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Sample records for ag photon solar

  1. Ag nanocluster functionalized glasses for efficient photonic conversion in light sources, solar cells and flexible screen monitors.

    PubMed

    Kuznetsov, A S; Tikhomirov, V K; Shestakov, M V; Moshchalkov, V V

    2013-11-01

    An ever growing demand for efficient energy conversion, for instance in luminescent lamps, flexible screens and solar cells, results in the current significant growth of research on functionalized nanomaterials for these applications. This paper reviews recent developments of a new class of optically active nanostructured materials based on glasses doped with luminescent Ag nanoclusters consisting of only a few Ag atoms, suitable for mercury-free white light generation and solar down-shifting. This new approach, based solely on Ag nanocluster doped glasses, is compared to other alternatives in the field of Ag and rare-earth ion co-doped materials. PMID:23948871

  2. Ag nanocluster functionalized glasses for efficient photonic conversion in light sources, solar cells and flexible screen monitors

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. S.; Tikhomirov, V. K.; Shestakov, M. V.; Moshchalkov, V. V.

    2013-10-01

    An ever growing demand for efficient energy conversion, for instance in luminescent lamps, flexible screens and solar cells, results in the current significant growth of research on functionalized nanomaterials for these applications. This paper reviews recent developments of a new class of optically active nanostructured materials based on glasses doped with luminescent Ag nanoclusters consisting of only a few Ag atoms, suitable for mercury-free white light generation and solar down-shifting. This new approach, based solely on Ag nanocluster doped glasses, is compared to other alternatives in the field of Ag and rare-earth ion co-doped materials.

  3. Holographic Solar Photon Thrusters

    NASA Technical Reports Server (NTRS)

    Johnson, Les; Matloff, Greg

    2006-01-01

    A document discusses a proposal to incorporate holographic optical elements into solar photon thrusters (SPTs). First suggested in 1990, SPTs would be systems of multiple reflective, emissive, and absorptive surfaces (solar sails) that would be attached to spacecraft orbiting the Earth to derive small propulsive forces from radiation pressures. An SPT according to the proposal would include, among other things, a main sail. One side of the sail would be highly emissive and would normally face away from the Earth. The other side would be reflective and would be covered by white-light holographic images that would alternately become reflective, transmissive, and absorptive with small changes in the viewing angle. When the spacecraft was at a favorable orbital position, the main sail would be oriented to reflect sunlight in a direction to maximize the solar thrust; when not in a favorable position, the main sail would be oriented to present a substantially absorptive/emissive aspect to minimize the solar drag. By turning the main sail slightly to alternate between the reflective and absorptive/ emissive extremes, one could achieve nearly a doubling or halving of the radiational momentum transfer and, hence, of the solar thrust.

  4. Introduction to Solar Photon Conversion

    SciTech Connect

    Nozik, Arthur J; Miller, John

    2010-11-10

    This Thematic Issue on Solar Photon Conversion will provide a review by leading researchers on the present status and prognosis of the science and technology of direct solar photoconversion to electricity and fuels. The topics covered include advanced and novel concepts for low-cost photovoltaic (PV) energy based on chemistry (dye-sensitized photoelectrodes, organic and molecular PV, multiple exciton generation in quantum dots, singlet fission), solar water splitting, redox catalysis for water oxidation and reduction, the role of nanoscience and nanocrystals in solar photoconversion, photoelectrochemical energy conversion, and photoinduced electron transfer.

  5. Introduction to Solar Photon Conversion

    SciTech Connect

    Nozik, A.; Miller, J.

    2010-11-10

    The efficient and cost-effective direct conversion of solar photons into solar electricity and solar fuels is one of the most important scientific and technological challenges of this century. It is estimated that at least 20 terawatts of carbon-free energy (1 and 1/2 times the total amount of all forms of energy consumed today globally), in the form of electricity and liquid and gaseous fuels, will be required by 2050 in order to avoid the most serious consequences of global climate change and to ensure adequate global energy supply that will avoid economic chaos. But in order for solar energy to contribute a major fraction of future carbon-free energy supplies, it must be priced competitively with, or perhaps even be less costly than, energy from fossil fuels and nuclear power as well as other renewable energy resources. The challenge of delivering very low-cost solar fuels and electricity will require groundbreaking advances in both fundamental and applied science. This Thematic Issue on Solar Photon Conversion will provide a review by leading researchers on the present status and prognosis of the science and technology of direct solar photoconversion to electricity and fuels. The topics covered include advanced and novel concepts for low-cost photovoltaic (PV) energy based on chemistry (dye-sensitized photoelectrodes, organic and molecular PV, multiple exciton generation in quantum dots, singlet fission), solar water splitting, redox catalysis for water oxidation and reduction, the role of nanoscience and nanocrystals in solar photoconversion, photoelectrochemical energy conversion, and photoinduced electron transfer. The direct conversion of solar photons to electricity via photovoltaic (PV) cells is a vital present-day commercial industry, with PV module production growing at about 75%/year over the past 3 years. However, the total installed yearly averaged energy capacity at the end of 2009 was about 7 GW-year (0.2% of global electricity usage). Thus, there

  6. Apollony photonic sponge based photoelectrochemical solar cells.

    PubMed

    Ramiro-Manzano, Fernando; Atienzar, Pedro; Rodriguez, Isabelle; Meseguer, Francisco; Garcia, Hermenegildo; Corma, Avelino

    2007-01-21

    We have developed a quasi-fractal colloidal crystal to localize efficiently photons in a very broad optical spectral range; it has been applied to prepare dye sensitized photoelectrochemical solar (PES) cells able to harvest very efficiently photons from the ultraviolet (UV) and the visible (VIS) regions of the solar spectrum. PMID:17299626

  7. Near infrared emission of TbAG:Ce3+,Yb3+ phosphor for solar cell applications

    NASA Astrophysics Data System (ADS)

    Meshram, N. D.; Yadav, P. J.; Pathak, A. A.; Joshi, C. P.; Moharil, S. V.

    2016-05-01

    Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimated to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr3+, Gd3+,Gd3+-Eu3+, and Er3+-Tb3+ had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb3+-Yb3+, Pr3+-Yb3+, and Tm3+-Yb3+ has been reported. The Yb3+ ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb3+ is close to 100% and the energy of the only excited level of Yb3+ (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce3+-doped Tb3Al5O12 (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300-500 nm due to strong ligand field and high luminescent quantum efficiency. Therefore, the Ce3+ ions in the TbAG can be suitable as an excellent sensitizing donor for down conversion materials of Si solar cells. In this

  8. Reversibly phototunable TiO{sub 2} photonic crystal modulated by Ag nanoparticles' oxidation/reduction

    SciTech Connect

    Liu Jian; Zhou Jinming; Ye Changqing; Li Mingzhu; Wang Jingxia; Jiang Lei; Song Yanlin

    2011-01-10

    We report a reversibly phototunable photonic crystal system whose reflectance at the stop band position can be modulated by alternating UV/visible (UV/Vis) irradiation. The phototunable system consists of Ag nanoparticles and TiO{sub 2} photonic crystal. The stop bands intensity of Ag loaded TiO{sub 2} photonic crystals were found to be dependent on the redox states of Ag nanoparticles. The quasi 'on' and 'off' states of the stop band were reversibly modulated by the Ag nanoparticles' oxidation/reduction through alternating UV/Vis light irradiation.

  9. Solar photons, phonons and neutrinos

    NASA Astrophysics Data System (ADS)

    Chitre, S. M.

    1998-06-01

    The inside of the Sun is not directly accessible to observations. Nonetheless, it is possible to construct a reasonable picture of its interior with the help of the theory of stellar structure along with the input physics describing a multitude of processes occurring inside the Sun. In order to check the validity of these theoretical models there have been valiant attempts to measure the flux of neutrinos generated in the Sun's energy-generating core. The solar neutrino event rates reported by all the experiments to date have been consistently lower than those predicted by standard solar models. There is now a complementary probe, furnished by the accurately measured helioseismic data which provides stringent constraints on the physical conditions prevailing inside the Sun. It turns out that the helioseismically inferred density and sound speed profiles throughout the Sun's internal layers are close to those obtained with a standard solar model. A cooler solar core is, therefore, not a viable solution to account for the deficit in the measured neutrino fluxes. This leads one to the unavoidable conclusion that the solution to the solar neutrino puzzle should be sought in the realm of particle physics.

  10. Ag-In-Zn-S quantum dots for hybrid organic-inorganic solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Eung-min; Ruankham, Pipat; Lee, Jae-hyeong; Hachiya, Kan; Sagawa, Takashi

    2016-02-01

    Quantum dots of (AgIn)xZn2(1-x)S2 (x = 0.6, 0.8, and 1.0) capped by oleylamine were prepared and applied for hybrid organic-inorganic solar cells consisting of glass-indium-tin-oxide/ZnO/(AgIn)xZn2(1-x)S2/poly(3-hexylthiophene)/MoO3/Ag. The short-circuit current density (Jsc) and open-circuit voltage (Voc) of the hybrid solar cells were measured, and we found a low power conversion efficiency (PCE) below 0.1%. From the incident photon-to-current efficiency (IPCE) profiles of the hybrid devices, there is no marked photocurrent generation from 350 to 700 nm, which is ascribed to the absorption region of (AgIn)xZn2(1-x)S2. To improve the photovoltaic performance, ligand substitution from oleylamine to pyridine was performed. The PCE of the hybrid cell using the pyridine-capped (AgIn)xZn2(1-x)S2 was improved twofold in terms of both Jsc and Voc as compared with that of the oleylamine-capped one. In particular, from the IPCE measurements, a remarkable (more than doubled) enhancement of photocurrent generation from 400 to 450 nm was observed with the pyridine-substituted nanoparticles.

  11. Template-Directed Directionally Solidified 3D Mesostructured AgCl-KCl Eutectic Photonic Crystals.

    PubMed

    Kim, Jinwoo; Aagesen, Larry K; Choi, Jun Hee; Choi, Jaewon; Kim, Ha Seong; Liu, Jinyun; Cho, Chae-Ryong; Kang, Jin Gu; Ramazani, Ali; Thornton, Katsuyo; Braun, Paul V

    2015-08-19

    3D mesostructured AgCl-KCl photonic crystals emerge from colloidal templating of eutectic solidification. Solvent removal of the KCl phase results in a mesostructured AgCl inverse opal. The 3D-template-induced confinement leads to the emergence of a complex microstructure. The 3D mesostructured eutectic photonic crystals have a large stop band ranging from the near-infrared to the visible tuned by the processing. PMID:26177830

  12. Atlas of solar hidden photon emission

    NASA Astrophysics Data System (ADS)

    Redondo, Javier

    2015-07-01

    Hidden photons, gauge bosons of a U(1) symmetry of a hidden sector, can constitute the dark matter of the universe and a smoking gun for large volume compactifications of string theory. In the sub-eV mass range, a possible discovery experiment consists on searching the copious flux of these particles emitted from the Sun in a helioscope setup à la Sikivie. In this paper, we compute in great detail the flux of HPs from the Sun, a necessary ingredient for interpreting such experiments. We provide a detailed exposition of transverse photon-HP oscillations in inhomogenous media, with special focus on resonance oscillations, which play a leading role in many cases. The region of the Sun emitting HPs resonantly is a thin spherical shell for which we justify an averaged-emission formula and which implies a distinctive morphology of the angular distribution of HPs on Earth in many cases. Low mass HPs with energies in the visible and IR have resonances very close to the photosphere where the solar plasma is not fully ionised and requires building a detailed model of solar refraction and absorption. We present results for a broad range of HP masses (from 0-1 keV) and energies (from the IR to the X-ray range), the most complete atlas of solar HP emission to date.

  13. Atlas of solar hidden photon emission

    SciTech Connect

    Redondo, Javier

    2015-07-20

    Hidden photons, gauge bosons of a U(1) symmetry of a hidden sector, can constitute the dark matter of the universe and a smoking gun for large volume compactifications of string theory. In the sub-eV mass range, a possible discovery experiment consists on searching the copious flux of these particles emitted from the Sun in a helioscope setup à la Sikivie. In this paper, we compute in great detail the flux of HPs from the Sun, a necessary ingredient for interpreting such experiments. We provide a detailed exposition of transverse photon-HP oscillations in inhomogenous media, with special focus on resonance oscillations, which play a leading role in many cases. The region of the Sun emitting HPs resonantly is a thin spherical shell for which we justify an averaged-emission formula and which implies a distinctive morphology of the angular distribution of HPs on Earth in many cases. Low mass HPs with energies in the visible and IR have resonances very close to the photosphere where the solar plasma is not fully ionised and requires building a detailed model of solar refraction and absorption. We present results for a broad range of HP masses (from 0–1 keV) and energies (from the IR to the X-ray range), the most complete atlas of solar HP emission to date.

  14. Photon management structures for solar cells

    NASA Astrophysics Data System (ADS)

    Bläsi, Benedikt; Hauser, Hubert; Walk, Christian; Michl, Bernhard; Guttowski, Aron; Mellor, Alexander; Benick, Jan; Peters, Marius; Jüchter, Sabrina; Wellens, Christine; Kübler, Volker; Hermle, Martin; Wolf, Andreas J.

    2012-06-01

    Since micro- and nanostructures for photon management are of increasing importance in novel high-efficiency solar cell concepts, structuring techniques with up-scaling potential play a key role in their realization. Interference lithography and nanoimprint processes are presented as technologies for origination and replication of fine-tailored photonic structures on large areas. At first, these structure origination and replication technologies are presented in detail: With the interference pattern of two or more coherent waves, a wide variety of structures with feature sizes ranging from 100 nm to 100 μm can be generated in photoresist by interference lithography. Examples are linear gratings, crossed gratings, hexagonal structures, three dimensional photonic crystals or surface-relief diffusers. The strength of this technology is that homogeneous structures can be originated on areas of up to 1.2 x 1.2 m2. The structures in photoresist, the so-called master structures, can serve as an etching mask for a pattern transfer, as a template for infiltration with different materials or they can be replicated via electroplating and subsequent replication processes. Especially in combination with replication steps, the industrially feasible production of elaborate structures is possible. As a particularly interesting process, nanoimprint lithography (NIL) is described in detail. As a way towards industrial production, a roller NIL tool is presented. After the description of the basic technologies, three application examples for solar cells are presented with details about the design of the structures, the structuring processes, sample characterization and evaluation: (1) honeycomb structures for the front side texturization of multicrystalline silicon wafer solar cells, (2) diffractive rear side gratings for absorption enhancement in the spectral region near the band gap of silicon, and (3) plasmonic metal nanoparticle arrays manufactured by combined imprint and lift off

  15. Graphene Solar Photon Sails and Interstellar Arks

    NASA Astrophysics Data System (ADS)

    Matloff, G. L.

    2014-06-01

    A review of conceptual interstellar generation ships is followed by a presentation of optical and thermal properties of graphene and a discussion of kinematics/thermal-aspects of the solar-acceleration phase of a starship propelled by a graphene hollowbody solar-photon sail. The spacecraft departs from an initially parabolic solar orbit and the sail is oriented normal to the Sun during solar-acceleration. Perihelion is constrained to 0.1 AU because humans can tolerate ~3g for several hours without lasting effects. The 5 × 106 kg payload mass and 9.16 × 106 kg sail mass are applied as cosmic-ray shielding for the ship's 20-50 person population during the ~1,400-year cruise phase. Artificial gravity, the Coriolis Effect, closed-environment agriculture, illumination, on-board energy requirements, thermal dissipation, and hygiene/recreation are considered in a discussion of habitat design. Many concepts for mid-course trajectory correction are discussed including a new one that expels mass collected by a Cassenti toroidal ion scoop in a direction normal to the ship's trajectory. Although acceleration is affected by the unfurled sail, other options are discussed, as is the problem of protection from interstellar-dust erosion. As well as presenting the total mass budget, the conclusion reviews published variations and modifications on the generation-ship theme.

  16. Photon degradation effects in terrestrial solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.; Brandhorst, H. W.; Broder, J. D.; Hart, R. E.; Lamneck, J. H.

    1978-01-01

    A certain type of photon degradation effect has been observed experimentally in n(+)/p solar cells. It is found that this effect is caused by a recombination center, the formation of which requires the simultaneous presence of a lattice defect and a silver atom or complex of atoms. The center is electrically active in its equilibrium state; the energy level of the inactive center is located in the band gap, 0.37 eV below the conduction band. Conversion to an active recombination center can be brought about either by raising the minority carrier quasi-Fermi level to coincide with the position of the latent center level in the band gap or by the direct excitation of electrons from the valence band to the latent center level. Photon degradation can be prevented either by preventing the introduction of silver through the use of a clean diffusion system and clean initial material or by eliminating lattice damage through sufficient surface material removal prior to diffusion while at the same time restricting diffusion temperatures to 875 C or below.

  17. Enhancements in Photon Pressure Measurements Using a Solar Simulator

    NASA Technical Reports Server (NTRS)

    Gray, P. A.; Edwards, D. L.; Carruth, M. R., Jr.; Munafo, Paul (Technical Monitor)

    2001-01-01

    Initial proof of concept photon momentum measurements were reported at the AIAA Conference in Reno Nevada, January 8-11, 2001. That presentation verified that photon pressure on a simulated solar sail material can be measured under high vacuum conditions using a full spectrum solar simulator and a vacuum compatible force measurement system. Modifications to this test system were implemented to enhance the accuracy of the photon pressure measurement. This paper describes the photon pressure measurement technique and modifications to increase the measurement accuracy using a candidate sail material, aluminized Mylar.

  18. Coupling of Ag Nanoparticle with Inverse Opal Photonic Crystals as a Novel Strategy for Upconversion Emission Enhancement of NaYF4: Yb(3+), Er(3+) Nanoparticles.

    PubMed

    Shao, Bo; Yang, Zhengwen; Wang, Yida; Li, Jun; Yang, Jianzhi; Qiu, Jianbei; Song, Zhiguo

    2015-11-18

    Rare-earth-ion-doped upconversion (UC) nanoparticles have generated considerable interest because of their potential application in solar cells, biological labeling, therapeutics, and imaging. However, the applications of UC nanoparticles were still limited because of their low emission efficiency. Photonic crystals and noble metal nanoparticles are applied extensively to enhance the UC emission of rare earth ions. In the present work, a novel substrate consisting of inverse opal photonic crystals and Ag nanoparticles was prepared by the template-assisted method, which was used to enhance the UC emission of NaYF4: Yb(3+), Er(3+) nanoparticles. The red or green UC emissions of NaYF4: Yb(3+), Er(3+) nanoparticles were selectively enhanced on the inverse opal substrates because of the Bragg reflection of the photonic band gap. Additionally, the UC emission enhancement of NaYF4: Yb(3+), Er(3+) nanoparticles induced by the coupling of metal nanoparticle plasmons and photonic crystal effects was realized on the Ag nanoparticles included in the inverse opal substrate. The present results demonstrated that coupling of Ag nanoparticle with inverse opal photonic crystals provides a useful strategy to enhance UC emission of rare-earth-ion-doped nanoparticles. PMID:26496243

  19. Results from the Solar Hidden Photon Search (SHIPS)

    SciTech Connect

    Schwarz, Matthias; Knabbe, Ernst-Axel; Lindner, Axel; Redondo, Javier; Ringwald, Andreas; Schneide, Magnus; Susol, Jaroslaw; Wiedemann, Günter

    2015-08-07

    We present the results of a search for transversely polarised hidden photons (HPs) with ∼3 eV energies emitted from the Sun. These hypothetical particles, known also as paraphotons or dark sector photons, are theoretically well motivated for example by string theory inspired extensions of the Standard Model. Solar HPs of sub-eV mass can convert into photons of the same energy (photon ↔ HP oscillations are similar to neutrino flavour oscillations). At SHIPS this would take place inside a long light-tight high-vacuum tube, which tracks the Sun. The generated photons would then be focused into a low-noise photomultiplier at the far end of the tube. Our analysis of 330 h of data (and 330 h of background characterisation) reveals no signal of photons from solar hidden photon conversion. We estimate the rate of newly generated photons due to this conversion to be smaller than 25 mHz/m{sup 2} at the 95% C.L. Using this and a recent model of solar HP emission, we set stringent constraints on χ, the coupling constant between HPs and photons, as a function of the HP mass.

  20. Results from the Solar Hidden Photon Search (SHIPS)

    NASA Astrophysics Data System (ADS)

    Schwarz, Matthias; Knabbe, Ernst-Axel; Lindner, Axel; Redondo, Javier; Ringwald, Andreas; Schneide, Magnus; Susol, Jaroslaw; Wiedemann, Günter

    2015-08-01

    We present the results of a search for transversely polarised hidden photons (HPs) with ~ 3 eV energies emitted from the Sun. These hypothetical particles, known also as paraphotons or dark sector photons, are theoretically well motivated for example by string theory inspired extensions of the Standard Model. Solar HPs of sub-eV mass can convert into photons of the same energy (photon leftrightarrow HP oscillations are similar to neutrino flavour oscillations). At SHIPS this would take place inside a long light-tight high-vacuum tube, which tracks the Sun. The generated photons would then be focused into a low-noise photomultiplier at the far end of the tube. Our analysis of 330 h of data (and 330 h of background characterisation) reveals no signal of photons from solar hidden photon conversion. We estimate the rate of newly generated photons due to this conversion to be smaller than 25 mHz/m2 at the 95% C.L . Using this and a recent model of solar HP emission, we set stringent constraints on χ, the coupling constant between HPs and photons, as a function of the HP mass.

  1. Photonic bandgap guiding into a composite AgPO3-glass/silica microstructured optical fibre

    NASA Astrophysics Data System (ADS)

    Konidakis, Ioannis; Zito, Gianluigi; Pissadakis, Stavros

    2012-04-01

    Infiltration of glass matrices inside Photonic Crystals Fibres (PCFs) for achieving photonic bandgap (PBG) guidance and expand devices development capabilities has been recently demonstrated. Herein, we report the fabrication of an all-solid PBG guiding PCF by suction-assisted infiltration of molten silver-metaphosphate (AgPO3) glass into the air capillaries of a commercial solid core PCF. The relatively low viscosity of the AgPO3 glass melt permitted infiltration at ~ 700 °C inside an annealing oven apparatus by applying suction with the use of a standard mechanical vacuum pump, while its low glass transition temperature of ~ 190 °C allows structural relaxations at temperatures close to ambient and the formation of high quality glass strands inside the silica structure of the PCF. The AgPO3/silica PCF was characterized by means of its transmission spectrum that showed PBG guidance over the measurement range (350-1650nm). The effect of the AgPO3 glass photosensitivity on the guiding properties of the AgPO3/silica PCF was explored by employing a 355nm, 150 ps laser irradiation. The exposure gave rise to a photo-induced enhancement of the transmission-to-stop-band extinction ratio by ~60 dB/cm as well as bandwidth tuning. Numerical calculations of the transmission spectra of the AgPO3/silica PCF have been performed for confirming the experimental results and modelling the photo-induced variation of the two-glass fibre transmission. We believe that the fabrication of the AgPO3/silica PBG fibre constitutes a strong base for the development of new in-fibre sensing and scattering-based devices, by exploiting the high photosensitivity of silver and its specific plasmon absorption properties.

  2. Nano-photonic organic solar cell architecture for advanced light management utilizing dual photonic crystals

    NASA Astrophysics Data System (ADS)

    Peer, Akshit; Biswas, Rana

    2015-09-01

    Organic solar cells have rapidly increasing efficiencies, but typically absorb less than half of the incident solar spectrum. To increase broadband light absorption, we rigorously design experimentally realizable solar cell architectures based on dual photonic crystals. Our optimized architecture consists of a polymer microlens at the air-glass interface, coupled with a photonic-plasmonic crystal at the metal cathode. The microlens focuses light on the periodic nanostructure that generates strong light diffraction. Waveguiding modes and surface plasmon modes together enhance long wavelength absorption in P3HT-PCBM. The architecture has a period of 500 nm, with absorption and photocurrent enhancement of 49% and 58%, respectively.

  3. High-Efficiency Solar Cells Using Photonic-Bandgap Materials

    NASA Technical Reports Server (NTRS)

    Dowling, Jonathan; Lee, Hwang

    2005-01-01

    Solar photovoltaic cells would be designed to exploit photonic-bandgap (PBG) materials to enhance their energy-conversion efficiencies, according to a proposal. Whereas the energy-conversion efficiencies of currently available solar cells are typically less than 30 percent, it has been estimated that the energy-conversion efficiencies of the proposed cells could be about 50 percent or possibly even greater. The primary source of inefficiency of a currently available solar cell is the mismatch between the narrow wavelength band associated with the semiconductor energy gap (the bandgap) and the broad wavelength band of solar radiation. This mismatch results in loss of power from both (1) long-wavelength photons, defined here as photons that do not have enough energy to excite electron-hole pairs across the bandgap, and (2) short-wavelength photons, defined here as photons that excite electron- hole pairs with energies much above the bandgap. It follows that a large increase in efficiency could be obtained if a large portion of the incident solar energy could be funneled into a narrow wavelength band corresponding to the bandgap. In the proposed approach, such funneling would be effected by use of PBG materials as intermediaries between the Sun and photovoltaic cells.

  4. Enhanced performances in inverted small molecule solar cells by Ag nanoparticles.

    PubMed

    Jin, Fangming; Chu, Bei; Li, Wenlian; Su, Zisheng; Zhao, Haifeng; Lee, C S

    2014-12-15

    We demonstrate a highly efficient inverted small molecular solar cell with integration of Ag nanoparticles (NPs) into the devices. The optimized device based on thermal evaporated Ag NPs provides a power conversion efficiency (PCE) of 4.87%, which offers 33% improvement than that of the reference device without Ag NPs. Such a high efficiency is mainly attributed to the improved electrical properties by virtue of the modification of the surface of ITO with Ag NPs and the enhanced light harvesting due to localized surface plasmon resonance (LSPR). The more detail enhanced mechanism of the PCE by introduction of Ag NPs is also discussed. PMID:25607480

  5. Solar constraints on hidden photons re-visited

    SciTech Connect

    Redondo, Javier; Raffelt, Georg E-mail: raffelt@mpp.mpg.de

    2013-08-01

    We re-examine solar emission of hidden photons γ' (mass m) caused by kinetic γ–γ' mixing. We calculate the emission rate with thermal field theory methods and with a kinetic equation that includes γ–γ' ''flavor oscillations'' and γ absorption and emission by the thermal medium. In the resonant case both methods yield identical emission rates which, in the longitudinal channel, are enhanced by a factor ω{sub P}{sup 2}/m{sup 2} (plasma frequency ω{sub P}) in agreement with An, Pospelov and Pradler (2013). The Sun must not emit more energy in a ''dark channel'' than allowed by solar neutrino measurements, i.e., not more than 10% of its photon luminosity. Together with the revised emission rate, this conservative requirement implies χ < 4 × 10{sup −12}(eV/m) for the kinetic mixing parameter. This is the most restrictive stellar limit below m ∼ 3eV, whereas for larger masses the transverse channel dominates together with limits from other stars. A recent analysis of XENON10 data marginally improves the solar limit, leaving open the opportunity to detect solar hidden photons with future large-scale dark matter experiments. Detecting low-mass hidden photons with the ALPS-II photon-regeneration experiment also remains possible.

  6. Thermodynamics of photon-enhanced thermionic emission solar cells

    SciTech Connect

    Reck, Kasper; Hansen, Ole

    2014-01-13

    Photon-enhanced thermionic emission (PETE) cells in which direct photon energy as well as thermal energy can be harvested have recently been suggested as a new candidate for high efficiency solar cells. Here, we present an analytic thermodynamical model for evaluation of the efficiency of PETE solar cells including an analysis of the entropy production due to thermionic emission of general validity. The model is applied to find the maximum efficiency of a PETE cell for given cathode and anode work functions and temperatures.

  7. High-flux solar photon processes: Opportunities for applications

    SciTech Connect

    Steinfeld, J.I.; Coy, S.L.; Herzog, H.; Shorter, J.A.; Schlamp, M.; Tester, J.W.; Peters, W.A.

    1992-06-01

    The overall goal of this study was to identify new high-flux solar photon (HFSP) processes that show promise of being feasible and in the national interest. Electric power generation and hazardous waste destruction were excluded from this study at sponsor request. Our overall conclusion is that there is promise for new applications of concentrated solar photons, especially in certain aspects of materials processing and premium materials synthesis. Evaluation of the full potential of these and other possible applications, including opportunities for commercialization, requires further research and testing. 100 refs.

  8. Plasmon enhanced CdS-quantum dot sensitized solar cell using ZnO nanorods array deposited with Ag nanoparticles as photoanode

    NASA Astrophysics Data System (ADS)

    Eskandari, M.; Ahmadi, V.; Yousefi rad, M.; Kohnehpoushi, S.

    2015-04-01

    CdS-quantum dot sensitized solar cell using ZnO nanorods (ZnO NRs) array deposited with Ag nanoparticles (Ag NPs) as photoanode was fabricated. Light absorption effect of Ag NPs on improvement of the cell performance was investigated. Performance improvement of metal nanoparticles (MNPs) was controlled by the structure design and architecture. Different decorations and densities of Ag NPs were utilized on the photoanode. Results showed that using 5% Ag NPs in the photoanode results in the increased efficiency, fill factor, and circuit current density from 0.28% to 0.60%, 0.22 to 0.29, and 2.18 mA/cm2 to 3.25 mA/cm2, respectively. Also, incident photon-to-current efficiencies (IPCE) results showed that cell performance improvement is related to enhanced absorption in the photoanode, which is because of the surface plasmonic resonance and light scattering of Ag NPs in the photoanode. Measurements of electrochemical impedance spectroscopy revealed that hole transfer kinetics increases with introduction of Ag NPs into photoanode. Also, it is shown that chemical capacitance increases with introduction of Ag NPs. Such increase can be attributed to the surface palsmonic resonance of Ag NPs which leads to absorption of more light in the photoanode and generation of more photoelectron in the photoanode.

  9. Photonic crystals for improving light absorption in organic solar cells

    SciTech Connect

    Duché, D. Le Rouzo, J.; Masclaux, C.; Gourgon, C.

    2015-02-07

    We theoretically and experimentally study the structuration of organic solar cells in the shape of photonic crystal slabs. By taking advantage of the optical properties of photonic crystals slabs, we show the possibility to couple Bloch modes with very low group velocities in the active layer of the cells. These Bloch modes, also called slow Bloch modes (SBMs), allow increasing the lifetime of photons within the active layer. Finally, we present experimental demonstration performed by using nanoimprint to directly pattern the standard poly-3-hexylthiophène:[6,6]-phenyl-C61-butiryc acid methyl ester organic semiconductor blend in thin film form in the shape of a photonic crystal able to couple SBMs. In agreement with the model, optical characterizations will demonstrate significant photonic absorption gains.

  10. Occurrence of two-photon absorption saturation in Ag nanocolloids, prepared by chemical reduction method

    NASA Astrophysics Data System (ADS)

    Rahulan, K. Mani; Ganesan, S.; Aruna, P.

    2012-09-01

    Silver nanocolloids stabilized with polyvinyl pyrrolidone (PVP) have been prepared from (AgNO3) by a chemical reduction method, involving the intermediate preparation of (Ag2O) colloidal dispersions in the presence of sodium dodecycle sulfate as a surfactant and formaldehyde as reducing agent. The molecules of PVP play an important role in growth and agglomeration of silver nanocolloids. The formation of Ag nanocolloids was studied from the UV-vis absorption characteristics. An energy dispersive X-ray (EDX) spectrum and X-ray diffraction peak of the nanoparticles showed the highly crystalline nature of silver structure. The particle size was found to be 40 nm as analyzed from Field emission scanning electron microscopy (FESEM). The nonlinear optical and optical limiting properties of these nanoparticle dispersions were studied by using the Z-scan technique at 532 nm. Experimental results show that the Ag nanocolloids possess strong optical limiting effect, originated from absorption saturation followed by two-photon mechanism. The data show that Ag nanocolloids have great potential for nonlinear optical devices.

  11. High-flux solar photon processes

    SciTech Connect

    Lorents, D C; Narang, S; Huestis, D C; Mooney, J L; Mill, T; Song, H K; Ventura, S

    1992-06-01

    This study was commissioned by the National Renewable Energy Laboratory (NREL) for the purpose of identifying high-flux photoprocesses that would lead to beneficial national and commercial applications. The specific focus on high-flux photoprocesses is based on the recent development by NREL of solar concentrator technology capable of delivering record flux levels. We examined photolytic and photocatalytic chemical processes as well as photothermal processes in the search for processes where concentrated solar flux would offer a unique advantage. 37 refs.

  12. Enigmatic photon absorption in plasmas near solar interior conditions

    NASA Astrophysics Data System (ADS)

    Iglesias, Carlos A.

    2015-06-01

    Large systematic discrepancies between theoretical and experimental photon absorption of Fe plasmas applicable to the solar interior were reported [Bailey et al., Nature 517, 56 (2015)]. The disagreement is examined in the context of the Thomas-Reiche-Kuhn f-sum rule. The analysis identifies several anomalies in the experimental results.

  13. Tuning Ag29 nanocluster light emission from red to blue with one and two-photon excitation

    NASA Astrophysics Data System (ADS)

    Russier-Antoine, Isabelle; Bertorelle, Franck; Hamouda, Ramzi; Rayane, Driss; Dugourd, Philippe; Sanader, Željka; Bonačić-Koutecký, Vlasta; Brevet, Pierre-François; Antoine, Rodolphe

    2016-01-01

    We demonstrate that the tuning of the light emission from red to blue in dihydrolipoic acid (DHLA) capped Ag29 nanoclusters can be trigged with one and two photon excitations. The cluster stoichiometry was determined with mass spectrometry and found to be Ag29(DHLA)12. In a detailed optical investigation, we show that these silver nanoclusters exhibit a strong red photoluminescence visible to the naked eye and characterized by a quantum yield of nearly ~2% upon one-photon excitation. In the nonlinear optical (NLO) study of the properties of the clusters, the two-photon excited fluorescence spectra were recorded and their first hyperpolarizability obtained. The two-photon absorption cross-section at ~800 nm for Ag29(DHLA)12 is higher than 104 GM and the hyperpolarizability is 106 × 10-30 esu at the same excitation wavelength. The two-photon excited fluorescence spectrum appears strongly blue-shifted as compared to the one-photon excited spectrum, displaying a broad band between 400 and 700 nm. The density functional theory (DFT) provides insight into the structural and electronic properties of Ag29(DHLA)12 as well as into interplay between metallic subunit or core and ligands which is responsible for unique optical properties.We demonstrate that the tuning of the light emission from red to blue in dihydrolipoic acid (DHLA) capped Ag29 nanoclusters can be trigged with one and two photon excitations. The cluster stoichiometry was determined with mass spectrometry and found to be Ag29(DHLA)12. In a detailed optical investigation, we show that these silver nanoclusters exhibit a strong red photoluminescence visible to the naked eye and characterized by a quantum yield of nearly ~2% upon one-photon excitation. In the nonlinear optical (NLO) study of the properties of the clusters, the two-photon excited fluorescence spectra were recorded and their first hyperpolarizability obtained. The two-photon absorption cross-section at ~800 nm for Ag29(DHLA)12 is higher than 104

  14. Photon-enhanced thermionic emission for solar concentrator systems

    NASA Astrophysics Data System (ADS)

    Schwede, Jared W.; Bargatin, Igor; Riley, Daniel C.; Hardin, Brian E.; Rosenthal, Samuel J.; Sun, Yun; Schmitt, Felix; Pianetta, Piero; Howe, Roger T.; Shen, Zhi-Xun; Melosh, Nicholas A.

    2010-09-01

    Solar-energy conversion usually takes one of two forms: the `quantum' approach, which uses the large per-photon energy of solar radiation to excite electrons, as in photovoltaic cells, or the `thermal' approach, which uses concentrated sunlight as a thermal-energy source to indirectly produce electricity using a heat engine. Here we present a new concept for solar electricity generation, photon-enhanced thermionic emission, which combines quantum and thermal mechanisms into a single physical process. The device is based on thermionic emission of photoexcited electrons from a semiconductor cathode at high temperature. Temperature-dependent photoemission-yield measurements from GaN show strong evidence for photon-enhanced thermionic emission, and calculated efficiencies for idealized devices can exceed the theoretical limits of single-junction photovoltaic cells. The proposed solar converter would operate at temperatures exceeding 200°C, enabling its waste heat to be used to power a secondary thermal engine, boosting theoretical combined conversion efficiencies above 50%.

  15. Photon-enhanced thermionic emission for solar concentrator systems.

    PubMed

    Schwede, Jared W; Bargatin, Igor; Riley, Daniel C; Hardin, Brian E; Rosenthal, Samuel J; Sun, Yun; Schmitt, Felix; Pianetta, Piero; Howe, Roger T; Shen, Zhi-Xun; Melosh, Nicholas A

    2010-09-01

    Solar-energy conversion usually takes one of two forms: the 'quantum' approach, which uses the large per-photon energy of solar radiation to excite electrons, as in photovoltaic cells, or the 'thermal' approach, which uses concentrated sunlight as a thermal-energy source to indirectly produce electricity using a heat engine. Here we present a new concept for solar electricity generation, photon-enhanced thermionic emission, which combines quantum and thermal mechanisms into a single physical process. The device is based on thermionic emission of photoexcited electrons from a semiconductor cathode at high temperature. Temperature-dependent photoemission-yield measurements from GaN show strong evidence for photon-enhanced thermionic emission, and calculated efficiencies for idealized devices can exceed the theoretical limits of single-junction photovoltaic cells. The proposed solar converter would operate at temperatures exceeding 200 degrees C, enabling its waste heat to be used to power a secondary thermal engine, boosting theoretical combined conversion efficiencies above 50%. PMID:20676086

  16. Two-photon Photo-emission of Ultrathin Film PTCDA Morphologies on Ag(111)

    SciTech Connect

    Yang, Aram; Yang, Aram; Shipman, Steven T.; Garrett-Roe, Sean; Johns, James; Strader, Matt; Szymanski, Paul; Muller, Eric; Harris, Charles B.

    2007-11-29

    Morphology- and layer-dependent electronic structure and dynamics at the PTCDA/Ag(111) interface have been studied with angle-resolved two-photon photoemission. In Stranski-Krastanov growth modes, the exposed wetting layer inhibited the evolution of the vacuum level and valence band to bulk values. For layer-by-layer growth, we observed the transition of electron structure from monolayer to bulk values within eight monolayers. Effective masses and lifetimes of the conduction band and the n=1 image potential state were measured to be larger for disordered layers. The effective mass was interpreted in the context of charge mobility measurements.

  17. Ideal solar cell equation in the presence of photon recycling

    SciTech Connect

    Lan, Dongchen Green, Martin A.

    2014-11-07

    Previous derivations of the ideal solar cell equation based on Shockley's p-n junction diode theory implicitly assume negligible effects of photon recycling. This paper derives the equation in the presence of photon recycling that modifies the values of dark saturation and light-generated currents, using an approach applicable to arbitrary three-dimensional geometries with arbitrary doping profile and variable band gap. The work also corrects an error in previous work and proves the validity of the reciprocity theorem for charge collection in such a more general case with the previously neglected junction depletion region included.

  18. Photon Acceleration Model of Flexible Spinning Solar Sail

    NASA Astrophysics Data System (ADS)

    Mimasu, Yuya; Kitajima, Akifumi; Yamaguchi, Tomohiro; Funase, Ryu; Y. Morimoto, Mutsuko; Sawada, Hirotaka; Takeuchi, Hiroshi; Mori, Osamu; Tsuda, Yuichi; Kawaguchi, Jun'ichiro

    The solar sailing spacecraft is one of the promising propulsion systems for the future deep space exploration mission. Japan Aerospace Exploration Agency (JAXA) has been studying the spin solar sail spacecraft which has a squared-shape type solar sail. One of the most significant objective to control the satellite orbit of the spacecraft is to estimate the thrust force induced by the photon, namely to establish the acceleration model before the launch. In a view point to use this model in orbit, the calibration of the acceleration model and evaluation of the dynamics on orbit are also important issue. This paper presents the way to construct the acceleration model of the Solar Radiation Pressure (SRP) on ground, and the calibration and evaluation strategy for this model by using the on-orbit data.

  19. Tuning Ag29 nanocluster light emission from red to blue with one and two-photon excitation.

    PubMed

    Russier-Antoine, Isabelle; Bertorelle, Franck; Hamouda, Ramzi; Rayane, Driss; Dugourd, Philippe; Sanader, Željka; Bonačić-Koutecký, Vlasta; Brevet, Pierre-François; Antoine, Rodolphe

    2016-02-01

    We demonstrate that the tuning of the light emission from red to blue in dihydrolipoic acid (DHLA) capped Ag29 nanoclusters can be trigged with one and two photon excitations. The cluster stoichiometry was determined with mass spectrometry and found to be Ag29(DHLA)12. In a detailed optical investigation, we show that these silver nanoclusters exhibit a strong red photoluminescence visible to the naked eye and characterized by a quantum yield of nearly ∼2% upon one-photon excitation. In the nonlinear optical (NLO) study of the properties of the clusters, the two-photon excited fluorescence spectra were recorded and their first hyperpolarizability obtained. The two-photon absorption cross-section at ∼800 nm for Ag29(DHLA)12 is higher than 10(4) GM and the hyperpolarizability is 106 × 10(-30) esu at the same excitation wavelength. The two-photon excited fluorescence spectrum appears strongly blue-shifted as compared to the one-photon excited spectrum, displaying a broad band between 400 and 700 nm. The density functional theory (DFT) provides insight into the structural and electronic properties of Ag29(DHLA)12 as well as into interplay between metallic subunit or core and ligands which is responsible for unique optical properties. PMID:26765164

  20. The role of Ag nanoparticles in inverted polymer solar cells: Surface plasmon resonance and backscattering centers

    NASA Astrophysics Data System (ADS)

    Xu, Peng; Shen, Liang; Meng, Fanxu; Zhang, Jiaqi; Xie, Wenfa; Yu, Wenjuan; Guo, Wenbin; Jia, Xu; Ruan, Shengping

    2013-03-01

    Here, we demonstrate silver (Ag) nanoparticles (NPs) existing in molybdenum trioxide (MoO3) buffer layers can improve the photocurrent by surface plasmon resonance (SPR) and backscattering enhancement. The device structure is glass/indium tin oxides/titanium dioxide (TiO2)/regioregular poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester/MoO3/Ag NPs/MoO3/Ag. Compared to the device without Ag NPs, the short current density (Jsc) is improved from 7.76 ± 0.14 mA/cm2 to 8.89 ± 0.12 mA/cm2, and the power conversion efficiency is also enhanced from 2.70% ± 0.11% to 3.35% ± 0.08%. The transmittance spectra show that the device with Ag NPs has weaker transmittance than the device without, which could be attributed to the photons absorption of Ag NPs and light scattering by Ag NPs. The absorption profile of the devices with or without Ag NPs is simulated using finite-difference time-domain methods. It is approved that the Ag NPs result in the absorption improvement by SPR and backscattering enhancement.

  1. One-pot synthesis and transfer of PMMA/Ag photonic nanocomposites by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Karoutsos, V.; Koutselas, I.; Orfanou, P.; Mpatzaka, Th.; Vasileiadis, M.; Vassilakopoulou, A.; Vainos, N. A.; Perrone, A.

    2015-08-01

    Nanocomposite films comprising metallic nanoparticles in polymer matrices find increasing use in emerging photonic, electronic and microsystem applications owing to their tailored advanced functionalities. The versatile development of such films based on poly-methyl-methacrylate (PMMA) matrix having embedded Ag nanoparticles is addressed here. Two low-cost one-pot chemical methods for the synthesis of bulk target nanocomposite materials are demonstrated. These nanocomposites are subsequently transferred via pulsed laser deposition using 193 nm ArF excimer laser radiation, producing films maintaining the structural and functional properties. Both target- and laser-deposited materials have been thoroughly characterized using microscopic, spectroscopic and thermal analysis methods. Infrared spectra demonstrated the close molecular PMMA chain similarity for both target and film materials, though structural alterations identified by thermal analysis proved the enhanced characteristics of films grown. High-resolution electron microscopy proved the transfer of Ag nanoparticles sized 10-50 nm. Visible absorption peaked in the spectral range of 430-440 nm and attributed to the Ag nanocomposite plasmonic response verifying the transfer of the functional performance from target to film.

  2. Observational capabilities of solar satellite "Coronas-Photon"

    NASA Astrophysics Data System (ADS)

    Kotov, Yu.

    Coronas-Photon mission is the third satellite of the Russian Coronas program on solar activity observation The main goal of the Coronas-Photon is the study of solar hard electromagnetic radiation in the wide energy range from UV up to high energy gamma-radiation sim 2000MeV Scientific payload for solar radiation observation consists of three type of instruments 1 monitors Natalya-2M Konus-RF RT-2 Penguin-M BRM Phoka Sphin-X Sokol for spectral and timing measurements of full solar disk radiation with timing in flare burst mode up to one msec Instruments Natalya-2M Konus-RF RT-2 will cover the wide energy range of hard X-rays and soft Gamma rays 15keV to 2000MeV and will together constitute the largest area detectors ever used for solar observations Detectors of gamma-ray monitors are based on structured inorganic scintillators with energy resolution sim 5 for nuclear gamma-line band to 35 for GeV-band PSD analysis is used for gamma neutron separation for solar neutron registration T 30MeV Penguin-M has capability to measure linear polarization of hard X-rays using azimuth are measured by Compton scattering asymmetry in case of polarization of an incident flux For X-ray and EUV monitors the scintillation phoswich detectors gas proportional counter CZT assembly and Filter-covered Si-diodes are used 2 Telescope-spectrometer TESIS for imaging solar spectroscopy in X-rays with angular resolution up to 1 in three spectral lines and RT-2 CZT assembly of CZT

  3. Experimental search for solar hidden photons in the eV energy range using kinetic mixing with photons

    SciTech Connect

    Mizumoto, T.; Ohta, R.; Horie, T.; Suzuki, J.; Minowa, M.; Inoue, Y. E-mail: comic@icepp.s.u-tokyo.ac.jp E-mail: jsuzuki@icepp.s.u-tokyo.ac.jp E-mail: minowa@phys.s.u-tokyo.ac.jp

    2013-07-01

    We have searched for solar hidden photons in the eV energy range using a dedicated hidden photon detector. The detector consisted of a parabolic mirror with a diameter of 500 mm and a focal length of 1007 mm installed in a vacuum chamber, and a photomultiplier tube at its focal point. The detector was attached to the Tokyo axion helioscope, Sumico which has a mechanism to track the sun. From the result of the measurement, we found no evidence for the existence of hidden photons and set a limit on the photon-hidden photon mixing parameter χ depending on the hidden photon mass m{sub γ'}.

  4. Triplet-triplet annihilation photon-upconversion: towards solar energy applications.

    PubMed

    Gray, Victor; Dzebo, Damir; Abrahamsson, Maria; Albinsson, Bo; Moth-Poulsen, Kasper

    2014-06-14

    Solar power production and solar energy storage are important research areas for development of technologies that can facilitate a transition to a future society independent of fossil fuel based energy sources. Devices for direct conversion of solar photons suffer from poor efficiencies due to spectrum losses, which are caused by energy mismatch between the optical absorption of the devices and the broadband irradiation provided by the sun. In this context, photon-upconversion technologies are becoming increasingly interesting since they might offer an efficient way of converting low energy solar energy photons into higher energy photons, ideal for solar power production and solar energy storage. This perspective discusses recent progress in triplet-triplet annihilation (TTA) photon-upconversion systems and devices for solar energy applications. Furthermore, challenges with evaluation of the efficiency of TTA-photon-upconversion systems are discussed and a general approach for evaluation and comparison of existing systems is suggested. PMID:24733519

  5. Non-toxic silver iodide (AgI) quantum dots sensitized solar cells

    SciTech Connect

    Moosakhani, S.; Sabbagh Alvani, A.A.; Sarabi, A.A.; Sameie, H.; Salimi, R.; Kiani, S.; Ebrahimi, Y.

    2014-12-15

    Highlights: • We have demonstrated AgI sensitized solar cell for the first time. • Obtained mesoporous titania powders possessed small crystallite size, high purity and surface area, and developed mesopores with a narrow pore size distribution. • Photovoltaic measurements revealed the electron injection from AgI to TiO{sub 2}. • The assembled AgI-QD solar cells yielded a power conversion efficiency of 0.64% under one sun illumination. • AgI may be a suitable candidate material for use as a non-toxic sensitizer in QDSSC. - Abstract: The present study reports the performance of a new photosensitizer -AgI quantum dots (QDs)- and mesoporous titania (TiO{sub 2}) nanocrystals synthesized by sol–gel (SG) method for solar cells. Furthermore, the effects of n-heptane on the textural properties of TiO{sub 2} nanocrystals were comprehensively investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N{sub 2} adsorption–desorption measurements, and UV–vis spectroscopy. TiO{sub 2} powders exhibited an anatase-type mesoporous structure with a high surface area of 89.7 m{sup 2}/g. Afterwards, the QDs were grown on mesoporous TiO{sub 2} surface to fabricate a TiO{sub 2}/AgI electrode by a successive ionic layer adsorption and reaction (SILAR) deposition route. Current–voltage characteristics and electrochemical impedance spectroscopy (EIS) data demonstrated that the injection of photoexcited electrons from AgI QDs into the TiO{sub 2} matrix produces photocurrents. The assembled AgI-QD solar cells yielded a power conversion efficiency of 0.64% and a short-circuit current of 2.13 mA/cm{sup 2} under one sun illumination.

  6. Photocurrent enhancements of organic solar cells by altering dewetting of plasmonic Ag nanoparticles

    PubMed Central

    Fleetham, Tyler; Choi, Jea-Young; Choi, Hyung Woo; Alford, Terry; Jeong, Doo Seok; Lee, Taek Sung; Lee, Wook Seong; Lee, Kyeong-Seok; Li, Jian; Kim, Inho

    2015-01-01

    Incorporation of metal nanoparticles into active layers of organic solar cells is one of the promising light trapping approaches. The size of metal nanoparticles is one of key factors to strong light trapping, and the size of thermally evaporated metal nanoparticles can be tuned by either post heat treatment or surface modification of substrates. We deposited Ag nanoparticles on ITO by varying nominal thicknesses, and post annealing was carried out to increase their size in radius. PEDOT:PSS was employed onto the ITO substrates as a buffer layer to alter the dewetting behavior of Ag nanoparticles. The size of Ag nanoparticles on PEDOT:PSS were dramatically increased by more than three times compared to those on the ITO substrates. Organic solar cells were fabricated on the ITO and PEDOT:PSS coated ITO substrates with incorporation of those Ag nanoparticles, and their performances were compared. The photocurrents of the cells with the active layers on PEDOT:PSS with an optimal choice of the Ag nanoparticles were greatly enhanced whereas the Ag nanoparticles on the ITO substrates did not lead to the photocurrent enhancements. The origin of the photocurrent enhancements with introducing the Ag nanoparticles on PEDOT:PSS are discussed. PMID:26388104

  7. Photocurrent enhancements of organic solar cells by altering dewetting of plasmonic Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Fleetham, Tyler; Choi, Jea-Young; Choi, Hyung Woo; Alford, Terry; Jeong, Doo Seok; Lee, Taek Sung; Lee, Wook Seong; Lee, Kyeong-Seok; Li, Jian; Kim, Inho

    2015-09-01

    Incorporation of metal nanoparticles into active layers of organic solar cells is one of the promising light trapping approaches. The size of metal nanoparticles is one of key factors to strong light trapping, and the size of thermally evaporated metal nanoparticles can be tuned by either post heat treatment or surface modification of substrates. We deposited Ag nanoparticles on ITO by varying nominal thicknesses, and post annealing was carried out to increase their size in radius. PEDOT:PSS was employed onto the ITO substrates as a buffer layer to alter the dewetting behavior of Ag nanoparticles. The size of Ag nanoparticles on PEDOT:PSS were dramatically increased by more than three times compared to those on the ITO substrates. Organic solar cells were fabricated on the ITO and PEDOT:PSS coated ITO substrates with incorporation of those Ag nanoparticles, and their performances were compared. The photocurrents of the cells with the active layers on PEDOT:PSS with an optimal choice of the Ag nanoparticles were greatly enhanced whereas the Ag nanoparticles on the ITO substrates did not lead to the photocurrent enhancements. The origin of the photocurrent enhancements with introducing the Ag nanoparticles on PEDOT:PSS are discussed.

  8. Light trapping in thin film solar cells using textured photonic crystal

    DOEpatents

    Yi, Yasha; Kimerling, Lionel C.; Duan, Xiaoman; Zeng, Lirong

    2009-01-27

    A solar cell includes a photoactive region that receives light. A photonic crystal is coupled to the photoactive region, wherein the photonic crystal comprises a distributed Bragg reflector (DBR) for trapping the light.

  9. Photon-degradation effects in terrestrial silicon solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.; Brandhorst, H. W.; Broder, J. D.; Hart, R. E.; Lamneck, J. H.

    1979-01-01

    The effect of instability in terrestrial solar cells and identification of mechanisms involved are presented. The effect is similar to photon-induced degradation in radiation-damaged space solar cells, with reduction in cell output in n(+)/p cells upon exposure to illumination or upon the application of a sufficiently high forward bias. It was found that the photon-degradation effect is caused by a recombination center identified as a complex of a lattice defect and a silver atom or cluster of atoms. The center is electrically inactive in its ground state but can be activated by raising the minority-carrier quasi-Fermi level to coincide with the position of the latent-center level in the band gap, or by direct excitation of electrons from the valence band to the latent-center level. Photon degradation can be prevented by avoiding the introduction of silver through the use of a clean diffusion system and clean initial material, or by eliminating lattice damage by sufficient surface material removal prior to diffusion and restricting diffusion temperatures to 875 C or below.

  10. World Ships: The Solar-Photon Sail Option

    NASA Astrophysics Data System (ADS)

    Matloff, G. L.

    The World Ship, a spacecraft large enough to simulate a small-scale terrestrial internal environment, may be the best feasible option to transfer members of a technological civilization between neighboring stars. Because of the projected size of these spacecraft, journey durations of ~1,000 years seem likely. One of the propulsion options for World Ships is the hyper-thin, likely space-manufactured solar-photon sail, unfurled as close to the migrating civilization's home star as possible. Because the sail and associated structure can be wound around the habitat while not in use, it represents the only known ultimately feasible interstellar propulsion system that can be applied for en route galactic-cosmic ray shielding as well as acceleration/ deceleration. This paper reviews the three suggested sail configurations that can be applied to world ship propulsion: parachute, hollow-body and hoop sails. Possible existing and advanced sail and structure materials and the predicted effects on the sail of the near-Sun space environment are reviewed. Consideration of solar-photon-sail World Ships also affects SETI (the Search for Extraterrestrial Intelligence). Can we detect such craft in flight? When in a star's lifetime is migration using such craft likely? What classes of stars are good candidates for solar-sail World-Ship searches?

  11. Ohmic contact effect of Ag-nanodots on quantum efficiency of Si solar cell.

    PubMed

    Choi, Jaeho; Parida, Bhaskar; Ji, Hyung Yong; Park, Seungil; Kim, Keunjoo

    2012-07-01

    The authors investigated Si solar cell with the inclusion of nano-Ag dots using the ink-jet printer. These nano-Ag dots were used for the Ohmic contact layer on phospho-silicate glass layer, which was not removed after the formation of Si emitter layer by phosphorus diffusion process. The SiNx layer deposited on the nano-Ag dots shows the catalyst selective growth and so the layer formed beneath of nano-Ag dots. The photoreflectances show that the long wavelength from 360 nm to 1200 nm tends to be increased as the density of the nano-Ag is increased. In case of short wavelength from 294 nm to 367 nm, it shows the opposite trend, indicating the plasmon effect of the nano-Ag. As embedding the nano-Ag dots on the phospho-silicate glass layer, the blocked Ohmic contact was opened and the quantum efficiency of 14.4% was achieved, which is higher than the reference sample of 12.72% without the glass layer. The nano-Ag dots form the good Ohmic contact and also enhance the light conversion efficiency with the formation of surface plasmon. PMID:22966609

  12. Synthesis and properties of polyamide-Ag2S composite based solar energy absorber surfaces

    NASA Astrophysics Data System (ADS)

    Krylova, Valentina; Baltrusaitis, Jonas

    2013-10-01

    Silver sulfide (Ag2S), an efficient solar light absorber, was synthesized using a modified chemical bath deposition (CBD) method and polyamide 6 (PA) as a host material via solution phase reaction between AgNO3 and Na2S2O3. X-ray diffraction (XRD) data showed a single, α-Ag2S (acanthite), crystalline phase present while surface and bulk chemical analyses, performed using X-ray photoelectron (XPS) and energy dispersive (EDS) spectroscopies, showed 2:1 Ag:S ratio. Direct and indirect bandgaps obtained from Tauc plots were 1.3 and 2.3 eV, respectively. Detailed surface chemical analysis showed the presence of three distinct sulfur species with majority component due to the Ag2S chemical bonds and minority components due to two types of oxygen-sulfur bonds. Conductivity of the resulting composite material was shown to change with the reaction time thus enabling to obtain controlled conductivity composite material. The synthesis method presented is based on the low solubility of Ag2S and is potentially green, no by-product producing, as all Ag2S nucleated outside the host material can be recycled into the process via dissolving it in HNO3.

  13. TCO/Ag/TCO transparent electrodes for solar cells application

    NASA Astrophysics Data System (ADS)

    Boscarino, S.; Crupi, I.; Mirabella, S.; Simone, F.; Terrasi, A.

    2014-09-01

    Among transparent electrodes, transparent conductive oxides (TCO)/metal/TCO structures can achieve optical and electrical performances comparable to, or better than, single TCO layers and very thin metallic films. In this work, we report on thin multilayers based on aluminum zinc oxide (AZO), indium tin oxide (ITO) and Ag deposited by RF magnetron sputtering on soda lime glass at room temperature. The TCO/Ag/TCO structures with thicknesses of about 50/10/50 nm were deposited with all combinations of AZO and ITO as top and bottom layers. While the electrical conductivity is dominated by the Ag intralayer irrespective of the TCO nature, the optical transmissions show a dependence on the nature of the top and bottom TCOs, mainly due to the change in the reflectivity of the multilayers. Structural, electrical and optical properties are studied to optimize the structure for very thin transparent electrodes suitable for photovoltaic applications.

  14. Two-photon absorption of ligand-protected Ag15 nanoclusters. Towards a new class of nonlinear optics nanomaterials.

    PubMed

    Sanader, Željka; Krstić, Marjan; Russier-Antoine, Isabelle; Bertorelle, Franck; Dugourd, Philippe; Brevet, Pierre-François; Antoine, Rodolphe; Bonačić-Koutecký, Vlasta

    2016-05-14

    We report theoretical and experimental results on two-photon absorption (TPA) cross section of thiolated small silver cluster Ag15L11 exhibiting extraordinary large TPA in red. Our findings provide the responsible mechanism and allow proposing new classes of nanoclusters with large TPAs which are promising for biological and medical applications. PMID:26821589

  15. Giant enhancement of Kerr rotation in two-dimensional Bismuth iron garnet/Ag photonic crystals

    NASA Astrophysics Data System (ADS)

    Liang, Hong; Liu, Huan; Zhang, Qiang; Fu, Shu-Fang; Zhou, Sheng; Wang, Xuan-Zhang

    2015-06-01

    Kerr effects of two-dimensional (2D) Bismuth iron garnet (BIG)/Ag photonic crystals (PCs) combined magnetic and plasmonic functionalities is investigated with the effective medium theory. An analytical expression of Kerr rotation angles is derived, in which the effects of the surface pasmons polaritons (SPP) on magneto-optical (MO) activities are reflected. The largest enhancement of Kerr rotation up to now is demonstrated, which is improved three orders of magnitude compared with that of BIG film. When λ < 750 nm all of the reflection are over 10% for the arbitrary filling ratio f1, in addition, the enhancement of Kerr rotation angles are at least one order of magnitude. Project supported by the National Natural Science Foundation of China (Grant Nos. 11104050, 10947168, 11204056, and 11304068).

  16. Photon recycling in lead iodide perovskite solar cells.

    PubMed

    Pazos-Outón, Luis M; Szumilo, Monika; Lamboll, Robin; Richter, Johannes M; Crespo-Quesada, Micaela; Abdi-Jalebi, Mojtaba; Beeson, Harry J; Vrućinić, Milan; Alsari, Mejd; Snaith, Henry J; Ehrler, Bruno; Friend, Richard H; Deschler, Felix

    2016-03-25

    Lead-halide perovskites have emerged as high-performance photovoltaic materials. We mapped the propagation of photogenerated luminescence and charges from a local photoexcitation spot in thin films of lead tri-iodide perovskites. We observed light emission at distances of ≥50 micrometers and found that the peak of the internal photon spectrum red-shifts from 765 to ≥800 nanometers. We used a lateral-contact solar cell with selective electron- and hole-collecting contacts and observed that charge extraction for photoexcitation >50 micrometers away from the contacts arose from repeated recycling between photons and electron-hole pairs. Thus, energy transport is not limited by diffusive charge transport but can occur over long distances through multiple absorption-diffusion-emission events. This process creates high excitation densities within the perovskite layer and allows high open-circuit voltages. PMID:27013728

  17. Photon recycling in lead iodide perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Pazos-Outón, Luis M.; Szumilo, Monika; Lamboll, Robin; Richter, Johannes M.; Crespo-Quesada, Micaela; Abdi-Jalebi, Mojtaba; Beeson, Harry J.; Vrućinić, Milan; Alsari, Mejd; Snaith, Henry J.; Ehrler, Bruno; Friend, Richard H.; Deschler, Felix

    2016-03-01

    Lead-halide perovskites have emerged as high-performance photovoltaic materials. We mapped the propagation of photogenerated luminescence and charges from a local photoexcitation spot in thin films of lead tri-iodide perovskites. We observed light emission at distances of ≥50 micrometers and found that the peak of the internal photon spectrum red-shifts from 765 to ≥800 nanometers. We used a lateral-contact solar cell with selective electron- and hole-collecting contacts and observed that charge extraction for photoexcitation >50 micrometers away from the contacts arose from repeated recycling between photons and electron-hole pairs. Thus, energy transport is not limited by diffusive charge transport but can occur over long distances through multiple absorption-diffusion-emission events. This process creates high excitation densities within the perovskite layer and allows high open-circuit voltages.

  18. Photon Enhanced Thermionic Emission for Solar Concentrator Systems

    NASA Astrophysics Data System (ADS)

    Schwede, Jared; Bargatin, Igor; Riley, Dan; Hardin, Brian; Howe, Roger; Melosh, Nick; Shen, Zhi-Xun

    2010-03-01

    Photon Enhanced Thermionic Emission (PETE) is a newly proposed method of solar energy harvesting which combines quantum and thermal processes into a single electricity generating mechanism. The proposed PETE device can be thought of as a synthesis of a photovoltaic (PV) cell and thermionic converter, and the process is expected to overcome some of the challenges which limit either of its intellectual antecedents. Because PETE can harvest the energy of sub-bandgap photons and recover heat produced by thermalization and recombination, possible PETE conversion efficiencies exceed the theoretical limits of single junction PV cells. A PETE converter operates most efficiently at high temperatures, which would allow the waste heat of the device to be used to power a secondary thermal cycle. Principles of PETE operation and limiting efficiencies are described.

  19. Radiative recombination and photon recycling in gallium arsenide solar cells

    NASA Astrophysics Data System (ADS)

    Lundstrom, M. S.; Melloch, M. R.; Lush, G. B.; Patkar, M. P.; Young, M.; Durbin, S. M.; Gray, J. L.; MacMillan, H. F.; Keyes, B. M.; Levi, D. H.; Ahrenkiel, R. K.

    1992-12-01

    This talk reviews experimental work to develop a detailed understanding of radiative recombination in n-GaAs. Photoluminescence decay studies of minority carrier lifetimes versus doping in n-GaAs are presented. We show that when the substrate is removed by etching, photon recycling is enhanced, and lifetimes increase by nearly a factor of 10. The doping-dependent absorption coefficient is measured, and detailed balance arguments are used to relate absorption and recombination. Modeling surfaces, verified by comparison with experiments, are used to examine the effects of recycling in conventional solar cells and to explore new design options.

  20. Ag Nanodots Emitters Embedded in a Nanocrystalline Thin Film Deposited on Crystalline Si Solar Cells.

    PubMed

    Park, Seungil; Ryu, Sel Gi; Ji, HyungYong; Kim, Myeong Jun; Peck, Jong Hyeon; Kim, Keunjoo

    2016-06-01

    We fabricated crystalline Si solar cells with the inclusion of various Ag nanodots into the additional emitters of nanocrystallite Si thin films. The fabricated process was carried out on the emitter surface of p-n junction for the textured p-type wafer. The Ag thin films were deposited on emitter surfaces and annealed at various temperatures. The amorphous Si layers were also deposited on the Ag annealed surfaces by hot-wire chemical vapor deposition and then the deposited layers were doped by the second n-type doping process to form an additional emitter. From the characterization, both the Ag nanodots and the deposited amorphous Si thin films strongly reduce photo-reflectances in a spectral region between 200-400 nm. After embedding Ag nanodots in nanocrystallite Si thin films, a conversion efficiency of the sample with added emitter was achieved to 15.1%, which is higher than the 14.1% of the reference sample and the 14.7% of the de-posited sample with a-Si:H thin film after the Ag annealing process. The additional nanocrystallite emitter on crystalline Si with Ag nanodots enhances cell properties. PMID:27427665

  1. Solar energy conversion with photon-enhanced thermionic emission

    NASA Astrophysics Data System (ADS)

    Kribus, Abraham; Segev, Gideon

    2016-07-01

    Photon-enhanced thermionic emission (PETE) converts sunlight to electricity with the combined photonic and thermal excitation of charge carriers in a semiconductor, leading to electron emission over a vacuum gap. Theoretical analyses predict conversion efficiency that can match, or even exceed, the efficiency of traditional solar thermal and photovoltaic converters. Several materials have been examined as candidates for radiation absorbers and electron emitters, with no conclusion yet on the best set of materials to achieve high efficiency. Analyses have shown the complexity of the energy conversion and transport processes, and the significance of several loss mechanisms, requiring careful control of material properties and optimization of the device structure. Here we survey current research on PETE modeling, materials, and device configurations, outline the advances made, and stress the open issues and future research needed. Based on the substantial progress already made in this young topic, and the potential of high conversion efficiency based on theoretical performance limits, continued research in this direction is very promising and may yield a competitive technology for solar electricity generation.

  2. Nano-photonic Light Trapping In Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Callahan, Dennis M., Jr.

    Over the last several decades there have been significant advances in the study and understanding of light behavior in nanoscale geometries. Entire fields such as those based on photonic crystals, plasmonics and metamaterials have been developed, accelerating the growth of knowledge related to nanoscale light manipulation. Coupled with recent interest in cheap, reliable renewable energy, a new field has blossomed, that of nanophotonic solar cells. In this thesis, we examine important properties of thin-film solar cells from a nanophotonics perspective. We identify key differences between nanophotonic devices and traditional, thick solar cells. We propose a new way of understanding and describing limits to light trapping and show that certain nanophotonic solar cell designs can have light trapping limits above the so called ray-optic or ergodic limit. We propose that a necessary requisite to exceed the traditional light trapping limit is that the active region of the solar cell must possess a local density of optical states (LDOS) higher than that of the corresponding, bulk material. Additionally, we show that in addition to having an increased density of states, the absorber must have an appropriate incoupling mechanism to transfer light from free space into the optical modes of the device. We outline a portfolio of new solar cell designs that have potential to exceed the traditional light trapping limit and numerically validate our predictions for select cases. We emphasize the importance of thinking about light trapping in terms of maximizing the optical modes of the device and efficiently coupling light into them from free space. To further explore these two concepts, we optimize patterns of superlattices of air holes in thin slabs of Si and show that by adding a roughened incoupling layer the total absorbed current can be increased synergistically. We suggest that the addition of a random scattering surface to a periodic patterning can increase incoupling by

  3. High-Resolution Solar Imaging With Photon Sieves

    NASA Astrophysics Data System (ADS)

    Oktem, F. S.; Kamalabadi, F.; Davila, J. M.

    2014-12-01

    A photon sieve is a modification of a Fresnel zone plate in which open zones are replaced by a large number of circular holes. This lightweight optical device offers a superior image forming capability compared with the Fresnel zone plate, and is specially suited to observations at UV and x-ray wavelengths where refractive lenses are not available due to strong absorption of materials, and reflective mirrors are difficult to manufacture to achieve near diffraction-limited resolution. At these shorter wavelengths, photon sieves enable diffraction-limited imaging performance with relaxed manufacturing tolerances, and simple and low-cost fabrication. In this work, we present a new photon sieve imaging modality that, unlike previous designs, takes advantage of chromatic aberration. The fact that different wavelengths are focused at different distances from photon sieve is exploited to develop a novel multi-spectral imaging technique. The idea is to use a photon sieve imaging system with a moving detector which records images at different planes. Each measurement consists of superimposed images of different wavelengths, with each individual image being either in focus or out of focus. For spatially incoherent illumination, we study the problem of recovering the individual images from these superimposed measurements. We first formulate the discrete forward problem using the closed-form Fresnel imaging formulas. The inverse problem is then a multi-frame deconvolution problem involving multiple objects, and is formulated as a maximum posterior estimation problem. The resulting nonlinear optimization problem is solved using a fixed-point iterative algorithm. In contrast to traditional spectral imagers employing a series of wavelength filters, the proposed technique relies on a simple optical system, but incorporates powerful image processing methods to form spectral images computationally. In addition to diffraction-limited high spatial resolution enabled by photon sieves

  4. ZnO/Ag sputtering deposition on a-Si solar cells

    SciTech Connect

    Hayashi, Katsuhiko; Kondo, Masataka; Ishikawa, Atsuo; Yamagishi, Hideo

    1994-12-31

    In order to produce large area amorphous silicon solar cell modules and to simplify the module production process, a continuous ZnO/Ag sputtering deposition process has been applied. The authors found that by means of a continuous ZnO/Ag sputtering deposition method an adhesive a-Si/electrode contact can be realized. They compared short circuit currents of Al,ZnO/Al and ZnO/Ag back side contact cells and confirmed short circuit current increase by application of ZnO/Ag back side contact. They found that the series resistance is severely dependent on the conditions during the first stage of ZnO deposition. They confirmed the reliability of ZnO/Ag structure as the back side contact through high temperature high humidity test. After 310 hours accelerated light induced degradation test which corresponds to one year light exposure the 100cm2 integrated a-Si tandem solar cell kept the efficiency higher than 8.5%.

  5. Optimal design of one-dimensional photonic crystal back reflectors for thin-film silicon solar cells

    SciTech Connect

    Chen, Peizhuan; Hou, Guofu Zhang, Jianjun Zhang, Xiaodan; Zhao, Ying

    2014-08-14

    For thin-film silicon solar cells (TFSC), a one-dimensional photonic crystal (1D PC) is a good back reflector (BR) because it increases the total internal reflection at the back surface. We used the plane-wave expansion method and the finite difference time domain (FDTD) algorithm to simulate and analyze the photonic bandgap (PBG), the reflection and the absorption properties of a 1D PC and to further explore the optimal 1D PC design for use in hydrogenated amorphous silicon (a-Si:H) solar cells. With identified refractive index contrast and period thickness, we found that the PBG and the reflection of a 1D PC are strongly influenced by the contrast in bilayer thickness. Additionally, light coupled to the top three periods of the 1D PC and was absorbed if one of the bilayers was absorptive. By decreasing the thickness contrast of the absorptive layer relative to the non-absorptive layer, an average reflectivity of 96.7% was achieved for a 1D PC alternatively stacked with a-Si:H and SiO{sub 2} in five periods. This reflectivity was superior to a distributed Bragg reflector (DBR) structure with 93.5% and an Ag film with 93.4%. n-i-p a-Si:H solar cells with an optimal 1D PC-based BR offer a higher short-circuit current density than those with a DBR-based BR or an AZO/Ag-based BR. These results provide new design rules for photonic structures in TFSC.

  6. Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures.

    PubMed

    Park, Jung Tae; Chi, Won Seok; Jeon, Harim; Kim, Jong Hak

    2014-03-01

    TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (η) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of η is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements. PMID:24457831

  7. Two-photon Photoemission of Organic Semiconductor Molecules on Ag(111)

    SciTech Connect

    Yang, Aram

    2008-05-01

    Angle- and time-resolved two-photon photoemission (2PPE) was used to study systems of organic semiconductors on Ag(111). The 2PPE studies focused on electronic behavior specific to interfaces and ultrathin films. Electron time dynamics and band dispersions were characterized for ultrathin films of a prototypical n-type planar aromatic hydrocarbon, PTCDA, and representatives from a family of p-type oligothiophenes.In PTCDA, electronic behavior was correlated with film morphology and growth modes. Within a fewmonolayers of the interface, image potential states and a LUMO+1 state were detected. The degree to which the LUMO+1 state exhibited a band mass less than a free electron mass depended on the crystallinity of the layer. Similarly, image potential states were measured to have free electron-like effective masses on ordered surfaces, and the effective masses increased with disorder within the thin film. Electron lifetimes were correlated with film growth modes, such that the lifetimes of electrons excited into systems created by layer-by-layer, amorphous film growth increased by orders of magnitude by only a few monolayers from the surface. Conversely, the decay dynamics of electrons in Stranski-Krastanov systems were limited by interaction with the exposed wetting layer, which limited the barrier to decay back into the metal.Oligothiophenes including monothiophene, quaterthiophene, and sexithiophene were deposited on Ag(111), and their electronic energy levels and effective masses were studied as a function of oligothiophene length. The energy gap between HOMO and LUMO decreased with increasing chain length, but effective mass was found to depend on domains from high- or low-temperature growth conditions rather than chain length. In addition, the geometry of the molecule on the surface, e.g., tilted or planar, substantially affected the electronic structure.

  8. The solar photon thruster as a terrestrial pole sitter.

    PubMed

    Matloff, Gregory L

    2004-05-01

    Geosynchronous satellites are invisible at high latitudes. A pole-sitting spacecraft would have communication, climate-studies, and near-polar Earth observation applications. We present a pole-sitter based on the solar photon thruster (SPT), a two-sail variant of the solar sail using a large curved collector sail (always normal to the Sun) to direct sunlight against a much smaller thruster. Thrust decreases slower for an SPT than for a conventional sail arrangement as the angle between sunlight and the collector normal increases. An SPT pole-sitter is offset from the terrestrial pole so that a component of Earth gravity balances the solar radiation-pressure component pushing the SPT off station. The component of gravitational attraction of the Earth pulling the spacecraft towards Earth is also balanced by a solar radiation-pressure component. Results are presented for 80-100% collector/thruster reflectivities. For a spacecraft areal mass thickness of 0.002 kg/m(2), collector and thruster reflectivities of 0.9, the SPT can be situated above latitude 45 degrees at a distance of approximately 60 Earth radii. An SPT pole sitter would be affected by lunar perturbation, which can be compensated for by an on-board rocket thruster producing 2 x 10(-6) g acceleration, a second SPT thruster sail thrusting against the influence of the Moon, or by directing a microwave beam against the spacecraft. Since an SPT pole sitter is in a position rather than an orbit, the effect of terrestrial gravitation limits the size and design of the payload package, which limits terrestrial target resolution. PMID:15220163

  9. Random lasing in Eu3+ doped borate glass-ceramic embedded with Ag nanoparticles under direct three-photon excitation

    NASA Astrophysics Data System (ADS)

    Xu, Xuhui; Zhang, Wenfei; Jin, Limin; Qiu, Jianbei; Yu, Siu Fung

    2015-10-01

    We report the observation of random lasing from Eu3+ doped borate glass ceramic films embedded with Ag nanoparticles through three-photon absorption at room temperature. Under 1179 nm ultrashort femtosecond pulse excitation, discrete sharp peaks with linewidth ~0.4 nm emerge randomly from a broad emission band with peak wavelength at ~612 nm. In addition, the number of sharp peaks increases with the increase of excitation power. We also show that the emission spectrum varies with different observation angles and the corresponding lasing threshold is dependent on the excitation area. Hence, we verify unambiguously that the Eu3+ doped borate glass ceramic film supports random lasing action via three-photon absorption excitation. In addition, Ag nanoparticles, which act as light scatterers, allow the formation of random microcavities inside the bulk film.

  10. Photonic crystals with SiO2-Ag ``post-cap'' nanostructure coatings for surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kim, Seok-min; Zhang, Wei; Cunningham, Brian T.

    2008-10-01

    We demonstrate that the resonant near fields of a large-area replica molded photonic crystal (PC) slab can efficiently couple light from a laser to SiO2-Ag "post-cap" nanostructures deposited on the PC surface by a glancing angle evaporation technique for achieving high surface enhanced Raman spectroscopy (SERS) enhancement factor. To examine the feasibility of the PC-SERS substrate, the simulated electric field around individual Ag particles and the measured Raman spectrum of trans-1,2-bis(4pyridyl)ethane on the PC-SERS substrate were compared with those from an ordinary glass substrate coated with the same SiO2-Ag nanostructures.

  11. Ag contact properties according to the front grid width and firing temperature for silicon solar cells.

    PubMed

    Kim, Seongtak; Park, Sungeun; Kim, Young Do; Bae, Soohyun; Boo, Hyunpil; Kim, Hyunho; Lee, Kyung Dong; Tark, Sung Ju; Kim, Donghwan

    2014-10-01

    The effect of peak firing temperature and grid width on the contact properties between Ag metal and silicon (n+ emitter) was investigated for screen-printed silicon solar cells. We confirmed the factors that control the specific contact resistance as follows: (1) the Ag coverage fraction on the silicon surface, d(2) the thickness of the glass layer and (3) the etching depth on the n+ emitter region. The lowest specific contact resistance (8.27 mΩ x cm2) was obtained at the optimum firing temperature (720 degrees C). We also found that the grid width affected the contact quality of Ag paste because the contact width related to the absorbed heat of samples in RTP system. For this reason, when the grid width was further reduced, meaning more heat absorption, more Ag crystallites grew and the glass layer thickened. Light I-V results of a 6-inch silicon solar cell with minimum busbar width were similar to the PC1D simulation results. The efficiency was improved by 0.2% with the reduction of the busbar width. PMID:25942864

  12. Optimization of photonics for corrugated thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Deparis, Olivier; Vigneron, Jean Pol; Agustsson, Otto; Decroupet, Daniel

    2009-11-01

    The amount of solar energy reaching the active (photovoltaic) layer in a thin-film solar cell can be increased by reducing the Fresnel reflection losses at the interfaces. By using corrugated interfaces (at the wavelength scale), adiabatic propagation of the electromagnetic radiation is achieved over a broad wavelength range throughout the structure, which leads to an increase in the light that is absorbed in the active layer and, ultimately, to the improvement of the photovoltaic conversion efficiency. In this article, we have considered the case of corrugated thin-film solar cell structures and we have studied theoretically the optimization of such structures from the point of view of photonics. The focus was put on periodic pyramidal interface corrugations because they were similar to those existing at the surface of corrugated transparent electrodes on which active layers can be deposited. Because of their technological importance, we chose to work with fluorine-doped tin oxide as front electrode material and with amorphous silicon as active material. Using an original three dimensional transfer matrix method, we solved the electromagnetic wave propagation problem in the general case of laterally periodic stratified media and we compared this solution with effective medium approximated solution. On the basis of typical pyramid sizes, we demonstrated, through numerical simulations, the optimization of the global light energy intake by means of corrugations of increasing complexity. The best structures were found to be based on pyramid arrays having subwavelength periods and aspect ratio values close to one. Typically, a pyramidal structure with base and height both equal to 300 nm led to a global energy intake equal to I =0.98 (integrated over the spectral range 400-710 nm), which represented a 24% improvement in comparison with the global energy intake of a planar structure (I =0.79).

  13. Direct laser patterning of transparent ITO-Ag-ITO multilayer anodes for organic solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Hyo-Joong; Seo, Ki-Won; Kim, Yong Hyeon; Choi, Jiyeon; Kim, Han-Ki

    2015-02-01

    Direct laser patterning of transparent ITO-Ag-ITO (IAI) multilayer anodes is investigated using a femtosecond fiber laser for application in organic solar cells (OSC) fabrication. By adjusting laser fluence and scan speed, we successfully patterned the IAI multilayer anode without changing the electrical or optical properties. At an optimized laser fluence of 0.6 J/cm2 and a scan speed of 200 mm/s, the patterned IAI multilayer was electrically isolated with a clean edge. The metallic Ag interlayer of the IAI multilayer plays an important role in direct laser patterning because it absorbed the laser and increases the maximum temperature in the IAI multilayer. In addition, the Ag layer could effectively decrease the temperature of the IAI multilayer after irradiation of laser. The OSC fabricated on the laser patterned IAI multilayer showed power conversion efficiencies of 3.12% (Ag 8 nm) and 2.85% (Ag 12 nm). Successful operation of the OSC indicates that direct laser patterning of IAI multilayer anodes is a promising, simple patterning technology for fabrication of IAI-based OSCs.

  14. Incorporating photon recycling into the analytical drift-diffusion model of high efficiency solar cells

    SciTech Connect

    Lumb, Matthew P.; Steiner, Myles A.; Geisz, John F.; Walters, Robert J.

    2014-11-21

    The analytical drift-diffusion formalism is able to accurately simulate a wide range of solar cell architectures and was recently extended to include those with back surface reflectors. However, as solar cells approach the limits of material quality, photon recycling effects become increasingly important in predicting the behavior of these cells. In particular, the minority carrier diffusion length is significantly affected by the photon recycling, with consequences for the solar cell performance. In this paper, we outline an approach to account for photon recycling in the analytical Hovel model and compare analytical model predictions to GaAs-based experimental devices operating close to the fundamental efficiency limit.

  15. Microwave assisted hydrothermal synthesis of Ag/AgCl/WO{sub 3} photocatalyst and its photocatalytic activity under simulated solar light

    SciTech Connect

    Adhikari, Rajesh; Gyawali, Gobinda; Sekino, Tohru; Wohn Lee, Soo

    2013-01-15

    Simulated solar light responsive Ag/AgCl/WO{sub 3} composite photocatalyst was synthesized by microwave assisted hydrothermal process. The synthesized powders were characterized by X-Ray Diffraction (XRD) spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (UV-Vis DRS), and BET surface area analyzer to investigate the crystal structure, morphology, chemical composition, optical properties and surface area of the composite photocatalyst. This photocatalyst exhibited higher photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation. Dye degradation efficiency of composite photocatalyst was found to be increased significantly as compared to that of the commercial WO{sub 3} nanopowder. Increase in photocatalytic activity of the photocatalyst was explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the composite photocatalyst. Highlights: Black-Right-Pointing-Pointer Successful synthesis of Ag/AgCl/WO{sub 3} nanocomposite. Black-Right-Pointing-Pointer Photocatalytic experiment was performed under simulated solar light. Black-Right-Pointing-Pointer Nanocomposite photocatalyst was very active as compared to WO{sub 3} commercial powder. Black-Right-Pointing-Pointer SPR effect due to Ag nanoparticles enhanced the photocatalytic activity.

  16. Sonosynthesis of an Ag/AgBr/Graphene-oxide nanocomposite as a solar photocatalyst for efficient degradation of methyl orange.

    PubMed

    Esmaeili, A; Entezari, M H

    2016-03-15

    In this study, a new method has developed for the synthesis of Ag/AgBr/Graphene-oxide (Ag/AgBr/GO) nanocomposite with high adsorption capacity and high photocatalytic activity in degradation of methyl orange (MO). In this method, ultrasound was applied in the synthesis and it was facilitated the process. The samples prepared under ultrasound were shown as Ag/AgBr/GO-U, and the samples under conventional method as Ag/AgBr/GO-C. The results of FT-IR, XRD, Raman, DRS and SEM confirmed the structure of the nanocomposites very well. Ultrasound played a key role in the formation of nanocomposite with smaller size of GO sheets and particles. Different amount of GO was used in the nanocomposite composition and their photocatalytic activities were compared. The MO in solution was completely degraded in 15 min, 30 min, and 45 min with Ag/AgBr/GO-U-1 that contained 1 mg mL(-1) GO, Ag/AgBr/GO-U-0.5 that contained 0.5 mg mL(-1) GO and Ag/AgBr/GO-C-0.5 that contained 0.5 mg mL(-1) GO, respectively. The chemical oxygen demand (COD) measurements displayed a complete mineralization in 30 min for Ag/AgBr/GO-U-0.5. The data obtained from the degradation experiments were fitted to the first-order kinetics and the adsorption obeyed the Langmuir model. The nanocatalyst did not exhibit significant loss of activity even after four cycles of successive uses. To determine the mechanism of photocatalytic degradation of MO, different scavengers were used. Based on the results, the superoxide radical, hydroxyl radical and hole had a key role in the degradation process. The Ag/AgBr/GO-U-1 nanocomposite exhibited the highest photocatalytic activity due to its high adsorption capacity and enhanced charge transfer. PMID:26724706

  17. ARPES study of the surface states from Au/Ag( 1 1 1 ): evolution with coverage and photon energy

    NASA Astrophysics Data System (ADS)

    Palomares, F. J.; Serrano, M.; Ruiz, A.; Soria, F.; Horn, K.; Alonso, M.

    2002-07-01

    The Shockley surface states formed on the (1 1 1) surfaces of noble metals have been extensively studied, but few reports exist on layered thin film systems. We present angle-resolved photoemission (ARPES) results, recorded at normal emission in the photon energy range from 21 to 49 eV, which describe the behavior of these sp-derived surface states for Au layers epitaxially grown on Ag(1 1 1). Growth was performed at room and low temperatures. In both cases, the ARPES spectra are found to evolve from Ag(1 1 1)-like to Au(1 1 1)-like features as the thickness of the Au film increases. In particular, the surface-state binding energy shifts from the Ag(1 1 1) to the bulk Au(1 1 1) position, the shift being already evident at coverages lower than one monolayer. The origin of the changes observed in the surface-state peak as a function of Au coverage and photon energy will be discussed.

  18. Photonic crystal enhanced light-trapping in thin film solar cells

    SciTech Connect

    Zhou, D.; Biswas, R.

    2008-03-01

    We utilize photonic crystals to simulate enhanced light-trapping in a-Si:H thin film solar cells. A one dimensional photonic crystal or distributed Bragg reflector with alternating dielectric layers acts as low loss backreflector. A two dimensional photonic crystal between the absorber layer and the Bragg reflector diffracts light at oblique angles within the absorber. The photonic crystal geometry is optimized to obtain maximum absorption. The photonic crystal provides lossless diffraction of photons, increasing the photon path length within the absorber layer. The simulation predicts significantly enhanced photon harvesting between 600 and 775?nm below the band edge, and an absorption increase by more than a factor of 10 near the band edge. The optical path length ratio can exceed the classical limit predicted for randomly roughened scattering surfaces at most wavelengths near the band edge. The optical modeling is performed with a rigorous scattering matrix approach where Maxwell's equations are solved in Fourier space.

  19. Ag-Pd-Cu alloy inserted transparent indium tin oxide electrodes for organic solar cells

    SciTech Connect

    Kim, Hyo-Joong; Seo, Ki-Won; Kim, Han-Ki; Noh, Yong-Jin; Na, Seok-In

    2014-09-01

    The authors report on the characteristics of Ag-Pd-Cu (APC) alloy-inserted indium tin oxide (ITO) films sputtered on a glass substrate at room temperature for application as transparent anodes in organic solar cells (OSCs). The effect of the APC interlayer thickness on the electrical, optical, structural, and morphological properties of the ITO/APC/ITO multilayer were investigated and compared to those of ITO/Ag/ITO multilayer electrodes. At the optimized APC thickness of 8 nm, the ITO/APC/ITO multilayer exhibited a resistivity of 8.55 × 10{sup −5} Ω cm, an optical transmittance of 82.63%, and a figure-of-merit value of 13.54 × 10{sup −3} Ω{sup −1}, comparable to those of the ITO/Ag/ITO multilayer. Unlike the ITO/Ag/ITO multilayer, agglomeration of the metal interlayer was effectively relieved with APC interlayer due to existence of Pd and Cu elements in the thin region of the APC interlayer. The OSCs fabricated on the ITO/APC/ITO multilayer showed higher power conversion efficiency than that of OSCs prepared on the ITO/Ag/ITO multilayer below 10 nm due to the flatness of the APC layer. The improved performance of the OSCs with ITO/APC/ITO multilayer electrodes indicates that the APC alloy interlayer prevents the agglomeration of the Ag-based metal interlayer and can decrease the thickness of the metal interlayer in the oxide-metal-oxide multilayer of high-performance OSCs.

  20. Location of the low-energy 1Ag state in a polythiophene oligomer by two-photon absorption spectroscopy: α-sexithienyl

    NASA Astrophysics Data System (ADS)

    Periasamy, N.; Danieli, R.; Ruani, G.; Zamboni, R.; Taliani, C.

    1992-02-01

    The two-photon excitation spectrum in polycrystalline α-sexithienyl (T6) thin films has been investigated at 4.2 K in the spectral range between 910 and 1180 nm of the fundamental laser radiation. The intense two-photon absorption band at 18 350 cm-1 is assigned to the 21Ag exciton band origin. The comparison of the one-photon and two-photon excitation spectra shows that the lowest ``gerade'' exciton level lies at 898 cm-1 above the lowest one-photon-allowed 1 2Bu exciton level.

  1. Efficient Counter Electrode Manufactured from Ag2 S Nanocrystal Ink for Dye-Sensitized Solar Cells.

    PubMed

    He, Qingquan; Huang, Shoushuang; Zai, Jiantao; Tang, Nianqi; Li, Bo; Qiao, Qiquan; Qian, Xuefeng

    2015-10-19

    It is generally believed that silver or silver-based compounds are not suitable counter electrode (CE) materials for dye-sensitized solar cells (DSSCs) due to the corrosion of the I(-) /I3 (-) redox couple in electrolytes. However, Ag2 S has potential applications in DSSCs for catalyzing I3 (-) reduction reactions because of its high carrier concentration and tiny solubility product constant. In the present work, CE manufactured from Ag2 S nanocrystals ink exhibited efficient electrocatalytic activity in the reduction of I3 (-) to I(-) in DSSCs. The DSSC consisting of Ag2 S CE displayed a higher power conversion efficiency of 8.40 % than that of Pt CE (8.11 %). Moreover, the devices also showed the characteristics of fast activity onset, high multiple start/stop capability and good irradiated stability. The simple composition, easy preparation, stable chemical property, and good catalytic performance make the developed Ag2 S CE as a promising alternative to Pt CE in DSSCs. PMID:26338374

  2. Fire-through Ag contact formation for crystalline Si solar cells using single-step inkjet printing.

    PubMed

    Kim, Hyun-Gang; Cho, Sung-Bin; Chung, Bo-Mook; Huh, Joo-Youl; Yoon, Sam S

    2012-04-01

    Inkjet-printed Ag metallization is a promising method of forming front-side contacts on Si solar cells due to its non-contact printing nature and fine grid resolution. However, conventional Ag inks are unable to punch through the SiN(x) anti-reflection coating (ARC) layer on emitter Si surfaces. In this study, a novel formulation of Ag ink is examined for the formation of fire-through contacts on a SiN(x)-coated Si substrate using the single-step printing of Ag ink, followed by rapid thermal annealing at 800 degrees C. In order to formulate Ag inks with fire-through contact formation capabilities, a liquid etching agent was first formulated by dissolving metal nitrates in an organic solvent and then mixing the resulting solution with a commercial Ag nanoparticle ink at various volume ratios. During the firing process, the dissolved metal nitrates decomposed into metal oxides and acted in a similar manner to the glass frit contained in Ag pastes for screen-printed Ag metallization. The newly formulated ink with a 1 wt% loading ratio of metal oxides to Ag formed finely distributed Ag crystallites on the Si substrate after firing at 800 degrees C for 1 min. PMID:22849181

  3. Study of photon emission by electron capture during solar nuclei acceleration. 3: Photon production evaluations

    NASA Technical Reports Server (NTRS)

    Gallegos, A.; Perez-Peraza, J.; Alvarez, M.

    1985-01-01

    Lower limits of photon fluxes were evaluated from electron capture during acceleration in solar flares, because the arbitrary q sub c asterisk assumed in this work evolves very slow with velocity, probably much more slowly than the physical actual situation: in fact, more emission is expected toward the IR region. Nevertheless the authors claim to show that the factibility of sounding acceleration processes, charge evolution processes and physical parameters of the source itself, by the observational analysis of this kind of emissions. For instance, it would be interesting to search observationally, for the predicted flux and energy drift of F sub e ions interacting with the atomic 0 and F sub e of the source matter, or, even more feasible for the X-ray lines at 4.2 keV and 2.624 + 0.003 KeV from Fe and S ions in ionized Fe at T = 10 to the 7th power K respectively, the 418 + or - 2 eV and 20 + or - 4 eV lines of Fe and S in ionized Fe at 5 x 10 to the 6th power K, which are predicted from Fermi acceleration.

  4. Effect of exciton-spin-orbit-photon interaction in the performance of organic solar cells

    NASA Astrophysics Data System (ADS)

    Narayan, Monishka Rita; Singh, Jai

    2013-02-01

    Photon absorptions leading to singlet and triplet excitonic states in organic solar cells are presented in this study. Applying Fermi's golden rule, the rates of absorption of singlet and triplet excitons are derived using singlet exciton-photon and triplet exciton-spin-orbit-photon-interaction, respectively, as perturbation operators. The rate of triplet absorption depends on the square of the atomic number and hence heavier atoms play the dominant role. Incorporation of heavy metal atoms in the donor organic material enhances the absorption rate and hence absorption, leading of higher generation of excited charge carriers. This increases the conversion efficiency of organic solar cells. The results are compared with experimental studies.

  5. Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures

    NASA Astrophysics Data System (ADS)

    Park, Jung Tae; Chi, Won Seok; Jeon, Harim; Kim, Jong Hak

    2014-02-01

    TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (η) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of η is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements.TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb

  6. E-beam deposited Ag-nanoparticles plasmonic organic solar cell and its absorption enhancement analysis using FDTD-based cylindrical nano-particle optical model.

    PubMed

    Kim, Richard S; Zhu, Jinfeng; Park, Jeung Hun; Li, Lu; Yu, Zhibin; Shen, Huajun; Xue, Mei; Wang, Kang L; Park, Gyechoon; Anderson, Timothy J; Pei, Qibing

    2012-06-01

    We report the plasmon-assisted photocurrent enhancement in Ag-nanoparticles (Ag-NPs) embedded PEDOT:PSS/P3HT:PCBM organic solar cells, and systematically investigate the causes of the improved optical absorption based on a cylindrical Ag-NPs optical model which is simulated with a 3-Dimensional finite difference time domain (FDTD) method. The proposed cylindrical Ag-NPs optical model is able to explain the optical absorption enhancement by the localized surface plasmon resonance (LSPR) modes, and to provide a further understanding of Ag-NPs shape parameters which play an important role to determine the broadband absorption phenomena in plasmonic organic solar cells. A significant increase in the power conversion efficiency (PCE) of the plasmonic solar cell was experimentally observed and compared with that of the solar cells without Ag-NPs. Finally, our conclusion was made after briefly discussing the electrical effects of the fabricated plasmonic organic solar cells. PMID:22714293

  7. Low-dose photons modify liver response to simulated solar particle event protons.

    PubMed

    Gridley, Daila S; Coutrakon, George B; Rizvi, Asma; Bayeta, Erben J M; Luo-Owen, Xian; Makinde, Adeola Y; Baqai, Farnaz; Koss, Peter; Slater, James M; Pecaut, Michael J

    2008-03-01

    The health consequences of exposure to low-dose radiation combined with a solar particle event during space travel remain unresolved. The goal of this study was to determine whether protracted radiation exposure alters gene expression and oxidative burst capacity in the liver, an organ vital in many biological processes. C57BL/6 mice were whole-body irradiated with 2 Gy simulated solar particle event (SPE) protons over 36 h, both with and without pre-exposure to low-dose/low-dose-rate photons ((57)Co, 0.049 Gy total at 0.024 cGy/h). Livers were excised immediately after irradiation (day 0) or on day 21 thereafter for analysis of 84 oxidative stress-related genes using RT-PCR; genes up or down-regulated by more than twofold were noted. On day 0, genes with increased expression were: photons, none; simulated SPE, Id1; photons + simulated SPE, Bax, Id1, Snrp70. Down-regulated genes at this same time were: photons, Igfbp1; simulated SPE, Arnt2, Igfbp1, Il6, Lct, Mybl2, Ptx3. By day 21, a much greater effect was noted than on day 0. Exposure to photons + simulated SPE up-regulated completely different genes than those up-regulated after either photons or the simulated SPE alone (photons, Cstb; simulated SPE, Dctn2, Khsrp, Man2b1, Snrp70; photons + simulated SPE, Casp1, Col1a1, Hspcb, Il6st, Rpl28, Spnb2). There were many down-regulated genes in all irradiated groups on day 21 (photons, 13; simulated SPE, 16; photons + simulated SPE, 16), with very little overlap among groups. Oxygen radical production by liver phagocytes was significantly enhanced by photons on day 21. The results demonstrate that whole-body irradiation with low-dose-rate photons, as well as time after exposure, had a great impact on liver response to a simulated solar particle event. PMID:18302490

  8. Integrated three-dimensional photonic nanostructures for achieving near-unity solar absorption and superhydrophobicity

    NASA Astrophysics Data System (ADS)

    Kuang, Ping; Hsieh, Mei-Li; Lin, Shawn-Yu

    2015-06-01

    In this paper, we proposed and realized 3D photonic nanostructures consisting of ultra-thin graded index antireflective coatings (ARCs) and woodpile photonic crystals. The use of the integrated ARC and photonic crystal structure can achieve broadband, broad-angle near unity solar absorption. The amorphous silicon based photonic nanostructure experimentally shows an average absorption of ˜95% for λ = 400-620 nm over a wide angular acceptance of θ = 0°-60°. Theoretical studies show that a Gallium Arsenide (GaAs) based structure can achieve an average absorption of >95% for λ = 400-870 nm. Furthermore, the use of the slanted SiO2 nanorod ARC surface layer by glancing angle deposition exhibits Cassie-Baxter state wetting, and superhydrophobic surface is obtained with highest water contact angle θCB ˜ 153°. These properties are fundamentally important for achieving maximum solar absorption and surface self-cleaning in thin film solar cell applications.

  9. Micromorph silicon tandem solar cells with fully integrated 3D photonic crystal intermediate reflectors

    NASA Astrophysics Data System (ADS)

    Üpping, J.; Bielawny, A.; Fahr, S.; Rockstuhl, C.; Lederer, F.; Steidl, L.; Zentel, R.; Beckers, T.; Lambertz, A.; Carius, R.; Wehrspohn, R. B.

    2010-05-01

    A 3D photonic intermediate reflector for textured micromorph silicon tandem solar cells has been investigated. In thin-film silicon tandem solar cells consisting of amorphous and microcrystalline silicon with two junctions of a-Si/c-Si, efficiency enhancements can be achieved by increasing the current density in the a-Si top cell providing an optimized current matching at high current densities. For an ideal photon-management between top and bottom cell, a spectrally-selective intermediate reflective layer (IRL) is necessary. We present the first fully-integrated 3D photonic thin-film IRL device incorporated on a planar substrate. Using a ZnO inverted opal structure the external quantum efficiency of the top cell in the spectral region of interest could be enhanced. As an outlook we present the design and the preparation of a 3D self organized photonic crystal structure in a textured micromorph tandem solar cell.

  10. Effect of incorporated PVP/Ag nanoparticles on ZnPc/C60 organic solar cells.

    PubMed

    Heo, Ilsu; Kim, Jinhyun; Yim, Sanggyu

    2013-06-01

    Various sizes of PVP-capped Ag nanoparticles were incorporated in the PEDOT:PSS layer of ZnPc/C60-based small-molecule organic solar cells. The incorporated nanoparticles partially block the incident light, but this was offset by the scattering effect and consequent increase in path lengths through the active organic layers. As a result, the overall power conversion efficiency of the cell increased by approximately 15% when nanoparticles with an average diameter of 24 nm were used. PMID:23862493

  11. CdS and AgBr sensitized eriochrome black T (EBT) dye solar cells

    NASA Astrophysics Data System (ADS)

    Sharma, G. D.; Dube, D. C.; Mathur, S. C.

    1985-11-01

    The photovoltaic and rectification properties of CdS- and AgBr-sensitized Eriochrome Black T dye solar cells have been studied. The dependence of the short-circuit current and the open-circuit voltage on light intensity and electrode material are examined and the variations with electrode material are explained on the basis of the built-in potential developed at the metal-semiconductor interface. Conversion efficiency, fill factor, diode factor and reverse saturation current are also calculated for each cell.

  12. Slow light enhanced singlet exciton fission solar cells with a 126% yield of electrons per photon

    NASA Astrophysics Data System (ADS)

    Thompson, Nicholas J.; Congreve, Daniel N.; Goldberg, David; Menon, Vinod M.; Baldo, Marc A.

    2013-12-01

    Singlet exciton fission generates two triplet excitons per absorbed photon. It promises to increase the power extracted from sunlight without increasing the number of photovoltaic junctions in a solar cell. We demonstrate solar cells with an external quantum efficiency of 126% by enhancing absorption in thin films of the singlet exciton fission material pentacene. The device structure exploits the long photon dwell time at the band edge of a distributed Bragg reflector to achieve enhancement over a broad range of angles. Measuring the reflected light from the solar cell establishes a lower bound of 137% for the internal quantum efficiency.

  13. Slow light enhanced singlet exciton fission solar cells with a 126% yield of electrons per photon

    SciTech Connect

    Thompson, Nicholas J.; Congreve, Daniel N.; Baldo, Marc A. E-mail: baldo@mit.edu; Goldberg, David; Menon, Vinod M. E-mail: baldo@mit.edu

    2013-12-23

    Singlet exciton fission generates two triplet excitons per absorbed photon. It promises to increase the power extracted from sunlight without increasing the number of photovoltaic junctions in a solar cell. We demonstrate solar cells with an external quantum efficiency of 126% by enhancing absorption in thin films of the singlet exciton fission material pentacene. The device structure exploits the long photon dwell time at the band edge of a distributed Bragg reflector to achieve enhancement over a broad range of angles. Measuring the reflected light from the solar cell establishes a lower bound of 137% for the internal quantum efficiency.

  14. Ag nanoparticles-embedded surface plasmonic InGaN-based solar cells via scattering and localized field enhancement.

    PubMed

    Shim, Jae-Phil; Choi, Sang-Bae; Kong, Duk-Jo; Seo, Dong-Ju; Kim, Hyung-Jun; Lee, Dong-Seon

    2016-07-11

    Ag nanoparticles are embedded in intentionally etched micro-circle p-GaN holes by means of a thermal agglomeration process to enhance the light absorption efficiency in InGaN/GaN multi-quantum-well (MQW) solar cells. The Ag nanoparticles are theoretically and experimentally verified to generate the plasmon light scattering and the localized field enhancement near the MQW absorption layer. The external quantum efficiency enhancement at a target wavelength region is demonstrated by matching the plasmon resonance of Ag nanoparticles, resulting in a Jsc improvement of 9.1%. Furthermore, the Ag-nanoparticle-embedded InGaN solar cell is effectively fabricated considering the carrier extraction that more than 70% of F.F. and 2.2 V of high Voc are simultaneously attained. PMID:27410903

  15. Ag nanoparticle-deposited TiO2 nanotube arrays for electrodes of Dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kawamura, Go; Ohmi, Hayato; Tan, Wai Kian; Lockman, Zainovia; Muto, Hiroyuki; Matsuda, Atsunori

    2015-05-01

    Dye-sensitized solar cells composed of a photoanode of Ag nanoparticle (NP)-deposited TiO2 nanotube (TNT) arrays were fabricated. The TNT arrays were prepared by anodizing Ti films on fluorine-doped tin oxide (FTO)-coated glass substrates. Efficient charge transportation through the ordered nanostructure of TNT arrays should be carried out compared to conventional particulate TiO2 electrodes. However, it has been a big challenge to grow TNT arrays on FTO glass substrates with the lengths needed for sufficient light-harvesting (tens of micrometers). In this work, we deposited Ag nanoparticles (NPs) on the wall of TNT arrays to enhance light-harvesting property. Dye-sensitized solar cells with these Ag NP-deposited TNT arrays yielded a higher power conversion efficiency (2.03 %) than those without Ag NPs (1.39 %).

  16. Transparent ITO/Ag-Pd-Cu/ITO multilayer cathode use in inverted organic solar cells

    SciTech Connect

    Kim, Hyo-Joong; Kim, Han-Ki; Lee, Hyun Hwi; Kal, Jinha; Hahn, Jungseok

    2015-10-15

    The characteristics of transparent ITO/Ag-Pd-Cu (APC)/ITO multilayer cathodes were investigated for use in inverted organic solar cells (IOSCs). The insertion of an APC interlayer into the ITO film effectively led to crystallization of the top ITO layer, unlike that in the Ag interlayer, and resulted in a low sheet resistance of 6.55 Ohm/square and a high optical transmittance of 84.14% without post annealing. In addition, the alloying of the Pd and Cu elements into Ag prevented agglomeration and oxidization of the metal interlayer and led to more stable ITO/APC/ITO films under ambient conditions. The microstructure and interfacial structure of the transparent ITO/APC/ITO cathode in the IOSCs were examined in detail by synchrotron X-ray scattering and high resolution transmission electron microscopy. Furthermore, we suggested a possible mechanism to explain the lower PCE of the IOSCs with an ITO/APC/ITO cathode than that of a reference IOSC with a crystalline ITO cathode using the external quantum efficiency of the IOSCs.

  17. Transparent ITO/Ag-Pd-Cu/ITO multilayer cathode use in inverted organic solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Hyo-Joong; Lee, Hyun Hwi; Kal, Jinha; Hahn, Jungseok; Kim, Han-Ki

    2015-10-01

    The characteristics of transparent ITO/Ag-Pd-Cu (APC)/ITO multilayer cathodes were investigated for use in inverted organic solar cells (IOSCs). The insertion of an APC interlayer into the ITO film effectively led to crystallization of the top ITO layer, unlike that in the Ag interlayer, and resulted in a low sheet resistance of 6.55 Ohm/square and a high optical transmittance of 84.14% without post annealing. In addition, the alloying of the Pd and Cu elements into Ag prevented agglomeration and oxidization of the metal interlayer and led to more stable ITO/APC/ITO films under ambient conditions. The microstructure and interfacial structure of the transparent ITO/APC/ITO cathode in the IOSCs were examined in detail by synchrotron X-ray scattering and high resolution transmission electron microscopy. Furthermore, we suggested a possible mechanism to explain the lower PCE of the IOSCs with an ITO/APC/ITO cathode than that of a reference IOSC with a crystalline ITO cathode using the external quantum efficiency of the IOSCs.

  18. Improving solar cell efficiencies by down-conversion of high-energy photons

    NASA Astrophysics Data System (ADS)

    Trupke, T.; Green, M. A.; Wurfel, P.

    2002-08-01

    One of the major loss mechanisms leading to low energy conversion efficiencies of solar cells is the thermalization of charge carriers generated by the absorption of high-energy photons. These losses can largely be reduced in a solar cell if more than one electron-hole pair can be generated per incident photon. A method to realize multiple electron-hole pair generation per incident photon is proposed in this article. Incident photons with energies larger than twice the band gap of the solar cell are absorbed by a luminescence converter, which transforms them into two or more lower energy photons. The theoretical efficiency limit of this system for nonconcentrated sunlight is determined as a function of the solar cell's band gap using detailed balance calculations. It is shown that a maximum conversion efficiency of 39.63% can be achieved for a 6000 K blackbody spectrum and for a luminescence converter with one intermediate level. This is a substantial improvement over the limiting efficiency of 30.9%, which a solar cell exposed directly to nonconcentrated radiation may have under the same assumption of radiative recombination only.

  19. Multiple exciton generation in quantum dots versus singlet fission in molecular chromophores for solar photon conversion.

    PubMed

    Beard, Matthew C; Johnson, Justin C; Luther, Joseph M; Nozik, Arthur J

    2015-06-28

    Both multiple exciton generation (MEG) in semiconductor nanocrystals and singlet fission (SF) in molecular chromophores have the potential to greatly increase the power conversion efficiency of solar cells for the production of solar electricity (photovoltaics) and solar fuels (artificial photosynthesis) when used in solar photoconverters. MEG creates two or more excitons per absorbed photon, and SF produces two triplet states from a single singlet state. In both cases, multiple charge carriers from a single absorbed photon can be extracted from the cell and used to create higher power conversion efficiencies for a photovoltaic cell or a cell that produces solar fuels, like hydrogen from water splitting or reduced carbon fuels from carbon dioxide and water (analogous to biological photosynthesis). The similarities and differences in the mechanisms and photoconversion cell architectures between MEG and SF are discussed. PMID:25987579

  20. No Photon Left Behind: Advanced Optics at ARPA-E for Buildings and Solar Energy

    NASA Astrophysics Data System (ADS)

    Branz, Howard M.

    2015-04-01

    Key technology challenges in building efficiency and solar energy utilization require transformational optics, plasmonics and photonics technologies. We describe advanced optical technologies funded by the Advanced Research Projects Agency - Energy. Buildings technologies include a passive daytime photonic cooler, infra-red computer vision mapping for energy audit, and dual-band electrochromic windows based on plasmonic absorption. Solar technologies include novel hybrid energy converters that combine high-efficiency photovoltaics with concentrating solar thermal collection and storage. Because the marginal cost of thermal energy storage is low, these systems enable generation of inexpensive and dispatchable solar energy that can be deployed when the sun doesn't shine. The solar technologies under development include nanoparticle plasmonic spectrum splitting, Rugate filter interference structures and photovoltaic cells that can operate efficiently at over 400° C.

  1. All-Nonvacuum-Processed CIGS Solar Cells Using Scalable Ag NWs/AZO-Based Transparent Electrodes.

    PubMed

    Wang, Mingqing; Choy, Kwang-Leong

    2016-07-01

    With record cell efficiency of 21.7%, CIGS solar cells have demonstrated to be a very promising photovoltaic (PV) technology. However, their market penetration has been limited due to the inherent high cost of the cells. In this work, to lower the cost of CIGS solar cells, all nonvacuum-processed CIGS solar cells were designed and developed. CIGS absorber was prepared by the annealing of electrodeposited metallic layers in a chalcogen atmosphere. Nonvacuum-deposited Ag nanowires (NWs)/AZO transparent electrodes (TEs) with good transmittance (92.0% at 550 nm) and high conductivity (sheet resistance of 20 Ω/□) were used to replace the vacuum-sputtered window layer. Additional thermal treatment after device preparation was conducted at 220 °C for a few of minutes to improve both the value and the uniformity of the efficiency of CIGS pixel cell on 5 × 5 cm substrate. The best performance of the all-nonvacuum-fabricated CIGS solar cells showed an efficiency of 14.05% with Jsc of 34.82 mA/cm(2), Voc of 0.58 V, and FF of 69.60%, respectively, which is comparable with the efficiency of 14.45% of a reference cell using a sputtered window layer. PMID:27299854

  2. Two-photon interference and coherent control of single InAs quantum dot emissions in an Ag-embedded structure

    SciTech Connect

    Liu, X.; Kumano, H.; Nakajima, H.; Odashima, S.; Asano, T.; Suemune, I.; Kuroda, T.

    2014-07-28

    We have recently reported the successful fabrication of bright single-photon sources based on Ag-embedded nanocone structures that incorporate InAs quantum dots. The source had a photon collection efficiency as high as 24.6%. Here, we show the results of various types of photonic characterizations of the Ag-embedded nanocone structures that confirm their versatility as regards a broad range of quantum optical applications. We measure the first-order autocorrelation function to evaluate the coherence time of emitted photons, and the second-order correlation function, which reveals the strong suppression of multiple photon generation. The high indistinguishability of emitted photons is shown by the Hong-Ou-Mandel-type two-photon interference. With quasi-resonant excitation, coherent population flopping is demonstrated through Rabi oscillations. Extremely high single-photon purity with a g{sup (2)}(0) value of 0.008 is achieved with π-pulse quasi-resonant excitation.

  3. Photonic Design: From Fundamental Solar Cell Physics to Computational Inverse Design

    NASA Astrophysics Data System (ADS)

    Miller, Owen Dennis

    Photonic innovation is becoming ever more important in the modern world. Optical systems are dominating shorter and shorter communications distances, LED's are rapidly emerging for a variety of applications, and solar cells show potential to be a mainstream technology in the energy space. The need for novel, energy-efficient photonic and optoelectronic devices will only increase. This work unites fundamental physics and a novel computational inverse design approach towards such innovation. The first half of the dissertation is devoted to the physics of high-efficiency solar cells. As solar cells approach fundamental efficiency limits, their internal physics transforms. Photonic considerations, instead of electronic ones, are the key to reaching the highest voltages and efficiencies. Proper photon management led to Alta Device's recent dramatic increase of the solar cell efficiency record to 28.3%. Moreover, approaching the Shockley-Queisser limit for any solar cell technology will require light extraction to become a part of all future designs. The second half of the dissertation introduces inverse design as a new computational paradigm in photonics. An assortment of techniques (FDTD, FEM, etc.) have enabled quick and accurate simulation of the "forward problem" of finding fields for a given geometry. However, scientists and engineers are typically more interested in the inverse problem: for a desired functionality, what geometry is needed? Answering this question breaks from the emphasis on the forward problem and forges a new path in computational photonics. The framework of shape calculus enables one to quickly find superior, non-intuitive designs. Novel designs for optical cloaking and sub-wavelength solar cell applications are presented.

  4. Surface plasmon effect of Ag nanodots embedded in amorphous Si window layers deposited on Si solar cells.

    PubMed

    Park, Seungil; Ji, HyungYong; Kim, Myeong Jun; Peck, Jong Hyeon; Kim, Keunjoo

    2014-12-01

    We investigated solar cells containing temperature-dependent Ag nanodots embedded in an amorphous Si thin film layer by using hot-wire chemical vapor deposition in order to improve the properties of crystalline Si solar cells. An Ag thin film with a thickness of 10 nm was deposited by DC sputtering followed by annealing at various temperatures ranging from 250 to 850 degrees C for 15 min under N2 gas. As increasing the annealing temperature, the Ag nanodots were enlarged and the photoreflectances of the samples with Ag nanodots were lower than the reference samples in the spectral range of 200-600 nm, demonstrating the plasmon effect of Ag nanodots. The cell properties on photoluminescence spectra, quantum efficiency, and conversion efficiency were measured with the maximum values for the sample annealed at 450 degrees C, indicating that there exists an optimal size of the Ag nanodots about 15-35 nm to be effective on the enhancement of surface plasmon effect. PMID:25971039

  5. Li and Ag Co-Doped ZnO Photocatalyst for Degradation of RO 4 Dye Under Solar Light Irradiation.

    PubMed

    Dhatshanamurthi, P; Shanthi, M

    2016-06-01

    The synthesis of Li doped Ag-ZnO (Li-Ag-ZnO) has been successfully achieved by a sonochemically assisted precipitation-decomposition method. The synthesized catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), X-ray photoelectron spectra (XPS) and BET surface area measurements. The photocatalytic activity of Li-Ag-ZnO was investigated for the degradation of Reactive orange 4 (RO 4) dye in aqueous solution under solar light irradiation. Co-dopants shift the absorbance of ZnO to the visible region. Li-Ag-ZnO is found to be more efficient than Ag-ZnO, Li-ZnO, commercial ZnO and prepared ZnO at pH 7 for the mineralization of RO 4 dye under solar light irradiation. The influences of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo-mineralization of RO 4 have been analyzed. The mineralization of RO 4 dye has been confirmed by COD measurements. A degradation mechanism is proposed for the degradation of RO 4 under solar light. The catalyst was found to be more stable and reusable. PMID:27427652

  6. Photon recycling across a ultraviolet-blocking layer by luminescence in polymer solar cells

    NASA Astrophysics Data System (ADS)

    Engmann, Sebastian; Machalett, Marie; Turkovic, Vida; Rösch, Roland; Rädlein, Edda; Gobsch, Gerhard; Hoppe, Harald

    2012-08-01

    UV-blocking layers can increase the long term stability of organic solar cell devices; however, they limit the amount of light that can be utilized for energy conversion. We present photon recycling and down-conversion via a luminescent layer across a UV-blocking TiO2 layer. Our results show that the use of an additional UV-blocking layer does not necessarily reduce the overall efficiency of organic solar cells, since the loss in photocurrent due to the UV-absorption loss can be partially compensated using high energy photon down-conversion via luminescence layers.

  7. Solution-processed solar cells based on environmentally friendly AgBiS2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Bernechea, María; Miller, Nichole Cates; Xercavins, Guillem; So, David; Stavrinadis, Alexandros; Konstantatos, Gerasimos

    2016-08-01

    Solution-processed inorganic solar cells are a promising low-cost alternative to first-generation solar cells. Solution processing at low temperatures combined with the use of non-toxic and abundant elements can help minimize fabrication costs and facilitate regulatory acceptance. However, at present, there is no material that exhibits all these features while demonstrating promising efficiencies. Many of the candidates being explored contain toxic elements such as lead or cadmium (perovskites, PbS, CdTe and CdS(Se)) or scarce elements such as tellurium or indium (CdTe and CIGS(Se)/CIS). Others require high-temperature processes such as selenization or sintering, or rely on vacuum deposition techniques (Sb2S(Se)3, SnS and CZTS(Se)). Here, we present AgBiS2 nanocrystals as a non-toxic, earth-abundant material for high-performance, solution-processed solar cells fabricated under ambient conditions at low temperatures (≤100 °C). We demonstrate devices with a certified power conversion efficiency of 6.3%, with no hysteresis and a short-circuit current density of ∼22 mA cm‑2 for an active layer thickness of only ∼35 nm.

  8. Contributions of Ag Nanowires to the Photoelectric Conversion Efficiency Enhancement of TiO2 Dye-Sensitized Solar Cells.

    PubMed

    Liu, Yunyu; She, Guangwei; Qi, Xiaopeng; Mu, Lixuan; Wang, Xuesong; Shi, Wensheng

    2015-09-01

    Ag nanowires (AgNWs) were employed in mesoporous TiO2 dye-sensitized solar cells (DSSCs) to enhance the photoelectric conversion efficiency (PCE). The possible reasons for PCE improvement, i.e., improvement in electron transport and light harvesting due to light scattering and plasmonic resonance effect of AgNWs are investigated. Electrochemical impedance spectra (EIS) study proved that addition of AgNWs can enhance the conductivity of TiO2 thin film photoanode, which is an important reason for the increase of photocurrent. Furthermore, through the comparison experiments as well as the UV-Vis absorption and IPCE characterization, contributions of the light scattering and plasmonic resonance effect to the enhancement of light harvest, and thus PCE of the DSSCs were demonstrated. It was found that fast electron transport of AgNWs played more important role for the PCE improvement than the light harvest enhancement due to light scattering and plasmonic effect. Based on these investigations, the AgNWs modified TiO2 thin film DSSCs were optimized. After integrating AgNWs into the photoanode, the photocurrent increased significantly and PCE increased -50% comparing with the pure TiO2-based DSSCs. PMID:26716285

  9. Zero Secular Torque on Asteroids from Impinging Solar Photons in the YORP Effect: A Simple Proof

    NASA Technical Reports Server (NTRS)

    Rubincam, David Perry; Paddack, Stephen J.

    2010-01-01

    YORP torques, where "YORP" stands for "Yarokovsky-O'Keefe-Radzievskii-Paddack." arise mainly from sun light reflected off a Solar System object and the infrared radiation emi tted by it. We show here, through the most elementary demonstration that we Can devise, that secular torques from impinging solar photons are generally negligible and thus cause little secular evolution of an asteroid's obliquity or spin rate.

  10. See-through dye-sensitized solar cells: photonic reflectors for tandem and building integrated photovoltaics.

    PubMed

    Heiniger, Leo-Philipp; O'Brien, Paul G; Soheilnia, Navid; Yang, Yang; Kherani, Nazir P; Grätzel, Michael; Ozin, Geoffrey A; Tétreault, Nicolas

    2013-10-25

    See-through dye-sensitized solar cells with 1D photonic crystal Bragg reflector photoanodes show an increase in peak external quantum efficiency of 47% while still maintaining high fill factors, resulting in an almost 40% increase in power conversion efficiency. These photoanodes are ideally suited for tandem and building integrated photovoltaics. PMID:23966106

  11. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials.

    PubMed

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D; Hennessy, John J; Carver, Alexander G; Jones, Todd J; Goodsall, Timothy M; Hamden, Erika T; Suvarna, Puneet; Bulmer, J; Shahedipour-Sandvik, F; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L Douglas

    2016-01-01

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100-300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

  12. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

    PubMed Central

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D.; Hennessy, John J.; Carver, Alexander G.; Jones, Todd J.; Goodsall, Timothy M.; Hamden, Erika T.; Suvarna, Puneet; Bulmer, J.; Shahedipour-Sandvik, F.; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L. Douglas

    2016-01-01

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

  13. The Upper Bound on Solar Power Conversion Efficiency Through Photonic Engineering

    NASA Astrophysics Data System (ADS)

    Xu, Yunlu; Munday, Jeremy

    The power conversion efficiency is a key parameter by which different photovoltaic devices are compared. The maximum value can be calculated under steady-state conditions where the photon flux absorbed by the device equals the outgoing flux of particles (also known as the principle of detailed balance). The photonic engineering of a solar cell offers a new alternative for boosting efficiency. We show that, for an ideally photonic engineered solar cell, its efficiency is subject to an upper bound dictated by a generalized form of detailed balance equation where nano-concentration is taken into account. Results under realistic operating conditions and recent experimental studies will also be discussed. Authors acknowledge the University of Maryland for startup funds to initiate this project and support by the National Science Foundation under Grant CBET-1335857.

  14. Satellite project "CORONAS-PHOTON" for study of solar hard radiation

    NASA Astrophysics Data System (ADS)

    Kotov, Yu.; Cor-Phot Team

    "CORONAS-PHOTON" is the Russian mission for study of the solar hard electromagnetic radiation in the very wide energy range from Extreme UV up to high-energy gamma - radiation. GOAL OF PROJECT: The investigation of energy accumulation and its transformation into energy of accelerated particles processes during solar flares; the study of the acceleration mechanisms, propagation and interaction of fast particles in the solar atmosphere; the study of the solar activity correlation with physical-chemical processes in the Earth upper atmosphere. SCIENTIFIC PAYLOAD CAPABILITY Radiation / Energy region / Detector type: Full solar disk X- radiation / 2keV - 2000MeV / Prop. counter; NaI(Tl); Full solar disk X- and γ-radiation / NaI(Tl)/CsI(Na) phoswich; Full solar disk X- and γ-radiation and solar neutrons / 20 - 300MeV / YalO_3(Ce); CsI(Tl); Hard X-ray polarization in large flares / 20 - 150keV / p-terphenyl scatterer and CsI(Na) absorbers; Full solar disk EUV-radiation monitoring / 6 spectral windows in <10 - 130nm / Filtered photodiodes; Solar images in narrow spectral bands and monochromatic emission lines of hot plasma / Emission of HeII, SiXI, FeXXI, FeXXIII, MgXII ions / Multi-layer and Bregg spherical crystal quartz mirrors with CCDs; Additionally, the temporal and energy spectra of electrons (0.2-14MeV), protons (1-61MeV) and nuclei (Z<26, 2-50MeV/nuclon) at the satellite orbit will be registrated by several instruments. MAIN CHARACTERISTICS OF SPACECRAFT: Spacecraft weight: 1900 kg; Orbit type: Circular; Scientific payload weight: 540 kg; Height: 500 km; Orientation to the Sun [arc min]: better 5; Inclination: 82.5 degree; Instability of orientation [deg/s]: less 0.005; Solar - synchronous orbit is under study. Launching date of "CORONAS-PHOTON" spacecraft is 2006.

  15. Elucidating the localized plasmonic enhancement effects from a single Ag nanowire in organic solar cells.

    PubMed

    Liu, Xinfeng; Wu, Bo; Zhang, Qing; Yip, Jing Ngei; Yu, Guannan; Xiong, Qihua; Mathews, Nripan; Sum, Tze Chien

    2014-10-28

    The origins of performance enhancement in hybrid plasmonic organic photovoltaic devices are often embroiled in a complex interaction of light scattering, localized surface plasmon resonances, exciton-plasmon energy transfer and even nonplasmonic effects. To clearly deconvolve the plasmonic contributions from a single nanostructure, we herein investigate the influence of a single silver nanowire (NW) on the charge carriers in bulk heterojunction polymer solar cells using spatially resolved optical spectroscopy, and correlate to electrical device characterization. Polarization-dependent photocurrent enhancements with a maximum of ∼ 36% over the reference are observed when the transverse mode of the plasmonic excitations in the Ag NW is activated. The ensuing higher absorbance and light scattering induced by the electronic motion perpendicular to the NW long axis lead to increased exciton and polaron densities instead of direct surface plasmon-exciton energy transfer. Finite-difference time-domain simulations also validate these findings. Importantly, our study at the single nanostructure level explores the fundamental limits of plasmonic enhancement achievable in organic solar cells with a single plasmonic nanostructure. PMID:25198060

  16. Photon degradation of AlGaAs/GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, Bruce; Kachare, Ram; Iles, Peter

    1988-01-01

    The behavior of GaAs solar cells after photon illumination for a prolonged exposure time is presented. More than 55 OMCVD AlGaAs/GaAs solar cells were exposed for over 400 h to AM0 photons at 28 C in three separate, well-controlled runs. Significant degradation of solar cell efficiency was observed in two out of three runs. Although noticeable losses in the open-circuit voltage, fill factor, and maximum power were observed, no change in the short-circuit current was found. In one of the runs, no change was seen in either the test cells or the control cells. Each cell in this run was protected with a coverglass. The cells in this run had thicker buffer layers and thinner window layers than the cells in the other two runs.

  17. Non-resonant below-bandgap two-photon absorption in quantum dot solar cells

    SciTech Connect

    Li, Tian; Dagenais, Mario

    2015-04-27

    We study the optically nonlinear sub-bandgap photocurrent generation facilitated by an extended tailing distribution of states in an InAs/GaAs quantum dots (QDs) solar cell. The tailing states function as both the energy states for low energy photon absorption and the photocarriers extraction pathway. One of the biggest advantages of our method is that it can clearly differentiate the photocurrent due to one-photon absorption (1PA) process and two-photon absorption (2PA) process. Both 1PA and 2PA photocurrent generation efficiency in an InAs/GaAs QD device operated at 1550 nm have been quantitatively evaluated. A two-photon absorption coefficient β = 5.7 cm/GW is extracted.

  18. Integrated three-dimensional photonic nanostructures for achieving near-unity solar absorption and superhydrophobicity

    SciTech Connect

    Kuang, Ping; Lin, Shawn-Yu; Hsieh, Mei-Li

    2015-06-07

    In this paper, we proposed and realized 3D photonic nanostructures consisting of ultra-thin graded index antireflective coatings (ARCs) and woodpile photonic crystals. The use of the integrated ARC and photonic crystal structure can achieve broadband, broad-angle near unity solar absorption. The amorphous silicon based photonic nanostructure experimentally shows an average absorption of ∼95% for λ = 400–620 nm over a wide angular acceptance of θ = 0°–60°. Theoretical studies show that a Gallium Arsenide (GaAs) based structure can achieve an average absorption of >95% for λ = 400–870 nm. Furthermore, the use of the slanted SiO{sub 2} nanorod ARC surface layer by glancing angle deposition exhibits Cassie-Baxter state wetting, and superhydrophobic surface is obtained with highest water contact angle θ{sub CB} ∼ 153°. These properties are fundamentally important for achieving maximum solar absorption and surface self-cleaning in thin film solar cell applications.

  19. One-pot synthesis of Ag nanoparticle-coated Pb-based glass frit used in crystalline silicon solar cell

    NASA Astrophysics Data System (ADS)

    Zhou, Jian; Gan, Weiping; Tang, Hongbo; Li, Yingfen; Yang, Chao

    2015-03-01

    Deposition of Ag nanoparticles onto the surface of commercial Pb-based glass frit was conducted via a novel and facile one-pot procedure—a modified polyol process. The procedure included two steps: a 5-min pretreatment of the glass frit at 25 °C in a sonication bath and a 1-h electroless plating at 75 °C in a water bath, which only involved AgNO3 and ethylene glycol but without stabilizing agent. The silver-coated glass frit particles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma emission spectrometer and energy dispersive spectroscopy. It was found that the glass frit particles were homogeneously coated with dense crystalline Ag nanoparticles with an average diameter of 15 nm on the surfaces. Electrical performance of the solar cells was improved after the deposition.

  20. New axion and hidden photon constraints from a solar data global fit

    NASA Astrophysics Data System (ADS)

    Vinyoles, N.; Serenelli, A.; Villante, F. L.; Basu, S.; Redondo, J.; Isern, J.

    2015-10-01

    We present a new statistical analysis that combines helioseismology (sound speed, surface helium and convective radius) and solar neutrino observations (the 8B and 7Be fluxes) to place upper limits to the properties of non standard weakly interacting particles. Our analysis includes theoretical and observational errors, accounts for tensions between input parameters of solar models and can be easily extended to include other observational constraints. We present two applications to test the method: the well studied case of axions and axion-like particles and the more novel case of low mass hidden photons. For axions we obtain an upper limit at 3σ for the axion-photon coupling constant of gaγ < 4.1 · 10-10 GeV-1. For hidden photons we obtain the most restrictive upper limit available accross a wide range of masses for the product of the kinetic mixing and mass of χ m < 1.8 ṡ 10-12 eV at 3σ. Both cases improve the previous solar constraints based on the Standard Solar Models showing the power of using a global statistical approach.

  1. Simultaneous broadband light trapping and fill factor enhancement in crystalline silicon solar cells induced by Ag nanoparticles and nanoshells.

    PubMed

    Fahim, Narges F; Jia, Baohua; Shi, Zhengrong; Gu, Min

    2012-09-10

    Crystalline silicon solar cells are predominant and occupying more than 89% of the global solar photovoltaic market. Despite the boom of the innovative solar technologies, few can provide a low-cost radical solution to dramatically boost the efficiency of crystalline silicon solar cells, which has reached plateau in the past ten years. Here, we present a novel strategy to simultaneously achieve dramatic enhancement in the short-circuit current and the fill factor through the integration of Ag plasmonic nanoparticles and nanoshells on the antireflection coating and the screen-printed fingers of monocrystalline silicon solar cells, respectively, by a single step and scalable modified electroless displacement method. As a consequence, up to 35.2% enhancement in the energy conversion efficiency has been achieved due to the plasmonic broadband light trapping and the significant reduction in the series resistance. More importantly, this method can further increase the efficiency of the best performing textured solar cells from 18.3% to 19.2%, producing the highest efficiency cells exceeding the state-of-the-art efficiency of the standard screen-printed solar cells. The dual functions of the Ag nanostructures, reported for the first time here, present a clear contrast to the previous works, where plasmonic nanostructures were integrated into solar cells to achieve the short-circuit current enhancement predominately. Our method offers a facile, cost-effective and scalable pathway for metallic nanostructures to be used to dramatically boost the overall efficiency of the optically thick crystalline silicon solar cells. PMID:23037536

  2. Photocurrent induced by two-photon excitation in ZnTeO intermediate band solar cells

    NASA Astrophysics Data System (ADS)

    Tanaka, Tooru; Miyabara, Masaki; Nagao, Yasuhiro; Saito, Katsuhiko; Guo, Qixin; Nishio, Mitsuhiro; Yu, Kin M.; Walukiewicz, Wladek

    2013-02-01

    Intermediate band (IB) solar cell structures based on ZnTeO highly mismatched alloy were examined to demonstrate a photocurrent induced by a two-photon excitation (TPE) process. Two types of the devices, with and without a blocking layer for the IB, are prepared. The device with a blocked IB exhibits small external quantum efficiency (EQE) in photon energy range in which electron transitions from valence band (VB) to IB take place, implying the electron accumulation in IB. The enhancement of EQE is observed in TPE experiments as a result of electron transition from VB to conduction band via IB.

  3. Photodeposition of Ag2S on TiO2 nanorod arrays for quantum dot-sensitized solar cells

    PubMed Central

    2013-01-01

    Ag2S quantum dots were deposited on the surface of TiO2 nanorod arrays by a two-step photodeposition. The prepared TiO2 nanorod arrays as well as the Ag2S deposited electrodes were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, suggesting a large coverage of Ag2S quantum dots on the ordered TiO2 nanorod arrays. UV–vis absorption spectra of Ag2S deposited electrodes show a broad absorption range of the visible light. The quantum dot-sensitized solar cells (QDSSCs) based on these electrodes were fabricated, and the photoelectrochemical properties were examined. A high photocurrent density of 10.25 mA/cm2 with a conversion efficiency of 0.98% at AM 1.5 solar light of 100 mW/cm2 was obtained with an optimal photodeposition time. The performance of the QDSSC at different incident light intensities was also investigated. The results display a better performance at a lower incident light level with a conversion efficiency of 1.25% at 47 mW/cm2. PMID:23286551

  4. Phase transformations during the Ag-In plating and bonding of vertical diode elements of multijunction solar cells

    SciTech Connect

    Klochko, N. P. Khrypunov, G. S.; Volkova, N. D.; Kopach, V. R.; Lyubov, V. N.; Kirichenko, M. V.; Momotenko, A. V.; Kharchenko, N. M.; Nikitin, V. A.

    2013-06-15

    The conditions of the bonding of silicon multijunction solar cells with vertical p-n junctions using Ag-In solder are studied. The compositions of electrodeposited indium films on silicon wafers silver plated by screen printing and silver and indium films fabricated by layer-by-layer electrochemical deposition onto the surface of silicon vertical diode cells silver plated in vacuum are studied. Studying the electrochemical-deposition conditions, structure, and surface morphology of the grown layers showed that guaranteed bonding is provided by 8-min heat treatment at 400 Degree-Sign C under the pressure of a stack of metallized silicon wafers; however, the ratio of the indium and silver layer thicknesses should not exceed 1: 3. As this condition is satisfied, the solder after wafer bonding has the InAg{sub 3} structure (or InAg{sub 3} with an Ag phase admixture), due to which the junction melting point exceeds 700 Degree-Sign C, which guarantees the functioning of such solar cells under concentrated illumination.

  5. Random lasing in Eu³⁺ doped borate glass-ceramic embedded with Ag nanoparticles under direct three-photon excitation.

    PubMed

    Xu, Xuhui; Zhang, Wenfei; Jin, Limin; Qiu, Jianbei; Yu, Siu Fung

    2015-10-21

    We report the observation of random lasing from Eu(3+) doped borate glass ceramic films embedded with Ag nanoparticles through three-photon absorption at room temperature. Under 1179 nm ultrashort femtosecond pulse excitation, discrete sharp peaks with linewidth ∼0.4 nm emerge randomly from a broad emission band with peak wavelength at ∼612 nm. In addition, the number of sharp peaks increases with the increase of excitation power. We also show that the emission spectrum varies with different observation angles and the corresponding lasing threshold is dependent on the excitation area. Hence, we verify unambiguously that the Eu(3+) doped borate glass ceramic film supports random lasing action via three-photon absorption excitation. In addition, Ag nanoparticles, which act as light scatterers, allow the formation of random microcavities inside the bulk film. PMID:26377118

  6. Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody.

    PubMed

    Zhu, Linxiao; Raman, Aaswath P; Fan, Shanhui

    2015-10-01

    A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13 °C due to radiative cooling. Our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities. PMID:26392542

  7. Common observations of solar X-rays from SPHINX/CORONAS-PHOTON and XRS/MESSENGER

    NASA Astrophysics Data System (ADS)

    Kepa, Anna; Sylwester, Janusz; Sylwester, Barbara; Siarkowski, Marek; Mrozek, Tomasz; Gryciuk, Magdalena; Phillips, Kenneth

    SphinX was a soft X-ray spectrophotometer constructed in the Space Research Centre of Polish Academy of Sciences. The instrument was launched on 30 January 2009 aboard CORONAS-PHOTON satellite as a part of TESIS instrument package. SphinX measured total solar X-ray flux in the energy range from 1 to 15 keV during the period of very low solar activity from 20 February to 29 November 2009. For these times the solar detector (X-ray Spectrometer - XRS) onboard MESSENGER also observed the solar X-rays from a different vantage point. XRS measured the radiation in similar energy range. We present results of the comparison of observations from both instruments and show the preliminary results of physical analysis of spectra for selected flares.

  8. Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody

    PubMed Central

    Zhu, Linxiao; Raman, Aaswath P.; Fan, Shanhui

    2015-01-01

    A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13 °C due to radiative cooling. Our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities. PMID:26392542

  9. Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling

    NASA Astrophysics Data System (ADS)

    Shi, Xinjian; Jeong, Hokyeong; Oh, Seung Jae; Ma, Ming; Zhang, Kan; Kwon, Jeong; Choi, In Taek; Choi, Il Yong; Kim, Hwan Kyu; Kim, Jong Kyu; Park, Jong Hyeok

    2016-06-01

    Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation.

  10. Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling.

    PubMed

    Shi, Xinjian; Jeong, Hokyeong; Oh, Seung Jae; Ma, Ming; Zhang, Kan; Kwon, Jeong; Choi, In Taek; Choi, Il Yong; Kim, Hwan Kyu; Kim, Jong Kyu; Park, Jong Hyeok

    2016-01-01

    Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation. PMID:27324578

  11. Semitransparent inverted organic solar cell with improved absorption and reasonable transparency perception based on the nanopatterned MoO3/Ag/MoO3 anode

    NASA Astrophysics Data System (ADS)

    Tian, Ximin; Zhang, Ye; Hao, Yuying; Cui, Yanxia; Wang, Wenyan; Shi, Fang; Wang, Hua; Wei, Bin; Huang, Wei

    2015-01-01

    We demonstrate an inverted low bandgap semitransparent organic solar cell with improved absorption as well as reasonable transparency perception based on a nanopatterned MoO3/Ag/MoO3 (MAM) multilayer film as the transparent anode under illumination from the MAM side. The integrated absorption efficiency of the active layer at normal hybrid-polarized incidence considering an AM 1.5G solar spectrum is up to 51.69%, increased by 18.53% as compared to that of the equivalent planar device (43.61%) and reaching 77.3% of that of the corresponding opaque nanopatterned device (66.90%). Detailed investigations reveal that the excitation of plasmonic waveguide modes (at transverse magnetic polarization) and photonic modes (at transverse electric polarization) are responsible for the observed enhancement in absorption. Importantly, the proposed device exhibits an average transmittance of up to 28.4% and an average transparency perception of 26.3% for the human eyes under hybrid-polarized light illumination along with a good color rendering property. Additionally, our proposal works very well over a fairly wide angular range.

  12. Electronic structure at the perylene-tetracarboxylic acid dianhydride/Ag(111) interface studied with two-photon photoelectron spectroscopy.

    PubMed

    Sachs, Sönke; Schwalb, Christian H; Marks, Manuel; Schöll, Achim; Reinert, Friedrich; Umbach, Eberhard; Höfer, Ulrich

    2009-10-14

    The electronic structure of the prototype metal/organic contact 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on a Ag(111)-surface has been investigated using time- and angle-resolved two-photon photoelectron spectroscopy (2PPE). Our analysis addresses particularly the nature of the interface state (IS) emerging at the interface due to the substrate-adsorbate interaction [C. H. Schwalb, S. Sachs, M. Marks et al., Phys. Rev. Lett. 101, 146801 (2008)]. Its free-electron-like dispersion and a possible backfolding at the surface Brillouin zone boundaries are discussed. Time-resolved pump-probe experiments reveal the inelastic electron lifetime along the dispersion parabola and show its decrease for increasing parallel momentum. The temperature dependence of the peak linewidth indicates a coupling of the IS to molecular vibrations. Moreover, additional aspects are addressed, such as the determination of the electron attenuation length of photoelectrons for low kinetic energy originating from the IS and the work function change of the sample upon PTCDA adsorption with very high energy resolution. PMID:19831458

  13. A new architecture as transparent electrodes for solar and IR applications based on photonic structures via soft lithography

    SciTech Connect

    Kuang, Ping

    2011-01-01

    Transparent conducting electrodes with the combination of high optical transmission and good electrical conductivity are essential for solar energy harvesting and electric lighting devices. Currently, indium tin oxide (ITO) is used because ITO offers relatively high transparency (>80%) to visible light and low sheet resistance (Rs = 10 ohms/square (Ω /2)) for electrical conduction. However, ITO is costly due to limited indium reserves, and it is brittle. These disadvantages have motivated the search for other conducting electrodes with similar or better properties. There has been research on a variety of electrode structures involving carbon nanotube networks, graphene films, nanowire and nanopatterned meshes and grids. Due to their novel characteristics in light manipulation and collection, photonic crystal structures show promise for further improvement. Here, we report on a new architecture consisting of nanoscale high aspect ratio metallic photonic structures as transparent electrodes fabricated via a combination of processes. For (Au) and silver (Ag) structures, the visible light transmission can reach as high as 80%, and the sheet resistance of the structure can be as low as 3.2Ω /2. The optical transparency of the high aspect ratio metal structures at visible wavelength range is comparable to that of ITO glass, while their sheet resistance is more than 3 times lower, which indicates a much higher electrical conductivity of the metal structures. Furthermore, the high aspect ratio metal structures have very high infrared (IR) reflection (90%) for the transverse magnetic (TM) mode, which can lead to the development of fabrication of metallic structures as IR filters for heat control applications. Investigations of interdigitated structures based on the high aspect ratio metal electrodes are ongoing to study the feasibility in smart window applications in light transmission modulation.

  14. Integration of biological photonic crystals in dye-sensitized solar cells for enhanced photocurrent generation

    NASA Astrophysics Data System (ADS)

    Campbell, Jeremy; Rorrer, Greg

    2013-10-01

    Dye-sensitized solar cells (DSSCs) rely on a network of titanium dioxide nanoparticles for electron transport and must balance carrier generation and collection. Adding photonic structures may increase light capture without affecting carrier collection. Diatoms are single-celled algae that biologically fabricate silicon dioxide cell walls which resemble photonic crystal slabs. We present a simple fabrication strategy that allows for uniform and controlled placement of biosilica within DSSCs. Integration of biosilica reduces photoanode transmittance to less than 5% prior to dye sensitization at loading levels as low as 6 wt% biosilica. Increased biosilica loading (17 wt%) provides additional enhancements in photocurrent generation. Reflectance measurements suggest that the enhancement results from the combined effects of photonic resonance and Mie scattering. Overall efficiency of these devices is improved by 8% and 14%, respectively.

  15. Materials, Interfaces, and Photon Confiement in Dye-Sensitized Solar Cells

    SciTech Connect

    Lee, B.; Hwang, D.; Guo, P. J.; Ho, S. T.; Buchholtz, D. B.; Wang, C. Y.; Chang, R.P.H.

    2010-11-18

    A series of experiments have been carried out to study the effects of materials quality, surface and interfacial modification, and photon confinement on standard dye-sensitized solar cells. For these studies, both physical and optical characterization of the materials has been performed in detail. In addition, DC and AC impedance measurements along with kinetic charge-transport modeling of experimental results have yielded information on how to systematically optimize the cell efficiency. The same kinetic model has been used to interpret the results of a series of experiments on interfacial modification studies using fluorine etching in combination with TiCl{sub 4} surface treatment. By using specially designed photonic crystals to confine the photons in the cells, it is shown that the best cell efficiency can be further increased by about 13%.

  16. Nano Ag-enhanced energy conversion efficiency in standard commercial pc-Si solar cells and numerical simulations with finite difference time domain method

    NASA Astrophysics Data System (ADS)

    Yu, Jing; Shao, Weijia; Zhou, Yao; Wang, Huijie; Liu, Xiao; Xu, Xiaoliang

    2013-11-01

    Nano Ag-enhanced energy conversion efficiency (ECE) in one standard commercial pc-Si solar cell utilizing the forward scattering by Ag nanoparticles on surface has been researched experimentally and simulatively in this paper. Directly assembling Ag nanoparticles (with size about 100 nm) on the surface, it is found when the particle surface coverage is 10%, the ECE and the short circuit current density are increased by 2.8% and 1.4%, respectively. Without changing any existing structure of the ready-made solar cell, this facile and efficient method has huger applications than other methods.

  17. Light trapping regimes in thin-film silicon solar cells with a photonic pattern.

    PubMed

    Zanotto, Simone; Liscidini, Marco; Andreani, Lucio Claudio

    2010-03-01

    We present a theoretical study of crystalline and amorphous silicon thin-film solar cells with a periodic pattern on a sub-micron scale realized in the silicon layer and filled with silicon dioxide right below a properly designed antireflection (AR) coating. The study and optimization of the structure as a function of all the photonic lattice parameters, together with the calculation of the absorption in a single layer, allows to identify the different roles of the periodic pattern in determining an increase of the absorbance. From one side, the photonic crystal and the AR coating act as impedance matching layers, thus minimizing reflection of incident light over a particularly wide range of frequencies. Moreover a strong absorption enhancement is observed when the incident light is coupled into the quasi guided modes of the photonic slab. We found a substantial increase of the short-circuit current when the parameters are properly optimized, demonstrating the advantage of a wavelength-scale, photonic crystal based approach for patterning of thin-film silicon solar cells. PMID:20389438

  18. Plasmonic and photonic designs for light trapping in thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ji, Liming

    Thin film solar cells are promising to realize cheap solar energy. Compared to conventional wafer cells, they can reduce the use of semiconductor material by 90%. The efficiency of thin film solar cells, however, is limited due to insufficient light absorption. Sufficient light absorption at the bandgap of semiconductor requires a light path more than 10x the thickness of the semiconductor. Advanced designs for light trapping are necessary for solar cells to absorb sufficient light within a limited volume of semiconductor. The goal is to convert the incident light into a trapped mode in the semiconductor layer. In this dissertation, a critical review of currently used methods for light trapping in solar cells is presented. The disadvantage of each design is pointed out including insufficient enhancement, undesired optical loss and undesired loss in carrier transport. The focus of the dissertation is light trapping by plasmonic and photonic structures in thin film Si solar cells. The performance of light trapping by plasmonic structures is dependent on the efficiency of photon radiation from plasmonic structures. The theory of antenna radiation is used to study the radiation by plasmonic structures. In order to achieve efficient photon radiation at a plasmonic resonance, a proper distribution of surface charges is necessary. The planar fishnet structure is proposed as a substitution for plasmonic particles. Large particles are required in order to resonate at the bandgap of semiconductor material. Hence, the resulting overall thickness of solar cells with large particles is large. Instead, the resonance of fishnet structure can be tuned without affecting the overall cell thickness. Numerical simulation shows that the enhancement of light absorption in the active layer is over 10x compared to the same cell without fishnet. Photons radiated from the resonating fishnet structure travel in multiple directions within the semiconductor layer. There is enhanced field

  19. Optically enhanced photon recycling in mechanically stacked multijunction solar cells

    DOE PAGESBeta

    Steiner, Myles A.; Geisz, John F.; Ward, J. Scott; Garcia, Ivan; Friedman, Daniel J.; King, Richard R.; Chiu, Philip T.; France, Ryan M.; Duda, Anna; Olavarria, Waldo J.; et al

    2015-11-09

    Multijunction solar cells can be fabricated by mechanically bonding together component cells that are grown separately. Here, we present four-junction four-terminal mechanical stacks composed of GaInP/GaAs tandems grown on GaAs substrates and GaInAsP/GaInAs tandems grown on InP substrates. The component cells were bonded together with a low-index transparent epoxy that acts as an angularly selective reflector to the GaAs bandedge luminescence, while simultaneously transmitting nearly all of the subbandgap light. As determined by electroluminescence measurements and optical modeling, the GaAs subcell demonstrates a higher internal radiative limit and, thus, higher subcell voltage, compared with GaAs subcells without the epoxy reflector.more » The best cells demonstrate 38.8 ± 1.0% efficiency under the global spectrum at 1000 W/m2 and ~ 42% under the direct spectrum at ~100 suns. As a result, eliminating the series resistance is the key challenge for further improving the concentrator cells.« less

  20. Optically enhanced photon recycling in mechanically stacked multijunction solar cells

    SciTech Connect

    Steiner, Myles A.; Geisz, John F.; Ward, J. Scott; Garcia, Ivan; Friedman, Daniel J.; King, Richard R.; Chiu, Philip T.; France, Ryan M.; Duda, Anna; Olavarria, Waldo J.; Young, Michelle; Kurtz, Sarah R.

    2015-11-09

    Multijunction solar cells can be fabricated by mechanically bonding together component cells that are grown separately. Here, we present four-junction four-terminal mechanical stacks composed of GaInP/GaAs tandems grown on GaAs substrates and GaInAsP/GaInAs tandems grown on InP substrates. The component cells were bonded together with a low-index transparent epoxy that acts as an angularly selective reflector to the GaAs bandedge luminescence, while simultaneously transmitting nearly all of the subbandgap light. As determined by electroluminescence measurements and optical modeling, the GaAs subcell demonstrates a higher internal radiative limit and, thus, higher subcell voltage, compared with GaAs subcells without the epoxy reflector. The best cells demonstrate 38.8 ± 1.0% efficiency under the global spectrum at 1000 W/m2 and ~ 42% under the direct spectrum at ~100 suns. As a result, eliminating the series resistance is the key challenge for further improving the concentrator cells.

  1. Light trapping in thin film solar cells using photonic engineering device concepts

    NASA Astrophysics Data System (ADS)

    Mutitu, James Gichuhi

    In this era of uncertainty concerning future energy solutions, strong reservations have arisen over the continued use and pursuit of fossil fuels and other conventional sources of energy. Moreover, there is currently a strong and global push for the implementation of stringent measures, in order to reduce the amount of green house gases emitted by every nation. As a consequence, there has emerged a sudden and frantic rush for new renewable energy solutions. In this world of renewable energy technologies is where we find photovoltaic (PV) technology today. However, as is, there are still many issues that need to be addressed before solar energy technologies become economically viable and available to all people, in every part of the world. This renewed interest in the development of solar electricity, has led to the advancement of new avenues that address the issues of cost and efficiency associated with PV. To this end, one of the prominent approaches being explored is thin film solar cell (TFSC) technology, which offers prospects of lower material costs and enables larger units of manufacture than conventional wafer based technology. However, TFSC technologies suffer from one major problem; they have lower efficiencies than conventional wafer based solar cell technologies. This lesser efficiency is based on a number of reasons, one of which is that with less material, there is less volume for the absorption of incident photons. This shortcoming leads to the need for optical light trapping; which is concerned with admitting the maximum amount of light into the solar cell and keeping the light within the structure for as long as possible. In this thesis, I present the fundamental scientific ideas, practice and methodology behind the application of photonic engineering device concepts to increase the light trapping capacity of thin film solar cells. In the introductory chapters, I develop the basic ideas behind light trapping in a sequential manner, where the effects

  2. Analysis and simulation of incident photon to current efficiency in dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Gentilini, D.; D'Ercole, D.; Gagliardi, A.; Brunetti, A.; Reale, A.; Brown, T.; Di Carlo, A.

    2010-01-01

    Conversion of solar energy into electricity is a challenging issue of today's renewable energy. Electrochemical dye solar cells (DSC), based on nanostructured TiO 2 particles are a very promising class of photovoltaic devices [6]. The mechanism beyond the conversion of the light is quite different from any other solid state solar cell, resulting from the interplay of a fine tuning of the energy levels of the cell components and a delicate fabrication process. This complexity needs a reliable transport model, able to catch the device as a whole and applicable to experimental set up. We developed an extension of TiberCAD [7] code to simulate such kind of devices and compared the calculation with incident photon to current efficiency (IPCE) measurements.

  3. Mass breakdown model of solar-photon sail shuttle: The case for Mars

    NASA Astrophysics Data System (ADS)

    Vulpetti, Giovanni; Circi, Christian

    2016-02-01

    The main aim of this paper is to set up a many-parameter model of mass breakdown to be applied to a reusable Earth-Mars-Earth solar-photon sail shuttle, and analyze the system behavior in two sub-problems: (1) the zero-payload shuttle, and (2) given the sailcraft sail loading and the gross payload mass, find the sail area of the shuttle. The solution to the subproblem-1 is of technological and programmatic importance. The general analysis of subproblem-2 is presented as a function of the sail side length, system mass, sail loading and thickness. In addition to the behaviors of the main system masses, useful information for future work on the sailcraft trajectory optimization is obtained via (a) a detailed mass model for the descent/ascent Martian Excursion Module, and (b) the fifty-fifty solution to the sailcraft sail loading breakdown equation. Of considerable importance is the evaluation of the minimum altitude for the rendezvous between the ascent rocket vehicle and the solar-photon sail propulsion module, a task performed via the Mars Climate Database 2014-2015. The analysis shows that such altitude is 300 km; below it, the atmospheric drag prevails over the solar-radiation thrust. By this value, an example of excursion module of 1500 kg in total mass is built, and the sailcraft sail loading and the return payload are calculated. Finally, the concept of launch opportunity-wide for a shuttle driven by solar-photon sail is introduced. The previous fifty-fifty solution may be a good initial guess for the trajectory optimization of this type of shuttle.

  4. High temperature solar photon engines. [heat engines for terrestrial and space-based solar power plants

    NASA Technical Reports Server (NTRS)

    Hertzberg, A.; Decher, R.; Mattick, A. T.; Lau, C. V.

    1978-01-01

    High temperature heat engines designed to make maximum use of the thermodynamic potential of concentrated solar radiation are described. Plasmas between 2000 K and 4000 K can be achieved by volumetric absorption of radiation in alkali metal vapors, leading to thermal efficiencies up to 75% for terrestrial solar power plants and up to 50% for space power plants. Two machines capable of expanding hot plasmas using practical technology are discussed. A binary Rankine cycle uses fluid mechanical energy transfer in a device known as the 'Comprex' or 'energy exchanger.' The second machine utilizes magnetohydrodynamics in a Brayton cycle for space applications. Absorption of solar energy and plasma radiation losses are investigated for a solar superheater using potassium vapor.

  5. Plasmonic Ag@oxide nanoprisms for enhanced performance of organic solar cells.

    PubMed

    Du, Peng; Jing, Pengtao; Li, Di; Cao, Yinghui; Liu, Zhenyu; Sun, Zaicheng

    2015-05-01

    Localized surface plasmon resonance (LSPR), light scattering, and lowering the series resistance of noble metal nanoparticles (NPs) provide positive effect on the performance of photovoltaic device. However, the exciton recombination on the noble metal NPs accompanying above influences will deteriorate the performance of device. In this report, surface-modified Ag@oxide (TiO2 or SiO2 ) nanoprisms with 1-2 nm shell thickness are developed. The thin film composed of P3HT/Ag@oxides and P3HT:PCBM/Ag@oxides is investigated by absorption, photoluminescence (PL), and transient absorption spectroscopy. The results show a significant absorption, PL enhancement, and long-lived photogenerated polaron in the P3HT/Ag@TiO2 film, indicating the increase of photogenerated exciton population by LSPR of Ag nanoprisms. In the case of P3HT/Ag nanoprisms, partial PL quench and relatively short-lived photogenerated polaron are observed. That indicates that the oxides layer can effectively avoid the exciton recombination. When the Ag@oxide nanoprisms are introduced into the active layer of P3HT:PCBM photovoltaic devices, about 31% of power conversion efficiency enhancement is obtained relative to the reference cell. All these results indicate that Ag@oxides can enhance the performance of the cell, at the same time the ultrathin oxide shell prevents from the exciton recombination. PMID:25641914

  6. Semitransparent inverted polymer solar cells with MoO3/Ag/MoO3 as transparent electrode

    NASA Astrophysics Data System (ADS)

    Tao, Chen; Xie, Guohua; Liu, Caixia; Zhang, Xindong; Dong, Wei; Meng, Fanxu; Kong, Xiangzi; Shen, Liang; Ruan, Shengping; Chen, Weiyou

    2009-08-01

    Semitransparent inverted polymer solar cells were developed using thermally evaporable MoO3/Ag/MoO3 as transparent anode. The ultrathin inner MoO3 layer was introduced as a buffer layer to improve hole collection, while the outer MoO3 layer served as a light coupling layer to enhance optical transmittance of the device. The dependence of the device performances on the thickness of the outer MoO3 layer was investigated. The results showed that the addition of the outer MoO3 layer improves the transmittance of the anode compared to MoO3/Ag anode and the performances of the semitransparent devices with the outer MoO3 layer are improved due to the reduced series resistance.

  7. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Qi; Liu, Fang; Liu, Yuxiang; Cui, Kaiyu; Feng, Xue; Zhang, Wei; Huang, Yidong

    2013-07-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The power conversion efficiency (PCE) of DSCs is enhanced by 16% from 5.26% to 6.09% by incorporating 2.38 wt% Au-Ag alloy popcorn NPs. Moreover, by adding a scattering layer on the exterior of the counter electrode, the popcorn NPs demonstrate an even stronger ability to increase the PCE by 32% from 5.94% to 7.85%, which results from the more efficient excitation of the LSP mode on the popcorn NPs.

  8. Photonic and plasmonic structures for enhancing efficiency of thin film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Pattnaik, Sambit

    Crystalline silicon solar cells use high cost processing techniques as well as thick materials that are ˜ 200µm thick to convert solar energy into electricity. From a cost viewpoint, it is highly advantageous to use thin film solar cells which are generally made in the range of 0.1-3µm in thickness. Due to this low thickness, the quantity of material is greatly reduced and so is the number and complexity of steps involved to complete a device, thereby allowing a continuous processing capability improving the throughput and hence greatly decreasing the cost. This also leads to faster payback time for the end user of the photovoltaic panel. In addition, due to the low thickness and the possibility of deposition on flexible foils, the photovoltaic (PV) modules can be flexible. Such flexible PV modules are well suited for building-integrated applications and for portable, foldable, PV power products. For economical applications of solar cells, high efficiency is an important consideration. Since Si is an indirect bandgap material, a thin film of Si needs efficient light trapping to achieve high optical absorption. The previous work in this field has been mostly based on randomly textured back reflectors. In this work, we have used a novel approach, a periodic photonic and plasmonic structure, to optimize current density of the devices by absorbing longer wavelengths without hampering other properties. The two dimensional diffraction effect generated by a periodic structure with the plasmonic light concentration achieved by silver cones to efficiently propagate light in the plane at the back surface of a solar cell, achieves a significant increase in optical absorption. Using such structures, we achieved a 50%+ increase in short circuit current in a nano-crystalline (nc-Si) solar cell relative to stainless steel. In addition to nc-Si solar cells on stainless steel, we have also used the periodic photonic structure to enhance optical absorption in amorphous cells and

  9. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting

    PubMed Central

    Kim, Tae Woo; Ping, Yuan; Galli, Giulia A.; Choi, Kyoung-Shin

    2015-01-01

    n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (∼2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effectively reduces the bandgap by ∼0.2 eV but also increases the majority carrier density and mobility, enhancing electron–hole separation. The effect of nitrogen incorporation and oxygen vacancies on the electronic band structure and charge transport of bismuth vanadate are systematically elucidated by ab initio calculations. Owing to simultaneous enhancements in photon absorption and charge transport, the applied bias photon-to-current efficiency of nitrogen-treated BiVO4 for solar water splitting exceeds 2%, a record for a single oxide photon absorber, to the best of our knowledge. PMID:26498984

  10. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting

    NASA Astrophysics Data System (ADS)

    Kim, Tae Woo; Ping, Yuan; Galli, Giulia A.; Choi, Kyoung-Shin

    2015-10-01

    n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (~2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effectively reduces the bandgap by ~0.2 eV but also increases the majority carrier density and mobility, enhancing electron-hole separation. The effect of nitrogen incorporation and oxygen vacancies on the electronic band structure and charge transport of bismuth vanadate are systematically elucidated by ab initio calculations. Owing to simultaneous enhancements in photon absorption and charge transport, the applied bias photon-to-current efficiency of nitrogen-treated BiVO4 for solar water splitting exceeds 2%, a record for a single oxide photon absorber, to the best of our knowledge.

  11. Displacement Damage Effects in Solar Cells: Mining Damage From the Microelectronics and Photonics Test Bed Space Experiment

    NASA Technical Reports Server (NTRS)

    Hardage, Donna (Technical Monitor); Walters, R. J.; Morton, T. L.; Messenger, S. R.

    2004-01-01

    The objective is to develop an improved space solar cell radiation response analysis capability and to produce a computer modeling tool which implements the analysis. This was accomplished through analysis of solar cell flight data taken on the Microelectronics and Photonics Test Bed experiment. This effort specifically addresses issues related to rapid technological change in the area of solar cells for space applications in order to enhance system performance, decrease risk, and reduce cost for future missions.

  12. A facile approach to prepare silicon-based Pt-Ag tubular dendritic nano-forests (tDNFs) for solar-light-enhanced methanol oxidation reaction.

    PubMed

    Lin, Chun-Ting; Shiao, Ming-Hua; Chang, Mao-Nan; Chu, Nancy; Chen, Yu-Wei; Peng, Yu-Hsuan; Liao, Bo-Huei; Huang, Hung Ji; Hsiao, Chien-Nan; Tseng, Fan-Gang

    2015-01-01

    In this paper, a facile two-step Galvanic replacement reaction (GRR) is proposed to prepare Pt-Ag tubular dendritic nano-forests (tDNFs) in ambient condition for enhancing methanol oxidation reaction (MOR) under solar illumination. In the first GRR, a homogeneous layer of silver dendritic nano-forests (DNFs) with 10 μm in thickness was grown on Si wafer in 5 min in silver nitride (AgNO3) and buffer oxide etchant (BOE) solution. In the second GRR, we utilized chloroplatinic acid (H2PtCl6) as the precursor for platinum (Pt) deposition to further transform the prepared Ag DNFs into Pt-Ag tDNFs. The catalytic performance and solar response of the Pt-Ag tDNFs toward methanol electro-oxidation are also studied by cyclic voltammetry (CV) and chronoamperometry (CA). The methanol oxidation current was boosted by 6.4% under solar illumination on the Pt-Ag tDNFs due to the induced localized surface plasmon resonance (LSPR) on the dendritic structure. Current results provide a cost-effective and facile approach to prepare solar-driven metallic electrodes potentially applicable to photo-electro-chemical fuel cells. PMID:25852370

  13. A facile approach to prepare silicon-based Pt-Ag tubular dendritic nano-forests (tDNFs) for solar-light-enhanced methanol oxidation reaction

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Ting; Shiao, Ming-Hua; Chang, Mao-Nan; Chu, Nancy; Chen, Yu-Wei; Peng, Yu-Hsuan; Liao, Bo-Huei; Huang, Hung Ji; Hsiao, Chien-Nan; Tseng, Fan-Gang

    2015-02-01

    In this paper, a facile two-step Galvanic replacement reaction (GRR) is proposed to prepare Pt-Ag tubular dendritic nano-forests (tDNFs) in ambient condition for enhancing methanol oxidation reaction (MOR) under solar illumination. In the first GRR, a homogeneous layer of silver dendritic nano-forests (DNFs) with 10 μm in thickness was grown on Si wafer in 5 min in silver nitride (AgNO3) and buffer oxide etchant (BOE) solution. In the second GRR, we utilized chloroplatinic acid (H2PtCl6) as the precursor for platinum (Pt) deposition to further transform the prepared Ag DNFs into Pt-Ag tDNFs. The catalytic performance and solar response of the Pt-Ag tDNFs toward methanol electro-oxidation are also studied by cyclic voltammetry (CV) and chronoamperometry (CA). The methanol oxidation current was boosted by 6.4% under solar illumination on the Pt-Ag tDNFs due to the induced localized surface plasmon resonance (LSPR) on the dendritic structure. Current results provide a cost-effective and facile approach to prepare solar-driven metallic electrodes potentially applicable to photo-electro-chemical fuel cells.

  14. Real-Space Microscopic Electrical Imaging of n+-p Junction Beneath Front-Side Ag Contact of Multicrystalline Si Solar Cells

    SciTech Connect

    Jiang, C. S.; Li, Z. G.; Moutinho, H. R.; Liang, L.; Ionkin, A.; Al-Jassim, M. M.

    2012-04-15

    We investigated the quality of the n+-p diffused junction beneath the front-side Ag contact of multicrystalline Si solar cells by characterizing the uniformities of electrostatic potential and doping concentration across the junction using the atomic force microscopy-based electrical imaging techniques of scanning Kelvin probe force microscopy and scanning capacitance microscopy. We found that Ag screen-printing metallization fired at the over-fire temperature significantly degrades the junction uniformity beneath the Ag contact grid, whereas metallization at the optimal- and under-fire temperatures does not cause degradation. Ag crystallites with widely distributed sizes were found at the Ag-grid/emitter-Si interface of the over-fired cell, which is associated with the junction damage beneath the Ag grid. Large crystallites protrude into Si deeper than the junction depth. However, the junction was not broken down; instead, it was reformed on the entire front of the crystallite/Si interface. We propose a mechanism of junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent re-crystallization with incorporation of Ag and other impurities and with formation of crystallographic defects during quenching. The effect of this junction damage on solar cell performance is discussed.

  15. Computational image formation with photon sieves for milli-arcsecond solar imaging

    NASA Astrophysics Data System (ADS)

    Oktem, Figen S.; Kamalabadi, Farzad; Davila, Joseph

    2016-07-01

    A photon sieve is a modification of a Fresnel zone plate in which open zones are replaced by a large number of circular holes. This diffractive imaging element is specially suited to observations at UV and x-ray wavelengths where refractive lenses are not available due to strong absorption of materials, and reflective mirrors are difficult to manufacture with sufficient surface figure accuracy to achieve diffraction-limited resolution. On the other hand, photon sieves enable diffraction-limited imaging with much more relaxed tolerances than conventional imaging technology. In this presentation, we present the capabilities of an instrument concept that is based on computational image formation with photon sieves. The instrument enables high-resolution spectral imaging by distributing the imaging task between a photon sieve system and a computational method. A photon sieve coupled with a moving detector provides measurements from multiple planes. Then computational image formation, which involves deconvolution, is performed in a Bayesian estimation framework to reconstruct the multi-spectral images from these measurements. In addition to diffraction-limited high spatial resolution enabled by photon sieves, this instrument can also achieve higher spectral resolution than the conventional spectral imagers, since the technique offers the possibility of separating nearby spectral components that would not otherwise be possible using wavelength filters. Here, the promising capabilities and the imaging performance are shown for imaging the solar corona at EUV wavelengths. The effectiveness of various potential observing scenarios, the effects of interfering emission lines, and the appropriate form of the cost function for image deconvolution are examined.

  16. Characterization of the (Ag,Cu)(In,Ga)Se2 thin film alloy system for solar cells

    NASA Astrophysics Data System (ADS)

    Boyle, Jonathan

    Energy is the underlying factor to human economic activity, and more energy is projected to be needed in the near future and photovoltaics provide a means to supply that energy. Results presented in this dissertation detail material properties of the (Ag,Cu)(In,Ga)Se2 thin film alloy system for use as a solar cell material. Structural and optical properties were determined via X-ray diffraction and UV/Vis/NIR spectrophotometry, respectively. Structural data was analyzed using JADE 2010 software and optical data was analyzed via two different methods. Results of Ag substitution into Cu(In,Ga)Se2 alloy were reconciled with the Jaffe-Wei-Zunger (JWZ) theoretical model, which relates structural and chemical properties of Cu-based ternary chalcopyrite alloys to their optical properties. Dominant phase of the alloy system was identified as chalcopyrite I-42d, Space group 122, with minor secondary phases and order defect phases. No chalcopyrite-chalcopyrite miscibility gap was present in the alloy compositional space, counter to prior literature on bulk polycrystalline materials and thermodynamic calculations performed here, indicating that Ag was successfully substituted into the chalcopyrite lattice. Lattice constant results were consistent with JWZ model, where a O lattice constant closely follows Vegard's rule, cO lattice constant changes at different rates than aO does with composition, and anion displacement is affected by cation radii. Optical results showed bandgap widening with Ag and Ga substitution across the full compositional space, with bowing parameters shown overall to be invariant with cation substitution, counter to expectations. (Ag+Cu)/(In+Ga) ratio effect on bandgap for a limited set of samples is consistent with p-d hybridization effects from JWZ model.

  17. Leaf photosynthetic and solar-tracking responses of mallow, Malva parviflora, to photon flux density.

    PubMed

    Greer, Dennis H; Thorpe, Michael R

    2009-10-01

    Malva parviflora L. (mallow) is a species that occupies high-light habitats as a weedy invader in orchards and vineyards. Species of the Malvaceae are known to solar track and anecdotal evidence suggests this species may also. How M. parviflora responds physiologically to light in comparison with other species within the Malvaceae remains unknown. Tracking and photosynthetic responses to photon flux density (PFD) were evaluated on plants grown in greenhouse conditions. Tracking ability was assessed in the growth conditions and by exposing leaves to specific light intensities and measuring changes in the angle of the leaf plane. Light responses were also determined by photosynthesis and chlorophyll fluorescence. Leaves followed a heliotropic response which was highly PFD-dependent, with tracking rates increasing in a curvilinear pattern. Maximum tracking rates were up to 20 degrees h(-1) and saturated for light above 1,300 micromol (photons) m(-2) s(-1). This high-light saturation, both for tracking (much higher than the other species), and for photosynthesis, confirmed mallow as a high-light demanding species. Further, because there was no photoinhibition, the leaves could capture the potential of an increased carbon gain in higher irradiance by resorting to solar tracking. Modelling suggested the tracking response could increase the annual carbon gain by as much as 25% compared with leaves that do not track the sun. The various leaf attributes associated with solar tracking, therefore, help to account for the success of this species as a weed in many locations worldwide. PMID:19576789

  18. Inverse Compton Scattering on Solar Photons, Heliospheric Modulation, and Neutrino Astrophysics

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.; Digel, Seth W.; /SLAC

    2006-08-01

    We study the inverse Compton scattering of solar photons by Galactic cosmic-ray electrons. We show that the {gamma}-ray emission from this process is significant with the maximum flux in the direction of the Sun; the angular distribution of the emission is broad. This previously neglected foreground should be taken into account in studies of the diffuse Galactic and extragalactic {gamma}-ray emission. Furthermore, observations by GLAST can be used to monitor the heliosphere and determine the electron spectrum as a function of position from distances as large as Saturn's orbit down to close proximity of the Sun, thus enabling studies of solar modulation in the most extreme case. This paves the way for the determination of other Galactic cosmic-ray species, primarily protons, near the solar surface leading to accurate predictions of {gamma}-rays from pp-interactions in the solar atmosphere. These albedo {gamma}-rays will be observable by GLAST, allowing the study of deep atmospheric layers, magnetic field(s), and cosmic-ray cascade development. The latter is necessary to calculate the neutrino flux from pp-interactions at higher energies (>1 TeV). The corresponding neutrino flux from the Sun can be used as a ''standard candle'' for upcoming km{sup 3} neutrino detectors, such as IceCube. Since the solar core is opaque for very high-energy neutrinos, it may be possible to directly study the mass distribution of the Sun.

  19. Optimal enhancement in conversion efficiency of crystalline Si solar cells using inverse opal photonic crystals as back reflectors

    NASA Astrophysics Data System (ADS)

    Chaouachi, A.; Chtourou, R.; M'nif, A.; Hamzaoui, A. H.

    2015-04-01

    The effect of using inverse opal photonic crystals as back reflectors on the power conversion efficiency of c-Si solar cells is investigated. The reflection spectra of inverse opal photonic crystals with different diameters of air spheres are simulated using the finite difference time domain (FDTD) method. The reflection peaks are correlated with photonic band gaps present in the photonic band gap diagram. Significant improvement in the optical absorption of the crystalline silicon layer is recorded when inverse opal photonic crystals are considered. Physical mechanisms which may contribute to the enhancement of the light absorption are underlined. With higher short-circuit current enhancement possible, and with no corresponding degradation in open-circuit voltage Voc or the fill factor, the power conversion efficiency is increased significantly when inverse opal photonic crystals are used as back reflectors with optimized diameter of air spheres.

  20. Photon management for enhanced open-circuit voltage in nanostructured solar cells

    NASA Astrophysics Data System (ADS)

    Sandhu, S.; Yu, Z.; Fan, S.

    2015-10-01

    We review the recent progress on using pure photonic engineering for voltage enhancement of nanostructured solar cells. These works use a detailed balance analysis for the current-voltage modeling of their devices, while taking into account of intrinsic material nonidealities to determine their fundamental limiting performances. The physics of voltage enhancement in these nanostructures is elucidated and shown to be related to the suppression of thermal emission in the immediate vicinity of the material electronic bandgap. We also review a recent work on using thermal emission suppresion in a single material tandem cell configuration to overcome the Shockley-Queisser limit.

  1. Kind of broad-band photonic valve and its application to silicon solar cells.

    PubMed

    Le Perchec, J

    2012-09-10

    We investigate the dual optical behaviour of a photonic grating interface presenting a more or less important index contrast, showing either efficient broadband reflectivity, either high transmittance within the same spectral window, depending on the direction of the incident light. This behaviour is reminiscent of a diode one and could find interesting applications. A typical example is given for thin crystalline silicon solar cells where the rear side is directly nano-textured to trap light without metal reflector (bifacial device), well compatible with an integration in a photovoltaic module. PMID:23037524

  2. Enhanced photon management in silicon thin film solar cells with different front and back interface texture

    NASA Astrophysics Data System (ADS)

    Tamang, Asman; Hongsingthong, Aswin; Jovanov, Vladislav; Sichanugrist, Porponth; Khan, Bakhtiar A.; Dewan, Rahul; Konagai, Makoto; Knipp, Dietmar

    2016-08-01

    Light trapping and photon management of silicon thin film solar cells can be improved by a separate optimization of the front and back contact textures. A separate optimization of the front and back contact textures is investigated by optical simulations taking realistic device geometries into consideration. The optical simulations are confirmed by experimentally realized 1 μm thick microcrystalline silicon solar cells. The different front and back contact textures lead to an enhancement of the short circuit current by 1.2 mA/cm2 resulting in a total short circuit current of 23.65 mA/cm2 and an energy conversion efficiency of 8.35%.

  3. Enhanced photon management in silicon thin film solar cells with different front and back interface texture

    PubMed Central

    Tamang, Asman; Hongsingthong, Aswin; Jovanov, Vladislav; Sichanugrist, Porponth; Khan, Bakhtiar A.; Dewan, Rahul; Konagai, Makoto; Knipp, Dietmar

    2016-01-01

    Light trapping and photon management of silicon thin film solar cells can be improved by a separate optimization of the front and back contact textures. A separate optimization of the front and back contact textures is investigated by optical simulations taking realistic device geometries into consideration. The optical simulations are confirmed by experimentally realized 1 μm thick microcrystalline silicon solar cells. The different front and back contact textures lead to an enhancement of the short circuit current by 1.2 mA/cm2 resulting in a total short circuit current of 23.65 mA/cm2 and an energy conversion efficiency of 8.35%. PMID:27481226

  4. Enhanced photon management in silicon thin film solar cells with different front and back interface texture.

    PubMed

    Tamang, Asman; Hongsingthong, Aswin; Jovanov, Vladislav; Sichanugrist, Porponth; Khan, Bakhtiar A; Dewan, Rahul; Konagai, Makoto; Knipp, Dietmar

    2016-01-01

    Light trapping and photon management of silicon thin film solar cells can be improved by a separate optimization of the front and back contact textures. A separate optimization of the front and back contact textures is investigated by optical simulations taking realistic device geometries into consideration. The optical simulations are confirmed by experimentally realized 1 μm thick microcrystalline silicon solar cells. The different front and back contact textures lead to an enhancement of the short circuit current by 1.2 mA/cm(2) resulting in a total short circuit current of 23.65 mA/cm(2) and an energy conversion efficiency of 8.35%. PMID:27481226

  5. Synthesis, characterization and evaluation of the photocatalytic performance of Ag-CdMoO{sub 4} solar light driven plasmonic photocatalyst

    SciTech Connect

    Adhikari, Rajesh; Malla, Shova; Gyawali, Gobinda; Sekino, Tohru; Lee, Soo Wohn

    2013-09-01

    Graphical abstract: - Highlights: • Ag-CdMoO{sub 4} solar light driven photocatalyst was successfully synthesized. • Photocatalyst exhibited strong absorption in the visible region. • Photocatalytic activity was significantly enhanced. • Enhanced activity was caused by the SPR effect induced by Ag nanoparticles. - Abstract: Ag-CdMoO{sub 4} plasmonic photocatalyst was synthesized in ethanol/water mixture by photo assisted co-precipitation method at room temperature. As synthesized powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyzer. Photocatalytic activity was evaluated by performing the degradation experiment over methylene blue (MB) and indigo carmine (IC) as model dyes under simulated solar light irradiation. The results revealed that the Ag-CdMoO{sub 4} showed the higher photocatalytic performance as compared to CdMoO{sub 4} nanoparticles. Dispersion of Ag nanoparticles over the surface of CdMoO{sub 4} nanoparticles causes the surface plasmon resonance (SPR) and enhances the broad absorption in the entire visible region of the solar spectrum. Hence, dispersion of Ag nanoparticles over CdMoO{sub 4} nanoparticles could be the better alternative to enhance the absorption of visible light by scheelite crystal family for effective photocatalysis.

  6. Ni/Cu/Ag plated contacts: A study of resistivity and contact adhesion for crystalline-Si solar cells

    NASA Astrophysics Data System (ADS)

    ur Rehman, Atteq; Lee, Sang Hee; Bhopal, Muhammad Fahad; Lee, Soo Hong

    2016-07-01

    Ni/Cu/Ag plated contacts were examined as an alternate to Ag screen printed contacts for silicon (Si) solar cell metallization. To realize a reliable contact for industrial applications, the contact resistance and its adhesion to Si substrates were evaluated. Si surface roughness by picosecond (ps) laser ablation of silicon-nitride (SiNx) antireflection coating (ARC) was done in order to prepare the patterns. The sintering process after Ni/Cu/Ag full metallization in the form of the post-annealing process was applied to investigate the contact resistivity and adhesion. A very low contact resistivity of approximately 0.5 mΩcm2 has been achieved with measurements made by the transfer length method (TLM). Thin finger lines of about 26 μm wide and a line resistance of 0.51 Ω/cm have been realized by plating technology. Improved contact adhesion by combining the ps-laser-ablation and post-annealing process has been achieved. We have shown the peel-off strengths >1 N/mm with a higher average adhesion of 1.9 N/mm. Our pull-tab adhesion tests demonstrate excellent strength well above the wafer breakage force. [Figure not available: see fulltext.

  7. Negative space charge effects in photon-enhanced thermionic emission solar converters

    SciTech Connect

    Segev, G.; Weisman, D.; Rosenwaks, Y.; Kribus, A.

    2015-07-06

    In thermionic energy converters, electrons in the gap between electrodes form a negative space charge and inhibit the emission of additional electrons, causing a significant reduction in conversion efficiency. However, in Photon Enhanced Thermionic Emission (PETE) solar energy converters, electrons that are reflected by the electric field in the gap return to the cathode with energy above the conduction band minimum. These electrons first occupy the conduction band from which they can be reemitted. This form of electron recycling makes PETE converters less susceptible to negative space charge loss. While the negative space charge effect was studied extensively in thermionic converters, modeling its effect in PETE converters does not account for important issues such as this form of electron recycling, nor the cathode thermal energy balance. Here, we investigate the space charge effect in PETE solar converters accounting for electron recycling, with full coupling of the cathode and gap models, and addressing conservation of both electric and thermal energy. The analysis shows that the negative space charge loss is lower than previously reported, allowing somewhat larger gaps compared to previous predictions. For a converter with a specific gap, there is an optimal solar flux concentration. The optimal solar flux concentration, the cathode temperature, and the efficiency all increase with smaller gaps. For example, for a gap of 3 μm the maximum efficiency is 38% and the optimal flux concentration is 628, while for a gap of 5 μm the maximum efficiency is 31% and optimal flux concentration is 163.

  8. Engineering inverse woodpile and woodpile photonic crystal solar cells for light trapping.

    PubMed

    Wang, Baomin; Chen, Kevin P; Leu, Paul W

    2016-06-01

    We demonstrate that inverse woodpile and woodpile photonic crystal nanocrystalline silicon structures may be engineered for light trapping in solar cells. We use finite-difference tim-domain simulations to show that the geometry of these photonic crystals may be varied such that absorption in the infrared, visible, and ultraviolet parts of the spectrum may all be improved. The short-circuit current density and ultimate efficiency are also improved. We found a 77.1% and 106% absorption enhancement in the optimized inverse woodpile and woodpile structures respectively, compared to a nanocrystalline silicon thin film of the equivalent thickness. The inverse woodpile structures may be approximated as a thin film with effective index of refraction, whereas the woodpile structures exhibit resonances from the coupling of TE and TM leaky modes in the stacked cylinders. Woodpile photonic crystal structures exhibit improved performance compared to inverse woodpile structures over a range of equivalent thicknesses and incidence angles. The performance of woodpile structures is also generally insensitive to the diameter, pitch and number of layers, whereas inverse woodpile structures are much more sensitive to morphology. PMID:27109121

  9. Engineering inverse woodpile and woodpile photonic crystal solar cells for light trapping

    NASA Astrophysics Data System (ADS)

    Wang, Baomin; Chen, Kevin P.; Leu, Paul W.

    2016-06-01

    We demonstrate that inverse woodpile and woodpile photonic crystal nanocrystalline silicon structures may be engineered for light trapping in solar cells. We use finite-difference tim-domain simulations to show that the geometry of these photonic crystals may be varied such that absorption in the infrared, visible, and ultraviolet parts of the spectrum may all be improved. The short-circuit current density and ultimate efficiency are also improved. We found a 77.1% and 106% absorption enhancement in the optimized inverse woodpile and woodpile structures respectively, compared to a nanocrystalline silicon thin film of the equivalent thickness. The inverse woodpile structures may be approximated as a thin film with effective index of refraction, whereas the woodpile structures exhibit resonances from the coupling of TE and TM leaky modes in the stacked cylinders. Woodpile photonic crystal structures exhibit improved performance compared to inverse woodpile structures over a range of equivalent thicknesses and incidence angles. The performance of woodpile structures is also generally insensitive to the diameter, pitch and number of layers, whereas inverse woodpile structures are much more sensitive to morphology.

  10. Fabrication of Au@Ag core/shell nanoparticles decorated TiO2 hollow structure for efficient light-harvesting in dye-sensitized solar cells.

    PubMed

    Yun, Juyoung; Hwang, Sun Hye; Jang, Jyongsik

    2015-01-28

    Improving the light-harvesting properties of photoanodes is promising way to enhance the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). We synthesized Au@Ag core/shell nanoparticles decorated TiO2 hollow nanoparticles (Au@Ag/TiO2 HNPs) via sol-gel reaction and chemical deposition. The Au@Ag/TiO2 HNPs exhibited multifunctions from Au@Ag core/shell NPs (Au@Ag CSNPs) and TiO2 hollow nanoparticles (TiO2 HNPs). These Au@Ag CSNPs exhibited strong and broadened localized surface plasmon resonance (LSPR), together with a large specific surface area of 129 m(2) g(-1), light scattering effect, and facile oxidation-reduction reaction of electrolyte from TiO2 HNPs, which resulted in enhancement of the light harvesting. The optimum PCE of η = 9.7% was achieved for the DSSCs using photoanode materials based on TiO2 HNPs containing Au@Ag/TiO2 HNPs (0.2 wt % Au@Ag CSNPs with respect to TiO2 HNPs), which outperformed by 24% enhancement that of conventional photoanodes formed using P25 (η = 7.8%). PMID:25562329

  11. TiInZnO/Ag/TiInZnO multilayer films for transparent conducting electrodes of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Ho-Hyeong; Kim, Eun-Mi; Lee, Kyung-Ju; Park, Jae-Young; Lee, Yu-Ri; Shin, Dong-Chan; Hwang, Tae-Jin; Heo, Gi-Seok

    2014-03-01

    Ti-In-Zn-O (TIZO) and TIZO/Ag/TIZO multilayer transparent films were prepared at room temperature on glass substrates using an RF/DC magnetron sputtering system. The optical and electrical properties of the multilayer structures were examined according to the thickness of each TIZO/Ag/TIZO layer. A transparent and conductive film with a sheet resistance of 11.1 Ω/□ and a transmittance of 86.9% at 550 nm (94.2%, normalized to the glass substrate) was obtained at a TIZO/Ag/TIZO thickness of 100/8/42 nm. The TIZO and TIZO/Ag/TIZO multilayer films exhibited higher mechanical resistances against an increasing load of external scratches than the indium tin oxide (ITO) film. Overall, the properties of the TIZO/Ag/TIZO multilayer films were comparable or superior to those of the ITO/Ag/ITO multilayer. The deposited TIZO/Ag/TIZO multilayer films were used in the fabrication of dye-sensitized solar cells (DSSCs) as the transparent electrode. The TIZO/Ag/TIZO multilayer-based DSSCs exhibited a short circuit photocurrent density of 9.4 mA/cm2, a photocurrent of 613 mV, and an overall cell efficiency of 3.1% at a light intensity of one sun.

  12. Ag plasmonic nanostructures and a novel gel electrolyte in a high efficiency TiO2/CdS solar cell.

    PubMed

    Kumar, P Naresh; Deepa, Melepurath; Srivastava, Avanish Kumar

    2015-04-21

    A novel photoanode architecture with plasmonic silver (Ag) nanostructures embedded in titania (TiO2), which served as the wide band gap semiconducting support and CdS quantum dots (QDs), as light absorbers, is presented. Ag nanostructures were prepared by a polyol method and are comprised of clumps of nanorods, 15-35 nm wide, interspersed with globular nanoparticles and they were characterized by a face centered cubic lattice. Optimization of Ag nanostructures was achieved on the basis of a superior power conversion efficiency (PCE) obtained for the cell with a Ag/TiO2/CdS electrode encompassing a mixed morphology of Ag nano-rods and particles, relative to analogous cells with either Ag nanoparticles or Ag nanorods. Interfacial charge transfer kinetics was unraveled by fluorescence quenching and lifetime studies. Ag nanostructures improve the light harvesting ability of the TiO2/CdS photoanode via (a) plasmonic and scattering effects, which induce both near- and far-field enhancements which translate to higher photocurrent densities and (b) charging effects, whereby, photoexcited electron transfer from TiO2 to Ag is facilitated by Fermi level equilibration. Owing to the spectacular ability of Ag nanostructures to increase light absorption, a greatly increased PCE of 4.27% and a maximum external quantum efficiency of 55% (at 440 nm) was achieved for the cell based on Ag/TiO2/CdS, greater by 42 and 66%, respectively, compared to the TiO2/CdS based cell. In addition, the liquid S(2-) electrolyte was replaced by a S(2-) gel containing fumed silica, and the redox potential, conductivity and p-type conduction of the two were deduced to be comparable. Although the gel based cells showed diminished solar cell performances compared to their liquid counterparts, nonetheless, the Ag/TiO2/CdS electrode continued to outperform the TiO2/CdS electrode. Our studies demonstrate that Ag nanostructures effectively capture a significant chunk of the electromagnetic spectrum and aid QD

  13. High-efficiency polymer solar cells with small photon energy loss

    PubMed Central

    Kawashima, Kazuaki; Tamai, Yasunari; Ohkita, Hideo; Osaka, Itaru; Takimiya, Kazuo

    2015-01-01

    A crucial issue facing polymer-based solar cells is how to manage the energetics of the polymer/fullerene blends to maximize short-circuit current density and open-circuit voltage at the same time and thus the power conversion efficiency. Here we demonstrate that the use of a naphthobisoxadiazole-based polymer with a narrow bandgap of 1.52 eV leads to high open-circuit voltages of approximately 1 V and high-power conversion efficiencies of ∼9% in solar cells, resulting in photon energy loss as small as ∼0.5 eV, which is much smaller than that of typical polymer systems (0.7–1.0 eV). This is ascribed to the high external quantum efficiency for the systems with a very small energy offset for charge separation. These unconventional features of the present polymer system will inspire the field of polymer-based solar cells towards further improvement of power conversion efficiencies with both high short-circuit current density and open-circuit voltage. PMID:26626042

  14. High-efficiency polymer solar cells with small photon energy loss

    NASA Astrophysics Data System (ADS)

    Kawashima, Kazuaki; Tamai, Yasunari; Ohkita, Hideo; Osaka, Itaru; Takimiya, Kazuo

    2015-12-01

    A crucial issue facing polymer-based solar cells is how to manage the energetics of the polymer/fullerene blends to maximize short-circuit current density and open-circuit voltage at the same time and thus the power conversion efficiency. Here we demonstrate that the use of a naphthobisoxadiazole-based polymer with a narrow bandgap of 1.52 eV leads to high open-circuit voltages of approximately 1 V and high-power conversion efficiencies of ~9% in solar cells, resulting in photon energy loss as small as ~0.5 eV, which is much smaller than that of typical polymer systems (0.7-1.0 eV). This is ascribed to the high external quantum efficiency for the systems with a very small energy offset for charge separation. These unconventional features of the present polymer system will inspire the field of polymer-based solar cells towards further improvement of power conversion efficiencies with both high short-circuit current density and open-circuit voltage.

  15. High-efficiency polymer solar cells with small photon energy loss.

    PubMed

    Kawashima, Kazuaki; Tamai, Yasunari; Ohkita, Hideo; Osaka, Itaru; Takimiya, Kazuo

    2015-01-01

    A crucial issue facing polymer-based solar cells is how to manage the energetics of the polymer/fullerene blends to maximize short-circuit current density and open-circuit voltage at the same time and thus the power conversion efficiency. Here we demonstrate that the use of a naphthobisoxadiazole-based polymer with a narrow bandgap of 1.52 eV leads to high open-circuit voltages of approximately 1 V and high-power conversion efficiencies of ∼9% in solar cells, resulting in photon energy loss as small as ∼0.5 eV, which is much smaller than that of typical polymer systems (0.7-1.0 eV). This is ascribed to the high external quantum efficiency for the systems with a very small energy offset for charge separation. These unconventional features of the present polymer system will inspire the field of polymer-based solar cells towards further improvement of power conversion efficiencies with both high short-circuit current density and open-circuit voltage. PMID:26626042

  16. Reduction in the intensity of solar X-ray emission in the 2- to 15-keV photon energy range and heating of the solar corona

    SciTech Connect

    Mirzoeva, I. K.

    2013-04-15

    The time profiles of the energy spectra of low-intensity flares and the structure of the thermal background of the soft X-ray component of solar corona emission over the period of January-February, 2003, are investigated using the data of the RHESSI project. A reduction in the intensity of X-ray emission of the solar flares and the corona thermal background in the 2- to 15-keV photon energy range is revealed. The RHESSI data are compared with the data from the Interball-Geotail project. A new mechanism of solar corona heating is proposed on the basis of the results obtained.

  17. Absorption and quasiguided mode analysis of organic solar cells with photonic crystal photoactive layers.

    PubMed

    Tumbleston, John R; Ko, Doo-Hyun; Samulski, Edward T; Lopez, Rene

    2009-04-27

    We analyze optical absorption enhancements and quasiguided mode properties of organic solar cells with highly ordered nanostructured photoactive layers comprised of the bulk heterojunction blend, poly-3-hexylthiophene/[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) and a low index of refraction conducting material (LICM). This photonic crystal geometry is capable of enhancing spectral absorption by approximately 17% in part due to the excitation of quasiguided modes near the band edge of P3HT:PCBM. A nanostructure thickness between 200 nm and 300 nm is determined to be optimal, while the LICM must have an index of refraction approximately 0.3 lower than P3HT:PCBM to produce absorption enhancements. Quasiguided modes that differ in lifetime by an order of magnitude are also identified and yield absorption that is concentrated in the P3HT:PCBM flash layer. PMID:19399146

  18. Visible photon multiplication in Ce3+-Tb3+ doped borate glasses for enhanced solar cells

    NASA Astrophysics Data System (ADS)

    Yang, Peng; Chen, Baojie; Shen, Lifan; Bun Pun, Edwin Yue; Lin, Hai

    2014-11-01

    Visible photon multiplication is exposed in the Ce3+-Tb3+ doped alkaline-earth borate (LKZBSB) glass system. Efficient green and blue fluorescences originate from Tb3+ and Ce3+ emitting centres, respectively. Evaluation of absolute spectral parameters reveals that the quantum yield of Tb3+ single doped LKZBSB glasses is ~8% under UVA radiation. Furthermore, with the introduction of Ce3+ into the Tb3+ doping system, the effective excitation wavelength range and the emission intensity of Tb3+ in LKZBSB glasses are remarkably expanded and improved by a maximum sensitization factor of ~52 in the UVB spectral region. These results demonstrate that the Ce3+-Tb3+ doped LKZBSB glass system has promising potential as an efficient UV → Visible radiation conversion layer for the enhancement of solar cell efficiency, including cells employed in outer space.

  19. Solar-photocatalytic disinfection of Vibrio cholerae by using Ag@ZnO core-shell structure nanocomposites.

    PubMed

    Das, Sourav; Sinha, Sayantan; Suar, Mrutyunjay; Yun, Soon-Il; Mishra, Amrita; Tripathy, Suraj K

    2015-01-01

    Disinfection of Gram-negative bacterium Vibrio cholerae 569B in aqueous matrix by solar-photocatalysis mediated by Ag@ZnO core-shell structure nanocomposite particles was investigated. Silver nanoparticles are synthesized by the reduction of silver perchlorate followed by precipitation of zinc oxide shell and are employed in the photocatalytic disinfection of the model pathogen. Effect of photocatalyst loading and reaction temperature on the disinfection kinetics was studied. Disinfection efficiency in laboratory as well as real water samples was compared with that of pure-ZnO and TiO2 (Degussa P25). Nanocomposite system has shown optimum disinfection (≈98%) at 40-60min of sun-light exposure with a catalyst loading of 0.5mg/L of the reaction solution. The reduction of aquatic bacterial densities by photocatalytically active Ag@ZnO core-shell nanocomposite in presence of natural sun-light may have potential ex situ application in water decontamination at ambient conditions. PMID:25523714

  20. Embeded photonic crystal at the interface of p-GaN and Ag reflector to improve light extraction of GaN-based flip-chip light-emitting diode

    SciTech Connect

    Zhen, Aigong; Ma, Ping Zhang, Yonghui; Guo, Enqing; Tian, Yingdong; Liu, Boting; Guo, Shikuan; Shan, Liang; Wang, Junxi; Li, Jinmin

    2014-12-22

    In this experiment, a flip-chip light-emitting diode with photonic crystal was fabricated at the interface of p-GaN and Ag reflector via nanospheres lithography technique. In this structure, photonic crystal could couple with the guide-light efficiently by reason of the little distance between photonic crystal and active region. The light output power of light emitting diode with embedded photonic crystal was 1.42 times larger than that of planar flip-chip light-emitting diode. Moreover, the embedded photonic crystal structure makes the far-field divergence angle decreased by 18° without spectra shift. The three-dimensional finite difference time domain simulation results show that photonic crystal could improve the light extraction, and enhance the light absorption caused by Ag reflector simultaneously, because of the roughed surface. The depth of photonic crystal is the key parameter affecting the light extraction and absorption. Light extraction efficiency increases with the depth photonic crystal structure rapidly, and reaches the maximum at the depth 80 nm, beyond which light extraction decrease drastically.

  1. Development of Phase-Stable Photon Upconverters for Efficient Solar Energy Utilization

    NASA Astrophysics Data System (ADS)

    Murakami, Yoichi

    Photon upconversion based on triplet-triplet annihilation (TTA) of excited triplet molecules is drawing attention due to its applicability for weak incident light, possessing a potential for improving efficiencies of solar energy conversion devices. Since energy transfer between triplet levels of different molecules and TTA are based on the Dexter mechanism, inter-molecular collision is necessary and hence the majority of previous studies have been done with organic solvents, which are volatile and flammable. This paper presents the development and characterization of phase-stable photon upconverters fabricated with ionic liquids, which are room temperature molten salts with negligible vapor pressure and high thermal stability. The employed aromatic molecules, which are carrier of photo-created energies and are non-polar (or weakly polar) molecules, are found to be stable in the polar environment of ionic liquids, contrary to expectation. The mechanism of the stable solvation is proposed. The upconversion quantum yields are found to rapidly saturate as the excitation light power increases. An analytical model was developed and compared with the experimental data. It is shown that ionic liquids are not viscous media for the purpose of TTA-based upconversion.

  2. Anisotropic emission and photon-recycling in strain-balanced quantum well solar cells

    SciTech Connect

    Cabrera, C. I.; Enciso, A.; Contreras-Solorio, D. A.; Hernandez, L.; Connolly, J. P.

    2014-04-28

    Strain-balanced quantum well solar cells (SB-QWSCs) extend the photon absorption edge beyond that of bulk GaAs by incorporation of quantum wells in the i-region of a p–i–n device. Anisotropy arises from a splitting of the valence band due to compressive strain in the quantum wells, suppressing a transition which contributes to emission from the edge of the quantum wells. We have studied both the emission light polarized in the plane perpendicular (TM) to the quantum well which couples exclusively to the light hole transition and the emission polarized in the plane of the quantum wells (TE) which couples mainly to the heavy hole transition. It was found that the spontaneous emission rates TM and TE increase when the quantum wells are deeper. The addition of a distributed Bragg reflector can substantially increase the photocurrent while decreasing the radiative recombination current. We have examined the impact of the photon recycling effect on SB-QWSC performance. We have optimized SB-QWSC design to achieve single junction efficiencies above 30%.

  3. Novel R2R Manufacturable Photonic-Enhanced Thin Film Solar Cells; January 28, 2010 -- January 31, 2011

    SciTech Connect

    Slafer, D.; Dalal, V.

    2012-03-01

    Final subcontract report for PV Incubator project 'Novel R2R Manufacturable Photonic-Enhanced Thin Film Solar Cells.' The goal of this program was to produce tandem Si cells using photonic bandgap enhancement technology developed at ISU and Lightwave Power that would have an NREL-verified efficiency of 7.5% on 0.25 cm{sup 2} area tandem junction cell on plastic substrates. This goal was met and exceeded within the timeframe and budget of the program. On smaller area cells, the efficiency was even higher, {approx}9.5% (not verified by NREL). Appropriate polymers were developed to fabricate photonic and plasmonic devices on stainless steel, Kapton and PEN substrates. A novel photonic-plasmon structure was developed which shows a promise of improving light absorption in thin film cells, a better light absorption than by any other scheme.

  4. Synthesis and characterization of Zn(O,OH)S and AgInS2 layers to be used in thin film solar cells

    NASA Astrophysics Data System (ADS)

    Vallejo, W.; Arredondo, C. A.; Gordillo, G.

    2010-11-01

    In this paper AgInS2 and Zn(O,OH)S thin films were synthesized and characterized. AgInS2 layers were grown by co-evaporation from metal precursors in a two-step process, and, Zn(O,OH)S thin films were deposited from chemical bath containing thiourea, zinc acetate, sodium citrate and ammonia. X-ray diffraction measurements indicated that AgInS2 thin films grown with chalcopyrite structure, and the as-grown Zn(O,OH)S thin films were polycrystalline. It was also found that the AgInS2 films presented p-type conductivity, a high absorption coefficient (greater than 104 cm-1) and energy band-gap Eg of about 1.95 eV, Zn(O,OH),S thin films presented Eg of about 3.89 eV. Morphological analysis showed that under this synthesis conditions Zn(O,OH),S thin films coated uniformly the absorber layer. Additionally, the Zn(O,OH)S kinetic growth on AgInS2 layer was studied also. Finally, the results suggest that these layers possibly could be used in one-junction solar cells and/or as top cell in a tandem solar cell.

  5. Response of extracellular matrix regulators in mouse lung after exposure to photons, protons and simulated solar particle event protons.

    PubMed

    Tian, Jian; Pecaut, Michael J; Coutrakon, George B; Slater, James M; Gridley, Daila S

    2009-07-01

    This study compared the effects of photons (gamma rays), protons and simulated solar particle event protons (sSPE) on the expression of profibrotic factors/extracellular matrix (ECM) regulators in lung tissue after whole-body irradiation. TGF-beta1, matrix metalloproteinase 2 and 9 (MMP-2, -9), and tissue inhibitor of metalloproteinase 1 and 2 (TIMP-1, -2) were assessed on days 4 and 21 in lungs from C57BL/6 mice exposed to 0 Gy or 2 Gy photons (0.7 Gy/min), protons (0.9 Gy/min) and sSPE (0.056 Gy/h). RT-PCR, histological and immunohistochemical techniques were used. The most striking changes included (1) up-regulation of TGF-beta1 by photons and sSPE, but not protons, at both times, (2) MMP-2 enhancement by photons and sSPEs, (3) TIMP-1 up-regulation by photons at both times, and (4) more collagen accumulation after exposure to either photons or sSPE than after exposure to protons. The findings demonstrate that expression of important ECM regulators was highly dependent upon the radiation regimen as well as the time after exposure. The data further suggest that irradiation during an SPE may increase an astronaut's risk for pulmonary complications. The greater perturbations after photon exposure compared to proton exposure have clinical implications and warrant further investigation. PMID:19580505

  6. Novel Mn3 [Co(CN)6]2@SiO2@Ag Core-Shell Nanocube: Enhanced Two-Photon Fluorescence and Magnetic Resonance Dual-Modal Imaging-Guided Photothermal and Chemo-therapy.

    PubMed

    Wang, Dongdong; Guo, Zhen; Zhou, Jiajia; Chen, Jian; Zhao, Gaozheng; Chen, Ruhui; He, Mengni; Liu, Zhenbang; Wang, Haibao; Chen, Qianwang

    2015-11-25

    The versatile Mn3[Co(CN)6]2@SiO2@Ag core-shell NCs are prepared by a simple coprecipitation method. Ag nanoparticles with an average diameter of 12 nm deposited on the surface of Mn3[Co(CN)6]2@SiO2 through S-Ag bonding are fabricated in ethanol solution by reducing silver nitrate (AgNO3 ) with NaBH4 . The NCs possess T1 -T2 dual-modal magnetic resonance imaging ability. The inner Prussian blue analogs (PBAs) Mn3[Co(CN)6]2 exhibit bright two-photon fluorescence (TPF) imaging when excited at 730 nm. Moreover, the TPF imaging intensity displays 1.85-fold enhancement after loading of Ag nanoparticles. Besides, the sample also has multicolor fluorescence imaging ability under 403, 488, and 543 nm single photon excitation. The as-synthesized Mn3[Co(CN)6]2@SiO2@Ag NCs show a DOX loading capacity of 600 mg g(-1) and exhibit an excellent ability of near-infrared (NIR)-responsive drug release and photothermal therapy (PTT) which is induced from the relative high absorbance in NIR region. The combined chemotherapy and PTT against cancer cells in vitro test shows high therapeutic efficiency. The multimodal treatment and imaging could lead to this material a potential multifunctional system for biomedical diagnosis and therapy. PMID:26437078

  7. Improved solar-driven photocatalytic performance of Ag3PO4/ZnO composites benefiting from enhanced charge separation with a typical Z-scheme mechanism

    NASA Astrophysics Data System (ADS)

    Zhong, Junbo; Li, Jianzhang; Wang, Tao; Zeng, Jun; Si, Yujun; Cheng, Chaozhu; Li, Minjiao; Wang, Pei; Ding, Jie

    2016-01-01

    In this work, efficient simulated solar-driven Ag3PO4/ZnO photocatalysts with different molar ratios of Ag/Zn have been prepared by a precipitation method and characterized by X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy and surface photovoltage (SPV) spectroscopy. Under simulated sunlight illumination, the Ag3PO4/ZnO composites exhibit enhanced photocatalytic activity compared with the pure ZnO toward the decolorization of rhodamine B (RhB) aqueous solution, and the Ag3PO4/ZnO composite with 4 % Ag/Zn molar ratio exhibits the highest activity. The quenching effects of scavengers indicate that O2•- plays the major role in RhB decolorization. Ag3PO4 deposited on the ZnO surface can promote the separation rate of photoinduced charge carriers, proven by the SPV results. Based on all the observations, the charge separation mechanism with a typical Z-scheme was proposed.

  8. GPS as a solar observational instrument: Real-time estimation of EUV photons flux rate during strong, medium, and weak solar flares

    NASA Astrophysics Data System (ADS)

    Singh, Talwinder; Hernandez-Pajares, Manuel; Monte, Enric; Garcia-Rigo, Alberto; Olivares-Pulido, Germán.

    2015-12-01

    In this manuscript, the authors show how the Global Navigation Satellite Systems, GNSS (exemplified in the Global Positioning System, GPS), can be efficiently used for a very different purpose from that for which it was designed as an accurate Solar observational tool, already operational from the open global GPS measurements available in real-time, and with some advantages regarding dedicated instruments onboard spacecraft. The very high correlation of the solar extreme ultraviolet (EUV) photon flux rate in the 26-34 mm spectral band, obtained from the solar EUV monitor instrument onboard the SOHO spacecraft during Solar flares, is shown with the GNSS solar flare activity indicator (GSFLAI). The GSFLAI is defined as the gradient of the ionospheric vertical total electron content rate versus the cosine of the Solar zenith angle in the day hemisphere (which filters out nonsolar over ionization), and it is measured from data collected by a global network of dual frequency GPS receivers (giving in this way continuous coverage). GSFLAI for 60 X class flares, 320 M class flares, and 300 C class flares, occurred since 2001, were directly compared with the EUV solar flux rate data to show existing correlations. It was found that the GSFLAI and EUV flux rate present the same linear relationship for all classes of flares, not only the strong and medium intensity ones, X and M class, as in previous works, but also for the weakest C class solar flares, which is a remarkable result.

  9. Correlations of Optical Absorption, Charge Trapping, and Surface Roughness of TiO2 Photoanode Layer Loaded with Neat Ag-NPs for Efficient Perovskite Solar Cells.

    PubMed

    Yang, Dongwook; Jang, Jae Gyu; Lim, Joohyun; Lee, Jin-Kyu; Kim, Sung Hyun; Hong, Jong-In

    2016-08-24

    We systematically investigated the effect of silver nanoparticles (Ag-NPs) on the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Neat, spherical Ag-NPs at loading levels of 0.0, 0.5, 1.0, and 2.0 wt % were embedded into the titanium dioxide (TiO2) photoanode layer. The plasmonic effect of the Ag-NPs strongly enhanced the incident light absorption over a wide range of the visible wavelength region in addition to the inherent absorbance of the perovskite sensitizer. The low conduction energy level of the Ag-NPs compared to that of TiO2 provides trap sites for free charge carriers. Thus, the correlation between the enhancement of the optical absorption and the number of charge traps provided by the Ag-NPs is critical to determine the device performance, especially current density (Jsc) and PCE. This is confirmed by the quantitative comparison of the incident light absorption and the time-resolved photoluminescence decay according to the loading levels of the Ag-NPs in the TiO2 layer. The absorption enhancement from 380 to 750 nm in the UV-visible spectrum is proportional to the increase in the loading levels of the Ag-NPs. However, the Jsc increases with the device with 0.5 wt % Ag-NPs and gradually decreases with increases in the loading level above 0.5 wt % because of the different contributions to the absorbance and the charge trapping by different Ag-NP loading levels. In addition, the suppression of the surface roughness with dense packing by the Ag-NPs helps to improve the Jsc and the following PCE. Consequently, the PCE of the PSC with 0.5 wt % Ag-NPs is increased to 11.96%. These results are attributed to the balance between increased absorbance by the localized surface plasmon resonance and the decreased charge trapping as well as the decreased surface roughness of the TiO2 layer with the Ag-NPs. PMID:27471777

  10. Multifunctional Ag-decorated porous TiO2 nanofibers in dye-sensitized solar cells: efficient light harvesting, light scattering, and electrolyte contact.

    PubMed

    Hwang, Sun Hye; Song, Hee; Lee, Jungsup; Jang, Jyongsik

    2014-09-26

    Designing the photoanode structure in dye-sensitized solar cells (DSSCs) is vital to realizing enhanced power conversion efficiency (PCE). Herein, novel multifunctional silver-decorated porous titanium dioxide nanofibers (Ag/pTiO2 NFs) made by simple electrospinning, etching, and chemical reduction processes are introduced. The Ag/pTiO2 NFs with a high surface area of 163 m(2)  g(-1) provided sufficient dye adsorption for light harvesting. Moreover, the approximately 200 nm diameter and rough surface of the Ag/pTiO2 NFs offered enough light scattering, and the enlarged interpores among the NFs in the photoanode also permitted electrolyte circulation. Ag nanoparticles (NPs) were well dispersed on the surface of the TiO2 NFs, which prevented aggregation of the Ag NPs after calcination. Furthermore, a localized surface plasmon resonance effect by the Ag NPs served to increase the light absorption at visible wavelengths. The surface area and amount of Ag NPs was optimized. The PCE of pTiO2 NF-based DSSCs was 27 % higher (from 6.2 to 7.9 %) than for pure TiO2 NFs, whereas the PCE of Ag/pTiO2 NF-based DSSCs increased by about 12 % (from 7.9 to 8.8 %). Thus, the PCE of the multifunctional pTiO2 NFs was improved by 42 %, that is, from 6.2 to 8.8 %. PMID:25138442

  11. Light-trapping optimization in wet-etched silicon photonic crystal solar cells

    SciTech Connect

    Eyderman, Sergey; John, Sajeev; Hafez, M.; Al-Ameer, S. S.; Al-Harby, T. S.; Al-Hadeethi, Y.; Bouwes, D. M.

    2015-07-14

    We demonstrate, by numerical solution of Maxwell's equations, near-perfect solar light-trapping and absorption over the 300–1100 nm wavelength band in silicon photonic crystal (PhC) architectures, amenable to fabrication by wet-etching and requiring less than 10 μm (equivalent bulk thickness) of crystalline silicon. These PhC's consist of square lattices of inverted pyramids with sides comprised of various (111) silicon facets and pyramid center-to-center spacing in the range of 1.3–2.5 μm. For a wet-etched slab with overall height H = 10 μm and lattice constant a = 2.5 μm, we find a maximum achievable photo-current density (MAPD) of 42.5 mA/cm{sup 2}, falling not far from 43.5 mA/cm{sup 2}, corresponding to 100% solar absorption in the range of 300–1100 nm. We also demonstrate a MAPD of 37.8 mA/cm{sup 2} for a thinner silicon PhC slab of overall height H = 5 μm and lattice constant a = 1.9 μm. When H is further reduced to 3 μm, the optimal lattice constant for inverted pyramids reduces to a = 1.3 μm and provides the MAPD of 35.5 mA/cm{sup 2}. These wet-etched structures require more than double the volume of silicon, in comparison to the overall mathematically optimum PhC structure (consisting of slanted conical pores), to achieve the same degree of solar absorption. It is suggested these 3–10 μm thick structures are valuable alternatives to currently utilized 300 μm-thick textured solar cells and are suitable for large-scale fabrication by wet-etching.

  12. Displacement damage analysis and modified electrical equivalent circuit for electron and photon-irradiated silicon solar cells

    NASA Astrophysics Data System (ADS)

    Arjhangmehr, Afshin; Feghhi, Seyed Amir Hossein

    2014-10-01

    Solar modules and arrays are the conventional energy resources of space satellites. Outside the earth's atmosphere, solar panels experience abnormal radiation environments and because of incident particles, photovoltaic (PV) parameters degrade. This article tries to analyze the electrical performance of electron and photon-irradiated mono-crystalline silicon (mono-Si) solar cells. PV cells are irradiated by mono-energetic electrons and poly-energetic photons and immediately characterized after the irradiation. The mean degradation of the maximum power (Pmax) of silicon solar cells is presented and correlated using the displacement damage dose (Dd) methodology. This method simplifies evaluation of cell performance in space radiation environments and produces a single characteristic curve for Pmax degradation. Furthermore, complete analysis of the results revealed that the open-circuit voltage (Voc) and the filling factor of mono-Si cells did not significantly change during the irradiation and were independent of the radiation type and fluence. Moreover, a new technique is developed that adapts the irradiation-induced effects in a single-cell equivalent electrical circuit and adjusts its elements. The "modified circuit" is capable of modeling the "radiation damage" in the electrical behavior of mono-Si solar cells and simplifies the designing of the compensation circuits.

  13. Impact of light management on photovoltaic characteristics of GaAs solar cells with photonic crystals and quasi-photonic crystals

    NASA Astrophysics Data System (ADS)

    Lai, Yi-Chun; Yang, Tung-Ting; Yu, Peichen; Hung, Mu-Min; Charlton, Martin

    2014-03-01

    In detailed balance model, the efficiency of single-junction solar cells can be potentially as high as 33.5% under AM 1.5G illumination. However the best state-of-the-art devices are still far lower than those figures, even the electronic quality is nearly perfect. Therefore the efficiency gap should stem from the light management inside solar cells. Recently, external radiation efficiency (ηext) derived from detailed balance model is emphasized to evaluate light management and photon recycling, which aggregates the loss of backward emission into substrate and non-radiative recombination. This factor can be highly relevant to the cell's performance, especially open-circuit voltage (Voc), and maximizing Voc is generally considered as the last mile to approach ultra-high efficiency limit. In this work, we try to quantify the Voc enhancement in GaAs solar cells by enhancing light extraction. The simulation tools are RCWA simulation and photon recycling model NREL developed recently. The top structures we simulate here are TiO2 cones arranged in three PC/QPC lattices. After our calculation, the QPC 12-folds symmetry can make the biggest Voc enhancement 11.21meV compared with bare one, and the structure also possess extraordinary omni-directional anti-reflection ability for maintaining high Jsc. Our results also show that using this way to enhance Voc is especially suitable for cells with ordinary material quality. Therefore, the requests of ideal top structures for solar cells' use are not only near-perfect anti-reflection, but the ability to maximize light extraction if no feature of angular filter exists.

  14. Solar wind test of the de Broglie-Proca massive photon with Cluster multi-spacecraft data

    NASA Astrophysics Data System (ADS)

    Retinò, Alessandro; Spallicci, Alessandro D. A. M.; Vaivads, Andris

    2016-09-01

    Our understanding of the universe at large and small scales relies largely on electromagnetic observations. As photons are the messengers, fundamental physics has a concern in testing their properties, including the absence of mass. We use Cluster four spacecraft data in the solar wind at 1 AU to estimate the mass upper limit for the photon. We look for deviations from Ampère's law, through the curlometer technique for the computation of the magnetic field, and through the measurements of ion and electron velocities for the computation of the current. We show that the upper bound for mγ lies between 1.4 ×10-49 and 3.4 ×10-51  kg, and thereby discuss the currently accepted lower limits in the solar wind.

  15. Solar wind test of the de Broglie-Proca massive photon with Cluster multi-spacecraft data

    NASA Astrophysics Data System (ADS)

    Retinò, Alessandro; Spallicci, Alessandro D. A. M.; Vaivads, Andris

    2016-09-01

    Our understanding of the universe at large and small scales relies largely on electromagnetic observations. As photons are the messengers, fundamental physics has a concern in testing their properties, including the absence of mass. We use Cluster four spacecraft data in the solar wind at 1 AU to estimate the mass upper limit for the photon. We look for deviations from Ampère's law, through the curlometer technique for the computation of the magnetic field, and through the measurements of ion and electron velocities for the computation of the current. We show that the upper bound for mγ lies between 1.4 ×10-49 and 3.4 ×10-51 kg, and thereby discuss the currently accepted lower limits in the solar wind.

  16. Near-uv photon efficiency in a TiO2 electrode - Application to hydrogen production from solar energy

    NASA Technical Reports Server (NTRS)

    Desplat, J.-L.

    1976-01-01

    An n-type (001) TiO2 electrode irradiated at 365 nm was tested under anodic polarization. A saturation current independent of pH and proportional to light intensity has been observed. Accurate measurements of the incident power lead to a 60 per cent photon efficiency. A photoelectrochemical cell built with such an electrode, operated under solar irradiation without concentration, produced an electrolysis current of 0.7 mA/sq cm without applied voltage.

  17. Study of plasmonic nanoparticle arrays for photon management in solar cells

    NASA Astrophysics Data System (ADS)

    Bläsi, Benedikt; Jüchter, Sabrina; Meisenheimer, Sarah-Katharina; Höhn, Oliver; Hauser, Hubert; Wellens, Christine; Fix, Thomas; Schwarz, Ulrich T.

    2014-05-01

    Metallic nanostructures revealing plasmonic effects are a promising approach for improved photon management in thin solar cells. Irregular structures, as found in literature, suffer from parasitic absorption as a result of the varying dimensions of the particles. The parasitic absorption can be minimized by realising regularly ordered particles. Our fabrication process, suitable to meet these requirements, is based on interference lithography (IL), UV nanoimprint lithography (UV-NIL) and lift-off. As a process capable of large area structure origination, we use IL for the realization of master structures. Combining IL with NIL as a replication technique, the process chain is very versatile concerning nanoparticle shapes, sizes and arrangements. In the UV-NIL process, a flexible silicone stamp, which was replicated from the master structure, is pressed into a resist, which is cross-linked by UV light. A plasma etching step is applied to remove the residual resist layer. Afterwards, the substrate is coated with a thin metal layer and finally a lift-off is carried out. This results in metallic nanoparticles arranged in a regular pattern on the substrate. We show simulations and experimental results of round and elliptical disks and half spheres arranged in crossed and hexagonal gratings on glass and silicon. The elliptical particles show polarization dependent resonance effects. In a model assisted parameter study, we demonstrate the influence of various structure parameters on the absorption enhancement in silicon. Finally, optical measurements of ordered silver nanoparticles on the rear side of a silicon wafer are shown.

  18. Boosting Photon Harvesting in Organic Solar Cells with Highly Oriented Molecular Crystals via Graphene-Organic Heterointerface.

    PubMed

    Jo, Sae Byeok; Kim, Hyun Ho; Lee, Hansol; Kang, Boseok; Lee, Seongkyu; Sim, Myungsun; Kim, Min; Lee, Wi Hyoung; Cho, Kilwon

    2015-08-25

    Photon harvesting in organic solar cells is highly dependent on the anisotropic nature of the optoelectronic properties of photoactive materials. Here, we demonstrate an efficient approach to dramatically enhance photon harvesting in planar heterojunction solar cells by using a graphene-organic heterointerface. A large area, residue-free monolayer graphene is inserted at anode interface to serve as an atomically thin epitaxial template for growing highly orientated pentacene crystals with lying-down orientation. This anisotropic orientation enhances the overall optoelectronic properties, including light absorption, charge carrier lifetime, interfacial energetics, and especially the exciton diffusion length. Spectroscopic and crystallographic analysis reveal that the lying-down orientation persists until a thickness of 110 nm, which, along with increased exciton diffusion length up to nearly 100 nm, allows the device optimum thickness to be doubled to yield significantly enhanced light absorption within the photoactive layers. The resultant photovoltaic performance shows simultaneous increment in Voc, Jsc, and FF, and consequently a 5 times increment in the maximum power conversion efficiency than the equivalent devices without a graphene layer. The present findings indicate that controlling organic-graphene heterointerface could provide a design strategy of organic solar cell architecture for boosting photon harvesting. PMID:26166186

  19. Ground-based Photon Path Measurements from Solar Absorption Spectra of the O2 A-band

    NASA Technical Reports Server (NTRS)

    Yang, Z.; Wennberg, P. O.; Cageao, R. P.; Pongetti, T. J.; Toon, G. C.; Sander, S. P.

    2005-01-01

    High-resolution solar absorption spectra obtained from Table Mountain Facility (TMF, 34.38degN, 117.68degW, 2286 m elevation) have been analyzed in the region of the O2 A-band. The photon paths of direct sunlight in clear sky cases are retrieved from the O2 absorption lines and compared with ray-tracing calculations based on the solar zenith angle and surface pressure. At a given zenith angle, the ratios of retrieved to geometrically derived photon paths are highly precise (approx.0.2%), but they vary as the zenith angle changes. This is because current models of the spectral lineshape in this band do not properly account for the significant absorption that exists far from the centers of saturated lines. For example, use of a Voigt function with Lorentzian far wings results in an error in the retrieved photon path of as much as 5%, highly correlated with solar zenith angle. Adopting a super-Lorentz function reduces, but does not completely eliminate this problem. New lab measurements of the lineshape are required to make further progress.

  20. In Situ Photocatalytically Heterostructured ZnO-Ag Nanoparticle Composites as Effective Cathode-Modifying Layers for Air-Processed Polymer Solar Cells.

    PubMed

    Yuan, Kai; Chen, Lie; Chen, Yiwang

    2015-08-10

    A heterostructured semiconductor-metal ZnO-Ag nanoparticle (NP) composite was constructed through a straightforward photocatalytic strategy by using UV irradiation of ZnO NPs and an aqueous solution of Ag precursor. The ZnO-Ag NP composites serve as an effective cathode-modifying layer in polymer solar cells (PSCs) with increased short-circuit current density owing to the light-trapping effect, and improved optical and electrical conductivity properties compared with pure ZnO NPs. The Ag NPs, which are photodeposited in situ on ZnO NPs, can act as effective antennas for incident light to maximize light harvesting and minimize radiative decay or nonradiative losses, consequently resulting in the enhanced photogeneration of excitons in PSCs. Systematic photoelectron and -physical investigations confirm that heterostructured ZnO-Ag NPs can significantly improve charge separation, transport, and collection, as well as lower charge recombination at the cathode interface, leading to a 14.0 % improvement in air-processed device power conversion efficiency. In addition, this processable, cost-effective, and scalable approach is compatible with roll-to-roll manufacturing of large-scale PSCs. PMID:26135916

  1. Design of Ag@C@SnO2@TiO2 yolk-shell nanospheres with enhanced photoelectric properties for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhao, Peilu; Li, Dan; Yao, Shiting; Zhang, Yiqun; Liu, Fengmin; Sun, Peng; Chuai, Xiaohong; Gao, Yuan; Lu, Geyu

    2016-06-01

    The hierarchical Ag@C@SnO2@TiO2 nanospheres (ACSTS) have been successfully synthesized by deposition of SnO2 and TiO2 on the Ag@C templates layer by layer. The size of ACSTS is ca. 360 nm while the Ag@C cores have an average diameter of about 300 nm. The rough and porous shell structure consisting of SnO2 and TiO2 ensures a large specific surface area (115.5 m2 g-1). To demonstrate how such a unique structure might lead to more excellent photovoltaic property, several kinds of dye-sensitized solar cells (DSSCs) are also fabricated using different nanospheres based photoanodes. It is found that the ACSTS based DSSC exhibits an obvious improvement in cell performance. According to various technical characterization, the ACSTS can provide dual-functions of light absorption and charge transfer, hence resulting in an enhanced short-circuit photocurrent density of 18.68 mA cm-2 and a higher FF of 63% compared with other DSSCs. The ACSTS cell finally obtains a PCE of up to 8.62%, increasing by 70.4% and 10.2% than hollow TiO2 nanospheres and Ag@C@TiO2 nanospheres based cells, respectively. The improved photovoltaic properties of ACSTS cell can be mainly ascribed to the unique microstructure and the synergistic effect of the encapsulated Ag@C cores.

  2. Synthesis of Ag-doped TiO2 nanoparticles by combining laser decomposition of titanium isopropoxide and ablation of Ag for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Al-Kamal, Ahmed Kamal

    Nanostructured powders of TiO2 and Ag-doped TiO2 are synthesized by a novel pulsed-laser process that combines laser ablation of a silver (Ag) disc with laser decomposition of a titanium tetra-isopropoxide (TTIP) solution. Nanoparticles are formed by rapid condensation of vaporized species in the plasma plume generated by the high power laser, resulting in the formation of rapidly quenched Ag-doped TiO2 nanoparticles that have far-from-equilibrium or metastable structures. The uniqueness of the new ablation process is that it is a one-step process, in contrast to the two-step process developed by previous researchers in the field. Moreover, its ability to synthesize an extended-solid solution phase of Ag in TiO 2 may also be unique. The present work implies that other oxide phases, such as Al2O3, MgO and MgAl2O4, can be doped with normally insoluble metals, such as Pt and Ir, thus opening new opportunities for catalytic applications. Again, there is the prospect of being able to synthesize nanopowders of diamond, c-BN, and mixtures thereof, which are of interest for applications in machine tools, rock-drill bits, and lightweight armor. A wet-chemistry method is also investigated, which has much in common with that adopted by previous workers in the field. However, photo-voltaic properties do not measure up to expectations based on published data. A possible explanation is that the selected Ag concentrations are too high, so that recombination of holes and electrons occurs via a quantum-tunneling mechanism reduces photo-activity. Future work, therefore, will investigate lower concentrations of Ag dopant in TiO2, while also examining the effects of metastable states, including extended solid solution, amorphous, and semi-crystalline structures.

  3. Aperiodic TiO2 Nanotube Photonic Crystal: Full-Visible-Spectrum Solar Light Harvesting in Photovoltaic Devices

    PubMed Central

    Guo, Min; Xie, Keyu; Wang, Yu; Zhou, Limin; Huang, Haitao

    2014-01-01

    Bandgap engineering of a photonic crystal is highly desirable for photon management in photonic sensors and devices. Aperiodic photonic crystals (APCs) can provide unprecedented opportunities for much more versatile photon management, due to increased degrees of freedom in the design and the unique properties brought about by the aperiodic structures as compared to their periodic counterparts. However, many efforts still remain on conceptual approaches, practical achievements in APCs are rarely reported due to the difficulties in fabrication. Here, we report a simple but highly controllable current-pulse anodization process to design and fabricate TiO2 nanotube APCs. By coupling an APC into the photoanode of a dye-sensitized solar cell, we demonstrate the concept of using APC to achieve nearly full-visible-spectrum light harvesting, as evidenced by both experimental and simulated results. It is anticipated that this work will lead to more fruitful practical applications of APCs in high-efficiency photovoltaics, sensors and optoelectronic devices. PMID:25245854

  4. Set of instruments for solar EUV and soft X-ray monitoring onboard satellite Coronas-Photon

    NASA Astrophysics Data System (ADS)

    Kotov, Yury; Kochemasov, Alexey; Kuzin, Sergey; Kuznetsov, Vladimir; Sylwester, Janusz; Yurov, Vitaly

    Coronas-Photon mission is the third satellite of the Russian Coronas program on solar activity observation. The main goal of the "Coronas-Photon" is the study of solar hard electromagnetic radiation in the wide energy range from UV up to high energy gamma-radiation (2000MeV). Scientific payload for solar radiation observation consists of three types of instruments: Monitors (Natalya-2M, Konus-RF, RT-2, Penguin-M, BRM, PHOKA, Sphin-X, SOKOL spectral and timing measurements of full solar disk radiation have timing in flare/burst mode up to one msec. Instruments Natalya-2M, Konus-RF, RT-2 will cover the wide energy range of hard X-rays and soft gamma-rays (15keV to 2000MeV) and will together constitute the largest area detectors ever used for solar observations. Detectors of gamma-ray monitors are based on structured inorganic scintillators. For X-ray and EUV monitors the scintillation phoswich detectors, gas proportional counter, CdZnTe assembly and filter-covered Si-diodes are used. Telescope-spectrometer TESIS for imaging solar spectroscopy in X-rays has angular resolution up to 1arcsec in three spectral lines. Satellite platform and scientific payload is under construction to be launched in autumn 2008. Satellite orbit is circular with initial height 550km and inclination 82.5degrees. Accuracy of the spacecraft orientation to the Sun is better 3arcmin. In the report the capability of PHOKA, SphinX, SOKOL and TESIS as well as the observation program are described and discussed.

  5. Photonic crystal based on anti-reflection structure for GaN/InGaN heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Ding, Wen; Xia, Deyang; Li, Qiang; Huang, Yaping; Zheng, Min; Zhang, Linzhao; Wang, Jin; Zhang, Ye; Guo, Maofeng; Liu, Shuo; Su, Xilin; Yun, Feng; Hou, Xun

    2015-02-01

    The III-V nitride material such as InGaN has many favorable physical properties including a wide direct band-gap (0.7- 3.4eV), high absorption coefficients (105 cm-1), and high radiation resistance. As such, InGaN has been chosen as an excellent material for full-solar-spectrum photovoltaic applications utilizing its wide and tunable band-gap. The refractive index of GaN is about 2.5 in the full-solar-spectrum. According to the Fresnel formula, there is a high reflection of ~18.4% as the sun light entering GaN. Anti-reflection films could be used on InGaN/GaN solar cell to decrease the reflection loss. The photonic crystal structure is a kind of anti-reflection based on the effective medium theory without any limitations, for example the mismatched thermal expansion coefficient. In this paper, we reported our research work on the design and fabrication of photonic crystal structure on the surface of GaN. FDTD Solutions is used to simulate the reflectivity on the surface of GaN with hexagonal close-packed pillar which has different period-a, diameter-d and height-h. When the parameters a is 500nm, d is 300nm, the reflectivity reached the lowest point of 4.18%. The self-assembly method was used to fabricate the photonic crystal structure on the GaN surface and the fabrication process was also researched. The photonic crystal structures on the surface of p-GaN were obtained and their characteristics of the antireflective film will be discussed in detail.

  6. M-Au/TiO2 (M = Ag, Pd, and Pt) nanophotocatalyst for overall solar water splitting: role of interfaces.

    PubMed

    Melvin, Ambrose A; Illath, Kavya; Das, Tanmay; Raja, Thirumalaiswamy; Bhattacharyya, Somnath; Gopinath, Chinnakonda S

    2015-08-28

    M-Au/TiO2 (M = Ag, Pd, Pt) composites were prepared through a facile one-pot photodeposition synthesis and evaluated for solar water splitting (SWS) with and without a sacrificial agent. The M-Au combination exhibits a dominant role in augmenting the H2 generation activity by forming a bi-metallic system. Degussa P25 was used as a TiO2 substrate to photodeposit Au followed by Au + M (M = Ag/Pd/Pt). The SWS activity of the M-Au/TiO2 was determined through photocatalytic H2 production in the presence of methanol as a sacrificial agent under one sun conditions with an AM1.5 filter. The highest H2 yield was observed for Pt0.5-Au1/TiO2 and was around 1.3 ± 0.07 mmol h(-1) g(-1), with an apparent quantum yield (AQY) of 6.4%. Pt0.5-Au1/TiO2 also demonstrated the same activity for 25 cycles of five hours each for 125 h. Critically, the same Pt0.5-Au1/TiO2 catalyst was active in overall SWS (OSWS) without any sacrificial agent, with an AQY = 0.8%. The amount of Au and/or Pt was varied to obtain the optimum composition and it was found that the Pt0.5-Au1/TiO2 composition exhibits the best activity. Detailed characterization by physico-chemical, spectral and microscopy measurements was carried out to obtain an in-depth understanding of the origin of the photocatalytic activity of Pt0.5-Au1/TiO2. These in-depth studies show that gold interacts predominantly with oxygen vacancies present on titania surfaces, and Pt preferentially interacts with gold for an effective electron-hole pair separation at Pt-Au interfaces and electron storage in metal particles. The Pt in Pt0.5-Au1/TiO2 is electronically and catalytically different from the Pt in Pt/TiO2 and it is predicted that the former suppresses the oxygen reduction reaction. PMID:26199221

  7. Increasing the efficiency of organic solar cells by photonic and electrostatic-field enhancements

    SciTech Connect

    Nalwa, Kanwar

    2011-01-01

    Organic photovoltaic (OPV) technology is an attractive solar-electric conversion paradigm due to the promise of low cost roll-to-roll production and amenability to flexible substrates. Power conversion efficiency (PCE) exceeding 7% has recently been achieved. OPV cells suffer from low charge carrier mobilities of polymers, leading to recombination losses, higher series resistances and lower fill-factors. Thus, it is imperative to develop fabrication methodologies that can enable efficient optical absorption in films thinner than optical absorption length. Active layers conformally deposited on light-trapping, microscale textured, grating-type surfaces is one possible approach to achieve this objective. In this study, 40% theoretical increase in photonic absorption over flat OPVs is shown for devices with textured geometry by the simulation results. For verifying this theoretical result and improving the efficiency of OPVs by light trapping, OPVs were fabricated on grating-type textured substrates possessing t pitch and -coat PV active-layer on these textured substrates led to over filling of the valleys and shunts at the crest, which severely affected the performance of the resultant PV devices. Thus, it is established that although the optical design is important for OPV performance but the potential of light trapping can only be effectively tapped if the textures are amenable for realizing a conformal active layer. It is discovered that if the height of the underlying topographical features is reduced to sub-micron regime (e.g. 300 nm) and the pitch is increased to more than a micron (e.g. 2 μm), the textured surface becomes amenable to coating a conformal PV active-layer. The resultant PV cells showed 100% increase in average light absorption near the band edge due to trapping of higher wavelength photons, and 20% improvement in power conversion efficiency as compared with the flat PV cell. Another factor that severely limits the performance of OPVs is

  8. Simultaneously improving optical absorption of both transverse-electric polarized and transverse-magnetic polarized light for organic solar cells with Ag grating used as transparent electrode

    NASA Astrophysics Data System (ADS)

    Long, Yongbing; Li, Yuanxing; Su, Runmei

    2014-08-01

    Theoretical simulations are performed to investigate optical performance of organic solar cells with Ag grating electrode. It is demonstrated that optical absorption for both transverse-electric (TE) polarized and transverse-magnetic(TM) polarized light is simultaneously improved when compared with that for the device without the Ag grating. The improvement is respectively attributed to the resonance and the surface plasmon polaritons within the device. After an additional WO3 layer is capped on the Ag grating, absorption of TE-polarized light is further improved due to resonance of double microcavities within the device, and absorption of TM-polarized light is improved by the combined effects of the microcavity resonance and the surface plasmon polaritons. Correspondingly, the short current density for randomly polarized light is improved by 18.1% from that of the device without the Ag grating. Finally, it is demonstrated that high transmission may not be an essential prerequisite for metallic gratings when they are used as transparent electrode since absorption loss caused by low transmission can be compensated by using a capping layer to optimize optical resonance of the WMC structure within the device.

  9. Anodic Ag/TiO2 nanotube array formation in NaOH/fluoride/ethylene glycol electrolyte as a photoanode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Nyein, Nyein; Kian Tan, Wai; Kawamura, Go; Matsuda, Astunori; Lockman, Zainovia

    2016-09-01

    Self-organized, 23 μm-thick anodic TiO2 nanotube (TNT) arrays were formed in sodium hydroxide/fluoride/ethylene glycol (EG) electrolyte at 60 V for 60 min. The presence of sodium hydroxide (NaOH) in the fluoride/EG electrolyte accelerates the formation of the TiO2 nanotube arrays. The anodic film was then decorated with silver nanoparticles (Ag NPs) by the photodeposition process and used as a photoanode in a rear-side-illuminated dye-sensitized solar cell. The Ag NPs decorated TNT arrays, with the former having diameters of 10–30 nm formed from 0.2 M of Ag-precursor solution and exhibiting the highest photoconversion efficiency (η) of 3.7% and a short-circuit current density of 12.2 mA cm‑2 compared to η = 3% and short-circuit current density of 9.1 mA cm‑2 for a sample without Ag NPs. The increase in η is thought to be due to the surface plasmon resonance and excess electrons from the nanoparticles.

  10. Anodic Ag/TiO2 nanotube array formation in NaOH/fluoride/ethylene glycol electrolyte as a photoanode for dye-sensitized solar cells.

    PubMed

    Nyein, Nyein; Tan, Wai Kian; Kawamura, Go; Matsuda, Astunori; Lockman, Zainovia

    2016-09-01

    Self-organized, 23 μm-thick anodic TiO2 nanotube (TNT) arrays were formed in sodium hydroxide/fluoride/ethylene glycol (EG) electrolyte at 60 V for 60 min. The presence of sodium hydroxide (NaOH) in the fluoride/EG electrolyte accelerates the formation of the TiO2 nanotube arrays. The anodic film was then decorated with silver nanoparticles (Ag NPs) by the photodeposition process and used as a photoanode in a rear-side-illuminated dye-sensitized solar cell. The Ag NPs decorated TNT arrays, with the former having diameters of 10-30 nm formed from 0.2 M of Ag-precursor solution and exhibiting the highest photoconversion efficiency (η) of 3.7% and a short-circuit current density of 12.2 mA cm(-2) compared to η = 3% and short-circuit current density of 9.1 mA cm(-2) for a sample without Ag NPs. The increase in η is thought to be due to the surface plasmon resonance and excess electrons from the nanoparticles. PMID:27456036

  11. Enhanced efficiencies in thin and semi-transparent dye-sensitized solar cells under low photon flux conditions using TiO2 nanotube photonic crystal

    NASA Astrophysics Data System (ADS)

    Xie, Keyu; Guo, Min; Liu, Xiaolin; Huang, Haitao

    2015-10-01

    The photovoltaic output of dye-sensitized solar cells (DSSCs) are greatly dependent on the amount of absorbed photons, which is limited by the thickness of active layer of DSSCs and the illumination conditions. To improve the cell performance under low irradiance condition, a photoanode was designed by attaching a TiO2 nanotube photonic crystal (NTPC) onto the thin TiO2 nanoparticle (NP) layer for applications in thin and semi-transparent DSSCs. It is found that the introduction of the TiO2 NTPC significantly increases the light harvesting and hence the power conversion efficiency (PCE) of the respective DSSCs. The TiO2 NTPC provides multi-functionalities, such as Bragg reflection, light scatting and additional light harvesting from its nanotube structure, leading to more significant light harvesting enhancement in these thin and semi-transparent DSSCs. Compared with the single-layer TiO2 NP based reference DSSCs, the above-mentioned synergic effects in a cell incoporated with a ∼2.3-μm-thick TiO2 NTPC yield PCE enhancements up to 99.1% and 130%, under 1 and 0.5 Sun conditions, respectively. Meanwhile, an obvious compensation effect of TiO2 NTPC to reduce the output power drop of these cells under tilted incient light is also demonstrated. The work will boost the practical applications of PC in irradiance sensitive devices.

  12. Improved performance of Ag-doped TiO2 synthesized by modified sol-gel method as photoanode of dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Gupta, Arun Kumar; Srivastava, Pankaj; Bahadur, Lal

    2016-08-01

    Ag-doped TiO2 with Ag content ranging from 1 to 7 mol% was synthesized by a modified sol-gel route, and its performance as the photoanode of dye-sensitized solar cells (DSSCs) was compared with undoped TiO2 photoanode. Titanium(IV)isopropoxide was used as precursor and hexamethylenetetramine as the capping agent. XRD results show the formation of TiO2 nanoparticles with an average crystallite size of 5 nm (1 % Ag-doped TiO2) and 9 nm (undoped TiO2), respectively. The TiO2 nanopowder was used to prepare its thin film photoelectrode using doctor's blade method. Significant improvement in light-to-energy conversion efficiency was achieved when thin films of 1 % Ag-doped TiO2 were applied as photoanode in DSSC taking N719 as the sensitizer dye. As evidenced by EIS measurements, the electron lifetime of DSSC with Ag-doped TiO2 increased from 1.33 (for undoped TiO2) to 2.05 ms. The short-circuit current density ( J sc), open-circuit voltage ( V oc), fill factor (FF) and the overall energy conversion efficiency ( η) were 1.07 mA cm-2, 0.72 V, 0.73 and 0.40 %, respectively, with the use of 1 % Ag-doped TiO2 photoanode, whereas with undoped TiO2 under similar conditions, J sc = 0.63 mA cm-2, V oc = 0.70 V, fill factor 0.45 and conversion efficiency 0.14 % could be obtained. Therefore, compared with the reference DSSC containing an undoped TiO2 photoanode, the power conversion efficiency of the cell based on Ag-doped TiO2 has been remarkably enhanced by ~70 %. The substantial improvement in the device performance is attributed to the reduced band-gap energy, retarded charge recombination and greater surface coverage of the sensitizing dye over Ag-doped TiO2, which ultimately resulted in improved IPCE, J SC and η values.

  13. Transfer of Preformed Three-Dimensional Photonic Crystals onto Dye-Sensitized Solar Cells

    SciTech Connect

    Mihi, Agustín; Zhang, Chunjie; Braun, Paul V.

    2011-05-09

    Preformed self-assembled 3D photonic crystals can be infilled with a polycarbonate matrix for mechanical stability and transferred onto rough and porous optoelectronic and photovoltaic devices. This technique allows the incorporation of photonic crystals onto independently processed devices, in which the transferred films have high optical quality.

  14. Observations of solar flare photon energy spectra from 20 keV to 7 MeV

    NASA Technical Reports Server (NTRS)

    Yoshimori, M.; Watanabe, H.; Nitta, N.

    1985-01-01

    Solar flare photon energy spectra in the 20 keV to 7 MeV range are derived from the Apr. 1, Apr. 4, apr. 27 and May 13, 1981 flares. The flares were observed with a hard X-ray and a gamma-ray spectrometers on board the Hinotori satellite. The results show that the spectral shape varies from flare to flare and the spectra harden in energies above about 400 keV. Effects of nuclear line emission on the continuum and of higher energy electron bremsstrahlung are considered to explain the spectral hardening.

  15. Simultaneous Observation of High Temperature Plasma of Solar Corona By TESIS CORONAS-PHOTON and XRT Hinode.

    NASA Astrophysics Data System (ADS)

    Reva, A.; Kuzin, S.; Bogachev, S.; Shestov, S.

    2012-05-01

    The Mg XII spectroheliograph is a part of instrumentation complex TESIS (satellite CORONAS-PHOTON). This instrument builds monochromatic images of hot plasma of the solar corona (λ = 8.42 Å, T>5 MK). The Mg XII spectroheliograph observed hot plasma in the non-flaring active-region NOAA 11019 during nine days. We reconstructed DEM of this active region with the help of genetic algorithm (we used data of the Mg XII spectroheliograph, XRT and EIT). Emission measure of the hot component amounts 1 % of the emission measure of the cool component.

  16. See-through amorphous silicon solar cells with selectively transparent and conducting photonic crystal back reflectors for building integrated photovoltaics

    SciTech Connect

    Yang, Yang; O’Brien, Paul G.; Ozin, Geoffrey A. E-mail: kherani@ecf.utoronto.ca; Kherani, Nazir P. E-mail: kherani@ecf.utoronto.ca

    2013-11-25

    Thin semi-transparent hydrogenated amorphous silicon (a-Si:H) solar cells with selectively transparent and conducting photonic crystal (STCPC) back-reflectors are demonstrated. Short circuit current density of a 135 nm thick a-Si:H cell with a given STCPC back-reflector is enhanced by as much as 23% in comparison to a reference cell with an ITO film functioning as its rear contact. Concurrently, solar irradiance of 295 W/m{sup 2} and illuminance of 3480 lux are transmitted through the cell with a given STCPC back reflector under AM1.5 Global tilt illumination, indicating its utility as a source of space heating and lighting, respectively, in building integrated photovoltaic applications.

  17. Optoelectronic characterization of wide-bandgap (AgCu)(InGa)Se 2 thin-film polycrystalline solar cells including the role of the intrinsic zinc oxide layer

    NASA Astrophysics Data System (ADS)

    Obahiagbon, Uwadiae

    Experiments and simulations were conducted to vary the thickness and the sheet resistance of the high resistance (HR) ZnO layer in polycrystalline thin film (AgCu)(GaIn)Se2 (ACIGS) solar cells. The effect of varying these parameters on the electric field distribution, depletion width and hence capacitance were studied by SCAPS simulation. Devices were then fabricated and characterized by a number of optoelectronic techniques. Thin film CIGS has received a lot of attention, for its use as an absorber layer for thin film solar cells. However, the addition of Silver (Ag) to the CIGS alloy system increases the band gap as indicated from optical transmission measurements and thus higher open circuit voltage (Voc) could be obtained. Furthermore, addition of Ag lowers the melting temperature of the alloy and it is expected that this lowers the defect densities in the absorber and thus leads to higher performance. Transient photocapacitance analysis on ACIGS devices shows sharper band edge indicating lower disorder than CIGS. Presently there is a lack of fundamental knowledge relating film characteristics to device properties and performance. This is due to the fact that some features in the present solar cell structure have been optimized empirically. The goal of this research effort was to develop a fundamental and detailed understanding of the device operation as well as the loss mechanism(s) limiting these devices. Recombination mechanisms in finished ACIGS solar cell devices was studied using advanced admittance techniques (AS, DLCP, CV) to identify electronically active defect state(s) and to study their impact on electronic properties and device performance. Analysis of various optoelectronic measurements of ACIGS solar cells provided useful feedback regarding the impact on device performance of the HR ZnO layer. It was found that thickness between 10-100 nm had negligible impact on performance but reducing the thickness to 0 nm resulted in huge variability in all

  18. Application of heterojunction to Si-based solar cells using photonic nanostructures coupled with vertically aligned Ge quantum dots

    NASA Astrophysics Data System (ADS)

    Takahashi, Isao; Hoshi, Yusuke; Tayagaki, Takeshi; Oikawa, Takafumi; Ohdaira, Keisuke; Usami, Noritaka

    2015-08-01

    We have recently developed a new structure for solar cells that consists of photonic nanostructures coupled with vertically aligned Ge quantum dots on a crystalline Si substrate. For the fabrication of a solar cell device, a heterojunction with a-Si:H was chosen because its processing temperature is less than 200 °C, at which point Ge atoms cannot diffuse into Si layers. In this study, we developed a guideline for the most appropriate cell structures to take advantage of the Ge layer by fabricating heterojunction solar cells with various structures. As a result, we confirmed that the carriers absorbed in Ge quantum dots contributed output current when Ge quantum dots are fabricated on the pn-junction side. Hence, the presence of built-in potential in a Ge dot layer was found to be necessary to extract the carriers generated in the Ge layer. In addition, carrier transport in Ge quantum dots is improved under conditions of reverse bias. Therefore, the electrical field in the Ge layer is a key parameter to improve solar cell performance in our proposed structure.

  19. Enhanced Thermochromic Properties and Solar-Heat Shielding Ability of W(x)V(1-x)O2 Thin Films with Ag Nanowires Capping Layers.

    PubMed

    Zhao, Li Li; Miao, Lei; Liu, Cheng Yan; Wang, Hai Long; Tanemura, Sakae; Sun, Li Xian; Gao, Xiang; Zhou, Jian Hua

    2015-11-01

    Considerable efforts have been made to shift the phase transition temperature of metal-doped vanadium dioxide (VO2) films nearer the ambient temperature while maintain the excellent thermochromic properties simultaneously. Here, we describe a facile and economic solution-based method to fabricate W-doped VO2 (V(1-x)W(x)O2) thin films with excellent thermochromic properties for the application of smart windows. The substitutional doping of tungsten atoms notably reduces the phase transition temperature to the ambient temperature and retains the excellent thermochromic property. Furthermore, Ag nanowires (NWs) are employed as capping layers to effectively decrease the thermal emissivity from 0.833 to 0.603, while the original near infrared region (NIR) modulation ability is not severely affected. Besides, the Ag NWs layers further depress the phase transition temperature as well as the hysteresis loop width, which is important to the fenestration application. These solution-grown Ag NWs/V(1-x)W(x)O2 thin films exhibit excellent solar modulation ability, narrowed hysteresis loop width as well as low thermal emissivity, which provide a promising perspective into the practical application of VO2-based smart windows. PMID:26726666

  20. Electron and photon degradation in aluminum, gallium and boron doped float zone silicon solar cells

    NASA Technical Reports Server (NTRS)

    Rahilly, W. P.; Scott-Monck, J.; Anspaugh, B.; Locker, D.

    1976-01-01

    Solar cells fabricated from Al, Ga and B doped Lopex silicon over a range of resistivities were tested under varying conditions of 1 MeV electron fluence, light exposures and thermal cycling. Results indicate that Al and Ga can replace B as a P type dopant to yield improved solar cell performance.

  1. Back reflectors based on buried Al{sub 2}O{sub 3} for enhancement of photon recycling in monolithic, on-substrate III-V solar cells

    SciTech Connect

    García, I.; Ward, J. S.; Steiner, M. A.; Geisz, J. F.; Kurtz, S. R.

    2014-09-29

    Photon management has been shown to be a fruitful way to boost the open circuit voltage and efficiency of high quality solar cells. Metal or low-index dielectric-based back reflectors can be used to confine the reemitted photons and enhance photon recycling. Gaining access to the back of the solar cell for placing these reflectors implies having to remove the substrate, with the associated added complexity to the solar cell manufacturing. In this work, we analyze the effectiveness of a single-layer reflector placed at the back of on-substrate solar cells, and assess the photon recycling improvement as a function of the refractive index of this layer. Al{sub 2}O{sub 3}-based reflectors, created by lateral oxidation of an AlAs layer, are identified as a feasible choice for on-substrate solar cells, which can produce a V{sub oc} increase of around 65% of the maximum increase attainable with an ideal reflector. The experimental results obtained using prototype GaAs cell structures show a greater than two-fold increase in the external radiative efficiency and a V{sub oc} increase of ∼2% (∼18 mV), consistent with theoretical calculations. For GaAs cells with higher internal luminescence, this V{sub oc} boost is calculated to be up to 4% relative (36 mV), which directly translates into at least 4% higher relative efficiency.

  2. Back reflectors based on buried Al2O3 for enhancement of photon recycling in monolithic, on-substrate III-V solar cells

    NASA Astrophysics Data System (ADS)

    García, I.; Kearns-McCoy, C. F.; Ward, J. S.; Steiner, M. A.; Geisz, J. F.; Kurtz, S. R.

    2014-09-01

    Photon management has been shown to be a fruitful way to boost the open circuit voltage and efficiency of high quality solar cells. Metal or low-index dielectric-based back reflectors can be used to confine the reemitted photons and enhance photon recycling. Gaining access to the back of the solar cell for placing these reflectors implies having to remove the substrate, with the associated added complexity to the solar cell manufacturing. In this work, we analyze the effectiveness of a single-layer reflector placed at the back of on-substrate solar cells, and assess the photon recycling improvement as a function of the refractive index of this layer. Al2O3-based reflectors, created by lateral oxidation of an AlAs layer, are identified as a feasible choice for on-substrate solar cells, which can produce a Voc increase of around 65% of the maximum increase attainable with an ideal reflector. The experimental results obtained using prototype GaAs cell structures show a greater than two-fold increase in the external radiative efficiency and a Voc increase of ˜2% (˜18 mV), consistent with theoretical calculations. For GaAs cells with higher internal luminescence, this Voc boost is calculated to be up to 4% relative (36 mV), which directly translates into at least 4% higher relative efficiency.

  3. Solution-processed highly conductive PEDOT:PSS/AgNW/GO transparent film for efficient organic-Si hybrid solar cells.

    PubMed

    Xu, Qiaojing; Song, Tao; Cui, Wei; Liu, Yuqiang; Xu, Weidong; Lee, Shuit-Tong; Sun, Baoquan

    2015-02-11

    Hybrid solar cells based on n-Si/poly(3,4-ethylenedioxythiophene):poly(styrene- sulfonate) (PEDOT:PSS) heterojunction promise to be a low cost photovoltaic technology by using simple device structure and easy fabrication process. However, due to the low conductivity of PEDOT:PSS, a metal grid deposited by vacuum evaporation method is still required to enhance the charge collection efficiency, which complicates the device fabrication process. Here, a solution-processed graphene oxide (GO)-welded silver nanowires (AgNWs) transparent conductive electrode (TCE) was employed to replace the vacuum deposited metal grid. A unique "sandwich" structure was developed by embedding an AgNW network between PEDOT:PSS and GO with a figure-of-merit of 8.6×10(-3) Ω(-1), which was even higher than that of sputtered indium tin oxide electrode (6.6×10(-3) Ω(-1)). A champion power conversion efficiency of 13.3% was achieved, because of the decreased series resistance of the TCEs as well as the enhanced built-in potential (Vbi) in the hybrid solar cells. The TCEs were obtained by facile low-temperature solution process method, which was compatible with cost-effective mass production technology. PMID:25599588

  4. Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET.

    PubMed

    Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

    2016-04-01

    The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time (τd) and the number of photons detected (n'), i.e. CTR proportional variant √τd/n'. However, it is still an open question to what extent the scintillation rise time (τr) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the single photon time

  5. Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET

    NASA Astrophysics Data System (ADS)

    Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

    2016-04-01

    The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time ({τd} ) and the number of photons detected ({{n}\\prime} ), i.e. CTR\\propto \\sqrt{{τd}/{{n}\\prime}} . However, it is still an open question to what extent the scintillation rise time ({τr} ) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the

  6. Low cost solar array project: Composition measurements by analytical photon catalysis

    NASA Technical Reports Server (NTRS)

    Sutton, D. G.; Galvan, L.; Melzer, J.; Heidner, R. F., III

    1978-01-01

    The applicability of the photon catalysis technique for effecting composition analysis of silicon samples is assessed. In particular, the technique is to be evaluated as a detector for the impurities Al, Cr, Fe, Mn, Ti, V, Mo and Zr. During the first reporting period Al, Cr, Fe and Mn were detected with the photon catalysis method. The best fluorescence lines to monitor and determined initial sensitivities to each of these elements by atomic absorption calibration were established. In the course of these tests, vapor pressure curves for these four pure substances were mapped.

  7. Resolving Ionospheric E-region Modeling Challenges: The Solar Photon Flux Dependence

    NASA Astrophysics Data System (ADS)

    Jensen, Joseph; Sojka, Jan; David, Michael; Tobiska, Kent; Schunk, Robert; Woods, Tom; Eparvier, Frank

    2013-04-01

    The EVE instrument of the NASA Solar Dynamics Observatory (SDO) provides for the first time EUV and XUV measurements of the solar irradiance that adequately define the major source of ionization of the atmosphere. In our study we modeled the E-region of the ionosphere and analyzed how it is affected by the solar irradiance data obtained by EVE and contrast this with the S2000 Solar Irradiance model, used previously. The ionosphere has two major layers, the E-layer at 100 km, and the F-layer at 300 km. The difference in solar irradiances are small except at some wavelength bands, it is these differences that lead to a better understanding of the physical/chemical processes of the E-region. Observations of the ionospheric layers is best achieved using incoherent scatter radars (ISR). We have compared our model with ISR data available from Arecibo Puerto Rico in an effort to understand how specific solar irradiance wavelength bands affect the E-region. This study focuses on two specific wavelength bands 0.1-15 nm and 91-103 nm. Both are responsible for E-region production, but in quite different manners.

  8. Wrinkled silica/titania nanoparticles with tunable interwrinkle distances for efficient utilization of photons in dye-sensitized solar cells.

    PubMed

    Kang, Jin Soo; Lim, Joohyun; Rho, Won-Yeop; Kim, Jin; Moon, Doo-Sik; Jeong, Juwon; Jung, Dongwook; Choi, Jung-Woo; Lee, Jin-Kyu; Sung, Yung-Eun

    2016-01-01

    Efficient light harvesting is essential for the realization of high energy conversion efficiency in dye-sensitized solar cells (DSCs). State-of-the-art mesoporous TiO2 photoanodes fall short for collection of long-wavelength visible light photons, and thus there have been efforts on introduction of scattering nanoparticles. Herein, we report the synthesis of wrinkled silica/titania nanoparticles with tunable interwrinkle distances as scattering materials for enhanced light harvesting in DSCs. These particles with more than 20 times larger specific surface area (>400 m(2)/g) compared to the spherical scattering particles (<20 m(2)/g) of the similar sizes gave rise to the dye-loading amounts, causing significant improvements in photocurrent density and efficiency. Moreover, dependence of spectral scattering properties of wrinkled particles on interwrinkle distances, which was originated from difference in overall refractive indices, was observed. PMID:27488465

  9. Wrinkled silica/titania nanoparticles with tunable interwrinkle distances for efficient utilization of photons in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kang, Jin Soo; Lim, Joohyun; Rho, Won-Yeop; Kim, Jin; Moon, Doo-Sik; Jeong, Juwon; Jung, Dongwook; Choi, Jung-Woo; Lee, Jin-Kyu; Sung, Yung-Eun

    2016-08-01

    Efficient light harvesting is essential for the realization of high energy conversion efficiency in dye-sensitized solar cells (DSCs). State-of-the-art mesoporous TiO2 photoanodes fall short for collection of long-wavelength visible light photons, and thus there have been efforts on introduction of scattering nanoparticles. Herein, we report the synthesis of wrinkled silica/titania nanoparticles with tunable interwrinkle distances as scattering materials for enhanced light harvesting in DSCs. These particles with more than 20 times larger specific surface area (>400 m2/g) compared to the spherical scattering particles (<20 m2/g) of the similar sizes gave rise to the dye-loading amounts, causing significant improvements in photocurrent density and efficiency. Moreover, dependence of spectral scattering properties of wrinkled particles on interwrinkle distances, which was originated from difference in overall refractive indices, was observed.

  10. Wrinkled silica/titania nanoparticles with tunable interwrinkle distances for efficient utilization of photons in dye-sensitized solar cells

    PubMed Central

    Kang, Jin Soo; Lim, Joohyun; Rho, Won-Yeop; Kim, Jin; Moon, Doo-Sik; Jeong, Juwon; Jung, Dongwook; Choi, Jung-Woo; Lee, Jin-Kyu; Sung, Yung-Eun

    2016-01-01

    Efficient light harvesting is essential for the realization of high energy conversion efficiency in dye-sensitized solar cells (DSCs). State-of-the-art mesoporous TiO2 photoanodes fall short for collection of long-wavelength visible light photons, and thus there have been efforts on introduction of scattering nanoparticles. Herein, we report the synthesis of wrinkled silica/titania nanoparticles with tunable interwrinkle distances as scattering materials for enhanced light harvesting in DSCs. These particles with more than 20 times larger specific surface area (>400 m2/g) compared to the spherical scattering particles (<20 m2/g) of the similar sizes gave rise to the dye-loading amounts, causing significant improvements in photocurrent density and efficiency. Moreover, dependence of spectral scattering properties of wrinkled particles on interwrinkle distances, which was originated from difference in overall refractive indices, was observed. PMID:27488465

  11. Influence of some design parameters on the efficiency of solar cells with down-conversion and down shifting of high-energy photons

    NASA Astrophysics Data System (ADS)

    Badescu, Viorel; De Vos, Alexis

    2007-10-01

    In this paper we analyze the system proposed by Trupke et al. [J. Appl. Phys. 92, 1668 (2002)] to increase solar cell efficiency. The system consists of adding to the solar cell a so-called down-converter, which is a device able to convert the high-energy incident photons into photons of lower energy. The contribution consists of taking account (i) the nonradiative recombination in both solar cell and converter, (ii) the refractive index of solar cell and converter materials, and (iii) the solar radiation concentration. Two configurations are studied: the cell and rear converter (C-RC) and front converter and cell (FC-C). The main conclusions of this work are as follow. (1) For ideal down-converters, with radiative recombination only, the solar energy conversion efficiency may be, or may not be, increased by adding a front (or a rear) down-converter to the cell, depending on the value of the solar cell refractive index. (2) More realistic systems, where nonradiative recombinations exist inside the converter, are also considered. The efficiency of the FC-C system is generally less than the efficiency of a single cell. C-RC systems perform better than the cell operating alone for some values of the refractive indices. (3) C-RC systems perform generally better than FC-C systems whatever the values of the refractive indices and the concentration ratio.

  12. Low thermal budget, photonic-cured compact TiO2 layers for high-efficiency perovskite solar cells

    DOE PAGESBeta

    Das, Sanjib; Gu, Gong; Joshi, Pooran C.; Yang, Bin; Aytug, Tolga; Rouleau, Christopher M.; Geohegan, David B.; Xiao, Kai

    2016-05-25

    Rapid advances in organometallic trihalide perovskite solar cells (PSCs) have positioned them to be one of the leading next generation photovoltaic technologies. However, most of the high-performance PSCs, particularly those using compact TiO2 as an electron transport layer, require a high-temperature sintering step, which is not compatible with flexible polymer-based substrates. Considering the materials of interest for PSCs and corresponding device configurations, it is technologically imperative to fabricate high-efficiency cells at low thermal budget so that they can be realized on low-temperature plastic substrates. In this paper, we report on a new photonic curing technique that produces crystalline anatase-phase TiO2more » films on indium tin oxide-coated glass and flexible polyethylene terephthalate (PET) substrates. Finally, the planar PSCs, using photonic-cured TiO2 films, exhibit PCEs as high as 15.0% and 11.2% on glass and flexible PET substrates, respectively, comparable to the device performance of PSCs incorporating furnace annealed TiO2 films.« less

  13. A rare gas optics-free absolute photon flux and energy analyzer for solar and planetary observations

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

    We have developed a prototype spectrometer for space applications requiring long term absolute EUV photon flux measurements. In this recently developed spectrometer, the energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer, followed by an electron multiplier detector, pulses due to individual electrons are counted. The overall efficiency of this process can be made essentially independent of gain drifts in the signal path, and the secular degradation of optical components which is often a problem in other techniques is avoided. A very important feature of this approach is its freedom from the problem of overlapping spectral orders that plagues grating EUV spectrometers. An instrument with these features has not been flown before, but is essential to further advances in our understanding of solar EUV flux dynamics, and the coupled dynamics of terrestrial and planetary atmospheres. The detailed characteristics of this optics-free spectrometer are presented in the publications section.

  14. SnO2-based dye-sensitized hybrid solar cells exhibiting near unity absorbed photon-to-electron conversion efficiency.

    PubMed

    Snaith, Henry J; Ducati, Caterina

    2010-04-14

    Improving the solar light harvesting and photon-to-electron conversion efficiency for hybrid, organic-inorganic photovoltaics are critical challenges. Titania based solid-state hybrid solar cells are moderately efficient at converting visible photons to electrons, but major electrical losses still remain. A material based paradigm shift is required to dramatically enhance the performance of these devices. Here, we present an investigation into solid-state dye-sensitized solar cells (SDSCs) incorporating a molecular hole-transporter and mesoporous tin oxide electrodes, in place of titania usually employed. We investigate the influence of treating the surface of the SnO(2) with different oxides and find that MgO "passivated" SnO(2) electrodes demonstrate an unprecedented absorbed photon-to-electron conversion efficiency of near unity across a broad spectral range. A dual surface treatment of TiO(2) followed by MgO enables tuning of the solar cell photovoltage, fill factor, and efficiency with visible light absorbing cells delivering 3% solar-to-electrical full sun power conversion efficiency. PMID:20302336

  15. 78 FR 2291 - Komax Solar, Inc., a Wholly Owned Subsidiary of Komax Holdings AG, York, PA; Notice of Negative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-10

    ... November 26, 2012 (77 FR 70480). Pursuant to 29 CFR 90.18(c), administrative reconsideration may be granted... the decision. The workers of Komax were engaged in activities related to the production of solar panel... asserted that separations at Komax are attributable to a future shift of solar panel production to...

  16. Thermally Stable Silver Nanowires-Embedding Metal Oxide for Schottky Junction Solar Cells.

    PubMed

    Kim, Hong-Sik; Patel, Malkeshkumar; Park, Hyeong-Ho; Ray, Abhijit; Jeong, Chaehwan; Kim, Joondong

    2016-04-01

    Thermally stable silver nanowires (AgNWs)-embedding metal oxide was applied for Schottky junction solar cells without an intentional doping process in Si. A large scale (100 mm(2)) Schottky solar cell showed a power conversion efficiency of 6.1% under standard illumination, and 8.3% under diffused illumination conditions which is the highest efficiency for AgNWs-involved Schottky junction Si solar cells. Indium-tin-oxide (ITO)-capped AgNWs showed excellent thermal stability with no deformation at 500 °C. The top ITO layer grew in a cylindrical shape along the AgNWs, forming a teardrop shape. The design of ITO/AgNWs/ITO layers is optically beneficial because the AgNWs generate plasmonic photons, due to the AgNWs. Electrical investigations were performed by Mott-Schottky and impedance spectroscopy to reveal the formation of a single space charge region at the interface between Si and AgNWs-embedding ITO layer. We propose a route to design the thermally stable AgNWs for photoelectric device applications with investigation of the optical and electrical aspects. PMID:26971560

  17. Indium tin oxide-free transparent and conductive electrode based on SnO{sub x} | Ag | SnO{sub x} for organic solar cells

    SciTech Connect

    Bou, A.; Torchio, Ph. Barakel, D.; Thierry, F.; Sangar, A.; Thoulon, P.-Y.; Ricci, M.

    2014-07-14

    A SnO{sub x} | Ag | SnO{sub x} multilayer deposited by E-beam evaporation is proposed as transparent anode for a (poly-3-hexylthiophene):[6,6]-phenyl-C{sub 61}-butyric acid methyl ester (P3HT:PCBM) bulk heterojunction based Organic Solar Cell (OSC). Such multilayers are studied and manufactured with the objective to give to the electrode its best conductivity and transparency in the visible spectral range. A transfer matrix method numerical optimization of the thicknesses of each layer of the electrode is developed to limit the number of test samples which would have been manufactured whether an empirical method was chosen. Optical characterization of the deposited SnO{sub x} and Ag thin films is performed to determine the dispersion of the complex refractive indices which are used as input parameters in the model. A satisfying agreement between numerical and experimental optical properties is found. The bare tri-layer electrodes show low sheet resistance (as low as 6.7 Ω/□) and the whole Glass | SnO{sub x} | Ag | SnO{sub x} structure presents a mean transparency on 400–700 nm spectral band as high as 67%. The multilayer is then numerically studied as anode for a P3HT:PCBM bulk heterojunction based OSC. Intrinsic absorption inside the sole active layer is calculated giving the possibility to perform optical optimization on the intrinsic absorption efficiency inside the active area by considering the media embedding the electrodes. An additional study using the morphology of the silver inserted between both oxide layers as input data is performed with a finite difference time domain 3D-method to improve the accordance between optical measurements and numerical results.

  18. Indium tin oxide-free polymer solar cells using a PEDOT : PSS/Ag/PEDOT : PSS multilayer as a transparent anode

    NASA Astrophysics Data System (ADS)

    Yang, Hongsheng; Qu, Bo; Ma, Shengbo; Chen, Zhijian; Xiao, Lixin; Gong, Qihuang

    2012-10-01

    Cost-efficient indium tin oxide (ITO)-free polymer solar cells (PSCs) based on multilayer poly (3,4-ethylene dioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag(15 nm)/PEDOT : PSS (PAP) as the anode were designed and achieved in this work. Compared with the ITO/PEDOT : PSS (IP) and Ag/PEDOT : PSS (AP) layers, the PAP layer showed acceptable optical transparency and electrical conductivity. The average transmittance (350-650 nm) and sheet resistance of PAP were measured to be 50.7% and 2.3 Ω, respectively. In addition, the PAP layer possessed low roughness characterized by atomic force microscopy. In order to investigate the photovoltaic properties of PSCs based on different anodes, devices with the configuration of PAP anode (or IP, AP anode)/poly(3-hexylthiophene) (P3HT) : 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM)/LiF/Al were fabricated. The PAP-based device exhibited reasonable photovoltaic behaviour compared with other devices, and the open-circuit voltage, short-circuit current density, fill factor and power conversion efficiency were calculated to be 0.61 V, 7.01 mA cm-2, 0.69 and 2.99%, respectively. Therefore, PAP was a viable alternative to sputter-grown ITO electrodes, and cost-effective ITO-free PSCs based on a PAP anode could be realized according to this work.

  19. Nanopillar Photovoltaics: Photon Management and Junction Engineering for Next-Generation Solar Cells

    NASA Astrophysics Data System (ADS)

    Mariani, Giacomo

    The sun delivers an amount of energy equivalent to ninety billion hydrogen bombs detonating each second. Despite the fact that only one billionth of that energy falls onto the surface of the Earth, one day of sunlight would be sufficient to power the whole human race energy needs for over half a century. Solar electricity represents an environmentally-benign source of power. However, such technology is still more than twice as expensive as natural gas-fired generators. III-V semiconductor nanopillars are defined as vertically aligned arrays of nanostructures that hold the promise to aggressively diminish the cost of the active photovoltaic cell by exploiting a fraction of material utilized in conventional planar schemes. In this dissertation, we assess the viability of two classes of high-performance nanopillar-based solar cells. We begin with the incorporation of dedicated conjugated polymers to achieve a hybrid organic/inorganic heterojunction. Such configuration introduces a high optical absorption arising from the polymeric layer in conjunction with an efficient carrier transport resulting from the semiconductor nanopillar array. We extend the controllability of the heterojunction properties by replacing traditional spin-casting methods with an electrodeposition technique where the polymer is formed and doped in-situ directly onto the nanopillar facets. The rational tuning of the electrical conductivity and energy level of the polymer translates into an enhanced photocurrent and open-circuit voltage, achieving 4.11% solar power conversion efficiency. We then turn our attention to all-semiconductor radial p-n homojunctions embedded in the nanopillars. The first architecture focuses on ex-situ ammonium-sulfide passivation and correlates the optoelectronic properties of the solar cell once two different types of transparent conducting oxides are adopted. The barrier formed at the contact/semiconductor interface greatly depends on the Hall polarity of the

  20. Low Cost Solar Array Project: Composition Measurements by Analytical Photon Catalysis

    NASA Technical Reports Server (NTRS)

    Sutton, D. G.; Galvan, L.; Melzer, J.; Heidner, R. F., III

    1979-01-01

    The applicability of the photon catalysis technique for effecting composition analysis of silicon samples was assessed. Third quarter activities were devoted to the study of impurities in silicon matrices. The evaporation process was shown to be congruent; thus, the spectral analysis of the vapor yields the composition of the bulk sample. Qualitative analysis of metal impurities in silicon was demonstrated e part per million level. Only one atomic spectral interference was noted; however, it is imperative to maintain a leak tight system due to chemical and spectral interferences caused by the presence of even minute amounts of oxygen in the active nitrogen afterglow.

  1. An Isothermal Device Configuration for Diamond Based Photon-Enhanced Thermionic Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Sun, Tianyin; Koeck, Franz; Nemanich, Robert

    2014-03-01

    Diamond can obtain a negative electron affinity (NEA) after hydrogen termination. With NEA and n-type doping, a low effective work function and efficient thermionic emission has been observed from these diamond films. Photo-induced electron emission from nitrogen doped diamond with visible light illumination has also been established by our group. Recently several reports have described efficient energy conversion based on the photon-enhanced thermionic emission (PETE) mechanism. This study proposes a multi-layer emitter and collector structure for an isothermal PETE converter. The emitter structure is based on an n-type NEA diamond film deposited on a p-type Si substrate to enable electron emission across a vacuum gap. In this structure the above-bandgap light is absorbed in the Si and establishs an enhanced electron population for emission through the low work function surface, while sub-bandgap light is absorbed in the collector for transfer to a heat engine. Spectroscopy measurements of the n-type diamond on Si indicate strong electron emissivity with photon illumination, and the emission intensity is significantly increased at elevated temperatures. A simplified model describing the efficiency and performance of an isothermal PETE device is presented. This research is supported through ONR under grant number # N00014-10-1-0540.

  2. Omnidirectional and broadband optical absorption enhancement in small molecule organic solar cells by a patterned MoO3/Ag/MoO3 transparent anode

    NASA Astrophysics Data System (ADS)

    Tian, Ximin; Hao, Yuying; Zhang, Ye; Cui, Yanxia; Ji, Ting; Wang, Hua; Wei, Bin; Huang, Wei

    2015-03-01

    We designed and calculated a novel organic solar cell (OSC) with MoO3/Ag/MoO3 (MAM) grating as transparent anode and the patterned copper phthalocyanine (CuPc)/fullerence (C60) as active layer. The numerical results indicate that a broadband, omnidirectional light absorption enhancement is realized by utilizing such a one-dimensional (1D) grating with core-shell structure. The total absorption efficiency of the active layer over the wavelength range from 400 to 900 nm is enhanced by 178.88%, 19.44% and 99.16% relative to the equivalent planar cell considering the weight of air-mass 1.5 global (AM 1.5G) solar spectrum at normally incident transverse magnetic (TM), transverse electric (TE) and TM/TE hybrid polarized light, respectively. The improved light trapping is attributed to the multiple modes hybridization of propagating surface plasmon polaritons (SPPs), localized surface plasmons (LSPs) and the strong coupling of SPP waves at TM polarization along with the Floquet modes at TE polarization. Furthermore, the proposed optimized architecture also exhibits an expected short-circuit current density (Jsc) with the value of 11.11 mA/cm2 in theory, which is increased by 116.6% compared with that of the planar control device.

  3. Plasmonic effects in ultrathin amorphous silicon solar cells: performance improvements with Ag nanoparticles on the front, the back, and both.

    PubMed

    Winans, Joshua D; Hungerford, Chanse; Shome, Krishanu; Rothberg, Lewis J; Fauchet, Philippe M

    2015-02-01

    Thin-film hydrogenated amorphous silicon (a-Si:H) solar cells that are free-standing over a 2x2 mm area have been fabricated with thicknesses of 150 nm, 100 nm, and 60 nm. Silver nanoparticles (NPs) created on the front and/or back surfaces of the solar cells led to improvement in performance measures such as current density, overall efficiency, and external quantum efficiency. The effect of changing silver nanoparticle size and incident light angle was tested. Finite-Difference Time-Domain simulations are presented as a way to understand the experimental results as well as guide future research efforts. PMID:25836257

  4. An efficient light trapping scheme based on textured conductive photonic crystal back reflector for performance improvement of amorphous silicon solar cells

    SciTech Connect

    Chen, Peizhuan; Hou, Guofu Huang, Qian; Zhao, Jing; Zhang, Jianjun Ni, Jian; Zhang, Xiaodan; Zhao, Ying; Fan, QiHua

    2014-08-18

    An efficient light trapping scheme named as textured conductive photonic crystal (TCPC) has been proposed and then applied as a back-reflector (BR) in n-i-p hydrogenated amorphous silicon (a-Si:H) solar cell. This TCPC BR combined a flat one-dimensional photonic crystal and a randomly textured surface of chemically etched ZnO:Al. Total efficiency enhancement was obtained thanks to the sufficient conductivity, high reflectivity and strong light scattering of the TCPC BR. Unwanted intrinsic losses of surface plasmon modes are avoided. An initial efficiency of 9.66% for a-Si:H solar cell was obtained with short-circuit current density of 14.74 mA/cm{sup 2}, fill factor of 70.3%, and open-circuit voltage of 0.932 V.

  5. An efficient light trapping scheme based on textured conductive photonic crystal back reflector for performance improvement of amorphous silicon solar cells

    NASA Astrophysics Data System (ADS)

    Chen, Peizhuan; Hou, Guofu; Fan, QiHua; Huang, Qian; Zhao, Jing; Zhang, Jianjun; Ni, Jian; Zhang, Xiaodan; Zhao, Ying

    2014-08-01

    An efficient light trapping scheme named as textured conductive photonic crystal (TCPC) has been proposed and then applied as a back-reflector (BR) in n-i-p hydrogenated amorphous silicon (a-Si:H) solar cell. This TCPC BR combined a flat one-dimensional photonic crystal and a randomly textured surface of chemically etched ZnO:Al. Total efficiency enhancement was obtained thanks to the sufficient conductivity, high reflectivity and strong light scattering of the TCPC BR. Unwanted intrinsic losses of surface plasmon modes are avoided. An initial efficiency of 9.66% for a-Si:H solar cell was obtained with short-circuit current density of 14.74 mA/cm2, fill factor of 70.3%, and open-circuit voltage of 0.932 V.

  6. Highly efficient semitransparent polymer solar cells with color rendering index approaching 100 using one-dimensional photonic crystal.

    PubMed

    Yu, Wenjuan; Jia, Xu; Long, Yongbing; Shen, Liang; Liu, Yan; Guo, Wenbin; Ruan, Shengping

    2015-05-13

    Window application is the important aim for semitransparent solar cells (STPSC) investigation. Here, we demonstrate a method to achieve significantly improved color rendering index (CRI), depressed chromaticity difference (DC), and enhanced power conversion efficiency (PCE) simultaneously by introducing the one-dimensional photonic crystals (1DPCs) Bragg reflector structure onto the STPSC. The device performance is studied from aspects of color perception, electrical properties, and theoretical optical simulations. The STPSCs exhibit achromatic transparency nature color perceptions, especially for the STPSCs with 1DPCs (pairs ≥ 3) under AM 1.5G illumination light source, standard illuminant D65, and standard illuminant A. The excellent CRI is approaching 97 with lower DC about 0.0013 for the device with 5 pairs of 1DPC illumined by AM 1.5G illumination light source. At the same time, the PCE of STPSC devices with 5 pairs of 1DPC was improved from 4.87 ± 0.14% to 5.31 ± 0.13% compared to without. This method provides a facilitative approach to realizing excellent SPTSC window application. PMID:25854166

  7. Photon radiation effects on CdS/CuInSe2 thin film solar cells

    NASA Technical Reports Server (NTRS)

    Dursch, H.; Chen, W.; Rusell, D.

    1985-01-01

    The unknown tolerance of CuInSe2 cells to proton irradiation, was tested. It was shown that CdS/CuInSe2 solar cells have an inherent tolerance to irradiation by 1 MeV electrons up to at least 2 x 10 to the 16th power electrons/sq cm. Eleven, unencapsulated, 1 sq cm cells deposited on alumina substrates were irradiated with 1 MeV protons at normal incidence. The cells were exposed to six fluences ranging from 2.5 x 10 to the 10th power protons/sq cm to 5.0 x 10 to the 13th power protons/sq cm. After each interval of exposure, the cells were removed from the radiation chamber to undergo current/voltage characterization. It is shown that none of the cells electrical characteristics exhibited any degradation up to and including a fluence of 1 x 10 to the 11th power protons/sq cm. At fluences greater than this, the damage to the CuInSe2 cells V sub oc and fill factor (FF) was more severe than that exhibited by the Isc. The CuInSe2 cells proved to be approximately a factor of 50 more resistant to 1 MeV proton irradiation than silicon or gallium arsenide cells. Annealing of a CuInSe2 cell at 225 deg C for 6 minutes restored it to within 95% of its initial efficiency.

  8. Semi-Random Multichromophoric rr-P3HT Analogues for Solar Photon Harvesting

    SciTech Connect

    Burkhart, Beate; Khlyabich, Petr P.; Canak, Tuba Cakir; LaJoie, Travis W.; Thompson, Barry C.

    2011-03-22

    We introduce a new family of semi-random alkylthiophene-based copolymers, which broadly absorb sunlight due to the randomized incorporation of small amounts of acceptors in the polymer backbone. The so-called semi-random structure is defined by a random polymerization that is based on a restricted linkage pattern of the monomers due to regiospecific placement of the reactive functional groups. As a consequence, the polymers are designed to retain a higher degree of structural order than purely random analogues. We have described a family of semi-random donor-acceptor copolymers based on regioregular poly(3-hexylthiophene) (P3HT). In our preliminary investigations, we have found that the attractive properties of P3HT are retained, and despite the randomized polymerization, semicrystalline polymers with high charge carrier mobilities are realized. In addition, broad and intense spectral absorption is achieved with only a limited content (10-17.5%) of acceptor units in the polymer backbone using a simple polymerization method based on easily synthesized monomers. Rigorous optimization of bulk-heterojunction solar cells based on these promising polymers is underway, along with more detailed characterization of the polymer electronic structures and synthesis of tailored structural analogues.

  9. Plasmon-photon conversion to near-infrared emission from Yb3+: (Au/Ag-nanoparticles) in tungsten-tellurite glasses

    NASA Astrophysics Data System (ADS)

    Rivera, V. A. G.; Ledemi, Yannick; Pereira-da-Silva, Marcelo A.; Messaddeq, Younes; Marega, Euclydes, Jr.

    2016-01-01

    This manuscript reports on the interaction between 2F5/2→2F7/2 radiative transition from Yb3+ ions and localized surface plasmon resonance (from gold/silver nanoparticles) in a tungsten-tellurite glass. Such an interaction, similar to the down-conversion process, results in the Yb3+ emission in the near-infrared region via resonant and non-resonant energy transfers. We associated such effects with the dynamic coupling described by the variations generated by the Hamiltonian HDC in either the oscillator strength, or the local crystal field, i.e. the line shape changes in the emission band. Here, the Yb3+ ions emission is achieved through plasmon-photon coupling, observable as an enhancement or quenching in the luminescence spectra. Metallic nanoparticles have light-collecting capability in the visible spectrum and can accumulate almost all the photon energy on a nanoscale, which enable the excitation and emission of the Yb3+ ions in the near-infrared region. This plasmon-photon conversion was evaluated from the cavity’s quality factor (Q) and the coupling (g) between the nanoparticles and the Yb3+ ions. We have found samples of low-quality cavities and strong coupling between the nanoparticles and the Yb3+ ions. Our research can be extended towards the understanding of new plasmon-photon converters obtained from interactions between rare-earth ions and localized surface plasmon resonance.

  10. Plasmon-photon conversion to near-infrared emission from Yb3+: (Au/Ag-nanoparticles) in tungsten-tellurite glasses

    PubMed Central

    Rivera, V. A. G.; Ledemi, Yannick; Pereira-da-Silva, Marcelo A.; Messaddeq, Younes; Marega Jr, Euclydes

    2016-01-01

    This manuscript reports on the interaction between 2F5/2→2F7/2 radiative transition from Yb3+ ions and localized surface plasmon resonance (from gold/silver nanoparticles) in a tungsten-tellurite glass. Such an interaction, similar to the down-conversion process, results in the Yb3+ emission in the near-infrared region via resonant and non-resonant energy transfers. We associated such effects with the dynamic coupling described by the variations generated by the Hamiltonian HDC in either the oscillator strength, or the local crystal field, i.e. the line shape changes in the emission band. Here, the Yb3+ ions emission is achieved through plasmon-photon coupling, observable as an enhancement or quenching in the luminescence spectra. Metallic nanoparticles have light-collecting capability in the visible spectrum and can accumulate almost all the photon energy on a nanoscale, which enable the excitation and emission of the Yb3+ ions in the near-infrared region. This plasmon-photon conversion was evaluated from the cavity’s quality factor (Q) and the coupling (g) between the nanoparticles and the Yb3+ ions. We have found samples of low-quality cavities and strong coupling between the nanoparticles and the Yb3+ ions. Our research can be extended towards the understanding of new plasmon-photon converters obtained from interactions between rare-earth ions and localized surface plasmon resonance. PMID:26725938

  11. Plasmon-photon conversion to near-infrared emission from Yb(3+): (Au/Ag-nanoparticles) in tungsten-tellurite glasses.

    PubMed

    Rivera, V A G; Ledemi, Yannick; Pereira-da-Silva, Marcelo A; Messaddeq, Younes; Marega, Euclydes

    2016-01-01

    This manuscript reports on the interaction between (2)F5/2→(2)F7/2 radiative transition from Yb(3+) ions and localized surface plasmon resonance (from gold/silver nanoparticles) in a tungsten-tellurite glass. Such an interaction, similar to the down-conversion process, results in the Yb(3+) emission in the near-infrared region via resonant and non-resonant energy transfers. We associated such effects with the dynamic coupling described by the variations generated by the Hamiltonian HDC in either the oscillator strength, or the local crystal field, i.e. the line shape changes in the emission band. Here, the Yb(3+) ions emission is achieved through plasmon-photon coupling, observable as an enhancement or quenching in the luminescence spectra. Metallic nanoparticles have light-collecting capability in the visible spectrum and can accumulate almost all the photon energy on a nanoscale, which enable the excitation and emission of the Yb(3+) ions in the near-infrared region. This plasmon-photon conversion was evaluated from the cavity's quality factor (Q) and the coupling (g) between the nanoparticles and the Yb(3+) ions. We have found samples of low-quality cavities and strong coupling between the nanoparticles and the Yb(3+) ions. Our research can be extended towards the understanding of new plasmon-photon converters obtained from interactions between rare-earth ions and localized surface plasmon resonance. PMID:26725938

  12. Radiation exposure due to cosmic rays and solar X-ray photons at various atmospheric heights in aviation range over India

    NASA Astrophysics Data System (ADS)

    Palit, Sourav; Chakrabarti, Sandip Kumar; Bhattacharya, Arnab

    2016-07-01

    In this presentation we present our work on the continuous monitoring of radiation exposure in terms of effective dose rates, due to galactic cosmic rays (GCR) and solar X-rays at various altitudes within aviation range over India. As India belongs to equatorial region, there is negligible contribution from solar energetic particles (SEP). The calculation of cosmic ray counts as well as the solar X-ray photons are performed on the basis of the observation of various Dignity series balloon experiments on cosmic ray and solar high energy radiation studies, conducted by ICSP and Monte Carlo simulations performed with GEANT4 detector simulation software. The information on solar activity level from Geostationary Operational Environmental Satellite system (GOES) are employed in the calculations. A program, which is done entirely in MATLAB is employed to update regularly in a website, where we show images of dose rate (μSv) distribution over India at four different heights within the aviation range (updating at an interval of 30 minutes) and the approximate dose rates thats should be experienced by a pilot in an entire flight time between pairs of stations distributed all over India.

  13. Anomalous photoelectric emission from Ag on zinc-phthalocyanine film

    NASA Astrophysics Data System (ADS)

    Tanaka, Senku; Otani, Tomohiro; Fukuzawa, Ken; Ogawa, Koji; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao; Hiromitsu, Ichiro

    2014-05-01

    Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4 eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4 eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1 nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles.

  14. Anomalous photoelectric emission from Ag on zinc-phthalocyanine film

    SciTech Connect

    Tanaka, Senku; Otani, Tomohiro; Fukuzawa, Ken; Hiromitsu, Ichiro; Ogawa, Koji; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao

    2014-05-12

    Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4 eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4 eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1 nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles.

  15. Study of non-thermal photon production under different scenarios in solar flares. 2: The Compton inverse and Bremsstrahlung models and fittings

    NASA Technical Reports Server (NTRS)

    Perez-Peraza, J.; Alvarez, M.; Laville, A.; Gallegos, A.

    1985-01-01

    Energy spectra of photons emitted from Bremsstrahlung (BR) of energetic electrons with matter, is obtained from the deconvolution of the electron energy spectra. It can be inferred that the scenario for the production of X-rays and gamma rays in solar flares may vary from event to event. However, it is possible in many cases to associated low energy events to impulsive acceleration, and the high energy phase of some events to stochastic acceleration. In both cases, flare particles seem to be strongly modulated by local energy losses. Electric field acceleration, associated to neutral current sheets is a suitable candidate for impulsive acceleration. Finally, that the predominant radiation process of this radiation is the inverse Compton effect due to the local flare photon field.

  16. ZnO@Ag2S core-shell nanowire arrays for environmentally friendly solid-state quantum dot-sensitized solar cells with panchromatic light capture and enhanced electron collection.

    PubMed

    Zhang, Xiaoliang; Liu, Jianhua; Zhang, Jindan; Vlachopoulos, Nick; Johansson, Erik M J

    2015-05-21

    A solid-state environmentally friendly Ag2S quantum dot-sensitized solar cell (QDSSC) is demonstrated. The photovoltaic device is fabricated by applying ZnO@Ag2S core-shell nanowire arrays (NWAs) as light absorbers and electron conductors, and poly-3-hexylthiophene (P3HT) as a solid-state hole conductor. Ag2S quantum dots (QDs) were directly grown on the ZnO nanowires by the successive ionic layer adsorption and reaction (SILAR) method to obtain the core-shell nanostructure. The number of SILAR cycles for QD formation and the length of the core-shell NWs significantly affect the photocurrent. The device with a core-shell NWAs photoanode shows a power conversion efficiency increase by 32% compared with the device based on a typical nanoparticle-based photoanode with Ag2S QDs. The enhanced performance is attributed to enhanced collection of the photogenerated electrons utilizing the ZnO nanowire as an efficient pathway for transporting the photogenerated electrons from the QD to the contact. PMID:25907247

  17. Broadband and Low-Loss Plasmonic Light Trapping in Dye-Sensitized Solar Cells Using Micrometer-Scale Rodlike and Spherical Core-Shell Plasmonic Particles.

    PubMed

    Malekshahi Byranvand, Mahdi; Nemati Kharat, Ali; Taghavinia, Nima; Dabirian, Ali

    2016-06-29

    Dielectric scattering particles have widely been used as embedded scattering elements in dye-sensitized solar cells (DSCs) to improve the optical absorption of the device. Here we systematically study rodlike and spherical core-shell silica@Ag particles as more effective alternatives to the dielectric scattering particles. The wavelength-scale silica@Ag particles with sufficiently thin Ag shell support hybrid plasmonic-photonic resonance modes that have low parasitic absorption losses and a broadband optical response. Both of these features lead to their successful deployment in light trapping in high-efficiency DSCs. Optimized rodlike silica@Ag@silica particles improve the power conversion efficiency of a DSC from 6.33 to 8.91%. The dimension, surface morphology, and concentration of these particles are optimized to achieve maximal efficiency enhancement. The rodlike silica particles are prepared in a simple one-pot synthesis process and then are coated with Ag in a liquid-phase deposition process by reducing an Ag salt. The aspect ratio of silica rods is tuned by adjusting the temperature and duration of the growth process, whereas the morphology of Ag shell is tailored by controlling the reduction rate of Ag salt, where slower reduction in a polyol process gives a smoother Ag shell. Using optical calculations, the superior performance of the plasmonic core-shell particles is related to the large number of hybrid photonic-plasmonic resonance modes that they support. PMID:27300764

  18. Photonic light-trapping versus Lambertian limits in thin film silicon solar cells with 1D and 2D periodic patterns.

    PubMed

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

    2012-03-12

    We theoretically investigate the light-trapping properties of one- and two-dimensional periodic patterns etched on the front surface of c-Si and a-Si thin film solar cells with a silver back reflector and an anti-reflection coating. For each active material and configuration, absorbance A and short-circuit current density Jsc are calculated by means of rigorous coupled wave analysis (RCWA), for different active materials thicknesses in the range of interest of thin film solar cells and in a wide range of geometrical parameters. The results are then compared with Lambertian limits to light-trapping for the case of zero absorption and for the general case of finite absorption in the active material. With a proper optimization, patterns can give substantial absorption enhancement, especially for 2D patterns and for thinner cells. The effects of the photonic patterns on light harvesting are investigated from the optical spectra of the optimized configurations. We focus on the main physical effects of patterning, namely a reduction of reflection losses (better impedance matching conditions), diffraction of light in air or inside the cell, and coupling of incident radiation into quasi-guided optical modes of the structure, which is characteristic of photonic light-trapping. PMID:22418672

  19. Coupled experimetal and theoretical study of photon absorption and charge transport in BiVO4 photoanodes for solar water splitting

    NASA Astrophysics Data System (ADS)

    Ping, Yuan; Kim, Tae Woo; Galli, Giulia; Choi, Kyoung-Shin

    Bismuth vanadate (BiVO4) has been identified as one of the most promising photoanode materials for water-splitting photoelectrochemical cells. The major limitations of BiVO4 are its relatively wide bandgap (2.5 eV) and low electron mobility (0.2 cm-2V-2S-1), which limit its solar-to-hydrogen conversion efficiency. In this talk we will present the results of a coupled experimental and ab initio theoretical study showing that nitrogen doping together with extra oxygen vacancies lead to both a reduction of BiVO4 band gap and to an increase of the majority carrier density and mobility. In turn these improvements lead to the applied bias photon-to-current efficiency over 2%, a record for a single oxide photon absorber, to the best of our knowledge. The ``codoping'' method adopted in our work could also be applied to simultaneously enhance photon absorption and charge transport in other oxides, providing new possibilities for photocatalytic materials. This work was supported by the National Science Foundation (NSF) under the NSF Center (CHE-1305124). Computer time was provided by NERSC.

  20. Double-shelled plasmonic Ag-TiO2 hollow spheres toward visible light-active photocatalytic conversion of CO2 into solar fuel

    NASA Astrophysics Data System (ADS)

    Feng, Shichao; Wang, Meng; Zhou, Yong; Li, Ping; Tu, Wenguang; Zou, Zhigang

    2015-10-01

    Double-shelled hollow hybrid spheres consisting of plasmonic Ag and TiO2 nanoparticles were successfully synthesized through a simple reaction process. The analysis reveals that Ag nanoparticles were dispersed uniformly in the TiO2 nanoparticle shell. The plasmonic Ag-TiO2 hollow sphere proves to greatly enhance the photocatalytic activity toward reduction of CO2 into renewable hydrocarbon fuel (CH4) in the presence of water vapor under visible-light irradiation. The possible formation mechanism of the hollow sphere and related plasmon-enhanced photocatalytic performance were also briefly discussed.

  1. Double-shelled plasmonic Ag-TiO{sub 2} hollow spheres toward visible light-active photocatalytic conversion of CO{sub 2} into solar fuel

    SciTech Connect

    Feng, Shichao; Wang, Meng; Li, Ping; Tu, Wenguang; Zhou, Yong; Zou, Zhigang

    2015-10-01

    Double-shelled hollow hybrid spheres consisting of plasmonic Ag and TiO{sub 2} nanoparticles were successfully synthesized through a simple reaction process. The analysis reveals that Ag nanoparticles were dispersed uniformly in the TiO{sub 2} nanoparticle shell. The plasmonic Ag-TiO{sub 2} hollow sphere proves to greatly enhance the photocatalytic activity toward reduction of CO{sub 2} into renewable hydrocarbon fuel (CH{sub 4}) in the presence of water vapor under visible-light irradiation. The possible formation mechanism of the hollow sphere and related plasmon-enhanced photocatalytic performance were also briefly discussed.

  2. One-pot synthesis of Ag/r-GO/TiO2 nanocomposites with high solar absorption and enhanced anti-recombination in photocatalytic applications.

    PubMed

    Gao, Weiyin; Wang, Minqiang; Ran, Chenxin; Yao, Xi; Yang, Honghui; Liu, Jing; He, Delong; Bai, Jinbo

    2014-05-21

    In this paper, we reported a simple one-pot solvothermal approach to fabricate Ag/reduced graphene oxide (r-GO)/TiO2 composite photocatalyst under atmospheric pressure. Based on the experimental data, we concluded that the introduction of Ag into classical graphene-TiO2 system (i) efficiently enlarges the absorption range, (ii) improves photogenerated electron separation and (iii) increases photocatalysis reaction sites. The optimized sample exhibits prominent photocatalysis ability as compared to pure TiO2 under simulated sunlight. We further proposed that besides the above three advantages of Ag, a different size of Ag nanoparticles is also responsible for the improved photocatalysis ability, where small size Ag nanoparticles (2-5 nm) could store a photoexcited electron that was generated from TiO2, while large-size Ag nanoparticles could utilize visible light due to their localized surface plasmon resonance (LSPR) absorption. Our present work gives new insights into the photocatalysis mechanism of noble metal/r-GO/TiO2 composites and provides a new pathway into the design of TiO2-based photocatalysts and promote their practical application in various environmental and energy issues. PMID:24730025

  3. One-pot synthesis of Ag/r-GO/TiO2 nanocomposites with high solar absorption and enhanced anti-recombination in photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Gao, Weiyin; Wang, Minqiang; Ran, Chenxin; Yao, Xi; Yang, Honghui; Liu, Jing; He, Delong; Bai, Jinbo

    2014-04-01

    In this paper, we reported a simple one-pot solvothermal approach to fabricate Ag/reduced graphene oxide (r-GO)/TiO2 composite photocatalyst under atmospheric pressure. Based on the experimental data, we concluded that the introduction of Ag into classical graphene-TiO2 system (i) efficiently enlarges the absorption range, (ii) improves photogenerated electron separation and (iii) increases photocatalysis reaction sites. The optimized sample exhibits prominent photocatalysis ability as compared to pure TiO2 under simulated sunlight. We further proposed that besides the above three advantages of Ag, a different size of Ag nanoparticles is also responsible for the improved photocatalysis ability, where small size Ag nanoparticles (2-5 nm) could store a photoexcited electron that was generated from TiO2, while large-size Ag nanoparticles could utilize visible light due to their localized surface plasmon resonance (LSPR) absorption. Our present work gives new insights into the photocatalysis mechanism of noble metal/r-GO/TiO2 composites and provides a new pathway into the design of TiO2-based photocatalysts and promote their practical application in various environmental and energy issues.In this paper, we reported a simple one-pot solvothermal approach to fabricate Ag/reduced graphene oxide (r-GO)/TiO2 composite photocatalyst under atmospheric pressure. Based on the experimental data, we concluded that the introduction of Ag into classical graphene-TiO2 system (i) efficiently enlarges the absorption range, (ii) improves photogenerated electron separation and (iii) increases photocatalysis reaction sites. The optimized sample exhibits prominent photocatalysis ability as compared to pure TiO2 under simulated sunlight. We further proposed that besides the above three advantages of Ag, a different size of Ag nanoparticles is also responsible for the improved photocatalysis ability, where small size Ag nanoparticles (2-5 nm) could store a photoexcited electron that was

  4. Spectrally resolved intraband transitions on two-step photon absorption in InGaAs/GaAs quantum dot solar cell

    SciTech Connect

    Tamaki, Ryo Shoji, Yasushi; Okada, Yoshitaka; Miyano, Kenjiro

    2014-08-18

    Two-step photon absorption processes in a self-organized In{sub 0.4}Ga{sub 0.6}As/GaAs quantum dot (QD) solar cell have been investigated by monitoring the mid-infrared (IR) photoinduced modulation of the external quantum efficiency (ΔEQE) at low temperature. The first step interband and the second step intraband transitions were both spectrally resolved by scanning photon energies of visible to near-IR CW light and mid-IR pulse lasers, respectively. A peak centered at 0.20 eV corresponding to the transition to virtual bound states and a band above 0.42 eV probably due to photoexcitation to GaAs continuum states were observed in ΔEQE spectra, when the interband transition was above 1.4 eV, directly exciting wetting layers or GaAs spacer layers. On the other hand, resonant excitation of the ground state of QDs at 1.35 eV resulted in a reduction of EQE. The sign of ΔEQE below 1.40 eV changed from negative to positive by increasing the excitation intensity of the interband transition. We ascribe this to the filling of higher energy trap states.

  5. Effects of solar ultraviolet photons on mammalian cell DNA. [UVA (320-400 nm):a2

    SciTech Connect

    Peak, M.J.; Peak, J.G.

    1991-01-01

    This document presents information on the possible mechanisms of carcinogenesis caused by UVA (ultraviolet radiation in the 320--400 nm region). Most studies showing the carcinogenic effects of ultraviolet light have concentrated on UVB (280--320 nm). UVA had been considered harmless even though it penetrates biological tissues better than UVB. Recently, it has become apparent that UVA is also capable of causing damage to cellular DNA. This was unexpected because the DNA UV absorption spectrum indicates a negligible probability that photons of wavelengths longer than 320 nm will be directly absorbed. The most common defects induced in DNA by UVB are pyrimidine photoproducts, such as thymidine dimers. UVA photons produce defects resembling those caused by ionizing radiations: single- and double-strand breaks, and DNA-protein crosslinks. This paper also discusses the role of DNA repair mechanisms in UVA-induced defects and the molecular mechanisms of UVA damage induction. 38 refs. (MHB)

  6. Improved conversion efficiency of Ag2S quantum dot-sensitized solar cells based on TiO2 nanotubes with a ZnO recombination barrier layer

    PubMed Central

    2011-01-01

    We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO2 nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO2 nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electrodes, with increasing the cycles of Ag2S deposition, the photocurrent density and the conversion efficiency increase. In addition, as compared to the Ag2S QD-sensitized TiO2 nanotube-array electrode without the ZnO layers, the conversion efficiency of the electrode with the ZnO layers increases significantly due to the formation of efficient recombination layer between the TiO2 nanotube array and electrolyte. PMID:21777458

  7. Exceeding the solar cell Shockley-Queisser limit via thermal up-conversion of low-energy photons

    NASA Astrophysics Data System (ADS)

    Boriskina, Svetlana V.; Chen, Gang

    2014-03-01

    Maximum efficiency of ideal single-junction photovoltaic (PV) cells is limited to 33% (for 1 sun illumination) by intrinsic losses such as band edge thermalization, radiative recombination, and inability to absorb below-bandgap photons. This intrinsic thermodynamic limit, named after Shockley and Queisser (S-Q), can be exceeded by utilizing low-energy photons either via their electronic up-conversion or via the thermophotovoltaic (TPV) conversion process. However, electronic up-conversion systems have extremely low efficiencies, and practical temperature considerations limit the operation of TPV converters to the narrow-gap PV cells. Here we develop a conceptual design of a hybrid TPV platform, which exploits thermal up-conversion of low-energy photons and is compatible with conventional silicon PV cells by using spectral and directional selectivity of the up-converter. The hybrid platform offers sunlight-to-electricity conversion efficiency exceeding that imposed by the S-Q limit on the corresponding PV cells across a broad range of bandgap energies, under low optical concentration (1-300 suns), operating temperatures in the range 900-1700 K, and in simple flat panel designs. We demonstrate maximum conversion efficiency of 73% under illumination by non-concentrated sunlight. A detailed analysis of non-ideal hybrid platforms that allows for up to 15% of absorption/re-emission losses yields limiting efficiency value of 45% for Si PV cells.

  8. AGS II

    SciTech Connect

    Palmer, R.B.

    1984-01-01

    Interest in rare K decays, neutrino oscillations and other fields have generated an increasing demand for running, and improved intensity and duty cycle, at the AGS. Current projects include acceleration of polarized protons and light ions (up to mass 32). Future plans are for a booster to increase intensity and allow heavy ions (up to mass 200), and a stretcher to give 100% duty cycle. A later upgrade could yield an average current of 32 ..mu.. amps. 6 figures, 2 tables.

  9. Photon-photon collisions

    SciTech Connect

    Burke, D.L.

    1982-10-01

    Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.

  10. Enhanced performance of dye-sensitized solar cells via plasmonic sandwiched structure

    NASA Astrophysics Data System (ADS)

    Lin, Su-Jien; Lee, Kuang-Che; Wu, Jyun-Lin; Wu, Jun-Yi

    2011-07-01

    The plasmonic structure of sandwiched TiO2/NPs-Ag/TiO2 electrodes was fabricated by sputter technology and sol-gel and spin coating procedure to enhance the performance of dye-sensitized solar cells. The improvement of the incident photon to photocurrent efficiency spectrum corresponding to the strong absorption and damping reflection indicated light trapping of plasmonic structure to elongate the optical pathways of photons. More light trapped close to photocurrent collecting electrode provides better charge-collection and light harvesting efficiencies. As a result of improved dye absorption, about 23% enhancement in photocurrent density has been achieved.

  11. Increasing photon absorption and stability of PbS quantum dot solar cells using a ZnO interlayer

    SciTech Connect

    Lai, Lai-Hung; Speirs, Mark J.; Loi, Maria A.; Chang, Feng-Kuei; Chen, Jen-Sue; Piveteau, Laura; Kovalenko, Maksym V.; Wu, Jih-Jen

    2015-11-02

    We compared PbS quantum dot (QD) solar cells with different cathode interlayer materials, namely, LiF and ZnO nanoparticles, using the same device structure. Solar cells fabricated with the ZnO interlayer gave a power conversion efficiency of 4.8%, which is higher (above the experimental variation) than the 4.1% efficiency obtained with a LiF interlayer. We found that the ZnO interlayer alters the spatial distribution of the optical field, leading to an increase in external quantum efficiency in the visible range. Furthermore, devices with ZnO as interlayer showed more stable performance than the ones using LiF, with practically no power conversion efficiency degradation after 1 month inside a N{sub 2} glovebox.

  12. A hot-electron thermophotonic solar cell demonstrated by thermal up-conversion of sub-bandgap photons

    PubMed Central

    Farrell, Daniel J.; Sodabanlu, Hassanet; Wang, Yunpeng; Sugiyama, Masakazu; Okada, Yoshitaka

    2015-01-01

    The direct conversion of solar energy to electricity can be broadly separated into two main categories: photovoltaics and thermal photovoltaics, where the former utilizes gradients in electrical potential and the latter thermal gradients. Conventional thermal photovoltaics has a high theoretical efficiency limit (84%) but in practice cannot be easily miniaturized and is limited by the engineering challenges of sustaining large (>1,000 K) temperature gradients. Here we show a hot-carrier-based thermophotonic solar cell, which combines the compact nature of photovoltaic devices with the potential to reach the high-efficiency regime of thermal photovoltaics. In the device, a thermal gradient of 500 K is established by hot electrons, under Stokes illumination, rather than by raising the temperature of the material itself. Under anti-Stokes (sub-bandgap) illumination we observe a thermal gradient of ∼20 K, which is maintained by steady-state Auger heating of carriers and corresponds to a internal thermal up-conversion efficiency of 30% between the collector and solar cell. PMID:26541415

  13. UV to NIR photon conversion in Nd-doped rutile and anatase titanium dioxide films for silicon solar cell application

    NASA Astrophysics Data System (ADS)

    Le Boulbar, E.; Millon, E.; Ntsoenzok, E.; Hakim, B.; Seiler, W.; Boulmer-Leborgne, C.; Perrière, J.

    2012-06-01

    Undoped and Nd-doped titanium dioxide anatase and rutile films have been grown by pulsed-laser deposition at 700 °C under 0.1 mbar O2. By selecting adequate substrates, TiO2 films doped with 1, 2 or 5 at.% Nd were grown and constituted with polycrystalline rutile, highly oriented (2 0 0) rutile film, or oriented (0 0 4) anatase. An UV to NIR photon conversion is evidenced in the films. Indeed, intense and well-resolved emission lines from Nd3+ have been observed upon excitation above the TiO2 bandgap at room temperature. The sensitised emission of Nd3+ is found to be much efficient in rutile than in anatase structure. Low temperature photoluminescence measurements lead to fine resolved peaks corresponding to the Nd3+ 4f transitions with different spectral characteristic according to the host matrix used. Photoluminescence dependence temperature evidences that the light emission from Nd3+ in anatase-based films is probably influenced by the presence of self-trapped excitons or by orbital interaction. Mechanisms of sensitisation host to Nd3+ are proposed for both matrixes. Finally, the Nd dopant concentration and the microstructure of TiO2 rutile films are found to affect the photoluminescence emission intensity. Rutile film (2 0 0) oriented is the most adapted host matrix to sensitise 1 at.% Nd3+ ions for an emission around 1064 nm making such Nd-doped layers interesting for photon conversion by down shifting process.

  14. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  15. Electric transport in 3D photonic crystal intermediate reflectors for micromorph thin-film tandem solar cells

    NASA Astrophysics Data System (ADS)

    Üpping, J.; Bielawny, A.; Lee, S.; Knez, M.; Carius, R.; Wehrspohn, R. B.

    2009-08-01

    The progress of 3D photonic intermediate reflectors for micromorph silicon tandem cells towards a first prototype cell is presented. Intermediate reflectors enhance the absorption of spectrally-selected light in the top cell and decrease the current mismatch between both junctions. A numerical method to predict filter properties for optimal current matching is presented. Our device is an inverted opal structure made of ZnO and fabricated using self-organized nanoparticles and atomic layer deposition for conformal coating. In particular, the influence of ZnO-doping and replicated cracks during drying of the opal is discussed with respect to conductivity and optical properties. A first prototype is compared to a state-of-the-art reference cell.

  16. Power Beamed Photon Sails: New Capabilities Resulting From Recent Maturation Of Key Solar Sail And High Power Laser Technologies

    SciTech Connect

    Montgomery, Edward E. IV

    2010-05-06

    This paper revisits some content in the First International Symposium on Beamed Energy Propulsion in 2002 related to the concept of propellantless in-space propulsion utilizing an external high energy laser to provide momentum to an ultralightweight (gossamer) spacecraft. The design and construction of the NanoSail-D solar sail demonstration spacecraft has demonstrated in space flight hardware the concept of small, very light--yet capable--spacecraft. The results of the Joint High Power Solid State Laser (JHPSSL) have also increased the effectiveness and reduced the cost of an entry level laser source. This paper identifies the impact from improved system parameters on current mission applications.

  17. Power Beamed Photon Sails: New Capabilities Resulting From Recent Maturation Of Key Solar Sail And High Power Laser Technologies

    NASA Astrophysics Data System (ADS)

    Montgomery, Edward E.

    2010-05-01

    This paper revisits some content in the First International Symposium on Beamed Energy Propulsion in 2002 related to the concept of propellantless in-space propulsion utilizing an external high energy laser to provide momentum to an ultralightweight (gossamer) spacecraft. The design and construction of the NanoSail-D solar sail demonstration spacecraft has demonstrated in space flight hardware the concept of small, very light—yet capable—spacecraft. The results of the Joint High Power Solid State Laser (JHPSSL) have also increased the effectiveness and reduced the cost of an entry level laser source. This paper identifies the impact from improved system parameters on current mission applications.

  18. An Environmentally Friendly Method for Testing Photocatalytic Inactivation of Cyanobacterial Propagation on a Hybrid Ag-TiO₂ Photocatalyst under Solar Illumination.

    PubMed

    Chang, Shu-Yu; Huang, Winn-Jung; Lu, Ben-Ren; Fang, Guor-Cheng; Chen, Yeah; Chen, Hsiu-Lin; Chang, Ming-Chin; Hsu, Cheng-Feng

    2015-12-01

    Cyanobacteria were inactivated under sunlight using mixed phase silver (Ag) and deposited titanium dioxide (TiO₂) coated on the surface of diatomite (DM) as a hybrid photocatalyst (Ag-TiO₂/DM). The endpoints of dose-response experiments were chlorophyll a, photosynthetic efficiency, and flow cytometry measurements. In vitro experiments revealed that axenic cultures of planktonic cyanobacteria lost their photosynthetic activity following photocatalyzed exposure to sunlight for more than 24 h. Nearly 92% of Microcystis aeruginosa cells lost their photosynthetic activity, and their cell morphology was severely damaged within 24 h of the reaction. Preliminary carbon-14 ((14)CO₃(-2)) results suggest that the complete inactivation of cyanobacteria arises from damage to cell wall components (peroxidation). A small concomitant increase in cell wall disorder and a consequent decrease in cell wall functional groups increase the cell wall fluidity prior to cell lysis. A high dosage of Ag-TiO₂/DM during photocatalysis increased the concentration of extracellular polymeric substances (EPSs) in the Microcystis aeruginosa suspension by up to approximately 260%. However, photocatalytic treatment had a small effect on the disinfection by-product (DBP) precursor, as revealed by only a slight increase in the formation of trihalomethanes (THMs) and haloacetic acids (HAAs). PMID:26690465

  19. An Environmentally Friendly Method for Testing Photocatalytic Inactivation of Cyanobacterial Propagation on a Hybrid Ag-TiO2 Photocatalyst under Solar Illumination

    PubMed Central

    Chang, Shu-Yu; Huang, Winn-Jung; Lu, Ben-Ren; Fang, Guor-Cheng; Chen, Yeah; Chen, Hsiu-Lin; Chang, Ming-Chin; Hsu, Cheng-Feng

    2015-01-01

    Cyanobacteria were inactivated under sunlight using mixed phase silver (Ag) and deposited titanium dioxide (TiO2) coated on the surface of diatomite (DM) as a hybrid photocatalyst (Ag-TiO2/DM). The endpoints of dose-response experiments were chlorophyll a, photosynthetic efficiency, and flow cytometry measurements. In vitro experiments revealed that axenic cultures of planktonic cyanobacteria lost their photosynthetic activity following photocatalyzed exposure to sunlight for more than 24 h. Nearly 92% of Microcystis aeruginosa cells lost their photosynthetic activity, and their cell morphology was severely damaged within 24 h of the reaction. Preliminary carbon-14 (14CO3−2) results suggest that the complete inactivation of cyanobacteria arises from damage to cell wall components (peroxidation). A small concomitant increase in cell wall disorder and a consequent decrease in cell wall functional groups increase the cell wall fluidity prior to cell lysis. A high dosage of Ag-TiO2/DM during photocatalysis increased the concentration of extracellular polymeric substances (EPSs) in the Microcystis aeruginosa suspension by up to approximately 260%. However, photocatalytic treatment had a small effect on the disinfection by-product (DBP) precursor, as revealed by only a slight increase in the formation of trihalomethanes (THMs) and haloacetic acids (HAAs). PMID:26690465

  20. Solar chameleons

    SciTech Connect

    Brax, Philippe

    2010-08-15

    We analyze the creation of chameleons deep inside the Sun (R{approx}0.7R{sub sun}) and their subsequent conversion to photons near the magnetized surface of the Sun. We find that the spectrum of the regenerated photons lies in the soft x-ray region, hence addressing the solar corona problem. Moreover, these back-converted photons originating from chameleons have an intrinsic difference with regenerated photons from axions: their relative polarizations are mutually orthogonal before Compton interacting with the surrounding plasma. Depending on the photon-chameleon coupling and working in the strong coupling regime of the chameleons to matter, we find that the induced photon flux, when regenerated resonantly with the surrounding plasma, coincides with the solar flux within the soft x-ray energy range. Moreover, using the soft x-ray solar flux as a prior, we find that with a strong enough photon-chameleon coupling, the chameleons emitted by the Sun could lead to a regenerated photon flux in the CAST magnetic pipes, which could be within the reach of CAST with upgraded detector performance. Then, axion helioscopes have thus the potential to detect and identify particle candidates for the ubiquitous dark energy in the Universe.

  1. Study of non-thermal photon production under different scenarios in solar flares. 1: Scenarios and formulations

    NASA Technical Reports Server (NTRS)

    Perez-Peraza, J.; Alvarez, M.; Gallegos, A.

    1985-01-01

    In order to study the overall phenomenology involved in solar flares, it is necessary to understand their individual manifestation before building a corresponding description of the global phenomenon. Here the concern is with the production of X and gamma rays in solar flares. Flares are initiated very often within the closed magnetic field configurations of active centers. According (2) when beta = kinetic energy density/magnetic energy density approximately 0.2, the magnetic trap configuration is destructed within the time scale of the impulsive phase of flares ( 100 s). A first particle acceleration stage occurs during this phase as indicated by impulsive microwave and hard X-rays bursts. In some flare events, when the field strength beta is very high, the broken field lines may close again, such that later, in the course of the flash and main phases more hot plasma of very high conductivity is created, and so, the field and frozen plasma expand outward, as the kinetic pressure inside the closed loops increases. The magnetically trapped particles excite strong Alfven wave turbulence of small transverse scale.

  2. Ag-bridged Ag2O nanowire network/TiO2 nanotube array p-n heterojunction as a highly efficient and stable visible light photocatalyst.

    PubMed

    Liu, Chengbin; Cao, Chenghao; Luo, Xubiao; Luo, Shenglian

    2015-03-21

    A unique Ag-bridged Ag2O nanowire network/TiO2 nanotube array p-n heterojunction (Ag-Ag2O/TiO2 NT) was fabricated by simple electrochemical method. Ag nanoparticles were firstly electrochemically deposited onto the surface of TiO2 NT and then were partly oxidized to Ag2O nanowires while the rest of Ag mother nanoparticles were located at the junctions of Ag2O nanowire network. The Ag-Ag2O/TiO2 NT heterostructure exhibited strong visible-light response, effective separation of photogenerated carriers, and high adsorption capacity. The integration of Ag-Ag2O self-stability structure and p-n heterojunction permitted high and stable photocatalytic activity of Ag-Ag2O/TiO2 NT heterostructure photocatalyst. Under 140-min visible light irradiation, the photocatalytic removal efficiency of both dye acid orange 7 (AO7) and industrial chemical p-nitrophenol (PNP) over Ag-Ag2O/TiO2 NT reached nearly 100% much higher than 17% for AO7 or 13% for PNP over bare TiO2 NT. After 5 successive cycles under 600-min simulated solar light irradiation, Ag-Ag2O/TiO2 NT remained highly stable photocatalytic activity. PMID:25528230

  3. Silicon nanostructures-induced photoelectrochemical solar water splitting for energy applications

    NASA Astrophysics Data System (ADS)

    Dadwal, U.; Ranjan, Neha; Singh, R.

    2016-05-01

    We study the photoelectrochemical (PEC) solar water splitting assisted with synthesized nanostructures. Si nanowires decorated with silver dendrite nanostructures have been synthesized using metal assisted wet chemical etching of (100) Si wafer. Etching has been carried out in an aqueous solution consisting of 5M HF and 0.02M AgNO3. Investigations showed that such type of semiconductor nanostructures act as efficient working electrodes for the splitting of normal water in PEC method. An enhancement in the photon-to-current conversion efficiency and solar-to-hydrogen evolution was observed for obtaining a practical source of clean and renewable fuel.

  4. Magnetron sputtering in the creation of photonic nanostructures derived from Sasakia Charonda Formosana-butterfly wings for applied in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Niu, Haihong; Zhou, Ru; Cheng, Cong; Zhang, Gonghai; Hu, Yu; Huang, Bin; Zhang, Shouwei; Shang, Xin; Xia, Mei; Xu, Jinzhang

    2016-09-01

    Creating new functional materials derived from the structures seen on butterfly wings has achieved interest in a variety of research topics. However, there need a concision approach could result in a high-quality, precise, and convenient process for the fabrication of complex nanostructures replication with unique functionalities based on the butterfly wings. Here we developed a pithy approach based on a magnetron sputtering metal Ti process for biotemplating used to refine hierarchically porous titanium dioxide photonic crystal nanostructures (TiO2sbnd PCN), themselves derived from nanostructures present on the wings of Sasakia Charonda Formosana (S. Charonda) butterflies. For the first time, the TiO2sbnd PCN were deposited on the top of the P25 active layer and were used to fabricate DSSCs as the light-scattering layers of photoanodes with power conversion efficiencies of up to 8.7%. Remarkably, a much enhanced photocurrent density and a prominent photoelectrochemical conversion capability have been achieved, which are exceeding most of the previously reported photoanodes as well as a similar butterflies replication-based device structure. Our study suggests many exciting opportunities of developing artificially engineered butterfly wing-based solar-to-fuel conversion.

  5. Dissociation energies of Ag-RG (RG = Ar, Kr, Xe) and AgO molecules from velocity map imaging studies.

    PubMed

    Cooper, Graham A; Kartouzian, Aras; Gentleman, Alexander S; Iskra, Andreas; van Wijk, Robert; Mackenzie, Stuart R

    2015-09-28

    The near ultraviolet photodissociation dynamics of silver atom-rare gas dimers have been studied by velocity map imaging. Ag-RG (RG = Ar, Kr, Xe) species generated by laser ablation are excited in the region of the C ((2)Σ(+))←X ((2)Σ(+)) continuum leading to direct, near-threshold dissociation generating Ag* ((2)P3/2) + RG ((1)S0) products. Images recorded at excitation wavelengths throughout the C ((2)Σ(+))←X ((2)Σ(+)) continuum, coupled with known atomic energy levels, permit determination of the ground X ((2)Σ(+)) state dissociation energies of 85.9 ± 23.4 cm(-1) (Ag-Ar), 149.3 ± 22.4 cm(-1) (Ag-Kr), and 256.3 ± 16.0 cm(-1) (Ag-Xe). Three additional photolysis processes, each yielding Ag atom photoproducts, are observed in the same spectral region. Two of these are markedly enhanced in intensity upon seeding the molecular beam with nitrous oxide, and are assigned to photodissociation of AgO at the two-photon level. These features yield an improved ground state dissociation energy for AgO of 15 965 ± 81 cm(-1), which is in good agreement with high level calculations. The third process results in Ag atom fragments whose kinetic energy shows anomalously weak photon energy dependence and is assigned tentatively to dissociative ionization of the silver dimer Ag2. PMID:26429006

  6. InGaAsN: A Novel Material for High-Efficiency Solar Cells and Advanced Photonic Devices

    SciTech Connect

    Allerman, Andrew A.; Follstaedt, David M.; Gee, James M.; Jones, Eric D.; Kurtz, Steven R.; Modine, Norman A.

    1999-07-01

    This report represents the completion of a 6 month Laboratory-Directed Research and Development (LDRD) program that focused on research and development of novel compound semiconductor, InGaAsN. This project seeks to rapidly assess the potential of InGaAsN for improved high-efficiency photovoltaic. Due to the short time scale, the project focused on quickly investigating the range of attainable compositions and bandgaps while identifying possible material limitations for photovoltaic devices. InGaAsN is a new semiconductor alloy system with the remarkable property that the inclusion of only 2% nitrogen reduces the bandgap by more than 30%. In order to help understand the physical origin of this extreme deviation from the typically observed nearly linear dependence of alloy properties on concentration, we have investigated the pressure dependence of the excited state energies using both experimental and theoretical methods. We report measurements of the low temperature photoluminescence energy of the material for pressures between ambient and 110 kbar. We describe a simple, density-functional-theory-based approach to calculating the pressure dependence of low lying excitation energies for low concentration alloys. The theoretically predicted pressure dependence of the bandgap is in excellent agreement with the experimental data. Based on the results of our calculations, we suggest an explanation for the strongly non-linear pressure dependence of the bandgap that, surprisingly, does not involve a nitrogen impurity band. Additionally, conduction-band mass measurements, measured by three different techniques, will be described and finally, the magnetoluminescence determined pressure coefficient for the conduction-band mass is measured. The design, growth by metal-organic chemical vapor deposition, and processing of an In{sub 0.07}Ga{sub 0.93}As{sub 0.98}N{sub 0.02} solar cell, with 1.0 eV bandgap, lattice matched to GaAs is described. The hole diffusion length in

  7. High-Quality AgGaTe2 Layers on Si Substrates with Ag2Te Buffer Layers

    NASA Astrophysics Data System (ADS)

    Uruno, Aya; Kobayashi, Masakazu

    2016-05-01

    AgGaTe2 layers were successfully grown on Si substrates by the close-spaced sublimation method. The Si substrates were confirmed to be etched during AgGaTe2 layer growth when the layer was grown directly on the substrate. To eliminate melt-back etching, a buffer layer of Ag2Te was introduced. It was found that the Ag2Te buffer layer changed into the AgGaTe2 layer during the growth process, and a uniform AgGaTe2 layer with an abrupt interface was formed. Both the diffusion of Ga into Ag2Te and the growth of AgGaTe2 occurred simultaneously. It was confirmed that uniform AgGaTe2 layers could be formed without any traces of the Ag2Te layer or melt-back etching by tuning the growth parameters. A solar cell was also fabricated using the p-AgGaTe2/n-Si heterojunction. This solar cell showed conversion efficiency of approximately 3%.

  8. High-Quality AgGaTe2 Layers on Si Substrates with Ag2Te Buffer Layers

    NASA Astrophysics Data System (ADS)

    Uruno, Aya; Kobayashi, Masakazu

    2016-09-01

    AgGaTe2 layers were successfully grown on Si substrates by the close-spaced sublimation method. The Si substrates were confirmed to be etched during AgGaTe2 layer growth when the layer was grown directly on the substrate. To eliminate melt-back etching, a buffer layer of Ag2Te was introduced. It was found that the Ag2Te buffer layer changed into the AgGaTe2 layer during the growth process, and a uniform AgGaTe2 layer with an abrupt interface was formed. Both the diffusion of Ga into Ag2Te and the growth of AgGaTe2 occurred simultaneously. It was confirmed that uniform AgGaTe2 layers could be formed without any traces of the Ag2Te layer or melt-back etching by tuning the growth parameters. A solar cell was also fabricated using the p-AgGaTe2/n-Si heterojunction. This solar cell showed conversion efficiency of approximately 3%.

  9. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1985-01-01

    The study of photon-photon collisions has progressed enormously, stimulated by new data and new calculational tools for QCD. In the future we can expect precise determinations of ..cap alpha../sub s/ and ..lambda../sup ms/ from the ..gamma..*..gamma.. ..-->.. ..pi../sup 0/ form factor and the photon structure function, as well as detailed checks of QCD, determination of the shape of the hadron distribution amplitudes from ..gamma gamma.. ..-->.. H anti H, reconstruction of sigma/sub ..gamma gamma../ from exclusive channels at low W/sub ..gamma gamma../, definitive studies of high p/sub T/ hadron and jet production, and studies of threshold production of charmed systems. Photon-photon collisions, along with radiative decays of the psi and UPSILON, are ideal for the study of multiquark and gluonic resonances. We have emphasized the potential for resonance formation near threshold in virtually every hadronic exclusive channel, including heavy quark states c anti c c anti c, c anti c u anti u, etc. At higher energies SLC, LEP, ...) parity-violating electroweak effects and Higgs production due to equivalent Z/sup 0/ and W/sup + -/ beams from e ..-->.. eZ/sup 0/ and e ..-->.. nu W will become important. 44 references.

  10. Study of photon emission by electron capture during solar nuclei acceleration. 2: Delimitation of conditions for charge transfert establishment

    NASA Technical Reports Server (NTRS)

    Perez-Peraza, J.; Alvarez, M.; Gallegos, A.

    1985-01-01

    The conditions for establishment of charge transfer during acceleration of nuclei up to Fe, for typical conditions of solar flare regions T = 5 x 10 to the 3rd power to 2.5 x 10 to the 8th power degrees K were explored. Results show that such conditions are widely assorted, depending on the acceleration mechanism, the kind of projections and their velocity, the target elements, the source temperature and consequently on the degree of ionization of matter and the local charge state of the accelerated ions. Nevertheless, in spite of that assorted behavior, there are some general tendencies that can be summarized as follows. In atomic H electron capture is systematically established from thermal energies up to high energies, whatever the element and for both acceleration process. For a given element and fixed temperature (T), the probability and energy domain of electron capture and loss with Fermi are higher than with Betatron acceleration. For a given acceleration process the heavier the ion the higher the probability and the wider the energy range for electron capture and loss. For given acceleration mechanism and fixed element the importance and energy domain of capture and loss increase with T: for those reasons, the energy range of charge equilibrium (illustrated with solid lines on the next figs.) is wider with Fermi and increases with temperature and atomic number of projectiles. For the same reasons, electron loss is smaller while the lighter the element, the lower the temperature and the Betatron process, such that there are conditions for which electron loss is not allowed at low energies, but only electron capture is established.

  11. Preparation, characterization, and photocatalytic activity of porous AgBr@Ag and AgBrI@Ag plasmonic photocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Tian, Baozhu; Zhang, Jinlong; Xiong, Tianqing; Wang, Tingting

    2014-02-01

    Porous AgBr@Ag and AgBrI@Ag plasmonic photocatalysts were synthesized by a multistep route, including a dealloying method to prepare porous Ag, a transformation from Ag to AgBr and AgBrI, and a photo-reduction process to form Ag nanoparticles on the surface of AgBr and AgBrI. It was found that the porous structure kept unchanged during Ag was transferred into AgBr, AgBrI, AgBr@Ag, and AgBrI@Ag. Both porous AgBr@Ag and porous AgBrI@Ag showed much higher visible-light photocatalytic activity than cubic AgBr@Ag for the degradation of methyl orange, which is because the interconnected pore channels not only provide more reactive sites but also favor the transportation of photo-generated electrons and holes. For AgBrI@Ag, AgBrI solid solution formed at the interface of AgBr and AgI, and the phase junction can effectively separate the photo-generated electrons and holes, favorable to the improvement of photocatalytic activity. The optimal I content for obtaining the highest activity is ∼10 at.%.

  12. Decoupling optical and electronic optimization of organic solar cells using high-performance temperature-stable TiO{sub 2}/Ag/TiO{sub 2} electrodes

    SciTech Connect

    Kim, Kwang-Dae; Pfadler, Thomas; Zimmermann, Eugen; Feng, Yuyi; Weickert, Jonas Schmidt-Mende, Lukas; Dorman, James A.

    2015-10-01

    An electrode structured with a TiO{sub 2}/Ag/TiO{sub 2} (TAT) multilayer as indium tin oxide (ITO) replacement with a superior thermal stability has been successfully fabricated. This electrode allows to directly tune the optical cavity mode towards maximized photocurrent generation by varying the thickness of the layers in the sandwich structure. This enables tailored optimization of the transparent electrode for different organic thin film photovoltaics without alteration of their electro-optical properties. Organic photovoltaic featuring our TAT multilayer shows an improvement of ∼12% over the ITO reference and allows power conversion efficiencies (PCEs) up to 8.7% in PTB7:PC{sub 71}BM devices.

  13. Achieving an Accurate Surface Profile of a Photonic Crystal for Near-Unity Solar Absorption in a Super Thin-Film Architecture.

    PubMed

    Kuang, Ping; Eyderman, Sergey; Hsieh, Mei-Li; Post, Anthony; John, Sajeev; Lin, Shawn-Yu

    2016-06-28

    In this work, a teepee-like photonic crystal (PC) structure on crystalline silicon (c-Si) is experimentally demonstrated, which fulfills two critical criteria in solar energy harvesting by (i) its Gaussian-type gradient-index profile for excellent antireflection and (ii) near-orthogonal energy flow and vortex-like field concentration via the parallel-to-interface refraction effect inside the structure for enhanced light trapping. For the PC structure on 500-μm-thick c-Si, the average reflection is only ∼0.7% for λ = 400-1000 nm. For the same structure on a much thinner c-Si ( t = 10 μm), the absorption is near unity (A ∼ 99%) for visible wavelengths, while the absorption in the weakly absorbing range (λ ∼ 1000 nm) is significantly increased to 79%, comparing to only 6% absorption for a 10-μm-thick planar c-Si. In addition, the average absorption (∼94.7%) of the PC structure on 10 μm c-Si for λ = 400-1000 nm is only ∼3.8% less than the average absorption (∼98.5%) of the PC structure on 500 μm c-Si, while the equivalent silicon solid content is reduced by 50 times. Furthermore, the angular dependence measurements show that the high absorption is sustained over a wide angle range (θinc = 0-60°) for teepee-like PC structure on both 500 and 10-μm-thick c-Si. PMID:27258082

  14. Fabrication of plasmonic AgBr/Ag nanoparticles-sensitized TiO2 nanotube arrays and their enhanced photo-conversion and photoelectrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Qingyao; Qiao, Jianlei; Jin, Rencheng; Xu, Xiaohui; Gao, Shanmin

    2015-03-01

    Plasmonic photosensitizer AgBr/Ag nanospheres supported on TiO2 nanotube arrays (TiO2 NTs) are prepared by successive ionic layer adsorption and reaction (SILAR) technique followed by photoreduction methods. The structural and surface morphological properties of AgBr/Ag nanoparticles sensitized TiO2 NTs and their photoelectrochemical performance are investigated and discussed. A detailed formation mechanism of the TiO2 NTs/AgBr/Ag is proposed. The TiO2 NTs/AgBr/Ag exhibit excellent photocurrent and photoelectrocatalytic activities under visible light irradiation. Efficient utilization of solar energy to create electron-hole pairs is attributed to the significant visible light response and surface plasmon resonance of Ag nanoparticles. This finding indicates that the high photosensitivity of the TiO2 NTs-based surface plasmon resonance materials could be applied toward the development of new plasmonic visible-light-sensitive photovoltaic fuel cells and photocatalysts.

  15. Antigravity Acts on Photons

    NASA Astrophysics Data System (ADS)

    Brynjolfsson, Ari

    2002-04-01

    Einstein's general theory of relativity assumes that photons don't change frequency as they move from Sun to Earth. This assumption is correct in classical physics. All experiments proving the general relativity are in the domain of classical physics. This include the tests by Pound et al. of the gravitational redshift of 14.4 keV photons; the rocket experiments by Vessot et al.; the Galileo solar redshift experiments by Krisher et al.; the gravitational deflection of light experiments by Riveros and Vucetich; and delay of echoes of radar signals passing close to Sun as observed by Shapiro et al. Bohr's correspondence principle assures that quantum mechanical theory of general relativity agrees with Einstein's classical theory when frequency and gravitational field gradient approach zero, or when photons cannot interact with the gravitational field. When we treat photons as quantum mechanical particles; we find that gravitational force on photons is reversed (antigravity). This modified theory contradicts the equivalence principle, but is consistent with all experiments. Solar lines and distant stars are redshifted in accordance with author's plasma redshift theory. These changes result in a beautiful consistent cosmology.

  16. Spaceborne Photonics Institute

    NASA Technical Reports Server (NTRS)

    Venable, D. D.; Farrukh, U. O.; Han, K. S.; Hwang, I. H.; Jalufka, N. W.; Lowe, C. W.; Tabibi, B. M.; Lee, C. J.; Lyons, D.; Maclin, A.

    1994-01-01

    This report describes in chronological detail the development of the Spaceborne Photonics Institute as a sustained research effort at Hampton University in the area of optical physics. This provided the research expertise to initiate a PhD program in Physics. Research was carried out in the areas of: (1) modelling of spaceborne solid state laser systems; (2) amplified spontaneous emission in solar pumped iodine lasers; (3) closely simulated AM0 CW solar pumped iodine laser and repeatedly short pulsed iodine laser oscillator; (4) a materials spectroscopy and growth program; and (5) laser induced fluorescence and atomic and molecular spectroscopy.

  17. AGS experiments - 1994, 1995, 1996

    SciTech Connect

    Depken, J.C.

    1997-01-01

    This report contains the following information on the Brookhaven AGS Accelerator complex: FY 1996 AGS schedule as run; FY 1997 AGS schedule (working copy); AGS beams 1997; AGS experimental area FY 1994 physics program; AGS experimental area FY 1995 physics program; AGS experimental area FY 1996 physics program; AGS experimental area FY 1997 physics program (in progress); a listing of experiments by number; two-phage summaries of each experiment begin here, also ordered by number; listing of publications of AGS experiments begins here; and listing of AGS experimenters begins here.

  18. Space solar cell technology development - A perspective

    NASA Technical Reports Server (NTRS)

    Scott-Monck, J.

    1982-01-01

    The developmental history of photovoltaics is examined as a basis for predicting further advances to the year 2000. Transistor technology was the precursor of solar cell development. Terrestrial cells were modified for space through changes in geometry and size, as well as the use of Ag-Ti contacts and manufacture of a p-type base. The violet cell was produced for Comsat, and involved shallow junctions, new contacts, and an enhanced antireflection coating for better radiation tolerance. The driving force was the desire by private companies to reduce cost and weight for commercial satellite power supplies. Liquid phase epitaxial (LPE) GaAs cells are the latest advancement, having a 4 sq cm area and increased efficiency. GaAs cells are expected to be flight ready in the 1980s. Testing is still necessary to verify production techniques and the resistance to electron and photon damage. Research will continue in CVD cell technology, new panel technology, and ultrathin Si cells.

  19. Conversion of above- and below-bandgap photons via InAs quantum dot media embedded into GaAs solar cell

    SciTech Connect

    Sablon, K.; Little, J.; Vagidov, N.; Li, Y.; Mitin, V.; Sergeev, A.

    2014-06-23

    Quantum dots (QDs) provide photovoltaic conversion of below-bandgap photons due to multistep electron transitions. QDs also increase conversion efficiency of the above-bandgap photons due to extraction of electrons from QDs via Coulomb interaction with hot electrons excited by high-energy photons. Nanoscale potential profile (potential barriers) and nanoscale band engineering (AlGaAs atomically thin barriers) allow for suppression of photoelectron capture to QDs. To study these kinetic effects and to distinguish them from the absorption enhancement due to light scattering on QDs, we investigate long, 3-μm base GaAs devices with various InAs QD media with 20 and 40 QD layers. Quantum efficiency measurements show that, at least at low doping, the multistep processes in QD media are strongly affected by the wetting layer (WL). The QD media with WLs provide substantial conversion of below-bandgap photons and for devices with 40 QD layers the short circuit current reaches 29.2 mA/cm{sup 2}. The QD media with band-engineered AlGaAs barriers and reduced wetting layers (RWL) enhance conversion of high-energy photons and decrease the relaxation (thermal) losses.

  20. Conversion of above- and below-bandgap photons via InAs quantum dot media embedded into GaAs solar cell

    NASA Astrophysics Data System (ADS)

    Sablon, K.; Little, J.; Vagidov, N.; Li, Y.; Mitin, V.; Sergeev, A.

    2014-06-01

    Quantum dots (QDs) provide photovoltaic conversion of below-bandgap photons due to multistep electron transitions. QDs also increase conversion efficiency of the above-bandgap photons due to extraction of electrons from QDs via Coulomb interaction with hot electrons excited by high-energy photons. Nanoscale potential profile (potential barriers) and nanoscale band engineering (AlGaAs atomically thin barriers) allow for suppression of photoelectron capture to QDs. To study these kinetic effects and to distinguish them from the absorption enhancement due to light scattering on QDs, we investigate long, 3-μm base GaAs devices with various InAs QD media with 20 and 40 QD layers. Quantum efficiency measurements show that, at least at low doping, the multistep processes in QD media are strongly affected by the wetting layer (WL). The QD media with WLs provide substantial conversion of below-bandgap photons and for devices with 40 QD layers the short circuit current reaches 29.2 mA/cm2. The QD media with band-engineered AlGaAs barriers and reduced wetting layers (RWL) enhance conversion of high-energy photons and decrease the relaxation (thermal) losses.

  1. Photon absorptiometry

    SciTech Connect

    Velchik, M.G.

    1987-01-01

    Recently, there has been a renewed interest in the detection and treatment of osteoporosis. This paper is a review of the merits and limitations of the various noninvasive modalities currently available for the measurement of bone mineral density with special emphasis placed upon the nuclear medicine techniques of single-photon and dual-photon absorptiometry. The clinicians should come away with an understanding of the relative advantages and disadvantages of photon absorptiometry and its optimal clinical application. 49 references.

  2. Recent Development of Plasmonic Resonance-Based Photocatalysis and Photovoltaics for Solar Utilization.

    PubMed

    Fan, Wenguang; Leung, Michael K H

    2016-01-01

    Increasing utilization of solar energy is an effective strategy to tackle our energy and energy-related environmental issues. Both solar photocatalysis (PC) and solar photovoltaics (PV) have high potential to develop technologies of many practical applications. Substantial research efforts are devoted to enhancing visible light activation of the photoelectrocatalytic reactions by various modifications of nanostructured semiconductors. This review paper emphasizes the recent advancement in material modifications by means of the promising localized surface plasmonic resonance (LSPR) mechanisms. The principles of LSPR and its effects on the photonic efficiency of PV and PC are discussed here. Many research findings reveal the promise of Au and Ag plasmonic nanoparticles (NPs). Continual investigation for increasing the stability of the plasmonic NPs will be fruitful. PMID:26848648

  3. Photon Colliders

    SciTech Connect

    Gronberg, J

    2002-10-07

    A photon collider interaction region has the possibility of expanding the physics reach of a future TeV scale electron-positron collider. A survey of ongoing efforts to design the required lasers and optics to create a photon collider is presented in this paper.

  4. The AgNORs.

    PubMed

    Derenzini, M

    2000-04-01

    The structure and the function of interphase AgNORs and the importance of the "AgNOR" parameter in tumor pathology have been reviewed. Interphase AgNORs are structural-functional units of the nucleolus in which all the components necessary for ribosomal RNA synthesis are located. Two argyrophilic proteins involved in rRNA transcription and processing, nucleolin and nucleophosmin, are associated with interphase AgNORs and are responsible for their stainability with silver methods, thus allowing interphase AgNORs to be visulaized at light microscopic level, also in routine cyto-histopathological preparations. The number of interphase AgNORs is strictly related to rRNA transcriptional activity and, in continuously proliferating cells, to the rapidity of cell proliferation. Evaluation of the quantitative distribution of interphase AgNORs has been applied in tumor pathology both for diagnostic and prognostic purposes. The "AgNOR" parameter has been proved to represent a reliable tool for defining the clinical outcome of cancer disease, being an independent prognostic factor in many types of tumors. PMID:10588056

  5. AgRISTARS

    NASA Technical Reports Server (NTRS)

    1984-01-01

    An introduction to the overall AgRISTARS program, a general statement on progress, and separate summaries of the activities of each project, with emphasis on the technical highlights are presented. Organizational and management information on AgRISTARS is included in the appendices, as is a complete bibliography of publication and reports.

  6. Enhanced absorption of Ag diamond-type nanoantenna arrays

    NASA Astrophysics Data System (ADS)

    Yuan, Zong-heng; Li, Xiao-nan; Guo, Ya-dong; Huang, Jing

    2015-01-01

    The optical metal nanoantenna on thin film solar cell is effective to enhance light absorption. In this paper, the diamond-type Ag nanoantenna arrays are proposed for increasing the efficiency of solar cells by localized surface plasmons resonance (LSPR). The effect of metal nanoantenna on the absorption enhancement is theoretically investigated by the finite difference time domain (FDTD) method. Broadband absorption enhancements in both visible and near-infrared regions are demonstrated in case of solar cell with diamond-type Ag nanoantennas. The spectral response is manipulated by geometrical parameters of the nanoantennas. The maximum enhancement factor of 1.51 for solar cell is obtained. For comparison, the other three nanoantennas are also analyzed. The results show that the solar cell with optimized diamond-type nanoantenna arrays is more efficient in optical absorption.

  7. AGS experiments: 1993 - 1994 - 1995

    SciTech Connect

    Depken, J.C.

    1996-04-01

    This report contains: FY 1995 AGS Schedule as Run; FY 1996-97 AGE Schedule (working copy); AGS Beams 1995; AGS Experimental Area FY 1993 Physics Program; AGS Experimental Area FY 1994 Physics Program; AGS Experimental Area FY 1995 Physics Program; AGS Experimental Area FY 1996 Physics Program (In progress); A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Listing of publications of AGS experiments begins here; and Listing of AGS experimenters begins here. This is the twelfth edition.

  8. Photon Flux Amplification for Enhancing Photonic Laser Propulsive Forces

    NASA Technical Reports Server (NTRS)

    Gray, Perry A.; Carruth, M. Ralph, Jr.; Edwards, David L.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    An enhancement to the available force from a solar/laser sail is being investigated. This enhancement involves the use of a high power laser as the main source of propulsion or as a supplement to a solar sail. The enhancement utilizes a high power laser and multiple photon reflections to amplify the laser photon flux impinging on a sail. It is thus possible to amplify the force by as much as a factor of 50 or more. This paper explores the use of a stable optical cavity and will illustrate the optics involved in producing a stable cavity. A breadboard of the optical system was constructed and a stable cavity was demonstrated. Once the breadboard system was complete and a stable cavity achieved, the system was placed in vacuum and photon force amplification was measured using a vacuum compatible microbalance.

  9. Suppression of thermal carrier escape and efficient photo-carrier generation by two-step photon absorption in InAs quantum dot intermediate-band solar cells using a dot-in-well structure

    SciTech Connect

    Asahi, S.; Teranishi, H.; Kasamatsu, N.; Kada, T.; Kaizu, T.; Kita, T.

    2014-08-14

    We investigated the effects of an increase in the barrier height on the enhancement of the efficiency of two-step photo-excitation in InAs quantum dot (QD) solar cells with a dot-in-well structure. Thermal carrier escape of electrons pumped in QD states was drastically reduced by sandwiching InAs/GaAs QDs with a high potential barrier of Al{sub 0.3}Ga{sub 0.7}As. The thermal activation energy increased with the introduction of the barrier. The high potential barrier caused suppression of thermal carrier escape and helped realize a high electron density in the QD states. We observed efficient two-step photon absorption as a result of the high occupancy of the QD states at room temperature.

  10. Photon generator

    DOEpatents

    Srinivasan-Rao, Triveni

    2002-01-01

    A photon generator includes an electron gun for emitting an electron beam, a laser for emitting a laser beam, and an interaction ring wherein the laser beam repetitively collides with the electron beam for emitting a high energy photon beam therefrom in the exemplary form of x-rays. The interaction ring is a closed loop, sized and configured for circulating the electron beam with a period substantially equal to the period of the laser beam pulses for effecting repetitive collisions.

  11. High-Performance Flexible Perovskite Solar Cells by Using a Combination of Ultrasonic Spray-Coating and Low Thermal Budget Photonic Curing

    SciTech Connect

    Sanjib, Das; Yang, Bin; Gu, Gong; Joshi, Pooran C; Ivanov, Ilia N; Rouleau, Christopher; Aytug, Tolga; Geohegan, David B; Xiao, Kai

    2015-01-01

    Realizing the commercialization of high-performance and robust perovskite solar cells urgently requires the development of economically scalable processing techniques. Here we report a high-throughput ultrasonic spray-coating (USC) process capable of fabricating perovskite film-based solar cells on glass substrates with power conversion efficiency (PCE) as high as 13.04%. Perovskite films with high uniformity, crystallinity, and surface coverage are obtained in a single step. Moreover, we report USC processing on TiOx/ITO-coated polyethylene terephthalate (PET) substrates to realize flexible perovskite solar cells with PCE as high as 8.02% that are robust under mechanical stress. In this case, an optical curing technique was used to achieve a highly-conductive TiOx layer on flexible PET substrates for the first time. The high device performance and reliability obtained by this combination of USC processing with optical curing appears very promising for roll-to-roll manufacturing of high-efficiency, flexible perovskite solar cells.

  12. Super-high photocatalytic activity, stability and improved photocatalytic mechanism of monodisperse AgBr doped with In.

    PubMed

    Song, Limin; Zhang, Shujuan; Zhang, Shuna

    2015-12-15

    Monodisperse In(3+) doped AgBr (In-AgBr) nanoparticles were synthesized by a hydrothermal route. The pure AgBr and In-AgBr samples were investigated by X-ray powder diffraction, transmission electron microscopy, ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy, measurement of total organic carbon, and electron paramagnetic resonance spectrometry. In-AgBr was more photocatalytically active than pure AgBr in photodegradation of 20 mg/L methyl orange under visible light irradiation (λ>420 nm). The 0.05 mol/L In-AgBr sample showed the highest photodegradation efficiency and high stability. The doped In(3+) expanded the light absorption range, reduced the band gap of AgBr and improved the utilization of photons. The additional In(3+) can inhibit the formation of Ag particles on the surface of AgBr, which can further stabilize AgBr. The doped In(3+) in AgBr served as a temporary site for trapping of photoinduced electrons, and thereby obviously restrained the recombination of photoinduced electron-hole pairs on the surface of AgBr. The enhanced photocatalytic ability of In-AgBr may be mainly attributed to the improved separation efficiency of photogenerated charges. PMID:26259096

  13. Photoionizaton electronic spectroscopy of AgK

    NASA Astrophysics Data System (ADS)

    Yeh, C. S.; Robbins, D. L.; Pilgrim, J. S.; Duncan, M. A.

    1993-05-01

    An electronic spectrum is observed for the new heteronuclear metal dimer, AgK. Two electronic states are observed with origins near 315 nm. Spectra are detected for three isotopomers with mass-resolved one-color two-photon photoionization spectroscopy (R2PI). The vibrational bands in the more intense state (ω e = 85.8 cm -1) have rotational structure consistent with a 1Σ + → 1Π transition. This structure is red-shaded, consistent with an excited state having a significantly longer bond (3.02 Å) than the ground state (2.40 Å). The possible importance of ionic bonding is discussed.

  14. Luminescence of fixed site Ag nanoclusters in a simple oxyfluoride glass host and plasmon absorption of amorphous Ag nanoparticles in a complex oxyfluoride glass host

    NASA Astrophysics Data System (ADS)

    Shestakov, Mikhail V.; Meledina, Maria; Turner, Stuart; Baekelant, Wouter; Verellen, Niels; Chen, Xianmei; Hofkens, Johan; Van Tendeloo, Gustaaf; Moshchalkov, Victor V.

    2015-01-01

    Ag nanocluster-doped glasses have been prepared by a conventional melt-quenching method. The effect of melt temperature and dwell time on the formation of Ag nanoclusters and Ag nanoparticles in simple host oxyfluoride glasses has been studied. The increase of melt temperature and dwell time results in the dissolution of Ag nanoparticles and substantial red-shift of absorption and photoluminescence spectra of the prepared glasses. The quantum yield of the glasses is ~ 5% and does not depend on melt temperature and dwell time. The prepared glasses may be used as red phosphors or down-conversion layers for solar-cells.

  15. Enhanced reverse saturable absorption in graphene/Ag2S organic glasses.

    PubMed

    Ouyang, Qiuyun; Di, Xinpeng; Lei, Zhenyu; Qi, Lihong; Li, Chunyan; Chen, Yujin

    2013-07-14

    G/Ag2S composites were synthesized for the first time by a hydrothermal method. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analysis demonstrated that Ag2S nanoparticles with a diameter of about 130 nm uniformly covered the graphene surfaces. G/Ag2S composites were dispersed in methyl methacrylate (MMA), polymerized at 75 °C for 30-35 min, and finally dried at 45 °C for 10 h, to afford G/Ag2S/PMMA organic glasses. The nonlinear absorption (NLA) properties of the G/Ag2S/PMMA organic glasses with different amounts of G/Ag2S were investigated by an open-aperture Z-scan technique. The experimental results showed that the G/Ag2S/PMMA organic glass with an appropriate amount of G/Ag2S exhibited enhanced reverse saturable absorption (RSA) properties compared to G/PMMA and Ag2S/PMMA organic glasses, which was attributed to the notable synergistic effects between graphene and Ag2S. Both one-photon absorption (OPA) in Ag2S and two-photon absorption (TPA) in graphene played important roles in RSA processes of the G/Ag2S/PMMA organic glasses. The effective NLA coefficient βeff of the G/Ag2S/PMMA organic glasses was in the order of 10(3) cm GW(-1). Thus this kind of organic glasses have great promise in optical limiter and optical shutter applications. PMID:23715155

  16. Nano-crystalline silicon solar cell architecture with absorption at the classical 4n2 limit

    SciTech Connect

    Biswas, Rana; Xu, Chun

    2011-07-04

    We develop a periodically patterned conformal photonic-plasmonic crystal based solar architecture for a nano-crystalline silicon solar cell, through rigorous scattering matrix simulations. The solar cell architecture has a periodic array of tapered silver nano-pillars as the back-reflector coupled with a conformal periodic structure at the top of the cell. The absorption and maximal current, averaged over the entire range of wavelengths, for this solar cell architecture is at the semi-classical 4n{sup 2} limit over a range of common thicknesses (500-1500 nm) and slightly above the 4n{sup 2} limit for a 500 nm nc-Si cell. The absorption exceeds the 4n{sup 2} limit, corrected for reflection loss at the top surface. The photonic crystal cell current is enhanced over the flat Ag back-reflector by 60%, for a thick 1000 nm nc-Si layer, where predicted currents exceed 31 mA/cm{sup 2}. The conformal structure at the top surface focuses light within the absorber layer. There is plasmonic concentration of light, with intensity enhancements exceeding 7, near the back reflector that substantially enhances absorption.

  17. Green photonics

    NASA Astrophysics Data System (ADS)

    Quan, Frederic

    2012-02-01

    Photonics, the broad merger of electronics with the optical sciences, encompasses such a wide swath of technology that its impact is almost universal in our everyday lives. This is a broad overview of some aspects of the industry and their contribution to the ‘green’ or environmental movement. The rationale for energy conservation is briefly discussed and the impact of photonics on our everyday lives and certain industries is described. Some opinions from industry are presented along with market estimates. References are provided to some of the most recent research in these areas.

  18. Photons Revisited

    NASA Astrophysics Data System (ADS)

    Batic, Matej; Begalli, Marcia; Han, Min Cheol; Hauf, Steffen; Hoff, Gabriela; Kim, Chan Hyeong; Kim, Han Sung; Grazia Pia, Maria; Saracco, Paolo; Weidenspointner, Georg

    2014-06-01

    A systematic review of methods and data for the Monte Carlo simulation of photon interactions is in progress: it concerns a wide set of theoretical modeling approaches and data libraries available for this purpose. Models and data libraries are assessed quantitatively with respect to an extensive collection of experimental measurements documented in the literature to determine their accuracy; this evaluation exploits rigorous statistical analysis methods. The computational performance of the associated modeling algorithms is evaluated as well. An overview of the assessment of photon interaction models and results of the experimental validation are presented.

  19. Performance of Hydrogenated a-Si:H Solar Cells with Downshifting Coating: Preprint

    SciTech Connect

    Nemeth, B.; Xu, Y.; Wang, H.; Sun, T.; Lee, B. G.; Duda, A.; Wang, Q.

    2011-05-01

    We apply a thin luminescent downshifting (LDS) coating to a hydrogenated amorphous Si (a-Si:H) solar cell and study the mechanism of possible current enhancement. The conversion material used in this study converts wavelengths below 400 nm to a narrow line around 615 nm. This material is coated on the front of the glass of the a-Si:H solar cell with a glass/TCO/p/i/n/Ag superstrate configuration. The initial efficiency of the solar cell without the LDS coating is above 9.0 % with open circuit voltage of 0.84 V. Typically, the spectral response below 400 nm of an a-Si:H solar cell is weaker than that at 615 nm. By converting ultraviolet (UV) light to red light, the solar cell will receive more red photons; therefore, solar cell performance is expected to improve. We observe evidence of downshifting in reflectance spectra. The cell Jsc decreases by 0.13 mA/cm2, and loss mechanisms are identified.

  20. Synchrotron Micro-XRF Mapping of Ag Storage in a Coastal Marine Diatom: Implications for Ag as a Novel Paleoproductivity Proxy

    NASA Astrophysics Data System (ADS)

    King, M. W.; Hendy, I. L.; Lai, B.

    2012-12-01

    Silver (Ag) has potential for use as a paleoproductivity proxy in environments where a high flux of organic matter creates reducing conditions in sediments. Its proposed sequestration under reducing conditions as the species Ag2S confers an advantage over the more conventional productivity proxy barite, which becomes unreliable when sulfate reduction occurs in sediments. Other conventional productivity proxies (organic carbon and biogenic silica) are subject to rapid remineralization during early diagenesis, whereas Ag is likely to be preserved. Prior studies have hinted that Ag may be delivered to sediments via diatom debris. However, whether Ag is primarily associated with the frustule silica matrix or with diatom organic matter has not been established, and hence the mechanism of Ag delivery to sediments remains ambiguous. In this study we investigated the location of Ag storage in diatoms using synchrotron micro-XRF to map Ag, along with Ca, P, S, Si, and Fe, in single cells of the coastal marine diatom Thalassiosira pseudonana. Diatoms were cultured in the laboratory with Ag added to the growth medium at 50 and 100 ppb. Samples were analyzed at the sub-micron scale at the Advanced Photon Source, Argonne National Laboratory. Detectable Ag concentrations appear to be localized to intracellular "hotspots" that are not associated with frustule Si, either as part of the matrix or surface-adsorbed. Silver "hotspots" are co-localized with Fe, suggesting that Ag is stored within vacuoles, as recently shown for Fe in centric diatoms. Overall, our results support the hypothesis that Ag is delivered to sediments with diatom organic matter and suggest a common strategy by centric diatoms for intracellular sequestration of micronutrient (Fe) and nonessential (Ag) trace metals.

  1. The Role of Order in the Amplification of Light-Energy Conversion in a Dye-Sensitized Solar Cell Coupled to a Photonic Crystal.

    PubMed

    Fayad, Remi; Halaoui, Lara

    2016-01-18

    We investigate the cause of amplification of light-energy conversion when coupling a nc-TiO2 film to a TiO2 inverse opal by comparing it to an inverse TiO2 glass (i-TiO2 -g) fabricated with the exact monodisperse air-hole size as an inverse opal with a stop band at 600 nm (600-i-TiO2 -o). A significant twofold average gain in the photon-to-current conversion efficiency is measured to the red of the stop band at the 600-i-TiO2 -o/nc-TiO2 bilayer under front-wall and back-wall illumination, greater than the gain within the stop band. A smaller amplification is measured under front-wall illumination-and no gain is measured under back-wall illumination-for i-TiO2 -g/nc-TiO2 at these energies. The photonic crystal therefore causes trapping of light through the bilayer, not only within the gap but also to the red, at frequencies within its dielectric band. This light-trapping effect is found to be dependent on structural order, as a highly disordered inverse glass film with the same air-hole size and thickness does not yield the same gain. A drop in the transmission of light is measured within the same frequencies to the red of the stop band upon adding nc-TiO2 to 600-i-TiO2 -o, consistent with light trapping in the bilayer. PMID:26643111

  2. Photon Luminescence of the Moon

    NASA Technical Reports Server (NTRS)

    Wilson, T.L.; Lee, K.T.

    2009-01-01

    Luminescence is typically described as light emitted by objects at low temperatures, induced by chemical reactions, electrical energy, atomic interactions, or acoustical and mechanical stress. An example is photoluminescence created when photons (electromagnetic radiation) strike a substance and are absorbed, resulting in the emission of a resonant fluorescent or phosphorescent albedo. In planetary science, there exists X-ray fluorescence induced by sunlight absorbed by a regolith a property used to measure some of the chemical composition of the Moon s surface during the Apollo program. However, there exists an equally important phenomenon in planetary science which will be designated here as photon luminescence. It is not conventional photoluminescence because the incoming radiation that strikes the planetary surface is not photons but rather cosmic rays (CRs). Nevertheless, the result is the same: the generation of a photon albedo. In particular, Galactic CRs (GCRs) and solar energetic particles (SEPs) both induce a photon albedo that radiates from the surface of the Moon. Other particle albedos are generated as well, most of which are hazardous (e.g. neutrons). The photon luminescence or albedo of the lunar surface induced by GCRs and SEPs will be derived here, demonstrating that the Moon literally glows in the dark (when there is no sunlight or Earthshine). This extends earlier work on the same subject [1-4]. A side-by-side comparison of these two albedos and related mitigation measures will also be discussed.

  3. 76 FR 23574 - Combined Notice of Filings #1

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-27

    ... Company submits tariff filing per 35.13(a)(2)(iii: SGIA WDT SERV AG-Photon Solar 810 Wanamaker Ave Ontario... tariff filing per 35.13(a)(2)(iii: SGIA WDT SERV AG Photon Solar 4850 E Airport Dr Ontario Roof Top Solar...)(2)(iii: SGIA WDT SERV AG Photon Solar 1751-1753 S Point Ontario Roof Top Solar Project to...

  4. Photon Collider Physics with Real Photon Beams

    SciTech Connect

    Gronberg, J; Asztalos, S

    2005-11-03

    Photon-photon interactions have been an important probe into fundamental particle physics. Until recently, the only way to produce photon-photon collisions was parasitically in the collision of charged particles. Recent advances in short-pulse laser technology have made it possible to consider producing high intensity, tightly focused beams of real photons through Compton scattering. A linear e{sup +}e{sup -} collider could thus be transformed into a photon-photon collider with the addition of high power lasers. In this paper they show that it is possible to make a competitive photon-photon collider experiment using the currently mothballed Stanford Linear Collider. This would produce photon-photon collisions in the GeV energy range which would allow the discovery and study of exotic heavy mesons with spin states of zero and two.

  5. Solar Variability and the Near-Earth Environment: Mining Enhanced Low Dose Rate Sensitivity Data From the Microelectronics and Photonics Test Bed Space Experiment

    NASA Technical Reports Server (NTRS)

    Turflinger, T.; Schmeichel, W.; Krieg, J.; Titus, J.; Campbell, A.; Reeves, M.; Marshall (P.); Hardage, Donna (Technical Monitor)

    2004-01-01

    This effort is a detailed analysis of existing microelectronics and photonics test bed satellite data from one experiment, the bipolar test board, looking to improve our understanding of the enhanced low dose rate sensitivity (ELDRS) phenomenon. Over the past several years, extensive total dose irradiations of bipolar devices have demonstrated that many of these devices exhibited ELDRS. In sensitive bipolar transistors, ELDRS produced enhanced degradation of base current, resulting in enhanced gain degradation at dose rates <0.1 rd(Si)/s compared to similar transistors irradiated at dose rates >1 rd(Si)/s. This Technical Publication provides updated information about the test devices, the in-flight experiment, and both flight-and ground-based observations. Flight data are presented for the past 5 yr of the mission. These data are compared to ground-based data taken on devices from the same date code lots. Information about temperature fluctuations, power shutdowns, and other variables encountered during the space flight are documented.

  6. A comparative study of photon recycling effects in n{sup +}-p and p{sup +}-n InP solar cells with Bragg reflector

    SciTech Connect

    Yamamoto, A.; Kurizuka, M.; Murshid, Md.M.; Hashimoto, A.

    1997-12-31

    Numerical calculation of photon recycling (PR) effect has been carried out for n{sup +}-p and p{sup +}-n structure InP cells with Bragg reflector (BR). For both structures with a thin ({approx_gt}0.1 {micro}m) emitter, PR effects on photocurrent are scarcely observed. A large contribution of PR to photocurrent is found for an n{sup +}-p structure with a thick ({approx_gt}0.5 {micro}m) emitter although photocurrent itself is reduced. A p{sup +}-n structure with a similar configuration, on the other hand, shows very small PR effects. Such a difference in the magnitude of PR effects between both cell structures is brought by the difference in radiative and nonradiative lifetimes between n{sup +} and p{sup +} emitters. An increase in Voc is found for an n{sup +}-p cell with a thin ({approximately}2 {micro}m) base layer. As results of increases in photocurrent and Voc by PR, conversion efficiency of a n{sup +}-p cell is increased by about 3%. For both cell structures, BR effects are observed for a base thickness less than about 3 {micro}m. The effects are not due to the trapping of reemitted light but the trapping of incident light.

  7. Robust Ag nanoplate ink for flexible electronics packaging

    NASA Astrophysics Data System (ADS)

    Li, Ruo-Zhou; Hu, Anming; Bridges, Denzel; Zhang, Tong; Oakes, Ken D.; Peng, Rui; Tumuluri, Uma; Wu, Zili; Feng, Zhili

    2015-04-01

    Nanoinks are currently a topic of heightened interest with respect to low temperature bonding processes and printable electronics. We have developed an innovative polyvinylpyrrolidone (PVP)-stabilized Ag nanoplate ink amenable to very strong low temperature packaging, and investigated the relationship between bonding strength and electrical conductivity post-bonding. PVP shell plastic deformations observed in failure microcracks with the formation of PVP nanofibers, revealed bonding strength at low temperatures (<250 °C) was primarily due to adhesive bonding. It is found that, utilizing photonic sintering, ~70 °C reduction of transformation temperature from adhesive to metallic bonding was achieved compared to that of thermal sintering. A numerical simulation was developed to better understand the influences of the light-induced heat generation, which demonstrated near-infrared light can facilitate sintering. Bonding strengths of 27 MPa were achieved at room temperatures, and 29.4 MPa at 210 °C with photonic sintering. Moreover, the anisotropic resistivity was observed with different thermal dependences. These results demonstrate Ag nanoplate inks have potential for low temperature 3D interconnections in lead-free microcircuits, flexible electronic packaging, and diverse sensing applications.Nanoinks are currently a topic of heightened interest with respect to low temperature bonding processes and printable electronics. We have developed an innovative polyvinylpyrrolidone (PVP)-stabilized Ag nanoplate ink amenable to very strong low temperature packaging, and investigated the relationship between bonding strength and electrical conductivity post-bonding. PVP shell plastic deformations observed in failure microcracks with the formation of PVP nanofibers, revealed bonding strength at low temperatures (<250 °C) was primarily due to adhesive bonding. It is found that, utilizing photonic sintering, ~70 °C reduction of transformation temperature from adhesive to

  8. Photoemission from Shockley surface state on Ag(111)

    NASA Astrophysics Data System (ADS)

    Karkare, Siddharth; Wan, Weishi; Feng, Jun; Padmore, Howard

    We present measurements of quantum yield and transverse momentum distributions of electrons emitted from the Shockley surface state on Ag(111) surface using near threshold photons. Our measurements shed light on the validity of the conservation of transverse momentum during photoemission when the kinetic energy of electrons is less than 0.1 eV. We also develop a one-step photoemission model that quantitatively explains photoemission from single crystal metal surfaces. This model accurately calculates the dependence of the electron yield on the angle of incidence and the polarization of incident light (vectorial photoelectric effect). We show excellent agreement between the measured and calculated photoemission properties of the Ag(111) surface. Our measurements show that Ag(111) surface can act as an excellent electron source for several applications like Free Electron Lasers and Ultra-fast Electron Diffraction.

  9. Integrated photonics

    NASA Astrophysics Data System (ADS)

    Gondarenko, Alexander A.

    In 1958 the first integrated circuit was demonstrated to combine transistors, resistors, and capacitors [36]. To this date fabrication technology has been driven by the growing demand for monolithically constructed, densely packed electronic components. The exponentially shrinking device size decreased the feature dimensions from 10 microns to 32 nm and grew transistor count from 2,300 to over 2,000,000,000 in Intel's 4004 and Intel Kentsfield XE microprocessors. The benefits of micro- and nano-fabrication was not limited to just computer chips. MEMs, spintronic, microfluidics, and integrated photonics were all made possible by the ever expanding ability to form complex geometries, on a wide variety of materials, on a micron and submicron scale. This dissertation is part of an effort to design and fabricate novel integrated photonic devices compatible with standard electron beam and photo lithography and utilize a readily available material base. We aim to create devices with a decreased footprint on a chip and operate in the infrared, visible, and UV spectra. We present two general sections, the first is a theoretical effort to find the fundamental design geometries for a variety of optical problems. The second section is an experimental demonstration of techniques and devices for novel optical phenomena in an integrated package. In the theoretical section we develop and apply computational evolutionary algorithms to explore problems of light confinement, coupling, and guiding in two and three dimensional device geometries. Our general aim is to find a global limit to optimal device geometry and performance given a set of constrains. Experimentally, we demonstrate an efficient design and a fabrication process for a short development cycle of photonic devices. For the design part of the workflow, we develop a computational approach to explore device geometries with minimum initial assumptions for a variety of photonic problems. For the fabrication part of the

  10. Photonic crystal: energy-related applications

    SciTech Connect

    Ye, Zhuo; Park, Joong-Mok; Constant, Kristen; Kim, Tae-Geun; Ho, Kai-Ming

    2012-06-08

    We review recent work on photonic-crystal fabrication using soft-lithography techniques. We consider applications of the resulting structures in energy-related areas such as lighting and solar-energy harvesting. In general, our aim is to introduce the reader to the concepts of photonic crystals, describe their history, development, and fabrication techniques and discuss a selection of energy-related applications.

  11. Computational Photonics

    NASA Astrophysics Data System (ADS)

    Wartak, Marek S.

    2013-01-01

    1. Introduction; 2. Basic facts from optics; 3. Basic facts from electromagnetism; 4. Slab waveguides; 5. Linear optical fibre and signal degradation; 6. Propagation of linear pulses; 7. Optical sources; 8. Optical amplifiers and EDFA; 9. Semiconductor optical amplifiers (SOA); 10. Optical receivers; 11. Finite difference time domain (FDTD) formulation; 12. Solar cells; 13. Metamaterials; Appendices; Index.

  12. Integrated plasmonic and upconversion starlike Y2O3:Er/Au@TiO2 composite for enhanced photon harvesting in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Meng, Fanli; Luo, Yi; Zhou, Yali; Zhang, Jinwen; Zheng, Yanzhen; Cao, Guozhong; Tao, Xia

    2016-06-01

    A plasmon-enhanced upconversion composite Y2O3:Er/Au@TiO2 (SYE/A@T) with a three-dimensional starlike morphology is prepared and then mixed with submicron TiO2 (200 nm) to form a multifunctional scattering layer in TiO2-based dye-sensitized solar cells (DSSCs). In such starlike micronsized upconverter, Au nanoparticle-assisted plasmon effect can intensify the upconversion emission of Y2O3:Er, and simultaneously TiO2 coating can improve the charge transport within SYE/A@T. Therefore, the SYE/A@T shows extended light-absorbing range to near-infrared region and improved light-scattering ability, leading to an improved photovoltaic performance of DSSCs. With the optimum mixing ratio, a conversion efficiency of 8.62% is attained, which is a significant improvement of 27.6% compared with the cell without adding SYE/A@T. Our work provides a feasible strategy to prepare an upconversion composite with plasmon-enhanced emission and enable this composite to accommodate the DSSCs system and improve the conversion efficiency of DSSCs.

  13. A simple modification of near-infrared photon-to-electron response with fluorescence resonance energy transfer for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Liang; Yang, Yulin; Fan, Ruiqing; Jiang, Yanxia; Wei, Liguo; Shi, Yan; Yu, Jia; Chen, Shuo; Wang, Ping; Yang, Bin; Cao, Wenwu

    2014-10-01

    Upconversion (UC) Er, Yb-YF3 is introduced into dye-sensitized solar cells (DSSC) through a simple method to investigate the effect of UC particles in photoanode. The utilization of UC phosphor can significantly improve the photocurrent of the cells under both infrared irradiation and sunlight. Fluorescence resonance energy transfer (FRET) and luminescence-mediated energy transfer between UC-YF3 and N719 dye are explored as the main contribution that UC-YF3 made to DSSC. With the multi-efforts of UC-YF3, power conversion efficiency (PCE) of DSSC is improved from 5.18% to 6.22%. Besides, Electron transfer between UC-YF3 and TiO2 is found after sintered at 450 °C, and the PCE value of DSSC is improved further (5.34% → 6.76%). In addition, we explore that UC-YF3 can serve as a scattering material to increase the light absorption capability of the cells and increase the photocurrent of the cells under simulated sunlight irradiation.

  14. Freeze-dried PVP-Ag+ precursors to novel AgBr/AgCl-Ag hybrid nanocrystals for visible-light-driven photodegradation of organic pollutants

    NASA Astrophysics Data System (ADS)

    Chen, Deliang; Chen, Qianqian; Zhang, Wenjie; Ge, Lianfang; Shao, Gang; Fan, Bingbing; Lu, Hongxia; Zhang, Rui; Yang, Daoyuan; Shao, Guosheng

    2015-04-01

    AgBr/AgCl-Ag nanocrystals with various molar Br-to-Ag ratios (RBr/Ag = 0, 1/3, 1/2, 2/3, 1) and different photoreduction times (0-20 min) were synthesized via stepwise liquid-solid reactions using the freeze-dried PVP-Ag+ hybrid as the Ag source, followed by a photoreduction reaction. The AgBr/AgCl-Ag7.5(1:2) nanocrystals obtained take on a spherical morphology with a particle-size range of 58 ± 15 nm. The photocatalytic performance of AgBr/AgCl-Ag nanocrystals was evaluated by photodegrading organic dyes, 4-chlorophenol and isopropanol under artificial visible light (λ ⩾ 420 nm, 100 mW cm-2). For the decomposition of rhodamine B, the AgBr/AgCl-Ag7.5(1:2) nanocrystals has a photodegradation rate of ∼0.87 min-1, ∼159 times higher than that (∼0.0054 min-1) of TiO2 (P25), whereas the AgCl-Ag and AgBr-Ag nanocrystals have photodegradation rates of 0.35 min-1 and 0.45 min-1, respectively. The efficient separation of photogenerated electron-hole pairs in the ternary system consisting of AgBr, AgCl and Ag species plays a key role in the enhancement of photocatalytic performance.

  15. Ag K- and L3-edge XAFS study on Ag species in Ag/Ga2O3 photocatalysts

    NASA Astrophysics Data System (ADS)

    Yamamoto, M.; Yoshida, T.; Yamamoto, N.; Nomoto, T.; Yamamoto, A.; Yoshida, H.; Yagi, S.

    2016-05-01

    Ag loaded Ga2O3 (Ag/Ga2O3) shows photocatalytic activity for reduction of CO2 with water. Ag L3-edge XANES and K-edge EXAFS spectra were measured for various Ag/Ga2O3 samples, which suggested that structural and chemical states of Ag species varied with the loading amount of Ag and the preparation method. The Ag species were metallic Ag particles with an AgGaO2-like interface structure in the sample with high loading amount of Ag while predominantly Ag metal clusters in the sample with low loading amount of Ag. The XANES feature just above the edge represented the interaction between the Ag species and the Ga2O3 surface, showing that the Ag metal clusters had more electrons in the d-orbitals by interacting with the Ga2O3 surface, which would contribute the high photocatalytic activity.

  16. AGS experiments -- 1995, 1996 and 1997

    SciTech Connect

    Depken, J.C.; Presti, P.L.

    1997-12-01

    This report contains (1) FY 1995 AGS schedule as run; (2) FY 1996 AGS schedule as run; (3) FY 1997 AGS schedule as run; (4) FY 1998--1999 AGS schedule (proposed); (5) AGS beams 1997; (6) AGS experimental area FY 1995 physics program; (7) AGS experimental area FY 1996 physics program; (8) AGS experimental area FY 1997 physics program; (9) AGS experimental area FY 1998--1999 physics program (proposed); (10) a listing of experiments by number; (11) two-page summaries of each experiment, in order by number; and (12) listing of publications of AGS experiments.

  17. AGS experiments -- 1991, 1992, 1993. Tenth edition

    SciTech Connect

    Depken, J.C.

    1994-04-01

    This report contains: (1) FY 1993 AGS schedule as run; (2) FY 1994--95 AGS schedule; (3) AGS experiments {ge} FY 1993 (as of 30 March 1994); (4) AGS beams 1993; (5) AGS experimental area FY 1991 physics program; (6) AGS experimental area FY 1992 physics program; (7) AGS experimental area FY 1993 physics program; (8) AGS experimental area FY 1994 physics program (planned); (9) a listing of experiments by number; (10) two-page summaries of each experiment; (11) listing of publications of AGS experiments; and (12) listing of AGS experiments.

  18. Selectively transparent and conducting photonic crystal rear-contacts for thin-film silicon-based building integrated photovoltaics.

    PubMed

    O'Brien, P G; Chutinan, A; Mahtani, P; Leong, K; Ozin, G A; Kherani, N P

    2011-08-29

    Wave-optics analysis is performed to show that selectively transparent and conducting photonic crystals (STCPCs) can be utilized as rear contacts to enhance the performance of building-integrated photovoltaics (BIPV). For instance, the current generated in an a-Si:H cell with an STCPC functioning as its rear contact is comparable to that of a similar cell with an optimized ZnO/Ag rear contact. However, the solar lumens (~3.5 klm/m2) and power (~430W/m2) transmitted through the cell with the STCPC rear contact can potentially provide indoor heating and lighting, respectively. Moreover, experimental results show that STCPC rear contacts could be used to control the color temperature of light transmitted through BIPV panels. PMID:21935064

  19. Selectively transparent and conducting photonic crystal rear-contacts for thin-film silicon-based building integrated photovoltaics

    NASA Astrophysics Data System (ADS)

    O'Brien, P. G.; Chutinan, A.; Mahtani, P.; Leong, K.; Ozin, G. A.; Kherani, N. P.

    2011-08-01

    Wave-optics analysis is performed to show that selectively transparent and conducting photonic crystals (STCPCs) can be utilized as rear contacts to enhance the performance of building-integrated photovoltaics (BIPV). For instance, the current generated in an a-Si:H cell with an STCPC functioning as its rear contact is comparable to that of a similar cell with an optimized ZnO/Ag rear contact. However, the solar lumens (~3.5 klm/m2) and power (~430W/m2) transmitted through the cell with the STCPC rear contact can potentially provide indoor heating and lighting, respectively. Moreover, experimental results show that STCPC rear contacts could be used to control the color temperature of light transmitted through BIPV panels.

  20. Destabilization of Ag nanoislands on Ag(100) by adsorbed sulfur

    SciTech Connect

    Shen, Mingmin; Russell, Selena M.; Liu, Da-Jiang; Thiel, Patricia A.

    2011-10-17

    Sulfur accelerates coarsening of Ag nanoislands on Ag(100) at 300 K, and this effect is enhanced with increasing sulfur coverage over a range spanning a few hundredths of a monolayer, to nearly 0.25 monolayers. We propose that acceleration of coarsening in this system is tied to the formation of AgS{sub 2} clusters primarily at step edges. These clusters can transport Ag more efficiently than can Ag adatoms (due to a lower diffusion barrier and comparable formation energy). The mobility of isolated sulfur on Ag(100) is very low so that formation of the complex is kinetically limited at low sulfur coverages, and thus enhancement is minimal. However, higher sulfur coverages force the population of sites adjacent to step edges, so that formation of the cluster is no longer limited by diffusion of sulfur across terraces. Sulfur exerts a much weaker effect on the rate of coarsening on Ag(100) than it does on Ag(111). This is consistent with theory, which shows that the difference between the total energy barrier for coarsening with and without sulfur is also much smaller on Ag(100) than on Ag(111).

  1. Photonic Nanojets

    PubMed Central

    Heifetz, Alexander; Kong, Soon-Cheol; Sahakian, Alan V.; Taflove, Allen; Backman, Vadim

    2009-01-01

    This paper reviews the substantial body of literature emerging since 2004 concerning photonic nanojets. The photonic nanojet is a narrow, high-intensity, non-evanescent light beam that can propagate over a distance longer than the wavelength λ after emerging from the shadow-side surface of an illuminated lossless dielectric microcylinder or microsphere of diameter larger than λ. The nanojet’s minimum beamwidth can be smaller than the classical diffraction limit, in fact as small as ~λ/3 for microspheres. It is a nonresonant phenomenon appearing for a wide range of diameters of the microcylinder or microsphere if the refractive index contrast relative to the background is less than about 2:1. Importantly, inserting within a nanojet a nanoparticle of diameter dν perturbs the far-field backscattered power of the illuminated microsphere by an amount that varies as dν3 for a fixed λ. This perturbation is much slower than the dν6 dependence of Rayleigh scattering for the same nanoparticle, if isolated. This leads to a situation where, for example, the measured far-field backscattered power of a 3-μm diameter microsphere could double if a 30-nm diameter nanoparticle were inserted into the nanojet emerging from the microsphere, despite the nanoparticle having only 1/10,000th the cross-section area of the microsphere. In effect, the nanojet serves to project the presence of the nanoparticle to the far field. These properties combine to afford potentially important applications of photonic nanojets for detecting and manipulating nanoscale objects, subdiffraction-resolution nanopatterning and nanolithography, low-loss waveguiding, and ultrahigh-density optical storage. PMID:19946614

  2. Photonic Flash Sintering of Ink-Jet-Printed Back Electrodes for Organic Photovoltaic Applications.

    PubMed

    Polino, Giuseppina; Shanmugam, Santhosh; Bex, Guy J P; Abbel, Robert; Brunetti, Francesca; Di Carlo, Aldo; Andriessen, Ronn; Galagan, Yulia

    2016-01-27

    A study of the photonic flash sintering of a silver nanoparticle ink printed as the back electrode for organic solar cells is presented. A number of sintering settings with different intensities and pulse durations have been tested on both full-area and grid-based silver electrodes, using the complete emission spectrum of the flash lamps from UV-A to NIR. However, none of these settings was able to produce functional devices with performances comparable to those of reference cells prepared using thermally sintered ink. Different degradation mechanisms were detected in the devices with a flash-sintered back electrode. The P3HT:PCBM photoactive layer appears to be highly heat-sensitive and turned out to be severely damaged by the high temperatures generated in the silver layer during the sintering. In addition, UV-induced photochemical degradation of the functional materials was identified as another possible source of performance deterioration in the devices with grid-based electrodes. Reducing the light intensity does not provide a proper solution because in this case the Ag electrode is not sintered sufficiently. For both types of devices, with full-area and grid-based electrodes, these problems could be solved by excluding the short wavelength contribution from the flash light spectrum using a filter. Optimized sintering parameters allowed manufacture of OPV devices with performance equal to those of the reference devices. Photonic flash sintering of the top electrode in organic solar cells was demonstrated for the first time. It reveals the great potential of this sintering method for the future roll-to-roll manufacturing of organic solar cells from solution. PMID:26704172

  3. Photon calorimeter

    DOEpatents

    Chow, Tze-Show

    1988-04-22

    A photon calorimeter is provided that comprises a laminar substrate that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating, that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions, are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly. 4 figs.

  4. Photon Calorimeter

    DOEpatents

    Chow, Tze-Show

    1989-01-01

    A photon calorimeter (20, 40) is provided that comprises a laminar substrate (10, 22, 42) that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating (28, 48, 52), that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions (30, 50, 54) are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly.

  5. Ferrofluid Photonic Dipole Contours

    NASA Astrophysics Data System (ADS)

    Snyder, Michael; Frederick, Jonathan

    2008-03-01

    Understanding magnetic fields is important to facilitate magnetic applications in diverse fields in industry, commerce, and space exploration to name a few. Large electromagnets can move heavy loads of metal. Magnetic materials attached to credit cards allow for fast, accurate business transactions. And the Earth's magnetic field gives us the colorful auroras observed near the north and south poles. Magnetic fields are not visible, and therefore often hard to understand or characterize. This investigation describes and demonstrates a novel technique for the visualization of magnetic fields. Two ferrofluid Hele-Shaw cells have been constructed to facilitate the imaging of magnetic field lines [1,2,3,4]. We deduce that magnetically induced photonic band gap arrays similar to electrostatic liquid crystal operation are responsible for the photographed images and seek to mathematically prove the images are of exact dipole nature. We also note by comparison that our photographs are very similar to solar magnetic Heliosphere photographs.

  6. Perovskite photonic sources

    NASA Astrophysics Data System (ADS)

    Sutherland, Brandon R.; Sargent, Edward H.

    2016-05-01

    The field of solution-processed semiconductors has made great strides; however, it has yet to enable electrically driven lasers. To achieve this goal, improved materials are required that combine efficient (>50% quantum yield) radiative recombination under high injection, large and balanced charge-carrier mobilities in excess of 10 cm2 V-1 s-1, free-carrier densities greater than 1017 cm-3 and gain coefficients exceeding 104 cm-1. Solid-state perovskites are -- in addition to galvanizing the field of solar electricity -- showing great promise in photonic sources, and may be the answer to realizing solution-cast laser diodes. Here, we discuss the properties of perovskites that benefit light emission, review recent progress in perovskite electroluminescent diodes and optically pumped lasers, and examine the remaining challenges in achieving continuous-wave and electrically driven lasing.

  7. AGS preinjector improvement

    SciTech Connect

    Alessi, J.G.; Brennan, J.M.; Brown, H.N.; Brodowski, J.; Gough, R.; Kponou, A.; Prelec, K.; Staples, J.; Tanabe, J.; Witkover, R.

    1987-01-01

    In 1984, a polarized H/sup -/ source was installed to permit the acceleration of polarized protons in the AGS, using a low current, 750 keV RFQ Linear Accelerator as the preinjector. This RFQ was designed by LANL and has proved to be quite satisfactory and reliable. In order to improve the reliability and simplify maintenance of the overall AGS operations, it has been decided to replace one of the two 750 keV Cockcroft-Waltons (C-W) with an RFQ. The design of a new high current RFQ has been carried out by LBL and is also being constructed there. This paper describes the preinjector improvement project, centered around that RFQ, which is underway at BNL.

  8. Solar Sail Propulsion for Interplanetary Cubesats

    NASA Technical Reports Server (NTRS)

    Johnson, Les; Sobey, Alex; Sykes, Kevin

    2015-01-01

    NASA is developing two small satellite missions as part of the Advanced Exploration Systems (AES) Program, both of which will use a solar sail to enable their scientific objectives. Solar sails use sunlight to propel vehicles through space by reflecting solar photons from a large, mirror-like sail made of a lightweight, highly reflective material. This continuous photon pressure provides propellantless thrust, allowing for very high (Delta)V maneuvers on long-duration, deep space exploration. Since reflected light produces thrust, solar sails require no onboard propellant. Solar sail technology is rapidly maturing for space propulsion applications within NASA and around the world.

  9. The isotopic composition and concentration of AG in iron meteorites and the origin of exotic silver

    NASA Astrophysics Data System (ADS)

    Kaiser, T.; Wasserburg, G. J.

    1983-01-01

    The isotopic composition of Ag and the concentration of Ag and Pd have been determined in Canyon Diablo (IA), Grant (IIIB), Hoba, Santa Clara, Tlacotepec and Warburton Range (IVB), Piñon and Deep Springs (anom.). Troilite from Grant and Santa Clara have also been analyzed. All of these meteorites, with the exception of Canyon Diablo, give 107Ag/109Ag in the metal phase that is greater than the terrestrial value with the enrichments of 107Ag ranging from ≡2% to 212%. These data show that Ag of anomalous isotopic composition is common to all IVB and anomalous meteorites. The results on Grant suggest that the anomalies may be widespread including more common meteorite groups. There is a general correlation of 107Ag/109Ag with Pd/Ag except for the data from FeS of Santa Clara. The data suggest that Ag in Santa Clara and possibly other IVB meteorites is made up of almost pure 107Ag produced from 107Pd decay and 109Ag produced by nuclear reactions with only a small amount of "normal" Ag. This indicates an intense energetic particle bombardment history in the early solar system (≡1020 p/m2) which occurred after the formation of small planetary bodies. The authors infer that a T-Tauri activity by the early sun contributed to some late stage "nucleosynthesis" and the heating of a dust cloud. In addition, implications on the early thermal evolution of iron meteorites are presented based on 107Pd decay and models of the cooling history.

  10. Tevatron direct photon results.

    SciTech Connect

    Kuhlmann, S.

    1999-09-21

    Tevatron direct photon results since DIS98 are reviewed. Two new CDF measurements are discussed, the Run Ib inclusive photon cross section and the photon + Muon cross section. Comparisons with the latest NLO QCD calculations are presented.

  11. The Continuing Slow Decline of AG Pegasi

    NASA Astrophysics Data System (ADS)

    Kenyon, Scott J.; Proga, Daniel; Keyes, Charles D.

    2001-07-01

    We analyze optical and ultraviolet observations of the symbiotic binary AG Pegasi acquired during 1992-1997. The bolometric luminosity of the hot component declined by a factor of 2-3 from 1980-1985 to 1997. Since 1992, the effective temperature of the hot component may have declined by 10%-20%, but this decline is comparable to the measurement errors. Optical observations of Hβ and He I emission show a clear illumination effect, where high-energy photons from the hot component ionize the outer atmosphere of the red giant. Simple illumination models generally account for the magnitude of the optical and ultraviolet emission-line fluxes. High-ionization emission lines-[Ne V], [Mg V], and [Fe VII]-suggest mechanical heating in the outer portions of the photoionized red giant wind. This emission probably originates in a low-density region ~30-300 AU from the central binary.

  12. Resonance formation in photon-photon collisions

    SciTech Connect

    Gidal, G.

    1988-08-01

    Recent experimental progress on resonance formation in photon-photon collisions is reviewed with particular emphasis on the pseudoscalar and tensor nonents and on the ..gamma gamma..* production of spin-one resonances. 37 refs., 17 figs., 5 tabs.

  13. Physics at high energy photon photon colliders

    SciTech Connect

    Chanowitz, M.S.

    1994-06-01

    I review the physic prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking.

  14. Photocatalysis: Plasmonic solar desalination

    NASA Astrophysics Data System (ADS)

    Liu, Tianyu; Li, Yat

    2016-06-01

    The sustainability of many existing desalination technologies is questionable. Plasmon-mediated solar desalination has now been demonstrated for the first time, using an aluminium structure that absorbs photons spanning the 200 nm to 2,500 nm wavelength range, and is both cheap and 'clean'.

  15. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

    Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

  16. Ag-Air Service

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Econ, Inc.'s agricultural aerial application, "ag-air," involves more than 10,000 aircraft spreading insecticides, herbicides, fertilizer, seed and other materials over millions of acres of farmland. Difficult for an operator to estimate costs accurately and decide what to charge or which airplane can handle which assignment most efficiently. Computerized service was designed to improve business efficiency in choice of aircraft and determination of charge rates based on realistic operating cost data. Each subscriber fills out a detailed form which pertains to his needs and then receives a custom-tailored computer printout best suited to his particular business mix.

  17. Exclusive photon-photon processes

    SciTech Connect

    Brodsky, S.J.

    1997-07-01

    Exclusive gamma gamma right arrow hadron pairs are among the most fundamental processes in QCD, providing a detailed examination of Compton scattering in the crossed channel. In the high momentum transfer domain (s, t, large, Theta cm for t/s fixed), these processes can be computed from first principles in QCD, yielding important information on the nature of the QCD coupling data and the form of hadron distribution amplitudes. Similarly, the transition form factors gamma star gamma, gamma star gamma right arrow pi(o), Eta (0), Eta`, Eta(c)... provide rigorous tests of QCD and definitive determinations of the meson distribution amplitudes Phi H(x,Q). We show that the assumption of a frozen coupling at low momentum transfers can explain the observed scaling of two-photon exclusive processes.

  18. Photon recycling and Shockley's diode equation

    NASA Astrophysics Data System (ADS)

    Martí, A.; Balenzategui, J. L.; Reyna, R. F.

    1997-10-01

    The Shockley's diode equation predicts a current-voltage characteristic different from that used by Shockley and Queisser to compute the limiting efficiency of photovoltaic energy conversion under the assumptions of the detailed balance theory. The reasons for such discrepancy are discussed being the neglect of photon recycling effects in Shockley's diode equation the main cause. This interpretation is crucial to understand the fundamentals on which the computation of the limiting efficiency of solar cells is based. Without photon recycling effects, it can be concluded that the limiting efficiency (one sun) of a gallium arsenide solar cell is 26.8% (with the sun assumed as blackbody at 6000 K) while the true figure is 30.7%, 38.7% as long as the angle of emission of photons from the cell is fully restricted.

  19. Bimetallic Pt-Ag and Pd-Ag nanoparticles

    SciTech Connect

    Lahiri, Debdutta; Bunker, Bruce; Mishra, Bhoopesh; Zhang, Zhenyuan; Meisel, Dan; Doudna, C. M.; Bertino, M. F.; Blum, Frank D.; Tokuhiro, A. T.; Chattopadhyay, Soma; Shibata, Tomohiro; Terry, Jeff

    2005-04-19

    We report studies of bimetallic nanoparticles with 15%–16% atomic crystal parameters size mismatch. The degree of alloying was also probed in a 2-nm Pt core ssmallest attainable core sized of Pt–Ag nanoparticles scompletely immiscible in bulkd and 20-nm-diameter Pd–Ag nanowires scompletely miscible in bulkd. Particles were synthesized radiolytically, and depending on the initial parameters, they assume spherical or cylindrical snanowired morphologies. In all cases, the metals are seen to follow their bulk alloying characteristics. Also, Pt and Ag segregate in both spherical and wire forms, which indicates that strain due to crystallographic mismatch overcomes the excess surface free energy in the small particles. The Pd–Ag nanowires alloy similar to previously reported spherical Pd–Ag particles of similar diameter and composition

  20. Bimetallic Pt-Ag and Pd-Ag nanoparticles

    SciTech Connect

    Lahiri, Debdutta; Bunker, Bruce; Mishra, Bhoopesh; Zhang, Zhenyuan; Meisel, Dan; Doudna, C.M.; Bertino, M. F.; Blum, Frank D.; Tokuhiro, A.T.; Chattopadhyay, Soma; Shibata, Tomohiro; Terry, Jeff

    2005-05-01

    We report studies of bimetallic nanoparticles with 15%-16% atomic crystal parameters size mismatch. The degree of alloying was probed in a 2-nm Pt core (smallest attainable core size) of Pt-Ag nanoparticles (completely immiscible in bulk) and 20-nm-diameter Pd-Ag nanowires (completely miscible in bulk). Particles were synthesized radiolytically, and depending on the initial parameters, they assume spherical or cylindrical (nanowire) morphologies. In all cases, the metals are seen to follow their bulk alloying characteristics. Pt and Ag segregate in both spherical and wire forms, which indicates that strain due to crystallographic mismatch overcomes the excess surface free energy in the small particles. The Pd-Ag nanowires alloy similar to previously reported spherical Pd-Ag particles of similar diameter and composition.

  1. Photon-Photon Interactions via Rydberg Blockade

    SciTech Connect

    Gorshkov, Alexey V.; Otterbach, Johannes; Fleischhauer, Michael; Pohl, Thomas; Lukin, Mikhail D.

    2011-09-23

    We develop the theory of light propagation under the conditions of electromagnetically induced transparency in systems involving strongly interacting Rydberg states. Taking into account the quantum nature and the spatial propagation of light, we analyze interactions involving few-photon pulses. We show that this system can be used for the generation of nonclassical states of light including trains of single photons with an avoided volume between them, for implementing photon-photon gates, as well as for studying many-body phenomena with strongly correlated photons.

  2. Photon upconversion with directed emission.

    PubMed

    Börjesson, K; Rudquist, P; Gray, V; Moth-Poulsen, K

    2016-01-01

    Photon upconversion has the potential to increase the efficiency of single bandgap solar cells beyond the Shockley Queisser limit. Efficient light management is an important point in this context. Here we demonstrate that the direction of upconverted emission can be controlled in a reversible way, by embedding anthracene derivatives together with palladium porphyrin in a liquid crystalline matrix. The system is employed in a triplet-triplet annihilation photon upconversion scheme demonstrating controlled switching of directional anti Stokes emission. Using this approach an emission ratio of 0.37 between the axial and longitudinal emission directions and a directivity of 1.52 is achieved, reasonably close to the theoretical maximal value of 2 obtained from a perfectly oriented sample. The system can be switched for multiple cycles without any visible degradation and the speed of switching is only limited by the intrinsic rate of alignment of the liquid crystalline matrix. PMID:27573539

  3. What Is Ag-Ed?

    ERIC Educational Resources Information Center

    Lindley, Judy

    Ag-Ed is an agricultural education project aimed at upper primary students, held in conjunction with the Toowoomba Show (similar to a county fair) in Queensland, Australia. The program achieves its purpose of helping children understand the impact and relevance that agriculture has on their everyday lives through two components, an Ag-Ed day and a…

  4. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule ``as run``; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  5. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  6. Effects of Current-injection Firing with Ag Paste in a Boron Emitter.

    PubMed

    Kim, Chanseok; Choi, Jae-Wook; Choi, Sungjin; Kim, Soomin; Park, Hyomin; Song, Hee-eun; Yoon, Sam S; Huh, Joo-Youl; Kang, Yoonmook; Lee, Hae-Seok; Kim, Donghwan

    2016-01-01

    A high contact resistance for screen-printed contacts was observed when a conventional Ag paste was used on a boron emitter. The results of this study suggest that electron injection during firing is one of the processes that contribute to a lower contact resistance. Larger quantities of Ag precipitates formed upon electron injection into the boron emitter, which was confirmed by observing Ag crystallite or dendrite structures on the boron and by measuring the contact resistance between the boron emitter and the Ag bulk. The electron-injected sample had approximately 10000 times lower contact resistance than an untreated sample. The contact resistance of the electron-injected sample was 0.021 mΩ ∙ cm(2) under optimal conditions, which is lower than that of conventional p-type silicon solar cells. Thus, electron injection can effectively lower contact resistance when using Ag paste in n-type silicon solar cells. During the cooling in the firing process, dissolved Ag ions in the glass layer are formed as dendrites or crystallites/particles. The dendrites are formed earlier than others via electrochemical migration under electron injection conditions. Then, crystallites and particles are formed via a silicon etching reaction. Thus, Ag ions that are not formed as dendrites will form as crystallites or particles. PMID:26861828

  7. Effects of Current-injection Firing with Ag Paste in a Boron Emitter

    NASA Astrophysics Data System (ADS)

    Kim, Chanseok; Choi, Jae-Wook; Choi, Sungjin; Kim, Soomin; Park, Hyomin; Song, Hee-Eun; Yoon, Sam S.; Huh, Joo-Youl; Kang, Yoonmook; Lee, Hae-Seok; Kim, Donghwan

    2016-02-01

    A high contact resistance for screen-printed contacts was observed when a conventional Ag paste was used on a boron emitter. The results of this study suggest that electron injection during firing is one of the processes that contribute to a lower contact resistance. Larger quantities of Ag precipitates formed upon electron injection into the boron emitter, which was confirmed by observing Ag crystallite or dendrite structures on the boron and by measuring the contact resistance between the boron emitter and the Ag bulk. The electron-injected sample had approximately 10000 times lower contact resistance than an untreated sample. The contact resistance of the electron-injected sample was 0.021 mΩ•cm2 under optimal conditions, which is lower than that of conventional p-type silicon solar cells. Thus, electron injection can effectively lower contact resistance when using Ag paste in n-type silicon solar cells. During the cooling in the firing process, dissolved Ag ions in the glass layer are formed as dendrites or crystallites/particles. The dendrites are formed earlier than others via electrochemical migration under electron injection conditions. Then, crystallites and particles are formed via a silicon etching reaction. Thus, Ag ions that are not formed as dendrites will form as crystallites or particles.

  8. Effects of Current-injection Firing with Ag Paste in a Boron Emitter

    PubMed Central

    Kim, Chanseok; Choi, Jae-Wook; Choi, Sungjin; Kim, Soomin; Park, Hyomin; Song, Hee-eun; Yoon, Sam S.; Huh, Joo-Youl; Kang, Yoonmook; Lee, Hae-Seok; Kim, Donghwan

    2016-01-01

    A high contact resistance for screen-printed contacts was observed when a conventional Ag paste was used on a boron emitter. The results of this study suggest that electron injection during firing is one of the processes that contribute to a lower contact resistance. Larger quantities of Ag precipitates formed upon electron injection into the boron emitter, which was confirmed by observing Ag crystallite or dendrite structures on the boron and by measuring the contact resistance between the boron emitter and the Ag bulk. The electron-injected sample had approximately 10000 times lower contact resistance than an untreated sample. The contact resistance of the electron-injected sample was 0.021 mΩ∙cm2 under optimal conditions, which is lower than that of conventional p-type silicon solar cells. Thus, electron injection can effectively lower contact resistance when using Ag paste in n-type silicon solar cells. During the cooling in the firing process, dissolved Ag ions in the glass layer are formed as dendrites or crystallites/particles. The dendrites are formed earlier than others via electrochemical migration under electron injection conditions. Then, crystallites and particles are formed via a silicon etching reaction. Thus, Ag ions that are not formed as dendrites will form as crystallites or particles. PMID:26861828

  9. Structure modeling and growing AgClхBr1-х, Ag1-xTlxBr1-xIx, and Ag1-xTlxClyIzBr1-y-z crystals for infrared fiber optics

    NASA Astrophysics Data System (ADS)

    Korsakov, Alexandr; Zhukova, Liya; Korsakova, Elena; Zharikov, Evgenii

    2014-01-01

    In this paper we describe the aggregate technology of producing variable composition crystals, based on the solid solutions of silver and Tl+-doped halides for creating infrared photonic crystal fibers in the spectral range of 2-40 μm by extruding, we also produce all the necessary equipment. We specified the minimum melting point position for the AgCl-AgBr phase diagram. We also investigated the fundamental physical properties of new crystals and fibers: transmission losses, transmission range, refraction index, hardness, and density.

  10. Plasmonic effect of spray-deposited Au nanoparticles on the performance of inverted organic solar cells.

    PubMed

    Chaturvedi, Neha; Swami, Sanjay Kumar; Dutta, Viresh

    2014-09-21

    Gold nanoparticles with varying sizes were prepared by the spray process under an electric field (DC voltages of 0 V and 1 kV applied to the nozzle) for studying their role in inverted organic solar cells (ITO/Au/ZnO/P3HT:PCBM/Ag). The application of electric field during the spray process resulted in a smaller size (35 nm as compared to 70 nm without the electric field) of the nanoparticles with more uniform distribution. This gave rise to a difference in the surface plasmon resonance (SPR) effect created by the gold nanoparticles (Au NPs), which then affected the solar cell performance. The photovoltaic performances of plasmonic inverted organic solar cells (ITO/Au/ZnO/P3HT:PCBM/Ag) using spray-deposited Au and ZnO layers (both at 1 kV) showed improved efficiency. Fast exciton quenching in the P3HT:PCBM layer was achieved by using a spray-deposited Au layer in between ITO and ZnO layers. The absorption spectra and internal power conversion efficiency (IPCE) curve showed that the Au nanoparticles provide significant plasmonic broadband light absorption enhancement which resulted in the enhancement of the JSC value. Maximum efficiency of 3.6% was achieved for the inverted organic solar cell (IOSC) with an exceptionally high short circuit current density of ∼15 mA cm(-2) which is due to the additional photon absorption and the corresponding increase observed in the IPCE spectrum. The spray technique can be easily applied for the direct formation of Au nanoparticles in the fabrication of IOSC with improved performance over a large area. PMID:25100621

  11. THE AGS ELECTROSTATIC SEPTUM.

    SciTech Connect

    HOCK,J.RUSSO,T.GLEN,J.BROWN,K.

    2003-05-12

    The previous slow beam extraction electro static septum in the AGS was designed in 1981. Research documented at the Fermi Laboratory was used as the base line for this design. The septum consisted of a ground plane of .002 inch diameter wire tungsten-rhenium alloy (75%W 25%Re) with a hollow welded titanium cathode assembly. The vacuum chamber is stationary and the septum is moved with a pair of high vacuum linear feed throughs. After years of beam time, the frequency of failures increased. The vacuum system design was poor by today's standards and resulted in long pump down times after repairs. The failures ranged from broken septum wires to a twisted cathode. In addition to the failures, the mechanical drive system had too much backlash, making the operating position difficult to repeat. The new septum needed to address all of these issues in order to become a more reliable septum.

  12. EPIDAUROS Biotechnologie AG.

    PubMed

    Arnold, Hans-Peter; Kluge, Peter; Mauch, Simon

    2005-07-01

    EPIDAUROS Biotechnologie AG is a leading provider of pharmacogenetic consulting, genotyping and research services to the international pharmaceutical and biotechnology industries, contract research organizations and healthcare providers. The company's mission is to improve safety, efficacy and predictability in drug development and drug therapy. EPIDAUROS determines its customers' needs in the field of pharmacogenetics using an in-depth consultancy process. The development and conduct of genotyping assays for drug-metabolizing enzymes, drug transporters and drug targets (for example, receptors)--all performed under stringent quality standards--are a major activity at EPIDAUROS. The company offers its research services to academic and industrial partners for the development of innovative diagnostic solutions by using its intellectual property. PMID:16014003

  13. Photon degradation effects in terrestrial solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.; Brandhorst, H. W., Jr.; Broder, J. D.; Hart, R. E.; Lamneck, S. H.

    1978-01-01

    Reduction in cell output was observed in N(+)/P cells upon exposure to illumination or upon the application of a sufficiently high forward bias. Conversely, an enhancement in output was observed when P(+)/N cells were illuminated. Investigations performed on N(+)/P cells indicated that a recombination center located at E sub c - 0.37 eV in the forbidden band was responsible for the loss in output. The center was electrically inactive in its ground state but was activated either by raising the minority carrier quasi-Fermi level sufficiently close to the latent center energy level in the band gap, or by direct excitation of electrons from the valence band to the latent center level. The center was identified as a complex of a lattice defect and a silver atom or cluster of atoms.

  14. AgH, Ag/sub 2/, and AgO revisited: Basis set extensions

    SciTech Connect

    Martin, R.L.

    1987-05-01

    An extended basis set has been developed for Ag which significantly improves the agreement between theoretical and experimental spectroscopic parameters for AgH, AgO, and Ag/sub 2/. The major improvement comes about as a result of the improved treatment of electron correlation in the Ag d shell upon the introduction of f functions. Their inclusion produces very slight differences at the SCF level, but significant reductions in r/sub e/ and increases in ..omega../sub e/ and D/sub e/ in the Mo-dash-barller--Plesset perturbation theory expansion. At the MP4(SDTQ) level, typical results are 0.02 A too long for r/sub e/, 4% too low for ..omega../sub e/, and 10 kcal too small for D/sub e/. From a pragmatic standpoint, MP2 give results very similar to this at a much reduced level of effort.

  15. ZnO/Ag nanowires composite film ultraviolet photoconductive detector

    NASA Astrophysics Data System (ADS)

    Guodong, Yan; Minqiang, Wang; Zhi, Yang

    2015-08-01

    ZnO/Ag nanowires (NWs) film ultraviolet (UV) detector was fabricated by a simple and low-cost solution-processed method. In order to prepare this device, Ag NWs network was first spin-coated on glass substrate as a transparent conducting electrode, then ZnO NWs arrays were grown vertically on the Ag NWs network based on the hydrothermal method. This UV detector exhibited an excellent detection performance with large on/off ratio and short response time. Several process and working parameters were particularly investigated to analyze the relationship between structure and performance, which include growth time of ZnO NWs array, spin speed of Ag NWs network and working temperature. This UV photoconductive detector is based on two kinds of one-dimension nanomaterials, and it was regarded as a compromise between high performance with large area, low voltage and low cost. Project supported by the National Natural Science Foundation of China (Nos. 61176056, 91323303, 91123019), the 111 Program (No. B14040), and the Open Projects from the Institute of Photonics and Photo-Technology, Provincial Key Laboratory of Photoelectronic Technology, Northwest University, China.

  16. Solar pumped lasers and their applications

    NASA Astrophysics Data System (ADS)

    Lee, Ja H.

    Since 1980, NASA has been pursuing high power solar lasers as part of the space power beaming program. Materials in liquid, solid, and gas phases have been evaluated against the requirements for solar pumping. Two basic characteristics of solar insolation, namely its diffuse irradiance and 5800 K blackbody-like spectrum, impose rather stringent requirements for laser excitation. However, meeting these requirements is not insurmountable as solar thermal energy technology has progressed today, and taking advantage of solar pumping lasers is becoming increasingly attractive. The high density photons of concentrated solar energy have been used for mainly electric power generation and thermal processing of materials by the DOE Solar Thermal Technologies Program. However, the photons can interact with materials through many other direct kinetic paths, and applications of the concentrated photons could be extended to processes requiring photolysis, photosynthesis, and photoexcitation. The use of solar pumped lasers on Earth seems constrained by economics and sociopolitics. Therefore, prospective applications may be limited to those that require use of quantum effects and coherency of the laser in order to generate extremely high value products and services when conventional and inexpensive means are ineffective or impossible. The new applications already proposed for concentrated solar photons, such as destruction of hazardous waste, production of renewable fuel, production of fertilizer, and air/water pollution controls, may benefit from the use of inexpensive solar pumped laser matched with the photochemical kinetics of these processes.

  17. Nuclear photonics

    SciTech Connect

    Habs, D.; Guenther, M. M.; Jentschel, M.; Thirolf, P. G.

    2012-07-09

    With the planned new {gamma}-beam facilities like MEGa-ray at LLNL (USA) or ELI-NP at Bucharest (Romania) with 10{sup 13}{gamma}/s and a band width of {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -3}, a new era of {gamma} beams with energies up to 20MeV comes into operation, compared to the present world-leading HI{gamma}S facility at Duke University (USA) with 10{sup 8}{gamma}/s and {Delta}E{gamma}/E{gamma} Almost-Equal-To 3 Dot-Operator 10{sup -2}. In the long run even a seeded quantum FEL for {gamma} beams may become possible, with much higher brilliance and spectral flux. At the same time new exciting possibilities open up for focused {gamma} beams. Here we describe a new experiment at the {gamma} beam of the ILL reactor (Grenoble, France), where we observed for the first time that the index of refraction for {gamma} beams is determined by virtual pair creation. Using a combination of refractive and reflective optics, efficient monochromators for {gamma} beams are being developed. Thus, we have to optimize the total system: the {gamma}-beam facility, the {gamma}-beam optics and {gamma} detectors. We can trade {gamma} intensity for band width, going down to {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -6} and address individual nuclear levels. The term 'nuclear photonics' stresses the importance of nuclear applications. We can address with {gamma}-beams individual nuclear isotopes and not just elements like with X-ray beams. Compared to X rays, {gamma} beams can penetrate much deeper into big samples like radioactive waste barrels, motors or batteries. We can perform tomography and microscopy studies by focusing down to {mu}m resolution using Nuclear Resonance Fluorescence (NRF) for detection with eV resolution and high spatial resolution at the same time. We discuss the dominating M1 and E1 excitations like the scissors mode, two-phonon quadrupole octupole excitations, pygmy dipole excitations or giant dipole excitations under the new facet of

  18. Direct Photonic-Plasmonic Coupling and Routing in Single Nanowires

    SciTech Connect

    Yan, Rouxue; Pausauskie, Peter; Huang, Jiaxing; Yang, Piedong

    2009-10-20

    Metallic nanoscale structures are capable of supporting surface plasmon polaritons (SPPs), propagating collective electron oscillations with tight spatial confinement at the metal surface. SPPs represent one of the most promising structures to beat the diffraction limit imposed by conventional dielectric optics. Ag nano wires have drawn increasing research attention due to 2D sub-100 nm mode confinement and lower losses as compared with fabricated metal structures. However, rational and versatile integration of Ag nanowires with other active and passive optical components, as well as Ag nanowire based optical routing networks, has yet to be achieved. Here, we demonstrate that SPPs can be excited simply by contacting a silver nanowire with a SnO2 nanoribbon that serves both as an unpolarized light source and a dielectric waveguide. The efficient coupling makes it possible to measure the propagation-distance-dependent waveguide spectra and frequency-dependent propagation length on a single Ag nanowire. Furthermore, we have demonstrated prototypical photonic-plasmonic routing devices, which are essential for incorporating low-loss Ag nanowire waveguides as practical components into high-capacity photonic circuits.

  19. Fourier Transform Spectroscopy of theA2Σ+-X2ΠiTransition of AgO

    NASA Astrophysics Data System (ADS)

    O'Brien, L. C.; Wall, S. J.; Sieber, M. K.

    1997-05-01

    TheA2Σ+-X2Πinear-infrared electronic transition of AgO was observed for the first time. The spectrum was recorded with the high resolution Fourier transform spectrometer associated with the McMath-Pierce Solar Telescope at Kitt Peak. The excited AgO molecules were produced in a low pressure silver hollow cathode sputter source. Constants for theA2Σ+state of107AgO and109AgO and improvedX2Πiconstants for107AgO and109AgO are presented. These two states are not a unique perturber pair and they do not follow the pure precession model.

  20. The AGS-Booster lattice

    SciTech Connect

    Lee, Y.Y.; Barton, D.S.; Claus, J.; Cottingham, J.G.; Courant, E.D.; Danby, G.T.; Dell, G.F.; Forsyth, E.B.; Gupta, R.C.; Kats, J.

    1987-01-01

    The AGS Booster has three objectives. They are to increase the space charge limit of the AGS, to increase the intensity of the polarized proton beam by accumulating many linac pulses (since the intensity is limited by the polarized ion source), and to reaccelerate heavy ions from the BNL Tandem Van de Graaff before injection into the AGS. The machine is capable of accelerating protons at 7.5 Hertz from 200 MeV to 1.5 GeV or to lower final energies at faster repetition rates. The machine will also be able to accelerate heavy ions from as low as 1 MeV/nucleon to a magnetic rigidity as high as 17.6 Tesla-meters with a one second repetition rate. As an accumulator for polarized protons, the Booster should be able to store the protons at 200 MeV for several seconds. We expect that the Booster will increase the AGS proton intensity by a factor of four, polarized proton intensity by a factor of twenty to thirty, and will also enable the AGS to accelerate all species of heavy ions (at present the AGS heavy ion program is limited to the elements lighter than sulfur because it can only accelerate fully stripped ions). The construction project started in FY 1985 and is expected to be completed in 1989. The purpose of this paper is to provide a future reference for the AGS Booster lattice.

  1. Solar astronomy

    NASA Technical Reports Server (NTRS)

    Rosner, Robert; Noyes, Robert; Antiochos, Spiro K.; Canfield, Richard C.; Chupp, Edward L.; Deming, Drake; Doschek, George A.; Dulk, George A.; Foukal, Peter V.; Gilliland, Ronald L.

    1991-01-01

    An overview is given of modern solar physics. Topics covered include the solar interior, the solar surface, the solar atmosphere, the Large Earth-based Solar Telescope (LEST), the Orbiting Solar Laboratory, the High Energy Solar Physics mission, the Space Exploration Initiative, solar-terrestrial physics, and adaptive optics. Policy and related programmatic recommendations are given for university research and education, facilitating solar research, and integrated support for solar research.

  2. LuAG:Ce fibers for high energy calorimetry

    SciTech Connect

    Dujardin, C.; Mancini, C.; Amans, D.; Ledoux, G.; Abler, D.; Auffray, E.; Lecoq, P.; Perrodin, D.; Petrosyan, A.; Ovanesyan, K. L.

    2010-07-15

    The main objective of this contribution is to point out the potentialities of cerium doped LuAG single crystal as pixels and fibers. We first show that after optimization of growth conditions using Bridgman technology, this composition exhibits very good performances for scintillating applications (up to 26 000 photons/MeV). When grown with the micropulling down technology, fiber shapes can be obtained while the intrinsic performances are preserved. For the future high energy experiments requiring new detector concepts capable of delivering much richer informations about x- or gamma-ray energy deposition, unusual fiber shaped dense materials need to be developed. We demonstrate in this frame that cerium doped LuAG is a serious candidate for the next generation of ionizing radiation calorimeters.

  3. Quantum Computing using Photons

    NASA Astrophysics Data System (ADS)

    Elhalawany, Ahmed; Leuenberger, Michael

    2013-03-01

    In this work, we propose a theoretical model of two-quantum bit gates for quantum computation using the polarization states of two photons in a microcavity. By letting the two photons interact non-resonantly with four quantum dots inside the cavity, we obtain an effective photon-photon interaction which we exploit for the implementation of an universal XOR gate. The two-photon Hamiltonian is written in terms of the photons' total angular momentum operators and their states are written using the Schwinger representation of the total angular momentum.

  4. Spin dynamics simulations at AGS

    SciTech Connect

    Huang, H.; MacKay, W.W.; Meot, F.; Roser, T.

    2010-05-23

    To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electromagnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.

  5. NMR investigation of Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Son, Kwanghyo; Jang, Zeehoon

    2013-01-01

    109Ag nuclear magnetic resonance (NMR) and relaxation measurements have been performed on two powder samples of Ag nanoparticles with average sizes of 20 nm and 80 nm. The measurements have been done in an external field of 9.4 T and in the temperature range 10 K < T < 280 K. The 109Ag NMR spectra for both samples have close to Lorentzian shapes and turn out to be mixtures of homogeneous and inhomogeneous lines. The linewidth Δ ν at room temperature is 1.3 kHz for both samples and gradually increases with decreasing temperature. Both the Knight shift ( K) and the nuclear spin-lattice relaxation rate (1/ T 1) are observed to be almost identical to the values reported for the bulk Ag metal, whereby the Korringa ratio R(= K 2 T 1 T/S) is found to be 2.0 for both samples in the investigated temperature range.

  6. Controllable photon source

    NASA Astrophysics Data System (ADS)

    Oszetzky, Dániel; Nagy, Attila; Czitrovszky, Aladár

    2006-10-01

    We have developed our pervious experimental setup using correlated photon pairs (to the calibration of photo detectors) to realize a controllable photon source. For the generation of such photon pairs we use the non-linear process of parametric down conversion. When a photon of the pump beam is incident to a nonlinear crystal with phase matching condition, a pair of photons (signal and idler) is created at the same time with certain probability. We detect the photons in the signal beam with a single photon counting module (SPCM), while delaying those in the idler beam. Recently we have developed a fast electronic unit to control an optical shutter (a Pockels cell) placed to the optical output of the idler beam. When we detect a signal photon with the controlling electronic unit we are also able to open or close the fast optical shutter. Thus we can control which idler photons can propagate through the Pockels cell. So with this photon source we are able to program the number of photons in a certain time window. This controllable photon source that is able to generate a known number of photons with specified wavelength, direction, and polarization could be useful for applications in high-accuracy optical characterisation of photometric devices at the ultra-low intensities. This light source can also serve as a standard in testing of optical image intensifiers, night vision devices, and in the accurate measurement of spectral distribution of transmission and absorption in optical materials.

  7. Spectral investigation of nonlinear local field effects in Ag nanoparticles

    SciTech Connect

    Sato, Rodrigo Takeda, Yoshihiko; Ohnuma, Masato; Oyoshi, Keiji

    2015-03-21

    The capability of Ag nanoparticles to modulate their optical resonance condition, by optical nonlinearity, without an external feedback system was experimentally demonstrated. These optical nonlinearities were studied in the vicinity of the localized surface plasmon resonance (LSPR), using femtosecond pump-and-probe spectroscopy with a white-light continuum probe. Transient transmission changes ΔT/T exhibited strong photon energy and particle size dependence and showed a complex and non-monotonic change with increasing pump light intensity. Peak position and change of sign redshift with increasing pump light intensity demonstrate the modulation of the LSPR. These features are discussed in terms of the intrinsic feedback via local field enhancement.

  8. High energy photon-photon collisions

    SciTech Connect

    Brodsky, S.J.; Zerwas, P.M.

    1994-07-01

    The collisions of high energy photons produced at a electron-positron collider provide a comprehensive laboratory for testing QCD, electroweak interactions and extensions of the standard model. The luminosity and energy of the colliding photons produced by back-scattering laser beams is expected to be comparable to that of the primary e{sup +}e{sup {minus}} collisions. In this overview, we shall focus on tests of electroweak theory in photon-photon annihilation, particularly {gamma}{gamma} {yields} W{sup +}W{sup {minus}}, {gamma}{gamma} {yields} Higgs bosons, and higher-order loop processes, such as {gamma}{gamma} {yields} {gamma}{gamma}, Z{gamma} and ZZ. Since each photon can be resolved into a W{sup +}W{sup minus} pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. We also review high energy {gamma}{gamma} tests of quantum chromodynamics, such as the scaling of the photon structure function, t{bar t} production, mini-jet processes, and diffractive reactions.

  9. Photonic crystal and photonic wire device structures

    NASA Astrophysics Data System (ADS)

    De La Rue, Richard; Sorel, Marc; Johnson, Nigel; Rahman, Faiz; Ironside, Charles; Cronin, Lee; Watson, Ian; Martin, Robert; Jin, Chongjun; Pottier, Pierre; Chong, Harold; Gnan, Marco; Jugessur, Aju; Camargo, Edilson; Erwin, Grant; Md Zain, Ahmad; Ntakis, Iraklis; Hobbs, Lois; Zhang, Hua; Armenise, Mario; Ciminelli, Caterina; Coquillat, Dominique

    2005-09-01

    Photonic devices that exploit photonic crystal (PhC) principles in a planar environment continue to provide a fertile field of research. 2D PhC based channel waveguides can provide both strong confinement and controlled dispersion behaviour. In conjunction with, for instance, various electro-optic, thermo-optic and other effects, a range of device functionality is accessible in very compact PhC channel-guide devices that offer the potential for high-density integration. Low enough propagation losses are now being obtained with photonic crystal channel-guide structures that their use in real applications has become plausible. Photonic wires (PhWs) can also provide strong confinement and low propagation losses. Bragg-gratings imposed on photonic wires can provide dispersion and frequency selection in device structures that are intrinsically simpler than 2D PhC channel guides--and can compete with them under realistic conditions.

  10. Photonic Design for Photovoltaics

    SciTech Connect

    Kosten, E.; Callahan, D.; Horowitz, K.; Pala, R.; Atwater, H.

    2014-08-28

    We describe photonic design approaches for silicon photovoltaics including i) trapezoidal broadband light trapping structures ii) broadband light trapping with photonic crystal superlattices iii) III-V/Si nanowire arrays designed for broadband light trapping.

  11. Photonic crystal light source

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu; Bur, James A.

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  12. Strong magnetization damping induced by Ag nanostructures in Ag/NiFe/Ag trilayers

    NASA Astrophysics Data System (ADS)

    Ley Domínguez, D.; da Silva, G. L.; Rodríguez-Suárez, R. L.; Rezende, S. M.; Azevedo, A.

    2013-07-01

    Ferromagnetic resonance has been used to investigate the magnetization relaxation in trilayers of Ag(t)/NiFe(10 nm)/Ag(t), sputter deposited on Si(001) where the thickness of the Ag layer varied from 0 nm to 24 nm. In the first stages of formation, the Ag layers form islands that work as mold to imprint defects or inhomogeneities on the NiFe film surface. The magnetic inhomogeneities and defects imprinted on the surface of the NiFe film act as extrinsic sources of magnetization relaxation in addition to the intrinsic Gilbert damping mechanism. Weak inhomogeneities are associated to the two-magnon scattering source and the strong inhomogeneities are associated to the fluctuations of the local magnetization. By adding the three different sources of magnetization damping, we were able to explain the azimuthal dependence of the ferromagnetic resonance linewidth.

  13. Tailoring the Optical Properties of Silicon with Ion Beam Created Nanostructures for Advanced Photonics Applications

    NASA Astrophysics Data System (ADS)

    Akhter, Perveen

    In today's fast life, energy consumption has increased more than ever and with that the demand for a renewable and cleaner energy source as a substitute for the fossil fuels has also increased. Solar radiations are the ultimate source of energy but harvesting this energy in a cost effective way is a challenging task. Si is the dominating material for microelectronics and photovoltaics. But owing to its indirect band gap, Si is an inefficient light absorber, thus requiring a thickness of solar cells beyond tens of microns which increases the cost of solar energy. Therefore, techniques to increase light absorption in thin film Si solar cells are of great importance and have been the focus of research for a few decades now. Another big issue of technology in this fast-paced world is the computing rate or data transfer rate between components of a chip in ultra-fast processors. Existing electronic interconnects suffering from the signal delays and heat generation issues are unable to handle high data rates. A possible solution to this problem is in replacing the electronic interconnects with optical interconnects which have large data carrying capacity. However, optical components are limited in size by the fundamental laws of diffraction to about half a wavelength of light and cannot be combined with nanoscale electronic components. Tremendous research efforts have been directed in search of an advanced technology which can bridge the size gap between electronic and photonic worlds. An emerging technology of "plasmonics'' which exploits the extraordinary optical properties of metal nanostructures to tailor the light at nanoscale has been considered a potential solution to both of the above-mentioned problems. Research conducted for this dissertation has an overall goal to investigate the optical properties of silicon with metal nanostructures for photovoltaics and advanced silicon photonics applications. The first part of the research focuses on achieving enhanced

  14. Synthesis of Ag(2) S-Ag nanoprisms and their use as DNA hybridization probes.

    PubMed

    Liu, Bing; Ma, Zhanfang

    2011-06-01

    A simple synthetic route to prepare Ag(2) S-Ag nanoprisms consists of the facile addition of Na(2) S to a solution of triangular Ag nanoprisms. The resulting Ag(2) S-Ag nanoparticles are more stable in solution than the original Ag nanoprisms, and two surface plasmon resonance (SPR) bands of the original Ag nanoprisms still remain. In addition, the SPR bands of the Ag(2) S-Ag nanoprisms are tunable over a wide range. The Ag(2) S-Ag nanoprisms can be directly bioconjugated via well-established stable Ag(2) S surface chemistry with readily available sulfur coupling agents. The nanoprisms are used in the hybridization of functionalized oligonucleotides, and show promise as probes for future biosensing applications. PMID:21538868

  15. Highly active WO3-Ag-ZnO photocatalyst driven by day light illumination

    NASA Astrophysics Data System (ADS)

    Subash, B.; Krishnakumar, B.; Sreedhar, B.; Swaminathan, M.; Shanthi, M.

    2013-02-01

    The WO3 loaded Ag-ZnO (WO3-Ag-ZnO) was successfully synthesized by precipitation-decomposition method. The catalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), transmission electron microscope (TEM), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and BET surface area measurements. The photocatalytic activity of WO3-Ag-ZnO was investigated for the degradation of Naphthol Blue Black (NBB) in aqueous solution using solar light. WO3-Ag-ZnO is found to be more efficient than Ag-ZnO, WO3-ZnO, Ag-WO3, WO3, commercial ZnO, bare ZnO, TiO2-P25 and TiO2 (Merck) at pH 9 for the mineralization of NBB dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of NBB dye have been analyzed. The mineralization of NBB has been confirmed by Chemical Oxygen Demand (COD) measurements. A degradation mechanism is proposed for the degradation of NBB under solar light. This catalyst is found to be reusable.

  16. Study of the oxygen transport through Ag (110), Ag (poly), and Ag 2.0 Zr

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Wu, D.; Davidson, M. R.; Hoflund, Gar B.

    1992-01-01

    The transport of oxygen through high-purity membranes of Ag (110), Ag (poly), Ag (nano), and Ag 2.0 Zr has been studied by an ultrahigh vacuum permeation method over the temperature range of 400-800 C. The data show that there are substantial deviations from ordinary diffusion-controlled transport. A surface limitation has been confirmed by glow-discharge studies where the upstream O2 supply has been partially converted to atoms, which, for the same temperature and pressure, gave rise to over an order of magnitude increase in transport flux. Further, the addition of 2.0 wt percent Zr to the Ag has provided increased dissociative adsorption rates, which, in turn, increased the transport flux by a factor of 2. It was also observed that below a temperature of 630 C, the diffusivity exhibits an increase in activation energy of over 4 kcal/mol, which has been attributed to trapping of the atomic oxygen and/or kinetic barriers at the surface and subsurface of the vacuum interface. Above 630 C, the activation barrier decreases to the accepted value of about 11 kcal/mol for Ag (poly), consistent with zero concentration at the vacuum interface.

  17. Enhancing light trapping properties of thin film solar cells by plasmonic effect of silver nanoparticles.

    PubMed

    Jung, Junhee; Ha, Kyungyeon; Cho, Jaehyun; Ahn, Shihyun; Park, Hyeongsik; Hussain, Shahzada Qamar; Choi, Mansoo; Yi, Junsin

    2013-12-01

    The preparation of thin film silicon solar cells containing Ag nanoparticles is reported in this article. Ag nanoparticles were deposited on fluorine doped tin oxide coated glass substrates by the evaporation and condensation method. a-Si:H solar cells were deposited on these substrates by cluster type plasma enhanced chemical vapor deposition. We discuss the double textured surface effect with respect to both the surface morphology of the substrate and the plasmonic effect of the Ag nanoparticles. Ag nanoparticles of various sizes from 10 to 100 nm were deposited. The haze values of the Ag embedded samples increased with increasing particle size whereas the optical transmittance decreased at the same conditions. The solar cell with the 30 nm size Ag nanoparticles showed a short circuit current density of 12.97 mA/cm2, which is 0.53 mA/cm2 higher than that of the reference solar cell without Ag nanoparticles, and the highest quantum efficiency for wavelengths from 550 to 800 nm. When 30 nm size nanoparticles were employed, the conversion efficiency of the solar cell was increased from 6.195% to 6.696%. This study reports the application of the scattering effect of Ag nanoparticles for the improvement of the conversion efficiency of amorphous silicon solar cells. PMID:24266153

  18. Resource recovery of scrap silicon solar battery cell.

    PubMed

    Lee, Ching-Hwa; Hung, Chi-En; Tsai, Shang-Lin; Popuri, Srinivasa R; Liao, Ching-Hua

    2013-05-01

    In order to minimize pollution problems and to conserve limited natural resources, a hydrometallurgical procedure was developed in this study to recover the valuable resources of silicon (Si), silver (Ag) and aluminum (Al) from scrap silicon solar battery cells. In this study, several methods of leaching, crystallization, precipitation, electrolysis and replacement were employed to investigate the recovery efficiency of Ag and Al from defective monocrystalline silicon solar battery cells. The defective solar battery cells were ground into powder followed by composition analysis with inductively coupled plasma-atomic emission spectrometry. The target metals Ag and Al weight percentage were found to be 1.67 and 7.68 respectively. A leaching process was adopted with nitric acid (HNO3), hydrochloric acid, sulfuric acid (H2SO4) and sodium hydroxide as leaching reagent to recover Ag and Al from a ground solar battery cell. Aluminum was leached 100% with 18N H2SO4 at 70°C and Ag was leached 100% with 6N HNO3. Pure Si of 100% was achieved from the leaching solution after the recovery of Ag and Al, and was analyzed by scanning electron microscope-energy dispersive spectroscopy. Aluminum was recovered by crystallization process and silver was recovered by precipitation, electrolysis and replacement processes. These processes were applied successfully in the recovery of valuable metal Ag of 98-100%. PMID:23460539

  19. Upconversion in solar cells

    PubMed Central

    2013-01-01

    The possibility to tune chemical and physical properties in nanosized materials has a strong impact on a variety of technologies, including photovoltaics. One of the prominent research areas of nanomaterials for photovoltaics involves spectral conversion. Modification of the spectrum requires down- and/or upconversion or downshifting of the spectrum, meaning that the energy of photons is modified to either lower (down) or higher (up) energy. Nanostructures such as quantum dots, luminescent dye molecules, and lanthanide-doped glasses are capable of absorbing photons at a certain wavelength and emitting photons at a different (shorter or longer) wavelength. We will discuss upconversion by lanthanide compounds in various host materials and will further demonstrate upconversion to work for thin-film silicon solar cells. PMID:23413889

  20. Study of the time response of a LuAG(Pr) crystal for fast timing applications

    NASA Astrophysics Data System (ADS)

    Fraile, L. M.; Mach, H.; Picado, E.; Vedia, V.; Udías, J. M.

    2013-06-01

    The recently developed praseodymium-doped lutetium aluminum garnet, LuAG(Pr), holds a strong potential for fast timing applications. In this study we report on the time response of LuAG(Pr) at 22Na and 60Co photon energies. The measurements were performed using a small crystal cube of 1 cm3 coupled to a Hamamatsu R5320 photomultiplier tube. The full width at half maximum (FWHM) time resolution is found to be 147±2 ps at 60Co energies, and 238±2 ps at 22Na.

  1. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-01

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution

  2. Simultaneous Two-Photon Absorption to Gerade Excited Singlet States of Diphenylacetylene and Diphenylbutadiyne Using Optical-Probing Photoacoustic Spectroscopy.

    PubMed

    Isozaki, Tasuku; Oba, Hikari; Ikoma, Tadaaki; Suzuki, Tadashi

    2016-08-11

    Simultaneous two-photon absorption to one-photon forbidden electronically excited states of diphenylacetylene (DPA) and diphenylbutadiyne (DPB) was investigated by means of highly sensitive optical-probing photoacoustic spectroscopy. The incident laser power dependencies on photoacoustic signal intensity indicate that the signals are dominated by the two-photon absorption regime. Two-photon absorption is responsible for transitions to gerade excited states based on the selection rule. The two-photon absorption bands observed in the heat action spectra were assigned with the aid of quantum chemical calculations. The relative magnitude of the two-photon absorption cross sections of DPA and DPB was estimated, and the larger two-photon absorption cross section of DPB was related to the resonance effect with the red-shifted one-photon allowed 1(1)B1u ← 1(1)Ag transition of DPB. PMID:27410388

  3. Efficient enhancement of hydrogen production by Ag/Cu2O/ZnO tandem triple-junction photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Ren, Feng; Shen, Shaohua; Fu, Yanming; Chen, Chao; Liu, Chang; Xing, Zhuo; Liu, Dan; Xiao, Xiangheng; Wu, Wei; Zheng, Xudong; Liu, Yichao; Jiang, Changzhong

    2015-03-01

    Highly efficient semiconductor photoelectrodes for solar hydrogen production through photocatalytic water splitting are a promising and challenge solution to solve the energy problems. In this work, Ag/Cu2O/ZnO tandem triple-junction photoelectrode was designed and prepared. An increase of 11 times of photocurrent is achieved in the Ag/Cu2O/ZnO photoelectrode comparing to that of the Cu2O film. The high performance of the Ag/Cu2O/ZnO film is due to the optimized design of the tandem triple-junction structure, where the localized surface Plasmon resonance of Ag and the hetero-junctions efficiently absorb solar energy, produce, and separate electron-hole pairs in the photocathode.

  4. Optical, electrical, and structural properties of ZrON/Ag/ZrON multilayer transparent conductor for organic photovoltaics application

    NASA Astrophysics Data System (ADS)

    Song, Jun-Hyuk; Jeon, Joon-Woo; Kim, Yong-Hyun; Oh, Joon-Ho; Seong, Tae-Yeon

    2013-10-01

    We investigated the electrical and optical properties of chemically stable nitride-based ZrON/Ag/ZrON multilayers for use in organic photovoltaics. As the ZrON layer thickness increases, the carrier concentration smoothly decreases and the transmission window region becomes wider and gradually shifts toward the lower energy-side. The optical bandgap also decreases with decreasing carrier concentration. The ZrON/Ag/ZrON samples exhibit somewhat lower transmittance in the region of ˜400-800 nm than the ITO/Ag/ITO samples. The aging test shows that the resistivity of the ZrON/Ag/ZrON samples remains almost the same even after aging for 1 month in air. It is shown that the ZrON/Ag interface is more chemically stable than the ITO/Ag interface. Simulation results exhibit that the ZnPc:C60 bulk hetero-junction organic solar cells fabricated with the ZrON(30 nm)/Ag/ZrON(70 nm) layers give a short circuit current of 9.54 mA/cm2, which is comparable to that (10.54 mA/cm2) of the cells with 90-nm-thick ITO electrodes. The ZrON/Ag/ZrON samples experienced a large shift in the absorption edge. This behavior is explained in terms of the material characteristics of the ZrON layers and the higher refractive index of the ZrON/Ag/ZrON samples.

  5. Design of plasmonic backcontact nanogratings for broadband and polarization-insensitive absorption enhancement in thin-film solar cell

    NASA Astrophysics Data System (ADS)

    Firoozi, Arezoo; Mohammadi, Ahmad

    2015-05-01

    We discuss the rules for designing nanostructured plasmonic backcontact of thin-film crystalline silicon solar cells using two-dimensional finite-difference time-domain (2D-FDTD) method. A novel efficient quasi-periodic plasmonic nanograting is designed. Numerical calculations demonstrate that broadband and polarization-insensitive absorption enhancement is achieved by the proposed structure which is based on a supercell geometry containing N subcells in each of which there is one Ag nanowire deposited on the backcontact of the solar cell. The proposed structure offers the possibility of controlling the number and location of photonic and plasmonic modes and outperforms the periodic plasmonic nanogratings which only utilize plasmonic resonances. We start by tuning the plasmonic mode of one subcell and then construct the supercell based on the final design of the subcell. Our findings show that with a proper choice of key parameters of the nanograting, several photonic and plasmonic modes can be excited across the entire spectral region where crystalline silicon (c-Si) is absorbing. The absorption enhancement is significant, particularly in the long wavelength region where c-Si is weakly absorbing.

  6. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures

    NASA Astrophysics Data System (ADS)

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-11-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au+ ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

  7. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

    PubMed

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-12-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures. PMID:26563266

  8. Robust Ag nanoplate ink for flexible electronics packaging

    SciTech Connect

    Li, Ruo -Zhou; Hu, Anming; Bridges, Denzel; Oakes, Ken D.; Peng, Rui; Tumuluri, Uma; Wu, Zili; Feng, Zhili; Zhang, Tong

    2015-03-24

    Nanoinks are currently a topic of heightened interest with respect to low temperature bonding processes and printable electronics. We have developed an innovative polyvinylpyrrolidone (PVP)-stabilized Ag nanoplate ink amenable to very strong low temperature packaging, and investigated the relationship between bonding strength and electrical conductivity post-bonding. PVP shell plastic deformations observed in failure microcracks with the formation of PVP nanofibers, revealed bonding strength at low temperatures (<250 °C) was primarily due to adhesive bonding. It is found that, utilizing photonic sintering, ~70 °C reduction of transformation temperature from adhesive to metallic bonding was achieved compared to that of thermal sintering. A numerical simulation was developed to better understand the influences of the light-induced heat generation, which demonstrated near-infrared light can facilitate sintering. Bonding strengths of 27 MPa were achieved at room temperatures, and 29.4 MPa at 210 °C with photonic sintering. Moreover, the anisotropic resistivity was observed with different thermal dependences. Furthermore, these results demonstrate Ag nanoplate inks have potential for low temperature 3D interconnections in lead-free microcircuits, flexible electronic packaging, and diverse sensing applications.

  9. Robust Ag nanoplate ink for flexible electronics packaging

    DOE PAGESBeta

    Li, Ruo -Zhou; Hu, Anming; Bridges, Denzel; Oakes, Ken D.; Peng, Rui; Tumuluri, Uma; Wu, Zili; Feng, Zhili; Zhang, Tong

    2015-03-24

    Nanoinks are currently a topic of heightened interest with respect to low temperature bonding processes and printable electronics. We have developed an innovative polyvinylpyrrolidone (PVP)-stabilized Ag nanoplate ink amenable to very strong low temperature packaging, and investigated the relationship between bonding strength and electrical conductivity post-bonding. PVP shell plastic deformations observed in failure microcracks with the formation of PVP nanofibers, revealed bonding strength at low temperatures (<250 °C) was primarily due to adhesive bonding. It is found that, utilizing photonic sintering, ~70 °C reduction of transformation temperature from adhesive to metallic bonding was achieved compared to that of thermal sintering.more » A numerical simulation was developed to better understand the influences of the light-induced heat generation, which demonstrated near-infrared light can facilitate sintering. Bonding strengths of 27 MPa were achieved at room temperatures, and 29.4 MPa at 210 °C with photonic sintering. Moreover, the anisotropic resistivity was observed with different thermal dependences. Furthermore, these results demonstrate Ag nanoplate inks have potential for low temperature 3D interconnections in lead-free microcircuits, flexible electronic packaging, and diverse sensing applications.« less

  10. Robust Ag nanoplate ink for flexible electronics packaging.

    PubMed

    Li, Ruo-Zhou; Hu, Anming; Bridges, Denzel; Zhang, Tong; Oakes, Ken D; Peng, Rui; Tumuluri, Uma; Wu, Zili; Feng, Zhili

    2015-04-28

    Nanoinks are currently a topic of heightened interest with respect to low temperature bonding processes and printable electronics. We have developed an innovative polyvinylpyrrolidone (PVP)-stabilized Ag nanoplate ink amenable to very strong low temperature packaging, and investigated the relationship between bonding strength and electrical conductivity post-bonding. PVP shell plastic deformations observed in failure microcracks with the formation of PVP nanofibers, revealed bonding strength at low temperatures (<250 °C) was primarily due to adhesive bonding. It is found that, utilizing photonic sintering, ∼ 70 °C reduction of transformation temperature from adhesive to metallic bonding was achieved compared to that of thermal sintering. A numerical simulation was developed to better understand the influences of the light-induced heat generation, which demonstrated near-infrared light can facilitate sintering. Bonding strengths of 27 MPa were achieved at room temperatures, and 29.4 MPa at 210 °C with photonic sintering. Moreover, the anisotropic resistivity was observed with different thermal dependences. These results demonstrate Ag nanoplate inks have potential for low temperature 3D interconnections in lead-free microcircuits, flexible electronic packaging, and diverse sensing applications. PMID:25824693

  11. Probing the rupture of a Ag atomic junction in a Ag-Au mixed electrode

    NASA Astrophysics Data System (ADS)

    Kim, Taekyeong

    2015-09-01

    We probed that the atomic junction in Ag part ruptures during stretching of atomic sized contacts of Ag-Au mixed electrodes, resulting in Ag-Ag electrodes through a scanning tunneling microscope breaking junction (STM-BJ) technique. We observed that the conductance and tunneling decay constant for a series of amine-terminated oligophenyl molecular junctions are essentially the same for the Ag-Au mixed and the Ag-Ag electrodes. We also found the molecular plateau length and the evolution patterns with the Ag-Au mixed electrodes are similar to those with Ag-Ag electrodes rather than the Au-Au electrodes in the molecular junction elongation. This result is attributed to the smaller binding energy of Ag atoms compared to that of Au atoms, so the Ag junction part is more easily broken than that of Au part in stretching of Ag-Au mixed electrodes. Furthermore, we successfully observed that the rupture force of the atomic junction for the Ag-Au mixed electrodes was identical to that for the Ag-Ag electrodes and smaller than that for the Au-Au electrodes. This study may advance the understanding of the electrical and the mechanical properties in molecular devices with Ag and Au electrodes in future.

  12. Light harvesting in photonic crystals revisited: why do slow photons at the blue edge enhance absorption?

    PubMed

    Deparis, O; Mouchet, S R; Su, B-L

    2015-11-11

    Light harvesting enhancement by slow photons in photonic crystal catalysts or dye-sensitized solar cells is a promising approach for increasing the efficiency of photoreactions. This structural effect is exploited in inverse opal TiO2 photocatalysts by tuning the red edge of the photonic band gap to the TiO2 electronic excitation band edge. In spite of many experimental demonstrations, the slow photon effect is not fully understood yet. In particular, observed enhancement by tuning the blue edge has remained unexplained. Based on rigorous couple wave analysis simulations, we quantify light harvesting enhancement in terms of absorption increase at a specific wavelength (monochromatic UV illumination) or photocurrent increase (solar light illumination), with respect to homogeneous flat slab of equivalent material thickness. We show that the commonly accepted explanation relying on light intensity confinement in high (low) dielectric constant regions at the red (blue) edge is challenged in the case of TiO2 inverse opals because of the sub-wavelength size of the material skeleton. The reason why slow photons at the blue edge are also able to enhance light harvesting is the loose confinement of the field, which leads to significant resonantly enhanced field intensity overlap with the skeleton in both red and blue edge tuning cases, yet with different intensity patterns. PMID:26517229

  13. Plasmonic effects of au/ag bimetallic multispiked nanoparticles for photovoltaic applications.

    PubMed

    Sharma, Manisha; Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Vinogradova, Ekaterina; Ayon, Arturo A

    2014-09-10

    In recent years, there has been considerable interest in the use of plasmons, that is, free electron oscillations in conductors, to boost the performance of both organic and inorganic thin film solar cells. This has been driven by the possibility of employing thin active layers in solar cells in order to reduce materials costs, and is enabled by significant advances in fabrication technology. The ability of surface plasmons in metallic nanostructures to guide and confine light in the nanometer scale has opened up new design possibilities for solar cell devices. Here, we report the synthesis and characterization of highly monodisperse, reasonably stable, multipode Au/Ag bimetallic nanostructures using an inorganic additive as a ligand for photovoltaic applications. A promising surface enhanced Raman scattering (SERS) effect has been observed for the synthesized bimetallic Au/Ag multispiked nanoparticles, which compare favorably well with their Au and Ag spherical nanoparticle counterparts. The synthesized plasmonic nanostructures were incorporated on the rear surface of an ultrathin planar c-silicon/organic polymer hybrid solar cell, and the overall effect on photovoltaic performance was investigated. A promising enhancement in solar cell performance parameters, including both the open circuit voltage (VOC) and short circuit current density (JSC), has been observed by employing the aforementioned bimetallic multispiked nanoparticles on the rear surface of solar cell devices. A power conversion efficiency (PCE) value as high as 7.70% has been measured in a hybrid device with Au/Ag multispiked nanoparticles on the rear surface of an ultrathin, crystalline silicon (c-Si) membrane (∼ 12 μm). This value compares well to the measured PCE value of 6.72% for a similar device without nanoparticles. The experimental observations support the hope for a sizable PCE increase, due to plasmon effects, in thin-film, c-Si solar cells in the near future. PMID:25137194

  14. Infrared spectrum of the Ag(+)-(pyridine)2 ionic complex: probing interactions in artificial metal-mediated base pairing.

    PubMed

    Chakraborty, Shamik; Dopfer, Otto

    2011-07-11

    The isolated pyridine-Ag(+)-pyridine unit (Py-Ag(+)-Py) is employed as a model system to characterize the recently observed Ag(+)-mediated base pairing in DNA oligonucleotides at the molecular level. The structure and infrared (IR) spectrum of the Ag(+)-Py(2) cationic complex are investigated in the gas phase by IR multiple-photon dissociation (IRMPD) spectroscopy and quantum chemical calculations to determine the preferred metal-ion binding site and other salient properties of the potential-energy surface. The IRMPD spectrum has been obtained in the 840-1720 cm(-1) fingerprint region by coupling the IR free electron laser at the Centre Laser Infrarouge d'Orsay (CLIO) with a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with an electrospray ionization source. The spectroscopic results are interpreted with quantum chemical calculations conducted at the B3LYP/aug-cc-pVDZ level. The analysis of the IRMPD spectrum is consistent with a σ complex, in which the Ag(+) ion binds to the nitrogen lone pairs of the two Py ligands in a linear configuration. The binding motif of Py-Ag(+)-Py in the gas phase is the same as that observed in Ag(+)-mediated base pairing in solution. Ag(+) bonding to the π-electron system of the aromatic ring is predicted to be a substantially less-favorable binding motif. PMID:21442717

  15. Enhanced photochemistry of ethyl chloride on Ag nanoparticles.

    PubMed

    Toker, Gil; Bespaly, Alexander; Zilberberg, Liat; Asscher, Micha

    2015-02-11

    Enhanced photodecomposition of ethyl chloride (EC) adsorbed on SiO2/Si (100) supported silver nanoparticles (Ag NPs) under ultrahigh vacuum (UHV) conditions has been studied in order to assess the potential contribution of plasmonic effects. The cross section for photodecomposition of EC and overall photoyield were found to increase with increasing photon energy regardless of the plasmon resonant wavelength and with Ag coverage without any noticeable particle size effect. The influence of EC-Ag NPs separation distance on the rate of EC decomposition was studied in order to examine potential local electric field influence on the photodissociation process. Long (∼5 nm) photoactivity decay distance has been observed which excludes local surface plasmon dominance in the photodecomposition event. These findings suggest that the alignment of excited electron energy and adsorbate affinity levels is central for efficient photochemical reactions, whereas short-range electric field enhancement by plasmon excitation on top and at the immediate vicinity of silver nanoparticles does not have any measurable effect. PMID:25555201

  16. The AGS Booster control system

    SciTech Connect

    Frankel, R.; Auerbach, E.; Culwick, B.; Clifford, T.; Mandell, S.; Mariotti, R.; Salwen, C.; Schumburg, N.

    1988-01-01

    Although moderate in size, the Booster construction project requires a comprehensive control system. There are three operational modes: as a high intensity proton injector for the AGS, as a heavy ion accelerator and injector supporting a wide range of ions and as a polarized proton storage injector. These requirements are met using a workstation based extension of the existing AGS control system. Since the Booster is joining a complex of existing accelerators, the new system will be capable of supporting multiuser operational scenarios. A short discussion of this system is discussed in this paper.

  17. Core-size-dependent catalytic properties of bimetallic Au/Ag core-shell nanoparticles.

    PubMed

    Haldar, Krishna Kanta; Kundu, Simanta; Patra, Amitava

    2014-12-24

    Bimetallic core-shell nanoparticles have recently emerged as a new class of functional materials because of their potential applications in catalysis, surface enhanced Raman scattering (SERS) substrate and photonics etc. Here, we have synthesized Au/Ag bimetallic core-shell nanoparticles with varying the core diameter. The red-shifting of the both plasmonic peaks of Ag and Au confirms the core-shell structure of the nanoparticles. Transmission electron microscopy (TEM) analysis, line scan EDS measurement and UV-vis study confirm the formation of core-shell nanoparticles. We have examined the catalytic activity of these core-shell nanostructures in the reaction between 4-nitrophenol (4-NP) and NaBH4 to form 4-aminophenol (4-AP) and the efficiency of the catalytic reaction is found to be increased with increasing the core size of Au/Ag core-shell nanocrystals. The catalytic efficiency varies from 41.8 to 96.5% with varying core size from 10 to 100 nm of Au/Ag core-shell nanoparticles, and the Au100/Ag bimetallic core-shell nanoparticle is found to be 12-fold more active than that of the pure Au nanoparticles with 100 nm diameter. Thus, the catalytic properties of the metal nanoparticles are significantly enhanced because of the Au/Ag core-shell structure, and the rate is dependent on the size of the core of the nanoparticles. PMID:25456348

  18. Photoreduction of Ag+ in Ag/Ag2S/Au memristor

    NASA Astrophysics Data System (ADS)

    Mou, N. I.; Tabib-Azar, M.

    2015-06-01

    Silver halides and chalcogenides are excellent memristor materials that have been extensively used in the past as photosensitive layers in photography. Here we examine the effect of illumination on the operating voltages and switching speed of Ag/Ag2S/Au memristors using a green laser (473-523 nm). Our results indicate that illumination decreases the average switching time from high to low resistance states by ∼19% and decreases the turn-off voltages dramatically from -0.8 V to -0.25 V that we attribute to the change in sulfur valency and a photo-induced change in its oxidation/reduction potential. Photo-induced reduction of silver in Ag2S may be used in three dimensional optical memories that can be electronically read and reset.

  19. Ag nanotubes and Ag/AgCl electrodes in nanoporous membranes

    NASA Astrophysics Data System (ADS)

    Davenport, Matthew; Healy, Ken; Siwy, Zuzanna S.

    2011-04-01

    Miniaturization of the entire experimental setup is a key requirement for widespread application of nanodevices. For nanopore biosensing, integrating electrodes onto the nanopore membrane and controlling the pore length is important for reducing the complexity and improving the sensitivity of the system. Here we present a method to achieve these goals, which relies on electroless plating to produce Ag nanotubes in track-etched polymer nanopore templates. By plating from one side only, we create a conductive nanotube that does not span the full length of the pore, and thus can act as a nanoelectrode located inside the nanopore. To give optimal electrochemical behavior for sensing, we coat the Ag nanotube with a layer of AgCl. We characterize the behavior of this nanoelectrode by measuring its current-voltage response and find that, in most cases, the response is asymmetric. The plated nanopores have initial diameters between 100 and 300 nm, thus a range suitable for detection of viruses.

  20. Function photonic crystals

    NASA Astrophysics Data System (ADS)

    Wu, Xiang-Yao; Zhang, Bai-Jun; Yang, Jing-Hai; Liu, Xiao-Jing; Ba, Nuo; Wu, Yi-Heng; Wang, Qing-Cai

    2011-07-01

    In this paper, we present a new kind of function photonic crystals (PCs), whose refractive index is a function of space position. Conventional PCs structure grows from two materials, A and B, with different dielectric constants εA and εB. Based on Fermat principle, we give the motion equations of light in one-dimensional, two-dimensional and three-dimensional function photonic crystals. For one-dimensional function photonic crystals, we give the dispersion relation, band gap structure and transmissivity, and compare them with conventional photonic crystals, and we find the following: (1) For the vertical and non-vertical incidence light of function photonic crystals, there are band gap structures, and for only the vertical incidence light, the conventional PCs have band gap structures. (2) By choosing various refractive index distribution functions n( z), we can obtain more wider or more narrower band gap structure than conventional photonic crystals.

  1. Ag-Ag2S Hybrid Nanoprisms: Structural versus Plasmonic Evolution.

    PubMed

    Shahjamali, Mohammad M; Zhou, Yong; Zaraee, Negin; Xue, Can; Wu, Jinsong; Large, Nicolas; McGuirk, C Michael; Boey, Freddy; Dravid, Vinayak; Cui, Zhifeng; Schatz, George C; Mirkin, Chad A

    2016-05-24

    Recently, Ag-Ag2S hybrid nanostructures have attracted a great deal of attention due to their enhanced chemical and thermal stability, in addition to their morphology- and composition-dependent tunable local surface plasmon resonances. Although Ag-Ag2S nanostructures can be synthesized via sulfidation of as-prepared anisotropic Ag nanoparticles, this process is poorly understood, often leading to materials with anomalous compositions, sizes, and shapes and, consequently, optical properties. In this work, we use theory and experiment to investigate the structural and plasmonic evolution of Ag-Ag2S nanoprisms during the sulfidation of Ag precursors. The previously observed red-shifted extinction of the Ag-Ag2S hybrid nanoprism as sulfidation occurs contradicts theoretical predictions, indicating that the reaction does not just occur at the prism tips as previously speculated. Our experiments show that sulfidation can induce either blue or red shifts in the extinction of the dipole plasmon mode, depending on reaction conditions. By elucidating the correlation with the final structure and morphology of the synthesized Ag-Ag2S nanoprisms, we find that, depending on the reaction conditions, sulfidation occurs on the prism tips and/or the (111) surfaces, leading to a core(Ag)-anisotropic shell(Ag2S) prism nanostructure. Additionally, we demonstrate that the direction of the shift in the dipole plasmon is a function of the relative amounts of Ag2S at the prism tips and Ag2S shell thickness around the prism. PMID:27148792

  2. Diagnosis of multilayer clouds using photon path length distributions

    NASA Astrophysics Data System (ADS)

    Li, Siwei; Min, Qilong

    2010-10-01

    Photon path length distribution is sensitive to 3-D cloud structures. A detection method for multilayer clouds has been developed, by utilizing the information of photon path length distribution. The photon path length method estimates photon path length information from the low level, single-layer cloud structure that can be accurately observed by a millimeter-wave cloud radar (MMCR) combined with a micropulse lidar (MPL). As multiple scattering within the cloud layers and between layers would substantially enhance the photon path length, the multilayer clouds can be diagnosed by evaluating the estimated photon path information against observed photon path length information from a co-located rotating shadowband spectrometer (RSS). The measurements of MMCR-MPL and RSS at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site have been processed for the year 2000. Cases studies illustrate the consistency between MMCR-MPL detection and the photon path length method under most conditions. However, the photon path length method detected some multilayer clouds that were classified by the MMCR-MPL as single-layer clouds. From 1 year statistics at the ARM SGP site, about 27.7% of single-layer clouds detected by the MMCR-MPL with solar zenith angle less than 70° and optical depth greater than 10 could be multilayer clouds. It suggests that a substantial portion of single-layer clouds detected by the MMCR-MPL could also be influenced by some "missed" clouds or by the 3-D effects of clouds.

  3. Photonically Engineered Incandescent Emitter

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2005-03-22

    A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

  4. Photonically engineered incandescent emitter

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2003-08-26

    A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

  5. Solar thermophotovoltaics - An assessment

    NASA Astrophysics Data System (ADS)

    Spirkl, W.; Ries, H.

    1985-05-01

    A general model of a solar thermophotovoltaic device is discussed both for improving the efficiency of one-band-gap photovoltaic cells by matching the photon energy to the band gap and for concentrating diffuse radiation. Ideal components are assumed in order to calculate theoretical maximum efficiency. It corresponds to that of a perfect selective absorber in conjunction with a Carnot-engine, ranging from 53 percent for 1 sun to 85 percent for the highest possible irradiance of 50,000 suns. The improvement over an ideal one-gap device is roughly a factor of 2. Consideration of available materials shows that any improvement in efficiency can be expected only for high irradiance of 1000 suns. The sensitive parameter is the selectivity of the absorber-emitter. Concentration of diffuse solar radiation is not feasible. Perspectives appear not much better than for existing technologies such as photovoltaics or solar tower applications.

  6. AGS experiments: 1990, 1991, 1992. Ninth edition

    SciTech Connect

    Depken, J.C.

    1993-04-01

    This report contains a description of the following: AGS Experimental Area - High Energy Physics FY 1993 and Heavy Ion Physics FY 1993; Table of Beam Parameters and Fluxes; Experiment Schedule ``as run``; Proposed 1993 Schedule; A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Publications of AGS Experiments; and List of AGS Experimenters.

  7. What Is Ag-Ed?

    ERIC Educational Resources Information Center

    Linley, Judy; Mylne, Lee

    1998-01-01

    Ag-Ed, an agricultural education project for upper elementary students, was held in conjunction with the Toowoomba Show in Queensland, Australia. Agriculture industry representatives provided 20 interactive agricultural presentations for class groups, which were supplemented with a teacher resource-package containing a directory and 13 sections of…

  8. AGS experiments, 1988, 1989, 1990

    SciTech Connect

    Depken, J.C.

    1991-04-01

    This report contains: experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; experiment long range schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS experiments; and list of experimenters.

  9. AGS experiments: 1985, 1986, 1987

    SciTech Connect

    Depken, J.C.

    1987-01-01

    This report contains: Experimental areas layout, table of beam parameters and fluxes, experiment schedule ''as run,'' experiment long range schedule, a listing of experiments by number, two-page summaries of each experiment, also ordered by number, and publications of AGS experiments, 1982-1987.

  10. AGS 20th anniversary celebration

    SciTech Connect

    Baggett, N.V.

    1980-05-22

    On May 22, 1980, a symposium was held at Brookhaven to celebrate the 20th birthday of the AGS, to recall its beginnings, and to review major discoveries that have been made with its beams. The talks at the symposium are recorded in this volume.

  11. Photonic Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Merritt, Scott; Krainak, Michael

    2016-01-01

    Integrated photonics generally is the integration of multiple lithographically defined photonic and electronic components and devices (e.g. lasers, detectors, waveguides passive structures, modulators, electronic control and optical interconnects) on a single platform with nanometer-scale feature sizes. The development of photonic integrated circuits permits size, weight, power and cost reductions for spacecraft microprocessors, optical communication, processor buses, advanced data processing, and integrated optic science instrument optical systems, subsystems and components. This is particularly critical for small spacecraft platforms. We will give an overview of some NASA applications for integrated photonics.

  12. Improvements in UV stability for FEP/Ag based thermal control materials

    NASA Astrophysics Data System (ADS)

    Grieser, James; Maas, Gerald

    2003-09-01

    Darkening of FEP/Ag based Thermal Control (TC) materials after UV exposure has been documented for several years. This End of Life (EOL) Solar Absorptance (α) increase and the corresponding performance degradation must be taken into account in the preliminary design of spacecraft. Astral Technology Unlimited, Inc. (ATU) has developed new processes and coatings to improve the UV stability of FEP/Ag based TC materials. Test results of this development effort are presented. Data for several new coating combinations along with data on the current "Industry Standard" material are compared for up to 27,000 Equivalent Sun Hours (ESH) of UV exposure. The resulting solar absorptance improvements are very dramatic and should allow future satellite designs with the EOL solar alpha to be nearly identical to the Beginning of Life (BOL) values. Satellites using these new TC materials can have optimum thermal-optical performance for the life of the spacecraft.

  13. Direct-Write Contacts for Solar Cells

    SciTech Connect

    Kaydanova, T.; van Hest, M.F.A.M.; Miedaner, A.; Curtis, C. J.; Alleman, J. L.; Dabney, M. S.; Garnett, E.; Shaheen, S.; Ginley, D. S.; Smith, L.; Collins, R.; Hanoka, J. I.; Gabor, A. M.

    2005-01-01

    We report on our project to develop inkjet printable contacts for solar cells. Ag, Cu, and Ni metallizations were inkjet printed with near vacuum deposition quality. Thick, highly conducting lines of Ag and Cu demonstrating good adhesion to glass, Si, and PCB have been printed at 100-200 C in air and N2, respectively. Ag grids were inkjet-printed on Si solar cells and fired through silicon nitride AR layer at 850 C resulting in 8% cells. Next-generation multicomponent inks (including etching agents) have also been developed with improved fire-through contacts leading to higher cell efficiencies. The approach developed can be easily extended to other conductors such as Pt, Pd, and Au, etc. In addition, PEDOT-PSS polymer-based conductors were inkjet-printed with the conductivity as good or better than those of polymer-based conductors.

  14. Optical power limiting in ensembles of colloidal Ag2S quantum dots

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, O. V.; Smirnov, M. S.; Perepelitsa, A. S.; Shatskikh, T. S.; Shapiro, B. I.

    2015-12-01

    The effect of power limiting for optical radiation at a wavelength of 660 nm with a pulse duration of 10 ms and operation threshold of 2.2 - 3.1 mJ cm-2 is observed in ensembles of colloidal Ag2S quantum dots (QDs). Using the z-scanning method in an open-aperture scheme it is found that the power is limited mainly due to reverse saturable absorption caused by two-photon optical transitions that involve energy levels of Ag2S photoluminescence centres, related to structural impurity defects in colloidal Ag2S QDs. At the same time, the z-scanning in a closed-aperture scheme demonstrates the formation of a thermal dynamic lens.

  15. An efficient photocatalyst for degradation of various organic dyes: Ag@Ag2MoO4-AgBr composite.

    PubMed

    Bai, Yu-Yang; Lu, Yi; Liu, Jin-Ku

    2016-04-15

    The Ag2MoO4-AgBr composite was prepared by a facile in-situ anion-exchange method, then the Ag nanoparticles were coated on this composite through photodeposition route to form a novel Ag@Ag2MoO4-AgBr composite. The in-situ Br(-) replacement in a crystal lattice node position of Ag2MoO4 crystal allows for overcoming the resistance of electron transition effectively. Meanwhile silver nano-particles on the surface of Ag@Ag2MoO4-AgBr composite could act as electron traps to intensify the photogeneration electron-hole separation and the subsequent transfer of the trapped electron to the adsorbed O2 as an electron acceptor. As an efficient visible light catalyst, the Ag@Ag2MoO4-AgBr composite exhibited superior photocatalytic activity for the degradation of various organic dyes. The experimental results demonstrated superior photocatalytic rate of Ag@Ag2MoO4-AgBr composite compared to pure AgBr and Ag2MoO4 crystals (37.6% and 348.4% enhancement respectively). The Ag@Ag2MoO4-AgBr composite cloud degraded Rhodamin B, bromophenol blue, and amino black 10b completed in 7min. PMID:26775100

  16. Antireflection and SiO2 Surface Passivation by Liquid-Phase Chemistry for Efficient Black Silicon Solar Cells: Preprint

    SciTech Connect

    Yuan, H. C.; Oh, J.; Zhang, Y.; Kuznetsov, O. A.; Flood, D. J.; Branz, H. M.

    2012-06-01

    We report solar cells with both black Si antireflection and SiO2 surface passivation provided by inexpensive liquid-phase chemistry, rather than by conventional vacuum-based techniques. Preliminary cell efficiency has reached 16.4%. Nanoporous black Si antireflection on crystalline Si by aqueous etching promises low surface reflection for high photon utilization, together with lower manufacturing cost compared to vacuum-based antireflection coating. Ag-nanoparticle-assisted black Si etching and post-etching chemical treatment recently developed at NREL enables excellent control over the pore diameter and pore separation. Performance of black Si solar cells, including open-circuit voltage, short-circuit current density, and blue response, has benefited from these improvements. Prior to this study, our black Si solar cells were all passivated by thermal SiO2 produced in tube furnaces. Although this passivation is effective, it is not yet ideal for ultra-low-cost manufacturing. In this study, we report, for the first time, the integration of black Si with a proprietary liquid-phase deposition (LPD) passivation from Natcore Technology. The Natcore LPD forms a layer of <10-nm SiO2 on top of the black Si surface in a relatively mild chemical bath at room temperature. We demonstrate black Si solar cells with LPD SiO2 with a spectrum-weighted average reflection lower than 5%, similar to the more costly thermally grown SiO2 approach. However, LPD SiO2 provides somewhat better surface-passivation quality according to the lifetime analysis by the photo-conductivity decay measurement. Moreover, black Si solar cells with LPD SiO2 passivation exhibit higher spectral response at short wavelength compared to those passivated by thermally grown SiO2. With further optimization, the combination of aqueous black Si etching and LPD could provide a pathway for low-cost, high-efficiency crystalline Si solar cells.

  17. Investigation of Electrical and Optical Properties of Highly Transparent TCO/Ag/TCO Multilayer.

    PubMed

    Kim, Sunbo; Lee, Jaehyeong; Dao, Vinh Ai; Ahn, Shihyun; Hussain, Shahzada Qamar; Park, Jinjoo; Jung, Junhee; Lee, Chan; Song, Bong-Shik; Choi, Byoungdeog; Lee, Youn-Jung; Iftiquar, S M; Yi, Junsin

    2015-03-01

    Transparent conductive oxides (TCOs) have been widely used as transparent electrodes for opto-electronic devices, such as solar cells, flat-panel displays, and light-emitting diodes, because of their unique characteristics of high optical transmittance and low electrical resistivity. Among various TCO materials, zinc oxide based films have recently received much attention because they have advantages over commonly used indium and tin-based oxide films. Most TCO films, however, exhibit valleys of transmittance in the wavelength range of 550-700 nm, lowering the average transmittance in the visible region and decreasing short-circuit current (Isc) of solar cells. A TCO/Ag/TCO multi-layer structure has emerged as an attractive alternative because it provides optical characteristics without the valley of transmittance compared with a 100-nm-thick single-layer TCO. In this article, we report the electrical, optical and surface properties of TCO/Ag/TCO. These multi-layers were deposited at room temperature with various Ag film thicknesses from 5 to 15 nm while the thickness of TCO thin film was fixed at 40 nm. The TCO/Ag/TCO multi-layer with a 10-nm-thick Ag film showed optimum transmittance in the visible (400-800 nm) wavelength region. These multi-layer structures have advantages over TCO layers of the same thickness. PMID:26413647

  18. Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic Properties

    PubMed Central

    Qu, Yongquan; Xue, Teng; Zhong, Xing; Lin, Yung-Chen; Liao, Lei; Choi, Jina; Duan, Xiangfeng

    2010-01-01

    Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. We show that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. We further demonstrated that the Pt/Si/Ag diodes exhibited highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol were used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. PMID:21629399

  19. Antibacterial activity and reusability of CNT-Ag and GO-Ag nanocomposites

    NASA Astrophysics Data System (ADS)

    Kim, Ji Dang; Yun, Hyosuk; Kim, Gwui Cheol; Lee, Chul Won; Choi, Hyun Chul

    2013-10-01

    A facile approach to the synthesis of novel CNT-Ag and GO-Ag antibacterial materials, in which thiol groups are utilized as linkers to secure silver (Ag) nanoparticles to the CNT and GO surfaces without agglomeration, is reported. The resulting CNT-Ag and GO-Ag samples were characterized by performing TEM, XRD, Auger, XPS, and Raman measurements, which revealed that in these antibacterial materials size-similar and quasi-spherical Ag nanoparticles are anchored to the CNT and GO surfaces. The Ag nanoparticles in CNT-Ag and GO-Ag have narrow size distributions with average diameters of 2.6 and 3.5 nm respectively. The antibacterial activities of CNT-Ag and GO-Ag against Escherichia coli were assessed with the paper-disk diffusion method and by determining the minimal inhibitory concentrations (MICs). CNT-Ag was found to have higher antibacterial activity than the reference Ag colloid. Moreover, both CNT-Ag and GO-Ag retain more than 50% of their original antibacterial activities after 20 washes with detergent, which indicates their potential as antibacterial materials for laboratory and medical purposes.

  20. Comparative Study of Antimicrobial Activity of AgBr and Ag Nanoparticles (NPs)

    PubMed Central

    Suchomel, Petr; Kvitek, Libor; Panacek, Ales; Prucek, Robert; Hrbac, Jan; Vecerova, Renata; Zboril, Radek

    2015-01-01

    The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60–70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120–130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends – the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains. PMID:25781988

  1. An ultrathin, smooth, and low-loss Al-doped Ag film and its application as a transparent electrode in organic photovoltaics.

    PubMed

    Zhang, Cheng; Zhao, Dewei; Gu, Deen; Kim, Hyunsoo; Ling, Tao; Wu, Yi-Kuei Ryan; Guo, L Jay

    2014-08-27

    An ultrathin, smooth, and low-loss Ag film without a wetting layer is achieved by co-depositing a small amount of Al into Ag. The film can be as thin as 6 nm, with a roughness below 1 nm and excellent mechanical flexibility. Organic photovoltaics that use these thin films as transparent electrode show superior efficiency to their indium tin oxide (ITO) counterparts because of improved photon management. PMID:24943876

  2. Enhanced photoelectrochemical and photocatalytic activity in visible-light-driven Ag/BiVO4 inverse opals

    NASA Astrophysics Data System (ADS)

    Fang, Liang; Nan, Feng; Yang, Ying; Cao, Dawei

    2016-02-01

    BiVO4 photonic crystal inverse opals (io-BiVO4) with highly dispersed Ag nanoparticles (NPs) were prepared by the nanosphere lithography method combining the pulsed current deposition method. The incorporation of the Ag NPs can significantly improve the photoelectrochemical and photocatalytic activity of BiVO4 inverse opals in the visible light region. The photocurrent density of the Ag/io-BiVO4 sample is 4.7 times higher than that of the disordered sample without the Ag NPs, while the enhancement factor of the corresponding kinetic constant in photocatalytic experiment is approximately 3. The improved photoelectrochemical and photocatalytic activity is benefited from two reasons: one is the enhanced light harvesting owing to the coupling between the slow light and localized surface plasmon resonance effect; the other is the efficient separation of charge carriers due to the Schottky barriers.

  3. Status of soft photons in experiment E855

    SciTech Connect

    Woody, C.; Lissauer, D. ); Gomez del Campo, J.; Ray, A.; Shapira, D.; Tincknell, M. ); Clark, R. ); Erd, C.; Schukraft, J.; Willis, W. )

    1990-01-01

    Experiment E855 was carried out at the AGS at Brookhaven National Laboratory to study soft photon production near center of mass rapidity Y{sub cm} {approximately} 0 in proton-nucleus collisions at 10 at 18 GeV/c. This was the first dedicated experiment to study this phenomenon at these lower energies. It is important to note that the related process of low mass dilepton pair production has been studied extensively at these energies and an excess signal of dileptons above known hadronic backgrounds has been firmly established. E855 was designed to measure photon production from P{sub t} {approximately} 5 MeV/c up to several GeV/c. A search will be made for an excess of soft photons in the P{sub t} region below the Jacobian peak from {pi}{sup 0} decays, above that which is expected from hadronic bremsstrahlung. Any observed signal will be correlated with the total charged multiplicity in the event in order to determine its production mechanism. This correlation can be used to distinguish purely hadronic sources of soft photons, such as mesons decays and bremsstrahlung, which vary linearly with the charged multiplicity, and a thermal source of soft photons which would exhibit a quadratic dependence on the charged multiplicity. In addition, E855 will measure low energy photons from nuclear decays which can be a background for measuring soft photons near Y{sub cm} {approximately} 0. These photons are also interesting from a nuclear physics point of view, since the spectrum of photons from nuclei excited by incident high energy protons gives a measure of the temperature of the excited nucleus and the amount of excitation energy which can be transferred to a nucleus in a high energy proton collision.

  4. Photon beam position monitor

    DOEpatents

    Kuzay, Tuncer M.; Shu, Deming

    1995-01-01

    A photon beam position monitor for use in the front end of a beamline of a high heat flux and high energy photon source such as a synchrotron radiation storage ring detects and measures the position and, when a pair of such monitors are used in tandem, the slope of a photon beam emanating from an insertion device such as a wiggler or an undulator inserted in the straight sections of the ring. The photon beam position monitor includes a plurality of spaced blades for precisely locating the photon beam, with each blade comprised of chemical vapor deposition (CVD) diamond with an outer metal coating of a photon sensitive metal such as tungsten, molybdenum, etc., which combination emits electrons when a high energy photon beam is incident upon the blade. Two such monitors are contemplated for use in the front end of the beamline, with the two monitors having vertically and horizontally offset detector blades to avoid blade "shadowing". Provision is made for aligning the detector blades with the photon beam and limiting detector blade temperature during operation.

  5. Photon beam position monitor

    DOEpatents

    Kuzay, T.M.; Shu, D.

    1995-02-07

    A photon beam position monitor is disclosed for use in the front end of a beamline of a high heat flux and high energy photon source such as a synchrotron radiation storage ring detects and measures the position and, when a pair of such monitors are used in tandem, the slope of a photon beam emanating from an insertion device such as a wiggler or an undulator inserted in the straight sections of the ring. The photon beam position monitor includes a plurality of spaced blades for precisely locating the photon beam, with each blade comprised of chemical vapor deposition (CVD) diamond with an outer metal coating of a photon sensitive metal such as tungsten, molybdenum, etc., which combination emits electrons when a high energy photon beam is incident upon the blade. Two such monitors are contemplated for use in the front end of the beamline, with the two monitors having vertically and horizontally offset detector blades to avoid blade ''shadowing''. Provision is made for aligning the detector blades with the photon beam and limiting detector blade temperature during operation. 18 figs.

  6. Photonic layered media

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu

    2002-01-01

    A new class of structured dielectric media which exhibit significant photonic bandstructure has been invented. The new structures, called photonic layered media, are easy to fabricate using existing layer-by-layer growth techniques, and offer the ability to significantly extend our practical ability to tailor the properties of such optical materials.

  7. Solar Cookers.

    ERIC Educational Resources Information Center

    King, Richard C.

    1981-01-01

    Describes the use of solar cookers in the science classroom. Includes instructions for construction of a solar cooker, an explanation of how solar cookers work, and a number of suggested activities. (DS)

  8. Synthesis of surface plasmon resonance (SPR) triggered Ag/TiO2 photocatalyst for degradation of endocrine disturbing compounds

    NASA Astrophysics Data System (ADS)

    Leong, Kah Hon; Gan, Bee Ling; Ibrahim, Shaliza; Saravanan, Pichiah

    2014-11-01

    Surface deposition of silver nanoparticles (Ag NPs) onto the 100% anatase titania (Ag/TiO2) for evolution of surface plasmon resonance (SPR) was achieved sustainably with the assistance of solar energy. The preparation resulted in Ag/TiO2 photocatalyst with varied Ag depositions (0.5 wt%, 1.0 wt%, 3.0 wt% and 5.0 wt%). All obtained photocatalysts were characterized for the evolution of SPR via crystalline phase analysis, morphology, lattice fringes, surface area and pore size characteristics, chemical composition with chemical and electronic state, Raman scattering, optical and photoluminescence properties. The deposition of synthesized Ag NPs exhibited high uniformity and homogeneity and laid pathway for effective utilization of the visible region of electromagnetic spectrum through SPR. The depositions also lead for suppressing recombination rates of electron-hole. The photocatalytic evaluation was carried out by adopting two different class of endocrine disturbing compound (EDC) i.e., amoxicillin (pharmaceutical) and 2,4-dichlorophenol (pesticide) excited with artificial visible light source. Ag/TiO2 with Ag > 0.5 wt% exhibited significant degradation efficiency for both amoxicillin and 2,4-dichlorophenol. Thus synthesized Ag/TiO2 revealed the implication of plasmonics on TiO2 for the enhanced visible light photocatalytic activity.

  9. Surface-enhanced Raman scattering of a Ag/oligo(phenyleneethynylene)/Ag sandwich

    NASA Astrophysics Data System (ADS)

    Fletcher, Melissa; Alexson, D. M.; Prokes, Sharka; Glembocki, Orest; Vivoni, Alberto; Hosten, Charles

    2011-02-01

    α,ω-Dithiols are a useful class of compounds in molecular electronics because of their ability to easily adsorb to two metal surfaces, producing a molecular junction. We have prepared Ag nanosphere/oligo(phenyleneethynylene)/Ag sol (AgNS/OPE/Ag sol) and Ag nanowire/oligo(phenyleneethynylene)/Ag sol (AgNW/OPE/Ag sol) sandwiches to simulate the architecture of a molecular electronic device. This was achieved by self-assembly of OPE on the silver nanosurface, deprotection of the terminal sulfur, and deposition of Ag sol atop the monolayer. These sandwiches were then characterized by surface-enhanced Raman scattering (SERS) spectroscopy. The resulting spectra were compared to the bulk spectrum of the dimer and to the Ag nanosurface/OPE SERS spectra. The intensities of the SERS spectra in both systems exhibit a strong dependence on Ag deposition time and the results are also suggestive of intense interparticle coupling of the electromagnetic fields in both the AgNW/OPE/Ag and the AgNS/OPE/Ag systems. Three previously unobserved bands (1219, 1234, 2037 cm -1) arose in the SER spectra of the sandwiches and their presence is attributed to the strong enhancement of the electromagnetic field which is predicted from the COSMOL computational package. The 544 cm -1 disulfide bond which is observed in the spectrum of solid OPE but is absent in the AgNS/OPE/Ag and AgNW/OPE/Ag spectra is indicative of chemisorption of OPE to the nanoparticles through oxidative dissociation of the disulfide bond.

  10. Plasmon-enhanced two-photon-induced isomerization for highly-localized light-based actuation of inorganic/organic interfaces.

    PubMed

    Lim, Chang-Keun; Li, Xin; Li, Yue; Drew, Kurt L M; Palafox-Hernandez, J Pablo; Tang, Zhenghua; Baev, Alexander; Kuzmin, Andrey N; Knecht, Marc R; Walsh, Tiffany R; Swihart, Mark T; Ågren, Hans; Prasad, Paras N

    2016-02-21

    Two-photon initiated photo-isomerization of an azobenzene moiety adsorbed on silver nanoparticles (Ag NPs) is demonstrated. The azobenzene is linked to a materials-binding peptide that brings it into intimate contact with the Ag NP surface, producing a dramatic enhancement of its two-photon absorbance. An integrated modeling approach, combining advanced conformational sampling with Quantum Mechanics/Capacitance Molecular Mechanics and response theory, shows that charge transfer and image charges in the Ag NP generate local fields that enhance two-photon absorption of the cis isomer, but not the trans isomer, of adsorbed molecules. Moreover, dramatic local field enhancement is expected near the localized surface plasmon resonance (LSPR) wavelength, and the LSPR band of the Ag NPs overlaps the azobenzene absorbance that triggers cis to trans switching. As a result, the Ag NPs enable two-photon initiated cis to trans isomerization, but not trans to cis isomerization. Confocal anti-Stokes fluorescence imaging shows that this effect is not due to local heating, while the quadratic dependence of switching rate on laser intensity is consistent with a two-photon process. Highly localized two-photon initiated switching could allow local manipulation near the focal point of a laser within a 3D nanoparticle assembly, which cannot be achieved using linear optical processes. PMID:26830974

  11. A novel photonic oscillator

    NASA Technical Reports Server (NTRS)

    Yao, X. S.; Maleki, L.

    1995-01-01

    We report a novel oscillator for photonic RF systems. This oscillator is capable of generating high-frequency signals up to 70 GHz in both electrical and optical domains and is a special voltage-controlled oscillator with an optical output port. It can be used to make a phase-locked loop (PLL) and perform all functions that a PLL is capable of for photonic systems. It can be synchronized to a reference source by means of optical injection locking, electrical injection locking, and PLL. It can also be self-phase locked and self-injection locked to generate a high-stability photonic RF reference. Its applications include high-frequency reference regeneration and distribution, high-gain frequency multiplication, comb-frequecy and square-wave generation, carrier recovery, and clock recovery. We anticipate that such photonic voltage-controlled oscillators (VCOs) will be as important to photonic RF systems as electrical VCOs are to electrical RF systems.

  12. Ion photon emission microscope

    DOEpatents

    Doyle, Barney L.

    2003-04-22

    An ion beam analysis system that creates microscopic multidimensional image maps of the effects of high energy ions from an unfocussed source upon a sample by correlating the exact entry point of an ion into a sample by projection imaging of the ion-induced photons emitted at that point with a signal from a detector that measures the interaction of that ion within the sample. The emitted photons are collected in the lens system of a conventional optical microscope, and projected on the image plane of a high resolution single photon position sensitive detector. Position signals from this photon detector are then correlated in time with electrical effects, including the malfunction of digital circuits, detected within the sample that were caused by the individual ion that created these photons initially.

  13. Solar energy conversion.

    SciTech Connect

    Crabtree, G. W.; Lewis, N. S.

    2008-03-01

    If solar energy is to become a practical alternative to fossil fuels, we must have efficient ways to convert photons into electricity, fuel, and heat. The need for better conversion technologies is a driving force behind many recent developments in biology, materials, and especially nanoscience. The Sun has the enormous untapped potential to supply our growing energy needs. The barrier to greater use of the solar resource is its high cost relative to the cost of fossil fuels, although the disparity will decrease with the rising prices of fossil fuels and the rising costs of mitigating their impact on the environment and climate. The cost of solar energy is directly related to the low conversion efficiency, the modest energy density of solar radiation, and the costly materials currently required. The development of materials and methods to improve solar energy conversion is primarily a scientific challenge: Breakthroughs in fundamental understanding ought to enable marked progress. There is plenty of room for improvement, since photovoltaic conversion efficiencies for inexpensive organic and dye-sensitized solar cells are currently about 10% or less, the conversion efficiency of photosynthesis is less than 1%, and the best solar thermal efficiency is 30%. The theoretical limits suggest that we can do much better. Solar conversion is a young science. Its major growth began in the 1970s, spurred by the oil crisis that highlighted the pervasive importance of energy to our personal, social, economic, and political lives. In contrast, fossil-fuel science has developed over more than 250 years, stimulated by the Industrial Revolution and the promise of abundant fossil fuels. The science of thermodynamics, for example, is intimately intertwined with the development of the steam engine. The Carnot cycle, the mechanical equivalent of heat, and entropy all played starring roles in the development of thermodynamics and the technology of heat engines. Solar-energy science faces

  14. Roadmap on silicon photonics

    NASA Astrophysics Data System (ADS)

    Thomson, David; Zilkie, Aaron; Bowers, John E.; Komljenovic, Tin; Reed, Graham T.; Vivien, Laurent; Marris-Morini, Delphine; Cassan, Eric; Virot, Léopold; Fédéli, Jean-Marc; Hartmann, Jean-Michel; Schmid, Jens H.; Xu, Dan-Xia; Boeuf, Frédéric; O’Brien, Peter; Mashanovich, Goran Z.; Nedeljkovic, M.

    2016-07-01

    Silicon photonics research can be dated back to the 1980s. However, the previous decade has witnessed an explosive growth in the field. Silicon photonics is a disruptive technology that is poised to revolutionize a number of application areas, for example, data centers, high-performance computing and sensing. The key driving force behind silicon photonics is the ability to use CMOS-like fabrication resulting in high-volume production at low cost. This is a key enabling factor for bringing photonics to a range of technology areas where the costs of implementation using traditional photonic elements such as those used for the telecommunications industry would be prohibitive. Silicon does however have a number of shortcomings as a photonic material. In its basic form it is not an ideal material in which to produce light sources, optical modulators or photodetectors for example. A wealth of research effort from both academia and industry in recent years has fueled the demonstration of multiple solutions to these and other problems, and as time progresses new approaches are increasingly being conceived. It is clear that silicon photonics has a bright future. However, with a growing number of approaches available, what will the silicon photonic integrated circuit of the future look like? This roadmap on silicon photonics delves into the different technology and application areas of the field giving an insight into the state-of-the-art as well as current and future challenges faced by researchers worldwide. Contributions authored by experts from both industry and academia provide an overview and outlook for the silicon waveguide platform, optical sources, optical modulators, photodetectors, integration approaches, packaging, applications of silicon photonics and approaches required to satisfy applications at mid-infrared wavelengths. Advances in science and technology required to meet challenges faced by the field in each of these areas are also addressed together with

  15. Visualizing Redox Dynamics of a Single Ag/AgCl Heterogeneous Nanocatalyst at Atomic Resolution.

    PubMed

    Wu, Yimin A; Li, Liang; Li, Zheng; Kinaci, Alper; Chan, Maria K Y; Sun, Yugang; Guest, Jeffrey R; McNulty, Ian; Rajh, Tijana; Liu, Yuzi

    2016-03-22

    Operando characterization of gas-solid reactions at the atomic scale is of great importance for determining the mechanism of catalysis. This is especially true in the study of heterostructures because of structural correlation between the different parts. However, such experiments are challenging and have rarely been accomplished. In this work, atomic scale redox dynamics of Ag/AgCl heterostructures have been studied using in situ environmental transmission electron microscopy (ETEM) in combination with density function theory (DFT) calculations. The reduction of Ag/AgCl to Ag is likely a result of the formation of Cl vacancies while Ag(+) ions accept electrons. The oxidation process of Ag/AgCl has been observed: rather than direct replacement of Cl by O, the Ag/AgCl nanocatalyst was first reduced to Ag, and then Ag was oxidized to different phases of silver oxide under different O2 partial pressures. Ag2O formed at low O2 partial pressure, whereas AgO formed at atmospheric pressure. By combining in situ ETEM observation and DFT calculations, this structural evolution is characterized in a distinct nanoscale environment. PMID:26937679

  16. Photonics Research and Development

    SciTech Connect

    Dickson, Elizabeth

    2010-01-15

    During the period August 2005 through October 2009, the UNLV Research Foundation (UNLVRF), a non-profit affiliate of the University of Nevada, Las Vegas (UNLV), in collaboration with UNLV's Colleges of Science and Engineering; Boston University (BU); Oak Ridge National Laboratory (ORNL); and Sunlight Direct, LLC, has managed and conducted a diverse and comprehensive research and development program focused on light-emitting diode (LED) technologies that provide significantly improved characteristics for lighting and display applications. This final technical report provides detailed information on the nature of the tasks, the results of the research, and the deliverables. It is estimated that about five percent of the energy used in the nation is for lighting homes, buildings and streets, accounting for some 25 percent of the average home's electric bill. However, the figure is significantly higher for the commercial sector. About 60 percent of the electricity for businesses is for lighting. Thus replacement of current lighting with solid-state lighting technology has the potential to significantly reduce this nation's energy consumption by some estimates, possibly as high as 20%. The primary objective of this multi-year R&D project has been to develop and advance lighting technologies to improve national energy conversion efficiencies; reduce heat load; and significantly lower the cost of conventional lighting technologies. The UNLVRF and its partners have specifically focused these talents on (1) improving LED technologies; (2) optimizing hybrid solar lighting, a technology which potentially offers the benefits of blending natural with artificial lighting systems, thus improving energy efficiency; and (3) building a comprehensive academic infrastructure within UNLV which concentrates on photonics R&D. Task researchers have reported impressive progress in (1) the development of quantum dot laser emitting diodes (QDLEDs) which will ultimately improve energy

  17. Indistinguishability of independent single photons

    NASA Astrophysics Data System (ADS)

    Sun, F. W.; Wong, C. W.

    2009-01-01

    The indistinguishability of independent single photons is presented by decomposing the single photon pulse into the mixed state of different transform-limited pulses. The entanglement between single photons and outer environment or other photons induces the distribution of the center frequencies of those transform-limited pulses and makes photons distinguishable. Only the single photons with the same transform-limited form are indistinguishable. In details, the indistinguishability of single photons from the solid-state quantum emitter and spontaneous parametric down-conversion is examined with two-photon Hong-Ou-Mandel interferometer. Moreover, experimental methods to enhance the indistinguishability are discussed, where the usage of spectral filter is highlighted.

  18. Evolution of the symbiotic binary system AG Dranconis

    NASA Technical Reports Server (NTRS)

    Mikolajewska, Joanna; Kenyon, Scott J; Mikolajewski, Maciej; Garcia, Michael R.; Polidan, Ronald S.

    1995-01-01

    We present an analysis of new and archival photometric and spectroscopic observations of the symbiotic star AG Draconis. This binary has undergone several 1 - 3 mag optical and ultraviolet eruptions during the past 15 years. Our combination of optical and ultraviolet spectroscopic data allow a more complete analysis of this system than in previous papers. AG Dra is composed of a K-type bright giant M(sub g) approximately 1.5 solar mass) and a hot, compact star M(sub h approximatelly 0.4 - 0.6 solar mass) embedded in a dense, low metallicity nebula. The hot component undergoes occasional thermonuclear runaways that produce 2 - 3 mag optical/ultraviolet eruptions. During these eruptions, the hot component develops a low velocity wind that quenches x-ray emission from the underlying hot white dwarf. The photoionized nebula changes its volume by a factor of 5 throughout an eruptin cycle. The K bright giant occults low ionization emission lines during superior conjunctions at all outburst phases but does not occult high ionization lines in outburst (and perhaps quiescence). This geometry and the component masses suggest a system inclination of i approximately 30 deg - 45 deg.

  19. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells.

    PubMed

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-28

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ∼80% at 550 nm and sheet resistance of 18 Ω sq(-1). Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process. PMID:26465213

  20. Photon management with index-near-zero materials

    NASA Astrophysics Data System (ADS)

    Wang, Zhu; Wang, Ziyu; Yu, Zongfu

    2016-08-01

    Index-near-zero materials can be used for effective photon management. They help to restrict the angle of acceptance, resulting in greatly enhanced light trapping limit. In addition, these materials also decrease the radiative recombination, leading to enhanced open circuit voltage and energy efficiency in direct bandgap solar cells.

  1. Direct Photons at RHIC

    SciTech Connect

    Gabor,D.

    2008-07-29

    Direct photons are ideal tools to investigate kinematical and thermodynamical conditions of heavy ion collisions since they are emitted from all stages of the collision and once produced they leave the interaction region without further modification by the medium. The PHENIX experiment at RHIC has measured direct photon production in p+p and Au+Au collisions at 200 GeV over a wide transverse momentum (p{sub T}) range. The p+p measurements allow a fundamental test of QCD, and serve as a baseline when we try to disentangle more complex mechanisms producing high p{sub T} direct photons in Au+Au. As for thermal photons in Au+Au we overcome the difficulties due to the large background from hadronic decays by measuring 'almost real' virtual photons which appear as low invariant mass e{sup +}e{sup -} pairs: a significant excess of direct photons is measured above the above next-to-leading order perturbative quantum chromodynamics calculations. Additional insights on the origin of direct photons can be gained with the study of the azimuthal anisotropy which benefits from the increased statistics and reaction plane resolution achieved in RHIC Year-7 data.

  2. Multi-Layer Inkjet Printed Contacts for Silicon Solar Cells

    SciTech Connect

    Curtis, C. J.; van Hest, M.; Miedaner, A.; Kaydanova, T.; Smith, L.; Ginley, D. S.

    2006-01-01

    Ag, Cu, and Ni metallizations were inkjet printed with near vacuum deposition quality. The approach developed can be easily extended to other conductors such as Pt, Pd, Au, etc. Thick highly conducting lines of Ag and Cu demonstrating good adhesion to glass, Si, and printed circuit board (PCB) have been printed at 100-200degC in air and N{sub 2} respectively. Ag grids were inkjet-printed on Si solar cells and fired through the silicon nitride AR layer at 850degC, resulting in 8% cells. Next generation inks, including an ink that etches silicon nitride, have now been developed. Multi-layer inkjet printing of the etching ink followed by Ag ink produced contacts under milder conditions and gave solar cells with efficiencies as high as 12%.

  3. Visible emission from Ag+ exchanged SOD zeolites

    NASA Astrophysics Data System (ADS)

    Lin, H.; Imakita, K.; Fujii, M.; Prokof'ev, V. Yu.; Gordina, N. E.; Saïd, B.; Galarneau, A.

    2015-09-01

    Broad visible emissions dominant at green or red have been observed for the thermally-treated Ag+ exchanged SOD zeolites, determined by the Ag+ loading contents and the excitation wavelengths. Contrary to the notable reversible green/red dominant emission evolution in the Ag+ exchanged LTA zeolites upon hydration/dehydration in air (or water vapor)/vacuum, emission spectra of the Ag+ exchanged SOD zeolites are insensitive to the environmental change. This is most probably due to the difficult H2O permeation in SOD zeolites in comparison with LTA zeolites. By combining the environment dependent emission spectra of the Ag+ exchanged LTA and SOD zeolites, we proposed the following emission mechanisms for Ag+ exchanged LTA and SOD zeolites: the green emission is due to the transition from ligand-to-metal (framework O2- --> Ag+) charge transfer state to the ground state and the red emission is due to the transition from the metal-metal (Ag+-Ag+) charge transfer state to the ground state. The insensitive environment dependent emission characteristics of Ag+ exchanged SOD zeolites may have potential applications as robust phosphors.

  4. Size-dependent cytotoxicity of silver nanoparticles in human lung cells: the role of cellular uptake, agglomeration and Ag release

    PubMed Central

    2014-01-01

    Background Silver nanoparticles (AgNPs) are currently one of the most manufactured nanomaterials. A wide range of toxicity studies have been performed on various AgNPs, but these studies report a high variation in toxicity and often lack proper particle characterization. The aim of this study was to investigate size- and coating-dependent toxicity of thoroughly characterized AgNPs following exposure of human lung cells and to explore the mechanisms of toxicity. Methods BEAS-2B cells were exposed to citrate coated AgNPs of different primary particle sizes (10, 40 and 75 nm) as well as to 10 nm PVP coated and 50 nm uncoated AgNPs. The particle agglomeration in cell medium was investigated by photon cross correlation spectroscopy (PCCS); cell viability by LDH and Alamar Blue assay; ROS induction by DCFH-DA assay; genotoxicity by alkaline comet assay and γH2AX foci formation; uptake and intracellular localization by transmission electron microscopy (TEM); and cellular dose as well as Ag release by atomic absorption spectroscopy (AAS). Results The results showed cytotoxicity only of the 10 nm particles independent of surface coating. In contrast, all AgNPs tested caused an increase in overall DNA damage after 24 h assessed by the comet assay, suggesting independent mechanisms for cytotoxicity and DNA damage. However, there was no γH2AX foci formation and no increased production of intracellular reactive oxygen species (ROS). The reasons for the higher toxicity of the 10 nm particles were explored by investigating particle agglomeration in cell medium, cellular uptake, intracellular localization and Ag release. Despite different agglomeration patterns, there was no evident difference in the uptake or intracellular localization of the citrate and PVP coated AgNPs. However, the 10 nm particles released significantly more Ag compared with all other AgNPs (approx. 24 wt% vs. 4–7 wt%) following 24 h in cell medium. The released fraction in cell medium did not induce any

  5. Plasmonic enhanced optical characteristics of Ag nanostructured ZnO thin films

    NASA Astrophysics Data System (ADS)

    Sarkar, Arijit; Gogurla, Narendar; Shivakiran Bhaktha, B. N.; Ray, Samit K.

    2016-04-01

    We have demonstrated the enhanced photoluminescence and photoconducting characteristics of plasmonic Ag–ZnO films due to the light scattering effect from Ag nanoislands. Ag nanoislands have been prepared on ITO-coated glass substrates by thermal evaporation followed by annealing. Plasmonic Ag–ZnO films have been fabricated by depositing ZnO over Ag nanoislands by sol–gel process. The band-edge emission of ZnO is enhanced for 170 nm sized Ag nanoislands in ZnO as compared to pure ZnO. The defect emission is also found to be quenched simultaneously for plasmonic Ag–ZnO films. The enhancement and quenching of photoluminescence at different wavelengths for Ag–ZnO films can be well understood from the localized surface plasmon resonance of Ag nanoislands. The Ag–ZnO M–S–M photoconductor device showed a tenfold increment in photocurrent and faster photoresponse as compared to the control ZnO device. The enhancement in photoresponse of the device is due to the increased photon absorption in ZnO films via scattering of the incident illumination.

  6. Bright two-photon emission and ultra-fast relaxation dynamics in a DNA-templated nanocluster investigated by ultra-fast spectroscopy

    NASA Astrophysics Data System (ADS)

    Yau, Sung Hei; Abeyasinghe, Neranga; Orr, Meghan; Upton, Leslie; Varnavski, Oleg; Werner, James H.; Yeh, Hsin-Chih; Sharma, Jaswinder; Shreve, Andrew P.; Martinez, Jennifer S.; Goodson, Theodore, III

    2012-06-01

    Metal nanoclusters have interesting steady state fluorescence emission, two-photon excited emission and ultrafast dynamics. A new subclass of fluorescent silver nanoclusters (Ag NCs) are NanoCluster Beacons. NanoCluster Beacons consist of a weakly emissive Ag NC templated on a single stranded DNA (``Ag NC on ssDNA'') that becomes highly fluorescent when a DNA enhancer sequence is brought in proximity to the Ag NC by DNA base pairing (``Ag NC on dsDNA''). Steady state fluorescence was observed at 540 nm for both Ag NC on ssDNA and dsDNA; emission at 650 nm is observed for Ag NC on dsDNA. The emission at 550 nm is eight times weaker than that at 650 nm. Fluorescence up-conversion was used to study the dynamics of the emission. Bi-exponential fluorescence decay was recorded at 550 nm with lifetimes of 1 ps and 17 ps. The emission at 650 nm was not observed at the time scale investigated but has been reported to have a lifetime of 3.48 ns. Two-photon excited fluorescence was detected for Ag NC on dsDNA at 630 nm when excited at 800 nm. The two-photon absorption cross-section was calculated to be ~3000 GM. Femtosecond transient absorption experiments were performed to investigate the excited state dynamics of DNA-Ag NC. An excited state unique to Ag NC on dsDNA was identified at ~580 nm as an excited state bleach that related directly to the emission at 650 nm based on the excitation spectrum. Based on the optical results, a simple four level system is used to describe the emission mechanism for Ag NC on dsDNA.

  7. Bright two-photon emission and ultra-fast relaxation dynamics in a DNA-templated nanocluster investigated by ultra-fast spectroscopy.

    PubMed

    Yau, Sung Hei; Abeyasinghe, Neranga; Orr, Meghan; Upton, Leslie; Varnavski, Oleg; Werner, James H; Yeh, Hsin-Chih; Sharma, Jaswinder; Shreve, Andrew P; Martinez, Jennifer S; Goodson, Theodore

    2012-07-21

    Metal nanoclusters have interesting steady state fluorescence emission, two-photon excited emission and ultrafast dynamics. A new subclass of fluorescent silver nanoclusters (Ag NCs) are NanoCluster Beacons. NanoCluster Beacons consist of a weakly emissive Ag NC templated on a single stranded DNA ("Ag NC on ssDNA") that becomes highly fluorescent when a DNA enhancer sequence is brought in proximity to the Ag NC by DNA base pairing ("Ag NC on dsDNA"). Steady state fluorescence was observed at 540 nm for both Ag NC on ssDNA and dsDNA; emission at 650 nm is observed for Ag NC on dsDNA. The emission at 550 nm is eight times weaker than that at 650 nm. Fluorescence up-conversion was used to study the dynamics of the emission. Bi-exponential fluorescence decay was recorded at 550 nm with lifetimes of 1 ps and 17 ps. The emission at 650 nm was not observed at the time scale investigated but has been reported to have a lifetime of 3.48 ns. Two-photon excited fluorescence was detected for Ag NC on dsDNA at 630 nm when excited at 800 nm. The two-photon absorption cross-section was calculated to be ∼3000 GM. Femtosecond transient absorption experiments were performed to investigate the excited state dynamics of DNA-Ag NC. An excited state unique to Ag NC on dsDNA was identified at ∼580 nm as an excited state bleach that related directly to the emission at 650 nm based on the excitation spectrum. Based on the optical results, a simple four level system is used to describe the emission mechanism for Ag NC on dsDNA. PMID:22692295

  8. Photonics: Technology project summary

    NASA Technical Reports Server (NTRS)

    Depaula, Ramon P.

    1991-01-01

    Photonics involves the use of light (photons) in conjunction with electronics for applications in communications, computing, control, and sensing. Components used in photonic systems include lasers, optical detectors, optical wave guide devices, fiber optics, and traditional electronic devices. The goal of this program is to develop hybrid optoelectronic devices and systems for sensing, information processing, communications, and control. It is hoped that these new devices will yield at least an order of magnitude improvement in performance over existing technology. The objective of the program is to conduct research and development in the following areas: (1) materials and devices; (2) networking and computing; (3) optical processing/advanced pattern recognition; and (4) sensing.

  9. Photonic Maxwell's Demon.

    PubMed

    Vidrighin, Mihai D; Dahlsten, Oscar; Barbieri, Marco; Kim, M S; Vedral, Vlatko; Walmsley, Ian A

    2016-02-01

    We report an experimental realization of Maxwell's demon in a photonic setup. We show that a measurement at the few-photons level followed by a feed-forward operation allows the extraction of work from intense thermal light into an electric circuit. The interpretation of the experiment stimulates the derivation of an equality relating work extraction to information acquired by measurement. We derive a bound using this relation and show that it is in agreement with the experimental results. Our work puts forward photonic systems as a platform for experiments related to information in thermodynamics. PMID:26894692

  10. Photon detector system

    DOEpatents

    Ekstrom, Philip A.

    1981-01-01

    A photon detector includes a semiconductor device, such as a Schottky barrier diode, which has an avalanche breakdown characteristic. The diode is cooled to cryogenic temperatures to eliminate thermally generated charge carriers from the device. The diode is then biased to a voltage level exceeding the avalanche breakdown threshold level such that, upon receipt of a photon, avalanche breakdown occurs. This breakdown is detected by appropriate circuitry which thereafter reduces the diode bias potential to a level below the avalanche breakdown threshold level to terminate the avalanche condition. Subsequently, the bias potential is reapplied to the diode in preparation for detection of a subsequently received photon.

  11. Photonic Maxwell's Demon

    NASA Astrophysics Data System (ADS)

    Vidrighin, Mihai D.; Dahlsten, Oscar; Barbieri, Marco; Kim, M. S.; Vedral, Vlatko; Walmsley, Ian A.

    2016-02-01

    We report an experimental realization of Maxwell's demon in a photonic setup. We show that a measurement at the few-photons level followed by a feed-forward operation allows the extraction of work from intense thermal light into an electric circuit. The interpretation of the experiment stimulates the derivation of an equality relating work extraction to information acquired by measurement. We derive a bound using this relation and show that it is in agreement with the experimental results. Our work puts forward photonic systems as a platform for experiments related to information in thermodynamics.

  12. Photon collider Higgs factories

    NASA Astrophysics Data System (ADS)

    Telnov, V. I.

    2014-09-01

    The discovery of the Higgs boson (and still nothing else) have triggered appearance of many proposals of Higgs factories for precision measurement of the Higgs properties. Among them there are several projects of photon colliders (PC) without e+e- in addition to PLC based on e+e- linear colliders ILC and CLIC. In this paper, following a brief discussion of Higgs factories physics program I give an overview of photon colliders based on linear colliders ILC and CLIC, and of the recently proposed photon-collider Higgs factories with no e+e- collision option based on recirculation linacs in ring tunnels.

  13. International photonics training: a case study

    NASA Astrophysics Data System (ADS)

    Sporea, Dan; Massa, Nicholas; Donnelly, Judith F.; Hanes, Fenna

    2007-06-01

    From 2004, the Center for Science Education and Training (CSET) participated to the European Union-funded educational network "Hands-on Science". The aim of the Romanian team was to transform teachers and students from end-users of educational aids to active designers and developers of instructional materials. Several science fields were identified, including photonics. The team at CSET is now focusing on: lasers and their applications, optical fiber communications, solar energy as a sustainable source, and the use of optical spectroscopy in physics and chemistry. CSET initiated an international collaboration with the New England Board of Higher Education (NEBHE) in Boston, Mass., when the Center enrolled an experienced Romanian high school science teacher in a twelve-week "Introduction to Photonics" laboratory-based professional development course. The course was developed by NEBHE through an Advanced Technological Education (ATE) program grant from National Science Foundation and is designed for high school and community college educators from both science and technology instructional areas. The paper reports the experience of this international participation which was made possible since the course is delivered via the Internet by Three Rivers Community College, Norwich, Conn. Its impact on photonics education in Romania and the USA is analyzed, as the participant teacher shares her experiences with teachers and faculty in the "Introduction to Photonics" course and with those enrolled into the Romanian "Hands-on-Science" program.

  14. Capacitive deionization of seawater effected by nano Ag and Ag@C on graphene.

    PubMed

    Cai, P-F; Su, C-J; Chang, W-T; Chang, F-C; Peng, C-Y; Sun, I-W; Wei, Y-L; Jou, C-J; Wang, H Paul

    2014-08-30

    Drinking water shortage has become worse in recent decades. A new capacitive deionization (CDI) method for increasing water supplies through the effective desalination of seawater has been developed. Silver as nano Ag and Ag@C which was prepared by carbonization of the Ag(+)-β-cyclodextrin complex at 573 K for 30 min can add the antimicrobial function into the CDI process. The Ag@C and Ag nanoparticles dispersed on reduced graphene oxide (Ag@C/rGO and nano Ag/rGO) were used as the CDI electrodes. The nano Ag/rGO and Ag@C/rGO electrodes can reduce the charging resistant, and enhance the electrosorption capability. Better CDI efficiencies with the nano Ag/rGO and Ag@C/rGO electrodes can therefore be obtained. When reversed the voltage, the electrodes can be recovered up to 90% within 5 min. This work presents the feasibility for the nano Ag and Ag@C on rGO electrodes applied in CDI process to produce drinking water from seawater or saline water. PMID:24928455

  15. Solar explosion

    NASA Astrophysics Data System (ADS)

    Baccei, B. C.

    1981-04-01

    The Solar Energy Research Institute (SERI) and the Department of Energy (DOE) Passive Solar Manufactured Buildings and Solar Home Builders Programs are developing much needed cost and performance data on solar buildings produced by large-volume home builders. These programs also serve as a model on how government can work effectively with industry.

  16. Solar Energy.

    ERIC Educational Resources Information Center

    Eaton, William W.

    Presented is the utilization of solar radiation as an energy resource principally for the production of electricity. Included are discussions of solar thermal conversion, photovoltic conversion, wind energy, and energy from ocean temperature differences. Future solar energy plans, the role of solar energy in plant and fossil fuel production, and…

  17. Solar Geometry

    Atmospheric Science Data Center

    2014-09-25

    Solar Noon (GMT time) The time when the sun is due south in the ... and sunset.   Daylight average of hourly cosine solar zenith angles (dimensionless) The average cosine of the angle ... overhead during daylight hours.   Cosine solar zenith angle at mid-time between sunrise and solar noon ...

  18. Ag nanotubes and Ag/AgCl electrodes in nanoporous membranes.

    PubMed

    Davenport, Matthew; Healy, Ken; Siwy, Zuzanna S

    2011-04-15

    Miniaturization of the entire experimental setup is a key requirement for widespread application of nanodevices. For nanopore biosensing, integrating electrodes onto the nanopore membrane and controlling the pore length is important for reducing the complexity and improving the sensitivity of the system. Here we present a method to achieve these goals, which relies on electroless plating to produce Ag nanotubes in track-etched polymer nanopore templates. By plating from one side only, we create a conductive nanotube that does not span the full length of the pore, and thus can act as a nanoelectrode located inside the nanopore. To give optimal electrochemical behavior for sensing, we coat the Ag nanotube with a layer of AgCl. We characterize the behavior of this nanoelectrode by measuring its current-voltage response and find that, in most cases, the response is asymmetric. The plated nanopores have initial diameters between 100 and 300 nm, thus a range suitable for detection of viruses. PMID:21389573

  19. Solar energy

    NASA Technical Reports Server (NTRS)

    Rapp, D.

    1981-01-01

    The book opens with a review of the patterns of energy use and resources in the United States, and an exploration of the potential of solar energy to supply some of this energy in the future. This is followed by background material on solar geometry, solar intensities, flat plate collectors, and economics. Detailed attention is then given to a variety of solar units and systems, including domestic hot water systems, space heating systems, solar-assisted heat pumps, intermediate temperature collectors, space heating/cooling systems, concentrating collectors for high temperatures, storage systems, and solar total energy systems. Finally, rights to solar access are discussed.

  20. Microwave background constraints on mixing of photons with hidden photons

    SciTech Connect

    Mirizzi, Alessandro; Redondo, Javier; Sigl, Guenter E-mail: javier.redondo@desy.de

    2009-03-15

    Various extensions of the Standard Model predict the existence of hidden photons kinetically mixing with the ordinary photon. This mixing leads to oscillations between photons and hidden photons, analogous to the observed oscillations between different neutrino flavors. In this context, we derive new bounds on the photon-hidden photon mixing parameters using the high precision cosmic microwave background spectral data collected by the Far Infrared Absolute Spectrophotometer instrument on board of the Cosmic Background Explorer. Requiring the distortions of the CMB induced by the photon-hidden photon mixing to be smaller than experimental upper limits, this leads to a bound on the mixing angle {chi}{sub 0} {approx}< 10{sup -7}-10{sup -5} for hidden photon masses between 10{sup -14} eV and 10{sup -7} eV. This low-mass and low-mixing region of the hidden photon parameter space was previously unconstrained.

  1. Facile synthesis of S–Ag nanocomposites and Ag2S short nanorods by the interaction of sulfur with AgNO3 in PEG400

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Li; Xie, Xin-Yuan; Liang, Ming; Xie, Shu-Ming; Chen, Jie-Mei; Zheng, Wen-Jie

    2016-06-01

    A facile, eco-friendly and inexpensive method to prepare Ag2S short nanorods and S–Ag nanocomposites using sublimed sulfur, AgNO3, PVP and PEG400 was studied. According to x-ray diffraction and scanning electron microscopy of the Ag2S, the products are highly crystalline and pure Ag2S nanorods with diameters of 70–160 nm and lengths of 200–360 nm. X-ray diffraction of the S–Ag nanocomposites shows that we obtained cubic Ag and S nanoparticles. Transmission electron microscopy shows that the molar ratio of PVP to Ag+ plays an important role in controlling the size and morphology of the S–Ag nanocomposites. When the molar ratio of PVP to Ag+ was 10:1, smaller sizes, better dispersibility and narrower distribution of S–Ag nanocomposites with diameters of 10–40 nm were obtained. The formation mechanism of the S–Ag nanocomposites was studied by designing a series of experiments using ultraviolet–visible measurement, and it was found that S nanoparticles are produced first and act as seed crystals; then Ag+ becomes Ag nanocrystals on the surfaces of the S nanoparticles by the reduction of PVP. PEG400 acts as a catalyzer, accelerating the reaction rate, and protects the S–Ag nanocomposites from reacting to produce Ag2S. The antimicrobial experiments show that the S–Ag nanocomposites have greater antimicrobial activity on Staphylococcus aureus, Aspergillus niger and blue mold than Ag nanoparticles.

  2. Photonic band gap materials

    SciTech Connect

    Soukoulis, C.M. |

    1993-12-31

    An overview of the theoretical and experimental efforts in obtaining a photonic band gap, a frequency band in three-dimensional dielectric structures in which electromagnetic waves are forbidden, is presented.

  3. Biophotonics: Circadian photonics

    NASA Astrophysics Data System (ADS)

    Rea, Mark S.

    2011-05-01

    A growing body of medical evidence suggests that disrupting the body's biological clock can have adverse effects on health. Researchers are now creating the photonic tools to monitor, predict and influence the circadian rhythm.

  4. Smart packaging for photonics

    SciTech Connect

    Smith, J.H.; Carson, R.F.; Sullivan, C.T.; McClellan, G.; Palmer, D.W.

    1997-09-01

    Unlike silicon microelectronics, photonics packaging has proven to be low yield and expensive. One approach to make photonics packaging practical for low cost applications is the use of {open_quotes}smart{close_quotes} packages. {open_quotes}Smart{close_quotes} in this context means the ability of the package to actuate a mechanical change based on either a measurement taken by the package itself or by an input signal based on an external measurement. One avenue of smart photonics packaging, the use of polysilicon micromechanical devices integrated with photonic waveguides, was investigated in this research (LDRD 3505.340). The integration of optical components with polysilicon surface micromechanical actuation mechanisms shows significant promise for signal switching, fiber alignment, and optical sensing applications. The optical and stress properties of the oxides and nitrides considered for optical waveguides and how they are integrated with micromechanical devices were investigated.

  5. Photonics Explorer: revolutionizing photonics in the classroom

    NASA Astrophysics Data System (ADS)

    Prasad, Amrita; Debaes, Nathalie; Cords, Nina; Fischer, Robert; Vlekken, Johan; Euler, Manfred; Thienpont, Hugo

    2012-10-01

    The `Photonics Explorer' is a unique intra-curricular optics kit designed to engage, excite and educate secondary school students about the fascination of working with light - hands-on, in their own classrooms. Developed with a pan European collaboration of experts, the kit equips teachers with class sets of experimental material provided within a supporting didactic framework, distributed in conjunction with teacher training courses. The material has been specifically designed to integrate into European science curricula. Each kit contains robust and versatile components sufficient for a class of 25-30 students to work in groups of 2-3. The didactic content is based on guided inquiry-based learning (IBL) techniques with a strong emphasis on hands-on experiments, team work and relating abstract concepts to real world applications. The content has been developed in conjunction with over 30 teachers and experts in pedagogy to ensure high quality and ease of integration. It is currently available in 7 European languages. The Photonics Explorer allows students not only to hone their essential scientific skills but also to really work as scientists and engineers in the classroom. Thus, it aims to encourage more young people to pursue scientific careers and avert the imminent lack of scientific workforce in Europe. 50 Photonics Explorer kits have been successfully tested in 7 European countries with over 1500 secondary school students. The positive impact of the kit in the classroom has been qualitatively and quantitatively evaluated. A non-profit organisation, EYESTvzw [Excite Youth for Engineering Science and Technology], is responsible for the large scale distribution of the Photonics Explorer.

  6. Dispersion in photonic crystals

    NASA Astrophysics Data System (ADS)

    Witzens, Jeremy

    2005-11-01

    Investigations on the dispersive properties of photonic crystals, modified scattering in ring-resonators, monolithic integration of vertical-cavity surface-emitting lasers and advanced data processing techniques for the finite-difference time-domain method are presented. Photonic crystals are periodic mesoscopic arrays of scatterers that modify the propagation properties of electromagnetic waves in a similar way as "natural" crystals modify the properties of electrons in solid-state physics. In this thesis photonic crystals are implemented as planar photonic crystals, i.e., optically thin semiconductor films with periodic arrays of holes etched into them, with a hole-to-hole spacing of the order of the wavelength of light in the dielectric media. Photonic crystals can feature forbidden frequency ranges (the band-gaps) in which light cannot propagate. Even though most work on photonic crystals has focused on these band-gaps for application such as confinement and guiding of light, this thesis focuses on the allowed frequency regions (the photonic bands) and investigates how the propagation of light is modified by the crystal lattice. In particular the guiding of light in bulk photonic crystals in the absence of lattice defects (the self-collimation effect) and the angular steering of light in photonic crystals (the superprism effect) are investigated. The latter is used to design a planar lightwave circuit for frequency domain demultiplexion. Difficulties such as efficient insertion of light into the crystal are resolved and previously predicted limitations on the resolution are circumvented. The demultiplexer is also fabricated and characterized. Monolithic integration of vertical-cavity surface-emitting lasers by means of resonantly enhanced grating couplers is investigated. The grating coupler is designed to bend light through a ninety-degree angle and is characterized with the finite-difference time-domain method. The vertical-cavity surface-emitting lasers are

  7. Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island.

    PubMed

    Xu, Jinxia; Xiao, Xiangheng; Ren, Feng; Wu, Wei; Dai, Zhigao; Cai, Guangxu; Zhang, Shaofeng; Zhou, Juan; Mei, Fei; Jiang, Changzhong

    2012-01-01

    In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO2 film. PMID:22548875

  8. Updates to ISO 21348 (determining solar irradiances)

    NASA Astrophysics Data System (ADS)

    Tobiska, W. Kent

    2012-07-01

    The ISO 21348 (Determining Solar Irradiances) International Standard is going through a document update. A consensus solar spectrum, solar indices/proxies descriptions, solar model descriptions, and solar measurement descriptions are among the Annexes that are proposed to the standard. These topics will be reviewed and described. The International Standards Organization (ISO) published IS 21348 in 2007 after 7 years of development by the international scientific community. In ISO, documents are reviewed on a regular basis and reaffirmed, updated, or deleted according to the votes of national delegations represented in ISO. IS 21348 provides guidelines for specifying the process of determining solar irradiances. Solar irradiances are reported through products such as measurement sets, reference spectra, empirical models, theoretical models and solar irradiance proxies or indices. These products are used in scientific and engineering applications to characterize within the natural space environment solar irradiances that are relevant to space systems and materials. Examples of applications using input solar irradiance energy include the determination of atmospheric densities for spacecraft orbit determination, attitude control and re-entry calculations, as well as for debris mitigation and collision avoidance activity. Direct and indirect pressure from solar irradiance upon spacecraft surfaces also affects attitude control separately from atmospheric density effects. Solar irradiances are used to provide inputs for a) calculations of ionospheric parameters, b) photon-induced radiation effects, and c) radiative transfer modeling of planetary atmospheres. Input solar irradiance energy is used to characterize material properties related to spacecraft thermal control, including surface temperatures, reflectivity, absorption and degradation. Solar energy applications requiring a standard process for determining solar irradiance energy include i) solar cell power

  9. Ultrastable Multigigahertz Photonic Oscillator

    NASA Technical Reports Server (NTRS)

    Logan, Ronald T., Jr.

    1996-01-01

    Novel photonic oscillator developed to serve as ultrastable source of microwave and millimeter-wave signals. In system, oscillations generated photonically, then converted to electronic form. Includes self-mode-locked semiconductor laser producing stream of pulses, detected and fed back to laser as input. System also includes fiber-optic-delay-line discriminator, which detects fluctuations of self-mode-locking frequency and generates error signal used in negative-feedback loop to stabilize pulse-repetition frequency.

  10. Electron irradiation of tandem junction solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Miyahira, T. F.; Scott-Monck, J. A.

    1979-01-01

    The electrical behavior of 100 micron thick tandem junction solar cells manufactured by Texas Instruments was studied as a function of 1 MeV electron fluence, photon irradiation, and 60 C annealing. These cells are found to degrade rapidly with radiation, the most serious loss occurring in the blue end of the cell's spectral response. No photon degradation was found to occur, but the cells did anneal a small amount at 60 C.

  11. Photonic metallic nanostructures in photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Ion, Rodica-Mariana; Fierascu, R. C.; Dumitriu, Irina

    2009-01-01

    Plasmons are resonant modes that involve the interaction between free charges and light. Nanoparticle-based photonic explorers have been developed for photodynamic therapy (PDT). PDT has been widely used in both oncological (e.g., tumors) and nononcological (e.g., age-related macular degeneration, localized infection, and nonmalignant skin conditions) applications. Three primary components are involved in PDT: light, a photosensitizing drug, and oxygen. The photosensitizer adsorbs light energy, which it then transfers to molecular oxygen to create an activated form of oxygen called singlet oxygen. The singlet oxygen is a cytotoxic agent and reacts rapidly with cellular components to cause damage that ultimately leads to cell death and tumor destruction. The changed topography of the film surface after deposition is caused by a local material transport and a material separation between formed particles (probably AgNO3) and an embedding polymer matrix as chitosan. This paper focuses on the current use of injectable in situ Au/(Ag)/chitosan hydrogels in cancer photodynamic treatment. Formulation protocols for their cytotoxic properties, their effect on cell growth in vitro and inhibition of tumor growth in vivo using mouse models, are discussed.

  12. Acceleration of polarized proton at the AGS

    SciTech Connect

    Lee, Y Y

    1980-01-01

    The unexpected importance of high energy spin effects and the success of the ZGS in correcting many intrinsic and imperfection depolarizing resonances led us to attempt to accelerate polarized protons in the AGS. A collaborative effort is underway by the groups in Argonne, Michigan, Rice, Yale and Brookhaven to improve and modify the AGS to accelerate polarized protons. With the appropriate funding the first polarized proton acceleration at the AGS should be possible by 1983.

  13. The cardiovascular response to the AGS

    NASA Technical Reports Server (NTRS)

    Cardus, David; Mctaggart, Wesley G.

    1993-01-01

    This paper reports the preliminary results of experiments on human subjects conducted to study the cardiovascular response to various g-levels and exposure times using an artificial gravity simulator (AGS). The AGS is a short arm centrifuge consisting of a turntable, a traction system, a platform and four beds. Data collection hardware is part of the communication system. The AGS provides a steep acceleration gradient in subjects in the supine position.

  14. AgI/Ag{sub 3}PO{sub 4} hybrids with highly efficient visible-light driven photocatalytic activity

    SciTech Connect

    Katsumata, Hideyuki; Hayashi, Takahiro; Taniguchi, Masanao; Suzuki, Tohru; Kaneco, Satoshi

    2015-03-15

    Highlights: • AgI/Ag{sub 3}PO{sub 4} hybrid was prepared via an in situ anion-exchange method. • AgI/Ag{sub 3}PO{sub 4} displays the excellent photocatalytic activity under visible light. • AgI/Ag{sub 3}PO{sub 4} readily transforms to be Ag@AgI/Ag{sub 3}PO{sub 4} system. • h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization over AgI/Ag{sub 3}PO{sub 4}. • The activity enhancement is ascribed to a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI. - Abstract: Highly efficient visible-light-driven AgI/Ag{sub 3}PO{sub 4} hybrid photocatalysts with different mole ratios of AgI were prepared via an in situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgI/Ag{sub 3}PO{sub 4} photocatalysts displayed the higher photocatalytic activity than pure Ag{sub 3}PO{sub 4} and AgI for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgI/Ag{sub 3}PO{sub 4} with 80% of AgI exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgI/Ag{sub 3}PO{sub 4} readily transformed to be Ag@AgI/Ag{sub 3}PO{sub 4} system while the photocatalytic activity of AgI/Ag{sub 3}PO{sub 4} remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgI/Ag{sub 3}PO{sub 4} hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI, in which Ag nanoparticles act as the charge separation center.

  15. Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method.

    PubMed

    Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

    2015-12-01

    Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor-Ag2S (0.9 eV) quantum dots (QDs)-in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields. PMID:26428017

  16. Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method

    NASA Astrophysics Data System (ADS)

    Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

    2015-10-01

    Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor—Ag2S (0.9 eV) quantum dots (QDs)—in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields.

  17. Photonic quantum technologies

    NASA Astrophysics Data System (ADS)

    O'Brien, Jeremy

    2013-03-01

    Of the approaches to quantum computing, photons are appealing for their low-noise properties and ease of manipulation, and relevance to other quantum technologies, including communication, metrology and measurement. We report an integrated waveguide approach to photonic quantum circuits for high performance, miniaturization and scalability [6-10]. We address the challenges of scaling up quantum circuits using new insights into how controlled operations can be efficiently realised, demonstrating Shor's algorithm with consecutive CNOT gates and the iterative phase estimation algorithm. We have shown how quantum circuits can be reconfigured, using thermo-optic phase shifters to realise a highly reconfigurable quantum circuit, and electro-optic phase shifters in lithium niobate to rapidly manipulate the path and polarisation of telecomm wavelength single photons. We have addressed miniaturisation using multimode interference architectures to directly implement NxN Hadamard operations, and by using high refractive index contrast materials such as SiOxNy, in which we have implemented quantum walks of correlated photons, and Si, in which we have demonstrated generation of orbital angular momentum states of light. We have incorporated microfluidic channels for the delivery of samples to measure the concentration of a blood protein with entangled states of light. We have begun to address the integration of superconducting single photon detectors and diamond and non-linear single photon sources. Finally, we give an overview of recent work on fundamental aspects of quantum measurement, including a quantum version of Wheeler's delayed choice experiment.

  18. Photonic Quantum Computing

    NASA Astrophysics Data System (ADS)

    Barz, Stefanie

    2013-05-01

    Quantum physics has revolutionized our understanding of information processing and enables computational speed-ups that are unattainable using classical computers. In this talk I will present a series of experiments in the field of photonic quantum computing. The first experiment is in the field of photonic state engineering and realizes the generation of heralded polarization-entangled photon pairs. It overcomes the limited applicability of photon-based schemes for quantum information processing tasks, which arises from the probabilistic nature of photon generation. The second experiment uses polarization-entangled photonic qubits to implement ``blind quantum computing,'' a new concept in quantum computing. Blind quantum computing enables a nearly-classical client to access the resources of a more computationally-powerful quantum server without divulging the content of the requested computation. Finally, the concept of blind quantum computing is applied to the field of verification. A new method is developed and experimentally demonstrated, which verifies the entangling capabilities of a quantum computer based on a blind Bell test.

  19. Virtual and real photons

    NASA Astrophysics Data System (ADS)

    Meulenberg, Andrew, Jr.

    2011-09-01

    Maxwell did not believe in photons. However, his equations lead to electro-magnetic field structures that are considered to be photonic by Quantum ElectroDynamics (QED). They are complete, relativistically correct, and unchallenged after nearly 150 years. However, even though his far-field solution has been considered as the basis for photons, as they stand and are interpreted, they are better fitted to the concept of virtual rather than to real photons. Comparison between staticcharge fields, near-field coupling, and photonic radiation will be made and the distinctions identified. The question of similarities in, and differences between, the two will be addressed. Implied assumptions in Feynman's "Lectures" could lead one to believe that he had provided a general classical electrodynamics proof that an orbital electron must radiate. While his derivation is correct, two of the conditions defined do not always apply in this case. As a result, the potential for misinterpretation of his proof (as he himself did earlier) for this particular case has some interesting implications. He did not make the distinction between radiation from a bound electron driven by an external alternating field and one falling in a nuclear potential. Similar failures lead to misinterpreting the differences between virtual and real photons.

  20. Optics Communications: Special issue on Polymer Photonics and Its Applications

    NASA Astrophysics Data System (ADS)

    Zhang, Ziyang; Pitwon, Richard C. A.; Feng, Jing

    2016-03-01

    In the last decade polymer photonics has witnessed a tremendous boost in research efforts and practical applications. Polymer materials can be engineered to exhibit unique optical and electrical properties. Extremely transparent and reliable passive optical polymers have been made commercially available and paved the ground for the development of various waveguide components. Advancement in the research activities regarding the synthesis of active polymers has enabled devices such as ultra-fast electro-optic modulators, efficient white light emitting diodes, broadband solar cells, flexible displays, and so on. The fabrication technology is not only fast and cost-effective, but also provides flexibility and broad compatibility with other semiconductor processing technologies. Reports show that polymers have been integrated in photonic platforms such as silicon-on-insulator (SOI), III-V semiconductors, and silica PLCs, and vice versa, photonic components made from a multitude of materials have been integrated, in a heterogeneous/hybrid manner, in polymer photonic platforms.