrell, Anthony K.; Jia, Quanxi; Lin, Yuan

2013-09-10

A polymer assisted deposition process for deposition of metal oxide films is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures to yield metal oxide films. Such films can be epitaxial in structure and can be of optical quality. The process can be organic solvent-free.

Synthesis and characterization of transparent conductive zinc oxide thin films by sol-gel spin coating method

NASA Astrophysics Data System (ADS)

Winarski, David

Zinc oxide has been given much attention recently as it is promising for various semiconductor device applications. ZnO has a direct band gap of 3.3 eV, high exciton binding energy of 60 meV and can exist in various bulk powder and thin film forms for different applications. ZnO is naturally n-type with various structural defects, which sparks further investigation into the material properties. Although there are many potential applications for this ZnO, an overall lack of understand and control of intrinsic defects has proven difficult to obtain consistent, repeatable results. This work studies both synthesis and characterization of zinc oxide in an effort to produce high quality transparent conductive oxides. The sol-gel spin coating method was used to obtain highly transparent ZnO thin films with high UV absorbance. This research develops a new more consistent method for synthesis of these thin films, providing insight for maintaining quality control for each step in the procedure. A sol-gel spin coating technique is optimized, yielding highly transparent polycrystalline ZnO thin films with tunable electrical properties. Annealing treatment in hydrogen and zinc atmospheres is researched in an effort to increase electrical conductivity and better understand intrinsic properties of the material. These treatment have shown significant effects on the properties of ZnO. Characterization of doped and undoped ZnO synthesized by the sol-gel spin coating method was carried out using scanning electron microscopy, UV-Visible range absorbance, X-ray diffraction, and the Hall Effect. Treatment in hydrogen shows an overall decrease in the number of crystal phases and visible absorbance while zinc seems to have the opposite effect. The Hall Effect has shown that both annealing environments increase the n-type conductivity, yielding a ZnO thin film with a carrier concentration as high as 3.001 x 1021 cm-3.

Reactive decontamination of absorbing thin film polymer coatings: model development and parameter determination

NASA Astrophysics Data System (ADS)

Varady, Mark; Mantooth, Brent; Pearl, Thomas; Willis, Matthew

2014-03-01

A continuum model of reactive decontamination in absorbing polymeric thin film substrates exposed to the chemical warfare agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (known as VX) was developed to assess the performance of various decontaminants. Experiments were performed in conjunction with an inverse analysis method to obtain the necessary model parameters. The experiments involved contaminating a substrate with a fixed VX exposure, applying a decontaminant, followed by a time-resolved, liquid phase extraction of the absorbing substrate to measure the residual contaminant by chromatography. Decontamination model parameters were uniquely determined using the Levenberg-Marquardt nonlinear least squares fitting technique to best fit the experimental time evolution of extracted mass. The model was implemented numerically in both a 2D axisymmetric finite element program and a 1D finite difference code, and it was found that the more computationally efficient 1D implementation was sufficiently accurate. The resulting decontamination model provides an accurate quantification of contaminant concentration profile in the material, which is necessary to assess exposure hazards.

Polymers in solar energy utilization

NASA Technical Reports Server (NTRS)

Liang, R. H.; Coulter, D. R.; Dao, C.; Gupta, A.

1983-01-01

A laser photoacoustic technique (LPAT) has been verified for performing accelerated life testing of outdoor photooxidation of polymeric materials used in solar energy applications. Samples of the material under test are placed in a chamber with a sensitive microphone, then exposed to chopped laser radiation. The sample absorbs the light and converts it to heat by a nonradiative deexcitation process, thereby reducing pressure fluctuations within the cell. The acoustic signal detected by the microphone is directly proportional to the amount of light absorbed by the specimen. Tests were performed with samples of ethylene/methylacrylate copolymer (EMA) reprecipitated from hot cyclohexane, compressed, and molded into thin (25-50 microns) films. The films were exposed outdoors and sampled by LPAT weekly. The linearity of the light absorbed with respect to the acoustic signal was verified.Correlations were established between the photoacoustic behavior of the materials aged outdoors and the same kinds of samples cooled and heated in a controlled environment reactor. The reactor tests were validated for predicting outdoor exosures up to 55 days.

Study of earth abundant tco and absorber materials for photovoltaic applications

NASA Astrophysics Data System (ADS)

Prabhakar, Tejas

In order to make photovoltaic power generation a sustainable venture, it is necessary to use cost-effective materials in the manufacture of solar cells. In this regard, AZO (Aluminum doped Zinc Oxide) and CZTS (Copper Zinc Tin Sulfide) have been studied for their application in thin film solar cells. While AZO is a transparent conducting oxide, CZTS is a photovoltaic absorber. Both AZO and CZTS consist of earth abundant elements and are non-toxic in nature. Highly transparent and conductive AZO thin films were grown using RF sputtering. The influence of deposition parameters such as working pressure, RF power, substrate temperature and flow rate on the film characteristics was investigated. The as-grown films had a high degree of preferred orientation along the (002) direction which enhanced at lower working pressures, higher RF powers and lower substrate temperatures. Williamson-Hall analysis on the films revealed that as the working pressure was increased, the nature of stress and strain gradually changed from being compressive to tensile. The fall in optical transmission of the films was a consequence of free carrier absorption resulting from enhanced carrier density due to incorporation of Al atoms or oxygen vacancies. The optical and electrical properties of the films were described well by the Burstein-Moss effect. CZTS absorber layers were grown using ultrasonic spray pyrolysis at a deposition temperature of 350 C and subsequently annealed in a sulfurization furnace. Measurements from XRD and Raman spectra confirmed the presence of pure single phase Cu2ZnSnS4. Texture analysis of as-deposited and annealed CZTS films indicated that the (112) plane which is characteristic of the kesterite phase was preferred. The grain size increased from 50 nm to 100 nm on conducting post-deposition annealing. CZTS films with stoichiometric composition yielded a band gap of 1.5 eV, which is optimal for solar energy conversion. The variation of tin in the film changed its resistivity by several orders of magnitude and subsequently the tin free ternary chalcogenide Cu2ZnS2 having very low resistivity was obtained. By carefully optimization of concentrations of tin, zinc and copper, a zinc-rich/tin-rich/copper-poor composition was found to be most suitable for solar cell applications. Etching of CZTS films using KCN solution reduced their resistivity, possibly due to the elimination of binary copper sulfide phases. CZTS solar cells were fabricated both in the substrate and superstrate configurations.

Dosimetry for Small Fields in Stereotactic Radiosurgery Using Gafchromic MD-V2-55 Film, TLD-100 and Alanine Dosimeters

PubMed Central

Massillon-JL, Guerda; Cueva-Prócel, Diego; Díaz-Aguirre, Porfirio; Rodríguez-Ponce, Miguel; Herrera-Martínez, Flor

2013-01-01

This work investigated the suitability of passive dosimeters for reference dosimetry in small fields with acceptable accuracy. Absorbed dose to water rate was determined in nine small radiation fields with diameters between 4 and 35 mm in a Leksell Gamma Knife (LGK) and a modified linear accelerator (linac) for stereotactic radiosurgery treatments. Measurements were made using Gafchromic film (MD-V2-55), alanine and thermoluminescent (TLD-100) dosimeters and compared with conventional dosimetry systems. Detectors were calibrated in terms of absorbed dose to water in 60Co gamma-ray and 6 MV x-ray reference (10×10 cm2) fields using an ionization chamber calibrated at a standards laboratory. Absorbed dose to water rate computed with MD-V2-55 was higher than that obtained with the others dosimeters, possibly due to a smaller volume averaging effect. Ratio between the dose-rates determined with each dosimeter and those obtained with the film was evaluated for both treatment modalities. For the LGK, the ratio decreased as the dosimeter size increased and remained constant for collimator diameters larger than 8 mm. The same behaviour was observed for the linac and the ratio increased with field size, independent of the dosimeter used. These behaviours could be explained as an averaging volume effect due to dose gradient and lack of electronic equilibrium. Evaluation of the output factors for the LGK collimators indicated that, even when agreement was observed between Monte Carlo simulation and measurements with different dosimeters, this does not warrant that the absorbed dose to water rate in the field was properly known and thus, investigation of the reference dosimetry should be an important issue. These results indicated that alanine dosimeter provides a high degree of accuracy but cannot be used in fields smaller than 20 mm diameter. Gafchromic film can be considered as a suitable methodology for reference dosimetry. TLD dosimeters are not appropriate in fields smaller than 10 mm diameters. PMID:23671677

Light trapping and electrical transport in thin-film solar cells with randomly rough textures

NASA Astrophysics Data System (ADS)

Kowalczewski, Piotr; Bozzola, Angelo; Liscidini, Marco; Claudio Andreani, Lucio

2014-05-01

Using rigorous electro-optical calculations, we predict a significant efficiency enhancement in thin-film crystalline silicon (c-Si) solar cells with rough interfaces. We show that an optimized rough texture allows one to reach the Lambertian limit of absorption in a wide absorber thickness range from 1 to 100 μm. The improvement of efficiency due to the roughness is particularly substantial for thin cells, for which light trapping is crucial. We consider Auger, Shockley-Read-Hall (SRH), and surface recombination, quantifying the importance of specific loss mechanisms. When the cell performance is limited by intrinsic Auger recombination, the efficiency of 24.4% corresponding to the wafer-based PERL cell can be achieved even if the absorber thickness is reduced from 260 to 10 μm. For cells with material imperfections, defect-based SRH recombination contributes to the opposite trends of short-circuit current and open-circuit voltage as a function of the absorber thickness. By investigating a wide range of SRH parameters, we determine an optimal absorber thickness as a function of material quality. Finally, we show that the efficiency enhancement in textured cells persists also in the presence of surface recombination. Indeed, in our design the efficiency is limited by recombination at the rear (silicon absorber/back reflector) interface, and therefore it is possible to engineer the front surface to a large extent without compromising on efficiency.

Growth of oriented polycrystalline α-HgI 2 films by ultrasonic-wave-assisted physical vapor deposition

NASA Astrophysics Data System (ADS)

Yang, Weiguang; Nie, Lei; Li, Dongmei; Wang, Yali; Zhou, Jie; Ma, Lei; Wang, Zhenhua; Shi, Weimin

2011-06-01

Polycrystalline α-HgI 2 thick films have been grown on ITO-coated glass substrates using ultrasonic-wave-assisted vapor phase deposition (UWAVPD) with the different source temperatures and ultrasonic frequencies. The influence of the assisted ultrasonic wave and source temperature on the structural and electrical properties of the polycrystalline α-HgI 2 films is investigated. It is found that the assisted ultrasonic wave plays an important role in the improvement of the structural and electrical properties. An uniformly oriented polycrystalline α-HgI 2 film with clear facets and narrow size distribution can be obtained at the source temperature of 80 °C under the assistance of 59 KHz ultrasonic frequency with the ultrasonic power of 200 W, which has the lowest value of ρ=2.2×10 12 Ω cm for E-field parallel to c-axis, approaching to that of high quality α-HgI 2 single crystals (4.0×10 12 Ω cm).

Ultrafast and ultrasensitive hydrogen sensors based on self-assembly monolayer promoted 2-dimensional palladium nanoclusters

DOEpatents

Xu, Tao; Zach, Michael P.; Xiao, Zhili

2007-02-06

A device and method of making same. The device or hydrogen detector has a non-conducting substrate with a metal film capable of absorbing hydrogen to form a stable metal hydride. The metal film is being on the threshold of percolation and is connected to mechanism for sensing a change in electrical resistance in response to the presence of hydrogen in contact with the metal film which causes an increase in conductivity.

Ultrafast and ultrasensitive hydrogen sensors based on self-assembly monolayer promoted 2-dimensional palladium nanoclusters

DOEpatents

Xu, Tao [Darien, IL; Zach, Michael P [Darien, IL; Xiao, Zhili [Naperville, IL

2008-06-24

A device and method of making same. The device or hydrogen detector has a non-conducting substrate with a metal film capable of absorbing hydrogen to form a stable metal hydride. The metal film is on the threshold of percolation and is connected to mechanism for sensing a change in electrical resistance in response to the presence of hydrogen in contact with the metal film which causes an increase in conductivity.

Evaluation of tensile properties and water absortion of cassava starch film

NASA Astrophysics Data System (ADS)

Walster, R. Justin; Rozyanty, A. R.; Kahar, A. W. M.; Musa, L.; Shahnaz, S. B. S.

2017-09-01

Casava Starch film was prepared by casting method with different percentage of glycerol (0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5%) as plasticizer. The effect of glycerol content in starch film on mechanical and water absorption properties was studied. Results shows that the increase of glycerol content in cassava starch film had decrease the tensile strength, tensile modulus and increase the elongation of break properties. The result of water absorbency tended to increase for starch film with higher percentage of glycerol content. The incorporation of glycerol in cassava starch film had increase the water absorption ability due to increase of hydroxyl content contributed by glycerol.

Synthesis and characterisation of co-evaporated tin sulphide thin films

NASA Astrophysics Data System (ADS)

Koteeswara Reddy, N.; Ramesh, K.; Ganesan, R.; Ramakrishna Reddy, K. T.; Gunasekhar, K. R.; Gopal, E. S. R.

2006-04-01

Tin sulphide films were grown at different substrate temperatures by a thermal co-evaporation technique. The crystallinity of the films was evaluated from X-ray diffraction studies. Single-phase SnS films showed a strong (040) orientation with an orthorhombic crystal structure and a grain size of 0.12 μm. The films showed an electrical resistivity of 6.1 Ω cm with an activation energy of 0.26 eV. These films exhibited an optical band gap of 1.37 eV and had a high optical absorption coefficient (>104 cm-1) above the band-gap energy. The results obtained were analysed to evaluate the potentiality of the co-evaporated SnS films as an absorber layer in solar photovoltaic devices.

Antenna-coupled transition-edge hot-electron microbolometers

NASA Astrophysics Data System (ADS)

Ali, Shafinaz; Timbie, Peter T.; Malu, Siddharth; McCammon, Dan; Nelms, Kari L.; Pathak, Rashmi; van der Weide, Daniel W.; Allen, Christine A.; Abrahams, J.; Chervenak, James A.; Hsieh, Wen-Ting; Miller, Timothy M.; Moseley, S. H., Jr.; Stevenson, Thomas R.; Wollack, Edward J.

2004-10-01

We are developing a new type of detector for observational cosmology and astrophysical research. Incoming radiation from the sky is coupled to a superconducting microstrip transmission line that terminates in a thin film absorber. At sub-Kelvin temperature, the thermal isolation between the electrons and the lattice makes it possible for the electrons in the small absorber (100's of cubic micro-meter) and superconducting bilayer (Transition Edge Sensor) to heat up by the radiation absorbed by the electrons of the normal absorbing layer. We call this detector a Transition-edge Hot-electron Micro-bolometer (THM). THMs can be fabricated by photo lithography, so it is relatively easy to make matched detectors for a large focal plane array telescope. We report on the thermal properties of Mo/Au THMs with Bi/Au absorbers.

The Effective Audio-Visual Program in Foreign Language and Literature Studies.

ERIC Educational Resources Information Center

Lawton, Ben

Foreign language teachers should exploit the American affinity for television and movies by using foreign language feature films and shorts in the classroom. Social and political history and literary trends illustrated in the films may be discussed and absorbed along with the language. The author teaches such a course in the Department of Italian…

Theory of Coherent Perfect Absorption (CPA) applied to the layered polymer laser

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; Andrews, James; Mao, Guilin

2010-10-01

Coherent perfect absorption (CPA) is a situation in which counterpropagating pump beams can be adjusted so that both beams are completely absorbed by the system. Using theory we delineate the conditions under which a CPA condition can be achieved in real polymeric laser films and remark on CPA's utility for enhancing these films utility.

Effect of Argon/Oxygen Flow Rate Ratios on DC Magnetron Sputtered Nano Crystalline Zirconium Titanate Thin Films

NASA Astrophysics Data System (ADS)

Rani, D. Jhansi; Kumar, A. GuruSampath; Sarmash, T. Sofi; Chandra Babu Naidu, K.; Maddaiah, M.; Rao, T. Subba

2016-06-01

High transmitting, non absorbent, nano crystalline zirconium titanate (ZT) thin films suitable for anti reflection coatings (ARC) were deposited on to glass substrates by direct current (DC) magnetron reactive sputtering technique, under distinct Argon to Oxygen (Ar/O2) gas flow rate ratios of 31/1, 30/2, 29/3 and 28/4, with a net gas flow (Ar + O2) of 32sccm, at an optimum substrate temperature of 250°C. The influence of the gas mixture ratio on the film properties has been investigated by employing x-ray diffraction (XRD), ultra violet visible (UV-vis) spectroscopy, atomic force microscopy (AFM), energy dispersive x-ray analysis (EDX) and four point probe methods. The films showed a predominant peak at 30.85° with (111) orientation. The crystallite size reduced from 22.94 nm to 13.5 nm and the surface roughness increased from 11.53 nm to 50.58 nm with increase in oxygen content respectively. The films deposited at 31/1 and 30/2 showed almost similar chemical composition. Increased oxygen content results an increase in electrical resistivity from 3.59 × 103 to 2.1 × 106 Ωm. The film deposited at Ar/O2 of 28/4 exhibited higher average optical transmittance of 91%, but its refractive index is higher than that of what is required for ARC. The films deposited at 31/1 and 30/2 of Ar/O2 possess higher transmittance (low absorbance) apart from suitable refractive index. Thus, these films are preferable candidates for ARC.

Investigation of Surface Sulfurization in CuIn1-x Gax S2-y Sey Thin Films by Using Kelvin Probe Force Microscopy.

PubMed

Kim, Haeri; Park, Se Jin; Kim, Byungwoo; Hwang, Yun Jeong; Min, Byoung Koun

2018-02-05

CuIn 1-x Ga x S 2-y Se y (CIGSSe) thin films have attracted a great deal of attention as promising absorbing materials for solar cell applications, owing to their favorable optical properties (e.g. a direct band gap and high absorption coefficients) and stable structure. Many studies have sought to improve the efficiency of solar cells using these films, and it has been found that surface modification through post-heat treatment can lead to surface passivation of surface defects and a subsequent increase in efficiency. The surface properties of solution-processed CIGSSe films are considered to be particularly important in this respect, owing to the fact that they are more prone to defects. In this work, CIGSSe thin films with differing S/Se ratios at their surface were synthesized by using a precursor solution and post-sulfurization heat treatment. These CIGSSe thin films were investigated with current-voltage and Kelvin probe force microscope (KPFM) analyses. Surface photovoltage (SPV), which is the difference in the work function in the dark and under illumination, was measured by using KPFM, which can examine the screening and the modification of surface charge through carrier trapping. As the concentration of S increases on the CIGSSe film surface, higher work functions and more positive SPV values were observed. Based on these measurements, we inferred the band-bending behavior of CIGSSe absorber films and proposed reasons for the improvement in solar cell performance. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Installing fiber insulation

NASA Technical Reports Server (NTRS)

Wang, D. S.; Warren, A. D. (Inventor)

1980-01-01

A method for installing fragile, high temperature insulation batting in an elongated cavity or in a resilient wire sleeve to form a resilient seal. The batting is preformed to rough dimensions and wrapped in a plastic film, the film being of a material which is fugitive at a high temperature. The film is heat sealed and trimmed to form a snugly fit skin which overlaps at least at one end to permit attachment of a pull cord. The film absorbs the tensile force of pulling the film enclosed batting through the cavity or wire mesh sleeve and is subsequently driven off by high temperature baking, leaving only the insulation in the cavity or wire mesh sleeve.

Effect of sodium dodecylbenzene sulfonate on subtilisin Carlsberg proteolysis of an immobilized ovalbumin film.

PubMed

Foose, Ladan L; Blanch, Harvey W; Radke, C J

2009-03-01

Enzymatic degradation of immobilized ovalbumin multilayer films by subtilisin Carlsberg was investigated using in situ ellipsometry. Changes in the substrate cleavage rate in the presence of an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), were assessed. Exposure of the protein film to SDBS prior to introduction of the enzyme increased the measured proteolysis rate threefold. Surfactant increased the measured film thickness, absorbing into the protein film and causing swelling. Surfactant-induced film swelling was reversible upon aqueous rinsing. Nevertheless, exposure of enzyme to the surfactant-rinsed film increased the proteolysis rate, most likely due to irreversible conformational changes induced in the substrate film by the surfactant. Simultaneous addition of SDBS with enzyme after the initial surfactant exposure did not produce additional protein-removal benefit.

Effect of plasticizer on moisture sorption isotherm of sugar palm (Arenga Pinnata) starch film

NASA Astrophysics Data System (ADS)

Jatmiko, Tri Hadi; Poeloengasih, Crescentiana D.; Prasetyo, Dwi Joko; Rosyida, Vita Taufika

2016-02-01

The effect of plasticizer type (glycerol, sorbitol) and plasticizer concentrations (30, 35, 40, 45% w/w polymer) on the moisture sorption isotherm characteristics of sugar palm (Arenga pinnata) starch films were investigated. Moisture affinity of sugar palm starch films was influenced by the plasticizer type and plasticizer concentration. The affinity of the glycerol plasticized film is stronger than that of sorbitol plasticized film. Sugar palm starch film with a higher concentration of glycerol absorbs more moisture with higher initial absorption rate than that of with sorbitol. Films with higher plasticizer concentration of glycerol and sorbitol show higher equilibrium moisture contents at the given relative humidity. The moisture sorption isotherm characteristic of sugar palm starch films can be described very well with the semi empirical 4 parameter Peleg's model.

The Optical Properties of Thin Film Reduced Graphene Oxide/Poly (3,4 Ethylenedioxtriophene):Poly (Styrene Sulfonate)(PEDOT:PSS) Fabricated by Spin Coating

NASA Astrophysics Data System (ADS)

Rokmana, Arinta W.; Asriani, A.; Suhendar, H.; Triyana, K.; Kusumaatmaja, A.; Santoso, I.

2018-04-01

Reduced Graphene Oxide (rGO) has been successfully synthesized from Graphite powder through chemical process using modified Hummers method by removing NaNO3 from reaction formula. Hydrazine hydrate 80 wt% has been chosen as reductor to eliminate the epoxy group in GO. FTIR and Uv-Vis spectroscopy result showed that Graphene Oxide (GO) and rGO were formed. Our produced rGO then used to fabricated the composite thin film rGO/PEDOT:PSS by spin coating at room temperature. The optical constant of thin film rGO/PEDOT:PSS were calculated from the absorbance spectrum of Uv-Visible spectra. The result showed that the value of coefficient absorbance of rGO dropped from 4.7×106 m-1 to 1.3×106 m-1 after doped with 0.02 mL PEDOT:PSS, then increase with the addition volume concentration of PEDOT:PSS. The value of extinction coefficient decrease from 0.31 to 0.08 after rGO doped with 0.02 ml PEDOT:PSS and then increase with the addition concentration of PEDOT:PSS. Our result show that thin film rGO/PEDOT:PSS was more transparent than that of thin film rGO.

Improved Single-Source Precursors for Solar-Cell Absorbers

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Harris, Jerry; Hepp, Aloysius

2007-01-01

Improved single-source precursor compounds have been invented for use in spray chemical vapor deposition (spray CVD) of chalcopyrite semiconductor absorber layers of thin-film cells. A "single-source precursor compound" is a single molecular compound that contains all the required elements, which when used under the spray CVD conditions, thermally decomposes to form CuIn(x)Ga(1-x)S(y)Se(2-y).

Improvement of the lipophilic-oxygen radical absorbance capacity (L-ORAC) method and single-laboratory validation.

PubMed

Watanabe, Jun; Oki, Tomoyuki; Takebayashi, Jun; Yamasaki, Koji; Takano-Ishikawa, Yuko; Hino, Akihiro; Yasui, Akemi

2013-01-01

We improved the procedure for lipophilic-oxygen radical absorbance capacity (L-ORAC) measurement for better repeatability and intermediate precision. A sealing film was placed on the assay plate, and glass vials and microdispensers equipped with glass capillaries were used. The antioxidant capacities of food extracts can be evaluated by this method with nearly the same precision as antioxidant solutions.

Whey protein film with oxygen scavenging function by incorporation of ascorbic acid.

PubMed

Janjarasskul, Theeranun; Tananuwong, Kanitha; Krochta, John M

2011-01-01

Residual O(2) in a package headspace can be removed by an O(2)-absorbing sachet, which can be harmful if swallowed by the consumer, or by a chemically-active plastic packaging film, which is difficult to recycle. An edible, O(2)-absorbing film would avoid these disadvantages. The objective of our research was to assess the O(2)-scavenging potential of an edible whey protein isolate (WPI) film incorporating ascorbic acid (AA). AA at 0.05, 0.1, or 0.2 M was added to 5% (w/w) heat-denatured WPI film-forming solutions with WPI : glycerol (Gly) ratio of 1: 1.00, 1: 0.80, or 1: 0.67. The pH of solutions was then adjusted to 3.5 (below pK(a1) of AA), to stabilize AA against oxidation, before film casting. The mechanical properties, O(2) permeabilities, and thermal transitions of films were measured. Activation of the O(2)-scavenging function of the AA-incorporated films was accomplished by adjustment of the films to pH ≥ 7. O(2)-scavenging ability of AA-incorporated WPI films was determined by measuring residual O(2) in the headspace of a high-barrier container. Incorporation of AA into WPI film decreased film tensile strength and further reduced O(2) permeability at each WPI : Gly ratio. AA-containing films adjusted to pH ≥ 7 demonstrated O(2) absorption proportional to AA content, consistent with theoretical O(2)-scavenging capacity. Thermal transition measurements indicated that AA was involved in WPI structural modification and decreased the degradation temperature of WPI-based film. The demonstrated O(2)-scavenging function, improved O(2) barrier and acceptable mechanical properties of AA-incorporated films indicate potential commercial usefulness. Ascorbic acid-incorporated whey protein film with oxygen scavenging function can be used to extend shelf lives of a wide variety of oxygen-sensitive products by eliminating headspace oxygen as well as oxygen permeating through the packaging wall over time. Edible oxygen-scavenger film has the advantages of avoiding both accidental consumption and nonrecyclability of conventional oxygen scavenger systems. © 2011 Institute of Food Technologists®

Transition-Edge Hot-Electron Microbolometers for Millimeter and Submillimeter Astrophysics

NASA Technical Reports Server (NTRS)

Hsieh, Wen-Ting; Stevenson, Thomas; U-yen, Kongpop; Wollack, Edward; Barrentine, Emily

2014-01-01

The millimeter and the submillimeter wavelengths of the electromagnetic spectrum hold a wealth of information about the evolution of the universe. In particular, cosmic microwave background (CMB) radiation and its polarization carry the oldest information in the universe, and provide the best test of the inflationary paradigm available to astronomy today. Detecting gravity waves through their imprint on the CMB polarization would have extraordinary repercussions for cosmology and physics. A transition-edge hot-electron micro - bolometer (THM) consists of a superconducting bilayer transition-edge sensor (TES) with a thin-film absorber. Unlike traditional monolithic bolometers that make use of micromachined structures, the THM em ploys the decoupling between electrons and phonons at millikelvin temperatures to provide thermal isolation. The devices are fabricated photolithographically and are easily integrated with antennas via microstrip transmission lines, and with SQUID (superconducting quantum interference device) readouts. The small volume of the absorber and TES produces a short thermal time constant that facilitates rapid sky scanning. The THM consists of a thin-film metal absorber overlapping a superconducting TES. The absorber forms the termination of a superconducting microstripline that carries RF power from an antenna. The purpose of forming a separate absorber and TES is to allow flexibility in the optimization of the two components. In particular, the absorbing film's impedance can be chosen to match the antenna, while the TES impedance can be chosen to match to the readout SQUID amplifier. This scheme combines the advantages of the TES with the advantages of planar millimeter-wave transmission line circuits. Antenna-coupling to the detectors via planar transmission lines allows the detector dimensions to be much smaller than a wavelength, so the technique can be extended across the entire microwave, millimeter, and submillimeter wavelength ranges. The circuits are fabricated using standard microlithographic techniques and are compatible with uniform, large array formats. Unlike traditional monolithic bolometers that make use of micromachined structures, the THM employs the decoupling between electrons and phonons at millikelvin temperatures to provide thermal isolation. There is no fragile membrane in the structure for thermal isolation, which improves the fabrication yield.

Structural and optical properties of copper-coated substrates for solar thermal absorbers

NASA Astrophysics Data System (ADS)

Pratesi, Stefano; De Lucia, Maurizio; Meucci, Marco; Sani, Elisa

2016-10-01

Spectral selectivity, i.e. merging a high absorbance at sunlight wavelengths to a low emittance at the wavelengths of thermal spectrum, is a key characteristics for materials to be used for solar thermal receivers. It is known that spectrally selective absorbers can raise the receiver efficiency for all solar thermal technologies. Tubular sunlight receivers for parabolic trough collector (PTC) systems can be improved by the use of spectrally selective coatings. Their absorbance is increased by deposing black films, while the thermal emittance is minimized by the use of properly-prepared substrates. In this work we describe the intermediate step in the fabrication of black-chrome coated solar absorbers, namely the fabrication and characterization of copper coatings on previously nickel-plated stainless steel substrates. We investigate the copper surface features and optical properties, correlating them to the coating thickness and to the deposition process, in the perspective to assess optimal conditions for solar absorber applications.

Modeling and optimization aspects of radiation induced grafting of 4-vinylpyridene onto partially fluorinated films

NASA Astrophysics Data System (ADS)

Nasef, Mohamed Mahmoud; Ahmad Ali, Amgad; Saidi, Hamdani; Ahmad, Arshad

2014-01-01

Modeling and optimization aspects of radiation induced grafting (RIG) of 4-vinylpyridine (4-VP) onto partially fluorinated polymers such as poly(ethylene-co-tetrafluoroethene) (ETFE) and poly(vinylidene fluoride) (PVDF) films were comparatively investigated using response surface method (RSM). The effects of independent parameters: absorbed dose, monomer concentration, grafting time and reaction temperature on the response, grafting yield (GY) were correlated through two quadratic models. The results of this work confirm that RSM is a reliable tool not only for optimization of the reaction parameters and prediction of GY in RIG processes, but also for the reduction of the number of the experiments, monomer consumption and absorbed dose leading to an improvement of the overall reaction cost.

Formation of solar cells based on Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) ferroelectric thick film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Irzaman,, E-mail: irzaman@yahoo.com; Syafutra, H., E-mail: irzaman@yahoo.com; Arif, A., E-mail: irzaman@yahoo.com

2014-02-24

Growth of Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) 1 M thick films are conducted with variation of annealing hold time of 8 hours, 15 hours, 22 hours, and 29 hours at a constant temperature of 850 °C on p-type Si (100) substrate using sol-gel method then followed by spin coating process at 3000 rpm for 30 seconds. The BST thick film electrical conductivity is obtained to be 10{sup −5} to 10{sup −4} S/cm indicate that the BST thick film is classified as semiconductor material. The semiconductor energy band gap value of BST thick film based on annealing hold time of 8more » hours, 15 hours, 22 hours, and 29 hours are 2.58 eV, 3.15 eV, 3.2 eV and 2.62 eV, respectively. The I-V photovoltaic characterization shows that the BST thick film is potentially solar cell device, and in accordance to annealing hold time of 8 hours, 15 hours, 22 hours and 29 hours have respective solar cell energy conversion efficiencies of 0.343%, 0.399%, 0.469% and 0.374%, respectively. Optical spectroscopy shows that BST thick film solar cells with annealing hold time of 8 hours, 15 hours, and 22 hours absorb effectively light energy at wavelength of ≥ 700 nm. BST film samples with annealing hold time of 29 hours absorb effectively light energy at wavelength of ≤ 700 nm. The BST thick film refraction index is between 1.1 to 1.8 at light wavelength between ±370 to 870 nm.« less

Silver Nanoparticle Enhanced Freestanding Thin-Film Silicon Solar Cells

NASA Astrophysics Data System (ADS)

Winans, Joshua David

As the supply of fossil fuels diminishes in quantity the demand for alternative energy sources will consistently increase. Solar cells are an environmentally friendly and proven technology that suffer in sales due to a large upfront cost. In order to help facilitate the transition from fossil fuels to photovoltaics, module costs must be reduced to prices well below $1/Watt. Thin-film solar cells are more affordable because of the reduced materials costs, but lower in efficiency because less light is absorbed before passing through the cell. Silver nanoparticles placed at the front surface of the solar cell absorb and reradiate the energy of the light in ways such that more of the light ends being captured by the silicon. Silver nanoparticles can do this because they have free electron clouds that can take on the energy of an incident photon through collective action. This bulk action of the electrons is called a plasmon. This work begins by discussing the economics driving the need for reduced material use, and the pros and cons of taking this step. Next, the fundamental theory of light-matter interaction is briefly described followed by an introduction to the study of plasmonics. Following that we discuss a traditional method of silver nanoparticle formation and the initial experimental studies of their effects on the ability of thin-film silicon to absorb light. Then, Finite-Difference Time-Domain simulation software is used to simulate the effects of nanoparticle morphology and size on the scattering of light at the surface of the thin-film.

Reactive sputter deposition of pyrite structure transition metal disulfide thin films: Microstructure, transport, and magnetism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baruth, A.; Manno, M.; Narasimhan, D.

2012-09-01

Transition metal disulfides crystallizing in the pyrite structure (e.g., TMS{sub 2}, with TM = Fe, Co, Ni, and Cu) are a class of materials that display a remarkably diverse array of functional properties. These properties include highly spin-polarized ferromagnetism (in Co{sub 1-x}Fe{sub x}S{sub 2}), superconductivity (in CuS{sub 2}), an antiferromagnetic Mott insulating ground state (in NiS{sub 2}), and semiconduction with close to optimal parameters for solar absorber applications (in FeS{sub 2}). Exploitation of these properties in heterostructured devices requires the development of reliable and reproducible methods for the deposition of high quality pyrite structure thin films. In this manuscript, wemore » report on the suitability of reactive sputter deposition from metallic targets in an Ar/H{sub 2}S environment as a method to achieve exactly this. Optimization of deposition temperature, Ar/H{sub 2}S pressure ratio, and total working gas pressure, assisted by plasma optical emission spectroscopy, reveals significant windows over which deposition of single-phase, polycrystalline, low roughness pyrite films can be achieved. This is illustrated for the test cases of the ferromagnetic metal CoS{sub 2} and the diamagnetic semiconductor FeS{sub 2}, for which detailed magnetic and transport characterization are provided. The results indicate significant improvements over alternative deposition techniques such as ex situ sulfidation of metal films, opening up exciting possibilities for all-sulfide heterostructured devices. In particular, in the FeS{sub 2} case it is suggested that fine-tuning of the sputtering conditions provides a potential means to manipulate doping levels and conduction mechanisms, critical issues in solar cell applications. Parenthetically, we note that conditions for synthesis of phase-pure monosulfides and thiospinels are also identified.« less

Phase Engineering of Perovskite Materials for High-Efficiency Solar Cells: Rapid Conversion of CH3NH3PbI3 to Phase-Pure CH3NH3PbCl3 via Hydrochloric Acid Vapor Annealing Post-Treatment.

PubMed

Zhou, Weiran; Zhou, Pengcheng; Lei, Xunyong; Fang, Zhimin; Zhang, Mengmeng; Liu, Qing; Chen, Tao; Zeng, Hualing; Ding, Liming; Zhu, Jun; Dai, Songyuan; Yang, Shangfeng

2018-01-17

Organometal halide CH 3 NH 3 PbI 3 (MAPbI 3 ) has been commonly used as the light absorber layer of perovskite solar cells (PSCs), and, especially, another halide element chlorine (Cl) has been often incorporated to assist the crystallization of perovskite film. However, in most cases, a predominant MAPbI 3 phase with trace of Cl - is obtained ultimately and the role of Cl involvement remains unclear. Herein, we develop a low-cost and facile method, named hydrochloric acid vapor annealing (HAVA) post-treatment, and realize a rapid conversion of MAPbI 3 to phase-pure MAPbCl 3 , demonstrating a new concept of phase engineering of perovskite materials toward efficiency enhancement of PSCs for the first time. The average grain size of perovskite film after HAVA post-treatment increases remarkably through an Ostwald ripening process, leading to a denser and smoother perovskite film with reduced trap states and enhanced crystallinity. More importantly, the generation of MAPbCl 3 secondary phase via phase engineering is beneficial for improving the carrier mobility with a more balanced carrier transport rate and enlarging the band gap of perovskite film along with optimized energy level alignment. As a result, under the optimized HAVA post-treatment time (2 min), we achieved a significant enhancement of the power conversion efficiency (PCE) of the MAPbI 3 -based planar heterojunction-PSC device from 14.02 to 17.40% (the highest PCE reaches 18.45%) with greatly suppressed hysteresis of the current-voltage response.

Does periodic lung screening of films meets standards?

PubMed

Binay, Songul; Arbak, Peri; Safak, Alp Alper; Balbay, Ege Gulec; Bilgin, Cahit; Karatas, Naciye

2016-01-01

To determine whether the workers' periodic chest x-ray screening techniques in accordance with the quality standards is the responsibility of physicians. Evaluation of differences of interpretations by physicians in different levels of education and the importance of standardization of interpretation. Previously taken chest radiographs of 400 workers who are working in a factory producing the glass run channels were evaluated according to technical and quality standards by three observers (pulmonologist, radiologist, pulmonologist assistant). There was a perfect concordance between radiologist and pulmonologist for the underpenetrated films. Whereas there was perfect concordance between pulmonologist and pulmonologist assistant for over penetrated films. Pulmonologist (52%) has interpreted the dose of the films as regular more than other observers (radiologist; 44.3%, pulmonologist assistant; 30.4%). The frequency of interpretation of the films as taken in inspiratory phase by the pulmonologist (81.7%) was less than other observers (radiologist; 92.1%, pulmonologist assistant; 92.6%). The rate of the pulmonologist (53.5%) was higher than the other observers (radiologist; 44.6%, pulmonologist assistant; 41.8%) for the assessment of the positioning of the patients as symmetrical. Pulmonologist assistant (15.3%) was the one who most commonly reported the parenchymal findings (radiologist; 2.2%, pulmonologist; 12.9%). It is necessary to reorganize the technical standards and exposure procedures for improving the quality of the chest radiographs. The reappraisal of all interpreters and continuous training of technicians is required.

Low resistivity and low compensation ratio Ga-doped ZnO films grown by plasma-assisted molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Chen, Cheng-Yu; Hsiao, Li-Han; Chyi, Jen-Inn

2015-09-01

In this study, Ga-doped ZnO (GZO) thin films were deposited on GaN templates by using plasma-assisted molecular beam epitaxy. To obtain low resistivity GZO films, in-situ post-annealing under Zn overpressure was carried out to avoid the generation of acceptor-liked Zn vacancies. The resultant films showed optical transparency over 95% in the visible spectral range. By reducing the acceptor-like defects, GZO films with compensation ratio near 0.4 and resistivity simultaneously lower than 1×10-4 Ω cm have been successfully demonstrated.

ZnO-based transparent conductive thin films via sonicated-assisted sol-gel technique

NASA Astrophysics Data System (ADS)

Malek, M. F.; Mamat, M. H.; Ismail, A. S.; Yusoff, M. M.; Mohamed, R.; Rusop, M.

2018-05-01

We report on the growth of Al-doped ZnO (AZO) thin films onto Corning 7740 glass substrates via sonicated-assisted sol-gel technique. The influence of Al dopant on crystallisation behavior, optical and electrical properties of AZO films has been systematically investigated. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction <002>. All films exhibit a transmittance above than 80-90 % along the visible range up to 800 nm and a sharp absorption onset below 400 nm corresponding to the fundamental absorption edge of ZnO.

Sulvanite (Cu 3VS 4) nanocrystals for printable thin film photovoltaics

DOE PAGES

Chen, Ching -Chin; Stone, Kevin H.; Lai, Cheng -Yu; ...

2017-09-21

Copper Vanadium Sulfide (Cu 3VS 4), also known as sulvanite, has recently emerged as a suitable absorber material for thin film photovoltaics. The synthesis of Cu 3VS 4 nanocrystals via a rapid solvothermal route is reported for the first time. The phase purity of the Cu 3VS 4 nanocrystals has been confirmed by X-ray powder diffraction (XRD) and Raman spectroscopy, while the nanoparticle size, of about 10 nm, was evaluated by transmission electron microscopy (TEM). Successful ligand exchange with sulfide, an inorganic ligand, demonstrated that the nanoparticles are amenable to surface modifications, key element in solution processing. Further annealing ofmore » as-synthesized nanocrystals under a sulfur/argon atmosphere at 600 °C, rendered highly crystalline Cu 3VS 4 powders exhibiting an impurity that could be potentially mitigated by annealing temperature optimization. Furthermore, Cu 3VS 4, formed solely from Earth-abundant elements, could provide an inexpensive, reliable approach to fabricating solution processed thin film photovoltaic absorbers.« less

Slow-muon study of quaternary solar-cell materials: Single layers and p -n junctions

NASA Astrophysics Data System (ADS)

Alberto, H. V.; Vilão, R. C.; Vieira, R. B. L.; Gil, J. M.; Weidinger, A.; Sousa, M. G.; Teixeira, J. P.; da Cunha, A. F.; Leitão, J. P.; Salomé, P. M. P.; Fernandes, P. A.; Törndahl, T.; Prokscha, T.; Suter, A.; Salman, Z.

2018-02-01

Thin films and p -n junctions for solar cells based on the absorber materials Cu (In ,G a ) Se2 and Cu2ZnSnS4 were investigated as a function of depth using implanted low energy muons. The most significant result is a clear decrease of the formation probability of the Mu+ state at the heterojunction interface as well as at the surface of the Cu (In ,G a ) Se2 film. This reduction is attributed to a reduced bonding reaction of the muon in the absorber defect layer at its surface. In addition, the activation energies for the conversion from a muon in an atomiclike configuration to a anion-bound position are determined from temperature-dependence measurements. It is concluded that the muon probe provides a measurement of the effective surface defect layer width, both at the heterojunctions and at the films. The CIGS surface defect layer is crucial for solar-cell electrical performance and additional information can be used for further optimizations of the surface.

A Filmy Black-Phosphorus Polyimide Saturable Absorber for Q-Switched Operation in an Erbium-Doped Fiber Laser.

PubMed

Feng, Tianxian; Mao, Dong; Cui, Xiaoqi; Li, Mingkun; Song, Kun; Jiang, Biqiang; Lu, Hua; Quan, Wangmin

2016-11-11

We demonstrate an erbium-doped fiber laser passively Q-switched by a black-phosphorus polyimide film. The multi-layer black-phosphorus (BP) nanosheets were prepared via a liquid exfoliation approach exploiting N -methylpyrrolidone as the dispersion liquid. By mixing the BP nanosheets with polyimide (PI), a piece of BP-PI film was obtained after evaporating the mixture in a petri dish. The BP-PI saturable absorber had a modulation depth of 0.47% and was inserted into an erbium-doped fiber laser to realize passive Q-switched operations. The repetition rate of the Q-switched laser increased from 5.73 kHz to 31.07 kHz when the laser pump was enhanced from 31.78 mW to 231.46 mW. Our results show that PI is an excellent host material to protect BP from oxidation, and the BP-PI film can act as a promising nonlinear optical device for laser applications.

Sulvanite (Cu 3VS 4) nanocrystals for printable thin film photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ching -Chin; Stone, Kevin H.; Lai, Cheng -Yu

Copper Vanadium Sulfide (Cu 3VS 4), also known as sulvanite, has recently emerged as a suitable absorber material for thin film photovoltaics. The synthesis of Cu 3VS 4 nanocrystals via a rapid solvothermal route is reported for the first time. The phase purity of the Cu 3VS 4 nanocrystals has been confirmed by X-ray powder diffraction (XRD) and Raman spectroscopy, while the nanoparticle size, of about 10 nm, was evaluated by transmission electron microscopy (TEM). Successful ligand exchange with sulfide, an inorganic ligand, demonstrated that the nanoparticles are amenable to surface modifications, key element in solution processing. Further annealing ofmore » as-synthesized nanocrystals under a sulfur/argon atmosphere at 600 °C, rendered highly crystalline Cu 3VS 4 powders exhibiting an impurity that could be potentially mitigated by annealing temperature optimization. Furthermore, Cu 3VS 4, formed solely from Earth-abundant elements, could provide an inexpensive, reliable approach to fabricating solution processed thin film photovoltaic absorbers.« less

Defect analysis and detection of micro nano structured optical thin film

NASA Astrophysics Data System (ADS)

Xu, Chang; Shi, Nuo; Zhou, Lang; Shi, Qinfeng; Yang, Yang; Li, Zhuo

2017-10-01

This paper focuses on developing an automated method for detecting defects on our wavelength conversion thin film. We analyzes the operating principle of our wavelength conversion Micro/Nano thin film which absorbing visible light and emitting infrared radiation, indicates the relationship between the pixel's pattern and the radiation of the thin film, and issues the principle of defining blind pixels and their categories due to the calculated and experimental results. An effective method is issued for the automated detection based on wavelet transform and template matching. The results reveal that this method has desired accuracy and processing speed.

Correlation between the structural and optical properties of ion-assisted hafnia thin films

NASA Astrophysics Data System (ADS)

Scaglione, Salvatore; Sarto, Francesca; Alvisi, Marco; Rizzo, Antonella; Perrone, Maria R.; Protopapa, Maria L.

2000-03-01

The ion beam assistance during the film growth is one of the most useful method to obtain dense film along with improved optical and structural properties. Afnia material is widely used in optical coating operating in the UV region of the spectrum and its optical properties depend on the production method and the physical parameters of the species involved in the deposition process. In this work afnia thin films were evaporated by an e-gun and assisted during the growth process. The deposition parameters, ion beam energy, density of ions impinging on the growing film and the number of arrival atoms from the crucible, have been related to the optical and structural properties of the film itself. The absorption coefficient and the refractive index were measured by spectrophotometric technique while the microstructure has been studied by means of x-ray diffraction. A strictly correlation between the grain size, the optical properties and the laser damage threshold measurements at 248 nm was found for the samples deposited at different deposition parameters.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woon Hyuk Chung

Polyvinyl alcohol films containing congo red are useful as gamma and electron radiation dosimeters. Absorbed doses should not exceed 500 kGy. The dose response is rather linear in a higher range, e.g., 100 to 500 kGy. The film is relatively stable before and after irradiation for quite a long time against fading, for example, a change of [approximately]10% in 1 yr following irradiation at room temperature.

EXPERIMENTAL EVALUATION OF DOSIMETRIC CHARACTERIZATION OF GAFCHROMIC EBT3 AND EBT-XD FILMS FOR CLINICAL CARBON ION BEAMS.

PubMed

Yonai, Shunsuke; Arai, Chinatsu; Shimoyama, Kaoru; Fournier-Bidoz, Nathalie

2018-02-03

Radiochromic film is a very useful tool for 2D dosimetric measurements in radiotherapy because it is self-developing and has very high-spatial resolution. However, considerable care has to be taken in ion beam radiotherapy owing to the quenching effect of high-linear energy transfer (LET) radiation. In this study, the dose responses of GAFchromic EBT3 and EBT-XD films were experimentally investigated using the clinical carbon ion beam at the Heavy Ion Medical Accelerator in Chiba. Results showed that the relations between absorbed dose and net optical density could be expressed well using an equation proposed by Reinhardt (2015). The quenching effect was evaluated by determining their relative efficiencies for photon irradiation as a function of LET. A correction equation derived in this study allowed the absorbed dose to be determined in the small irradiation field used for carbon ion radiotherapy eye treatments. This study contributes to establishing an absolute dosimetry procedure for heavy ion beams using radiochromic film. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Titanium Dioxide (TiO2) film as a new saturable absorber for generating mode-locked Thulium-Holmium doped all-fiber laser

NASA Astrophysics Data System (ADS)

Mohd Rusdi, Muhammad Farid; Latiff, Anas Abdul; Paul, Mukul Chandra; Das, Shyamal; Dhar, Anirban; Ahmad, Harith; Harun, Sulaiman Wadi

2017-03-01

We report the generation of mode-locked thulium-holmium doped fiber laser (THDFL) at 1979 nm. This is a first demonstration of mode-locked by using Titanium Dioxide (TiO2) film as a saturable absorber (SA). A piece of 1 mm×1 mm TiO2 film was sandwiched in between two fiber ferrule in the cavity. Fabrication process of TiO2 film incorporated a TiO2 and a polyvinyl alcohol (PVA). The stable 9 MHz repetition rate of mode-locked mode operation with 58 dB SNR was generated under pump power of 902-1062 mW. At maximum pump power, the mode-locked THDFL has output power and pulse energy of 15 mW and 1.66 nJ, respectively. Our results demonstrate the TiO2 can be used promisingly in ultrafast photonics applications.

Deposition of ultra thin CuInS₂ absorber layers by ALD for thin film solar cells at low temperature (down to 150 °C).

PubMed

Schneider, Nathanaelle; Bouttemy, Muriel; Genevée, Pascal; Lincot, Daniel; Donsanti, Frédérique

2015-02-06

Two new processes for the atomic layer deposition of copper indium sulfide (CuInS₂) based on the use of two different sets of precursors are reported. Metal chloride precursors (CuCl, InCl₃) in combination with H2S imply relatively high deposition temperature (Tdep = 380 °C), and due to exchange reactions, CuInS₂ stoechiometry was only achieved by depositing In₂S3 layers on a CuxS film. However, the use of acac- metal precursors (Cu(acac)₂, In(acac)₃) allows the direct deposition of CuInS₂ at temperature as low as 150 °C, involving in situ copper-reduction, exchange reaction and diffusion processes. The morphology, crystallographic structure, chemical composition and optical band gap of thin films were investigated using scanning electronic microscope, x-ray diffraction under grazing incidence conditions, x-ray fluorescence, energy dispersive spectrometry, secondary ion mass spectrometry, x-ray photoelectron spectroscopy and UV-vis spectroscopy. Films were implemented as ultra-thin absorbers in a typical CIS-solar cell architecture and allowed conversion efficiencies up to 2.8%.

Antireflection coating on metallic substrates for solar energy and display applications

NASA Astrophysics Data System (ADS)

Hsiao, Wei-Yuan; Tang, Chien-Jen; Lee, Kun-Hsien; Jaing, Cheng-Chung; Kuo, Chien-Cheng; Chen, Hsi-Chao; Chang, Hsing-Hua; Lee, Cheng-Chung

2010-08-01

Normally metallic films are required for solar energy and display related coatings. To increase the absorbing efficiency or contrast, it is necessary to apply an antireflection coating (ARC) on the metal substrate. However, the design of a metal substrate is very different from the design of a dielectric substrate, since the optical constant of metallic thin film is very dependent on its thickness and microstructure. In this study, we design and fabricate ARCs on Al substrates using SiO2 and Nb2O5 as the dielectric materials and Nb for the metal films. The ARC successfully deposited on the Al substrate had the following structure: air/SiO2/Nb2O5/Metal/Nb2O5/Al. The measured average reflectance of the ARC is less than 1% in the visible region. We found that it is better to use a highly refractive material than a low refractive material. The thickness of the metallic film can be thicker with the result that it is easier to control and has a lesser total thickness. The total thickness of the ARC is less than 200 nm. We successfully fabricated a solar absorber and OLED device with the ARC structure were successfully fabricated.

Multi-target determination of organic ultraviolet absorbents in organism tissues by ultrasonic assisted extraction and ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Peng, Xianzhi; Jin, Jiabin; Wang, Chunwei; Ou, Weihui; Tang, Caiming

2015-03-06

A sensitive and reliable method was developed for multi-target determination of 13 most widely used organic ultraviolet (UV) absorbents (including UV filters and UV stabilizers) in aquatic organism tissues. The organic UV absorbents were extracted using ultrasonic-assisted extraction, purified via gel permeation chromatography coupled with silica gel column chromatography, and determined by ultra-high performance liquid chromatography-tandem mass spectrometry. Recoveries of the UV absorbents from organism tissues mostly ranged from 70% to 120% from fish filet with satisfactory reproducibility. Method quantification limits were 0.003-1.0ngg(-1) dry weight (dw) except for 2-ethylhexyl 4-methoxycinnamate. This method has been applied to analysis of the UV absorbents in wild and farmed aquatic organisms collected from the Pearl River Estuary, South China. 2-Hydroxy-4-methoxybenzophenone and UV-P were frequently detected in both wild and farmed marine organisms at low ngg(-1)dw. 3-(4-Methylbenzylidene)camphor and most of the benzotriazole UV stabilizers were also frequently detected in maricultured fish. Octocrylene and 2-ethylhexyl 4-methoxycinnamate were not detected in any sample. This work lays basis for in-depth study about bioaccumulation and biomagnification of the UV absorbents in marine environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Anomalous electronic heat capacity of copper nanowires at sub-Kelvin temperatures

NASA Astrophysics Data System (ADS)

Viisanen, K. L.; Pekola, J. P.

2018-03-01

We have measured the electronic heat capacity of thin film nanowires of copper and silver at temperatures 0.1-0.3 K; the films were deposited by standard electron-beam evaporation. The specific heat of the Ag films of sub-100-nm thickness agrees with the bulk value and the free-electron estimate, whereas that of similar Cu films exceeds the corresponding reference values by one order of magnitude. The origin of the anomalously high heat capacity of copper films remains unknown for the moment. Based on the small heat capacity at low temperatures and the possibility to devise a tunnel probe thermometer on it, metal films form a promising absorber material, e.g., for microwave photon calorimetry.

Determination of acoustic properties of thin polymer films utilizing the frequency dependence of the reflection coefficient of ultrasound.

PubMed

Tohmyoh, Hironori; Sakamoto, Yuhei

2015-11-01

This paper reports on a technique to measure the acoustic properties of a thin polymer film utilizing the frequency dependence of the reflection coefficient of ultrasound reflected back from a system comprising a reflection plate, the film, and a material that covers the film. The frequency components of the echo reflected from the back of the plate, where the film is attached, take their minimum values at the resonant frequency, and from these frequency characteristics, the acoustic impedance, sound velocity, and the density of the film can be determined. We applied this technique to characterize an ion exchange membrane, which has high water absorbability, and successfully determined the acoustic properties of the membrane without getting it wet.

Analyzing optical properties of thin vanadium oxide films through semiconductor-to-metal phase transition using spectroscopic ellipsometry

NASA Astrophysics Data System (ADS)

Sun, Jianing; Pribil, Greg K.

2017-11-01

We investigated the optical behaviors of vanadium dioxide (VO2) films through the semiconductor-to-metal (STM) phase transition using spectroscopic ellipsometry. Correlations between film thickness and refractive index were observed resulting from the absorbing nature of these films. Simultaneously analyzing data at multiple temperatures using Kramers-Kronig consistent oscillator models help identify film thickness. Nontrivial variations in resulting optical constants were observed through STM transition. As temperature increases, a clear increase is observed in near infrared absorption due to Drude losses that accompany the transition from semiconducting to metallic phases. Thin films grown on silicon and sapphire substrate present different optical properties and thermal hysteresis due to lattice stress and compositional differences.

Automated Geometry assisted PEC for electron beam direct write nanolithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ocola, Leonidas E.; Gosztola, David J.; Rosenmann, Daniel

Nanoscale geometry assisted proximity effect correction (NanoPEC) is demonstrated to improve PEC for nanoscale structures over standard PEC, in terms of feature sharpness for sub-100 nm structures. The method was implemented onto an existing commercially available PEC software. Plasmonic arrays of crosses were fabricated using regular PEC and NanoPEC, and optical absorbance was measured. Results confirm that the improved sharpness of the structures leads to increased sharpness in the optical absorbance spectrum features. We also demonstrated that this method of PEC is applicable to arbitrary shaped structures beyond crosses.

Plasma-assisted microwave processing of materials

NASA Technical Reports Server (NTRS)

Barmatz, Martin (Inventor); Jackson, Henry (Inventor); Ylin, Tzu-yuan (Inventor)

1998-01-01

A microwave plasma assisted method and system for heating and joining materials. The invention uses a microwave induced plasma to controllably preheat workpiece materials that are poorly microwave absorbing. The plasma preheats the workpiece to a temperature that improves the materials' ability to absorb microwave energy. The plasma is extinguished and microwave energy is able to volumetrically heat the workpiece. Localized heating of good microwave absorbing materials is done by shielding certain parts of the workpiece and igniting the plasma in the areas not shielded. Microwave induced plasma is also used to induce self-propagating high temperature synthesis (SHS) process for the joining of materials. Preferably, a microwave induced plasma preheats the material and then microwave energy ignites the center of the material, thereby causing a high temperature spherical wave front from the center outward.

Modeling and prediction of extraction profile for microwave-assisted extraction based on absorbed microwave energy.

PubMed

Chan, Chung-Hung; Yusoff, Rozita; Ngoh, Gek-Cheng

2013-09-01

A modeling technique based on absorbed microwave energy was proposed to model microwave-assisted extraction (MAE) of antioxidant compounds from cocoa (Theobroma cacao L.) leaves. By adapting suitable extraction model at the basis of microwave energy absorbed during extraction, the model can be developed to predict extraction profile of MAE at various microwave irradiation power (100-600 W) and solvent loading (100-300 ml). Verification with experimental data confirmed that the prediction was accurate in capturing the extraction profile of MAE (R-square value greater than 0.87). Besides, the predicted yields from the model showed good agreement with the experimental results with less than 10% deviation observed. Furthermore, suitable extraction times to ensure high extraction yield at various MAE conditions can be estimated based on absorbed microwave energy. The estimation is feasible as more than 85% of active compounds can be extracted when compared with the conventional extraction technique. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fast microwave assisted pyrolysis of biomass using microwave absorbent.

PubMed

Borges, Fernanda Cabral; Du, Zhenyi; Xie, Qinglong; Trierweiler, Jorge Otávio; Cheng, Yanling; Wan, Yiqin; Liu, Yuhuan; Zhu, Rongbi; Lin, Xiangyang; Chen, Paul; Ruan, Roger

2014-03-01

A novel concept of fast microwave assisted pyrolysis (fMAP) in the presence of microwave absorbents was presented and examined. Wood sawdust and corn stover were pyrolyzed by means of microwave heating and silicon carbide (SiC) as microwave absorbent. The bio-oil was characterized, and the effects of temperature, feedstock loading, particle sizes, and vacuum degree were analyzed. For wood sawdust, a temperature of 480°C, 50 grit SiC, with 2g/min of biomass feeding, were the optimal conditions, with a maximum bio-oil yield of 65 wt.%. For corn stover, temperatures ranging from 490°C to 560°C, biomass particle sizes from 0.9mm to 1.9mm, and vacuum degree lower than 100mmHg obtained a maximum bio-oil yield of 64 wt.%. This study shows that the use of microwave absorbents for fMAP is feasible and a promising technology to improve the practical values and commercial application outlook of microwave based pyrolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microwave absorption property of the diatomite coated by Fe-CoNiP films

NASA Astrophysics Data System (ADS)

Yan, Zhenqiang; Cai, Jun; Xu, Yonggang; Zhang, Deyuan

2015-08-01

A bio-absorbent of Fe-CoNiP coated on the diatomite was fabricated by way of electroless plating of CoNiP and subsequent chemical vapor deposition of Fe. The surface morphology and composition of the above-mentioned diatomite particles at different stage were characterized with the scanning electron microscopy and the energy spectrum analysis respectively, and the results showed that the diatomite was successfully coated with CoNoP and Fe (carbony iron). The complex permittivity and permeability of composites filled with the bio-absorbent and paraffin was measured in frequency range of 2-18 GHz, and then the microwave reflection loss (RL) and the shielding effectiveness (SE) were calculated. The results showed that the permittivity and the permeability were both enlarged as Fe films were coated onto the CoNiP-coated diatomite, which was attributed to the excellent electromagnetic property of carbonyl irons. The composites made with the Fe-CoNiP diatomite had a better absorbing property (minimum RL -11.0 dB) as well as the shielding property (maximum SE 5.6 dB) at thickness 2 mm. It indicated the absorption property was mainly due to the attenuation on the microwave, and the Fe-CoNiP diatomite could be an effective absorbent with low-density.

Radiochromic film calibration for the RQT9 quality beam

NASA Astrophysics Data System (ADS)

Costa, K. C.; Gomez, A. M. L.; Alonso, T. C.; Mourao, A. P.

2017-11-01

When ionizing radiation interacts with matter it generates energy deposition. Radiation dosimetry is important for medical applications of ionizing radiation due to the increasing demand for diagnostic radiology and radiotherapy. Different dosimetry methods are used and each one has its advantages and disadvantages. The film is a dose measurement method that records the energy deposition by the darkening of its emulsion. Radiochromic films have a little visible light sensitivity and respond better to ionizing radiation exposure. The aim of this study is to obtain the resulting calibration curve by the irradiation of radiochromic film strips, making it possible to relate the darkening of the film with the absorbed dose, in order to measure doses in experiments with X-ray beam of 120 kV, in computed tomography (CT). Film strips of GAFCHROMIC XR-QA2 were exposed according to RQT9 reference radiation, which defines an X-ray beam generated from a voltage of 120 kV. Strips were irradiated in "Laboratório de Calibração de Dosímetros do Centro de Desenvolvimento da Tecnologia Nuclear" (LCD / CDTN) at a dose range of 5-30 mGy, corresponding to the range values commonly used in CT scans. Digital images of the irradiated films were analyzed by using the ImageJ software. The darkening responses on film strips according to the doses were observed and they allowed obtaining the corresponding numeric values to the darkening for each specific dose value. From the numerical values of darkening, a calibration curve was obtained, which correlates the darkening of the film strip with dose values in mGy. The calibration curve equation is a simplified method for obtaining absorbed dose values using digital images of radiochromic films irradiated. With the calibration curve, radiochromic films may be applied on dosimetry in experiments on CT scans using X-ray beam of 120 kV, in order to improve CT acquisition image processes.

Effect of Indium nano-sandwiching on the structural and optical performance of ZnSe films

NASA Astrophysics Data System (ADS)

Al Garni, S. E.; Qasrawi, A. F.

In the current study, we attempted to explore the effects of the Indium nanosandwiching on the mechanical and optical properties of the physically evaporated ZnSe thin films by means of X-ray diffractions and ultraviolet spectrophotometry techniques. While the thickness of each layer of ZnSe was fixed at 1.0 μm, the thickness of the nanosandwiched Indium thin films was varied in the range of 25-100 nm. It was observed that the as grown ZnSe films exhibits cubic and hexagonal nature of crystallization as those of the ZnSe powders before the film deposition. The cubic phases weighs ∼70% of the structure. The analysis of this phases revealed that there is a systematic variation process presented by the decreasing of; the lattice constant, compressing strain, stress, stacking faults and dislocation intensity and increasing grain size resulted from increasing the Indium layer thickness in the range of 50-100 nm. In addition, the nanosandwiching of Indium between two layers of ZnSe is observed to enhance the absorbability of the ZnSe. Particularly, at incident photon energy of 2.38 eV the absorbability of the ZnSe films which are sandwiched with 100 nm Indium is increased by 13.8 times. Moreover, increasing the thickness of the Indium layer shrinks the optical energy band gap. These systematic variations in mechanical and optical properties are assigned to the better recrystallization process that is associated with Indium insertion which in turn allows total internal energy redistribution in the ZnSe films through the enlargement of grains.

Study of the Physics of Insulating Films as Related to the Reliability of Metal-Oxide Semiconductor Devices

DTIC Science & Technology

1980-11-01

materials work and sample preparation of D.W. Dong; the technical assistance of F.L. Pesavento and J.A. Calise; the assistance in device fabrication...FILMS D.J. DiMaria R. Ghez D.W. Dong I.B.M. Thomas J. Watson Research Center Yorktown Heights, New York 10598 Technical Assistance of F.L. Pesavento and... Pesavento and J.A. Calise; the assistance with gate metallizations by the Silicon Facility and Central Scientific Services at the T.J. Watson

Studies on the performance of TiO{sub 2} thin films as protective layer to chlorophyll in Ocimum tenuiflorum L from UV radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malliga, P.; Selvi, B. Karunai; Pandiarajan, J.

Thin films of TiO{sub 2} were prepared on glass substrates using sol-gel dip coating technique. The films with 10 coatings were prepared and annealed at temperatures 350°C, 450°C and 550°C for 1 hour in muffle furnace. The annealed films were characterized by X – Ray diffraction (XRD), UV – Visible, AFM, Field Effect Scanning Electron Microscopy (FESEM) and EDAX studies. Chlorophyll has many health benefits due to its structural similarity to human blood and its good chelating ability. It has antimutagenic and anticarcinogenic properties. UV light impairs photosynthesis and reduces size, productivity, and quality in many of the crop plantmore » species. Increased exposure of UV light reduces chlorophyll contents a, b and total content in plants. Titanium Dioxide (TiO{sub 2}) is a wide band gap semiconductor and efficient light harvester. TiO{sub 2} has strong UltraViolet (UV) light absorbing capability. Here, we have studied the performance of TiO{sub 2} thin films as a protective layer to the chlorophyll contents present in medicinal plant, tulsi (Ocimum tenuiflorum L) from UV radiation. The study reveals that crystallite size increases, transmittance decreases and chlorophyll contents increases with increase in annealing temperature. This study showed that TiO{sub 2} thin films are good absorber of UV light and protect the chlorophyll contents a, b and total content in medicinal plants.« less

Polycrystalline BiFeO{sub 3} thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogle, K. A., E-mail: kashinath.bogle@gmail.com; Narwade, R. D.; Mahabole, M. P.

2016-05-06

We are reporting photosensitivity property of BiFeO{sub 3} thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO{sub 3}/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

Optical properties of YbF3-CaF2 composite thin films deposited by electron-beam evaporation

NASA Astrophysics Data System (ADS)

Wang, Songlin; Mi, Gaoyuan; Zhang, Jianfu; Yang, Chongmin

2018-03-01

We studied electron-beam evaporated YbF3-CaF2 composite films on ZnS substrate at different deposition parameters. The optical properties of films have been fitted, the surface roughness have been measured by AFM. The results of experiments indicated that increased the refractive indices, extinction coefficients, and surface roughness at higher deposition rate. The refractive index of composite film deposited by electron-beam evaporation with assisted-ion source was obviously higher than it without assisted-ion source.

Simultaneous phase and morphology controllable synthesis of copper selenide films by microwave-assisted nonaqueous approach

NASA Astrophysics Data System (ADS)

Li, Jing; Fa, Wenjun; Li, Yasi; Zhao, Hongxiao; Gao, Yuanhao; Zheng, Zhi

2013-02-01

Copper selenide films with different phase and morphology were synthesized on copper substrate through controlling reaction solvent by microwave-assisted nonaqueous approach. The films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The result showed that the pure films could be obtained using cyclohexyl alcohol or benzyl alcohol as solvent. The cubic Cu2-xSe dendrites were synthesized in cyclohexyl alcohol reaction system and hexagonal CuSe flaky crystals were obtained with benzyl alcohol as solvent.

Calibration of GafChromic EBT3 for absorbed dose measurements in 5 MeV proton beam and (60)Co γ-rays.

PubMed

Vadrucci, M; Esposito, G; Ronsivalle, C; Cherubini, R; Marracino, F; Montereali, R M; Picardi, L; Piccinini, M; Pimpinella, M; Vincenti, M A; De Angelis, C

2015-08-01

To study EBT3 GafChromic film in low-energy protons, and for comparison purposes, in a reference (60)Co beam in order to use it as a calibrated dosimetry system in the proton irradiation facility under construction within the framework of the Oncological Therapy with Protons (TOP)-Intensity Modulated Proton Linear Accelerator for RadioTherapy (IMPLART) Project at ENEA-Frascati, Italy. EBT3 film samples were irradiated at the Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Legnaro, Italy, with a 5 MeV proton beam generated by a 7 MV Van de Graaff CN accelerator. The nominal dose rates used were 2.1 Gy/min and 40 Gy/min. The delivered dose was determined by measuring the particle fluence and the energy spectrum in air with silicon surface barrier detector monitors. A preliminary study of the EBT3 film beam quality dependence in low-energy protons was conducted by passively degrading the beam energy. EBT3 films were also irradiated at ENEA-National Institute of Ionizing Radiation Metrology with gamma radiation produced by a (60)Co source characterized by an absorbed dose to water rate of 0.26 Gy/min as measured by a calibrated Farmer type ionization chamber. EBT3 film calibration curves were determined by means of a set of 40 film pieces irradiated to various doses ranging from 0.5 Gy to 30 Gy absorbed dose to water. An EPSON Expression 11000XL color scanner in transmission mode was used for film analysis. Scanner response stability, intrafilm uniformity, and interfilm reproducibility were verified. Optical absorption spectra measurements were performed on unirradiated and irradiated EBT3 films to choose the most sensitive color channel to the dose range used. EBT3 GafChromic films show an under response up to about 33% for low-energy protons with respect to (60)Co gamma radiation, which is consistent with the linear energy transfer dependence already observed with higher energy protons, and a negligible dose-rate dependence in the 2-40 Gy/min range. Short- and long-term scanner stabilities were 0.5% and 1.5%, respectively; film uniformity and reproducibility were better than 0.5%. The main purpose of this study was to implement EBT3 dosimetry in the proton low-energy radiobiology line of the TOP-IMPLART accelerator, having a maximum energy of 7 MeV. Low-energy proton and (60)Co calibrated sources were used to investigate the behavior of film response vs to be written in italicum dose. The calibration in 5 MeV protons is currently used for dose assessment in the radiobiological experiments at the TOP-IMPLART accelerator carried out at that energy value.

Does periodic lung screening of films meets standards?

PubMed Central

Binay, Songul; Arbak, Peri; Safak, Alp Alper; Balbay, Ege Gulec; Bilgin, Cahit; Karatas, Naciye

2016-01-01

Objective: To determine whether the workers’ periodic chest x-ray screening techniques in accordance with the quality standards is the responsibility of physicians. Evaluation of differences of interpretations by physicians in different levels of education and the importance of standardization of interpretation. Methods: Previously taken chest radiographs of 400 workers who are working in a factory producing the glass run channels were evaluated according to technical and quality standards by three observers (pulmonologist, radiologist, pulmonologist assistant). There was a perfect concordance between radiologist and pulmonologist for the underpenetrated films. Whereas there was perfect concordance between pulmonologist and pulmonologist assistant for over penetrated films. Results: Pulmonologist (52%) has interpreted the dose of the films as regular more than other observers (radiologist; 44.3%, pulmonologist assistant; 30.4%). The frequency of interpretation of the films as taken in inspiratory phase by the pulmonologist (81.7%) was less than other observers (radiologist; 92.1%, pulmonologist assistant; 92.6%). The rate of the pulmonologist (53.5%) was higher than the other observers (radiologist; 44.6%, pulmonologist assistant; 41.8%) for the assessment of the positioning of the patients as symmetrical. Pulmonologist assistant (15.3%) was the one who most commonly reported the parenchymal findings (radiologist; 2.2%, pulmonologist; 12.9%). Conclusion: It is necessary to reorganize the technical standards and exposure procedures for improving the quality of the chest radiographs. The reappraisal of all interpreters and continuous training of technicians is required. PMID:28083054

Copper cladding on polymer surfaces by ionization-assisted deposition

NASA Astrophysics Data System (ADS)

Kohno, Tomoki; Tanaka, Kuniaki; Usui, Hiroaki

2018-03-01

Copper thin films were prepared on poly(ethylene terephthalate) (PET) and polyimide (PI) substrates by an ionization-assisted vapor deposition method. The films had a polycrystalline structure, and their crystallite size decreased with increasing ion acceleration voltage V a. Ion acceleration was effective in reducing the surface roughness of the films. Cross-sectional transmission electron microscopy revealed that the copper/polymer interface showed increased corrugation with increasing V a. The increase in V a also induced the chemical modification of polymer chains of the PET substrate, but the PI substrate underwent smaller modification after ion bombardment. Most importantly, the adhesion strength between the copper film and the PET substrate increased with increasing V a. It was concluded that ionization-assisted deposition is a promising technique for preparing metal clad layers on flexible polymer substrates.

Homojunction GaAs solar cells grown by close space vapor transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boucher, Jason W.; Ritenour, Andrew J.; Greenaway, Ann L.

2014-06-08

We report on the first pn junction solar cells grown by homoepitaxy of GaAs using close space vapor transport (CSVT). Cells were grown both on commercial wafer substrates and on a CSVT absorber film, and had efficiencies reaching 8.1%, open circuit voltages reaching 909 mV, and internal quantum efficiency of 90%. The performance of these cells is partly limited by the electron diffusion lengths in the wafer substrates, as evidenced by the improved peak internal quantum efficiency in devices fabricated on a CSVT absorber film. Unoptimized highly-doped n-type emitters also limit the photocurrent, indicating that thinner emitters with reduced doping,more » and ultimately wider band gap window or surface passivation layers, are required to increase the efficiency.« less

Application of ICP-OES to the determination of CuIn(1-x)Ga(x)Se2 thin films used as absorber materials in solar cell devices.

PubMed

Fernández-Martínez, Rodolfo; Caballero, Raquel; Guillén, Cecilia; Gutiérrez, María Teresa; Rucandio, María Isabel

2005-05-01

CuIn(1-x)Ga(x)Se2 [CIGS; x=Ga/(In+Ga)] thin films are among of the best candidates as absorber materials for solar cell applications. The material quality and main properties of the polycrystalline absorber layer are critically influenced by deviations in the stoichiometry, particularly in the Cu/(In+Ga) atomic ratio. In this work a simple, sensitive and accurate method has been developed for the quantitative determination of these thin films by inductively coupled plasma optical emission spectrometry (ICP-OES). The proposed method involves an acid digestion of the samples to achieve the complete solubilization of CIGS, followed by the analytical determination by ICP-OES. A digestion procedure with 50% HNO3 alone or in the presence of 10% HCl was performed to dissolve those thin films deposited on glass or Mo-coated glass substrates, respectively. Two analytical lines were selected for each element (Cu 324.754 and 327.396 nm, Ga 294.364 and 417.206 nm, In 303.936 and 325.609 nm, Se 196.090 and 203.985 nm, and Mo 202.030 and 379.825 nm) and a study of spectral interferences was performed which showed them to be suitable, since they offered a high sensitivity and no significant inter-element interferences were detected. Detection limits for all elements at the selected lines were found to be appropriate for this kind of application, and the relative standard deviations were lower than 1.5% for all elements with the exception of Se (about 5%). The Cu/(In+Ga) atomic ratios obtained from the application of this method to CIGS thin films were consistent with the study of the structural and morphological properties by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Investigation of ZrO x /ZrC-ZrN/Zr thin-film structural evolution and their degradation using X-ray diffraction and Raman spectrometry

NASA Astrophysics Data System (ADS)

Usmani, B.; Vijay, V.; Chhibber, R.; Dixit, A.

2016-11-01

The thin-film structures of DC/FR magnetron-sputtered ZrO x /ZrC-ZrN/Zr tandem solar-selective coatings are investigated using X-ray diffraction and room-temperature Raman spectroscopic measurements. These studies suggest that the major contribution is coming from h-ZrN0.28, c-ZrC, h-Zr3C2 crystallographic phases in ZrN-ZrC absorber layer, in conjunction with mixed ZrO x crystallographic phases. The change in structure for thermally annealed samples has been examined and observed that cubic and hexagonal ZrO x phase converted partially into tetragonal and monoclinic ZrO x phases, whereas hexagonal and cubic ZrN phases, from absorber layer, have not been observed for these thermally treated samples in air. These studies suggest that thermal treatment may lead to the loss of ZrN phase in absorber, degrading the thermal response for the desired wavelength range in open ambient conditions in contrast to vacuum conditions.

Graphene oxide-based efficient and scalable solar desalination under one sun with a confined 2D water path.

PubMed

Li, Xiuqiang; Xu, Weichao; Tang, Mingyao; Zhou, Lin; Zhu, Bin; Zhu, Shining; Zhu, Jia

2016-12-06

Because it is able to produce desalinated water directly using solar energy with minimum carbon footprint, solar steam generation and desalination is considered one of the most important technologies to address the increasingly pressing global water scarcity. Despite tremendous progress in the past few years, efficient solar steam generation and desalination can only be achieved for rather limited water quantity with the assistance of concentrators and thermal insulation, not feasible for large-scale applications. The fundamental paradox is that the conventional design of direct absorber-bulk water contact ensures efficient energy transfer and water supply but also has intrinsic thermal loss through bulk water. Here, enabled by a confined 2D water path, we report an efficient (80% under one-sun illumination) and effective (four orders salinity decrement) solar desalination device. More strikingly, because of minimized heat loss, high efficiency of solar desalination is independent of the water quantity and can be maintained without thermal insulation of the container. A foldable graphene oxide film, fabricated by a scalable process, serves as efficient solar absorbers (>94%), vapor channels, and thermal insulators. With unique structure designs fabricated by scalable processes and high and stable efficiency achieved under normal solar illumination independent of water quantity without any supporting systems, our device represents a concrete step for solar desalination to emerge as a complementary portable and personalized clean water solution.

Second-harmonic generation from Z-type Langmuir-Blodgett films of a transparent dye and a comparison of the properties when the layers are interleaved with poly(t-butyl methacrylate)

NASA Astrophysics Data System (ADS)

Ashwell, Geoffrey J.; Ranjan, Rakesh

1998-10-01

The Langmuir-Blodgett (LB) film structure of E-4-[(N- octadecyl-6,7,8-trihydro-5-isoquinolylidene)methyl]-N,N- dibutylaniline octadecylsulfate is non-centrosymmetric when the dye is deposited on the up-stroke (Z-type) and when the layers are interleaved with poly(t-butyl methacrylate). The second-harmonic intensity increases as I(N)2(omega ) equals I(1)2(omega )N2, where N is the number of active layers, and the intensity is further enhanced when the dye is mixed in a 1 to 1 ratio with octadecanoic acid. The second-order susceptibility and repeat lattice spacing of the mixed LB films are as follows: (chi) zzz(2) equals 76 pm V-1 at 1.064 micrometers and l equals 3.15 nm layer-1 when Z-type; (chi) zzz(2) equals 52 pm V-1 and l equals 4.13 nm bilayer-1 when interleaved. The films are transparent at the fundamental wavelength and have a slight absorbance of ca. 5 X 10-4 per dye layer at 532 nm. The second-harmonic intensity is the strongest to date from such a weakly absorbing LB film and this is attributed to the close proximity of the charge-transfer band and to an optimized packing arrangement.

High efficient light absorption and nanostructure-dependent birefringence of a metal-dielectric symmetrical layered structure

NASA Astrophysics Data System (ADS)

Jen, Yi-Jun; Jhang, Yi-Ciang; Liu, Wei-Chih

2017-08-01

A multilayer that comprises ultra-thin metal and dielectric films has been investigated and applied as a layered metamaterial. By arranging metal and dielectric films alternatively and symmetrically, the equivalent admittance and refractive index can be tailored separately. The tailored admittance and refractive index enable us to design optical filters with more flexibility. The admittance matching is achieved via the admittance tracing in the normalized admittance diagram. In this work, an ultra-thin light absorber is designed as a multilayer composed of one or several cells. Each cell is a seven-layered film stack here. The design concept is to have the extinction as large as possible under the condition of admittance matching. For a seven-layered symmetrical film stack arranged as Ta2O5 (45 nm)/ a-Si (17 nm)/ Cr (30 nm)/ Al (30 nm)/ Cr (30 nm)/ a-Si (17 nm)/ Ta2O5 (45 nm), its mean equivalent admittance and extinction coefficient over the visible regime is 1.4+0.2i and 2.15, respectively. The unit cell on a transparent BK7 glass substrate absorbs 99% of normally incident light energy for the incident medium is glass. On the other hand, a transmission-induced metal-dielectric film stack is investigated by using the admittance matching method. The equivalent anisotropic property of the metal-dielectric multilayer varied with wavelength and nanostructure are investigated here.

Influence of dipping cycles on physical, optical, and electrical properties of Cu 2 NiSnS 4 : Direct solution dip coating for photovoltaic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mokurala, Krishnaiah; Mallick, Sudhanshu; Bhargava, Parag

Direct solution coating technique has emerged as a promising economically viable process for earth abundant chalcogenide absorber materials for photovoltaic applications. Here, direct ethanol based dip coating of earth abundant Cu2NiSnS4 (CNTS) films on soda lime glass (SLG), molybdenum coated glass (Mo), and fluorine doped tin oxide coated glass (FTO) substrates is investigated. The structural and morphological properties of pre-annealed and sulfurized CNTS films coated on SLG, FTO, and Mo substrates are reported. The influence of dipping cycles on composition and optoelectronic properties of pre-annealed and sulfurized CNTS films deposited on SLG substrate is presented. Energy dispersive spectroscopy (EDS) andmore » X-ray fluorescence (XRF) analysis reveal how changes in thickness and elemental composition affect morphology and optoelectronic properties. The obtained absorption coefficient, optical bandgap, resistivity and mobility of pre - annealed and sulfurized films are found to be 104 cm-1, 1.5 eV, 0.48 Ocm, 3.4 cm2/Vs and 104 cm-1, 1.29 eV, 0.14 Ocm, 11.0 cm2/Vs, respectively. These properties are well suited for photovoltaic applications and lead to the conclusion that the direct ethanol based dip coating can be an alternative economically viable process for the fabrication of earth abundant CNTS absorber layers for thin film solar cells.« less

Illuminating the Potential of Thin-Film Photovoltaics

NASA Astrophysics Data System (ADS)

Katahara, John K.

Widespread adoption of photovoltaics (PV) as an alternative electricity source will be predicated upon improvements in price performance compared to traditional power sources. Solution processing of thin-film PV is one promising way to reduce the capital expenditure (CAPEX) of manufacturing solar cells. However, it is imperative that a shift to solution processing does not come at the expense of device performance. One particularly problematic parameter for thin-film PV has historically been the open-circuit voltage (VOC ). As such, there is a pressing need for characterization tools that allow us to quickly and accurately evaluate the potential performance of solution-processed PV absorber layers. This work describes recent progress in developing photoluminescence (PL) techniques for probing optoelectronic quality in semiconductors. We present a generalized model of absorption that encompasses ideal direct-gap semiconductor absorption and various band tail models. This powerful absorption model is used to fit absolute intensity PL data and extract quasi-Fermi level splitting (maximum attainable VOC) for a variety of PV absorber technologies. This technique obviates the need for full device fabrication to get feedback on optoelectronic quality of PV absorber layers and has expedited materials exploration. We then use this absorption model to evaluate the thermodynamic losses due to different band tail cases and estimate tail losses in Cu 2ZnSn(S,Se)4 (CZTSSe). The effect of sub-bandgap absorption on PL quantum yield (PLQY) and voltage is elucidated, and new analysis techniques for extracting VOC from PLQY are validated that reduce computation time and provide us even faster feedback on material quality. We then use PL imaging to develop a mechanism describing the degradation of solution-processed CH3NH3PbI3 films under applied bias and illumination.

Catalyst and processing effects on metal-assisted chemical etching for the production of highly porous GaN

NASA Astrophysics Data System (ADS)

Geng, Xuewen; Duan, Barrett K.; Grismer, Dane A.; Zhao, Liancheng; Bohn, Paul W.

2013-06-01

Metal-assisted chemical etching is a facile method to produce micro-/nanostructures in the near-surface region of gallium nitride (GaN) and other semiconductors. Detailed studies of the production of porous GaN (PGaN) using different metal catalysts and GaN doping conditions have been performed in order to understand the mechanism by which metal-assisted chemical etching is accomplished in GaN. Patterned catalysts show increasing metal-assisted chemical etching activity to n-GaN in the order Ag < Au < Ir < Pt. In addition, the catalytic behavior of continuous films is compared to discontinuous island films. Continuous metal films strongly shield the surface, hindering metal-assisted chemical etching, an effect which can be overcome by using discontinuous films or increasing the irradiance of the light source. With increasing etch time or irradiance, PGaN morphologies change from uniform porous structures to ridge and valley structures. The doping type plays an important role, with metal-assisted chemical etching activity increasing in the order p-GaN < intrinsic GaN < n-GaN. Both the catalyst identity and the doping type effects are explained by the work functions and the related band offsets that affect the metal-assisted chemical etching process through a combination of different barriers to hole injection and the formation of hole accumulation/depletion layers at the metal-semiconductor interface.

Design and Calibration of a X-Ray Millibeam

DTIC Science & Technology

2005-12-01

developed for use in Fricke dosimetry , parallel-plate ionization chambers, Lithium Fluoride thermoluminescent dosimetry ( TLD ), and EBT GafChromic...thermoluminescent dosimetry ( TLD ), and EBT GafChromic film to characterize the spatial distribution and accuracy of the doses produced by the Faxitron. A...absorbed dose calibration factors for use in Fricke dosimetry , parallel-plate ionization chambers, Lithium Fluoride (LiF) TLD , and EBT GafChromic film. The

Durable Corrosion and Ultraviolet-Resistant Silver Mirror

DOEpatents

Jorgensen, G. J.; Gee, R.

2006-01-24

A corrosion and ultra violet-resistant silver mirror for use in solar reflectors; the silver layer having a film-forming protective polymer bonded thereto, and a protective shield overlay comprising a transparent multipolymer film that incorporates a UV absorber. The corrosion and ultraviolet resistant silver mirror retains spectral hemispherical reflectance and high optical clarity throughout the UV and visible spectrum when used in solar reflectors.

Characterization of diamond thin films and related materials

NASA Astrophysics Data System (ADS)

McKindra, Travis Kyle

Thin carbon films including sputtered deposited graphite and CO 2 laser-assisted combustion-flame deposited graphite and diamond thin films were characterized using optical and electron microscopy, X-ray diffraction and micro-Raman spectroscopy. Amorphous carbon thin films were deposited by DC magnetron sputtering using Ar/O2 gases. The film morphology changed with the oxygen content. The deposition rate decreased as the amount of oxygen increased due to oxygen reacting with the growing film. The use of oxygen in the working gas enhanced the crystalline nature of the films. Graphite was deposited on WC substrates by a CO2 laser-assisted O2/C2H2 combustion-flame method. Two distinct microstructural areas were observed; an inner core of dense material surrounded by an outer shell of lamellar-like material. The deposits were crystalline regardless of the laser power and deposition times of a few minutes. Diamond films were deposited by a CO2 laser-assisted O 2/C2H2/C2H4 combustion-flame method with the laser focused parallel to the substrate surface. The laser enhanced diamond growth was most pronounced when deposited with a 10.532 microm CO2 laser wavelength tuned to the CH2-wagging vibrational mode of the C2H4 molecule. Nucleation of diamond thin films deposited with and without using a CO 2 laser-assisted combustion-flame process was investigated. With no laser there was nucleation of a sub-layer of grains followed by irregular grain growth. An untuned laser wavelength yielded nucleation of a sub-layer then columnar grain growth. The 10.532 microm tuned laser wavelength caused growth of columnar grains.

Design and fabrication of absorber coupled TES microbolometers on continuous silicon-nitride windows.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, C. L.; Carlstrom, J. E.; Datesman, A.

2008-04-01

The implementation of TES based microbolometer arrays will achieve unprecedented sensitivities for mm and sub-mm astronomy through fabrication of large format arrays and improved linearity and stability arising from strong electro-thermal feedback. We report on progress in developing TES microbolometers using Mo/Au thin films and Au absorbing structures. We present measurements of suppressing the thermal conductance through the etching of features on a continuous Silicon-Nitride window.

Tissue Adhesives for Battlefield Hemorrhage Control

DTIC Science & Technology

1996-04-01

extremely high bioburden it is felt that a rapid elution of the CHX or antimicrobial could be advantages. It is this rapid dumping of the 8000 Mw film...absorbance of each test article solution was determined spectrophotometrically at 545 nm. Similarly, absorbances were recorded for the positive...used to calculate percent hemolysis for the test article . Results showed 0.0% hemolysis for both test #1 and test #2, with a mean hemolysis of 0.0

An educational intervention to change planned behavior concerning midwife-assisted out-of-hospital childbirth.

PubMed

Hans, Jason D; Kimberly, Claire

2011-01-01

'The Business of Being Born' is a documentary film that reviews the history, economics, and culture of birth in the United States, with an emphasis on viewing low-risk birth as a natural and reasonably safe experience that does not require medical intervention. A nonequivalent control group design with 468 American university students was used to examine the potential of 'The Business of Being Born' for changing attitudes toward, and planned behavior concerning, midwife-assisted out-of-hospital childbirth. Viewing the film had a large positive effect on planned behavior concerning midwife-assisted out-of-hospital childbirth. Rationales for planned behaviors indicated that trust and safety concerns accounted for the appeal of physician-assisted hospital childbirth over midwife-assisted out-of-hospital childbirth, but that viewing the film substantially tempered these concerns vis-à-vis midwife-assisted out-of-hospital childbirth among a large portion of participants. The results indicate that 'The Business of Being Born' can increase awareness of and support for the midwifery profession, and that these changes may result in increased demand for midwifery services. However, proactive efforts must be taken to ensure that the film reaches its target audience. © 2011 by the American College of Nurse-Midwives.

Optical, electrical properties and structural characterization of ZnO:rGO based photodetector

NASA Astrophysics Data System (ADS)

Nath, Debarati; Mandal, S. K.; Deb, Debajit; Rakshit, J. K.; Dey, P.; Roy, J. N.

2018-04-01

Pure ZnO and ZnO:rGO composite films are prepared by sol-gel process and the effect of reduced graphene oxide(rGO) on structural, optical and electrical properties of the film are studied. UV-visspectrum shows that composite film exhibit similar optical absorbance property as pure ZnOfilm. Band gap of the film is changed from 3.32 to 3.21 eV by incorporation of rGO. From current-voltage curve it can be observed that photo current is increased significantly in composite film under red laser light illumination. This result suggests that conduction mechanism in composite film is dominated by rGO. Nyquist plot of both films show only one semicircle behavior in measured frequency range, which may be attributed to grain boundaries effects in the composite.

Device and method for luminescence enhancement by resonant energy transfer from an absorptive thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akselrod, Gleb M.; Bawendi, Moungi G.; Bulovic, Vladimir

Disclosed are a device and a method for the design and fabrication of the device for enhancing the brightness of luminescent molecules, nanostructures, and thin films. The device includes a mirror, a dielectric medium or spacer, an absorptive layer, and a luminescent layer. The absorptive layer is a continuous thin film of a strongly absorbing organic or inorganic material. The luminescent layer may be a continuous luminescent thin film or an arrangement of isolated luminescent species, e.g., organic or metal-organic dye molecules, semiconductor quantum dots, or other semiconductor nanostructures, supported on top of the absorptive layer.

Process for preparing group Ib-IIIa-VIa semiconducting films

DOEpatents

Birkmire, Robert W.; Schultz, Jerold M.; Marudachalam, Matheswaran; Hichri, Habib

1997-01-01

Methods are provided for the production of supported monophasic group I-III-VI semiconductor films. In the subject methods, a substrate is coated with group I and III elements and then contacted with a reactive group VI element containing atmosphere under conditions sufficient to produce a substrate coated with a composite of at least two different group I-III-IV alloys. The resultant composite coated substrate is then annealed in an inert atmosphere under conditions sufficient to convert the composite coating to a monophasic group I-III-VI semiconductor film. The resultant supported semiconductor films find use in photovoltaic applications, particularly as absorber layers in solar cells.

Process for preparing group Ib-IIIa-VIa semiconducting films

DOEpatents

Birkmire, R.W.; Schultz, J.M.; Marudachalam, M.; Hichri, H.

1997-10-07

Methods are provided for the production of supported monophasic group I-III-VI semiconductor films. In the subject methods, a substrate is coated with group I and III elements and then contacted with a reactive group VI element containing atmosphere under conditions sufficient to produce a substrate coated with a composite of at least two different group I-III-IV alloys. The resultant composite coated substrate is then annealed in an inert atmosphere under conditions sufficient to convert the composite coating to a monophasic group I-III-VI semiconductor film. The resultant supported semiconductor films find use in photovoltaic applications, particularly as absorber layers in solar cells. 4 figs.

Electrical and optical performance of transparent conducting oxide films deposited by electrostatic spray assisted vapour deposition.

PubMed

Hou, Xianghui; Choy, Kwang-Leong; Liu, Jun-Peng

2011-09-01

Transparent conducting oxide (TCO) films have the remarkable combination of high electrical conductivity and optical transparency. There is always a strong motivation to produce TCO films with good performance at low cost. Electrostatic Spray Assisted Vapor Deposition (ESAVD), as a variant of chemical vapour deposition (CVD), is a non-vacuum and low-cost deposition method. Several types of TCO films have been deposited using ESAVD process, including indium tin oxide (ITO), antimony-doped tin oxide (ATO), and fluorine doped tin oxide (FTO). This paper reports the electrical and optical properties of TCO films produced by ESAVD methods, as well as the effects of post treatment by plasma hydrogenation on these TCO films. The possible mechanisms involved during plasma hydrogenation of TCO films are also discussed. Reduction and etching effect during plasma hydrogenation are the most important factors which determine the optical and electrical performance of TCO films.

Promotion by humus-reducing bacteria for the degradation of UV254 absorbance in reverse-osmosis concentrates pretreated with O3-assisted UV-Fenton method.

PubMed

Xia, Jiaohui; Zhang, Hui; Ding, Shaoxuan; Li, Changyu; Ding, Jincheng; Lu, Jie

2017-07-12

The primary pollutants in reverse-osmosis concentrates (ROC) are the substances with the UV absorbance at 254 nm (UV 254 ), which is closely related to humic substances that can be degraded by humus-reducing bacteria. This work studied the degradation characteristics of humus-reducing bacteria in ROC treatment. The physiological and biochemical characteristics of humus-reducing bacteria were investigated, and the effects of pH values and electron donors on the reduction of humic analog, antraquinone-2, 6-disulfonate were explored to optimize the degradation. Furthermore, the O 3 -assisted UV-Fenton method was applied for the pretreatment of ROC, and the degradation of UV 254 absorbance was apparently promoted with their removal rate, reaching 84.2% after 10 days of degradation by humus-reducing bacteria.

Electromagnetic wave absorbing properties of amorphous carbon nanotubes.

PubMed

Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

2014-07-10

Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7-50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was -25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at -10 dB was up to 5.8 GHz within the frequency range of 2-18 GHz.

Broadband planar multilayered absorbers tuned by VO2 phase transition

NASA Astrophysics Data System (ADS)

Peng, Hao; Ji, Chunhui; Lu, Lulu; Li, Zhe; Li, Haoyang; Wang, Jun; Wu, Zhiming; Jiang, Yadong; Xu, Jimmy; Liu, Zhijun

2017-08-01

The metal-insulator transition makes vanadium dioxide an attractive material for developing reconfigurable optoelectronic components. Here we report on dynamically tunable broadband absorbers consisting of planar multilayered thin films. By thermally triggering the phase transition of vanadium dioxide, the effective impedance of multilayered structures is tuned in or out of the condition of impedance matching to free-space, leading to switchable broadband absorptions. Two types of absorbers are designed and demonstrated by using either the insulating or metallic state of vanadium dioxide at the impedance matched condition. The planar multilayered absorbers exhibit tunable absorption bands over the wavelength ranges of 5-9.3 μm and 3.9-8.2 μm, respectively. A large modulation depth up to 88% is measured. The demonstrated broadband absorbance tunability is of potential interest for reconfigurable bolometric sensing, camouflaging, and modulation of mid-infrared lights.

Nanofibrous membrane-based absorption refrigeration system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isfahani, RN; Sampath, K; Moghaddam, S

2013-12-01

This paper presents a study on the efficacy of highly porous nanofibrous membranes for application in membrane-based absorbers and desorbers. Permeability studies showed that membranes with a pore size greater than about one micron have a sufficient permeability for application in the absorber heat exchanger. Membranes with smaller pores were found to be adequate for the desorber heat exchanger. The membranes were implemented in experimental membrane-based absorber and desorber modules and successfully tested. Parametric studies were conducted on both absorber and desorber processes. Studies on the absorption process were focused on the effects of water vapor pressure, cooling water temperature,more » and the solution velocity on the absorption rate. Desorption studies were conducted on the effects of wall temperature, vapor and solution pressures, and the solution velocity on the desorption rate. Significantly higher absorption and desorption rates than in the falling film absorbers and desorbers were achieved. Published by Elsevier Ltd.« less

First principles calculations of point defect diffusion in CdS buffer layers: Implications for Cu(In,Ga)(Se,S){sub 2} and Cu{sub 2}ZnSn(Se,S){sub 4}-based thin-film photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varley, J. B.; Lordi, V.; He, X.

2016-01-14

We investigate point defects in CdS buffer layers that may arise from intermixing with Cu(In,Ga)Se{sub 2} (CIGSe) or Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) absorber layers in thin-film photovoltaics (PV). Using hybrid functional calculations, we characterize the migration barriers of Cu, In, Ga, Se, Sn, Zn, Na, and K impurities and assess the activation energies necessary for their diffusion into the bulk of the buffer. We find that Cu, In, and Ga are the most mobile defects in CIGS-derived impurities, with diffusion expected to proceed into the buffer via interstitial-hopping and cadmium vacancy-assisted mechanisms at temperatures ∼400 °C. Cu is predicted to stronglymore » favor migration paths within the basal plane of the wurtzite CdS lattice, which may facilitate defect clustering and ultimately the formation of Cu-rich interfacial phases as observed by energy dispersive x-ray spectroscopic elemental maps in real PV devices. Se, Zn, and Sn defects are found to exhibit much larger activation energies and are not expected to diffuse within the CdS bulk at temperatures compatible with typical PV processing temperatures. Lastly, we find that Na interstitials are expected to exhibit slightly lower activation energies than K interstitials despite having a larger migration barrier. Still, we find both alkali species are expected to diffuse via an interstitially mediated mechanism at slightly higher temperatures than enable In, Ga, and Cu diffusion in the bulk. Our results indicate that processing temperatures in excess of ∼400 °C will lead to more interfacial intermixing with CdS buffer layers in CIGSe devices, and less so for CZTSSe absorbers where only Cu is expected to significantly diffuse into the buffer.« less

Thin film solar cells: research in an industrial perspective.

PubMed

Edoff, Marika

2012-01-01

Electricity generation by photovoltaic conversion of sunlight is a technology in strong growth. The thin film technology is taking market share from the dominant silicon wafer technology. In this article, the market for photovoltaics is reviewed, the concept of photovoltaic solar energy conversion is discussed and more details are given about the present technological limitations of thin film solar cell technology. Special emphasis is given for solar cells which employ Cu(In,Ga)Se(2) and Cu(2)ZnSn(S,Se)(4) as the sunlight-absorbing layer.

Effects of FeCl3 additives on optical parameters of PVA

NASA Astrophysics Data System (ADS)

Latif, Duha M. A.; Chiad, Sami S.; Erhayief, Muhssen S.; Abass, Khalid H.; Habubi, Nadir F.; Hussin, Hadi A.

2018-05-01

PVA doped FeCl3 have been deposited utilizing casting technique. Absorption spectrum was registered in the wavelengths (300-900 nm) utilizing UV-Visible spectrophotometer. Optical constants behavior such as, absorbance, absorption coefficient, and skin depth were studied. It was found these parameters were increased as Fe content increase. While the extinction coefficient and optical conductivity was decreased. The energy gap of PVA-Fe films were decreased from 4 eV for the PVA film to 3.5 eV for the PVA: 4 % Fe film.

Plasma-assisted physical vapor deposition surface treatments for tribological control

NASA Technical Reports Server (NTRS)

Spalvins, Talivaldis

1990-01-01

In any mechanical or engineering system where contacting surfaces are in relative motion, adhesion, wear, and friction affect reliability and performance. With the advancement of space age transportation systems, the tribological requirements have dramatically increased. This is due to the optimized design, precision tolerance requirements, and high reliability expected for solid lubricating films in order to withstand hostile operating conditions (vacuum, high-low temperatures, high loads, and space radiation). For these problem areas the ion-assisted deposition/modification processes (plasma-based and ion beam techniques) offer the greatest potential for the synthesis of thin films and the tailoring of adherence and chemical and structural properties for optimized tribological performance. The present practices and new approaches of applying soft solid lubricant and hard wear resistant films to engineering substrates are reviewed. The ion bombardment treatments have increased film adherence, lowered friction coefficients, and enhanced wear life of the solid lubricating films such as the dichalcogenides (MoS2) and the soft metals (Au, Ag, Pb). Currently, sputtering is the preferred method of applying MoS2 films; and ion plating, the soft metallic films. Ultralow friction coefficients (less than 0.01) were achieved with sputtered MoS2. Further, new diamond-like carbon and BN lubricating films are being developed by using the ion assisted deposition techniques.

Influences of the residual argon gas and thermal annealing on Ta2O5 and SiO2 thin film filters

NASA Astrophysics Data System (ADS)

Liu, Wen-Jen; Chen, Chih-Min; Lai, Yin-Chieh

2005-04-01

Ion beam assisted deposition (IBAD) technique had widely used for improving stacking density and atomic mobility of thin films in many applications, especially adopted in optical film industries. Tantalum pentaoxide (Ta2O5) and silicon oxides (SiO2) optical thin films were deposited on the quartz glass substrate by using argon ion beam assisted deposition, and the influences of the residual argon gas and thermal annealing processes on the optical property, stress, compositional and microstructure evolution of the thin films were investigated in this study. Ta2O5 thin films were analyzed by XPS indicated that the ratio value of oxygen to tantalum was insufficient, at the same time, the residual argon gas in the thin films might result in film and device instabilities. Adopting oxygen-thermal annealing treatment at the temperature of 425°C, the thin films not only decreased the residual argon gas and the surface roughness, but also provided the sufficient stoichiometric ratio. Simultaneously, microstructure examination indicated few nano-crystallized structures and voids existed in Ta2O5 thin films, and possessed reasonable refractive index and lower extinction coefficient. By the way, we also suggested the IBAD system using the film compositional gas ion beam to replace the argon ion beam for assisting deposited optical films. The designed (HL)6H6LH(LH)6 multi-layers indicated higher insertion loss than the designed (HL)68H(LH)6 multi-layers. Therefore, using the high refractive index as spacer material represented lower insertion loss.

Laser assisted bioprinting using a femtosecond laser with and without a gold transductive layer: a parametric study

NASA Astrophysics Data System (ADS)

Desrus, H.; Chassagne, B.; Catros, S.; Artiges, C.; Devillard, R.; Petit, S.; Deloison, F.; Fricain, J. C.; Guillemot, F.; Kling, R.

2016-03-01

Experimental results of femtosecond Laser Assisted Bioprinting (LAB) are reported on. Two set-up, used to print different model bioinks and keratinocytes cells line HaCaT, were studied: first one was using a femtosecond laser with low pulse energy and an absorbing gold layer, whereas the second one used high pulse energy enabling the removal of the absorbing layer. Printed drop diameter and resulting height of the bioink jet are then quantified as a function of the LAB parameters such as laser energy, focus spot location or numerical aperture.

Peel-and-Stick: Mechanism Study for Efficient Fabrication of Flexible/Transparent Thin-film Electronics

NASA Astrophysics Data System (ADS)

Lee, Chi Hwan; Kim, Jae-Han; Zou, Chenyu; Cho, In Sun; Weisse, Jeffery M.; Nemeth, William; Wang, Qi; van Duin, Adri C. T.; Kim, Taek-Soo; Zheng, Xiaolin

2013-10-01

Peel-and-stick process, or water-assisted transfer printing (WTP), represents an emerging process for transferring fully fabricated thin-film electronic devices with high yield and fidelity from a SiO2/Si wafer to various non-Si based substrates, including papers, plastics and polymers. This study illustrates that the fundamental working principle of the peel-and-stick process is based on the water-assisted subcritical debonding, for which water reduces the critical adhesion energy of metal-SiO2 interface by 70 ~ 80%, leading to clean and high quality transfer of thin-film electronic devices. Water-assisted subcritical debonding is applicable for a range of metal-SiO2 interfaces, enabling the peel-and-stick process as a general and tunable method for fabricating flexible/transparent thin-film electronic devices.

Peel-and-stick: mechanism study for efficient fabrication of flexible/transparent thin-film electronics.

PubMed

Lee, Chi Hwan; Kim, Jae-Han; Zou, Chenyu; Cho, In Sun; Weisse, Jeffery M; Nemeth, William; Wang, Qi; van Duin, Adri C T; Kim, Taek-Soo; Zheng, Xiaolin

2013-10-10

Peel-and-stick process, or water-assisted transfer printing (WTP), represents an emerging process for transferring fully fabricated thin-film electronic devices with high yield and fidelity from a SiO2/Si wafer to various non-Si based substrates, including papers, plastics and polymers. This study illustrates that the fundamental working principle of the peel-and-stick process is based on the water-assisted subcritical debonding, for which water reduces the critical adhesion energy of metal-SiO2 interface by 70 ~ 80%, leading to clean and high quality transfer of thin-film electronic devices. Water-assisted subcritical debonding is applicable for a range of metal-SiO2 interfaces, enabling the peel-and-stick process as a general and tunable method for fabricating flexible/transparent thin-film electronic devices.

Sapphire substrate-induced effects in VO2 thin films grown by oxygen plasma-assisted pulsed laser deposition

NASA Astrophysics Data System (ADS)

Skuza, J. R.; Scott, D. W.; Pradhan, A. K.

2015-11-01

We investigate the structural and electronic properties of VO2 thin films on c-plane sapphire substrates with three different surface morphologies to control the strain at the substrate-film interface. Only non-annealed substrates with no discernible surface features (terraces) provided a suitable template for VO2 film growth with a semiconductor-metal transition (SMT), which was much lower than the bulk transition temperature. In addition to strain, oxygen vacancy concentration also affects the properties of VO2, which can be controlled through deposition conditions. Oxygen plasma-assisted pulsed laser deposition allows favorable conditions for VO2 film growth with SMTs that can be easily tailored for device applications.

Growth and characterization of EDTA assisted CBD-CdS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumarage, W. G. C.; Wijesundera, R. P.; Seneviratne, V. A.

2017-10-01

Chemical bath deposition of CdS (CBD-CdS) thin films with the assistance of a cationic surfactant, ethylenediamine tetraacetic acid (EDTA), is reported in this work. Also the EDTA treated CdS thin films are compared with that of conventional CBD-CdS. Fabricated thin, compact, uniform and adherent EDTA treated CdS films show enhanced effective surface area and roughness compared to conventional CBD-CdS. The grazing incidence x-ray diffraction analysis shows all the fabricated CdS films are hexagonally crystallized. EDTA-treated CdS films show excellent photo activity compared to conventional CBDCdS. The flat band potential (Vfb) value was found to be tunable with EDTA concentration.

Absorber Materials for Transition-Edge Sensor X-ray Microcalorimeters

NASA Technical Reports Server (NTRS)

Brown, Ari-David; Bandler, Simon; Brekosky, Regis; Chervenak, James; Figueroa-Feliciano, Enectali; Finkbeiner, Fred; Sadleir, Jack; Iyomoto, Naoko; Kelley, Richard; Kilbourne, Caroline;

Effect of reactive monomer on PS-b-P2VP film.

PubMed

Kim, H J; Shin, D M

2014-08-01

Poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP) lamellar film which is hydrophobic block-hydrophilic polyelectrolyte block polymer of 52 kg/mol-b-57 kg/mol and PS-b-P2VP film with reactive monomer (RM257) were prepared for photonic gel films. The lamellar stacks, which is alternating layer of hydrophilic and hydrophobic moiety of PS-b-P2VP, were obtained by exposing the spin coated film under chloroform vapor. The lamellar films were quaternized with 5 wt% of iodomethane diluted by n-hexane. We reported about the influence of reactive monomer on those photonic gel films. Added reactive monomer photonic gel film had higher absorbance than pure photonic gel films. As a result the photonic gel film with RM had more clear color. The lamellar films were swollen by DI water, ethanol (aq) and calcium carbonate solution. The band gaps of the lamellar films were drastically shifted to longer wavelength swollen by calcium carbonate solution. And the lamellar films were shifted to shorter wave length swollen by ethanol. So each lamellar film showed different color.

Vapor deposition of thin films

DOEpatents

Smith, David C.; Pattillo, Stevan G.; Laia, Jr., Joseph R.; Sattelberger, Alfred P.

1992-01-01

A highly pure thin metal film having a nanocrystalline structure and a process of preparing such highly pure thin metal films of, e.g., rhodium, iridium, molybdenum, tungsten, rhenium, platinum, or palladium by plasma assisted chemical vapor deposition of, e.g., rhodium(allyl).sub.3, iridium(allyl).sub.3, molybdenum(allyl).sub.4, tungsten(allyl).sub.4, rhenium(allyl).sub.4, platinum(allyl).sub.2, or palladium(allyl).sub.2 are disclosed. Additionally, a general process of reducing the carbon content of a metallic film prepared from one or more organometallic precursor compounds by plasma assisted chemical vapor deposition is disclosed.

Optical characterization of Mg-doped ZnO thin films deposited by RF magnetron sputtering technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Satyendra Kumar; Tripathi, Shweta; Hazra, Purnima

2016-05-06

This paper reports the in-depth analysis on optical characteristics of magnesium (Mg) doped zinc oxide (ZnO) thin films grown on p-silicon (Si) substrates by RF magnetron sputtering technique. The variable angle ellipsometer is used for the optical characterization of as-deposited thin films. The optical reflectance, transmission spectra and thickness of as-deposited thin films are measured in the spectral range of 300-800 nm with the help of the spectroscopic ellipsometer. The effect of Mg-doping on optical parameters such as optical bandgap, absorption coefficient, absorbance, extinction coefficient, refractive Index and dielectric constant for as-deposited thin films are extracted to show its application inmore » optoelectronic and photonic devices.« less

Influence of vacuum annealing on the properties of Cu2SnS3 thin films using low cost ultrasonic spray pyrolysis

NASA Astrophysics Data System (ADS)

Rahaman, Sabina; Sunil, M. Anantha; Shaik, Habibuddin; Ghosh, Kaustab

2018-05-01

Deposition of Cu2SnS3 (CTS) thin films is successfully carried out on soda lime glass substrate using low cost ultrasonic spray pyrolysis technique. Vacuum annealing of CTS films is carried out at different temperatures 350°C, 400°C and 450°C. The present work is to study the effect of annealing temperature on the crystal structure, surface morphology and optical properties of CTS thin films. Structural studies confirm the formation of CTS phase. Raman analysis is carried out to study presence of defects with annealing temperature. Optical studies confirm that film prepared at 450°C temperature is suitable as absorber material for photovoltaic applications.

Correlation of film thickness to optical band gap of Sol-gel derived Ba0.9Gd0.1TiO3 thin films for optoelectronic applications

NASA Astrophysics Data System (ADS)

Teh, Yen Chin; Saif, Ala'eddin A.; Azhar Zahid Jamal, Zul; Poopalan, Prabakaran

2017-11-01

Ba0.9Gd0.1TiO3 thin films have been fabricated on SiO2/Si and fused silica by sol-gel method. The films are prepared through a spin coating process and annealed at 900 °C to obtain crystallized films. The effect of film thickness on the microstructure and optical band gap has been investigated using X-ray diffractometer, atomic force microscope and ultraviolet-visible spectroscopy, respectively. XRD patterns confirm that the films crystallized with tetragonal phase perovskite structure. The films surface morphology is analysed through amplitude parameter analysis to find out that the grain size and surface roughness are increased with the increase of films thickness. The transmittance and absorbance spectra reveal that all films exhibit high absorption in UV region. The evaluated optical band gap is obtained in the range of 3.67 - 3.78 eV and is found to be decreased as the thickness increase.

Controlling the defects and transition layer in SiO2 films grown on 4H-SiC via direct plasma-assisted oxidation

PubMed Central

Kim, Dae-Kyoung; Jeong, Kwang-Sik; Kang, Yu-Seon; Kang, Hang-Kyu; Cho, Sang W.; Kim, Sang-Ok; Suh, Dongchan; Kim, Sunjung; Cho, Mann-Ho

2016-01-01

The structural stability and electrical performance of SiO2 grown on SiC via direct plasma-assisted oxidation were investigated. To investigate the changes in the electronic structure and electrical characteristics caused by the interfacial reaction between the SiO2 film (thickness ~5 nm) and SiC, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), density functional theory (DFT) calculations, and electrical measurements were performed. The SiO2 films grown via direct plasma-assisted oxidation at room temperature for 300s exhibited significantly decreased concentrations of silicon oxycarbides (SiOxCy) in the transition layer compared to that of conventionally grown (i.e., thermally grown) SiO2 films. Moreover, the plasma-assisted SiO2 films exhibited enhanced electrical characteristics, such as reduced frequency dispersion, hysteresis, and interface trap density (Dit ≈ 1011 cm−2 · eV−1). In particular, stress induced leakage current (SILC) characteristics showed that the generation of defect states can be dramatically suppressed in metal oxide semiconductor (MOS) structures with plasma-assisted oxide layer due to the formation of stable Si-O bonds and the reduced concentrations of SiOxCy species defect states in the transition layer. That is, energetically stable interfacial states of high quality SiO2 on SiC can be obtained by the controlling the formation of SiOxCy through the highly reactive direct plasma-assisted oxidation process. PMID:27721493

Selective Destruction of Protein Function by Chromophore-Assisted Laser Inactivation

NASA Astrophysics Data System (ADS)

Jay, Daniel G.

1988-08-01

Chromophore-assisted laser inactivation of protein function has been achieved. After a protein binds a specific ligand or antibody conjugated with malachite green (C.I. 42000), it is selectively inactivated by laser irradiation at a wavelength of light absorbed by the dye but not significantly absorbed by cellular components. Ligand-bound proteins in solution and on the surfaces of cells can be denatured without other proteins in the same samples being affected. Chromophore-assisted laser inactivation can be used to study cell surface phenomena by inactivating the functions of single proteins on living cells, a molecular extension of cellular laser ablation. It has an advantage over genetics and the use of specific inhibitors in that the protein function of a single cell within the organism can be inactivated by focusing the laser beam.

Template-assisted electrostatic spray deposition as a new route to mesoporous, macroporous, and hierarchically porous oxide films.

PubMed

Sokolov, S; Paul, B; Ortel, E; Fischer, A; Kraehnert, R

2011-03-01

A novel film coating technique, template-assisted electrostatic spray deposition (TAESD), was developed for the synthesis of porous metal oxide films and tested on TiO(2). Organic templates are codeposited with the titania precursor by electrostatic spray deposition and then removed during calcination. Resultant films are highly porous with pores casted by uniformly sized templates, which introduced a new level of control over the pore morphology for the ESD method. Employing the amphiphilic block copolymer Pluronic P123, PMMA latex spheres, or a combination of the two, mesoporous, macroporous, and hierarchically porous TiO(2) films are obtained. Decoupled from other coating parameters, film thickness can be controlled by deposition time or depositing multiple layers while maintaining the coating's structure and integrity.

A study on the enhancement of opto-electronic properties of CdS thin films: seed-assisted fabrication

NASA Astrophysics Data System (ADS)

Kumarage, W. G. C.; Wijesundera, R. P.; Seneviratne, V. A.; Jayalath, C. P.; Dassanayake, B. S.

2017-04-01

A novel method of fabricating chemical bath deposited CdS thin films (CBD-CdS) by using electrodeposited CdS (ED-CdS) as a seed layer is reported. The resulting thin, compact, uniform and adherent seed-assisted CdS films (ED/CBD-CdS) show enhanced effective surface area compared to both ED-CdS and CBD-CdS. The phase of these CdS films was determined to be hexagonal. The fabricated ED/CBD-CdS films show higher photoelectrochemical (PEC) cell efficiency than either ED-CdS and CBD-CdS thin films. Carrier concentration and flat band potential values for ED/CBD-CdS systems are also found to be superior compared to both ED-CdS and CBD-CdS systems.

Development and characterization of a three-dimensional radiochromic film stack dosimeter for megavoltage photon beam dosimetry.

PubMed

McCaw, Travis J; Micka, John A; DeWerd, Larry A

2014-05-01

Three-dimensional (3D) dosimeters are particularly useful for verifying the commissioning of treatment planning and delivery systems, especially with the ever-increasing implementation of complex and conformal radiotherapy techniques such as volumetric modulated arc therapy. However, currently available 3D dosimeters require extensive experience to prepare and analyze, and are subject to large measurement uncertainties. This work aims to provide a more readily implementable 3D dosimeter with the development and characterization of a radiochromic film stack dosimeter for megavoltage photon beam dosimetry. A film stack dosimeter was developed using Gafchromic(®) EBT2 films. The dosimeter consists of 22 films separated by 1 mm-thick spacers. A Virtual Water™ phantom was created that maintains the radial film alignment within a maximum uncertainty of 0.3 mm. The film stack dosimeter was characterized using simulations and measurements of 6 MV fields. The absorbed-dose energy dependence and orientation dependence of the film stack dosimeter were investigated using Monte Carlo simulations. The water equivalence of the dosimeter was determined by comparing percentage-depth-dose (PDD) profiles measured with the film stack dosimeter and simulated using Monte Carlo methods. Film stack dosimeter measurements were verified with thermoluminescent dosimeter (TLD) microcube measurements. The film stack dosimeter was also used to verify the delivery of an intensity-modulated radiation therapy (IMRT) procedure. The absorbed-dose energy response of EBT2 film differs less than 1.5% between the calibration and film stack dosimeter geometries for a 6 MV spectrum. Over a series of beam angles ranging from normal incidence to parallel incidence, the overall variation in the response of the film stack dosimeter is within a range of 2.5%. Relative to the response to a normally incident beam, the film stack dosimeter exhibits a 1% under-response when the beam axis is parallel to the film planes. Measured and simulated PDD profiles agree within a root-mean-square difference of 1.3%. In-field film stack dosimeter and TLD measurements agree within 5%, and measurements in the field penumbra agree within 0.5 mm. Film stack dosimeter and TLD measurements have expanded (k = 2) overall measurement uncertainties of 6.2% and 5.8%, respectively. Film stack dosimeter measurements of an IMRT dose distribution have 98% agreement with the treatment planning system dose calculation, using gamma criteria of 3% and 2 mm. The film stack dosimeter is capable of high-resolution, low-uncertainty 3D dose measurements, and can be readily incorporated into an existing film dosimetry program.

Conformal fabrication of colloidal quantum dot solids for optically enhanced photovoltaics.

PubMed

Labelle, André J; Thon, Susanna M; Kim, Jin Young; Lan, Xinzheng; Zhitomirsky, David; Kemp, Kyle W; Sargent, Edward H

2015-05-26

Colloidal quantum dots (CQD) are an attractive thin-film material for photovoltaic applications due to low material costs, ease of fabrication, and size-tunable band gap. Unfortunately, today they suffer from a compromise between light absorption and photocarrier extraction, a fact that currently prevents the complete harvest of incoming above-band-gap solar photons. We have investigated the use of structured substrates and/or electrodes to increase the effective light path through the active material and found that these designs require highly conformal application of the light-absorbing films to achieve the greatest enhancement. This conformality requirement derives from the need for maximal absorption enhancement combined with shortest-distance charge transport. Here we report on a means of processing highly conformal layer-by-layer deposited CQD absorber films onto microstructured, light-recycling electrodes. Specifically, we engineer surface hydrophilicity to achieve conformal deposition of upper layers atop underlying ones. We show that only with the application of conformal coating can we achieve optimal quantum efficiency and enhanced power conversion efficiency in structured-electrode CQD cells.

Simple diagnosis of HbA1c using the dual-plasmonic platform integrated with LSPR and SERS

NASA Astrophysics Data System (ADS)

Heo, Nam Su; Kwak, Cheol Hwan; Lee, Hoomin; Kim, Dongjoo; Lee, Sunmook; Kim, Gi-bum; Kwon, Soonjo; Kim, Woo Sik; Huh, Yun Suk

2017-07-01

A plasmonic active chip was designed with a transparent polymer film self-assembled with gold nanoparticles (AuNPs). In this study, we demonstrated the feasibility and sensitivity of biosensors by employing a plasmonic resonance technique. AuNPs are widely used as biosensing probes because they facilitate stable immobilization of biomolecules. Transparent polymer film facilitated measurement of changes in absorbance via transmitted light and analysis of Raman scattering via scattered light. The cysteine rich protein G and anti-HbA1c were sequentially conjugated to self-assembled AuNPs on the transparent polymer film to detect a target protein. HbA1c, which is used as an indicator for diabetes diagnosis, was selected for target protein detection. We confirmed the linearly increased absorbance values with increasing HbA1c level (3.19-14.0%) by LSPR detection. We also verified the linear increase in SERS intensity as the concentration of anti-Hb increased from 10 ng mL-1 to 1 μg mL-1 by analyzing the SERS spectra of Cy3 labeled anti-Hb added substrates.

Planar structured perovskite solar cells by hybrid physical chemical vapor deposition with optimized perovskite film thickness

NASA Astrophysics Data System (ADS)

Wei, Xiangyang; Peng, Yanke; Jing, Gaoshan; Cui, Tianhong

2018-05-01

The thickness of perovskite absorber layer is a critical parameter to determine a planar structured perovskite solar cell’s performance. By modifying the spin coating speed and PbI2/N,N-dimethylformamide (DMF) solution concentration, the thickness of perovskite absorber layer was optimized to obtain high-performance solar cells. Using a PbI2/DMF solution of 1.3 mol/L, maximum power conversion efficiency (PCE) of a perovskite solar cell is 15.5% with a perovskite film of 413 nm at 5000 rpm, and PCE of 14.3% was also obtained for a solar cell with a perovskite film of 182 nm thick. It is derived that higher concentration of PbI2/DMF will result in better perovskite solar cells. Additionally, these perovskite solar cells are highly uniform. In 14 sets of solar cells, standard deviations of 11 sets of solar cells were less than 0.50% and the smallest standard deviation was 0.25%, which demonstrates the reliability and effectiveness of hybrid physical chemical vapor deposition (HPCVD) method.

Buried homojunction in CdS/Sb2Se3 thin film photovoltaics generated by interfacial diffusion

NASA Astrophysics Data System (ADS)

Zhou, Ying; Li, Yang; Luo, Jiajun; Li, Dengbing; Liu, Xinsheng; Chen, Chao; Song, Huaibing; Ma, Jingyuan; Xue, Ding-Jiang; Yang, Bo; Tang, Jiang

2017-07-01

Antimony selenide (Sb2Se3) emerges as a very promising non-toxic absorber material for thin film photovoltaics, and most of the devices, either in the superstrate or substrate configuration, employed CdS as the buffer layer. Due to the peculiar one-dimensional crystal structure of Sb2Se3, severe interfacial diffusion would be expected. In this letter, the interfacial diffusion in CdS/Sb2Se3 photovoltaics was carefully characterized from a combined material and device physics characterization. The results indicated that a buried homojunction located deep inside the Sb2Se3 absorber layer due to Cd diffusion, instead of the apparent CdS/Sb2Se3 heterojunction, dictated charge separation and device performance in Sb2Se3 thin film solar cells. Cd diffusion converted p-type Sb2Se3 into n-type by introducing a donor level with an activation energy of 0.22 eV. Our studies deepen the understanding of Sb2Se3 photovoltaics and shed light on their further performance optimization.

Microfabrication of High Resolution X-ray Magnetic Calorimeters

NASA Astrophysics Data System (ADS)

Hsieh, Wen-Ting; Bandler, Simon R.; Kelly, Daniel P.; Porst, Jan P.; Rotzinger, Hannes; Seidel, George M.; Stevenson, Thomas R.

2009-12-01

Metallic magnetic calorimeter (MMC) is one of the most promising x-ray detector technologies for providing the very high energy resolution needed for future astronomical x-ray imaging spectroscopy. For this purpose, we have developed micro-fabricated 5×5 arrays of MMC of which each individual pixel has excellent energy resolution as good as 3.4 eV at 6 keV x-ray. Here we report on the fabrication techniques developed to achieve good resolution and high efficiency. These include: processing of a thin insulation layer for strong magnetic coupling between the AuEr sensor film and the niobium pick-up coil; production of overhanging absorbers for enhanced efficiency of x-ray absorption; fabrication on SiN membranes to minimize the effects on energy resolution from athermal phonon loss. We have also improved the deposition of the magnetic sensor film such that the film magnetization is nearly completely that is expected from the AuEr sputter target bulk material. In addition, we have included a study of a positional sensitive design, the Hydra design, which allows thermal coupling of four absorbers to a common MMC sensor and circuit.

Factors that affect the EVA encapsulant discoloration rate upon accelerated exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pern, F.J.

1994-12-31

Several factors that may affect the net discoloration rate of the ethylene-vinyl acetate (EVA) copolymer encapsulants used in crystalline-Si photovoltaic (c-Si PV) modules upon accelerated exposure have been investigated by employing UV-visible spectrophotometry, spectrocolorimetry, and fluorescence analysis. A number of laminated films, including the two typical EVA formulations, A9918 and 15295, were studied. The results indicate that the rate of EVA discoloration is affected by the (1) curing agent and curing conditions; (2) presence and concentration of curing-generated, UV-excitable chromophores; (3) UV light intensity; (4) loss rate of the UV absorber, Cyasorb UV 531; (5) lamination; (6) film thickness; andmore » (7) photobleaching rate due to the diffusion of air into the laminated films. In general, the loss rate of the UV absorber and the rate of discoloration from light yellow to brown follow a sigmoidal pattern. A reasonable correlation for net changes in transmittance at 420 nm, yellowness index, and fluorescence peak area (or intensity) ratio is obtained as the extent of EVA discoloration progressed.« less

Anti-Oxidative and Antibacterial Self-Healing Edible Polyelectrolyte Multilayer Film in Fresh-Cut Fruits.

PubMed

Liu, Xuefan; Han, Wei; Zhu, Yanxi; Xuan, Hongyun; Ren, Jiaoyu; Zhang, Jianhao; Ge, Liqin

2018-04-01

The consumption of fresh-cut fruits is limited because of the oxidation browning and pathogenic bacteria's growth on the fruit surface. Besides, crack of the fresh-keeping film may shorten the preservation time of fruit. In this work, polyelectrolyte multilayer (PEM) film was fabricated by layer-by-layer (LBL) electrostatic deposition method. The film was made by carboxy methylcellulose sodium (CMC) and chitosan (CS). The as-prepared PEM film had good anti-oxidative and antibacterial capability. It inhibited the growth of Gram-negative bacteria and the antibacterial rate was more than 95%. The stratified structure and linear increase of the absorbance in the film verified a linear increase of film thickness. The slight scratched film could self-heal rapidly after the stimulation of water whatever the layer number was. Moreover, the film could heal cracks whose width was far bigger than the thickness. The application of PEM film on fresh-cut apples showed that PEM film had good browning, weight loss and metabolic activity inhibition ability. These results showed that the PEM film is a good candidate as edible film in fresh-cut fruits applications.

High resolution Li depth profiling of solid state Li ion battery by TERD technique with high energy light ions

NASA Astrophysics Data System (ADS)

Morita, K.; Tsuchiya, B.; Ohnishi, J.; Yamamoto, T.; Iriyama, Y.; Tsuchida, H.; Majima, T.; Suzuki, K.

2018-07-01

Li depth profiles in Au/Si/LiPON/LCO/Au (LCO = LiCoO2, LiPON = Li3.3PO3.8N0.2) thin films battery under charging condition, prepared on self-supporting Al substrate, have been in situ measured by means of transmission elastic recoil detection (TERD) and Rutherford backscattering spectroscopy (RBS) techniques not only with 5.4 MeV He2+ ion beam without absorber, but also 9 MeV O4+ ion beam with Al absorber. In experiments with 5.4 MeV He2+, well-resolved step-wise TERD spectra have been observed, from which thickness and Li composition of constituent films of the battery are directly estimated. The Li transport from LCO to Si films through LiPON as well as return-back of Li from Si to LCO films and Li leakage into the Al substrate out of the battery system by over-charging under charging condition have been observed in the experiments both 5.4 MeV He2+ and 9 MeV O4+. The latter result indicates that these techniques are applicable to testing degradation of the battery performance by repetition of charging and discharging. Both results are compared in details with each other.

Supersensitization of CdS quantum dots with a near-infrared organic dye: toward the design of panchromatic hybrid-sensitized solar cells.

PubMed

Choi, Hyunbong; Nicolaescu, Roxana; Paek, Sanghyun; Ko, Jaejung; Kamat, Prashant V

2011-11-22

The photoresponse of quantum dot solar cells (QDSCs) has been successfully extended to the near-IR (NIR) region by sensitizing nanostructured TiO(2)-CdS films with a squaraine dye (JK-216). CdS nanoparticles anchored on mesoscopic TiO(2) films obtained by successive ionic layer adsorption and reaction (SILAR) exhibit limited absorption below 500 nm with a net power conversion efficiency of ~1% when employed as a photoanode in QDSC. By depositing a thin barrier layer of Al(2)O(3), the TiO(2)-CdS films were further modified with a NIR absorbing squaraine dye. Quantum dot sensitized solar cells supersensitized with a squariand dye (JK-216) showed good stability during illumination with standard global AM 1.5 solar conditions, delivering a maximum overall power conversion efficiency (η) of 3.14%. Transient absorption and pulse radiolysis measurements provide further insight into the excited state interactions of squaraine dye with SiO(2), TiO(2), and TiO(2)/CdS/Al(2)O(3) films and interfacial electron transfer processes. The synergy of combining semiconductor quantum dots and NIR absorbing dye provides new opportunities to harvest photons from different regions of the solar spectrum. © 2011 American Chemical Society

Light-Induced Buckles Localized by Polymeric Inks Printed on Bilayer Films.

PubMed

Park, Sungjune; Nallainathan, Umaash; Mondal, Kunal; Sen, Pratik; Dickey, Michael D

2018-04-16

Buckling instabilities generate microscale features in thin films in a facile manner. Buckles can form, for example, by heating a metal/polymer film stack on a rigid substrate. Thermal expansion differences of the individual layers generate compressive stress that causes the metal to buckle over the entire surface. The ability to dictate and confine the location of buckle formation can enable patterns with more than one length scale, including hierarchical patterns. Here, sacrificial "ink" patterned on top of the film stack localizes the buckles via two mechanisms. First, stiff inks suppress buckles such that only the non-inked regions buckle in response to infrared light. The metal in the non-inked regions absorbs the infrared light and thus gets sufficiently hot to induce buckles. Second, soft inks that absorb light get hot faster than the non-inked regions and promote buckling when exposed to visible light. The exposed metal in the non-inked regions reflects the light and thus never get sufficiently hot to induce buckles. This second method works on glass substrates, but not silicon substrates, due to the superior thermal insulation of glass. The patterned ink can be removed, leaving behind hierarchical patterns consisting of regions of buckles among non-buckled regions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Selenization Processes on CIGS Solar Cell Performance.

PubMed

Wu, C H; Wu, P W; Chen, J H; Kao, J Y; Hsu, C Y

2018-07-01

Cu(In, Ga)Se2 (CIGS) films were fabricated by a two-step process method using sputtering from Cu0.7Ga0.3 and In targets. The metallic precursor structures of In/CuGa/In were prepared, and CuGa film was adjusted to the thicknesses of 150, 200, 250 and 300 nm, in order to optimize the CIGS film. After selenization, three independent CIGS (112), CIGS (220/204) and CIGS (312/116) began to crystallize at ~280 °C and phase peaks continued growing until 560 °C. Experimental results showed that with a single stage selenization method, the excessive stoichiometry of the CIGS films was obtained. Using three sequential stages for the selenization process, with a annealing time of 20 min, the stoichiometry of the CIGS absorbers with the Cu/(In + Ga) and Ga/(In + Ga) showed atomic ratios of 0.94 and 0.34, respectively. The intensity of the (112) XRD diffraction peak became stronger, indicating an improvement in the crystallinity. Raman spectra of CIGS absorbers showed a main peak (174 cm-1) and two weak signals (212 and 231 cm-1). TEM image for electron diffraction pattern showed that the grains were randomly oriented. CIGS solar cell device prepared with a proper selenization, a maximum efficiency of 12.45% was obtained.

Chemical structural analysis of diamondlike carbon films: II. Raman analysis

NASA Astrophysics Data System (ADS)

Takabayashi, Susumu; Ješko, Radek; Shinohara, Masanori; Hayashi, Hiroyuki; Sugimoto, Rintaro; Ogawa, Shuichi; Takakuwa, Yuji

2018-02-01

The chemical structure of diamondlike carbon (DLC) films, synthesized by photoemission-assisted glow discharge, has been analyzed by Raman spectroscopy. Raman analysis in conjunction with the sp2 cluster model clarified the film structure. The sp2 clusters in DLC films synthesized at low temperature preferred various aliphatic structures. Sufficient argon-ion assist allowed for formation of less strained DLC films containing large amounts of hydrogen. As the synthesis temperature was increased, thermal desorption of hydrogen left carbon dangling bonds with active unpaired electrons in the films, and the reactions that followed created strained films containing aromatic sp2 clusters. In parallel, the desorption of methane molecules from the growing surface by chemisorption of hydrogen radicals prevented the action of argon ions, promoting internal strain of the films. However, in synthesis at very high temperature, where sp2 clusters are sufficiently dominant, the strain was dissolved gradually. In contrast, the DLC films synthesized at low temperature were more stable than other films synthesized at the same temperature because of stable hydrogen-carbon bonds in the films.

Nanoimprinted backside reflectors for a-Si:H thin-film solar cells: critical role of absorber front textures.

PubMed

Tsao, Yao-Chung; Fisker, Christian; Pedersen, Thomas Garm

2014-05-05

The development of optimal backside reflectors (BSRs) is crucial for future low cost and high efficiency silicon (Si) thin-film solar cells. In this work, nanostructured polymer substrates with aluminum coatings intended as BSRs were produced by positive and negative nanoimprint lithography (NIL) techniques, and hydrogenated amorphous silicon (a-Si:H) was deposited hereon as absorbing layers. The relationship between optical properties and geometry of front textures was studied by combining experimental reflectance spectra and theoretical simulations. It was found that a significant height variation on front textures plays a critical role for light-trapping enhancement in solar cell applications. As a part of sample preparation, a transfer NIL process was developed to overcome the problem of low heat deflection temperature of polymer substrates during solar cell fabrication.

Graphene Oxide saturable absorber for generating eye-safe Q-switched fiber laser

NASA Astrophysics Data System (ADS)

Rosol, A. H. A.; Jusoh, Z.; Rahman, H. A.; Rusdi, M. F. M.; Harun, S. W.; Latiff, A. A.

2017-06-01

This paper reports the generation of Q-switched fiber laser using thulium doped fiber (TDF) as a gain medium and graphene oxide (GO) as a saturable absorber (SA). The GO powder is embedded into polyvinyl alcohol (PVA) to form an SA film based on a drop-casting technique. GO-SA film is sandwiched between two fiber connectors and tighten by FC adapter before it is incorporated into an TDF laser cavity for Q-switching pulse generation. At 344 mW pump level, a stable Q-switching regime presence at 1943 nm with a 3-dB spectral bandwidth of 9 nm. The maximum repetition rate, pulse width, and pulse energy are at 25 kHz, 4.2 µs, and 0.68 µJ, respectively. All finding results are comparable with other reported pulse fiber lasers.

Optimization of material/device parameters of CdTe photovoltaic for solar cells applications

NASA Astrophysics Data System (ADS)

Wijewarnasuriya, Priyalal S.

2016-05-01

Cadmium telluride (CdTe) has been recognized as a promising photovoltaic material for thin-film solar cell applications due to its near optimum bandgap of ~1.5 eV and high absorption coefficient. The energy gap is near optimum for a single-junction solar cell. The high absorption coefficient allows films as thin as 2.5 μm to absorb more than 98% of the above-bandgap radiation. Cells with efficiencies near 20% have been produced with poly-CdTe materials. This paper examines n/p heterostructure device architecture. The performance limitations related to doping concentrations, minority carrier lifetimes, absorber layer thickness, and surface recombination velocities at the back and front interfaces is assessed. Ultimately, the paper explores device architectures of poly- CdTe and crystalline CdTe to achieve performance comparable to gallium arsenide (GaAs).

Photovoltaic Properties of Selenized CuGa/In Films with Varied Compositions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muzzillo, Christopher P.; Mansfield, Lorelle M.; Ramanathan, Kannan

2016-11-21

Thin CuGa/In films with varied compositions were deposited by co-evaporation and then selenized in situ with evaporated selenium. The selenized Cu(In, Ga)Se2 absorbers were used to fabricate 390 solar cells. Cu/(Ga+In) and Ga/(Ga+In) (Cu/III and Ga/III) were independently varied, and photovoltaic performance was optimal at Cu/III of 77-92% for all Ga/III compositions studied (Ga/III ~ 30, 50, and 70%). The best absorbers at each Ga/III composition were characterized with time-resolved photoluminescence, scanning electron microscopy, and secondary ion mass spectrometry, and devices were studied with temperature-dependent current density-voltage, light and electrical biased quantum efficiency, and capacitance-voltage. The best cells with Ga/IIImore » ~ 30, 50, and 70% had efficiencies of 14.5, 14.4, and 12.2% and maximum power temperature coefficients of -0.496, -0.452, and -0.413%/degrees C, respectively. This resulted in the Ga/III ~ 50% champion having the highest efficiency at temperatures greater than 40 degrees C, making it the optimal composition for practical purposes. This optimum is understood as a result of the absorber's band gap grading- where minimum band gap dominates short-circuit current density, maximum space charge region band gap dominates open-circuit voltage, and average absorber band gap dominates maximum power temperature coefficient.« less

Green, stable and earth abundant ionic PV absorbers based on chalcogenide perovskite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, Hao

Searching for inexpensive, environment-friendly, and air-stable absorber materials for thin film solar cells has become a key thrust of PV research. Supported by this one-year award, the UB-RPI team aims to develop a novel class of semiconductors — chalcogenide perovskites. Sharing some similarities to the widely researched halide perovskites, and unlike most conventional semiconductors, the chalcogenide perovskites are strongly ionic. Such characteristics is expected to provide intrinsic defect properties favorable for charge transport in PV absorbers. In this one-year project, we confirmed structural stability of the BaZrS3 material through high pressure Raman studies. We find no evidence that the perovskitemore » structure of BaZrS3 undergoes any phase changes under hydrostatic pressure to at least 8.9 GPa. Our results indicate the robust structural stability of BaZrS3, and suggest cation alloying as a viable approach for band-gap engineering for photovoltaic and other applications. We also achieved reduced band gap to 1.45 eV by Ti-alloying of BaZrS3, which is close to the optimal value for a single junction solar cell. We further synthesized BaZrS3 thin films with desired crystal structure and band gap. The optical absorption is high as expected. The carrier mobility is moderate. The high processing temperature limits its ability for device integration. We are working on deposition of chalcogenide perovskite thin films using molecular beam epitaxy.« less

2D Homologous Perovskites as Light-Absorbing Materials for Solar Cell Applications.

PubMed

Cao, Duyen H; Stoumpos, Constantinos C; Farha, Omar K; Hupp, Joseph T; Kanatzidis, Mercouri G

2015-06-24

We report on the fabrication and properties of the semiconducting 2D (CH3(CH2)3NH3)2(CH3NH3)(n-1)Pb(n)I(3n+1) (n = 1, 2, 3, and 4) perovskite thin films. The band gaps of the series decrease with increasing n values, from 2.24 eV (CH3(CH2)3NH3)2PbI4 (n = 1) to 1.52 eV CH3NH3PbI3 (n = ∞). The compounds exhibit strong light absorption in the visible region, accompanied by strong photoluminescence at room temperature, rendering them promising light absorbers for photovoltaic applications. Moreover, we find that thin films of the semi-2D perovskites display an ultrahigh surface coverage as a result of the unusual film self-assembly that orients the [Pb(n)I(3n+1)](-) layers perpendicular to the substrates. We have successfully implemented this 2D perovskite family in solid-state solar cells, and obtained an initial power conversion efficiency of 4.02%, featuring an open-circuit voltage (V(oc)) of 929 mV and a short-circuit current density (J(sc)) of 9.42 mA/cm(2) from the n = 3 compound. This result is even more encouraging considering that the device retains its performance after long exposure to a high-humidity environment. Overall, the homologous 2D halide perovskites define a promising class of stable and efficient light-absorbing materials for solid-state photovoltaics and other applications.

Controlled reflectance surfaces with film-coupled colloidal nanoantennas

PubMed Central

Moreau, Antoine; Ciraci, Cristian; Mock, Jack J.; Hill, Ryan T.; Wang, Qiang; Wiley, Benjamin J.; Chilkoti, Ashutosh; Smith, David R.

2013-01-01

Efficient and tunable absorption is essential for a variety of applications, such as the design of controlled emissivity surfaces for thermophotovoltaic devices1; tailoring of the infrared spectrum for controlled thermal dissipation2; and detector elements for imaging3. Metamaterials based on metallic elements are particularly efficient as absorbing media, because both the electrical and the magnetic properties of a metamaterial can be tuned by structured design4. To date, metamaterial absorbers in the infrared or visible range have been fabricated using lithographically patterned metallic structures2,5–9, making them inherently difficult to produce over large areas and hence reducing their applicability. We demonstrate here an extraordinarily simple method to create a metamaterial absorber by randomly adsorbing chemically synthesized silver nanocubes onto a nanoscale thick polymer spacer layer on a gold film –making no effort to control the spatial arrangement of the cubes on the film– and show that the film-coupled nanocubes provide a reflectance spectrum that can be tailored by varying the geometry. Each nanocube is the optical analog of the well-known grounded patch antenna, with a nearly identical local field structure that is modified by the plasmonic response of the metal dielectric function, and with an anomalously large absorption efficiency that can be partly attributed to an interferometric effect10. The absorptivity of large surface areas can be controlled using this method, at scales out of reach of lithographic approaches like e-beam lithography otherwise required to manipulate matter at the nanometer scale. PMID:23222613

Interfacial Engineering and Charge Carrier Dynamics in Extremely Thin Absorber Solar Cells

NASA Astrophysics Data System (ADS)

Edley, Michael

Photovoltaic energy is a clean and renewable source of electricity; however, it faces resistance to widespread use due to cost. Nanostructuring decouples constraints related to light absorption and charge separation, potentially reducing cost by allowing a wider variety of processing techniques and materials to be used. However, the large interfacial areas also cause an increased dark current which negatively affects cell efficiency. This work focuses on extremely thin absorber (ETA) solar cells that used a ZnO nanowire array as a scaffold for an extremely thin CdSe absorber layer. Photoexcited electrons generated in the CdSe absorber are transferred to the ZnO layer, while photogenerated holes are transferred to the liquid electrolyte. The transfer of photoexcited carriers to their transport layer competes with bulk recombination in the absorber layer. After charge separation, transport of charge carriers to their respective contacts must occur faster than interfacial recombination for efficient collection. Charge separation and collection depend sensitively on the dimensions of the materials as well as their interfaces. We demonstrated that an optimal absorber thickness can balance light absorption and charge separation. By treating the ZnO/CdSe interface with a CdS buffer layer, we were able to improve the Voc and fill factor, increasing the ETA cell's efficiency from 0.53% to 1.34%, which is higher than that achievable using planar films of the same material. We have gained additional insight into designing ETA cells through the use of dynamic measurements. Ultrafast transient absorption spectroscopy revealed that characteristic times for electron injection from CdSe to ZnO are less than 1 ps. Electron injection is rapid compared to the 2 ns bulk lifetime in CdSe. Optoelectronic measurements such as transient photocurrent/photovoltage and electrochemical impedance spectroscopy were applied to study the processes of charge transport and interfacial recombination. With these techniques, the extension of the depletion layer from CdSe into ZnO was determined to be vital to suppression of interfacial recombination. However, depletion of the ZnO also restricted the effective diffusion core for electrons and slowed their transport. Thus, materials and geometries should be chosen to allow for a depletion layer that suppresses interfacial recombination without impeding electron transport to the point that it is detrimental to cell performance. Thin film solar cells are another promising technology that can reduce costs by relaxing material processing requirements. CuInxGa (1-x)Se (CIGS) is a well studied thin film solar cell material that has achieved good efficiencies of 22.6%. However, use of rare elements raise concerns over the use of CIGS for global power production. CuSbS2 shares chemistry with CuInSe2 and also presents desirable properties for thin film absorbers such as optimal band gap (1.5 eV), high absorption coefficient, and Earth-abundant and non-toxic elements. Despite the promise of CuSbS2, direct characterization of the material for solar cell application is scarce in the literature. CuSbS2 nanoplates were synthesized by a colloidal hot-injection method at 220 °C in oleylamine. The CuSbS2 platelets synthesized for 30 minutes had dimensions of 300 nm by 400 nm with a thickness of 50 nm and were capped with the insulating oleylamine synthesis ligand. The oleylamine synthesis ligand provides control over nanocrystal growth but is detrimental to intercrystal charge transport that is necessary for optoelectronic device applications. Solid-state and solution phase ligand exchange of oleylamine with S2- were used to fabricate mesoporous films of CuSbS2 nanoplates for application in solar cells. Exchange of the synthesis ligand with S2- resulted in a two order of magnitude increase in 4-point probe conductivity. Photoexcited carrier lifetimes of 1.4 ns were measured by time-resolved terahertz spectroscopy, indicating potential for CuSbS2 as a solar cell absorber material.

Development of Superconducting Transition Edge Sensors Based on Electron-Phonon Decoupling

NASA Technical Reports Server (NTRS)

Jethava, Nikhil; Chervenak, James; Brown, Ari-David; Benford, Dominic; Kletetschka, Gunther; Mikula, Vilem; U-yen, Kongpop

2010-01-01

We have successfully fabricated a superconducting transition edge sensor (TES), bolometer that centers on the use of electron-phonon decoupling (EPD) for thermal isolation. We have selected a design approach that separates the two functions of far-infrared and THz radiative power absorption and temperature measurement, allowing separate optimization of the performance of each element. We have integrated molybdenum/gold (Mo/Au) bilayer TES and ion assisted thermally evaporated (IAE) bismuth (Bi) films as radiation absorber coupled to a low-loss microstripline from niobium (Nb) ground plane to a twin-slot antenna structure. The thermal conductance (G) and the time constant for the different geometry device have been measured. For one such device, the measured G is 1.16 x 10(exp -10) W/K (plus or minus 0.61 x 10(exp- 10) W/K) at 60 mK, which corresponds to noise equivalent power (NEP) = 1.65 X 10(exp -18)W/vHz and time constant of approximately 5 microseconds.

Iron-filled multi-walled carbon nanotubes for terahertz applications: effects of interfacial polarization, screening and anisotropy.

PubMed

Sedelnikova, O V; Korovin, E Yu; Dorozhkin, K V; Kanygin, M A; Arkhipov, V E; Shubin, Yu V; Zhuravlev, V A; Suslyaev, V I; Bulusheva, L G; Okotrub, A V

2018-04-27

Interface interactions in multicomponent nanoparticles can affect electromagnetic properties of an absorbing system. In this work, we investigate the electromagnetic response of multi-walled carbon nanotubes (MWCNTs) filled with iron-containing nanoparticles (ICNs) in the terahertz frequency range. MWCNTs with different iron content have been synthesized by aerosol-assisted catalytic chemical vapour deposition method from toluene containing a certain quantity of ferrocene used as a catalyst. According to the x-ray diffraction analysis, encapsulated ICNs were mainly in the form of iron carbide. Thin composite films were prepared from the iron-filled MWCNTs and polymethylmethacrylate (PMMA) by casting and stretching methods. The composites showed an enhanced permittivity and anisotropy in the transmittance spectra when iron content increased. This behaviour was related to the mechanism based on electrical conductivity and polarization of ICNs and ICN/MWCNT interfaces. Since terahertz field penetrates inside MWCNTs, the filling of their cavities can be a way of varying the electromagnetic properties of MWCNT-containing composites.

Iron-filled multi-walled carbon nanotubes for terahertz applications: effects of interfacial polarization, screening and anisotropy

NASA Astrophysics Data System (ADS)

Sedelnikova, O. V.; Korovin, E. Yu; Dorozhkin, K. V.; Kanygin, M. A.; Arkhipov, V. E.; Shubin, Yu V.; Zhuravlev, V. A.; Suslyaev, V. I.; Bulusheva, L. G.; Okotrub, A. V.

2018-04-01

Interface interactions in multicomponent nanoparticles can affect electromagnetic properties of an absorbing system. In this work, we investigate the electromagnetic response of multi-walled carbon nanotubes (MWCNTs) filled with iron-containing nanoparticles (ICNs) in the terahertz frequency range. MWCNTs with different iron content have been synthesized by aerosol-assisted catalytic chemical vapour deposition method from toluene containing a certain quantity of ferrocene used as a catalyst. According to the x-ray diffraction analysis, encapsulated ICNs were mainly in the form of iron carbide. Thin composite films were prepared from the iron-filled MWCNTs and polymethylmethacrylate (PMMA) by casting and stretching methods. The composites showed an enhanced permittivity and anisotropy in the transmittance spectra when iron content increased. This behaviour was related to the mechanism based on electrical conductivity and polarization of ICNs and ICN/MWCNT interfaces. Since terahertz field penetrates inside MWCNTs, the filling of their cavities can be a way of varying the electromagnetic properties of MWCNT-containing composites.

A Novel UV-Shielding and Transparent Polymer Film: When Bioinspired Dopamine-Melanin Hollow Nanoparticles Join Polymers.

PubMed

Wang, Yang; Su, Jing; Li, Ting; Ma, Piming; Bai, Huiyu; Xie, Yi; Chen, Mingqing; Dong, Weifu

2017-10-18

Ultraviolet (UV) light is known to be harmful to human health and cause organic materials to undergo photodegradation. In this Research Article, bioinspired dopamine-melanin solid nanoparticles (Dpa-s NPs) and hollow nanoparticles (Dpa-h NPs) as UV-absorbers were introduced to enhance the UV-shielding performance of polymer. First, Dpa-s NPs were synthesized through autoxidation of dopamine in alkaline aqueous solution. Dpa-h NPs were prepared by the spontaneous oxidative polymerization of dopamine solution onto polystyrene (PS) nanospheres template, followed by removal of the template. Poly(vinyl alcohol) (PVA)/Dpa nanocomposite films were subsequently fabricated by a simple casting solvent. UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of Dpa-s versus Dpa-h NPs. In contrast to PVA/Dpa-s films, PVA/Dpa-h films exhibit stronger UV-shielding capabilities and can almost block the complete UV region (200-400 nm). The excellent UV-shielding performance of the PVA/Dpa-h films mainly arises from multiple absorption because of the hollow structure and large specific area of Dpa-h NPs. Moreover, the wall thickness of Dpa-h NPs can be simply controlled from 28 to 8 nm, depending on the ratio between PS and dopamine. The resulting films with Dpa-h NPs (wall thickness = ∼8 nm) maintained relatively high transparency to visible light because of the thinner wall thickness. The results indicate that the prepared Dpa-h NPs can be used as a novel UV absorber for next-generation transparent UV-shielding materials.

Anomalous absorption of isolated silver nanoparticulate films in visible region of electromagnetic field.

PubMed

Kim, Sang Woo; Hui, Bang Jae; Bae, Dong-Sik

2008-02-01

Anomalous absorption of isolated silver nanoparticulate films with different morphological patterns prepared by the wet colloidal route and followed by thermal treatment were investigated. A polymer embedded silver nanoparticulate film thermally treated at 200 degrees C showed maximum absorbance at approximately 412 nm. The peak position of the surface plasmon band was slightly different but still consistent with theoretical prediction derived by the Mie theory. An isolated nanopariculate film thermally treated at 300 degrees C showed anomalous absorption. Its maximum absorption band was shifted to green regime of 506.9 nm and the bandwidth at half-maximum absorbance of the surface plasmon band was greatly broadened. The plasmon band and its bandwidth were much deviated compared to the theoretical prediction calculated for the silver nanoparticles in the surrounding medium of air and poly(vinyl pyrrolidone) or soda-lime-silica glass. Even though there was no significant growth of silver nanoparticles during thermal treatment at 300 degrees C, the anomalous absorption was observed. The anomalous absorption was not attributed to effects of particle shape and size but to effects of pores induced by development of a great number of pores in the nanoparticulate film. The anomalous absorption greatly decreased with increase in heating temperature from 400 degrees C to 500 degrees C. The extraordinary plasmon damping of the isolated film decreased and the plasmon absorption band was re-shifted to violet regime of 416 nm because of large decrease in size of particles with dramatic change of pore morphology from circular pores with rim to small continuous pores induced by spontaneous formation of new silver nanoparticles.

Optical stress generator and detector

DOEpatents

Maris, Humphrey J.; Stoner, Robert J

2001-01-01

Disclosed is a system for the characterization of thin films and interfaces between thin films through measurements of their mechanical and thermal properties. In the system light is absorbed in a thin film or in a structure made up of several thin films, and the change in optical transmission or reflection is measured and analyzed. The change in reflection or transmission is used to give information about the ultrasonic waves that are produced in the structure. The information that is obtained from the use of the measurement methods and apparatus of this invention can include: (a) a determination of the thickness of thin films with a speed and accuracy that is improved compared to earlier methods; (b) a determination of the thermal, elastic, and optical properties of thin films; (c) a determination of the stress in thin films; and (d) a characterization of the properties of interfaces, including the presence of roughness and defects.

Optical stress generator and detector

DOEpatents

Maris, Humphrey J.; Stoner, Robert J.

1998-01-01

Disclosed is a system for the characterization of thin films and interfaces between thin films through measurements of their mechanical and thermal properties. In the system light is absorbed in a thin film or in a structure made up of several thin films, and the change in optical transmission or reflection is measured and analyzed. The change in reflection or transmission is used to give information about the ultrasonic waves that are produced in the structure. The information that is obtained from the use of the measurement methods and apparatus of this invention can include: (a) a determination of the thickness of thin films with a speed and accuracy that is improved compared to earlier methods; (b) a determination of the thermal, elastic, and optical properties of thin films; (c) a determination of the stress in thin films; and (d) a characterization of the properties of interfaces, including the presence of roughness and defects.

Optical stress generator and detector

DOEpatents

Maris, H.J.; Stoner, R.J.

1998-05-05

Disclosed is a system for the characterization of thin films and interfaces between thin films through measurements of their mechanical and thermal properties. In the system light is absorbed in a thin film or in a structure made up of several thin films, and the change in optical transmission or reflection is measured and analyzed. The change in reflection or transmission is used to give information about the ultrasonic waves that are produced in the structure. The information that is obtained from the use of the measurement methods and apparatus of this invention can include: (a) a determination of the thickness of thin films with a speed and accuracy that is improved compared to earlier methods; (b) a determination of the thermal, elastic, and optical properties of thin films; (c) a determination of the stress in thin films; and (d) a characterization of the properties of interfaces, including the presence of roughness and defects. 32 figs.

Optical stress generator and detector

DOEpatents

Maris, Humphrey J.; Stoner, Robert J

2002-01-01

Disclosed is a system for the characterization of thin films and interfaces between thin films through measurements of their mechanical and thermal properties. In the system light is absorbed in a thin film or in a structure made up of several thin films, and the change in optical transmission or reflection is measured and analyzed. The change in reflection or transmission is used to give information about the ultrasonic waves that are produced in the structure. The information that is obtained from the use of the measurement methods and apparatus of this invention can include: (a) a determination of the thickness of thin films with a speed and accuracy that is improved compared to earlier methods; (b) a determination of the thermal, elastic, and optical properties of thin films; (c) a determination of the stress in thin films; and (d) a characterization of the properties of interfaces, including the presence of roughness and defects.

Optical stress generator and detector

DOEpatents

Maris, Humphrey J.; Stoner, Robert J

1999-01-01

Disclosed is a system for the characterization of thin films and interfaces between thin films through measurements of their mechanical and thermal properties. In the system light is absorbed in a thin film or in a structure made up of several thin films, and the change in optical transmission or reflection is measured and analyzed. The change in reflection or transmission is used to give information about the ultrasonic waves that are produced in the structure. The information that is obtained from the use of the measurement methods and apparatus of this invention can include: (a) a determination of the thickness of thin films with a speed and accuracy that is improved compared to earlier methods; (b) a determination of the thermal, elastic, and optical properties of thin films; (c) a determination of the stress in thin films; and (d) a characterization of the properties of interfaces, including the presence of roughness and defects.

Synthesis and characterization of ZnO thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anilkumar, T. S., E-mail: anil24march@gmail.com; Girija, M. L., E-mail: girija.ml.grt1@gmail.com; Venkatesh, J., E-mail: phph9502@yahoo.com

2016-05-06

Zinc oxide (ZnO) Thin films were deposited on glass substrate using Spin coating method. Zinc acetate dehydrate, Carbinol and Mono-ethanolamine were used as the precursor, solvent and stabilizer respectively to prepare ZnO Thin-films. The molar ratio of Monoethanolamine to Zinc acetate was maintained as approximately 1. The thickness of the films was determined by Interference technique. The optical properties of the films were studied by UV Vis-Spectrophotometer. From transmittance and absorbance curve, the energy band gap of ZnO is found out. Electrical Conductivity measurements of ZnO are carried out by two probe method and Activation energy for the electrical conductivitymore » of ZnO are found out. The crystal structure and orientation of the films were analyzed by XRD. The XRD patterns show that the ZnO films are polycrystalline with wurtzite hexagonal structure.« less

Influence of external magnetic field on the microwave absorption properties of carbonyl iron and polychloroprene composites film

NASA Astrophysics Data System (ADS)

Wang, Haiyan; Li, Mingjie; Li, Xueai

2016-12-01

The carbonyl iron particles were dispersed in a polychloroprene rubber (CR) matrix under a magnetic field for a practical application as microwave absorption composites film. In comparison with the carbonyl iron particles (CIP)/CR composites film prepared by general route, such films made with external magnetic field exhibit excellent microwave absorption properties, strongly depending on the increment of anisotropy and rearrangement of magnetic particles. The film made under external magnetic field with a thickness of only 0.54 mm shows least reflection loss of -15.98 dB and the reflection loss value less than -10.0 dB over the frequency range of 11.4˜14.8 GHz. The results indicated the composite film made under external magnetic field have excellent microwave absorption properties, which suggest that the composites thin film could be used as a thinner and lighter microwave absorber.

Nanostructural characterization of amorphous diamondlike carbon films

DOE Office of Scientific and Technical Information (OSTI.GOV)

SIEGAL,MICHAEL P.; TALLANT,DAVID R.; MARTINEZ-MIRANDA,L.J.

2000-01-27

Nanostructural characterization of amorphous diamondlike carbon (a-C) films grown on silicon using pulsed-laser deposition (PLD) is correlated to both growth energetic and film thickness. Raman spectroscopy and x-ray reflectivity probe both the topological nature of 3- and 4-fold coordinated carbon atom bonding and the topographical clustering of their distributions within a given film. In general, increasing the energetic of PLD growth results in films becoming more ``diamondlike'', i.e. increasing mass density and decreasing optical absorbance. However, these same properties decrease appreciably with thickness. The topology of carbon atom bonding is different for material near the substrate interface compared to materialmore » within the bulk portion of an a-C film. A simple model balancing the energy of residual stress and the free energies of resulting carbon topologies is proposed to provide an explanation of the evolution of topographical bonding clusters in a growing a-C film.« less

Effects of ambient conditions on the adhesion of cubic boron nitride films on silicon substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardinale, G.F.; Howitt, D.G.; Mirkarimi, P.B.

1994-08-01

Effect of environmental conditions on cubic boron nitride (cBN) film adhesion to silicon substrates was studied. cBN films were deposited onto (100)-oriented silicon substrates by ion-assisted pulsed laser deposition. Irradiating ions were mixtures of nitrogen with argon, krypton, and xenon. Under room-ambient conditions, the films delaminated in the following time order: N/Xe, N/Kr, and N/Ar. cBN films deposited using N/Xe ion-assisted deposition were exposed to four environmental conditions for several weeks: a 1-mTorr vacuum, high humidity, dry oxygen, and dry nitrogen. Films exposed to the humid environment delaminated whereas those stored under vacuum or in dry gases did not. Filmsmore » stored in dry nitrogen were removed after nearly two weeks and placed in the high-humidity chamber; these films subsequently delaminated within 14 hours.« less

Water surface assisted synthesis of large-scale carbon nanotube film for high-performance and stretchable supercapacitors.

PubMed

Yu, Minghao; Zhang, Yangfan; Zeng, Yinxiang; Balogun, Muhammad-Sadeeq; Mai, Kancheng; Zhang, Zishou; Lu, Xihong; Tong, Yexiang

2014-07-16

A kind of multiwalled carbon-nanotube (MWCNT)/polydimethylsiloxane (PDMS) film with excellent conductivity and mechanical properties is developed using a facile and large-scale water surface assisted synthesis method. The film can act as a conductive support for electrochemically active PANI nano fibers. A device based on these PANI/MWCNT/PDMS electrodes shows good and stable capacitive behavior, even under static and dynamic stretching conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural and optical properties of nanostructured CdSe thin films prepared by electrochemical deposition

NASA Astrophysics Data System (ADS)

Bai, Rekha; Chaudhary, Sujeet; Pandya, Dinesh K.

2018-05-01

Cadmium selenide (CdSe) nanostructured thin films have been grown on fluorine doped tin oxide (FTO) coated glass substrates by potentiostatic electrochemical deposition (ECD) technique for use in solar energy conversion devices. The effect of bath temperature on the structural, morphological and optical properties of prepared CdSe films has been explored. X-ray diffraction (XRD) and Raman spectroscopy clearly show that the CdSe films are polycrystalline and exhibit phase transformation from wurtzite to zincblende structure with increase in bath temperature. Optical spectra reveal that the nanostructured CdSe films have high absorbance in visible region and the films show a red shift in direct optical energy band gap from 1.90 to 1.65 eV with increase in bath temperature due to change in phase and bandgap tuning related to quantum confinement effect.

Ultrasonic-assisted preparation of graphene oxide carboxylic acid polyvinyl alcohol polymer film and studies of thermal stability and surface resistivity.

PubMed

Li, Yongshen; Li, Jihui; Li, Yuehai; Li, Yali; Song, Yunan; Niu, Shuai; Li, Ning

2018-01-01

In this paper, flake graphite, nitric acid and acetic anhydride are used to prepare graphene oxide carboxylic acid (GO-COOH) via an ultrasonic-assisted method, and GO-COOH and polyvinyl alcohol polymer (PVA) are used to synthesize graphene oxide carboxylic acid polyvinyl alcohol polymer (GO-COOPVA) via the ultrasonic-assisted method, and GO-COOPVA is used to manufacture graphene oxide carboxylic acid polyvinyl alcohol polymer film (GO-COOPVA film) via a solidification method, and the structure and morphology of GO-COOH, GO-COOPVA and GO-COOPVA film are characterized, and the thermal stability and surface resistivity are measured in the case of the different amount of GO-COOH. Based on the characterization and measurement, it has been successively confirmed and attested that carboxyl groups implant on 2D lattice of GO to form GO-COOH, and GO-COOH and PVA have the esterification reaction to produce GO-COOPVA, and GO-COOPVA consists of 2D lattice of GO-COOH and the chain of PVA connected in the form of carboxylic ester, and GO-COOPVA film is composed of GO-COOPVA, and the thermal stability of GO-COOPVA film obviously improves in comparison with PVA film, and the surface resistivity of GO-COOPVA film clearly decreases. Copyright © 2017 Elsevier B.V. All rights reserved.

Grain Growth in Cu2ZnSnS4 Thin Films Using Sn Vapor Transport for Photovoltaic Applications

NASA Astrophysics Data System (ADS)

Toyama, Toshihiko; Konishi, Takafumi; Seo, Yuichi; Tsuji, Ryotaro; Terai, Kengo; Nakashima, Yuto; Okamoto, Hiroaki; Tsutsumi, Yasuo

2013-07-01

Cu2ZnSnS4 thin films containing grains grown using Sn vapor transport (TVT) were investigated. Structural characterization revealed that the grain sizes were equal to or larger than the film thickness (1-4 µm) and significantly larger than those in the case of growth without TVT (60 nm). Furthermore, no phase separation was detected. Photothermal diffraction spectroscopy revealed that the optical absorption coefficient was very low in the subgap region, 7×101 cm-1, suggesting the suppression of defect formation. Finally, a TVT-processed thin film was used as an absorber in a solar cell, and a conversion efficiency of 6.9% was achieved.

Understanding sunscreen SPF performance using cross-polarized UVA reflectance photography.

PubMed

Crowther, J M

2018-04-01

Objective methods for understanding sunscreen behaviour in vitro before they are applied to the skin have failed to keep pace with the ever-increasing demands for higher SPF scores where the products are absorbing more and more similar levels of UV. A novel method for visualizing the spreading and location of SPF ingredients based on cross-polarized UVA reflectance photography is described here which gives new insights into the formation of final film morphology and how it correlates with in vivo SPF efficacy for a set of test products. High-resolution UVA-based images of sunscreen films spread onto PMMA plates were captured using a modified commercial SLR camera in a custom imaging system. Visual grading and image analysis were used to describe the overall UVA absorbance and streakiness of the resultant films, and the data compared with both in vivo and calculated in vitro SPF scores for the products. Differences were observed between the products in terms of how they spread during application. A strong correlation was observed between the evenness of the resultant film as determined from the photographs and final in vivo SPF scores. Cross-polarized UVA reflectance photography has been demonstrated to be a valuable new method for assessing sunscreen distribution after spreading and to differentiate product based on film morphology, as well as strongly correlating with final in vivo behaviour. © 2017 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Effect of in situ electric-field-assisted growth on antiphase boundaries in epitaxial Fe3O4 thin films on MgO

NASA Astrophysics Data System (ADS)

Kumar, Ankit; Wetterskog, Erik; Lewin, Erik; Tai, Cheuk-Wai; Akansel, Serkan; Husain, Sajid; Edvinsson, Tomas; Brucas, Rimantas; Chaudhary, Sujeet; Svedlindh, Peter

2018-05-01

Antiphase boundaries (APBs) normally form as a consequence of the initial growth conditions in all spinel ferrite thin films. These boundaries result from the intrinsic nucleation and growth mechanism, and are observed as regions where the periodicity of the crystalline lattice is disrupted. The presence of APBs in epitaxial films of the inverse spinel Fe3O4 alters their electronic and magnetic properties due to strong antiferromagnetic (AF) interactions across these boundaries. We explore the effect of using in-plane in situ electric-field-assisted growth on the formation of APBs in heteroepitaxial Fe3O4 (100)/MgO(100) thin films. The electric-field-assisted growth is found to reduce the AF interactions across APBs and, as a consequence, APB-free thin-film-like properties are obtained, which have been probed by electronic, magnetic, and structural characterization. The electric field plays a critical role in controlling the density of APBs during the nucleation process by providing an electrostatic force acting on adatoms and therefore changing their kinetics. This innovative technique can be employed to grow epitaxial spinel thin films with controlled AF interactions across APBs.

Shock absorber servicing tool

NASA Technical Reports Server (NTRS)

Koepler, Jack L. (Inventor); Hill, Robert L. (Inventor)

1981-01-01

A tool to assist in the servicing of a shock absorber wherein the shock absorber is constructed of a pair of aligned gas and liquid filled chambers. Each of the chambers is separated by a movable separator member. Maximum efficiency of the shock absorber is achieved in the locating of a precise volume of gas within the gas chamber and a precise volume of liquid within the liquid chamber. The servicing tool of this invention employs a rod which is to connect with the separator and by observation of the position of the rod with respect to the gauge body, the location of the separator is ascertained even though it is not directly observable.

Zinc oxyfluoride transparent conductor

DOEpatents

Gordon, Roy G.

1991-02-05

Transparent, electrically conductive and infrared-reflective films of zinc oxyfluoride are produced by chemical vapor deposition from vapor mixtures of zinc, oxygen and fluorine-containing compounds. The substitution of fluorine for some of the oxygen in zinc oxide results in dramatic increases in the electrical conductivity. For example, diethyl zinc, ethyl alcohol and hexafluoropropene vapors are reacted over a glass surface at 400.degree. C. to form a visibly transparent, electrically conductive, infrared reflective and ultraviolet absorptive film of zinc oxyfluoride. Such films are useful in liquid crystal display devices, solar cells, electrochromic absorbers and reflectors, energy-conserving heat mirrors, and antistatic coatings.

Electrodeposition of near stoichiometric CuInSe2 thin films for photovoltaic applications

NASA Astrophysics Data System (ADS)

Chandran, Ramkumar; Mallik, Archana

2018-03-01

This work investigates on the single step electrodeposition of quality CuInSe2 (CIS) thin film absorber layer for photovoltaics applications. The electrodeposition was carried using an aqueous acidic solution with a pH of 2.25. The deposition was carried using a three electrode system in potentiostatic conditions for 50 minutes. The as-deposited and nitrogen (N2) annealed films were characterized using XRD, FE-SEM and Raman spectroscopy. It has been observed that the SDS has the tendency to suppress the copper selenide (CuxSe) secondary phase which is detrimental to the device performance.

Stable high-power saturable absorber based on polymer-black-phosphorus films

NASA Astrophysics Data System (ADS)

Mao, Dong; Li, Mingkun; Cui, Xiaoqi; Zhang, Wending; Lu, Hua; Song, Kun; Zhao, Jianlin

2018-01-01

Black phosphorus (BP), a rising two-dimensional material with a layer-number-dependent direct bandgap of 0.3-1.5 eV, is very interesting for optoelectronics applications from near- to mid-infrared wavebands. In the atmosphere, few-layer BP tends to be oxidized or degenerated during interacting with lasers. Here, we fabricate few-layer BP nanosheets based on a liquid exfoliation method using N-methylpyrrolidone as the dispersion liquid. By incorporating BP nanosheets with polymers (polyvinyl alcohol or high-melting-point polyimide), two flexible filmy BP saturable absorbers are fabricated to realize passive mode locking in erbium-doped fiber lasers. The polymer-BP saturable absorber, especially the polyimide-BP saturable absorber, can prevent the oxidation or water-induced etching under high-power laser illuminations, providing a promising candidate for Q-switchers, mode lockers, and light modulators.

CuInSe₂ thin-film solar cells with 7.72 % efficiency prepared via direct coating of a metal salts/alcohol-based precursor solution.

PubMed

Ahn, Sejin; Son, Tae Hwa; Cho, Ara; Gwak, Jihye; Yun, Jae Ho; Shin, Keeshik; Ahn, Seoung Kyu; Park, Sang Hyun; Yoon, Kyunghoon

2012-09-01

A simple direct solution coating process for forming CuInSe₂ (CIS) thin films was described, employing a low-cost and environmentally friendly precursor solution. The precursor solution was prepared by mixing metal acetates, ethanol, and ethanolamine. The facile formation of a precursor solution without the need to prefabricate nanoparticles enables a rapid and easy processing, and the high stability of the solution in air further ensures the precursor preparation and the film deposition in ambient conditions without a glove box. The thin film solar cell fabricated with the absorber film prepared by this route showed an initial conversion efficiency of as high as 7.72 %. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Foam flow and liquid films motion: role of the surfactants properties

NASA Astrophysics Data System (ADS)

Cantat, Isabelle

2011-11-01

Liquid foams absorb energy in a much more efficient way than each of its constituents, taken separately. However, the local process at the origin of the energy dissipation is not entirely elucidated yet, and several models may apply, thus making worth local studies on simpler systems. We investigate the motion through a wet tube of transverse soap films, or lamellae, combining local thickness and velocity measurements in the wetting film. For foaming solution with a high dilatational surface modulus, we reveal a zone of several centimeters in length, the dynamic wetting film, which is significantly influenced by a moving lamella. The dependence of this influence length on lamella velocity and wetting film thickness provides an accurate discrimination among several possible surfactants models. In collaboration with B. Dollet.

High precision slotted cavity measurement of a novel ceramic state polymer electrolyte

NASA Astrophysics Data System (ADS)

Quan, Wei; NurulAfsar, Mohammed

2018-01-01

Thin film materials are already used in a variety of microwave and higher frequency applications such as electrically tunable microwave devices, integrated circuits like MMICs, radomes, and radar absorbing coating. The determination of the dielectric properties of these films is thus of significant importance. The measurement of complex dielectric permittivity of thin films is very difficult at microwave, millimeter, and THz frequencies because both the amplitude change and phase shift are not large enough to evaluate the real part of the dielectric permittivity. A specially designed transverse slotted cavity for X-band microwave measurement has been designed and constructed to employ with a vector network analyzer to evaluate the real part of dielectric permittivity of thin films accurately and conveniently. Commercially available polymer thin films are measured to validate the methods.

Photopatternable sorbent and functionalized films

DOEpatents

Grate, Jay W [West Richland, WA; Nelson, David A [Richland, WA

2006-01-31

A composition containing a polymer, a crosslinker and a photo-activatable catalyst is placed on a substrate. The composition is exposed to a predetermined pattern of light, leaving an unexposed region. The light causes the polymer to become crosslinked by hydrosilylation. A solvent is used to remove the unexposed composition from the substrate, leaving the exposed pattern to become a sorbent polymer film that will absorb a predetermined chemical species when exposed to such chemical species.

Investigation of the Emissivity and Suitability of a Carbon Thin Film for Terahertz Absorbers

DTIC Science & Technology

2016-06-01

Carbonization In order to verify whether the carbon soot coated THz sensor produces sufficient spectral emissivity for IR-based readout, dummy test...ABSTRACT (maximum 200 words) The main goal of this work is to optimize the emissivity of terahertz (THz) thermal sensors by deposition of a carbon thin...film. Previously, these thermal sensors were designed to detect THz radiation utilizing metamaterials in a complicated optical probing scheme. We

[Assisted suicide in the movies - what is (not) shown?

PubMed

Schmidt, Kurt W

2017-01-01

Whereas changes to the existing legal situation regarding assisted suicide have been a topic of controversial debate in Germany for the last few years, this issue has long been of interest for international film-makers. Since the mid-1980s, the theme of assisted suicide has repeatedly been taken up by cinema, predominantly as central to a relationship drama. A sick person asks somebody close to them for help. Often this somebody is a physician or a nurse, ultimately an obvious way of solving the practical problem of how the assistant is to gain access to a lethal substance. At the same time, this constellation enables a physician or nurse to be forced into a dramatic conflict between professional ethics and a personal obligation towards a loved one.Alongside more classic clinical pictures such as terminal cancer, recent films about assisted suicide have featured neurodegenerative diseases and physical disabilities. Another new development is that elderly patients are no longer alone in requesting assistance; films also and increasingly portray young adults. Besides a fear of unbearable pain, more recent films have also increasingly addressed the worry that permanent nursing might be required, as well as the subjectively experienced loss of dignity. The possibilities offered by palliative care hardly play a role in feature films. However, we should not forget, that movies are fictional and orchestrated, or, in other words, they are neither educational nor documental. They neither need nor want to portray reality, although they do wish to draw upon real experiences. They exploit highly emotional and ethically controversial themes to create tensions and stir up emotions in the audience, but ultimately they seek to entertain. Movies about death and dying are always "die-tainment".

Generation of an ultrafast femtosecond soliton fiber laser by carbon nanotube as saturable absorber

NASA Astrophysics Data System (ADS)

Salim, M. A. M.; Ahmad, H.; Harun, S. W.; Bidin, N.; Krishnan, G.

2018-05-01

This paper reports the demonstration of ultrafast fiber laser in a simple erbium-doped fiber (EDF) laser that employed a carbon nanotube (CNT) thin film saturable absorber (SA) to generate a stable soliton pulse. The repetition rate of 10.8 MHz pulse consistently achieved has narrowest pulse width of 640 fs and 1555.78 nm central wavelength for an hour operation in room temperature. This proposed setup has the capability for reliable and stable system features.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Laura; Harvey, Stephen P.; Teeter, Glenn

We demonstrate the potential of X-ray photoelectron spectroscopy (XPS) to characterize new carrier-selective contacts (CSC) for solar cell application. We show that XPS not only provides information about the surface chemical properties of the CSC material, but that operando XPS, i.e. under light bias condition, can also directly measure the photovoltage that develops at the CSC/absorber interface, revealing device relevant information without the need of assembling a full solar cell. We present the application of the technique to molybdenum oxide hole-selective contact films on a crystalline silicon absorber.

Organic Photovoltaic Devices Based on Oriented n-Type Molecular Films Deposited on Oriented Polythiophene Films.

PubMed

Mizokuro, Toshiko; Tanigaki, Nobutaka; Miyadera, Tetsuhiko; Shibata, Yousei; Koganezawa, Tomoyuki

2018-04-01

The molecular orientation of π-conjugated molecules has been reported to significantly affect the performance of organic photovoltaic devices (OPVs) based on molecular films. Hence, the control of molecular orientation is a key issue toward the improvement of OPV performance. In this research, oriented thin films of an n-type molecule, 3,4,9,10-Perylenetetracarboxylic Bisbenzimida-zole (PTCBI), were formed by deposition on in-plane oriented polythiophene (PT) films. Orientation of the PTCBI films was evaluated by polarized UV-vis spectroscopy and 2D-Grazing incidence X-ray diffraction. Results indicated that PTCBI molecules on PT film exhibit nearly edge-on and in-plane orientation (with molecular long axis along the substrate), whereas PTCBI molecules without PT film exhibit neither. OPVs composed of PTCBI molecular film with and without PT were fabricated and evaluated for correlation of orientation with performance. The OPVs composed of PTCBI film with PT showed higher power conversion efficiency (PCE) than that of film without PT. The experiment indicated that in-plane orientation of PTCBI molecules absorbs incident light more efficiently, leading to increase in PCE.

Optimization of high quality Cu2ZnSnS4 thin film by low cost and environment friendly sol-gel technique for thin film solar cells applications

NASA Astrophysics Data System (ADS)

Chaudhari, J. J.; Joshi, U. S.

2018-05-01

In this study kesterite Cu2ZnSnS4 (CZTS) thin films suitable for absorber layer in thin film solar cells (TFSCs) were successfully fabricated on glass substrate by sol-gel method. The effects of complexing agent on formation of CZTS thin films have been investigated. X-ray diffraction (XRD) analysis confirms formation of polycrystalline CZTS thin films with single phase kesterite structure. XRD and Raman spectroscopy analysis of CZTS thin films with optimized concentration of complexing agent confirmed formation of kesterite phase in CZTS thin films. The direct optical band gap energy of CZTS thin films is found to decrease from 1.82 to 1.50 eV with increase of concentration of complexing agent triethanolamine. Morphological analysis of CZTS thin films shows smooth, uniform and densely packed CZTS grains and increase in the grain size with increase of concentration of complexing agent. Hall measurements revealed that concentration of charge carrier increases and resistivity decreases in CZTS thin films as amount of complexing agent increases.

Realizing high-performance metamaterial absorber based on the localized surface plasmon resonance in the terahertz regime

NASA Astrophysics Data System (ADS)

Yunfeng, Lin; Xiaoqi, Hu; Lin, Hu

2018-04-01

A composite structure design metamaterial absorber is designed and simulated. The proposed composite structure consists of a double-hole sub-structure and a double-metallic particle sub-structure. The damping constant of bulk gold layer is optimized to eliminate the adverse effects of the grain boundary and the surface scattering of thin films on the absorption property. Two absorption peaks (A1 = 58%, A2 = 23%) are achieved based on the localized surface plasmon (LSP) modes resonance. Moreover, the plasmonic hybridization phenomenon between LSP modes is found, which leads to the absorption enhancement between two absorption peaks. The proposed metamaterial absorber holds the property of wide-angle incidence.

A Cooperative Film Effort in Colorado

ERIC Educational Resources Information Center

Spetnagel, H. T.; And Others

1972-01-01

The mass communications department of the University of Denver assisted in producing a film on community colleges in Colorado which improved the film students' cinema skills while providing greater exposure for the community college system. (NF)

Characterization of Nanostructured Polymer Films

DTIC Science & Technology

2014-12-23

discovered that polymer films with exceptional thermal and kinetic stability could be formed by Matrix Assisted Pulsed Laser Evaporation ( MAPLE ) onto...thermal properties of amorphous polymer nanoglobules fabricated via Matrix-Assisted Pulsed Laser Deposition ( MAPLE ). We discovered that stability in... MAPLE , Glass Transition Temperature 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON

CH3NH3I treatment temperature of 70 °C in low-pressure vapor-assisted deposition for mesoscopic perovskite solar cells

NASA Astrophysics Data System (ADS)

Jin, Wenbin; Zou, Xiaoping; Bai, Xiao; Yang, Ying; Chen, Dan

2018-01-01

Herein, we report a modified vapor-assisted deposition method to fabricate CH3NH3PbI3 film at 70 °C in a vacuum drying oven. The modified method has excellent operability and expandability in preparing perovskite solar cells. The CH3NH3I treatment temperature is 130 °C or 150 °C in conventional method, but we reduced the temperature to 70 °C in the modified vapor-assisted method. Meanwhile, the quality of CH3NH3PbI3 films prepared via the modified method is superior to that of CH3NH3PbI3 films of solution-processed method.

Evaluation of mechanism of cold atmospheric pressure plasma assisted polymerization of acrylic acid on low density polyethylene (LDPE) film surfaces: Influence of various gaseous plasma pretreatment

NASA Astrophysics Data System (ADS)

Ramkumar, M. C.; Pandiyaraj, K. Navaneetha; Arun Kumar, A.; Padmanabhan, P. V. A.; Uday Kumar, S.; Gopinath, P.; Bendavid, A.; Cools, P.; De Geyter, N.; Morent, R.; Deshmukh, R. R.

2018-05-01

Owing to its exceptional physiochemical properties, low density poly ethylene (LDPE) has wide range of tissue engineering applications. Conversely, its inadequate surface properties make LDPE an ineffectual candidate for cell compatible applications. Consequently, plasma-assisted polymerization with a selected precursor is a good choice for enhancing its biocompatibility. The present investigation studies the efficiency of plasma polymerization of acrylic acid (AAC) on various gaseous plasma pretreated LDPE films by cold atmospheric pressure plasma, to enhance its cytocompatibility. The change in chemical composition and surface topography of various gaseous plasma pretreated and acrylic deposited LDPE films has been assessed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The changes in hydrophilic nature of surface modified LDPE films were studied by contact angle (CA) analysis. Cytocompatibility of the AAC/LDPE films was also studied in vitro, using RIN-5F cells. The results acquired by the XPS and AFM analysis clearly proved that cold atmospheric pressure (CAP) plasma assisted polymerization of AAC enhances various surface properties including carboxylic acid functional group density and increased surface roughness on various gaseous plasma treated AAC/LDPE film surfaces. Moreover, contact angle analysis clearly showed that the plasma polymerized samples were hydrophilic in nature. In vitro cytocompatibility analysis undoubtedly validates that the AAC polymerized various plasma pretreated LDPE films surfaces stimulate cell distribution and proliferation compared to pristine LDPE films. Similarly, cytotoxicity analysis indicates that the AAC deposited various gaseous plasma pretreated LDPE film can be considered as non-toxic as well as stimulating cell viability significantly. The cytocompatible properties of AAC polymerized Ar + O2 plasma pretreated LDPE films were found to be more pronounced compared to the other plasma pretreated AAC/LDPE films.

Growth of KOH etched AZO nanorods and investigation of its back scattering effect in thin film a-Si solar cell

NASA Astrophysics Data System (ADS)

Sharma, Jayasree Roy; Mitra, Suchismita; Ghosh, Hemanta; Das, Gourab; Bose, Sukanta; Mandal, Sourav; Mukhopadhyay, Sumita; Saha, Hiranmay; Barua, A. K.

2018-02-01

In order to increase the stabilized efficiencies of thin film silicon (TFS) solar cells it is necessary to use better light management techniques. Texturization by etching of sputtered aluminum doped zinc oxide (Al:ZnO or AZO) films has opened up a variety of promises to optimize light trapping schemes. RF sputtered AZO film has been etched by potassium hydroxide (KOH). A systematic study of etching conditions such as etchant concentration, etching time, temperature management etc. have been performed in search of improved electrical and optical performances of the films. The change in etching conditions has exhibited a noticeable effect on the structure of AZO films for which the light trapping effect differs. After optimizing the etching conditions, nanorods have been found on the substrate. Hence, nanorods have been developed only by chemical etching, rather than the conventional development method (hydrothermal method, sol-gel method, electrolysis method etc.). The optimized etched substrate has 82% transmittance, moderate haze in the visible range and sheet resistance ∼13 (Ω/□). The developed nanorods (optimized etched substrate) provide better light trapping within the cell as the optical path length has been increased by using the nanorods. This provides an effect on carrier collection as well as the efficiency in a-Si solar cells. Finite difference time domain (FDTD) simulations have been performed to observe the light trapping by AZO nanorods formed on sputtered AZO films. For a p-i-n solar cell developed on AZO nanorods coated with sputtered AZO films, it has been found through simulations that, the incident light is back scattered into the absorbing layer, leading to an increase in photogenerated current and hence higher efficiency. It has been found that, the light that passes through the nanorods is not getting absorbed and maximum amount of light is back scattered towards the solar cell.

Synthesis and optical characterization of ternary chalcogenide Cu3BiS3 thin film by spin coating

NASA Astrophysics Data System (ADS)

Rawal, Neha; Hadi, Mohammed Kamal; Modi, B. P.

2017-05-01

In this work, ternary Chalcogenide Cu3BiS3(CBS) thin films have been prepared and modified by using spin coating technique. Lucratively, spin coating technique is easy going and simple though it hasn't given an enclosure and extensive focus of researches for Cu3BiS3 thin films formation. The surface smoothness and the homogeneity of the obtained thin films have been optimized throughout varying the annealing temperature, concentration and rotation speed. It had been found that as prepared films the value of the energy band gap is 1.4 eV, the absorption coefficient 105 cm-1. Each values of the EBG (Energy Band Gap) and AC (Absorption coefficient) was found in quite agreement with the published work of CBS thin film formation by other methods as CBD, dip coating etc. It signifies that Cu3BiS3 films can be used as an absorber layer for thin film solar cell.

Electroactive Film of Myoglobin Incorporated in a 3D-porous Calcium Alginate Film with Polyvinyl Alcohol, Glycerin and Gelatin.

PubMed

Zheng, Xueqin; Sun, Hong; Hou, Shifeng

2015-01-01

In this work, an electroactive porous Mb-CA's composite film was fabricated by incorporating myoglobin (Mb) in a three-dimension (3D) porous calcium alginate (CA) film with polyvinyl alcohol, glycerol, and gelatin. The porous Mb-CA's film modified electrodes exhibited a pair of well-defined, quasi-reversible cyclic voltammetric (CV) peaks at about -0.37 V vs. SCE in pH 7.0 buffers, characteristic of Mb heme Fe((III))/Fe((II)) redox couples. The electrochemical parameters, such as formal potentials (E(o')) and apparent heterogeneous electron-transfer rate constants (ks), were estimated by square-wave voltammetry with nonlinear regression analysis. The porous CA's composite film could form hydrogel in aqueous solution. The positions of the Soret absorbance band suggest that Mb in the CA's composite film kept its native states in the medium pH range. Hydrogen peroxide, oxygen, and nitrite were electrochemically catalyzed by the Mb-CA's composite film with significant lowering of the reduction overpotential.

Approximately 800-nm-Thick Pinhole-Free Perovskite Films via Facile Solvent Retarding Process for Efficient Planar Solar Cells.

PubMed

Yuan, Zhongcheng; Yang, Yingguo; Wu, Zhongwei; Bai, Sai; Xu, Weidong; Song, Tao; Gao, Xingyu; Gao, Feng; Sun, Baoquan

2016-12-21

Device performance of organometal halide perovskite solar cells significantly depends on the quality and thickness of perovskite absorber films. However, conventional deposition methods often generate pinholes within ∼300 nm-thick perovskite films, which are detrimental to the large area device manufacture. Here we demonstrated a simple solvent retarding process to deposit uniform pinhole free perovskite films with thicknesses up to ∼800 nm. Solvent evaporation during the retarding process facilitated the components separation in the mixed halide perovskite precursors, and hence the final films exhibited pinhole free morphology and large grain sizes. In addition, the increased precursor concentration after solvent-retarding process led to thick perovskite films. Based on the uniform and thick perovskite films prepared by this convenient process, a champion device efficiency up to 16.8% was achieved. We believe that this simple deposition procedure for high quality perovskite films around micrometer thickness has a great potential in the application of large area perovskite solar cells and other optoelectronic devices.

Epitaxial ternary nitride thin films prepared by a chemical solution method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Hongmei; Feldmann, David M; Wang, Haiyan

2008-01-01

It is indispensable to use thin films for many technological applications. This is the first report of epitaxial growth of ternary nitride AMN2 films. Epitaxial tetragonal SrTiN2 films have been successfully prepared by a chemical solution approach, polymer-assisted deposition. The structural, electrical, and optical properties of the films are also investigated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Willian de Souza Lucas, Francisco; Peng, Haowei; Johnston, Steve

Copper antimony disulfide (CuSbS 2) has several excellent bulk optoelectronic properties for photovoltaic absorber applications. Here, we report on the defect properties in CuSbS 2thin film materials and photovoltaic devices studied using several experimental methods supported by theoretical calculations.

Enhancement of near-infrared detectability from InGaZnO thin film transistor with MoS2 light absorbing layer.

PubMed

Pak, Sang Woo; Chu, Dongil; Song, Da Ye; Lee, Seung Kyo; Kim, Eun Kyu

2017-11-24

We report an enhancement of near-infrared (NIR) detectability from amorphous InGaZnO (α-IGZO) thin film transistor in conjunction with randomly distributed molybdenum disulfide (MoS 2 ) flakes. The electrical characteristics of the α-IGZO grown by radio-frequency magnetron sputtering exhibit high effective mobility exceeding 15 cm 2 V -1 s -1 and current on/off ratio up to 10 7 . By taking advantages of the high quality α-IGZO and MoS 2 light absorbing layer, photodetection spectra are able to extend from ultra-violet to NIR range. The α-IGZO channel detector capped by MoS 2 show a photo-responsivity of approximately 14.9 mA W -1 at 1100 nm wavelength, which is five times higher than of the α-IGZO device without MoS 2 layer.

Enhancement of near-infrared detectability from InGaZnO thin film transistor with MoS2 light absorbing layer

NASA Astrophysics Data System (ADS)

Pak, Sang Woo; Chu, Dongil; Song, Da Ye; Kyo Lee, Seung; Kim, Eun Kyu

2017-11-01

We report an enhancement of near-infrared (NIR) detectability from amorphous InGaZnO (α-IGZO) thin film transistor in conjunction with randomly distributed molybdenum disulfide (MoS2) flakes. The electrical characteristics of the α-IGZO grown by radio-frequency magnetron sputtering exhibit high effective mobility exceeding 15 cm2 V-1 s-1 and current on/off ratio up to 107. By taking advantages of the high quality α-IGZO and MoS2 light absorbing layer, photodetection spectra are able to extend from ultra-violet to NIR range. The α-IGZO channel detector capped by MoS2 show a photo-responsivity of approximately 14.9 mA W-1 at 1100 nm wavelength, which is five times higher than of the α-IGZO device without MoS2 layer.

Transition-metal dichalcogenides heterostructure saturable absorbers for ultrafast photonics.

PubMed

Chen, Hao; Yin, Jinde; Yang, Jingwei; Zhang, Xuejun; Liu, Mengli; Jiang, Zike; Wang, Jinzhang; Sun, Zhipei; Guo, Tuan; Liu, Wenjun; Yan, Peiguang

2017-11-01

In this Letter, high-quality WS 2 film and MoS 2 film were vertically stacked on the tip of a single-mode fiber in turns to form heterostructure (WS 2 -MoS 2 -WS 2 )-based saturable absorbers with all-fiber integrated features. Their nonlinear saturable absorption properties were remarkable, such as a large modulation depth (∼16.99%) and a small saturable intensity (6.23  MW·cm -2 ). Stable pulses at 1.55 μm with duration as short as 296 fs and average power as high as 25 mW were obtained in an erbium-doped fiber laser system. The results demonstrate that the proposed heterostructures own remarkable nonlinear optical properties and offer a platform for adjusting nonlinear optical properties by stacking different transition-metal dichalcogenides or modifying the thickness of each layer, paving the way for engineering functional ultrafast photonics devices with desirable properties.

Triple-wavelength passively Q-switched ytterbium-doped fibre laser using zinc oxide nanoparticles film as a saturable absorber

NASA Astrophysics Data System (ADS)

Mohsin Al-Hayali, Sarah Kadhim; Hadi Al-Janabi, Abdul

2018-07-01

We report on the generation of a triple-wavelength passively Q-switched ytterbium-doped fibre laser using a saturable absorber (SA) based on zinc oxide nanoparticles (ZnO NPs) film. The SA was fabricated by embedding ZnO NPs powder into a polyvinyl alcohol as a host polymer. By properly adjusting the pump power and the polarization state, single-, dual- and triple-wavelength Q-switching are stably generated without additional components (such as optical filter, or fibre grating). For the triple wavelength operation, the fibre laser generates a maximum pulse repetition of 87.9 kHz with the shortest pulse duration of 2.7 μs. To the best of authors' knowledge, it's the first demonstration of triple-wavelength passively Q-switching fibre laser using ZnO NPs as a SA. Our results suggest that ZnO is a promising SA for multi-wavelength laser operation.

Surface-plasmon mediated total absorption of light into silicon.

PubMed

Yoon, Jae Woong; Park, Woo Jae; Lee, Kyu Jin; Song, Seok Ho; Magnusson, Robert

2011-10-10

We report surface-plasmon mediated total absorption of light into a silicon substrate. For an Au grating on Si, we experimentally show that a surface-plasmon polariton (SPP) excited on the air/Au interface leads to total absorption with a rate nearly 10 times larger than the ohmic damping rate of collectively oscillating free electrons in the Au film. Rigorous numerical simulations show that the SPP resonantly enhances forward diffraction of light to multiple orders of lossy waves in the Si substrate with reflection and ohmic absorption in the Au film being negligible. The measured reflection and phase spectra reveal a quantitative relation between the peak absorbance and the associated reflection phase change, implying a resonant interference contribution to this effect. An analytic model of a dissipative quasi-bound resonator provides a general formula for the resonant absorbance-phase relation in excellent agreement with the experimental results.

Investigation of properties of nanobridge Josephson junctions and superconducting tracks fabricated by FIB

NASA Astrophysics Data System (ADS)

Li, B.; Godfrey, T.; Cox, D.; Li, T.; Gallop, J.; Galer, S.; Nisbet, A.; Romans, Ed; Hao, L.

2018-02-01

An important requirement across a range of sensitive detectors is to determine accurately the energy deposited by the impact of a particle in a small volume. The particle may be anything from a visible photon through to an X-ray or massive charged particle. We have been developing nanobridge Josephson junctions based SQUIDs and nanoSQUID devices covering the entire range of particle detection energies from 1eV to MeV. In this paper we discuss some developments in nanobridge Josephson junctions fabrication using focussed ion beam (FIB) and how these developments impact future applications. We focus on tuning of the transition temperature of a superconducting thin-film absorber, with the aim to match the absorber Tc to the working temperature range of the SQUID and also on using a new Xe FIB to improve Josephson junction and superconducting film quality.

Thermal tuning of infrared resonant absorbers based on hybrid gold-VO{sub 2} nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kocer, Hasan; Department of Electrical Engineering, Turkish Military Academy, 06654 Ankara; Butun, Serkan

2015-04-20

Resonant absorbers based on plasmonic materials, metamaterials, and thin films enable spectrally selective absorption filters, where absorption is maximized at the resonance wavelength. By controlling the geometrical parameters of nano/microstructures and materials' refractive indices, resonant absorbers are designed to operate at wide range of wavelengths for applications including absorption filters, thermal emitters, thermophotovoltaic devices, and sensors. However, once resonant absorbers are fabricated, it is rather challenging to control and tune the spectral absorption response. Here, we propose and demonstrate thermally tunable infrared resonant absorbers using hybrid gold-vanadium dioxide (VO{sub 2}) nanostructure arrays. Absorption intensity is tuned from 90% to 20%more » and 96% to 32% using hybrid gold-VO{sub 2} nanowire and nanodisc arrays, respectively, by heating up the absorbers above the phase transition temperature of VO{sub 2} (68 °C). Phase change materials such as VO{sub 2} deliver useful means of altering optical properties as a function of temperature. Absorbers with tunable spectral response can find applications in sensor and detector applications, in which external stimulus such as heat, electrical signal, or light results in a change in the absorption spectrum and intensity.« less

Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn1−xGaxSe2 Growth: Indium-Gallium Selenide Co-Evaporation

PubMed Central

Pradhan, Puja; Aryal, Puruswottam; Attygalle, Dinesh; Ibdah, Abdel-Rahman; Koirala, Prakash; Li, Jian; Bhandari, Khagendra P.; Liyanage, Geethika K.; Ellingson, Randy J.; Heben, Michael J.; Marsillac, Sylvain; Collins, Robert W.; Podraza, Nikolas J.

2018-01-01

Real time spectroscopic ellipsometry (RTSE) has been applied for in-situ monitoring of the first stage of copper indium-gallium diselenide (CIGS) thin film deposition by the three-stage co-evaporation process used for fabrication of high efficiency thin film photovoltaic (PV) devices. The first stage entails the growth of indium-gallium selenide (In1−xGax)2Se3 (IGS) on a substrate of Mo-coated soda lime glass maintained at a temperature of 400 °C. This is a critical stage of CIGS deposition because a large fraction of the final film thickness is deposited, and as a result precise compositional control is desired in order to achieve the optimum performance of the resulting CIGS solar cell. RTSE is sensitive to monolayer level film growth processes and can provide accurate measurements of bulk and surface roughness layer thicknesses. These in turn enable accurate measurements of the bulk layer optical response in the form of the complex dielectric function ε = ε1 − iε2, spectra. Here, RTSE has been used to obtain the (ε1, ε2) spectra at the measurement temperature of 400 °C for IGS thin films of different Ga contents (x) deduced from different ranges of accumulated bulk layer thickness during the deposition process. Applying an analytical expression in common for each of the (ε1, ε2) spectra of these IGS films, oscillator parameters have been obtained in the best fits and these parameters in turn have been fitted with polynomials in x. From the resulting database of polynomial coefficients, the (ε1, ε2) spectra can be generated for any composition of IGS from the single parameter, x. The results have served as an RTSE fingerprint for IGS composition and have provided further structural information beyond simply thicknesses, for example information related to film density and grain size. The deduced IGS structural evolution and the (ε1, ε2) spectra have been interpreted as well in relation to observations from scanning electron microscopy, X-ray diffractometry and energy-dispersive X-ray spectroscopy profiling analyses. Overall the structural, optical and compositional analysis possible by RTSE has assisted in understanding the growth and properties of three stage CIGS absorbers for solar cells and shows future promise for enhancing cell performance through monitoring and control. PMID:29337931

Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn1-xGaxSe₂ Growth: Indium-Gallium Selenide Co-Evaporation.

PubMed

Pradhan, Puja; Aryal, Puruswottam; Attygalle, Dinesh; Ibdah, Abdel-Rahman; Koirala, Prakash; Li, Jian; Bhandari, Khagendra P; Liyanage, Geethika K; Ellingson, Randy J; Heben, Michael J; Marsillac, Sylvain; Collins, Robert W; Podraza, Nikolas J

2018-01-16

Real time spectroscopic ellipsometry (RTSE) has been applied for in-situ monitoring of the first stage of copper indium-gallium diselenide (CIGS) thin film deposition by the three-stage co-evaporation process used for fabrication of high efficiency thin film photovoltaic (PV) devices. The first stage entails the growth of indium-gallium selenide (In 1- x Ga x )₂Se₃ (IGS) on a substrate of Mo-coated soda lime glass maintained at a temperature of 400 °C. This is a critical stage of CIGS deposition because a large fraction of the final film thickness is deposited, and as a result precise compositional control is desired in order to achieve the optimum performance of the resulting CIGS solar cell. RTSE is sensitive to monolayer level film growth processes and can provide accurate measurements of bulk and surface roughness layer thicknesses. These in turn enable accurate measurements of the bulk layer optical response in the form of the complex dielectric function ε = ε₁ - iε₂, spectra. Here, RTSE has been used to obtain the (ε₁, ε₂) spectra at the measurement temperature of 400 °C for IGS thin films of different Ga contents ( x ) deduced from different ranges of accumulated bulk layer thickness during the deposition process. Applying an analytical expression in common for each of the (ε₁, ε₂) spectra of these IGS films, oscillator parameters have been obtained in the best fits and these parameters in turn have been fitted with polynomials in x . From the resulting database of polynomial coefficients, the (ε₁, ε₂) spectra can be generated for any composition of IGS from the single parameter, x . The results have served as an RTSE fingerprint for IGS composition and have provided further structural information beyond simply thicknesses, for example information related to film density and grain size. The deduced IGS structural evolution and the (ε₁, ε₂) spectra have been interpreted as well in relation to observations from scanning electron microscopy, X-ray diffractometry and energy-dispersive X-ray spectroscopy profiling analyses. Overall the structural, optical and compositional analysis possible by RTSE has assisted in understanding the growth and properties of three stage CIGS absorbers for solar cells and shows future promise for enhancing cell performance through monitoring and control.

Electromagnetic Wave Absorbing Properties of Amorphous Carbon Nanotubes

PubMed Central

Zhao, Tingkai; Hou, Cuilin; Zhang, Hongyan; Zhu, Ruoxing; She, Shengfei; Wang, Jungao; Li, Tiehu; Liu, Zhifu; Wei, Bingqing

2014-01-01

Amorphous carbon nanotubes (ACNTs) with diameters in the range of 7–50 nm were used as absorber materials for electromagnetic waves. The electromagnetic wave absorbing composite films were prepared by a dip-coating method using a uniform mixture of rare earth lanthanum nitrate doped ACNTs and polyvinyl chloride (PVC). The microstructures of ACNTs and ACNT/PVC composites were characterized using transmission electron microscope and X-ray diffraction, and their electromagnetic wave absorbing properties were measured using a vector-network analyzer. The experimental results indicated that the electromagnetic wave absorbing properties of ACNTs are superior to multi-walled CNTs, and greatly improved by doping 6 wt% lanthanum nitrate. The reflection loss (R) value of a lanthanum nitrate doped ACNT/PVC composite was −25.02 dB at 14.44 GHz, and the frequency bandwidth corresponding to the reflector loss at −10 dB was up to 5.8 GHz within the frequency range of 2–18 GHz. PMID:25007783

Sapphire substrate-induced effects in VO{sub 2} thin films grown by oxygen plasma-assisted pulsed laser deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skuza, J. R., E-mail: jrskuza@nsu.edu, E-mail: apradhan@nsu.edu; Scott, D. W.; Pradhan, A. K., E-mail: jrskuza@nsu.edu, E-mail: apradhan@nsu.edu

2015-11-21

We investigate the structural and electronic properties of VO{sub 2} thin films on c-plane sapphire substrates with three different surface morphologies to control the strain at the substrate-film interface. Only non-annealed substrates with no discernible surface features (terraces) provided a suitable template for VO{sub 2} film growth with a semiconductor-metal transition (SMT), which was much lower than the bulk transition temperature. In addition to strain, oxygen vacancy concentration also affects the properties of VO{sub 2}, which can be controlled through deposition conditions. Oxygen plasma-assisted pulsed laser deposition allows favorable conditions for VO{sub 2} film growth with SMTs that can bemore » easily tailored for device applications.« less

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

NASA Astrophysics Data System (ADS)

Shaji, S.; Garcia, L. V.; Loredo, S. L.; Krishnan, B.; Aguilar Martinez, J. A.; Das Roy, T. K.; Avellaneda, D. A.

2017-01-01

Antimony sulfide (Sb2S3) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb2S3 thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb2S3 thin films for optoelectronic applications.

A Two-Step Absorber Deposition Approach To Overcome Shunt Losses in Thin-Film Solar Cells: Using Tin Sulfide as a Proof-of-Concept Material System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steinmann, Vera; Chakraborty, Rupak; Rekemeyer, Paul H.

2016-08-31

As novel absorber materials are developed and screened for their photovoltaic (PV) properties, the challenge remains to reproducibly test promising candidates for high-performing PV devices. Many early-stage devices are prone to device shunting due to pinholes in the absorber layer, producing 'false-negative' results. Here, we demonstrate a device engineering solution toward a robust device architecture, using a two-step absorber deposition approach. We use tin sulfide (SnS) as a test absorber material. The SnS bulk is processed at high temperature (400 degrees C) to stimulate grain growth, followed by a much thinner, low-temperature (200 degrees C) absorber deposition. At a lowermore » process temperature, the thin absorber overlayer contains significantly smaller, densely packed grains, which are likely to provide a continuous coating and fill pinholes in the underlying absorber bulk. We compare this two-step approach to the more standard approach of using a semi-insulating buffer layer directly on top of the annealed absorber bulk, and we demonstrate a more than 3.5x superior shunt resistance Rsh with smaller standard error ..sigma..Rsh. Electron-beam-induced current (EBIC) measurements indicate a lower density of pinholes in the SnS absorber bulk when using the two-step absorber deposition approach. We correlate those findings to improvements in the device performance and device performance reproducibility.« less

The investigation of optimal Silicon/Silicon(1-x)Germanium(x) thin-film solar cells with quantitative analysis

NASA Astrophysics Data System (ADS)

Ehsan, Md Amimul

Thin-film solar cells are emerging from the research laboratory to become commercially available devices for low cost electrical power generation applications. Silicon which is a cheap, abundant and non-toxic elemental semiconductor is an attractive candidate for these solar cells. Advanced modeling and simulation of Si thin-film solar cells has been performed to make this technology more cost effective without compromising the performance and efficiency. In this study, we focus on the design and optimization of Si/Si1-xGex heterostructures, and microcrystalline and nanocrystalline Si thin-film solar cells. Layer by layer optimization of these structures was performed by using advanced bandgap engineering followed by numerical analysis for their structural, electrical and optical characterizations. Special care has been introduced for the selection of material layers which can help to improve the light absorption properties of these structures for harvesting the solar spectrum. Various strategies such as the optimization of the doping concentrations, Ge contents in Si1-xGex buffer layer, incorporation of the absorber layers and surface texturing have been in used to improve overall conversion efficiencies of the solar cells. To be more specific, the observed improvement in the conversion efficiency of these solar cells has been calculated by tailoring the thickness of the buffer, absorber, and emitter layers. In brief, an approach relying on the phenomena of improved absorption of the buffer and absorber layer which leads to a corresponding gain in the open circuit voltage and short circuit current is explored. For numerical analysis, a PC1D simulator is employed that uses finite element analysis technique for solving semiconductor transport equations. A comparative study of the Si/Si1-xGex and Ge/Si1-xGex is also performed. We found that due to the higher lattice mismatch of Ge to Si, thin-film solar cells based on Si/Si1-xGex heterostructures performed much better. It has been found that microc-Si and nc-Si pin structures have strong dependence on their grain sizes and crystallinity to enhance the light absorption capability of these solar cells. Our results show that silicon based thin-film solar cells exhibit high level of performance making them very competitive for the next generation of low cost photovoltaic technology.

Vapour phase techniques for deposition of CZTS thin films: A review

NASA Astrophysics Data System (ADS)

Kaur, Ramanpreet; Kumar, Sandeep; Singh, Sukhpal

2018-05-01

With the surge of thin film photovoltaic technologies in recent years, for cost reduction and increased production there is a need for earth abundant and non-toxic raw materials. Existing thin film solar cells comprising CuInS2 (CIS), CuInGaSe2 (CIGS) and CdTe contain elements that are rare in earth's crust and in case of CdTe toxic. Cu2ZnSnS4 (CZTS), having Kesterite structure, a direct band gap of 1.4 - 1.5 eV and an absorption coefficient of 104 cm-1 makes a promising candidate for absorber layer in thin film solar cells. So far many physical and chemical techniques have been employed for deposition of CZTS thin films. This review focuses on various vapour phase techniques used for fabrication of films, recent advances in these techniques and their future outlook.

Solution-Processed Cu2ZnSn(S,Se) 4 Thin-Film Solar Cells Using Elemental Cu, Zn, Sn, S, and Se Powders as Source.

PubMed

Guo, Jing; Pei, Yingli; Zhou, Zhengji; Zhou, Wenhui; Kou, Dongxing; Wu, Sixin

2015-12-01

Solution-processed approach for the deposition of Cu2ZnSn (S,Se)4 (CZTSSe) absorbing layer offers a route for fabricating thin film solar cell that is appealing because of simplified and low-cost manufacturing, large-area coverage, and better compatibility with flexible substrates. In this work, we present a simple solution-based approach for simultaneously dissolving the low-cost elemental Cu, Zn, Sn, S, and Se powder, forming a homogeneous CZTSSe precursor solution in a short time. Dense and compact kesterite CZTSSe thin film with high crystallinity and uniform composition was obtained by selenizing the low-temperature annealed spin-coated precursor film. Standard CZTSSe thin film solar cell based on the selenized CZTSSe thin film was fabricated and an efficiency of 6.4 % was achieved.

Determination of radiolysis products in gamma-irradiated multilayer barrier food packaging films containing a middle layer of recycled LDPE

NASA Astrophysics Data System (ADS)

Chytiri, Stavroula; Goulas, Antonios E.; Badeka, Anastasia; Riganakos, Kyriakos A.; Petridis, Dimitrios; Kontominas, Michael G.

2008-09-01

Volatile and non-volatile radiolysis products and sensory changes of five-layer food packaging films have been determined after gamma irradiation (5-60 kGy). Barrier films were based on polyamide (PA) and low-density polyethylene (LDPE). Each film contained a middle buried layer of recycled LDPE or 100% virgin LDPE (control samples). Data showed that a large number of radiolysis products were produced such as hydrocarbons, alcohols, carbonyl compounds, carboxylic acid. These compounds were detected in the food simulant after contact with all films even at the lower absorbed doses of 5 and 10 kGy. The type and concentration of radiolysis products increased progressively with radiation dose, while no new compounds were detected as a result of the presence of recycled LDPE. In addition, irradiation dose appears to influence the sensory properties of table water in contact with films.

Magnetic glass-film based on single-nanosize 𝜺 -Fe2O3 nanoparticles

NASA Astrophysics Data System (ADS)

Yoshikiyo, Marie; Namai, Asuka; Nakagawa, Kosuke; Ohkoshi, Shin-ichi

2017-05-01

We report a magnetic thin film of single-nanosize ɛ-Fe2O3 in SiO2 matrix. The glass-film was prepared by sintering a silica coated iron oxide hydroxide on a quartz substrate in air. The glass-film consists of ɛ-Fe2O3 of 8.8 nm size, and its thickness was 570 nm (0.57 μm) with a roughness of 10 nm (0.01 μm). UV-vis spectrum showed that the glass-film has small absorbance of 0.043 at 500 nm. The magneto-optical effect was investigated, and Faraday ellipticity showed a magnetic hysteresis loop with a coercive field of 3.0 ± 0.2 kOe. Furthermore, single-nanosize ɛ-Fe2O3 without silica was prepared as a reference sample, and ferroelectricity was observed. Therefore, the present thin glass-film consists of single-nanosize ferroelectric-ferromagnetic nanoparticles.

Impact of thermal annealing on optical properties of vacuum evaporated CdTe thin films for solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chander, Subhash, E-mail: sckhurdra@gmail.com; Purohit, A.; Lal, C.

2016-05-06

In this paper, the impact of thermal annealing on optical properties of cadmium telluride (CdTe) thin films is investigated. The films of thickness 650 nm were deposited on thoroughly cleaned glass substrate employing vacuum evaporation followed by thermal annealing in the temperature range 250-450 °C. The as-deposited and annealed films were characterized using UV-Vis spectrophotometer. The optical band gap is found to be decreased from 1.88 eV to 1.48 eV with thermal annealing. The refractive index is found to be in the range 2.73-2.92 and observed to increase with annealing treatment. The experimental results reveal that the thermal annealing plays anmore » important role to enhance the optical properties of CdTe thin films and annealed films may be used as absorber layer in CdTe/CdS solar cells.« less

The Cu2ZnSnSe4 thin films solar cells synthesized by electrodeposition route

NASA Astrophysics Data System (ADS)

Li, Ji; Ma, Tuteng; Wei, Ming; Liu, Weifeng; Jiang, Guoshun; Zhu, Changfei

2012-06-01

An electrodeposition route for preparing Cu2ZnSnSe4 thin films for thin film solar cell absorber layers is demonstrated. The Cu2ZnSnSe4 thin films are prepared by co-electrodeposition Cu-Zn-Sn metallic precursor and subsequently annealing in element selenium atmosphere. The structure, composition and optical properties of the films were investigated by X-ray diffraction (XRD), Raman spectrometry, energy dispersive spectrometry (EDS) and UV-VIS absorption spectroscopy. The Cu2ZnSnSe4 thin film with high crystalline quality was obtained, the band gap and absorption coefficient were 1.0 eV and 10-4 cm-1, which is quite suitable for solar cells fabrication. A solar cell with the structure of ZnO:Al/i-ZnO/CdS/Cu2ZnSnSe4/Mo/glass was fabricated and achieved an conversion efficiency of 1.7%.

The effect of Na on Cu-K-In-Se thin film growth

NASA Astrophysics Data System (ADS)

Muzzillo, Christopher P.; Tong, Ho Ming; Anderson, Timothy J.

2018-04-01

Co-evaporation of Cu-KF-In-Se was performed on substrates with varied Na supply. Compositions of interest for photovoltaic absorbers were studied, with ratios of (K + Cu)/In ∼ 0.85 and K/(K + Cu) ∼ 0-0.57. Bare soda-lime glass (SLG) substrates had the highest Na supply as measured by secondary ion mass spectrometry, while SLG/Mo and SLG/SiO2/Mo substrates led to 3x and 3000x less Na in the growing film, respectively. Increased Na supply favored Cu1-xKxInSe2 (CKIS) alloy formation as proven by X-ray diffraction (XRD), while decreased Na supply favored the formation of CuInSe2 + KInSe2 mixed-phase films. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed the KInSe2 precipitates to be readily recognizable planar crystals. Extrinsic KF addition during film growth promoted diffusion of Na out from the various substrates and into the growing film, in agreement with previous reports. Time-resolved photoluminescence showed enhanced minority carrier lifetimes for films with moderate K compositions (0.04 < K/(K + Cu) < 0.14) grown on SLG/Mo. Due to the relatively high detection limit of KInSe2 by XRD and the low magnitude of chalcopyrite lattice shift for CKIS alloys with these compositions, it is unclear if the lifetime gains were associated with CKIS alloying, minor KInSe2 content, or both. The identified Na-K interdependency can be used to engineer alkali metal bonding in Cu(In,Ga)(Se,S)2 absorbers to optimize both initial and long-term photovoltaic power generation.

Graphene doped ZnO films for photoelectrowetting on microchannels

NASA Astrophysics Data System (ADS)

Al-Aribe, Khaled; Knopf, George K.

2017-02-01

Photoelectrowetting on dielectric surfaces can be used to drive droplets of liquid along reconfigurable paths on a microfluidic chip using controlled optical signals. These electrostatically activated surfaces along the desired path eliminate the need for precision molded channels and discrete functional components such as microvalves and micropumps. The photoelectrowetting effect exploits the surface tension of the droplet to maintain its volume during the transportation pathway and the photoelectric properties of the substrate surface are used to induce reversible fluidic flow. The active light-driven substrate is structured from graphene doped zinc-oxide (ZnO-G) films deposited on ITO coated glass. This substrate is coated from the ZnO-G side with Ruthenium-based dye (N719) to maximize its absorbability. The light triggers two forces that enable the droplet to be transported along the substrate. The first arises from the induced hydrophobicity gradient formed across the droplet contact area with the substrate surface. Exposing the ZnO-G film to a broad spectrum white light source alters the surface's electric potential which induces a change in the droplet's contact angle and the associated hydrophobicity. Once the hydrophobicity gradient is generated the droplet will start to move in the direction of the wetting zone. The second force is also created by the optical input when the absorbed light generates a photoelectric potential that produces a piezo-electrical effect on the ZnO-G film. The light triggered piezo-electrical behavior of the ZnO-G film can be used to generate the erasable microchannels that can guide droplet movement through a microfluidic chip. Preliminary experiments are performed to investigate the photoelectric potential of light activated ZnO-G films.

The effect of Na on Cu-K-In-Se thin film growth

DOE PAGES

Muzzillo, Christopher P.; Tong, Ho Ming; Anderson, Timothy J.

2018-02-27

Co-evaporation of Cu-KF-In-Se was performed on substrates with varied Na supply. Compositions of interest for photovoltaic absorbers were studied, with ratios of (K + Cu)/In ~ 0.85 and K/(K + Cu) ~ 0-0.57. Bare soda-lime glass (SLG) substrates had the highest Na supply as measured by secondary ion mass spectrometry, while SLG/Mo and SLG/SiO 2/Mo substrates led to 3x and 3000x less Na in the growing film, respectively. Increased Na supply favored Cu 1-xK xInSe 2 (CKIS) alloy formation as proven by X-ray diffraction (XRD), while decreased Na supply favored the formation of CuInSe 2 + KInSe 2 mixed-phase films.more » Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed the KInSe 2 precipitates to be readily recognizable planar crystals. Extrinsic KF addition during film growth promoted diffusion of Na out from the various substrates and into the growing film, in agreement with previous reports. Time-resolved photoluminescence showed enhanced minority carrier lifetimes for films with moderate K compositions (0.04 < K/(K + Cu) < 0.14) grown on SLG/Mo. Due to the relatively high detection limit of KInSe 2 by XRD and the low magnitude of chalcopyrite lattice shift for CKIS alloys with these compositions, it is unclear if the lifetime gains were associated with CKIS alloying, minor KInSe 2 content, or both. The identified Na-K interdependency can be used to engineer alkali metal bonding in Cu(In,Ga)(Se,S) 2 absorbers to optimize both initial and long-term photovoltaic power generation.« less

The effect of Na on Cu-K-In-Se thin film growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muzzillo, Christopher P.; Tong, Ho Ming; Anderson, Timothy J.

Co-evaporation of Cu-KF-In-Se was performed on substrates with varied Na supply. Compositions of interest for photovoltaic absorbers were studied, with ratios of (K + Cu)/In ~ 0.85 and K/(K + Cu) ~ 0-0.57. Bare soda-lime glass (SLG) substrates had the highest Na supply as measured by secondary ion mass spectrometry, while SLG/Mo and SLG/SiO 2/Mo substrates led to 3x and 3000x less Na in the growing film, respectively. Increased Na supply favored Cu 1-xK xInSe 2 (CKIS) alloy formation as proven by X-ray diffraction (XRD), while decreased Na supply favored the formation of CuInSe 2 + KInSe 2 mixed-phase films.more » Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed the KInSe 2 precipitates to be readily recognizable planar crystals. Extrinsic KF addition during film growth promoted diffusion of Na out from the various substrates and into the growing film, in agreement with previous reports. Time-resolved photoluminescence showed enhanced minority carrier lifetimes for films with moderate K compositions (0.04 < K/(K + Cu) < 0.14) grown on SLG/Mo. Due to the relatively high detection limit of KInSe 2 by XRD and the low magnitude of chalcopyrite lattice shift for CKIS alloys with these compositions, it is unclear if the lifetime gains were associated with CKIS alloying, minor KInSe 2 content, or both. The identified Na-K interdependency can be used to engineer alkali metal bonding in Cu(In,Ga)(Se,S) 2 absorbers to optimize both initial and long-term photovoltaic power generation.« less

Development and characterization of a three-dimensional radiochromic film stack dosimeter for megavoltage photon beam dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCaw, Travis J., E-mail: mccaw@wisc.edu; Micka, John A.; DeWerd, Larry A.

Purpose: Three-dimensional (3D) dosimeters are particularly useful for verifying the commissioning of treatment planning and delivery systems, especially with the ever-increasing implementation of complex and conformal radiotherapy techniques such as volumetric modulated arc therapy. However, currently available 3D dosimeters require extensive experience to prepare and analyze, and are subject to large measurement uncertainties. This work aims to provide a more readily implementable 3D dosimeter with the development and characterization of a radiochromic film stack dosimeter for megavoltage photon beam dosimetry. Methods: A film stack dosimeter was developed using Gafchromic{sup ®} EBT2 films. The dosimeter consists of 22 films separated bymore » 1 mm-thick spacers. A Virtual Water™ phantom was created that maintains the radial film alignment within a maximum uncertainty of 0.3 mm. The film stack dosimeter was characterized using simulations and measurements of 6 MV fields. The absorbed-dose energy dependence and orientation dependence of the film stack dosimeter were investigated using Monte Carlo simulations. The water equivalence of the dosimeter was determined by comparing percentage-depth-dose (PDD) profiles measured with the film stack dosimeter and simulated using Monte Carlo methods. Film stack dosimeter measurements were verified with thermoluminescent dosimeter (TLD) microcube measurements. The film stack dosimeter was also used to verify the delivery of an intensity-modulated radiation therapy (IMRT) procedure. Results: The absorbed-dose energy response of EBT2 film differs less than 1.5% between the calibration and film stack dosimeter geometries for a 6 MV spectrum. Over a series of beam angles ranging from normal incidence to parallel incidence, the overall variation in the response of the film stack dosimeter is within a range of 2.5%. Relative to the response to a normally incident beam, the film stack dosimeter exhibits a 1% under-response when the beam axis is parallel to the film planes. Measured and simulated PDD profiles agree within a root-mean-square difference of 1.3%. In-field film stack dosimeter and TLD measurements agree within 5%, and measurements in the field penumbra agree within 0.5 mm. Film stack dosimeter and TLD measurements have expanded (k = 2) overall measurement uncertainties of 6.2% and 5.8%, respectively. Film stack dosimeter measurements of an IMRT dose distribution have 98% agreement with the treatment planning system dose calculation, using gamma criteria of 3% and 2 mm. Conclusions: The film stack dosimeter is capable of high-resolution, low-uncertainty 3D dose measurements, and can be readily incorporated into an existing film dosimetry program.« less

Tuning Bandgap of p-Type Cu2Zn(Sn, Ge)(S, Se)4 Semiconductor Thin Films via Aqueous Polymer-Assisted Deposition.

PubMed

Yi, Qinghua; Wu, Jiang; Zhao, Jie; Wang, Hao; Hu, Jiapeng; Dai, Xiao; Zou, Guifu

2017-01-18

Bandgap engineering of kesterite Cu 2 Zn(Sn, Ge)(S, Se) 4 with well-controlled stoichiometric composition plays a critical role in sustainable inorganic photovoltaics. Herein, a cost-effective and reproducible aqueous solution-based polymer-assisted deposition approach is developed to grow p-type Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films with tunable bandgap. The bandgap of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films can be tuned within the range 1.05-1.95 eV using the aqueous polymer-assisted deposition by accurately controlling the elemental compositions. One of the as-grown Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films exhibits a hall coefficient of +137 cm 3 /C. The resistivity, concentration and carrier mobility of the Cu 2 ZnSn(S, Se) 4 thin film are 3.17 ohm·cm, 4.5 × 10 16 cm -3 , and 43 cm 2 /(V·S) at room temperature, respectively. Moreover, the Cu 2 ZnSn(S, Se) 4 thin film when used as an active layer in a solar cell leads to a power conversion efficiency of 3.55%. The facile growth of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films in an aqueous system, instead of organic solvents, provides great promise as an environmental-friendly platform to fabricate a variety of single/multi metal chalcogenides for the thin film industry and solution-processed photovoltaic devices.

Evaluation of the Propensity of Niobium to Absorb Hydrogen During Fabrication of Superconducting Radio Frequency Cavities for Particle Accelerators

PubMed Central

Ricker, R. E.; Myneni, G. R.

2010-01-01

During the fabrication of niobium superconducting radio frequency (SRF) particle accelerator cavities procedures are used that chemically or mechanically remove the passivating surface film of niobium pentoxide (Nb2O5). Removal of this film will expose the underlying niobium metal and allow it to react with the processing environment. If these reactions produce hydrogen at sufficient concentrations and rates, then hydrogen will be absorbed and diffuse into the metal. High hydrogen activities could result in supersaturation and the nucleation of hydride phases. If the metal repassivates at the conclusion of the processing step and the passive film blocks hydrogen egress, then the absorbed hydrogen or hydrides could be retained and alter the performance of the metal during subsequent processing steps or in-service. This report examines the feasibility of this hypothesis by first identifying the postulated events, conditions, and reactions and then determining if each is consistent with accepted scientific principles, literature, and data. Established precedent for similar events in other systems was found in the scientific literature and thermodynamic analysis found that the postulated reactions were not only energetically favorable, but produced large driving forces. The hydrogen activity or fugacity required for the reactions to be at equilibrium was determined to indicate the propensity for hydrogen evolution, absorption, and hydride nucleation. The influence of processing conditions and kinetics on the proximity of hydrogen surface coverage to these theoretical values is discussed. This examination found that the hypothesis of hydrogen absorption during SRF processing is consistent with published scientific literature and thermodynamic principles. PMID:27134791

Dose perturbation due to the presence of a prostatic urethral stent in patients receiving pelvic radiotherapy: an in vitro study.

PubMed

Gez, E; Cederbaum, M; Yachia, D; Bar-Deroma, R; Kuten, A

1997-01-01

Temporary metallic intraprostatic stent is a new alternative treatment for patients with urinary obstructive syndrome caused by prostate cancer. Definitive radiotherapy is a treatment of choice for localized prostate cancer. This study evaluates in vitro the effect of a urethral intraprostatic metallic stent on the dose absorbed by the surrounding tissue. The study was designed to mimic the conditions under which the prostatic stent is placed in the body during pelvic irradiation. A urethral stent composed of a 50% nickel-50% titanium alloy (Uracoil-InStent) was imbedded in material mimicking normal tissue (bolus) at a simulated body depth of 10 cm. The distribution of the absorbed dose of irradiation was determined by film dosimetry using Kodak X-Omat V film. Irradiation was done in a single field at the isocenter of a 6 MV linear accelerator with a field size of 7 x 7 cm. The degree of film blackening was in direct proportion to the absorbed dose. The measurements showed an increase in dose of up to 20% immediately before the stent and a decrease of up to 18% immediately after the stent. These changes occurred within a range of 1-3 mm from both sides of the stent. In practice, irradiation in prostate cancer is given by two pairs of opposed co-axial fields; a total of four fields (Box Technique). The dose perturbations are partly cancelled in a pair of opposed beams resulting in a net variation of +/- 4%; therefore, the presence of the intraprostatic stent should not influence radiotherapy planning for prostate cancer.

Fabrication and comparison of selective, transparent optics for concentrating solar systems

NASA Astrophysics Data System (ADS)

Taylor, Robert A.; Hewakuruppu, Yasitha; DeJarnette, Drew; Otanicar, Todd P.

2015-09-01

Concentrating optics enable solar thermal energy to be harvested at high temperature (<100oC). As the temperature of the receiver increases, radiative losses can become dominant. In many concentrating systems, the receiver is coated with a selectively absorbing surface (TiNOx, Black Chrome, etc.) to obtain higher efficiency. Commercial absorber coatings are well-developed to be highly absorbing for short (solar) wavelengths, but highly reflective at long (thermal emission) wavelengths. If a solar system requires an analogous transparent, non-absorbing optic - i.e. a cover material which is highly transparent at short wavelengths, but highly reflective at long wavelengths - the technology is simply not available. Low-e glass technology represents a commercially viable option for this sector, but it has only been optimized for visible light transmission. Optically thin metal hole-arrays are another feasible solution, but are often difficult to fabricate. This study investigates combinations of thin film coatings of transparent conductive oxides and nanoparticles as a potential low cost solution for selective solar covers. This paper experimentally compares readily available materials deposited on various substrates and ranks them via an `efficiency factor for selectivity', which represents the efficiency of radiative exchange in a solar collector. Out of the materials studied, indium tin oxide and thin films of ZnS-Ag-ZnS represent the most feasible solutions for concentrated solar systems. Overall, this study provides an engineering design approach and guide for creating scalable, selective, transparent optics which could potentially be imbedded within conventional low-e glass production techniques.

Magneto-optical Kerr rotation and color in ultrathin lossy dielectric

NASA Astrophysics Data System (ADS)

Zhang, Jing; Wang, Hai; Qu, Xin; Zhou, Yun song; Li, Li na

2017-05-01

Ultra-thin optical coating comprising nanometer-thick silicon absorbing films on iron substrates can display strong optical interference effects. A resonance peak of ∼1.6^\\circ longitudinal Kerr rotation with the silicon thickness of ∼47 \\text{nm} was found at the wavelength of 660 nm. The optical properties of silicon thin films were well controlled by the sputtering power. Non-iridescence color exhibition and Kerr rotation enhancement can be manipulated and encoded individually.

Studies of the Superconducting Transition in the Mo/Au-Bilayer Thin Films

NASA Technical Reports Server (NTRS)

Sadleir, John; Smith, Stephen; Iyomoto, naoko; Bandler, Simon; Chervenak, Jay; Brown, Ari; Brekowsky, Regis; Kilbourne, Caroline; Robinson, Ian

2007-01-01

At NASA Goddard, microcalorimeter arrays using superconducting transition edge sensor thermometers (TESs) are under development for high energy resolution X-ray astrophysics applications. We report on our studies of the superconducting transition in our Mo/Au-bilayer TES films including: low current measurements of the superconducting bilayer's resistance transition versus temperature on pixels with different normal metal absorber attachment designs and measured temperature scaling of the critical current and critical magnetic field.

MAPbI2.9-xBrxCl0.1 hybrid halide perovskites: Shedding light on the effect of chloride and bromide ions on structural and photoluminescence properties

NASA Astrophysics Data System (ADS)

Atourki, Lahoucine; Vega, Erika; Marí, Bernabé; Mollar, Miguel; Ait Ahsaine, Hassan; Bouabid, Khalid; Ihlal, Ahmed

2016-12-01

The optical and structural properties of CH3NH3PbI3 can be adjusted by introducing other extrinsic ions such as chloride and bromide. In this work, mixed bromide iodide lead perovskites with a 10% fraction of chloride were prepared from methylamine, lead nitrate and the corresponding hydro acid (X = I, Br, Cl). The effect of bromide and chloride incorporation on different properties of perovskite thin film was investigated. The Pawley fit method indicates the formation of the iodide halide MAPbI3 Pm-3 m cubic phase for x = 0 and the tetragonal P4/mmm phase for x ≥ 0.3. All deposited films showed a strong absorbance in the UV-vis range. The band gap values were estimated from absorbance measurements. It was found that the onset of the absorption edge for MAPbI2.9-xBrxCl0.1 thin film perovskites ranges between 1.60 and 1.80 eV. Moreover, it was found that both Cl and Br affect the PL emission of the mixed halide lead perovskite, the MAPbI2.9-xBrxCl0.1 films displayed intermediate values from 730 nm (MAPbI2.2Br0.7Cl0.1) to 770 nm (MAPbI2.6Br0.3Cl0.1).

Coupled optical and electrical study of thin-film InGaAs photodetector integrated with surface InP Mie resonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Dong; Song, Jiakun; Yu, Hailong

2016-03-14

High-index dielectric and semiconductor nanostructures with characteristics of low absorption loss and artificially controlled scattering properties have grasped an increasing attention for improving the performance of thin-film photovoltaic devices. In this work, combined optical and electrical simulations were performed for thin-film InP/In{sub 0.53}Ga{sub 0.47}As/InP hetero-junction photodetector with periodically arranged InP nano-cylinders in the in-coupling configuration. It is found that the carefully designed InP nano-cylinders possess strongly substrate-coupled Mie resonances and can effectively couple incident light into the guided mode, both of which significantly increase optical absorption. Further study from the electrical aspects shows that enhancement of external quantum efficiency ismore » as high as 82% and 83% in the configurations with the optimized nano-cylinders and the optimized period, respectively. Moreover, we demonstrate that the integration of InP nano-cylinders does not degrade the electrical performance, since the surface recombination is effectively suppressed by separating the absorber layer where carriers generate and the air/semiconductor interface. The comprehensive modeling including optical and electrical perspectives provides a more practical description for device performance than the optical-only simulation and is expected to advance the design of thin-film absorber layer based optoelectronic devices for fast response and high efficiency.« less

Influence of substrate temperature on properties of MgF 2 coatings

NASA Astrophysics Data System (ADS)

Yu, Hua; Qi, Hongji; Cui, Yun; Shen, Yanming; Shao, JianDa; Fan, ZhengXiu

2007-05-01

Thermal boat evaporation was employed to prepare MgF 2 single-layer coatings upon both JGS1 and UBK7 substrates at different substrate temperatures. Microstructure, transmittance and residual stress of these coatings were measured by X-ray diffraction, spectrophotometer, and optical interferometer, respectively. Measurement of laser induced damage threshold (LIDT) of the samples was performed at 355 nm, 8 ns pulses. The results showed that high substrate temperature was beneficial to crystallization of the film. Above 244 °C, the refractive index increased gradually with the substrate temperature rising. Whereas, it was exceptional at 210 °C that the refractive index was higher than those deposited at 244 and 277 °C. The tensile residual stresses were exhibited in all MgF 2 films, but not well correlated with the substrate temperature. In addition, the stresses were comparatively smaller upon JGS1 substrates. A tendency could be seen that the LIDTs reached the highest values at about 244 °C, and the films upon JGS1 had higher LIDTs than those upon UBK7 substrates at the same temperature. Meanwhile, the damage morphologies showed that the laser damage of the coating resulted from an absorbing center at the film-substrate interface. The features of the damages were displayed by an absorbing center dominated model. Furthermore, the reason of the difference in LIDT values was discussed in detail.

Continuous Microreactor-Assisted Solution Deposition for Scalable Production of CdS Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramprasad, Sudhir; Su, Yu-Wei; Chang, Chih-Hung

2013-06-13

Solution deposition offers an attractive, low temperature option in the cost effective production of thin film solar cells. Continuous microreactor-assisted solution deposition (MASD) was used to produce nanocrystalline cadmium sulfide (CdS) films on fluorine doped tin oxide (FTO) coated glass substrates with excellent uniformity. We report a novel liquid coating technique using a ceramic rod to efficiently and uniformly apply reactive solution to large substrates (152 mm × 152 mm). This technique represents an inexpensive approach to utilize the MASD on the substrate for uniform growth of CdS films. Nano-crystalline CdS films have been produced from liquid phase at ~90°C,more » with average thicknesses of 70 nm to 230 nm and with a 5 to 12% thickness variation. The CdS films produced were characterized by UV-Vis spectroscopy, transmission electron microscopy, and X-Ray diffraction to demonstrate their suitability to thin-film solar technology.« less

Low-temperature formation of c-axis-oriented aluminum nitride thin films by plasma-assisted reactive pulsed-DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Takenaka, Kosuke; Satake, Yoshikatsu; Uchida, Giichiro; Setsuhara, Yuichi

2018-01-01

The low-temperature formation of c-axis-oriented aluminum nitride thin films was demonstrated by plasma-assisted reactive pulsed-DC magnetron sputtering. The effects of the duty cycle at the pulsed-DC voltage applied to the Al target on the properties of AlN films formed via inductively coupled plasma (ICP)-enhanced pulsed-DC magnetron sputtering deposition were investigated. With decreasing duty cycle at the target voltage, the peak intensity of AlN(0002) increased linearly. The surface roughness of AlN films decreased since there was an increase in film density owing to the impact of energetic ions on the films together with the enhancement of nitriding associated with the relative increase in N radical flux. The improvement of both the crystallinity and surface morphology of AlN films at low temperatures is considered to be caused by the difference between the relative flux values of ions and sputtered atoms.

Photocatalytic degradation of metronidazole and methylene blue by PVA-assisted Bi2WO6-CdS nanocomposite film under visible light irradiation

NASA Astrophysics Data System (ADS)

Rajendran, Ranjith; Varadharajan, Krishnakumar; Jayaraman, Venkatesan; Singaram, Boobas; Jeyaram, Jayaprakash

2018-02-01

The enhanced photocatalytic performance of nanocomposite is synthesized via the hydrothermal method and characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence spectroscopy (PL). Under visible light irradiation, PVA assisted Bi2WO6-CdS nanocomposite film displayed enhanced photocatalytic efficiency and inhibition of photocorrosion as compared with pure CdS, pure Bi2WO6 and Bi2WO6-CdS composite. The PVA assisted Bi2WO6-CdS composite film catalyst showed stable catalytic performance until seven successive runs with 92% of methylene blue(MB) degradation, and easy to recover after degradation of organic pollutant. PVA assisted Bi2WO6-CdS nanocomposite film has optimal band edge position for superior photocatalytic degradation. Furthermore, the trapping experiment was carried out using different scavenger for active species. Among the active species, OH· are the most responsive species which play a vital role in the degradation of metronidazole and MB.

Substrate-biasing during plasma-assisted atomic layer deposition to tailor metal-oxide thin film growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Profijt, H. B.; Sanden, M. C. M. van de; Kessels, W. M. M.

2013-01-15

Two substrate-biasing techniques, i.e., substrate-tuned biasing and RF biasing, have been implemented in a remote plasma configuration, enabling control of the ion energy during plasma-assisted atomic layer deposition (ALD). With both techniques, substrate bias voltages up to -200 V have been reached, which allowed for ion energies up to 272 eV. Besides the bias voltage, the ion energy and the ion flux, also the electron temperature, the electron density, and the optical emission of the plasma have been measured. The effects of substrate biasing during plasma-assisted ALD have been investigated for Al{sub 2}O{sub 3}, Co{sub 3}O{sub 4}, and TiO{sub 2}more » thin films. The growth per cycle, the mass density, and the crystallinity have been investigated, and it was found that these process and material properties can be tailored using substrate biasing. Additionally, the residual stress in substrates coated with Al{sub 2}O{sub 3} films varied with the substrate bias voltage. The results reported in this article demonstrate that substrate biasing is a promising technique to tailor the material properties of thin films synthesized by plasma-assisted ALD.« less