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1

Photochemical conversion of solar energy.  

PubMed

Energy is the most important issue of the 21st century. About 85% of our energy comes from fossil fuels, a finite resource unevenly distributed beneath the Earth's surface. Reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects such as pollution that threatens human health and greenhouse gases associated with global warming. Prompt global action to solve the energy crisis is therefore needed. To pursue such an action, we are urged to save energy and to use energy in more efficient ways, but we are also forced to find alternative energy sources, the most convenient of which is solar energy for several reasons. The sun continuously provides the Earth with a huge amount of energy, fairly distributed all over the world. Its enormous potential as a clean, abundant, and economical energy source, however, cannot be exploited unless it is converted into useful forms of energy. This Review starts with a brief description of the mechanism at the basis of the natural photosynthesis and, then, reports the results obtained so far in the field of photochemical conversion of solar energy. The "grand challenge" for chemists is to find a convenient means for artificial conversion of solar energy into fuels. If chemists succeed to create an artificial photosynthetic process, "... life and civilization will continue as long as the sun shines!", as the Italian scientist Giacomo Ciamician forecast almost one hundred years ago. PMID:18605661

Balzani, Vincenzo; Credi, Alberto; Venturi, Margherita

2008-01-01

2

ESR spectroscopy for monitoring the photochemical and thermal degradation of conjugated polymers used as electron donor materials in organic bulk heterojunction solar cells.  

PubMed

It was shown that ESR spectroscopy is a very useful technique for monitoring the photochemical and thermal degradation of conjugated polymers commonly used in organic solar cells. The relative stability of materials can be quantified by comparing the rates of trap accumulation (dCR/dt) estimated from their ESR profiles. PMID:25435101

Frolova, Lyubov A; Piven, Natalia P; Susarova, Diana K; Akkuratov, Alexander V; Babenko, Sergey D; Troshin, Pavel A

2015-01-27

3

19th International Conference on Photochemical Conversion and Storage of Solar Energy  

E-print Network

IPS-19 19th International Conference on Photochemical Conversion and Storage of Solar Energy 29@caltech.edu Prof. Harry Gray hbg@caltech.edu Prof. Jonas Peters jpeters@caltech.edu Dye-Sensitized & Polymer Solar Cells Advanced Photovoltaics Photocatalysis Solar Fuels Production Photoelectrochemistry

Goddard III, William A.

4

Organized assemblies of single wall carbon nanotubes and porphyrin for photochemical solar cells: charge injection from excited porphyrin into single-walled carbon nanotubes.  

PubMed

Photochemical solar cells have been constructed from organized assemblies of single-walled carbon nanotubes (SWCNT) and protonated porphyrin on nanostructured SnO2 electrodes. The protonated form of porphyrin (H4P2+) and SWCNT composites form 0.5-3.0 microm-sized rodlike structures and they can be assembled onto nanostructured SnO2 films [optically transparent electrode OTE/SnO2] by an electrophoretic deposition method. These organized assemblies are photoactive and absorb strongly in the entire visible region. The incident photon to photocurrent efficiency (IPCE) of OTE/SnO2/SWCNT-H4P2+ is approximately 13% at an applied potential of 0.2 V versus saturated calomel electrode. Femtosecond pump-probe spectroscopy experiments confirm the decay of the excited porphyrin in the SWCNT-H4P2+ assembly as it injects electrons into SWCNT. The dual role of SWCNT in promoting photoinduced charge separation and facilitating charge transport is presented. PMID:17165996

Hasobe, Taku; Fukuzumi, Shunichi; Kamat, Prashant V

2006-12-21

5

Photochemical solar cells based on d-band electrochemistry at transition metal diselenides. Technical progress report, second quarter, year one  

SciTech Connect

Single crystals of the layered semiconductor tungsten diselenide have been grown by chemical vapor transport and evaluated as the photoanode in a n-WSe/sub 2//1M KI-0.1mI/sub 2//Pt photoelectrochemical cell. Progress is detailed. In situ topographic photogenerated carrier collection analysis with a scanning laser spot technique has verified that crystal edges exposed to the electrolyte are a major source of efficiency losses in the light to electrical energy conversion. Surface states due to edge sites have been detected with subband gap photocurrent spectroscopy and found to be located 0.2 eV below the conduction band edge. Several approaches have been demonstrated for the specific chemical treatment of the edge sites to reduce the effect of the surface states and increase the energy conversion efficiency. It was also found that iodine reduction (dark current) via these surface states is another factor in limiting cell efficiency.

Parkinson, B.A.; Furtak, T.E.

1980-05-01

6

Photochemical conversion of solar energy in the environment. Book chapter  

SciTech Connect

Past research on photochemistry in the environment has focused on gas phase reactions in the atmosphere. Recently, however, environmentally significant photoreactions have been discovered in natural waters (i.e., the sea, lakes, and rivers), on soil surfaces, and in atmospheric condensed phases. These new investigations have been stimulated in part by interest in developing a scientific understanding of the role of photochemical processes in the biogeochemical cycles of various elements. In addition, other studies have explored the role of natural photochemical processes in cleansing the environemnt of various waste materials or, in some cases, in converting the wastes to more toxic substances. In the paper, current research results on the photochemical conversion of solar energy in aquatic environments and on soil and metal oxide surfaces are presented. Rate equations and products for selected homogeneous and heterogeneous photoreactions that occur in these systems are described. Data are presented for direct and sensitized photoreactions and for sunlight-initiated free radical reactions. (Copyright (c) 1991 Kluwer Academic Publishers.)

Zepp, R.G.

1991-01-01

7

Solar photochemical process engineering for production of fuels and chemicals  

NASA Technical Reports Server (NTRS)

The engineering costs and performance of a nominal 25,000 scmd (883,000 scfd) photochemical plant to produce dihydrogen from water were studied. Two systems were considered, one based on flat-plate collector/reactors and the other on linear parabolic troughs. Engineering subsystems were specified including the collector/reactor, support hardware, field transport piping, gas compression equipment, and balance-of-plant (BOP) items. Overall plant efficiencies of 10.3 and 11.6% are estimated for the flat-plate and trough systems, respectively, based on assumed solar photochemical efficiencies of 12.9 and 14.6%. Because of the opposing effects of concentration ratio and operating temperature on efficiency, it was concluded that reactor cooling would be necessary with the trough system. Both active and passive cooling methods were considered. Capital costs and energy costs, for both concentrating and non-concentrating systems, were determined and their sensitivity to efficiency and economic parameters were analyzed. The overall plant efficiency is the single most important factor in determining the cost of the fuel.

Biddle, J. R.; Peterson, D. B.; Fujita, T.

1984-01-01

8

Photochemical Studies of Chemistry in the Outer Solar System  

NASA Technical Reports Server (NTRS)

The goal of the proposed science investigation is to gain a quantitative understanding of chemical processes and their coupling with atmospheric dynamics in the reducing atmospheres of the outer solar system, with a particular focus on Infrared Space Observatory (ISO) observations and future experiments such as the Cassini Mission to Saturn and Titan. The proposed work is divided into two related tasks. We have carried out a systematic comparison between atmospheric models for every giant planet and Titan, which employ a consistent set of photochemical reactions. Combined with recent observations of hydrocarbon species by ISO, this can provide the most rigorous test of our current understanding of the photochemistry of hydrocarbon in the outer solar system. The emphasis will be on the methyl radical (CH3), first detected by IS0 in the atmospheres of Saturn and Neptune (Bezard et al. 1998). CH3 is one of the most important radicals in the hydrocarbon photochemistry because it is the primary product of methane photolysis and plays an essential role in forming C2H6, the most abundant and stable C2 species. A fundamental understanding of the distribution of CH3 provides unique insights into the chemistry of hydrocarbons as well as comparative planetology.

Yung, Yuk L.

2003-01-01

9

Solar Irradiation of Bilirubin: An Experiment in Photochemical Oxidation  

ERIC Educational Resources Information Center

An experiment in photochemical oxidation, which deals with bilirubin, a well-known light-sensitive biological compound that is pedagogically ideal for photochemical experiments at tertiary institutes, is presented. The experiment would benefit students in chemistry who eventually branch out into the health sciences or biochemistry.

Pillay A. E.; Salih, F. M.

2006-01-01

10

Solar Cells  

NASA Technical Reports Server (NTRS)

The Heat Exchanger Method (HEM) produces high efficiency crystal ingots in an automated well-insulated furnace offering low equipment, labor and energy costs. The "grown" silicon crystals are used to make solar cells, or photovoltaic cells which convert sunlight directly into electricity. The HEM method is used by Crystal Systems, Inc. and was developed under a NASA/Jet Propulsion Laboratory contract. The square wafers which are the result of the process are sold to companies manufacturing solar panels.

1983-01-01

11

The Impact of Aerosols on Solar Ultraviolet Radiation and Photochemical Smog  

Microsoft Academic Search

Photochemical smog, or ground-level ozone, has been the most recalcitrant of air pollution problems, but reductions in emissions of sulfur and hydrocarbons may yield unanticipated benefits in air quality. While sulfate and some organic aerosol particles scatter solar radiation back into space and can cool Earth`s surface, they also change the actinic flux of ultraviolet (UV) radiation. Observations and numerical

R. R. Dickerson; S. Kondragunta; G. Stenchikov; K. L. Civerolo; B. G. Doddridge; B. N. Holben

1997-01-01

12

The impact of aerosols on solar ultraviolet radiation an photochemical smog  

SciTech Connect

Photochemical smog, or ground-level ozone, has been the most recalcitrant of air pollution problems, but reductions in emissions of sulfur and hydrocarbons may yield unanticipated benefits in air quality. While sulfate and some organic aerosol particles scatter solar radiation back into space and can cool Earth`s surface, they also change the actinic flux of ultraviolet (UV) radiation. Observations and numerical models show that UV-scattering particles in the boundary layer accelerate photochemical reactions and smog production, but UV-absorbing aerosols such as mineral dust and soot inhibit smog production. Results could have major implications for the control of air pollution. 19 refs., 4 figs.

Dickerson, R.R.; Kondragunta, S.; Stenchikov, G. [Univ. of Maryland, College Park, MD (United States)] [and others] [Univ. of Maryland, College Park, MD (United States); and others

1997-10-31

13

Mars atmosphere loss and isotopic fractionation by solar-wind-induced sputtering and photochemical escape  

NASA Technical Reports Server (NTRS)

The effects of loss of Mars atmospheric constituents by solar-wind-induced sputtering and by photochemical escape during the last 3.8 b.y. were examined. Sputtering is capable of efficiently removing all species from the upper atmosphere, including the light noble gases; N also is removed by photochemical processes. Due to the diffusive separation by mass above the homopause, removal from the top of the atmosphere will fractionate the isotopes of each species, with the lighter mass being preferentially lost. For C and O, this allows us to determine the size of nonatmospheric reservoirs that mix with the atmosphere; these reserviors can be accounted for by exchange with CO2 adsorbed in the regolith and with H2O in the polar ice deposits. Both simple analytical models and time-dependent models of the loss of volatiles from and supply to the Martian atmosphere were constructed. Both Ar and Ne require continued replenishment from outgassing over geologic time.

Jakosky, B. M.; Pepin, R. O.; Johnson, R. E.; Fox, J. L.

1993-01-01

14

Supramolecular solar cells  

NASA Astrophysics Data System (ADS)

Supramolecular chemistry - chemistry of non-covalent bonds including different type of intermolecular interactions viz., ion-pairing, ion-dipole, dipole-dipole, hydrogen bonding, cation-pi and Van der Waals forces. Applications based on supramolecular concepts for developing catalysts, molecular wires, rectifiers, photochemical sensors have been evolved during recent years. Mimicking natural photosynthesis to build energy harvesting devices has become important for generating energy and solar fuels that could be stored for future use. In this dissertation, supramolecular chemistry is being explored for creating light energy harvesting devices. Photosensitization of semiconductor metal oxide nanoparticles, such as titanium dioxide (TiO2) and tin oxide (SnO2,), via host-guest binding approach has been explored. In the first part, self-assembly of different porphyrin macrocyclic compounds on TiO2 layer using axial coordination approach is explored. Supramolecular dye sensitized solar cells built based on this approach exhibited Incident Photon Conversion Efficiency (IPCE) of 36% for a porphyrin-ferrocene dyad. In the second part, surface modification of SnO2 with water soluble porphyrins and phthalocyanine resulted in successful self-assembly of dimers on SnO2 surface. IPCE more than 50% from 400 - 700 nm is achieved for the supramolecular self-assembled heterodimer photocells is achieved. In summary, the axial ligation and ion-pairing method used as supramolecular tools to build photocells, exhibited highest quantum efficiency of light energy conversion with panchromatic spectral coverage. The reported findings could be applied to create interacting molecular systems for next generation of efficient solar energy harvesting devices.

Subbaiyan, Navaneetha Krishnan

15

The three-dimensional photochemical model CHARM. Incorporation of solar activity  

NASA Astrophysics Data System (ADS)

We describe the numerical global photochemical model CHARM (CHemical Atmospheric Research Model) and the results of a numerical simulation of climatological distributions of ozone and other atmospheric trace gases in a height range of up to 90 km. We also present the results of numerical scenarios of an impact induced by a change in UV radiation fluxes in the solar activity cycle and conditioned by ozone depletion in polar regions by high-energy particles of cosmic origin. The spatial transport of chemically active species is described in the model (the Prather scheme) on the basis of global fields of wind components and temperature calculated by the ARM (Atmospheric Research Model) general circulation model.

Krivolutsky, A. A.; V'yushkova, T. Yu.; Cherepanova, L. A.; Kukoleva, A. A.; Repnev, A. I.; Banin, M. V.

2015-01-01

16

Heterojunction solar cell  

DOEpatents

A high-efficiency single heterojunction solar cell is described wherein a thin emitter layer (preferably Ga[sub 0.52]In[sub 0.48]P) forms a heterojunction with a GaAs absorber layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the emitter layer. 1 fig.

Olson, J.M.

1994-08-30

17

Using photochemical models for the validation of NO2 satellite measurements at different solar zenith angles  

NASA Astrophysics Data System (ADS)

SCIAMACHY (Scanning Imaging Spectrometer for Atmospheric Chartography) aboard the recently launched Environmental Satellite (ENVISAT) of ESA is measuring solar radiance upwelling from the atmosphere and the extraterrestrial irradiance. Appropriate inversion of the ultraviolet and visible radiance measurements, observed from the atmospheric limb, yields profiles of nitrogen dioxide, NO2, in the stratosphere. In order to assess their accuracy, the resulting NO2 profiles have been compared with those retrieved from the space borne occultation instruments Halogen Occultation Experiment (HALOE, data version v19) and Stratospheric Aerosol and Gas Experiment II (SAGE II, data version 6.20). As the HALOE and SAGE II measurements are performed during local sunrise or sunset and because NO2 has a significant diurnal variability, the NO2 profiles derived from HALOE and SAGE II have been transformed to those predicted for the solar zenith angles of the SCIAMACHY measurement by using a 1-D photochemical model. The model used to facilitate the comparison of the NO2 profiles from the different satellite sensors is described and an error assessment provided. Comparisons between NO2 profiles from SCIAMACHY and those from HALOE NO2 but transformed to the SCIAMACHY solar zenith angle, for collocations from July to October 2002, show good agreement (within +/-15%) between the altitude range from 22 to 33 km. The results from the comparison of all collocated NO2 profiles from SCIAMACHY and those from SAGE II transformed to the SCIAMACHY solar zenith angle show a systematic negative bias of 10 to 35% between 20 km to 38 km with a small standard deviation between 5 to 14%. These results agree with those of Newchurch and Ayoub (2004), implying that above 20 km NO2 profiles from SAGE II sunset are probably somewhat high.

Bracher, A.; Sinnhuber, M.; Rozanov, A.; Burrows, J. P.

2004-09-01

18

Fundamentals of solar cells  

Microsoft Academic Search

This text is addressed to upper level graduate students with background in solid state physics and to scientists and engineers involved in solar cell research. The author aims to present fundamental physical principles rather than the state-of-the-art. Specific devices are used to illustrate basic phenomena and to indicate possibilities for innovative design. Contents, abridged: Solar insolation. The calculation of solar

A. L. Farhenbruch; R. H. Bube

1983-01-01

19

Solar cells for solar power satellites  

Microsoft Academic Search

The concept of a solar-cell array for a solar power satellite is developed to permit evaluation of its economic feasibility for generating power for delivery to public utilities on earth. Gallium arsenide solar cells were considered but it could not be assured that the world gallium resources could support constructions of two solar power satellites per year. Therefore, for preliminary

H. Oman

1978-01-01

20

Solar cell shingle  

NASA Technical Reports Server (NTRS)

A solar cell shingle was made of an array of solar cells on a lower portion of a substantially rectangular shingle substrate made of fiberglass cloth or the like. The solar cells may be encapsulated in flourinated ethylene propylene or some other weatherproof translucent or transparent encapsulant to form a combined electrical module and a roof shingle. The interconnected solar cells were connected to connectors at the edge of the substrate through a connection to a common electrical bus or busses. An overlap area was arranged to receive the overlap of a cooperating similar shingle so that the cell portion of the cooperating shingle may overlie the overlap area of the roof shingle. Accordingly, the same shingle serves the double function of an ordinary roof shingle which may be applied in the usual way and an array of cooperating solar cells from which electrical energy may be collected.

Forestieri, A. F.; Ratajczak, A. F.; Sidorak, L. G. (inventors)

1977-01-01

21

Measuring solar-cell quality  

NASA Technical Reports Server (NTRS)

Automatic checking system illuminates solar cells to ensure minority carrier lifetime is at proper value. Testing method promises to make solar cell manufacture more economical, efficient and reliable.

Von Roos, O.

1977-01-01

22

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

Solar cell theory cells are manufactured, and how they are modeled mathematically is reviewed. The interaction of energetic charged particle radiation with solar cells is discussed in detail and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Finally, an extensive body of data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence is presented.

Tada, H. Y.; Carter, J. R., Jr.

1977-01-01

23

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

1982-01-01

24

Lateral superlattice solar cells  

SciTech Connect

A novel structure which comprises of a lateral superlattice as the active layer of a solar cell is proposed. If the alternating regions A and B of a lateral superlattice ABABAB... are chosen to have a Type-II band offset, it is shown that the performance of the active absorbing region of the solar cell is optimized. In essence, the Type-II lateral superlattice region can satisfy the material requirements for an ideal solar cells active absorbing region, i.e. simultaneously having a very high transition probability for photogeneration and a very long minority carrier recombination lifetime.

Mascarenhas, A.; Zhang, Y. [National Renewable Energy Lab., Golden, CO (United States); Millunchick, J.M.; Twesten, R.D.; Jones, E.D. [Sandia National Labs., Albuquerque, NM (United States)

1997-10-01

25

Solar cell array interconnects  

DOEpatents

Electrical interconnects for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value.

Carey, Paul G. (Mountain View, CA); Thompson, Jesse B. (Brentwood, CA); Colella, Nicolas J. (Livermore, CA); Williams, Kenneth A. (Livermore, CA)

1995-01-01

26

Solar cell array interconnects  

DOEpatents

Electrical interconnects are disclosed for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value. 4 figs.

Carey, P.G.; Thompson, J.B.; Colella, N.J.; Williams, K.A.

1995-11-14

27

Photovoltaic solar cell  

DOEpatents

A photovoltaic solar cell for generating electricity from sunlight is disclosed. The photovoltaic solar cell comprises a plurality of spaced-apart point contact junctions formed in a semiconductor body to receive the sunlight and generate the electricity therefrom, the plurality of spaced-apart point contact junctions having a first plurality of regions having a first doping type and a second plurality of regions having a second doping type. In addition, the photovoltaic solar cell comprises a first electrical contact electrically connected to each of the first plurality of regions and a second electrical contact electrically connected to each of the second plurality of regions, as well as a passivation layer covering major surfaces and sidewalls of the photovoltaic solar cell.

Nielson, Gregory N; Cruz-Campa, Jose Luis; Okandan, Murat; Resnick, Paul J

2014-05-20

28

Nanocrystal Solar Cells  

SciTech Connect

This dissertation presents the results of a research agenda aimed at improving integration and stability in nanocrystal-based solar cells through advances in active materials and device architectures. The introduction of 3-dimensional nanocrystals illustrates the potential for improving transport and percolation in hybrid solar cells and enables novel fabrication methods for optimizing integration in these systems. Fabricating cells by sequential deposition allows for solution-based assembly of hybrid composites with controlled and well-characterized dispersion and electrode contact. Hyperbranched nanocrystals emerge as a nearly ideal building block for hybrid cells, allowing the controlled morphologies targeted by templated approaches to be achieved in an easily fabricated solution-cast device. In addition to offering practical benefits to device processing, these approaches offer fundamental insight into the operation of hybrid solar cells, shedding light on key phenomena such as the roles of electrode-contact and percolation behavior in these cells. Finally, all-inorganic nanocrystal solar cells are presented as a wholly new cell concept, illustrating that donor-acceptor charge transfer and directed carrier diffusion can be utilized in a system with no organic components, and that nanocrystals may act as building blocks for efficient, stable, and low-cost thin-film solar cells.

Gur, Ilan

2006-12-15

29

Thin silicon solar cells  

SciTech Connect

The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M. [Astro Power Inc., Solar Park, Newark, DE (United States)

1992-12-01

30

Screening of solar cells  

NASA Technical Reports Server (NTRS)

Because solar cells in a production batch are not identical, screening is performed to obtain similar cells for aggregation into arrays. A common technique for screening is based on a single operating point of the I-V characteristic of the cell, usually the maximum power point. As a result, inferior cell matching may occur at the actual operating points. Screening solar cells based on the entire I-V characteristic will inherently result in more similar cells in the array. An array consisting of more similar cells is likely to have better overall characteristics and more predictable performance. Solar cell screening methods and cell ranking are discussed. The concept of a mean cell is defined as a cell 'best' representing all the cells in the production batch. The screening and ranking of all cells are performed with respect to the mean cell. The comparative results of different screening methods are illustrated on a batch of 50 silicon cells of the Space Station Freedom.

Appelbaum, J.; Chait, A.; Thompson, D. A.

1993-01-01

31

Welded solar cell interconnection  

NASA Technical Reports Server (NTRS)

The efficiency of the welding of solar-cell interconnects is compared with the efficiency of soldering such interconnects, and the cases in which welding may be superior are examined. Emphasis is placed on ultrasonic welding; attention is given to the solar-cell welding machine, the application of the welding process to different solar-cell configurations, producibility, and long-life performance of welded interconnects. Much of the present work has been directed toward providing increased confidence in the reliability of welding using conditions approximating those that would occur with large-scale array production. It is concluded that there is as yet insufficient data to determine which of three methods (soldering, parallel gap welding, and ultrasonic welding) provides the longest-duration solar panel life.

Stofel, E. J.; Browne, E. R.; Meese, R. A.; Vendura, G. J.

1982-01-01

32

Electron Transfer Dynamics in Efficient Molecular Solar Cells  

SciTech Connect

This research provided new mechanistic insights into surface mediated photochemical processes relevant to solar energy conversion. In this past three years our research has focused on oxidation photo-redox chemistry and on the role surface electric fields play on basic spectroscopic properties of molecular-semiconductor interfaces. Although this research as purely fundamental science, the results and their interpretation have relevance to applications in dye sensitized and photogalvanic solar cells as well as in the storage of solar energy in the form of chemical bonds.

Meyer, Gerald John

2014-10-01

33

Transparent solar cell module  

NASA Technical Reports Server (NTRS)

Modified solar cell module uses high transmission glass and adhesives, and heat dissipation to boost power per unit area by 25% (9.84% efficiency based on cell area at 60 C and 100 mW/sq cm flux). Design is suited for automatic production and is potentially more cost effective.

Antonides, G. J.; Dillard, P. A.; Fritz, W. M.; Lott, D. P.

1979-01-01

34

EE580 Solar Cells Todd J. Kaiser  

E-print Network

7/21/2010 1 EE580 ­ Solar Cells Todd J. Kaiser · Lecture 06 · Solar Cell Materials & Structures 1Montana State University: Solar Cells Lecture 6: Solar Cells Solar Cell Technologies · A) Crystalline Silicon · B) Thin Film · C) Group III-IV Cells 2Montana State University: Solar Cells Lecture 6: Solar

Kaiser, Todd J.

35

Broad spectrum solar cell  

DOEpatents

An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is In.sub.1-xGa.sub.xN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.

Walukiewicz, Wladyslaw (Kensington, CA); Yu, Kin Man (Lafayette, CA); Wu, Junqiao (Richmond, CA); Schaff, William J. (Ithaca, NY)

2007-05-15

36

Amorphous silicon solar cells  

Microsoft Academic Search

The photoconductive response of Schottky-barrier and p-i-n solar cell structures was analyzed. It shows that the photoconductivity determines the fill factor, rather than the dark current, as in crystalline silicon cells. An analysis of the I-V curves of p-i-n cells shows that the electron and hole drift lengths are comparable. High conductivity p and n type films (sigma = 1-10

D. E. Carlson; R. S. Crandall; J. Dresner; D. Goldstein; J. J. Hanak; A. R. Moore; R. E. Schade; D. L. Staebler; H. A. Weakliem; R. Williams

1981-01-01

37

Monolithic tandem solar cell  

SciTech Connect

It is an object of the invention to provide a monolithic tandem photovoltaic solar cell which is highly radiation resistant and efficient; in which the energy bandgap of the lower subcell can be tailored for specific applications; solar cell comprising layers of InP and GaInAsP (or GaInAs), where said photovoltaic cell is useful, for example, in space power applications; having an improved power-to-mass ratio; in which subcells are lattice-matches; and are both two terminal and three terminal monolithic tandem photovoltaic solar cells. To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the monolithic tandem photovoltaic solar cell may comprise; (a) an InP substrate having an upper surface; (b) a first photoactive subcell on the upper surface of the InP substrate; wherein the first subcell comprises GaInAs (which could include GaInAsP) and includes a homojunction; and (c) a second photoactive subcell on the first subcell; wherein the second subcell comprises InP and includes a homojunction. The cell is described in detail. 5 figs., 2 tabs.

Wanlass, M.W.

1989-11-03

38

Design, characterization and fabrication of silicon solar cells for ?50% efficient 6-junction tandem solar cells  

Microsoft Academic Search

A major objective for photovoltaic conversion is to develop high efficiency solar cells. Many approaches are under investigation - Multiple Junction Solar Cell, Multiple Spectrum Solar Cell, Multiple Absorption Path Solar Cell, Multiple Energy Solar Cell, and Multiple Temperature Solar Cells [1]. The Multiple Junction Solar Cell approach based on a six-junction tandem solar cell has been adopted to achieve

Ngwe Soe Zin; Andrew Blakers; Evan Franklin; Vernie Everett

2008-01-01

39

Monolithic tandem solar cell  

DOEpatents

A single-crystal, monolithic, tandem, photovoltaic solar cell is described which includes (a) an InP substrate having upper and lower surfaces, (b) a first photoactive subcell on the upper surface of the InP substrate, and (c) a second photoactive subcell on the first subcell. The first photoactive subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched. The solar cell can be provided as a two-terminal device or a three-terminal device.

Wanlass, Mark W. (Golden, CO)

1991-01-01

40

Monolithic tandem solar cell  

SciTech Connect

This patent describes a single-crystal, monolithic, tandem, photovoltaic solar cell which includes an InP substrate having an upper and lower surfaces, a first photoactive subcell on the upper surface of the InP substrate, and a second photoactive subcell on the first subcell. The first photovoltaic subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched. The solar cell can be provided as a two- terminal device or a three-terminal device.

Wanlass, M.W.

1991-05-28

41

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

A method is presented for predicting the degradation of a solar array in a space radiation environment. Solar cell technology which emphasizes the cell parameters that degrade in a radiation environment, is discussed along with the experimental techniques used in the evaluation of radiation effects. Other topics discussed include: theoretical aspects of radiation damage, methods for developing relative damage coefficients, nature of the space radiation environment, method of calculating equivalent fluence from electron and proton energy spectrums and relative damage coefficients, and comparison of flight data with estimated degradation.

Carter, J. R., Jr.; Tada, H. Y.

1973-01-01

42

Flexible Solar Cells  

NASA Technical Reports Server (NTRS)

Solar cell "modules" are plastic strips coated with thin films of photovoltaic silicon that collect solar energy for instant conversion into electricity. Lasers divide the thin film coating into smaller cells to build up voltage. Developed by Iowa Thin Film Technologies under NASA and DOE grants, the modules are used as electrical supply for advertising displays, battery rechargers for recreational vehicles, and to power model airplanes. The company is planning other applications both in consumer goods and as a power source in underdeveloped countries.

1994-01-01

43

Linking solar induced fluorescence and the photochemical reflectance index to carbon assimilation in a cornfield  

NASA Astrophysics Data System (ADS)

Determining the health and vigor of vegetation using high spectral resolution remote sensing techniques is a critical component in monitoring productivity from both natural and managed ecosystems and their feedbacks to climate. This presentation summarizes a field campaign conducted in a USDA-ARS experimental cornfield site located in Beltsville, MD, USA over a five-year period. The site is equipped with an instrumented tower which makes continuous eddy covariance measurements of CO2 along with incoming PAR. Hyperspectral reflectance observations were acquired over corn canopies with a USB4000 Miniature Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, Florida, USA) at multiple times a day at various stages through the growing season. On all field days, supporting plant information and leaf level data were acquired (e.g., CO2 gas exchange) as well as biophysical field data, including leaf area index (LAI), mid-day canopy PAR transmission, soil reflectivity, and soil moisture. The canopy optical measurements enabled retrievals of the photochemical reflectance index (PRI) and solar induced fluorescence (SIF) centered at O2-A and -B bands. These two spectrally based bio-indicators have been widely utilized in studies to assess whether vegetation is performing near-optimally or exhibiting symptoms of environmental stress (e.g., drought or nutrient deficiency, non-optimal temperatures, etc.). Both SIF and PRI expressed diurnal dynamics and seasonal changes that followed environmental conditions and physiological status of the cornfield. We further investigated the correlation between these two retrievals and the flux tower based carbon assimilation observations (i.e. gross ecosystem production, GEP). We were able to successfully model the variation of GEP (r2=0.81; RMSE=0.18 mg CO2/m2/s) by utilizing both SIF and PRI. Several cross-validation algorithms were applied to the model to demonstrate the robustness and consistency of the model. Our results suggest great potential of using SIF and PRI to monitor photosynthetic activities. Further studies are needed at various ecosystems.

Cheng, Y.; Middleton, E.; Zhang, Q.; Corp, L.; Campbell, P. K.; Huemmrich, K. F.; Kustas, W.; Daughtry, C. S.; Dulaney, W. P.; Russ, A.

2012-12-01

44

Solar cells for solar power satellites  

NASA Technical Reports Server (NTRS)

The concept of a solar-cell array for a solar power satellite is developed to permit evaluation of its economic feasibility for generating power for delivery to public utilities on earth. Gallium arsenide solar cells were considered but it could not be assured that the world gallium resources could support constructions of two solar power satellites per year. Therefore, for preliminary design an array blanket made from 5 by 10 cm silicon solar cells, 50 microns thick, and electrostatically bonded between borosilicate glass sheets was adopted. In annealing experiments, a radiated 50 microns thick cell was restored to its initial performance in a 500 C. Solar-cell efficiency effects significantly the solar power satellite mass, which varies from 90,000 metric tons for 20 percent cells to 120,000 metric tons for 12 percent cells. The anticipated cost of delivered power, based on 1977 dollars, varies from 4 cents per kWh with 18 percent cells, to 5 cents per kWh for 12 percent efficient cells.

Oman, H.

1978-01-01

45

Thin, Lightweight Solar Cell  

NASA Technical Reports Server (NTRS)

Improved design for thin, lightweight solar photovoltaic cells with front contacts reduces degradation of electrical output under exposure to energetic charged particles (protons and electrons). Increases ability of cells to maintain structural integrity under exposure to ultraviolet radiation by eliminating ultraviolet-degradable adhesives used to retain cover glasses. Interdigitated front contacts and front junctions formed on semiconductor substrate. Mating contacts formed on back surface of cover glass. Cover glass and substrate electrostatically bonded together.

Brandhorst, Henry W., Jr.; Weinberg, Irving

1991-01-01

46

Photochemical deposition of cobalt-based oxygen evolving catalyst on a semiconductor photoanode for solar oxygen production  

PubMed Central

This study describes the photochemical deposition of Co-based oxygen evolution catalysts on a semiconductor photoanode for use in solar oxygen evolution. In the photodeposition process, electron-hole pairs are generated in a semiconductor upon illumination and the photogenerated holes are used to oxidize Co2+ ions to Co3+ ions, resulting in the precipitation of Co3+-based catalysts on the semiconductor surface. Both photodeposition of the catalyst and solar O2 evolution are photo-oxidation reactions using the photogenerated holes. Therefore, photodeposition provides an efficient way to couple oxygen evolution catalysts with photoanodes by naturally placing catalysts at the locations where the holes are most readily available for solar O2 evolution. In this study Co-based catalysts were photochemically deposited as 1030 nm nanoparticles on the ZnO surface. The comparison of the photocurrent-voltage characteristics of the ZnO electrodes with and without the presence of the Co-based catalyst demonstrated that the catalyst generally enhanced the anodic photocurrent of the ZnO electrode with its effect more pronounced when the band bending is less significant. The presence of Co-based catalyst on the ZnO photoanode also shifted the onset potential of the photocurrent by 0.23 V to the negative direction, closer to the flat band potential. These results demonstrated that the cobalt-based catalyst can efficiently use the photogenerated holes in ZnO to enhance solar O2 evolution. The photodeposition method described in this study can be used as a general route to deposit the Co-based catalysts on any semiconductor electrode with a valence band edge located at a more positive potential than the oxidation potential of Co2+ ions. PMID:19934060

Steinmiller, Ellen M. P.; Choi, Kyoung-Shin

2009-01-01

47

Solar cell coverslide extraction apparatus  

Microsoft Academic Search

This patent describes an apparatus for extracting a coverslide from a solar cell in a solar cell module. The coverslide is adhered to the solar cell by a dissolvable layer of adhesive along a predetermined plane of attachment. The apparatus comprises: (a) a receptacle having a cavity defined therein; (b) a rack disposed in the cavity of the receptacle; (c)

1987-01-01

48

Solar-cell panel simulator  

Microsoft Academic Search

The energy generated by solar cells can be transformed into ac power by means of inverters. In most cases these inverters cannot be tested under real conditions, since large solar-cell arrays are not yet available at reasonable prices. Therefore, a circuit that simulates a solar-cell array has been developed.

D. Baert

1979-01-01

49

EE580 Solar Cells Todd J. Kaiser  

E-print Network

7/21/2010 1 EE580 ­ Solar Cells Todd J. Kaiser · Lecture 08 · Solar Cell Characterization 1Montana State University: Solar Cells Lecture 8: Characterization Solar Cell Operation n Emitter p Base Rear completing the circuit 2Montana State University: Solar Cells Lecture 8: Characterization Solar Cell

Kaiser, Todd J.

50

Very high efficiency solar cells  

NASA Astrophysics Data System (ADS)

The Defense Advanced Research Projects Agency has initiated the Very High Efficiency Solar Cell (VHESC) program to address the critical need of the soldier for power in the field. Very High Efficiency Solar Cells for portable applications that operate at greater than 55 percent efficiency in the laboratory and 50 percent in production are being developed. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space that leads to a new architecture paradigm. An integrated team effort is now underway that requires us to invent, develop and transfer to production these new solar cells. Our approach is driven by proven quantitative models for the solar cell design, the optical design and the integration of these designs. We start with a very high performance crystalline silicon solar cell platform. Examples will be presented. Initial solar cell device results are shown for devices fabricated in geometries designed for this VHESC Program.

Barnett, Allen; Kirkpatrick, Douglas; Honsberg, Christiana

2006-08-01

51

EDITORIAL: Nanostructured solar cells Nanostructured solar cells  

NASA Astrophysics Data System (ADS)

Conversion into electrical power of even a small fraction of the solar radiation incident on the Earth's surface has the potential to satisfy the world's energy demands without generating CO2 emissions. Current photovoltaic technology is not yet fulfilling this promise, largely due to the high cost of the electricity produced. Although the challenges of storage and distribution should not be underestimated, a major bottleneck lies in the photovoltaic devices themselves. Improving efficiency is part of the solution, but diminishing returns in that area mean that reducing the manufacturing cost is absolutely vital, whilst still retaining good efficiencies and device lifetimes. Solution-processible materials, e.g. organic molecules, conjugated polymers and semiconductor nanoparticles, offer new routes to the low-cost production of solar cells. The challenge here is that absorbing light in an organic material produces a coulombically bound exciton that requires dissociation at a donor-acceptor heterojunction. A thickness of at least 100 nm is required to absorb the incident light, but excitons only diffuse a few nanometres before decaying. The problem is therefore intrinsically at the nano-scale: we need composite devices with a large area of internal donor-acceptor interface, but where each carrier has a pathway to the respective electrode. Dye-sensitized and bulk heterojunction cells have nanostructures which approach this challenge in different ways, and leading research in this area is described in many of the articles in this special issue. This issue is not restricted to organic or dye-sensitized photovoltaics, since nanotechnology can also play an important role in devices based on more conventional inorganic materials. In these materials, the electronic properties can be controlled, tuned and in some cases completely changed by nanoscale confinement. Also, the techniques of nanoscience are the natural ones for investigating the localized states, particularly at surfaces and interfaces, which are often the limiting factor in device performance. This issue provides concrete examples of how the techniques of nanoscience and nanotechnology can be used to understand, control and optimize the performance of novel photovoltaic devices. We are grateful to the contributors for submitting high-quality papers around a common theme, even though they may not normally consider their work to fall under the banner of 'nanotechnology'. We would also like to thank the editorial and production staff at Nanotechnology for their efficient and speedy work in putting this issue together.

Greenham, Neil C.; Grtzel, Michael

2008-10-01

52

Quantum Dot Solar Cells  

NASA Astrophysics Data System (ADS)

We have been investigating the synthesis of quantum dots of CdSe, CuInS2, and CuInSe2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Bawendi, et. al., in the early 1990's. However, unlike previous work in this area we have also utilized single-source precursor molecules in the synthesis process. We will present XRD, TEM, SEM and EDS characterization of our initial attempts at fabricating these quantum dots. Investigation of the size distributions of these nanoparticles via laser light scattering and scanning electron microscopy will be presented. Theoretical estimates on appropriate quantum dot composition, size, and inter-dot spacing along with potential scenarios for solar cell fabrication will be discussed.

Raffaelle, Ryne P.; Castro, Stephanie L.; Hepp, Aloysius; Bailey, Sheila G.

2002-10-01

53

Quantum Dot Solar Cells  

NASA Technical Reports Server (NTRS)

We have been investigating the synthesis of quantum dots of CdSe, CuInS2, and CuInSe2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Bawendi, et. al., in the early 1990's. However, unlike previous work in this area we have also utilized single-source precursor molecules in the synthesis process. We will present XRD, TEM, SEM and EDS characterization of our initial attempts at fabricating these quantum dots. Investigation of the size distributions of these nanoparticles via laser light scattering and scanning electron microscopy will be presented. Theoretical estimates on appropriate quantum dot composition, size, and inter-dot spacing along with potential scenarios for solar cell fabrication will be discussed.

Raffaelle, Ryne P.; Castro, Stephanie L.; Hepp, Aloysius; Bailey, Sheila G.

2002-01-01

54

Superlattice cascade solar cell  

SciTech Connect

This paper reports progress toward realization of a new cascade solar cell structure whose chief advantages over other present concepts are: use of silicon for the substrate and low bandgap cell; avoidance of the necessity of lattice matching; and incorporation of a GaAs/GaP superlattice to enhance efficiency and provide a low-resistance connecting junction. Details of the design and operation of an OMCVD system for growing this structure are presented. Results of experiments to optimize layer thickness, compositional uniformity, and surface morphology are described.

Wanlass, M.W.; Blakeslee, A.E.

1982-09-01

55

Optical properties of tropospheric aerosols determined by lidar and spectrophotometric measurements (Photochemical Activity and Solar Ultraviolet Radiation campaign).  

PubMed

We present the results of the aerosol measurements carried out over the Aegean Sea during the Photochemical Activity and Solar Ultraviolet Radiation campaign held in Greece during June 1996. Simultaneous observations performed with a lidar and a double-monochromator spectrophotometer allowed us to retrieve the optical depth, the Angstrm coefficient, and the backscatter-to-extinction ratio. The Sun photometric data can be used to improve quantitative aerosol measurements by lidar in the Planetary Boundary Layer. Systematic errors could arise otherwise, because the value of the backscatter-to-extinction ratio has to be supplied. Instead this ratio can be retrieved experimentally by use of an iterative solution of the lidar equation. PMID:18259559

Marenco, F; Santacesaria, V; Bais, A F; Balis, D; di Sarra, A; Papayannis, A; Zerefos, C

1997-09-20

56

Solar cell module lamination process  

DOEpatents

A solar cell module lamination process using fluoropolymers to provide protection from adverse environmental conditions and thus enable more extended use of solar cells, particularly in space applications. A laminate of fluoropolymer material provides a hermetically sealed solar cell module structure that is flexible and very durable. The laminate is virtually chemically inert, highly transmissive in the visible spectrum, dimensionally stable at temperatures up to about 200.degree. C. highly abrasion resistant, and exhibits very little ultra-violet degradation.

Carey, Paul G. (Mountain View, CA); Thompson, Jesse B. (Brentwood, CA); Aceves, Randy C. (Tracy, CA)

2002-01-01

57

Monolithic tandem solar cell  

DOEpatents

A single-crystal, monolithic, tandem, photovoltaic solar cell is described which includes (a) an InP substrate having upper and lower surfaces, (b) a first photoactive subcell on the upper surface of the InP substrate, (c) a second photoactive subcell on the first subcell; and (d) an optically transparent prismatic cover layer over the second subcell. The first photoactive subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched. 9 figs.

Wanlass, M.W.

1994-06-21

58

Monolithic tandem solar cell  

SciTech Connect

A single-crystal, monolithic, tandem, photovoltaic solar cell is described which includes (a) an InP substrate having upper and lower surfaces, (b) a first photoactive subcell on the upper surface of the InP substrate, (c) a second photoactive subcell on the first subcell; and (d) an optically transparent prismatic cover layer over the second subcell. The first photoactive subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched.

Wanlass, Mark W. (Golden, CO)

1994-01-01

59

Solar Energy Materials & Solar Cells 91 (2007) 13881391 Bifacial configurations for CdTe solar cells  

E-print Network

Solar Energy Materials & Solar Cells 91 (2007) 1388­1391 Bifacial configurations for CdTe solar cells A. Romeob,?, G. Khrypunovc , S. Galassinid , H. Zogga , A.N. Tiwaria,e a Thin Film Physics Group We present a different back contact for CdTe solar cell by the application of only a transparent

Romeo, Alessandro

60

Solar Panel of Photovoltaic Cells  

USGS Multimedia Gallery

Solar panels or arrays of photovoltaic cells convert renewable solar radiation into electricity by a clean and environmentally sound means. Collected solar energy can either be used instantly or stored in batteries for later use. These systems can be used as a component of a larger photovoltaic syst...

61

Schottky barrier solar cell  

NASA Technical Reports Server (NTRS)

A method of fabricating a Schottky barrier solar cell is described. The cell consists of a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive. A thin layer of heavily doped n-type polycrystalling germanium is deposited on the substrate after a passivation layer is deposited to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes to serve as a base layer on which a thin layer of gallium arsenide is vapor-epitaxilly grown followed by a thermally-grown oxide layer. A metal layer is deposited on the oxide layer and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer.

Stirn, R. J.; Yeh, Y. C. M. (inventors)

1981-01-01

62

Using a photochemical model for the validation of NO2 satellite measurements at different solar zenith angles  

NASA Astrophysics Data System (ADS)

SCIAMACHY (Scanning Imaging Spectrometer for Atmospheric Chartography) aboard the recently launched Environmental Satellite (ENVISAT) of ESA is measuring solar radiance upwelling from the atmosphere and the extraterrestrial irradiance. Appropriate inversion of the ultraviolet and visible radiance measurements, observed from the atmospheric limb, yields profiles of nitrogen dioxide, NO2, in the stratosphere (SCIAMACHY-IUP NO2 profiles V1). In order to assess their accuracy, the resulting NO2 profiles have been compared with those retrieved from the space borne occultation instruments Halogen Occultation Experiment (HALOE, data version v19) and Stratospheric Aerosol and Gas Experiment II (SAGE II, data version 6.2). As the HALOE and SAGE II measurements are performed during local sunrise or sunset and because NO2 has a significant diurnal variability, the NO2 profiles derived from HALOE and SAGE II have been transformed to those predicted for the solar zenith angles of the SCIAMACHY measurement by using a 1-dimensional photochemical model. The model used to facilitate the comparison of the NO2 profiles from the different satellite sensors is described and a sensitivity ananlysis provided. Comparisons between NO2 profiles from SCIAMACHY and those from HALOE NO2 but transformed to the SCIAMACHY solar zenith angle, for collocations from July to October 2002, show good agreement (within +/-12%) between the altitude range from 22 to 33km. The results from the comparison of all collocated NO2 profiles from SCIAMACHY and those from SAGE II transformed to the SCIAMACHY solar zenith angle show a systematic negative bias of 10 to 35% between 20km to 38km with a small standard deviation between 5 to 14%. These results agree with those of Newchurch and Ayoub (2004), implying that above 20km NO2 profiles from SAGE II sunset are probably somewhat high.

Bracher, A.; Sinnhuber, M.; Rozanov, A.; Burrows, J. P.

2005-02-01

63

Lunar production of solar cells  

NASA Technical Reports Server (NTRS)

The feasibility of manufacturing of solar cells on the moon for spacecraft applications is examined. Because of the much lower escape velocity, there is a great advantage in lunar manufacture of solar cells compared to Earth manufacture. Silicon is abundant on the moon, and new refining methods allow it to be reduced and purified without extensive reliance on materials unavailable on the moon. Silicon and amorphous silicon solar cells could be manufactured on the moon for use in space. Concepts for the production of a baseline amorphous silicon cell are discussed, and specific power levels are calculated for cells designed for both lunar and Earth manufacture.

Landis, Geoffrey A.; Perino, Maria Antonietta

1989-01-01

64

Thin film solar cell workshop  

NASA Technical Reports Server (NTRS)

A summation of responses to questions posed to the thin-film solar cell workshop and the ensuing discussion is provided. Participants in the workshop included photovoltaic manufacturers (both thin film and crystalline), cell performance investigators, and consumers.

Armstrong, Joe; Jeffrey, Frank

1993-01-01

65

An Introduction to Solar Cells  

ERIC Educational Resources Information Center

Most likely, solar cells will play a significant role in this country's strategy to address the two interrelated issues of global warming and dependence on imported oil. The purpose of this paper is to present an explanation of how solar cells work at an introductory high school, college, or university physics course level. The treatment presented

Feldman, Bernard J.

2010-01-01

66

Stretchable polymer solar cell fibers.  

PubMed

Power yourself up: a sweater made from solar cells! Stretchable and wearable fibers are shown to be highly efficient polymer solar cells. Their stable energy conversion efficiency variation is below 10% even after 1000 bending cycles or stretching under a strain of 30%. These fibers can easily be woven into fabric from which any type of clothing can be made. PMID:25236579

Zhang, Zhitao; Yang, Zhibin; Deng, Jue; Zhang, Ye; Guan, Guozhen; Peng, Huisheng

2015-02-01

67

The challenges of organic polymer solar cells  

E-print Network

The technical and commercial prospects of polymer solar cells were evaluated. Polymer solar cells are an attractive approach to fabricate and deploy roll-to-roll processed solar cells that are reasonably efficient (total ...

Saif Addin, Burhan K. (Burhan Khalid)

2011-01-01

68

Upconversion in solar cells  

PubMed Central

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

2013-01-01

69

Germanium Nanocrystal Solar Cells  

NASA Astrophysics Data System (ADS)

Greenhouse gas concentrations in the atmosphere are approaching historically unprecedented levels from burning fossil fuels to meet the ever-increasing world energy demand. A rapid transition to clean energy sources is necessary to avoid the potentially catastrophic consequences of global warming. The sun provides more than enough energy to power the world, and solar cells that convert sunlight to electricity are commercially available. However, the high cost and low efficiency of current solar cells prevent their widespread implementation, and grid parity is not anticipated to be reached for at least 15 years without breakthrough technologies. Semiconductor nanocrystals (NCs) show promise for cheap multi-junction photovoltaic devices. To compete with photovoltaic materials that are currently commercially available, NCs need to be inexpensively cast into dense thin films with bulk-like electrical mobilities and absorption spectra that can be tuned by altering the NC size. The Group II-VI and IV-VI NC communities have had some success in achieving this goal by drying and then chemically treating colloidal particles, but the more abundant and less toxic Group IV NCs have proven more challenging. This thesis reports thin films of plasma-synthesized Ge NCs deposited using three different techniques, and preliminary solar cells based on these films. Germanium tetrachloride is dissociated in the presence of hydrogen in a nonthermal plasma to nucleate Ge NCs. Transmission electron microscopy and X-ray diffraction indicate that the particles are nearly monodisperse (standard deviations of 10-15% the mean particle diameter) and the mean diameter can be tuned from 4-15 nm by changing the residence time of the Ge NCs in the plasma. In the first deposition scheme, a Ge NC colloid is formed by reacting nanocrystalline powder with 1-dodecene and dispersing the functionalized NCs in a solvent. Films are then formed on substrates by drop-casting the colloid and allowing it to dry. As-deposited films are electrically insulating due to the long hydrocarbon molecules separating neighboring particles; however, mass spectrometry shows that annealing treatments successfully decompose these molecules. After annealing at 250 C, Ge NC films exhibit conductivities as large as 10-6 S/cm. In the second film deposition scheme, a Ge NC colloid is formed by dispersing Ge NCs in select solvents without further surface modification. While these "bare" NCs quickly agglomerate and flocculate in nearly all non-polar solvents, they remain stable in benzonitrile and 1,2-dichlorobenzene, among others. Thin-film field-effect transistors have been fabricated by spinning Ge NC colloids onto substrates and the films have been subjected to various annealing procedures. The devices show n-type, p -type, or ambipolar behavior depending on the annealing conditions, with Ge NC films annealed at 300C exhibiting electron saturation mobilities greater than 10-2 cm2/Vs and on-to-off ratios of 104. The final film deposition scheme involves the impaction of Ge NCs onto substrates downstream of the synthesis plasma via acceleration of the NCs through an orifice. This technique produces highly uniform films with densities greater than 50% of the density of bulk Ge. By varying the size of the Ge NCs, we have measured films with band gaps ranging from the bulk value of 0.7 eV to over 1.1 eV for films of 4 nm Ge NCs. Having deposited dense thin films with tunable band gaps and respectable mobilities, we have begun fabricating bilayer solar cells consisting of heterojunctions between Ge NC films and P3HT, Si NCs, or Si wafers. Preliminary devices exhibit opencircuit voltages and short-circuit currents as large as 0.3 V and 4 mA/cm 2, respectively.

Holman, Zachary Charles

70

Solar Energy Materials & Solar Cells 90 (2006) 664677 Invited article  

E-print Network

Solar Energy Materials & Solar Cells 90 (2006) 664­677 Invited article Recent developments in evaporated CdTe solar cells G. Khrypunova , A. Romeob , F. Kurdesauc , D.L. Ba¨ tznerd , H. Zogge , A Abstract Recent developments in the technology of high vacuum evaporated CdTe solar cells are reviewed

Romeo, Alessandro

71

Isomerization and Aggregation of the Solar Cell Dye D149  

PubMed Central

D149, a metal-free indoline dye, is one of the most promising sensitizers for dye-sensitized solar cells (DSSCs) and has shown very high solar energy conversion efficiencies of 9%. Effective electron injection from the excited state is a prerequisite for high efficiencies and is lowered by competing deactivation pathways. Previous investigations have shown surprisingly short-lived excited states for this dye, with maximum lifetime components of 100720 ps in different solvents and less than 120 ps for surface-adsorbed D149. Using steady-state and time-resolved fluorescence, we have investigated the photochemical properties of D149 in nonpolar and polar solvents, polymer matrices, and adsorbed on ZrO2, partially including a coadsorbent. In solution, excitation to the S2 state yields a product that is identified as a photoisomer. The reaction is reversible, and the involved double-bond is identified by NMR spectroscopy. Our results further show that lifetimes of 100330 ps in the solvents used are increased to more than 2 ns for D149 in polymer matrices and on ZrO2. This is in part attributed to blocked internal motion due to steric constraint. Conversely, concentration-dependent aggregation leads to a dramatic reduction in lifetimes that can affect solar cell performance. Our results explain the unexpectedly short lifetimes observed previously. We also show that photochemical properties such as lifetimes determined in solution are different from the ones determined on semiconductor surfaces used in solar cells. The obtained mechanistic understanding should help develop design strategies for further improvement of solar cell dyes. PMID:23378868

2012-01-01

72

Si Microwire Array Solar Cells  

SciTech Connect

Si microwire-array solar cells with Air Mass 1.5 Global conversion efficiencies of up to 7.9% have been fabricated using an active volume of Si equivalent to a 4 ?m thick Si wafer. These solar cells exhibited open-circuit voltages of 500 mV, short-circuit current densities (J{sub sc}) of up to 24 mA cm{sup -2}, and fill factors >65% and employed Al{sub 2}O{sub 3} dielectric particles that scattered light incident in the space between the wires, a Ag back reflector that prevented the escape of incident illumination from the back surface of the solar cell, and an a-SiN{sub x}:H passivation/anti-reflection layer. Wire-array solar cells without some or all of these design features were also fabricated to demonstrate the importance of the light-trapping elements in achieving a high J{sub sc}. Scanning photocurrent microscopy images of the microwire-array solar cells revealed that the higher J{sub sc} of the most advanced cell design resulted from an increased absorption of light incident in the space between the wires. Spectral response measurements further revealed that solar cells with light-trapping elements exhibited improved red and infrared response, as compared to solar cells without light-trapping elements.

Putnam, Morgan C.; Boettcher, Shannon W.; Kelzenberg, Michael D.; Turner-Evans, Daniel B.; Spurgeon, Joshua M.; Warren, Emily L.; Briggs, Ryan M.; Lewis, Nathan S.; Atwater, Harry A.

2010-01-01

73

Multiple Exciton Generation Solar Cells  

SciTech Connect

Heat loss is the major factor limiting traditional single junction solar cells to a theoretical efficiency of 32%. Multiple Exciton Generation (MEG) enables efficient use of the solar spectrum yielding a theoretical power conversion efficiency of 44% in solar cells under 1-sun conditions. Quantum-confined semiconductors have demonstrated the ability to generate multiple carriers but present-day materials deliver efficiencies far below the SQ limit of 32%. Semiconductor quantum dots of PbSe and PbS provide an active testbed for developing high-efficiency, inexpensive solar cells benefitting from quantum confinement effects. Here, we will present recent work of solar cells employing MEG to yield external quantum efficiencies exceeding 100%.

Luther, J. M.; Semonin, O. E.; Beard, M. C.; Gao, J.; Nozik, A. J.

2012-01-01

74

Solar electron source and thermionic solar cell  

NASA Astrophysics Data System (ADS)

Common solar technologies are either photovoltaic/thermophotovoltaic, or use indirect methods of electricity generation such as boiling water for a steam turbine. Thermionic energy conversion based on the emission of electrons from a hot cathode into vacuum and their collection by an anode is also a promising route. However, thermionic solar conversion is extremely challenging as the sunlight intensity is too low for heating a conventional cathode to thermionic emission temperatures in a practical manner. Therefore, compared to other technologies, little has been done in this area, and the devices have been mainly limited to large experimental apparatus investigated for space power applications. Based on a recently observed "Heat Trap" effect in carbon nanotube arrays, allowing their efficient heating with low-power light, we report the first compact thermionic solar cell. Even using a simple off-the-shelf focusing lens, the device delivered over 1 V across a load. The device also shows intrinsic storage capacity.

Yaghoobi, Parham; Vahdani Moghaddam, Mehran; Nojeh, Alireza

2012-12-01

75

Module level solutions to solar cell polarization  

SciTech Connect

A solar cell module includes interconnected solar cells, a transparent cover over the front sides of the solar cells, and a backsheet on the backsides of the solar cells. The solar cell module includes an electrical insulator between the transparent cover and the front sides of the solar cells. An encapsulant protectively packages the solar cells. To prevent polarization, the insulator has resistance suitable to prevent charge from leaking from the front sides of the solar cells to other portions of the solar cell module by way of the transparent cover. The insulator may be attached (e.g., by coating) directly on an underside of the transparent cover or be a separate layer formed between layers of the encapsulant. The solar cells may be back junction solar cells.

Xavier, Grace (Fremont, CA), Li; Bo (San Jose, CA)

2012-05-29

76

Integrating Solar Induced Fluorescence and the Photochemical Reflectance Index for Estimating Gross Primary Production in a Cornfield  

NASA Technical Reports Server (NTRS)

The utilization of remotely sensed observations for light use efficiency (LUE) and tower-based gross primary production (GPP) estimates was studied in a USDA cornfield. Nadir hyperspectral reflectance measurements were acquired at canopy level during a collaborative field campaign conducted in four growing seasons. The Photochemical Reflectance Index (PRI) and solar induced chlorophyll fluorescence (SIF), were derived. SIF retrievals were accomplished in the two telluric atmospheric oxygen absorption features centered at 688 nm (O2-B) and 760 nm (O2-A). The PRI and SIF were examined in conjunction with GPP and LUE determined by flux tower-based measurements. All of these fluxes, environmental variables, and the PRI and SIF exhibited diurnal as well as day-to-day dynamics across the four growing seasons. Consistent with previous studies, the PRI was shown to be related to LUE (r2 = 0.54 with a logarithm fit), but the relationship varied each year. By combining the PRI and SIF in a linear regression model, stronger performances for GPP estimation were obtained. The strongest relationship (r2 = 0.80, RMSE = 0.186 mg CO2/m2/s) was achieved when using the PRI and SIF retrievals at 688 nm. Cross-validation approaches were utilized to demonstrate the robustness and consistency of the performance. This study highlights a GPP retrieval method based entirely on hyperspectral remote sensing observations.

Cheng, Yen-Ben; Middleton, Elizabeth M.; Zhang, Qingyuan; Huemmrich, Karl F.; Campbell, Petya K. E.; Corp, Lawrence A.; Cook, Bruce D.; Kustas, William P.; Daughtry, Criag S.

2013-01-01

77

High intensity solar cell radiometer  

NASA Technical Reports Server (NTRS)

Device can be employed under high intensity illumination conditions such as would occur in a close-solar-approach space mission or in monitoring high intensity lamps. Radiometer consists of silicon solar cells with thin semi-transparent coatings of aluminum deposited on the front surfaces to permit transmission of small percentage of light and reflect the remainder.

Brandhorst, H. W.; Spisz, E. W.

1972-01-01

78

Solar Energy Materials & Solar Cells 91 (2007) 15991610 Improving solar cell efficiency using photonic band-gap materials  

E-print Network

Solar Energy Materials & Solar Cells 91 (2007) 1599­1610 Improving solar cell efficiency using efficiency of solar cell devices without using concentrators. r 2007 Elsevier B.V. All rights reserved) solar energy conversion systems (or solar cells) are the most widely used power systems. However

Dowling, Jonathan P.

79

Photochemical solar energy conversion utilizing semiconductors localized in membrane-mimetic systems  

SciTech Connect

Extending the frontiers of colloidal photochemistry and colloidal electrochemistry to solar photochemistry research had been the main objective of this research. More specific objectives of this proposal include the examination of semiconductor-particle-mediated photoelectron transfer and photoelectric effects in different membrane mimetic systems. Emphasis had been placed on developing bilayer lipid membranes and Langmuir-Blodgett films as new membrane-mimetic systems, as well as on the characterization and utilization of these systems.

Fendler, J.H.

1991-08-31

80

24% efficient silicon solar cells  

Microsoft Academic Search

This paper reports significant progress in silicon solar cell performance, taking confirmed efficiency beyond 24% for the first time. This progress has been achieved by a combination of several mechanisms. One is the reduction of recombination at the cell front surface by improved passivation of the silicon\\/silicon dioxide interface. Resistive losses in the cell have been reduced by a double-plating

Jianhua Zhao; Aihua Wang; Pietro P. Altermatt; Stuart R. Wenham; Marltin A. Green

1994-01-01

81

EE580 Solar Cells Todd J. Kaiser  

E-print Network

7/21/2010 1 EE580 ­ Solar Cells Todd J. Kaiser · Lecture 10 · Summary 1Montana State University: Solar Cells Lecture 10: Summary Summer 2010 Class Montana State University: Solar Cells Lecture 10: Summary 2 Solar Cell Operation n Emitter p Base Rear Contact Antireflection coating Absorption of photon

Kaiser, Todd J.

82

CCMR: Nanocrystal Sensitized Solar Cells  

NSDL National Science Digital Library

Nanocrystal sensitized solar cells demonstrate a possible cheap solution to practical device manufacture. This research examined the feasibility of using lead sulfide nanocrystals to sensitize tin dioxide and titanium dioxide substrates for the purpose of making a functioning photovoltaic device. Challenges included optimizing the substrate materials as well as the thin films made from them. Results indicate that titanium dioxide produces more suitable thin films than tin dioxide. Also, the methods employed did produce a functioning solar cell after optimization.

Perry, Alexis

2009-08-15

83

Dust removal from solar cells  

NASA Technical Reports Server (NTRS)

A solar panel cleaning device includes a solar panel having a plurality of photovoltaic cells arranged in rows and embedded in the solar panel with space between the rows. A transparent dielectric overlay is affixed to the solar panel. A plurality of electrode pairs each of which includes an upper and a lower electrode are arranged on opposite sides of the transparent dielectric and are affixed thereto. The electrodes may be transparent electrodes which may be arranged without concern for blocking sunlight to the solar panel. The solar panel may be a dielectric and its dielectric properties may be continuously and spatially variable. Alternatively the dielectric used may have dielectric segments which produce different electrical field and which affects the wind "generated."

Ashpis, David E. (Inventor)

2011-01-01

84

Enhanced Efficacy of Bleomycin in Bladder Cancer Cells by Photochemical Internalization  

PubMed Central

Bleomycin is a cytotoxic chemotherapeutic agent widely used in cancer treatment. However, its efficacy in different cancers is low, possibly due to limited cellular internalization. In this study, a novel approach known as photochemical internalization (PCI) was explored to enhance bleomycin delivery in bladder cancer cells (human T24 and rat AY-27), as bladder cancer is a potential indication for use of PCI with bleomycin. The PCI technique was mediated by the amphiphilic photosensitizer disulfonated tetraphenyl chlorin (TPCS2a) and blue light (435?nm). Two additional strategies were explored to further enhance the cytotoxicity of bleomycin; a novel peptide drug ATX-101 which is known to impair DNA damage responses, and the protease inhibitor E-64 which may reduce bleomycin degradation by inhibition of bleomycin hydrolase. Our results demonstrate that the PCI technique enhances the bleomycin effect under appropriate conditions, and importantly we show that PCI-bleomycin treatment leads to increased levels of DNA damage supporting that the observed effect is due to increased bleomycin uptake. Impairing the DNA damage responses by ATX-101 further enhances the efficacy of the PCI-bleomycin treatment, while inhibiting the bleomycin hydrolase does not. PMID:25101299

Hgset, Anders; Otterlei, Marit; Gederaas, Odrun A.

2014-01-01

85

Photochemical conversion of solar energy. Semiannual progress report 1 Jan30 Jun 1975  

Microsoft Academic Search

Totally-illuminated multi-thin-layer (TI-MTL) iron-thionine (Fe-TH+) photogalvanic cells have been constructed with SnO and InSnO, respectively, as transparent anode and cathode. A .07% sunlight engineering efficiency was achieved with a 4-element cell with 8l micrometer electrode separations. Single element TI-TL SnO\\/Pt Fe-TH+ cells have been sealed by enclosure and decline in output with time identified as due to leaching of tin

Lichtin

1975-01-01

86

Stable, high-efficiency amorphous silicon solar cells with low hydrogen content  

SciTech Connect

Results and conclusions obtained during a research program of the investigation of amorphous silicon and amorphous silicon based alloy materials and solar cells fabricated by photo-chemical vapor and glow discharge depositions are reported. Investigation of the effects of the hydrogen content in a-si:H i-layers in amorphous silicon solar cells show that cells with lowered hydrogen content i-layers are more stable. A classical thermodynamic formulation of the Staebler-Wronski effect has been developed for standard solar cell operating temperatures and illuminations. Methods have been developed to extract a lumped equivalent circuit from the current voltage characteristic of a single junction solar cell in order to predict its behavior in a multijunction device.

Fortmann, C.M.; Hegedus, S.S. (Institute of Energy Conversion, Newark, DE (United States))

1992-12-01

87

Natural variants of photosystem II subunit D1 tune photochemical fitness to solar intensity.  

PubMed

Photosystem II (PSII) is composed of six core polypeptides that make up the minimal unit capable of performing the primary photochemistry of light-driven charge separation and water oxidation in all oxygenic phototrophs. The D1 subunit of this complex contains most of the ligating amino acid residues for the Mn(4)CaO(5) core of the water-oxidizing complex (WOC). Most cyanobacteria have 3-5 copies of the psbA gene coding for at least two isoforms of D1, whereas algae and plants have only one isoform. Synechococcus elongatus PCC 7942 contains two D1 isoforms; D1:1 is expressed under low light conditions, and D1:2 is up-regulated in high light or stress conditions. Using a heterologous psbA expression system in the green alga Chlamydomonas reinhardtii, we have measured growth rate, WOC cycle efficiency, and O(2) yield as a function of D1:1, D1:2, or the native algal D1 isoform. D1:1-PSII cells outcompete D1:2-PSII cells and accumulate more biomass in light-limiting conditions. However, D1:2-PSII cells easily outcompete D1:1-PSII cells at high light intensities. The native C. reinhardtii-PSII WOC cycles less efficiently at all light intensities and produces less O(2) than either cyanobacterial D1 isoform. D1:2-PSII makes more O(2) per saturating flash than D1:1-PSII, but it exhibits lower WOC cycling efficiency at low light intensities due to a 40% faster charge recombination rate in the S(3) state. These functional advantages of D1:1-PSII and D1:2-PSII at low and high light regimes, respectively, can be explained by differences in predicted redox potentials of PSII electron acceptors that control kinetic performance. PMID:23271739

Vinyard, David J; Gimpel, Javier; Ananyev, Gennady M; Cornejo, Mario A; Golden, Susan S; Mayfield, Stephen P; Dismukes, G Charles

2013-02-22

88

Wraparound-contact solar cells  

NASA Technical Reports Server (NTRS)

Positive and negative electrical contacts are on back surface of wraparound-contact solar cell. With both terminals on nonilluminated side, cells can be connected back-to-back, and interconnection of many cells can be automated by using printed-circuit techniques. Cells are made by screen-printing layer of dielectric around edge of cell and extending top contact over dielectric to back surface. Wraparound also facilitates application of transparent covers and encapsulants. Efficiencies of cells are in excess of seventeen percent.

Baraona, C. R.; Klucher, T. M.; Thornhill, J. W.; Scott-Monck, J.

1979-01-01

89

Development of concentrator solar cells  

SciTech Connect

A limited pilot production run on PESC silicon solar cells for use at high concentrations (200 to 400 suns) is summarized. The front contact design of the cells was modified for operation without prismatic covers. The original objective of the contract was to systematically complete a process consolidation phase, in which all the, process improvements developed during the contract would be combined in a pilot production run. This pilot run was going to provide, a basis for estimating cell costs when produced at high throughput. Because of DOE funding limitations, the Photovoltaic Concentrator Initiative is on hold, and Applied Solar`s contract was operated at a low level of effort for most of 1993. The results obtained from the reduced scope pilot run showed the effects of discontinuous process optimization and characterization. However, the run provided valuable insight into the technical areas that can be optimized to achieve the original goals of the contract.

Not Available

1994-08-01

90

Performance of silicon solar cells under concentration  

Microsoft Academic Search

Generally solar cells have been designed and fabricated to work with unit solar flux. A cell optimized for such conditions definitely is not best for use under concentration. A theoretical model of a Si solar cell was developed to help with this optimization and then compared to experimental measurements made on commercial state-of-the-art cells at concentrations between 1 and 10

R. O. Bell; J. C. T. Ho; W. T. Kurth

1976-01-01

91

New mounting improves solar-cell efficiency  

NASA Technical Reports Server (NTRS)

Method boosts output by about 20 percent by trapping and redirecting solar radiation without increasing module depth. Mounted solar-cell array is covered with internally reflecting plate. Plate is attached to each cell by transparent adhesive, and space between cells is covered with layer of diffusely reflecting material. Solar energy falling on space between cells is diffused and reflected internally by plate until it is reflected onto solar cell.

Shepard, N. F., Jr.

1980-01-01

92

Evaluation of solar cell materials for a Solar Power Satellite  

NASA Technical Reports Server (NTRS)

Alternative solar cell materials being considered for the solar power satellite are described and price, production, and availability projections through the year 2000 are presented. The chief materials considered are silicon and gallium arsenide.

Glaser, P. E.; Almgren, D. W.; Csigi, K. I.

1980-01-01

93

Scanning Probe Microscopy of Organic Solar Cells  

NASA Astrophysics Data System (ADS)

Nanostructured composites of organic semiconductors are a promising class of materials for the manufacture of low-cost solar cells. Understanding how the nanoscale morphology of these materials affects their efficiency as solar energy harvesters is crucial to their eventual potential for large-scale deployment for primary power generation. In this thesis we describe the use of optoelectronic scanning-probe based microscopy methods to study this efficiency-structure relationship with nanoscale resolution. In particular, our objective is to make spatially resolved measurements of each step in the power conversion process from photons to an electric current, including charge generation, transport, and recombination processes, and correlate them with local device structure. We have achieved two aims in this work: first, to develop and apply novel electrically sensitive scanning probe microscopy experiments to study the optoelectronic materials and processes discussed above; and second, to deepen our understanding of the physics underpinning our experimental techniques. In the first case, we have applied conductive-, and photoconductive atomic force (cAFM & pcAFM) microscopy to measure both local photocurrent collection and dark charge transport properties in a variety of model and novel organic solar cell composites, including polymer/fullerene blends, and polymer-nanowire/fullerene blends, finding that local heterogeneity is the rule, and that improvements in the uniformity of specific beneficial nanostructures could lead to large increases in efficiency. We have used scanning Kelvin probe microscopy (SKPM) and time resolved-electrostatic force microscopy (trEFM) to characterize all-polymer blends, quantifying their sensitivity to photochemical degradation and the subsequent formation of local charge traps. We find that while trEFM provides a sensitive measure of local quantum efficiency, SKPM is generally unsuited to measurements of efficiency, less sensitive than trEFM, and of greater utility in identifying local changes in steady-state charge density that can be associated with charge trapping. In the second case, we have developed a new understanding of charge transport between a sharp AFM tip and planar substrates applicable to conductive and photoconductive atomic force microscopy, and shown that hole-only transport characteristics can be easily obtained including quantitative values of the charge carrier mobility. Finally, we have shown that intensity-dependent photoconductive atomic force microscopy measurements can be used to infer the 3D structure of organic photovoltaic materials, and gained new insight into the influence vertical composition of the these devices can have on their open-circuit voltage and its intensity dependence.

Reid, Obadiah G.

94

PHOTOCHEMICAL PRODUCTS IN URBAN MIXTURES ENHANCE INFLAMMATORY RESPONSES IN LUNG CELLS  

EPA Science Inventory

Complex urban air mixtures that realistically mimic urban smog can be generated for investigating adverse health effects. "Smog chambers" have been used for over 30 yr to conduct experiments for developing and testing photochemical models that predict ambient ozone (O(3)) concent...

95

Compensated amorphous silicon solar cell  

DOEpatents

An amorphous silicon solar cell incorporates a region of intrinsic hydrogenated amorphous silicon fabricated by a glow discharge wherein said intrinsic region is compensated by P-type dopants in an amount sufficient to reduce the space charge density of said region under illumination to about zero.

Carlson, David E. (Yardley, PA)

1980-01-01

96

Key Physical Mechanisms in Nanostructured Solar Cells  

SciTech Connect

The objective of the project was to study both theoretically and experimentally the excitation, recombination and transport properties required for nanostructured solar cells to deliver energy conversion efficiencies well in excess of conventional limits. These objectives were met by concentrating on three key areas, namely, investigation of physical mechanisms present in nanostructured solar cells, characterization of loss mechanisms in nanostructured solar cells and determining the properties required of nanostructured solar cells in order to achieve high efficiency and the design implications.

Dr Stephan Bremner

2010-07-21

97

EE580 Solar Cells Todd J. Kaiser  

E-print Network

7/21/2010 1 EE580 ­ Solar Cells Todd J. Kaiser · Lecture 05 · P-N Junction 1Montana State University: Solar Cells Lecture 5: P-N Junction P-N Junction · Solar Cell is a large area P-N junction electron (hole) positive) 2Montana State University: Solar Cells Lecture 5: P-N Junction p-n Junction p n P

Kaiser, Todd J.

98

EE580 Solar Cells Todd J. Kaiser  

E-print Network

7/21/2010 1 EE580 ­ Solar Cells Todd J. Kaiser · Lecture 02 Microfabrication ­ A combination · Photolithograpy · Depostion · Etching 1 Montana State University: Solar Cells Lecture 2: Microfabrication Flow Montana State University: Solar Cells Lecture 2: Microfabrication Questions · What is heat? · Heat

Kaiser, Todd J.

99

Very High Efficiency Solar Cell Modules  

Microsoft Academic Search

The Very High Efficiency Solar Cell (VHESC) program is developing integrated optical system - PV modules for portable applications that operate at greater than 50% efficiency. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space. Our approach is driven by proven quantitative models for the solar cell design, the optical design,

Allen Barnett; Douglas Kirkpatrick; Christiana Honsberg; Duncan Moore; Mark Wanlass; Keith Emery; Richard Schwartz; Dave Carlson; Stuart Bowden; Dan Aiken; Allen Gray; Sarah Kurtz; Larry Kazmerski; Myles Steiner; Jeffery Gray; Tom Davenport; Roger Buelow; Laszlo Takacs; Narkis Shatz; John Bortz; Omkar Jani; Keith Goossen; Fouad Kiamilev; Alan Doolittle; Ian Ferguson; Blair Unger; Greg Schmidt; Eric Christensen; David Salzman

2009-01-01

100

MILESTONES TOWARD 50% EFFICIENT SOLAR CELL MODULES  

Microsoft Academic Search

The Very High Efficiency Solar Cell (VHESC) program is developing integrated optical system - PV modules for portable applications that operate at greater than 50 percent efficiency. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space. Our approach is driven by proven quantitative models for the solar cell design, the optical

Allen Barnett; Douglas Kirkpatrick; Christiana Honsberg; Duncan Moore; Mark Wanlass; Keith Emery; Richard Schwartz; Dave Carlson; Stuart Bowden; Dan Aiken; Allen Gray; Sarah Kurtz; Larry Kazmerski; Tom Moriarty; Myles Steiner; Jeffery Gray; Tom Davenport; Roger Buelow; Laszlo Takacs; John Bortz; Omkar Jani; Keith Goossen; Fouad Kiamilev; Alan Doolittle; Ian Ferguson; Blair Unger; Greg Schmidt

101

EE580 Solar Cells Todd J. Kaiser  

E-print Network

7/21/2010 1 EE580 ­ Solar Cells Todd J. Kaiser · Lecture 09 · Photovoltaic Systems 1Montana State University: Solar Cells Lecture 9: PV Systems Several types of operating modes · Centralized power plant or wanted Montana State University: Solar Cells Lecture 9: PV Systems 2 Residential Side Mounted Montana

Kaiser, Todd J.

102

Photochemical bonding of epithelial cell-seeded collagen lattice to rat muscle layer for esophageal tissue engineering: a pilot study  

NASA Astrophysics Data System (ADS)

Bilayered tube structures consist of epithelial cell-seeded collagen lattice and muscle layer have been fabricated for esophageal tissue engineering. Good adhesion between layers in order to facilitate cell infiltration and neovascularization in the collagen lattice is required. Previous efforts include using other bioglues such as fibrin glue and silicone tube as the physical support. However, the former is subjected to chances of transmitting blood-born infectious disease and is time consuming while the latter requires a second surgical procedure. The current project aimed to bond the cell-seeded collagen lattice to muscle layer using photochemical bonding, which has previously been demonstrated a rapid and non-thermal procedure in bonding collagenous tissues. Rat esophageal epithelial cells were seeded on collagen lattice and together with the latissimus dorsi muscle layer, were exposed to a photosensitizer rose Bengal at the bonding surface. An argon laser was used to irradiate the approximated layers. Bonding strength was measured during the peeling test of the collagen layer from the muscle layer. Post-bonding cell viability was assessed using a modified NADH-diaphorase microassay. A pilot in vivo study was conducted by directly bonding the cell-seeded collagen layer onto the muscle flap in rats and the structures were characterized histologically. Photochemical bonding was found to significantly increase the adherence at the bonding interface without compromising the cell viability. This indicates the feasibility of using the technique to fabricate multi-layered structures in the presence of living cells. The pilot animal study demonstrated integration of the collagen lattice with the muscle layer at the bonding interface although the subsequent surgical manipulation disturbed the integration at some region. This means that an additional procedure removing the tube could be avoided if the approximation and thus the bonding are optimized. Cell infiltration and neovascularization were also evident demonstrating that direct bonding of engineered tissue structures in particular those with low processability such as collagen lattice to the host tissue is feasible.

Chan, Barbara P.; Sato, M.; Vacanti, Joseph P.; Kochevar, Irene E.; Redmond, Robert W.

2005-04-01

103

Nanostructured Materials for Solar Cells  

NASA Technical Reports Server (NTRS)

The use of both inorganic and organic nanostructured materials in producing high efficiency photovoltaics is discussed in this paper. Recent theoretical results indicate that dramatic improvements in device efficiency may be attainable through the use of semiconductor quantum dots in an ordinary p-i-n solar cell. In addition, it has also recently been demonstrated that quantum dots can also be used to improve conversion efficiencies in polymeric thin film solar cells. A similar improvement in these types of cells has also been observed by employing single wall carbon nanotubes. This relatively new carbon allotrope may assist both in the disassociation of excitons as well as carrier transport through the composite material. This paper reviews the efforts that are currently underway to produce and characterize these nanoscale materials and to exploit their unique properties.

Bailey, Sheila; Raffaelle, Ryne; Castro, Stephanie; Fahey, S.; Gennett, T.; Tin, P.

2003-01-01

104

Cascade Solar Cell Workshop report  

NASA Technical Reports Server (NTRS)

Issues related to the feasibility, research and development, and demonstration of a 30% AMO cascade solar cell discussed include the material selection, growth and fabrication techniques, and device development strategy for a monolithic (two terminal) cascade cell, a hybrid (four terminal) cascade cell, and a spectral splitting device (three cells). Workshop recommendations include: (1) initiate a long range research program to develop a three junction, monolithic, cascade cell using either AlGaAsSb-GaAsSb or AlGaInAs-GaInAs material system; (2) emphasize OM-CVD epitaxial growth technique, perhaps combined with other technologies in the near term to obtain tunnel junctions; (3) develop a two junction device first; (4) initiate a cascade solar cell modeling program to study and compare performance of two and four terminal cascade devices exposed to electron and proton irradiation; and (5) encourage and be open to new ideas for developing four terminal, hybrid, cascade cells exploiting novel component cell interconnect technologies.

Hutchby, J. A.

1980-01-01

105

Automated solar-cell-array assembly machine  

NASA Technical Reports Server (NTRS)

Continuous-feeding machine automatically bonds solar cells to printed-circuit substrate. In completed machine, cells move to test station where electrical characteristics could be checked. If performance of cell is below specifications, that cell is marked and removed. All machine functions are synchronized by electronics located within unit. It may help to lower costs in future solar-cell production.

Costogue, E. N.; Mueller, R. L.; Person, J. K.; Yasui, R. K.

1978-01-01

106

Mixed ternary heterojunction solar cell  

DOEpatents

A thin film heterojunction solar cell and a method of making it has a p-type layer of mixed ternary I-III-VI.sub.2 semiconductor material in contact with an n-type layer of mixed binary II-VI semiconductor material. The p-type semiconductor material includes a low resistivity copper-rich region adjacent the back metal contact of the cell and a composition gradient providing a minority carrier mirror that improves the photovoltaic performance of the cell. The p-type semiconductor material preferably is CuInGaSe.sub.2 or CuIn(SSe).sub.2.

Chen, Wen S. (Seattle, WA); Stewart, John M. (Seattle, WA)

1992-08-25

107

Point contact silicon solar cells  

NASA Technical Reports Server (NTRS)

The construction of a 22.2% efficient single-crystal silicon solar cell fabricated at Stanford University is described. The cell dimensions were 3 x 5 mm and 100 microns thick with a base lifetime of 500 microseconds. The cell featured light trapping between a texturized top surface and a reflective bottom surface, small point contact diffusions, alternating between n-type and p-type in a polka-dot pattern on the bottom surface, and a surface passivation on all surfaces between contact regions.

Swanson, R. M.

1986-01-01

108

Polymer surface micropatterning by plasma and VUV-photochemical modification for controlled cell culture  

Microsoft Academic Search

Surface chemical micropatterns have been created by both low-pressure cold plasma, and by vacuum ultraviolet (VUV) photochemical modification of biaxially oriented polypropylene (BOPP). Oxygen, nitrogen and ammonia plasma, and ammonia-VUV treatments have been performed, including through metal masks with micrometer-sized openings. Surface analysis by X-ray photoelectron spectroscopy (XPS) has been used to characterise the modified surfaces. Imaging time-of-flight secondary ion

Nial A. Bullett; Diane P. Bullett; Florina-Elena Truica-Marasescu; Sophie Lerouge; Fackson Mwale; Michael R. Wertheimer

2004-01-01

109

Towards stable silicon nanoarray hybrid solar cells  

PubMed Central

Silicon nanoarray hybrid solar cells benefit from the ease of fabrication and the cost-effectiveness of the hybrid structure, and represent a new research focus towards the utilization of solar energy. However, hybrid solar cells composed of both inorganic and organic components suffer from the notorious stability issue, which has to be tackled before the hybrid solar cells could become a viable alternative for harvesting solar energy. Here we show that Si nanoarray/PEDOT:PSS hybrid solar cells with improved stability can be fabricated via eliminating the water inclusion in the initial formation of the heterojunction between Si nanoarray and PEDOT:PSS. The Si nanoarray hybrid solar cells are stable against rapid degradation in the atmosphere environment for several months without encapsulation. This finding paves the way towards the real-world applications of Si nanoarray hybrid solar cells. PMID:24430057

He, W. W.; Wu, K. J.; Wang, K.; Shi, T. F.; Wu, L.; Li, S. X.; Teng, D. Y.; Ye, C. H.

2014-01-01

110

A flight experiment to determine GPS photochemical contamination accumulation rates  

NASA Technical Reports Server (NTRS)

It was recently suggested that photochemically deposited contamination, originating from volatiles outgassed by a spacecraft, may be responsible for the anomalous degradation in power seen on the GPS Block 1 vehicles. In an attempt to confirm, or deny, the photochemical deposition rates predicted, a study was undertaken to design a flight experiment to be incorporated on the GPS vehicles currently in production. The objective was to develop an inexpensive, light weight instrument package that would give information on the contamination levels within a few months of launch. Three types of apparatus were studied, Quartz Crystal Microbalances, (QCM's), modified solar cells, and calorimeters. A calorimeter was selected due primarily to its impact on the production schedule of the GPS vehicles. An analysis of the sensitivity of the final design is compared to the predicted contamination accumulation rates in order to determine how long after launch it will take the experiment to show the effects of photochemical contamination.

Tribble, A. C.; Haffner, J. W.

1990-01-01

111

Biological solar cell  

SciTech Connect

Recent reports have demonstrated the possibility of employing photoactive, biological membrane components in photoelectrochemical cells. Present studies in our laboratories have led to the attachment of a much simpler biological complex, the bacterial photosynthetic reaction center isolated from Rhodopseudomonas sphaeroides, directly onto a SnO/sub 2/ semiconductor electrode. Light-induced photovoltages (70mV) and photocurrents (0.5 ..mu..A/cm/sup 2/) not attributable to Dember effects have been observed in photoelectrochemical cells employing reaction-center-coated, SnO/sub 2/ working electrodes. Such reaction-center electrodes may serve as model systems for future organic photovoltaic devices.

Seibert, M.; Janzen, A.F.

1980-04-01

112

Solar Cell Simulation  

NSDL National Science Digital Library

In this activity, learners model the flow of energy from the sun as it enters a photovoltaic cell, moves along a wire and powers a load. The game-like atmosphere engages younger learners and helps them understand the continuous nature of the flow of energy. Note: to do this activity you need access to a large open area outside (e.g., a field or playground).

Susan Schleith

2007-01-01

113

Solar cells Improved Hybrid Solar Cells via in situ UV Polymerization  

E-print Network

Solar cells Improved Hybrid Solar Cells via in situ UV Polymerization Sanja Tepavcevic, Seth B-enhanced solar energy conversion. By using this simple in situ UV polymerization method that couples mobility of the photoactive layer can be enhanced. 1. Introduction Hybrid solar cells have been developed

Sibener, Steven

114

Study of solar cell welds  

NASA Technical Reports Server (NTRS)

The thermal imaging technique was evaluated for its capabilities in the nondestructive evaluation of solar cell welds. The temperature and spatial resolution of state of the art instrumentation was sufficient for both qualitative and quantitative determination of the quality of solar cell welds. The addition of color digitized thermography enhanced the aspects of the thermographic display and allowed easily computerized testing procedures. For automated testing systems an accurate correlation of weld quality with temperature profiles of the welds needs to be performed. In comparison, the holographic technique was complementary with the thermal imaging technique, except that the holographic analysis appeared to be more quantitative at the present time. However, the thermal imaging approach is much more versatile in overall capabilities.

Workman, G. L.

1978-01-01

115

Compensated amorphous silicon solar cell  

DOEpatents

An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon over said substrate and having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the electrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF.sub.3 doped intrinsic layer.

Devaud, Genevieve (629 S. Humphrey Ave., Oak Park, IL 60304)

1983-01-01

116

Dye-Sensitized Solar Cells  

NSDL National Science Digital Library

This lesson from The Lawrence Hall of Science was taught in spring 2012 and teaches students about nano and environmental technologies. Students will create "dye-sensitized solar cells (DSSC) using nano-crystalline titanium dioxide." This page includes links to the Source Articles for the Hands-on Module and Project Staff Write-ups of the Hands-on Module. Additionally, five documents provide lecture and lab materials for instructor use.

2014-06-03

117

Recent Advances in Solar Cell Technology  

NASA Technical Reports Server (NTRS)

The advances in solar cell efficiency, radiation tolerance, and cost over the last decade are reviewed. Potential performance of thin-film solar cells in space are discussed, and the cost and the historical trends in production capability of the photovoltaics industry are considered with respect to the requirements of space power systems. Concentrator cells with conversion efficiency over 30%, and nonconcentrating solar cells with efficiency over 25% are now available, and advanced radiation-tolerant cells and lightweight, thin-film arrays are both being developed. Nonsolar applications of solar cells, including thermophotovoltaics, alpha- and betavoltaics, and laser power receivers, are also discussed.

Landis, Geoffrey A.; Bailey, Sheila G.; Piszczor, Michael F., Jr.

1996-01-01

118

Spectral sensitization of nanocrystalline solar cells  

DOEpatents

This invention relates to dye sensitized polycrystalline photoelectrochemical solar cells for use in energy transduction from light to electricity. It concerns the utility of highly absorbing organic chromophores as sensitizers in such cells and the degree to which they may be utilized alone and in combination to produce an efficient photoelectrochemical cell, e.g., a regenerative solar cell.

Spitler, Mark T. (Concord, MA); Ehret, Anne (Malden, MA); Stuhl, Louis S. (Bedford, MA)

2002-01-01

119

Silicon Carbide Solar Cells Investigated  

NASA Technical Reports Server (NTRS)

The semiconductor silicon carbide (SiC) has long been known for its outstanding resistance to harsh environments (e.g., thermal stability, radiation resistance, and dielectric strength). However, the ability to produce device-quality material is severely limited by the inherent crystalline defects associated with this material and their associated electronic effects. Much progress has been made recently in the understanding and control of these defects and in the improved processing of this material. Because of this work, it may be possible to produce SiC-based solar cells for environments with high temperatures, light intensities, and radiation, such as those experienced by solar probes. Electronics and sensors based on SiC can operate in hostile environments where conventional silicon-based electronics (limited to 350 C) cannot function. Development of this material will enable large performance enhancements and size reductions for a wide variety of systems--such as high-frequency devices, high-power devices, microwave switching devices, and high-temperature electronics. These applications would supply more energy-efficient public electric power distribution and electric vehicles, more powerful microwave electronics for radar and communications, and better sensors and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines. The 6H-SiC polytype is a promising wide-bandgap (Eg = 3.0 eV) semiconductor for photovoltaic applications in harsh solar environments that involve high-temperature and high-radiation conditions. The advantages of this material for this application lie in its extremely large breakdown field strength, high thermal conductivity, good electron saturation drift velocity, and stable electrical performance at temperatures as high as 600 C. This behavior makes it an attractive photovoltaic solar cell material for devices that can operate within three solar radii of the Sun.

Bailey, Sheila G.; Raffaelle, Ryne P.

2001-01-01

120

A new filter that accurately mimics the solar UV-B spectrum using standard UV lamps: the photochemical properties, stabilization and use of the urate anion liquid filter.  

PubMed

The physiological effects unique to solar ultraviolet (UV)-B exposure (280-315 nm) are difficult to accurately replicate in the laboratory. This study evaluates the effectiveness of the sodium urate anion in a liquid filter that yields a spectrum nearly indistinguishable from the solar UV-B spectrum while filtering the emissions of widely used UV-B lamps. The photochemical properties and stability of this filter are examined and weighed against a typical spectrum of ground-level solar UV-B radiation. To test the effectiveness of this filter, light-saturated photosynthetic oxygen evolution rates were measured following exposure to UV-B filtered either by this urate filter or the widely used cellulose acetate (CA) filter. The ubiquitous marine Chlorophyte alga Dunaliella tertiolecta was tested under identical UV-B flux densities coupled with ecologically realistic fluxes of UV-A and visible radiation for 6 and 12 h exposures. These results indicate that the urate-filtered UV-B radiation yields minor photosynthetic inhibition when compared with exposures lacking in UV-B. This is in agreement with published experiments using solar radiation. In sharp contrast, radiation filtered by CA filters produced large inhibition of photosynthesis. PMID:20955223

Sampath-Wiley, Priya; Jahnke, Leland S

2011-02-01

121

The advanced solar cell orbital test  

NASA Technical Reports Server (NTRS)

The motivation for advanced solar cell flight experiments is discussed and the Advanced Solar Cell Orbital Test (ASCOT) flight experiment is described. Details of the types of solar cells included in the test and the kinds of data to be collected are given. The orbit will expose the cells to a sufficiently high radiation dose that useful degradation data will be obtained in the first year.

Marvin, D. C.; Gates, M.

1991-01-01

122

Solar cell preparation in thin silicon membranes  

Microsoft Academic Search

Solar cells prepared in a thin (≈30 ?m) crystalline silicon membrane with a supporting frame allow an evaluation of the potential of c-Si thin film cells on cheap substrates. At the same time, lightweight and more radiation-hard solar cells may have direct applications in space. This paper studies the fabrication process of solar cells in ≈30 ?m thick p-Si epitaxial

M. Libezny; J. Poortmans; M. Caymax; G. Beaucame; W. Laureys; J. Nijs

1997-01-01

123

Extended Temperature Solar Cell Technology Development  

NASA Technical Reports Server (NTRS)

Future NASA missions will require solar cells to operate both in regimes closer to the sun, and farther from the sun, where the operating temperatures will be higher and lower than standard operational conditions. NASA Glenn is engaged in testing solar cells under extended temperature ranges, developing theoretical models of cell operation as a function of temperature, and in developing technology for improving the performance of solar cells for both high and low temperature operation.

Landis, Geoffrey A.; Jenkins, Phillip; Scheiman, David; Rafaelle, Ryne

2004-01-01

124

heat treatment for solar cells  

NASA Astrophysics Data System (ADS)

CdTe is an important compound semiconductor for solar cells, and its use in nanowire-based heterostructures may become a critical requirement, owing to the potential scarcity of tellurium. The effects of the CdCl2 heat treatment are investigated on the physical properties of vertically aligned ZnO/CdTe core-shell nanowire arrays grown by combining chemical bath deposition with close space sublimation. It is found that recrystallization phenomena are induced by the CdCl2 heat treatment in the CdTe shell composed of nanograins: its crystallinity is improved while grain growth and texture randomization occur. The presence of a tellurium crystalline phase that may decorate grain boundaries is also revealed. The CdCl2 heat treatment further favors the chlorine doping of the CdTe shell with the formation of chlorine A-centers and can result in the passivation of grain boundaries. The absorption properties of ZnO/CdTe core-shell nanowire arrays are highly efficient, and more than 80% of the incident light can be absorbed in the spectral range of the solar irradiance. The resulting photovoltaic properties of solar cells made from ZnO/CdTe core-shell nanowire arrays covered with CuSCN/Au back-side contact are also improved after the CdCl2 heat treatment. However, recombination and trap phenomena are expected to operate, and the collection of the holes that are mainly photo-generated in the CdTe shell from the CuSCN/Au back-side contact is presumably identified as the main critical point in these solar cells.

Consonni, Vincent; Renet, Sbastien; Garnier, Jrme; Gergaud, Patrice; Arts, Lluis; Michallon, Jrme; Rapenne, Laetitia; Appert, Estelle; Kaminski-Cachopo, Anne

2014-05-01

125

Energy Conversion: Nano Solar Cell  

NASA Astrophysics Data System (ADS)

Problems of fossil-fuel-induced climate change have sparked a demand for sustainable energy supply for all sectors of economy. Most laboratories continue to search for new materials and new technique to generate clean energy at affordable cost. Nanotechnology can play a major role in solving the energy problem. The prospect for solar energy using Si-based technology is not encouraging. Si photovoltaics can produce electricity at 20-30 c//kWhr with about 25% efficiency. Nanoparticles have a strong capacity to absorb light and generate more electrons for current as discovered in the recent work of organic and dye-sensitized cell. Using cheap preparation technique such as screen-printing and self-assembly growth, organic cells shows a strong potential for commercialization. Thin Films research group at National University Malaysia has been actively involved in these areas, and in this seminar, we will present a review works on nanomaterials for solar cells and particularly on hybrid organic solar cell based on ZnO nanorod arrays. The organic layer consisting of poly[2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEHPPV) and [6, 6]-phenyl C61-butyric acid 3-ethylthiophene ester (PCBE) was spin-coated on ZnO nanorod arrays. ZnO nanorod arrays were grown on FTO glass substrates which were pre-coated with ZnO nanoparticles using a low temperature chemical solution method. A gold electrode was used as the top contact. The device gave a short circuit current density of 2.4910-4 mA/cm2 and an open circuit voltage of 0.45 V under illumination of a projector halogen light at 100 mW/cm2.

Yahaya, Muhammad; Yap, Chi Chin; Mat Salleh, Muhamad

2009-09-01

126

Integrally covered silicon solar cells.  

NASA Technical Reports Server (NTRS)

The electron-beam technique for evaporating dielectric materials onto solar cells has been examined and developed. Titanium oxide cell antireflection coatings have been obtained which compare to silicon monoxide in environmental capabilities and which provide 3 to 4% improvement over SiO for glass covered cells. Evaporation processes have been obtained which provide a 50 to 100 micromil thick transparent (0.5 to 1.0% absorption per mil), low stressed integral cover capable of surviving space type qualification testing. Irradiation with 10 to the 15th power 1-MeV electrons shows 2% darkening, and long term UV irradiation incurs approximately 1.3% cover darkening for 50 micromil thick covers.

Stella, P. M.; Somberg, H.

1972-01-01

127

Changes in photochemically significant solar UV spectral irradiance as estimated by the composite Mg II index and scale factors  

NASA Technical Reports Server (NTRS)

Quantitative assessment of the impact of solar ultraviolet irradiance variations on stratospheric ozone abundances currently requires the use of proxy indicators. The Mg II core-to-wing index has been developed as an indicator of solar UV activity between 175-400 nm that is independent of most instrument artifacts, and measures solar variability on both rotational and solar cycle time scales. Linear regression fits have been used to merge the individual Mg II index data sets from the Nimbus-7, NOAA-9, and NOAA-11 instruments onto a single reference scale. The change in 27-dayrunning average of the composite Mg II index from solar maximum to solar minimum is approximately 8 percent for solar cycle 21, and approximately 9 percent for solar cycle 22 through January 1992. Scaling factors based on the short-term variations in the Mg II index and solar irradiance data sets have been developed to estimate solar variability at mid-UV and near-UV wavelengths. Near 205 nm, where solar irradiance variations are important for stratospheric photo-chemistry and dynamics, the estimated change in irradiance during solar cycle 22 is approximately 10 percent using the composite Mg II index and scale factors.

Deland, Matthew T.; Cebula, Richard P.

1994-01-01

128

New experimental techniques for solar cells  

NASA Technical Reports Server (NTRS)

Solar cell capacitance has special importance for an array controlled by shunting. Experimental measurements of solar cell capacitance in the past have shown disagreements of orders of magnitude. Correct measurement technique depends on maintaining the excitation voltage less than the thermal voltage. Two different experimental methods are shown to match theory well, and two effective capacitances are defined for quantifying the effect of the solar cell capacitance on the shunting system.

Lenk, R.

1993-01-01

129

Solar Cell Modules With Improved Backskin  

DOEpatents

A laminated solar cell module comprises a front light transmitting support, a plurality of interconnected solar cells encapsulated by a light-transmitting encapsulant material, and an improved backskin formed of an ionomer/nylon alloy. The improved backskin has a toughness and melting point temperature sufficiently great to avoid any likelihood of it being pierced by any of the components that interconnect the solar cells.

Gonsiorawski, Ronald C. (Danvers, MA)

2003-12-09

130

Bypass diode for a solar cell  

DOEpatents

Bypass diodes for solar cells are described. In one embodiment, a bypass diode for a solar cell includes a substrate of the solar cell. A first conductive region is disposed above the substrate, the first conductive region of a first conductivity type. A second conductive region is disposed on the first conductive region, the second conductive region of a second conductivity type opposite the first conductivity type.

Rim, Seung Bum (Palo Alto, CA); Kim, Taeseok (San Jose, CA); Smith, David D. (Campbell, CA); Cousins, Peter J. (Menlo Park, CA)

2012-03-13

131

Improved monolithic tandem solar cell  

SciTech Connect

A single-crystal, monolithic, tandem, photovoltaic solar cell is described which includes (a) an InP substrate having upper and lower surfaces, (b) a first photoactive subcell on the upper surf ace of the InP substrate, (c) a second photoactive subcell on the first subcell; and (d) an optically transparent prismatic cover layer over the second subcell. The first photoactive subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched.

Wanlass, M.W.

1991-04-23

132

Very High Efficiency Solar Cell Modules  

SciTech Connect

The Very High Efficiency Solar Cell (VHESC) program is developing integrated optical system - PV modules for portable applications that operate at greater than 50% efficiency. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space. Our approach is driven by proven quantitative models for the solar cell design, the optical design, and the integration of these designs. Optical systems efficiency with an optical efficiency of 93% and solar cell device results under ideal dichroic splitting optics summing to 42.7 {+-} 2.5% are described.

Barnett, A.; Kirkpatrick, D.; Honsberg, C.; Moore, D.; Wanlass, M.; Emery, K.; Schwartz, R.; Carlson, D.; Bowden, S.; Aiken, D.; Gray, A.; Kurtz, S.; Kazmerski, L., et al

2009-01-01

133

Plasmonic antenna effects on photochemical reactions.  

PubMed

Efficient solar energy conversion has been vigorously pursued since the 1970s, but its large-scale implementation hinges on the availability of high-efficiency modules. For maximum efficiency, it is important to absorb most of the incoming radiation, which necessitates both efficient photoexcitation and minimal electron-hole recombination. To date, researchers have primarily focused on the latter difficulty: finding a strategy to effectively separate photoinduced electrons and holes. Very few reports have been devoted to broadband sunlight absorption and photoexcitation. However, the currently available photovoltaic cells, such as amorphous silicon, and even single-crystal silicon and sensitized solar cells, cannot respond to the wide range of the solar spectrum. The photoelectric conversion characteristics of solar cells generally decrease in the infrared wavelength range. Thus, the fraction of the solar spectrum absorbed is relatively poor. In addition, the large mismatch between the diffraction limit of light and the absorption cross-section makes the probability of interactions between photons and cell materials quite low, which greatly limits photoexcitation efficiency. Therefore, there is a pressing need for research aimed at finding conditions that lead to highly efficient photoexcitation over a wide spectrum of sunlight, particularly in the visible to near-infrared wavelengths. As characterized in the emerging field of plasmonics, metallic nanostructures are endowed with optical antenna effects. These plasmonic antenna effects provide a promising platform for artificially sidestepping the diffraction limit of light and strongly enhancing absorption cross-sections. Moreover, they can efficiently excite photochemical reactions between photons and molecules close to an optical antenna through the local field enhancement. This technology has the potential to induce highly efficient photoexcitation between photons and molecules over a wide spectrum of sunlight, from visible to near-infrared wavelengths. In this Account, we describe our recent work in using metallic nanostructures to assist photochemical reactions for augmenting photoexcitation efficiency. These studies investigate the optical antenna effects of coupled plasmonic gold nanoblocks, which were fabricated with electron-beam lithography and a lift-off technique to afford high resolution and nanometric accuracy. The two-photon photoluminescence of gold and the resulting nonlinear photopolymerization on gold nanoblocks substantiate the existence of enhanced optical field domains. Local two-photon photochemical reactions due to weak incoherent light sources were identified. The optical antenna effects support the unprecedented realization of (i) direct photocarrier injection from the gold nanorods into TiO(2) and (ii) efficient and stable photocurrent generation in the absence of electron donors from visible (450 nm) to near-infrared (1300 nm) wavelengths. PMID:21381706

Gao, Shuyan; Ueno, Kosei; Misawa, Hiroaki

2011-04-19

134

Monolithic and mechanical multijunction space solar cells  

NASA Technical Reports Server (NTRS)

High-efficiency, lightweight, radiation-resistant solar cells are essential to meet the large power requirements of future space missions. Single-junction cells are limited in efficiency. Higher cell efficiencies could be realized by developing multijunction, multibandgap solar cells. Monolithic and mechanically stacked tandem solar cells surpassing single-junction cell efficiencies have been fabricated. This article surveys the current status of monolithic and mechanically stacked multibandgap space solar cells, and outlines problems yet to be resolved. The monolithic and mechanically stacked cells each have their own problems related to size, processing, current and voltage matching, weight, and other factors. More information is needed on the effect of temperature and radiation on the cell performance. Proper reference cells and full-spectrum range simulators are also needed to measure efficiencies correctly. Cost issues are not addressed, since the two approaches are still in the developmental stage.

Jain, Raj K.; Flood, Dennis J.

1992-01-01

135

Low-temperature photo-activated inorganic electron transport layers for flexible inverted polymer solar cells  

NASA Astrophysics Data System (ADS)

A simple and versatile route of forming sol-gel-derived metal oxide n-type electron transport layers (ETLs) for flexible inverted polymer solar cells (PSCs) is proposed using low-temperature photochemical activation process. The photochemical activation, which is induced by deep ultraviolet irradiation on sol-gel films, allows formation of metal oxide n-type ETLs such as zinc oxide (ZnO) and indium gallium zinc oxide films at a low temperature. Compared to poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester inverted PSCs with thermally annealed ZnO ETLs (optimized efficiency of 3.26 0.03 %), the inverted PSCs with photo-activated ZnO ETLs showed an improved efficiency of 3.60 0.02 %. The enhanced photovoltaic property is attributed to efficient charge collection from low overall series resistance and high surface area-to-geometric area ratio by the photo-activated ZnO ETLs.

Lee, Jung-Wook; Lee, Soo-Hyoung; Kim, Yong-Hoon; Park, Sung Kyu

2014-09-01

136

A Surface-Controlled Solar Cell  

NASA Technical Reports Server (NTRS)

Open-circuit voltage and cell efficiency increased. Proposed technique for controlling recombination velocity on solar-cell surfaces provides cells of increased efficiency and open-circuit voltage. In present cells, uncontrolled surface recombination velocity degrades opencircuit voltage and efficiency. In cell using proposed technique, transparent conducting layer, insulated from cell contacts, biased to enable variable control of surface recombination velocity.

Daud, T.; Crotty, G. T.

1987-01-01

137

Front contact solar cell with formed emitter  

DOEpatents

A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

Cousins, Peter John (Menlo Park, CA)

2012-07-17

138

Front contact solar cell with formed emitter  

DOEpatents

A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

Cousins, Peter John

2014-11-04

139

Detailed balance theory of excitonic and bulk heterojunction solar cells  

Microsoft Academic Search

A generalized solar cell model for excitonic and classical bipolar solar cells describes the combined transport and interaction of electrons, holes, and excitons in accordance with the principle of detailed balance. Conventional inorganic solar cells, single-phase organic solar cells and bulk heterojunction solar cells, i.e., nanoscale mixtures of two organic materials, are special cases of this model. For high mobilities,

Thomas Kirchartz; Julian Mattheis; Uwe Rau

2008-01-01

140

Current and lattice matched tandem solar cell  

DOEpatents

A multijunction (cascade) tandem photovoltaic solar cell device is fabricated of a Ga.sub.x In.sub.1-x P (0.505.ltoreq.X.ltoreq.0.515) top cell semiconductor lattice matched to a GaAs bottom cell semiconductor at a low-resistance heterojunction, preferably a p+/n+ heterojunction between the cells. The top and bottom cells are both lattice matched and current matched for high efficiency solar radiation conversion to electrical energy.

Olson, Jerry M. (Lakewood, CO)

1987-01-01

141

The Case for the Large Scale Development of Solar Energy  

ERIC Educational Resources Information Center

Traces the history of solar energy development. Discusses global effects (temperature, particle and other pollution) of burning fossil fuels. Provides energy balance equations for solar energy distribution and discusses flat plate collectors, solar cells, photochemical and photobiological conversion of solar energy, heat pumps. (CS)

O'Reilly, S. A.

1977-01-01

142

Method for processing silicon solar cells  

DOEpatents

The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystallline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation.

Tsuo, Y. Simon (Golden, CO); Landry, Marc D. (Lafayette, CO); Pitts, John R. (Lakewood, CO)

1997-01-01

143

Method for processing silicon solar cells  

DOEpatents

The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystalline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation. 2 figs.

Tsuo, Y.S.; Landry, M.D.; Pitts, J.R.

1997-05-06

144

Preparation of heterojunction solar cell  

NASA Astrophysics Data System (ADS)

Heterojunction solar cells of SnO 2: P/ n-Si (textured), having AM1 efficiency of 11.0% on single silicon crystal, have been fabricated. The phosphorosu doped tin oxide films are deposited by chemical vapour deposition technique on a heated silicon substrate having a resistivity of 0.1 ? cm. Before the deposition of SnO 2: P, the wafers are textured and growth of a SiO 2 layer on the Si surface was avoided. The C- V measurement at 1 kHz frequency shows the abrupt nature of the junction with a built-in voltage Vd = 0.62 V. The variation of cell parameters with temperature has also been studied.

Vishwakarma, S. R.; Rahmatullah; Prasad, H. C.

1993-09-01

145

Solar power satellites - Heat engine or solar cells  

NASA Technical Reports Server (NTRS)

A solar power satellite is the energy-converting element of a system that can deliver some 10 GW of power to utilities on the earth's surface. We evaluated heat engines and solar cells for converting sunshine to electric power at the satellite. A potassium Rankine cycle was the best of the heat engines, and 50 microns thick single-crystal silicon cells were the best of the photovoltaic converters. Neither solar cells nor heat engines had a clear advantage when all factors were considered. The potassium-turbine power plant, however, was more difficult to assemble and required a more expensive orbital assembly base. We therefore based our cost analyses on solar-cell energy conversion, concluding that satellite-generated power could be delivered to utilities for around 4 to 5 cents a kWh.

Oman, H.; Gregory, D. L.

1978-01-01

146

Sensitized energy transfer for organic solar cells, optical solar concentrators, and solar pumped lasers  

E-print Network

The separation of chromophore absorption and excitonic processes, such as singlet exciton fission and photoluminescence, offers several advantages to the design of organic solar cells and luminescent solar concentrators ...

Reusswig, Philip David

2014-01-01

147

Solar cell degradation in proton radiation orbits  

NASA Technical Reports Server (NTRS)

Significant discrepancies have been observed between predicted and actual in-orbit silicon solar array degradation in orbits other than LEO (low Earth orbits) and GEO (geosynchronous orbit). These discrepancies have been diagnosed to arise probably from a combination of a lack of appropriate solar cell test data and from inadequacies in the models that relate the unidirectional and mono-energetic proton test data to the omnidirectional flux-energy spectra actually found in orbit. Relative damage coefficients and solar cell power outputs were discussed, and also were presented in graph form. Silicon and gallium arsenide solar cells were considered.

Rauschenbach, H. S.; Yaung, J. Y.

1984-01-01

148

Monolithic cascade-type solar cells  

NASA Technical Reports Server (NTRS)

Solar cells consist of a semiconductor base, a bottom cell with a band-gap energy of E1, and a top cell with a band-gap energy of E2, and 0.96 E1 1.36 eV and (0.80 E + 0.77) eV E2 (0.80 E1 + 0.92) eV. A monolithic cascade-type solar cell was prepared with an n(+)-type GaAs base, a GaInAs bottom solar cell, and a GaAiInAs top solar cell. The surface of the cell is coated with a SiO antireflection film. The efficiency of the cell is 32%.

Yamamoto, S.; Shibukawa, A.; Yamaguchi, M.

1985-01-01

149

Epitaxial silicon growth for solar cells  

NASA Technical Reports Server (NTRS)

Growth and fabrication procedures for the baseline solar cells are described along with measured cell parameters, and the results. Reproducibility of these results was established and the direction to be taken for higher efficiency is identified.

Daiello, R. V.; Robinson, P. H.; Richman, D.

1978-01-01

150

Double-sided solar cell package  

NASA Technical Reports Server (NTRS)

In a solar cell array of terrestrial use, an improved double-sided solar cell package, consisting of a photovoltaic cell having a metallized P-contact strip and an N-contact grid, provided on opposite faces of the cell, a transparent tubular body forming an enclosure for the cell. A pedestal supporting the cell from within the enclosure comprising an electrical conductor connected with the P-contact strip provided for each face of the cell, and a reflector having an elongated reflective surface disposed in substantially opposed relation with one face of the cell for redirecting light were also included.

Shelpuk, B. (inventor)

1979-01-01

151

Monolithic cells for solar fuels.  

PubMed

Hybrid energy generation models based on a variety of alternative energy supply technologies are considered the best way to cope with the depletion of fossil energy resources and to limit global warming. One of the currently missing technologies is the mimic of natural photosynthesis to convert carbon dioxide and water into chemical fuel using sunlight. This idea has been around for decades, but artificial photosynthesis of organic molecules is still far away from providing real-world solutions. The scientific challenge is to perform in an efficient way the multi-electron transfer reactions of water oxidation and carbon dioxide reduction using holes and single electrons generated in an illuminated semiconductor. In this tutorial review the design of photoelectrochemical (PEC) cells that combine solar water oxidation and CO2 reduction is discussed. In such PEC cells simultaneous transport and efficient use of light, electrons, protons and molecules has to be managed. It is explained how efficiency can be gained by compartmentalisation of the water oxidation and CO2 reduction processes by proton exchange membranes, and monolithic concepts of artificial leaves and solar membranes are presented. Besides transferring protons from the anode to the cathode compartment the membrane serves as a molecular barrier material to prevent cross-over of oxygen and fuel molecules. Innovative nano-organized multimaterials will be needed to realise practical artificial photosynthesis devices. This review provides an overview of synthesis techniques which could be used to realise monolithic multifunctional membrane-electrode assemblies, such as Layer-by-Layer (LbL) deposition, Atomic Layer Deposition (ALD), and porous silicon (porSi) engineering. Advances in modelling approaches, electrochemical techniques and in situ spectroscopies to characterise overall PEC cell performance are discussed. PMID:24526085

Rong, Jan; Bosserez, Tom; Martel, David; Nervi, Carlo; Boarino, Luca; Taulelle, Francis; Decher, Gero; Bordiga, Silvia; Martens, Johan A

2014-12-01

152

Efficient organic solar cells based on phthalocyanines  

Microsoft Academic Search

The primary goal of this thesis is to develop efficient organic solar cells by utilizing metallophthalocyanines (MPc) as donor materials. The role of centered metals in MPcs is discussed, and it is shown that a suitable choice of centered metals and device engineering lead to efficient MPc based solar cells. The effect of molecular packing of organic semiconductors on interfacial

Inho Kim

2010-01-01

153

50% Efficient Solar Cell Architectures and Designs  

Microsoft Academic Search

Very High Efficiency Solar Cells (VHESC) for portable applications [1] that operate at greater than 55 percent efficiency in the laboratory and 50 percent in production are being created. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space that leads to a new paradigm. This project requires us to invent, develop

Allen Barnett; Christiana Honsberg; Douglas Kirkpatrick; Sarah Kurtz; Duncan Moore; David Salzman; R. Schwartz; J. Gray; S. Bowden; K. Goossen; M. Haney; D. Aiken; M. Wanlass; K. Emery

2006-01-01

154

Epitaxial silicon growth for solar cells  

NASA Technical Reports Server (NTRS)

The epitaxial procedures, solar cell fabrication, and evaluation techniques are described. The development of baseline epitaxial solar cell structures grown on high quality conventional silicon substrates is discussed. Diagnostic layers and solar cells grown on four potentially low cost silicon substrates are considered. The crystallographic properties of such layers and the performance of epitaxially grown solar cells fabricated on these materials are described. An advanced epitaxial reactor, the rotary disc, is described along with the results of growing solar cell structures of the baseline type on low cost substrates. The add on cost for the epitaxial process is assessed and the economic advantages of the epitaxial process as they relate to silicon substrate selection are examined.

Daiello, R. V.; Robinson, P. H.; Richman, D.

1979-01-01

155

Nanowire-based All Oxide Solar Cells  

SciTech Connect

We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is enhanced with the addition of an intermediate oxide insulating layer between the nanowires and the nanoparticles. This observation of the important dependence of the shunt resistance on the photovoltaic performance is widely applicable to any nanowire solar cell constructed with the nanowire array in direct contact with one electrode.

Yang*, Benjamin D. Yuhas and Peidong; Yang, Peidong

2008-12-07

156

Coating Processes Boost Performance of Solar Cells  

NASA Technical Reports Server (NTRS)

NASA currently has spacecraft orbiting Mercury (MESSENGER), imaging the asteroid Vesta (Dawn), roaming the red plains of Mars (the Opportunity rover), and providing a laboratory for humans to advance scientific research in space (the International Space Station, or ISS). The heart of the technology that powers those missions and many others can be held in the palm of your hand - the solar cell. Solar, or photovoltaic (PV), cells are what make up the panels and arrays that draw on the Sun s light to generate electricity for everything from the Hubble Space Telescope s imaging equipment to the life support systems for the ISS. To enable NASA spacecraft to utilize the Sun s energy for exploring destinations as distant as Jupiter, the Agency has invested significant research into improving solar cell design and efficiency. Glenn Research Center has been a national leader in advancing PV technology. The Center s Photovoltaic and Power Technologies Branch has conducted numerous experiments aimed at developing lighter, more efficient solar cells that are less expensive to manufacture. Initiatives like the Forward Technology Solar Cell Experiments I and II in which PV cells developed by NASA and private industry were mounted outside the ISS have tested how various solar technologies perform in the harsh conditions of space. While NASA seeks to improve solar cells for space applications, the results are returning to Earth to benefit the solar energy industry.

2012-01-01

157

Silicon film solar cell process  

NASA Technical Reports Server (NTRS)

The most promising way to reduce the cost of silicon in solar cells while still maintaining performance is to utilize thin films (10 to 20 microns thick) of crystalline silicon. The method of solution growth is being employed to grow thin polycrystalline films of silicon on dissimilar substrates. The initial results indicate that, using tin as the solvent, this growth process only requires operating temperatures in the range of 800 C to 1000 C. Growth rates in the range of 0.4 to 2.0 microns per minute and grain sizes in the range of 20 to 100 microns were achieved on both quartz and coated steel substrates. Typically, an aspect ratio of two to three between the width and the Si grain thickness is seen. Uniform coverage of Si growth on quartz over a 2.5 x 2.5 cm area was observed.

Hall, R. B.; Mcneely, J. B.; Barnett, A. M.

1984-01-01

158

Heterojunction silicon microwire solar cells.  

PubMed

We report radial heterojunction solar cells of amorphous silicon on crystalline silicon microwires with high surface passivation. While the shortened collection path is exploited to increase the photocurrent, proper choice of the wire radius and the highly passivated surface prevent drastic decrease in the voltage due to high surface-to-volume ratio. The heterojunction is formed by depositing a ?12-16 nm of amorphous silicon on crystalline silicon wires of radius approximately equal to minority carrier diffusion length (?10 ?m). In spite of very short carrier lifetime (<1 ?s), the microwire array devices generate photocurrent of ?30 mA/cm(2), and the same time, voltages close to 600 mV are achieved, leading to efficiency in excess of 12% in extremely short carrier lifetime silicon. We also find that formation of nanocrystallites of silicon in the deposited film results in loss of the expected passivation. PMID:23170984

Gharghi, Majid; Fathi, Ehsanollah; Kante, Boubacar; Sivoththaman, Siva; Zhang, Xiang

2012-12-12

159

Tandem photovoltaic solar cells and increased solar energy conversion efficiency  

NASA Technical Reports Server (NTRS)

Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.

Loferski, J. J.

1976-01-01

160

Nanocomposite enables sensitized solar cell  

NASA Astrophysics Data System (ADS)

Dye Sensitized solar cells (DSSCs) are a promising candidate for next generation photovoltaic panels due to their low cost, easy fabrication process, and relative high efficiency. Despite considerable effort on the advancement of DSSCs, the efficiency has been stalled for nearly a decade due to the complex interplay among various DSSC components. DSSCs consist of a photoanode on a conducting substrate, infiltrated dye for light absorption and electron injection, and an electrolyte to regenerate the dye. On the photoanode is a high band-gap semiconducting material, primarily of a nanostructure morphology of titanium (II) dioxide (TiO2), dye molecules whose molar absorption is typically in the visible spectrum, are adsorbed onto the surface of TiO 2. To improve the current DSSCs, there are many parameters that can be investigated. In a conventional DSSC, a thick semiconducting layer such as the nanoparticle TiO2 layer induces charge separation efficiently while concurrently increasing the charge transport distance, leading the cell to suffer from more charge recombination and deterioration in charge collection efficiency. To improve on this limitation, TiO2 nanowires (NW) and nanotubes (NT) are explored to replace the nanoparticle photoanode. One-dimensional nanostructures are known for the excellent electron transport properties as well as maintaining a relatively high surface area. Hence one of the focuses of this thesis explores at using different morphologies and composition of TiO2 nanostructures to enhance electron collection efficiency. Another challenge in conventional DSSCs is the limit in light absorption of solar irradiation. Dyes are limited to absorption only in the visible range, and have a low molar absorption coefficient in the near infrared (NIR). Tuning dyes is extremely complicated and may have more disadvantages than simply by extending light harvesting. Therefore our strategy is to incorporate quantum dots to replace the dye, as well as prepare a cell for the possibility of co-sensitization, thereby extending the absorption of light in the visible and NIR. The first phase of the thesis involves the synthesis and characterization of the materials used for the cell. We successfully synthesized TiO2 nanowires and nanotubes and characterized them for the use as the photoanode. Both one-dimensional structures proved to have low resistivity, chemical stability, and high density. We also synthesized lead (II) sulfide (PbS) quantum dots (QDs) and explored at modifying their diameter in order to properly control their light harvesting potential into the NIR region. The electron transport kinetics proved to be faster in one-dimensional nanostructure due to their high crystallinity order and reduced elastic scattering of the electrons during transport. Furthermore, quantum dots were synthesized such that their band-gap allowed for the absorption of NIR light. This result extended the harvesting potential of our solar cell and suggests the possibility for co-sensitization in DSSCs using dye molecules and quantum dots. Hence, the focus of this thesis work is to systematically explore a transformative way to fundamentally enhance charge transport and extend light absorption by in the incorporation of two sensitizing agents.

Phuyal, Dibya D.

161

Semiconductor quantum dot-sensitized solar cells  

PubMed Central

Semiconductor quantum dots (QDs) have been drawing great attention recently as a material for solar energy conversion due to their versatile optical and electrical properties. The QD-sensitized solar cell (QDSC) is one of the burgeoning semiconductor QD solar cells that shows promising developments for the next generation of solar cells. This article focuses on recent developments in QDSCs, including 1) the effect of quantum confinement on QDSCs, 2) the multiple exciton generation (MEG) of QDs, 3) fabrication methods of QDs, and 4) nanocrystalline photoelectrodes for solar cells. We also make suggestions for future research on QDSCs. Although the efficiency of QDSCs is still low, we think there will be major breakthroughs in developing QDSCs in the future. PMID:24191178

Tian, Jianjun; Cao, Guozhong

2013-01-01

162

Integration of Solar Cells on Top of CMOS Chips Part I: aSi Solar Cells  

Microsoft Academic Search

We present the monolithic integration of deep- submicrometer complementary metal-oxide-semiconductor (CMOS) microchips with a-Si:H solar cells. Solar cells are manufactured directly on the CMOS chips. The microchips maintain comparable electronic performance, and the solar cells show efficiency values above 7%. The yield of photovoltaic cells on planarized CMOS chips is 92%. This integration allows integrated energy harvesting using established process

Jiwu Lu; Alexey Y. Kovalgin; Karine H. M. van der Werf; Ruud E. I. Schropp; Jurriaan Schmitz

2011-01-01

163

Development of gallium arsenide solar cells  

NASA Technical Reports Server (NTRS)

The potential of ion implantation as a means of developing gallium arsenide solar cells with high efficiency performance was investigated. Computer calculations on gallium arsenide cell characteristics are presented to show the effects of surface recombination, junction space-charge recombination, and built-in fields produced by nonuniform doping of the surface region. The fabrication technology is summarized. Electrical and optical measurements on samples of solar cells are included.

1973-01-01

164

Development of GaAs solar cells  

NASA Technical Reports Server (NTRS)

This is the second quarterly technical report on a program, the goal of which is to achieve high efficiency GaAs solar cells. Analysis was concerned with providing design information for use in experimentally determining optimum solar cell process parameters. The first quarterly report contained the results of those design calculations. Using those results as a guide, experimental work was initiated to determine optimum cell process parameters. The initial results on this phase of the program are reported.

Mcnally, P. J.

1972-01-01

165

LDEF solar cell radiation effects analysis  

NASA Technical Reports Server (NTRS)

Because of the extended time that the Long Duration Exposure Facility (LDEF) mission stayed in space, the solar cells on the satellite experienced greater environments than originally planned. The cells showed an overall degradation in performance that is due to the combined effects of the various space environments. The purpose of this analysis is to calculate the effect of the accumulated radiation on the solar cells, thereby helping Marshall Space Flight Center (MSFC) to unravel the relative power degradation from the different environments.

Rives, Carol J.; Azarewicz, Joseph L.; Massengill, Lloyd

1993-01-01

166

Solar elastosis in conjunctival squamous cell neoplasm.  

PubMed

Aim: To study the role of solar elastosis in the patient's with Conjunctival Squamous Cell Neoplasia (CSCN). Materials and Methods: Paraffin embedded 30 Conjunctival Squamous Cell Neoplasia tissues were studied for the presence of solar elastosis by Verhoeff's stain. Nineteen Squamous Cell Carcinoma (SCC), 6 Carcinoma In Situ (CIS) and 5 Conjunctival Intraepithelial Neoplasia (CIN) specimens were included in the study. Disease free conjunctiva and pterygium tissues were used as negative and positive control respectively. Results: Solar elastosis was found to be present in 19 of 30 (63.3%) Conjunctival Squamous Cell neoplasia specimens. Conclusion: Our study showed the presence of solar elastosis in conjunctival squamous cell neoplasia. Poor socioeconomic condition is an important factor as most of the elastosis positive patients were farmers. PMID:25494114

Deka, A C; Dutta, A M; Sarma, P C; Baruah, K C

2014-01-01

167

Solar cell preparation in thin silicon membranes  

SciTech Connect

Solar cells prepared in a thin ({approx} 30 {micro}m) crystalline silicon membrane with a supporting frame allow an evaluation of the potential of c-Si thin film cells on cheap substrates. In the same time, light-weight and more radiation-hard solar cells may have direct applications in space. This paper studies the fabrication process of solar cells in {approx} 30 {micro}m thick p-Si epitaxial layers, incorporating a p{sup +2}-Si etch-stop/back-surface field layer, using KOH etching. Wax, rubber and silicon nitride were tested as masking material during the etching. It was found that both wax and silicon nitride could be used as materials for masking of supporting frames for the solar cell thinning up to 30 {micro}m. However, silicon nitride does not reliably protect the frontside structure.

Libezny, M.; Poortmans, J.; Caymax, M.; Beaucarne, G.; Laureys, W.; Nijs, J. [IMEC, Leuven (Belgium)

1997-12-31

168

Heterojunction solar cell with passivated emitter surface  

DOEpatents

A high-efficiency heterojunction solar cell is described wherein a thin emitter layer (preferably Ga[sub 0.52]In[sub 0.48]P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer. 1 fig.

Olson, J.M.; Kurtz, S.R.

1994-05-31

169

Photothermal radiometer for concentrator solar cell measurements  

SciTech Connect

A photothermal technique for measuring the intensity of concentrated sunlight is described. In this technique chopped concentrated sunlight is allowed to impinge on a black metal plate, to produce a time-varying surface temperature, which is measured by an infrared radiometer followed by a lock-in amplifier. By calibrating this system with a solar cell in the range in which the cell short-circuit current is known to vary linearly with light intensity, high ratios of solar concentration can be determined. Using this technique, we found the short-circuit current of an n p solar cell to be linear with concentration up to 410 suns.

Birkeland, J.D.; Kaufman, I.; Backus, C.E.

1986-03-01

170

Bypass diode for a solar cell  

DOEpatents

Methods of fabricating bypass diodes for solar cells are described. In once embodiment, a method includes forming a first conductive region of a first conductivity type above a substrate of a solar cell. A second conductive region of a second conductivity type is formed on the first conductive region. In another embodiment, a method includes forming a first conductive region of a first conductivity type above a substrate of a solar cell. A second conductive region of a second conductivity type is formed within, and surrounded by, an uppermost portion of the first conductive region but is not formed in a lowermost portion of the first conductive region.

Rim, Seung Bum; Kim, Taeseok; Smith, David D; Cousins, Peter J

2013-11-12

171

Indium oxide/n-silicon heterojunction solar cells  

DOEpatents

A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

Feng, Tom (Morris Plains, NJ); Ghosh, Amal K. (New Providence, NJ)

1982-12-28

172

Materials refining for solar cell silicon  

NASA Astrophysics Data System (ADS)

Metallurgical refining processes for the production of solar cell silicon are described. The aim is to obtain an optimum purification effect with a minimum of process steps. The characterization of refined silicon is limited to chemical purity and its correlation with solar quality. Hydrometallurgical refining and pyrometallurgical refining (liquid-liquid extraction, liquid-gas extraction, and recrystallization in aluminum) are treated.

Dietl, J.

173

* Corresponding author. Solar Energy Materials & Solar Cells 58 (1999) 209}218  

E-print Network

* Corresponding author. Solar Energy Materials & Solar Cells 58 (1999) 209}218 A highly e$cient and stable CdTe/CdS thin "lm solar cell N. Romeo, A. Bosio, R. Tedeschi*, A. Romeo, V. Canevari Dipartimento$cient and stable CdTe/CdS thin "lm solar cells. Our cells are prepared in three subsequent phases. Firstly, we

Romeo, Alessandro

174

Towards high performance inverted polymer solar cells  

NASA Astrophysics Data System (ADS)

Bulk heterojunction polymer solar cells that can be fabricated by solution processing techniques are under intense investigation in both academic institutions and industrial companies because of their potential to enable mass production of flexible and cost-effective alternative to silicon-based electronics. Despite the envisioned advantages and recent technology advances, so far the performance of polymer solar cells is still inferior to inorganic counterparts in terms of the efficiency and stability. There are many factors limiting the performance of polymer solar cells. Among them, the optical and electronic properties of materials in the active layer, device architecture and elimination of PEDOT:PSS are the most determining factors in the overall performance of polymer solar cells. In this presentation, I will present how we approach high performance of polymer solar cells. For example, by developing novel materials, fabrication polymer photovoltaic cells with an inverted device structure and elimination of PEDOT:PSS, we were able to observe over 8.4% power conversion efficiency from inverted polymer solar cells.

Gong, Xiong

2013-03-01

175

Dye-sensitized solar cells  

DOEpatents

A low-cost dye-sensitized Schottky barrier solar cell is comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent. 3 figs.

Skotheim, T.A.

1980-03-04

176

Dye-sensitized solar cells  

DOEpatents

A low-cost dye-sensitized Schottky barrier solar cell comprised of a substrate of semiconductor with an ohmic contact on one face, a sensitizing dye adsorbed onto the opposite face of the semiconductor, a transparent thin-film layer of a reducing agent over the dye, and a thin-film layer of metal over the reducing agent. The ohmic contact and metal layer constitute electrodes for connection to an external circuit and one or the other or both are made transparent to permit light to penetrate to the dye and be absorbed therein for generating electric current. The semiconductor material chosen to be the substrate is one having a wide bandgap and which therefore is transparent; the dye selected is one having a ground state within the bandgap of the semiconductor to generate carriers in the semiconductor, and a first excited state above the conduction band edge of the semiconductor to readily conduct electrons from the dye to the semiconductor; the reducing agent selected is one having a ground state above the ground state of the sensitizer to provide a plentiful source of electrons to the dye during current generation and thereby enhance the generation; and the metal for the thin-film layer of metal is selected to have a Fermi level in the vicinity of or above the ground state of the reducing agent to thereby amply supply electrons to the reducing agent.

Skotheim, Terje A. [Berkeley, CA

1980-03-04

177

Heavily doped polysilicon-contact solar cells  

NASA Technical Reports Server (NTRS)

The first use of a (silicon)/heavily doped polysilicon)/(metal) structure to replace the conventional high-low junction or back-surface-field (BSF) structure of silicon solar cells is reported. Compared with BSF and back-ohmic-contact (BOC) control samples, the polysilicon-back solar cells show improvements in red spectral response (RSR) and open-circuit voltage. Measurement reveals that a decrease in effective surface recombination velocity S is responsible for this improvement. Decreased S results for n-type (Si:As) polysilicon, consistent with past findings for bipolar transistors, and for p-type (Si:B) polysilicon, reported here for the first time. Though the present polysilicon-back solar cells are far from optimal, the results suggest a new class of designs for high efficiency silicon solar cells. Detailed technical reasons are advanced to support this view.

Lindholm, F. A.; Neugroschel, A.; Arienzo, M.; Iles, P. A.

1985-01-01

178

Inexpensive silicon sheets for solar cells  

NASA Technical Reports Server (NTRS)

Technique of producing silicon sheets by drawing gridlike or porous graphite gauze through silicon melt is readily adaptable to mass production, making process applicable to inexpensive manufacture of solar cell arrays.

Ciszek, T. F.; Schwuttke, G. H.

1977-01-01

179

Solar cell array design handbook, volume 1  

NASA Technical Reports Server (NTRS)

Twelve chapters discuss the following: historical developments, the environment and its effects, solar cells, solar cell filters and covers, solar cell and other electrical interconnections, blocking and shunt diodes, substrates and deployment mechanisms, material properties, design synthesis and optimization, design analysis, procurement, production and cost aspects, evaluation and test, orbital performance, and illustrative design examples. A comprehensive index permits rapid locating of desired topics. The handbook consists of two volumes: Volume 1 is of an expository nature while Volume 2 contains detailed design data in an appendix-like fashion. Volume 2 includes solar cell performance data, applicable unit conversion factors and physical constants, and mechanical, electrical, thermal optical, magnetic, and outgassing material properties. Extensive references are provided.

Rauschenbach, H. S.

1976-01-01

180

Texturization of multicrystalline silicon solar cells  

E-print Network

A significant efficiency gain for crystalline silicon solar cells can be achieved by surface texturization. This research was directed at developing a low-cost, high-throughput and reliable texturing method that can create ...

Li, Dai-Yin

2010-01-01

181

Rational design of hybrid organic solar cells  

E-print Network

In this thesis, we will present a novel design for a nano-structured organic-inorganic hybrid photovoltaic material that will address current challenges in bulk heterojunction (BHJ) organic-based solar cell materials. ...

Lentz, Levi (Levi Carl)

2014-01-01

182

Double-walled carbon nanotube solar cells.  

PubMed

We directly configured double-walled carbon nanotubes as energy conversion materials to fabricate thin-film solar cells, with nanotubes serving as both photogeneration sites and a charge carriers collecting/transport layer. The solar cells consist of a semitransparent thin film of nanotubes conformally coated on a n-type crystalline silicon substrate to create high-density p-n heterojunctions between nanotubes and n-Si to favor charge separation and extract electrons (through n-Si) and holes (through nanotubes). Initial tests have shown a power conversion efficiency of >1%, proving that DWNTs-on-Si is a potentially suitable configuration for making solar cells. Our devices are distinct from previously reported organic solar cells based on blends of polymers and nanomaterials, where conjugate polymers generate excitons and nanotubes only serve as a transport path. PMID:17608444

Wei, Jinquan; Jia, Yi; Shu, Qinke; Gu, Zhiyi; Wang, Kunlin; Zhuang, Daming; Zhang, Gong; Wang, Zhicheng; Luo, Jianbin; Cao, Anyuan; Wu, Dehai

2007-08-01

183

Solar Cell Efficiency Tables (Version 39)  

SciTech Connect

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since July 2011 are reviewed.

Green, M. A.; Emery, K.; Hishikawa, Y.; Warta, W.; Dunlop, E. D.

2012-01-01

184

Monolithic solar cell panel of amorphous silicon  

Microsoft Academic Search

A monolithic solar cell panel has been fabricated using hydrogenated amorphous silicon (a-Si:H) as the semiconductor material. This device consists of a plate glass substrate bearing a number of long, narrow, parallel cells electrically connected in series along the lengths of the cells. It features several characteristics which make it uniquely attractive for large area devices (up to several sq

J. J. Hanak

1979-01-01

185

Terrestrial solar cells present and future  

Microsoft Academic Search

In this paper the principles of operation of various types of solar cell are described. Progress in photovoltaics is traced through the development of the monocrystalline silicon cell for space applications where the emphasis is upon reliability and power\\/weight ratio, to terrestrial cells where the emphasis is upon low-cost production. The role of other contenders such as polycrystalline silicon, amorphous

B. T. Debney; J. R. Knight

1978-01-01

186

Composite solar cell matrix is reliable, lightweight and flexible  

NASA Technical Reports Server (NTRS)

Conducting strips mechanically and electrically connect individual solar cells into a linear array of cells, called a solar submodule, and then connect in series two or more submodules to form a solar cell matrix. Tiny perforations in the strip make it easy to solder them directly to the individual solar cells.

Yasui, R. K.

1967-01-01

187

Catalysis of Photochemical Reactions.  

ERIC Educational Resources Information Center

Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

Albini, A.

1986-01-01

188

Photochemical solar energy conversion utilizing semiconductors localized in membrane-mimetic systems. Performance report, April 1, 1989--August 31, 1991  

SciTech Connect

Extending the frontiers of colloidal photochemistry and colloidal electrochemistry to solar photochemistry research had been the main objective of this research. More specific objectives of this proposal include the examination of semiconductor-particle-mediated photoelectron transfer and photoelectric effects in different membrane mimetic systems. Emphasis had been placed on developing bilayer lipid membranes and Langmuir-Blodgett films as new membrane-mimetic systems, as well as on the characterization and utilization of these systems.

Fendler, J.H.

1991-08-31

189

Nanowire dye-sensitized solar cells  

Microsoft Academic Search

Excitonic solar cells-including organic, hybrid organic-inorganic and dye-sensitized cells (DSCs)-are promising devices for inexpensive, large-scale solar energy conversion. The DSC is currently the most efficient and stable excitonic photocell. Central to this device is a thick nanoparticle film that provides a large surface area for the adsorption of light-harvesting molecules. However, nanoparticle DSCs rely on trap-limited diffusion for electron transport,

Matt Law; Lori E. Greene; Justin C. Johnson; Richard Saykally; Peidong Yang

2005-01-01

190

Stretchable, wearable dye-sensitized solar cells.  

PubMed

A stretchable, wearable dye-sensitized solar-cell textile is developed from elastic, electrically conducting fiber as a counter electrode and spring-like titanium wire as the working electrode. Dyesensitized solar cells are demonstrated with energy-conversion efficiencies up to 7.13%. The high energy-conversion efficiencies can be well maintained under stretch by 30% and after stretch for 20 cycles. PMID:24648169

Yang, Zhibin; Deng, Jue; Sun, Xuemei; Li, Houpu; Peng, Huisheng

2014-05-01

191

High-temperature Solar Cell Development  

NASA Technical Reports Server (NTRS)

The vast majority of space probes to date have relied upon photovoltaic power generation. If future missions designed to probe environments close to the sun (Figure 1) will be able to use such power generation, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. The significant problem is that solar cells lose performance at high temperatures.

Landis, Geoffrey A.; Merritt, Danielle; Raffaelle, Ryne P.; Scheiman, David

2005-01-01

192

Fabrication of nanostructured CIGS solar cells  

NASA Astrophysics Data System (ADS)

We present the work on Cu(In,Ga)(Se,S)2 based nanostructured solar cells based on nanowire arrays. CIGS as the light absorber for thin-film solar cells has been widely studied recently, due to its high absorption coefficient, long-term stability, and low-cost of fabrication. Recently, solution phase processed CIGS thin film solar cells attracted great attention due to their extremely low fabrication cost. However, the performance is lower than vacuum based thin films possibly due to higher density of defects and lower carrier mobility. On the other hand, one dimensional ordered nanostructures such as nanowires and nanorods can be used to make redial junction solar cells, where the orthogonality between light absorption and charge carrier separation can lead to enhanced PV performance. Since the charge carriers only need to traverse a short distance in the radial direction before they are separated at the heterojunction interface, the radial junction scheme can be more defect tolerant than their planar junction scheme. In this work, a wide band gap nanowire or nanotube array such as TiO2 is used as a scaffold where CIGS is conformally coated using solution phase to obtain a radial heterojunction solar cell. Their performance is compared that of the planar thin film solar cells fabricated with the same materials.

Zhang, Hongwang; Wang, Fang; Parry, James; Perera, Samanthe; Zeng, Hao

2012-02-01

193

Perovskite solar cells: from materials to devices.  

PubMed

Perovskite solar cells based on organometal halide light absorbers have been considered a promising photovoltaic technology due to their superb power conversion efficiency (PCE) along with very low material costs. Since the first report on a long-term durable solid-state perovskite solar cell with a PCE of 9.7% in 2012, a PCE as high as 19.3% was demonstrated in 2014, and a certified PCE of 17.9% was shown in 2014. Such a high photovoltaic performance is attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths. Nevertheless, there are lots of puzzles to unravel the basis for such high photovoltaic performances. The working principle of perovskite solar cells has not been well established by far, which is the most important thing for understanding perovksite solar cells. In this review, basic fundamentals of perovskite materials including opto-electronic and dielectric properties are described to give a better understanding and insight into high-performing perovskite solar cells. In addition, various fabrication techniques and device structures are described toward the further improvement of perovskite solar cells. PMID:25358818

Jung, Hyun Suk; Park, Nam-Gyu

2015-01-01

194

Multijunction Solar Cells Optimized for the Mars Surface Solar Spectrum  

NASA Technical Reports Server (NTRS)

This paper gives an update on the performance of the Mars Exploration Rovers (MER) which have been continually performing for more than 3 years beyond their original 90-day missions. The paper also gives the latest results on the optimization of a multijunction solar cell that is optimized to give more power on the surface of Mars.

Edmondson, Kenneth M.; Fetzer, Chris; Karam, Nasser H.; Stella, Paul; Mardesich, Nick; Mueller, Robert

2007-01-01

195

Cardiff University Distinguished Lecture Symposium Advances in Solar Energy  

E-print Network

Cardiff University Distinguished Lecture Symposium Advances in Solar Energy Thursday 22nd March prospects for inorganic thin film photovoltaic solar cells for large scale energy generation 2:55 Dr Emyr:50 Professor James Durrant (Imperial College London, England) Photochemical approaches to solar energy

Martin, Ralph R.

196

Comparative values of advanced space solar cells  

NASA Technical Reports Server (NTRS)

A methodology for deriving a first order dollar value estimate for advanced solar cells which consists of defining scenarios for solar array production and launch to orbit and the associated costs for typical spacecraft, determining that portion affected by cell design and performance and determining the attributable cost differences is presented. Break even values are calculated for a variety of cells; confirming that efficiency and related effects of radiation resistance and temperature coefficient are major factors; array tare mass, packaging and packing factor are important; but cell mass is of lesser significance. Associated dollar values provide a means of comparison.

Slifer, L. W., Jr.

1982-01-01

197

Nanocrystalline silicon based thin film solar cells  

NASA Astrophysics Data System (ADS)

Amorphous silicon solar cells and panels on glass and flexible substrate are commercially available. Since last few years nanocrystalline silicon thin film has attracted remarkable attention due to its stability under light and ability to absorb longer wavelength portion of solar spectrum. For amorphous silicon/ nanocrystalline silicon double junction solar cell 14.7% efficiency has been achieved in small area and 13.5% for large area modules internationally. The device quality nanocrystalline silicon films have been fabricated by RF and VHF PECVD methods at IACS. Detailed characterizations of the materials have been done. Nanocrystalline films with low defect density and high stability have been developed and used as absorber layer of solar cells.

Ray, Swati

2012-06-01

198

Photochemical Production and Behavior of Hydroperoxyacids in Heterotrophic Bacteria Attached to Senescent Phytoplanktonic Cells  

PubMed Central

The photooxidation of cellular monounsaturated fatty acids was investigated in senescent phytoplanktonic cells (Emiliania huxleyi) and in their attached bacteria under laboratory controlled conditions. Our results indicated that UV-visible irradiation of phytodetritus induced the photooxidation of oleic (produced by phytoplankton and bacteria) and cis-vaccenic (specifically produced by bacteria) acids. These experiments confirmed the involvement of a substantial singlet oxygen transfer from senescent phytoplanktonic cells to attached bacteria, and revealed a significant correlation between the concentration of chlorophyll, a photosensitizer, in the phytodetritus and the photodegradation state of bacteria. Hydroperoxyacids (fatty acid photoproducts) appeared to be quickly degraded to ketoacids and hydroxyacids in bacteria and in phytoplanktonic cells. This degradation involves homolytic cleavage (most likely induced by UV and/or transition metal ions) and peroxygenase activity (yielding epoxy acids). PMID:23736689

Petit, Morgan; Sempr, Richard; Vaultier, Frdric; Rontani, Jean-Franois

2013-01-01

199

Nanoscale Charge Transport in Excitonic Solar Cells  

SciTech Connect

Excitonic solar cells, including all-organic, hybrid organic-inorganic and dye-sensitized solar cells (DSSCs), offer strong potential for inexpensive and large-area solar energy conversion. Unlike traditional inorganic semiconductor solar cells, where all the charge generation and collection processes are well understood, these excitonic solar cells contain extremely disordered structures with complex interfaces which results in large variations in nanoscale electronic properties and has a strong influence on carrier generation, transport, dissociation and collection. Detailed understanding of these processes is important for fabrication of highly efficient solar cells. Efforts to improve efficiency are underway at a large number of research groups throughout the world focused on inorganic and organic semiconductors, photonics, photophysics, charge transport, nanoscience, ultrafast spectroscopy, photonics, semiconductor processing, device physics, device structures, interface structure etc. Rapid progress in this multidisciplinary area requires strong synergetic efforts among researchers from diverse backgrounds. Such effort can lead to novel methods for development of new materials with improved photon harvesting and interfacial treatments for improved carrier transport, process optimization to yield ordered nanoscale morphologies with well defined electronic structures.

Venkat Bommisetty, South Dakota State University

2011-06-23

200

Advanced Solar Cells for Satellite Power Systems  

NASA Technical Reports Server (NTRS)

The multiple natures of today's space missions with regard to operational lifetime, orbital environment, cost and size of spacecraft, to name just a few, present such a broad range of performance requirements to be met by the solar array that no single design can suffice to meet them all. The result is a demand for development of specialized solar cell types that help to optimize overall satellite performance within a specified cost range for any given space mission. Historically, space solar array performance has been optimized for a given mission by tailoring the features of silicon solar cells to account for the orbital environment and average operating conditions expected during the mission. It has become necessary to turn to entirely new photovoltaic materials and device designs to meet the requirements of future missions, both in the near and far term. This paper will outline some of the mission drivers and resulting performance requirements that must be met by advanced solar cells, and provide an overview of some of the advanced cell technologies under development to meet them. The discussion will include high efficiency, radiation hard single junction cells; monolithic and mechanically stacked multiple bandgap cells; and thin film cells.

Flood, Dennis J.; Weinberg, Irving

1994-01-01

201

Nanoparticle Solar Cell Final Technical Report  

SciTech Connect

The purpose of this work was to demonstrate all-inorganic nanoparticle-based solar cells with photovoltaic performance extending into the near-IR region of the solar spectrum as a pathway towards improving power conversion efficiencies. The field of all-inorganic nanoparticle-based solar cells is very new, with only one literature publication in the prior to our project. Very little is understood regarding how these devices function. Inorganic solar cells with IR performance have previously been fabricated using traditional methods such as physical vapor deposition and sputtering, and solution-processed devices utilizing IR-absorbing organic polymers have been investigated. The solution-based deposition of nanoparticles offers the potential of a low-cost manufacturing process combined with the ability to tune the chemical synthesis and material properties to control the device properties. This work, in collaboration with the Sue Carter research group at the University of California, Santa Cruz, has greatly expanded the knowledge base in this field, exploring multiple material systems and several key areas of device physics including temperature, bandgap and electrode device behavior dependence, material morphological behavior, and the role of buffer layers. One publication has been accepted to Solar Energy Materials and Solar Cells pending minor revision and another two papers are being written now. While device performance in the near-IR did not reach the level anticipated at the beginning of this grant, we did observe one of the highest near-IR efficiencies for a nanoparticle-based solar cell device to date. We also identified several key parameters of importance for improving both near-IR performance and nanoparticle solar cells in general, and demonstrated multiple pathways which showed promise for future commercialization with further research.

Breeze, Alison, J; Sahoo, Yudhisthira; Reddy, Damoder; Sholin, Veronica; Carter, Sue

2008-06-17

202

MIS silicon solar cells: potential advantages  

SciTech Connect

Recent progress with silicon solar cells based on the MIS or SIS structure is reviewed. To be competitive with pn junction technology in the near term, these cells must be much cheaper or have a higher efficiency in a production environment. Apparently, the minority carrier MIS cells have the greatest potential for large-scale applications. The data currently indicate that all types of MIS/SIS cells have some inherent instability problems.

Cheek, G.; Mertens, R.

1981-05-01

203

Plastic Schottky-barrier solar cells  

DOEpatents

A photovoltaic cell structure is fabricated from an active medium including an undoped polyacetylene, organic semiconductor. When a film of such material is in rectifying contact with a metallic area electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates a magnesium layer on the undoped polyacetylene film. With the proper selection and location of elements a photovoltaic cell structure and solar cell are obtained.

Waldrop, J.R.; Cohen, M.J.

1981-12-30

204

Qualitative and quantitative evaluation of thin-film solar cells using solar cell local characterization  

NASA Astrophysics Data System (ADS)

The light-beam-induced current-based CELLO measurement technique (solar CELl LOcal characterization), originally developed for wafer-based silicon solar cells, can successfully be applied to thin-film solar cells, provided that contacting of a single cell is possible. This is shown exemplarily for several crystalline silicon on glass samples, having varying quality with respect to photocurrent extraction, series resistance, and power losses. For the latter, a comparison with results obtained from dark lock-in thermography gives quantitative agreement, provided that the cells are not severely shunted.

Wagner, J.-M.; Carstensen, J.; Schtt, A.; Fll, H.

2013-02-01

205

EE Times: Semi News Groups claim breakthroughs in solar cells  

E-print Network

claim to offer nearly twice the efficiency as silicon in solar cells. But solar cells based concentrator photovoltaic (CPV) modules for large- scale solar power generation. Semprius' microEE Times: Semi News Groups claim breakthroughs in solar cells Mark LaPedus Page 1 of 2 EE Times (05

Rogers, John A.

206

Third Working Meeting on Gallium Arsenide Solar Cells  

NASA Technical Reports Server (NTRS)

Research results are reported for GaAs Schottky barrier solar cells, GaAlAs/GaAs heteroface solar cells, and GaAlAs graded band gap solar cells. Related materials studies are presented. A systems study for GaAs and Si solar concentrator systems is given.

Walker, G. H. (compiler)

1976-01-01

207

November 21, 2000 PV Lesson Plan 1 Solar Cells  

E-print Network

November 21, 2000 PV Lesson Plan 1 ­ Solar Cells Prepared for the Oregon Million Solar Roofs High School Gary Grace ­ South Eugene High School In Schools #12;1 Solar Cells Lesson Plan Content: In this lesson, students are introduced to the basic physics and chemistry behind the operation of a solar cell

Oregon, University of

208

Microstructural analysis of solar cell welds  

NASA Astrophysics Data System (ADS)

Parallel-gap resistance welding of silicon solar cells with copper interconnects results in complex microstructural variations that depend on the welding variables. At relatively low heat input solid-state welds are produced. At medium heat the Ag-Cu eutectic forms resulting in a braze joint. High heat produces a fusion weld with complete melting of the silver layer on the silicon solar cell. If the silicon is also melted, cracking occurs in the silicon cell below the weld nugget. These determinations were made using light microscopy, microprobe, and scanning electron microscopy analyses.

Moore, T. J.; Watson, G. K.; Baraona, C. R.

209

Microscopic optoelectronic defectoscopy of solar cells  

NASA Astrophysics Data System (ADS)

Scanning probe microscopes are powerful tool for micro- or nanoscale diagnostics of defects in crystalline silicon solar cells. Solar cell is a large p-n junction semiconductor device. Its quality is strongly damaged by the presence of defects. If the cell works under low reverse-biased voltage, defects emit a light in visible range. The suggested method combines three different measurements: electric noise measurement, local topography and near-field optical beam induced current and thus provides more complex information. To prove its feasibility, we have selected one defect (truncated pyramid) in the sample, which emitted light under low reverse-biased voltage.

karvada, P.; Tomnek, P.; Koktav, P.; Dallaeva, D.

2013-04-01

210

Progress in semicrystalline silicon solar cell fabrication  

NASA Astrophysics Data System (ADS)

Several recent advances made in the fabrication technology of semicrystalline silicon solar cells are reviewed in this paper. Recent work has indicated that: (1) semicrystalline silicon solar cell performance is mainly controlled by intragrain defect densities and not only by the grain boundaries, (2) processing parameters for low cost, high throughput techniques require more optimization when semicrystalline silicon substrates are used, and (3) reasonable cell efficiencies have been achieved using a low cost thin-film epitaxial layer on UMG-Silicon coupled with low cost screen printing technology.

Mertens, R.; Cheek, G.; Depauw, P.; Frisson, L.

211

Understanding intermediate-band solar cells  

Microsoft Academic Search

The intermediate-band solar cell is designed to provide a large photogenerated current while maintaining a high output voltage. To make this possible, these cells incorporate an energy band that is partially filled with electrons within the forbidden bandgap of a semiconductor. Photons with insufficient energy to pump electrons from the valence band to the conduction band can use this intermediate

Antonio Mart; Colin Stanley; Antonio Luque

2012-01-01

212

Glass tubes for protecting solar cells  

NASA Technical Reports Server (NTRS)

Protecting solar cells against environmental effects is accomplished by putting them inside glass tubes instead of hermetically sealing them between pairs of flat glass sheets. If cells are coupled with storage battery integrated into tube, freestanding power source could be built.

Shelpuk, B.

1978-01-01

213

Liquid cooled, linear focus solar cell receiver  

DOEpatents

Separate structures for electrical insulation and thermal conduction are established within a liquid cooled, linear focus solar cell receiver for use with parabolic or Fresnel optical concentrators. The receiver includes a V-shaped aluminum extrusion having a pair of outer faces each formed with a channel receiving a string of solar cells in thermal contact with the extrusion. Each cell string is attached to a continuous glass cover secured within the channel with spring clips to isolate the string from the external environment. Repair or replacement of solar cells is effected simply by detaching the spring clips to remove the cover/cell assembly without interrupting circulation of coolant fluid through the receiver. The lower surface of the channel in thermal contact with the cells of the string is anodized to establish a suitable standoff voltage capability between the cells and the extrusion. Primary electrical insulation is provided by a dielectric tape disposed between the coolant tube and extrusion. Adjacent solar cells are soldered to interconnect members designed to accommodate thermal expansion and mismatches. The coolant tube is clamped into the extrusion channel with a releasably attachable clamping strip to facilitate easy removal of the receiver from the coolant circuit.

Kirpich, A.S.

1983-12-08

214

Liquid cooled, linear focus solar cell receiver  

DOEpatents

Separate structures for electrical insulation and thermal conduction are established within a liquid cooled, linear focus solar cell receiver for use with parabolic or Fresnel optical concentrators. The receiver includes a V-shaped aluminum extrusion having a pair of outer faces each formed with a channel receiving a string of solar cells in thermal contact with the extrusion. Each cell string is attached to a continuous glass cover secured within the channel with spring clips to isolate the string from the external environment. Repair or replacement of solar cells is effected simply by detaching the spring clips to remove the cover/cell assembly without interrupting circulation of coolant fluid through the receiver. The lower surface of the channel in thermal contact with the cells of the string is anodized to establish a suitable standoff voltage capability between the cells and the extrusion. Primary electrical insulation is provided by a dielectric tape disposed between the coolant tube and extrusion. Adjacent solar cells are soldered to interconnect members designed to accommodate thermal expansion and mismatches. The coolant tube is clamped into the extrusion channel with a releasably attachable clamping strip to facilitate easy removal of the receiver from the coolant circuit.

Kirpich, Aaron S. (Broomall, PA)

1985-01-01

215

Method of restoring degraded solar cells  

DOEpatents

Amorphous silicon solar cells have been shown to have efficiencies which degrade as a result of long exposure to light. Annealing such cells in air at a temperature of about 200.degree. C. for at least 30 minutes restores their efficiency.

Staebler, David L. (Lawrenceville, NJ)

1983-01-01

216

Solar Cell Calibration and Measurement Techniques  

NASA Technical Reports Server (NTRS)

The increasing complexity of space solar cells and the increasing international markets for both cells and arrays has resulted in workshops jointly sponsored by NASDA, ESA and NASA. These workshops are designed to obtain international agreement on standardized values for the AMO spectrum and constant, recommend laboratory measurement practices and establish a set of protocols for international comparison of laboratory measurements. A working draft of an ISO standard, WDI 5387, 'Requirements for Measurement and Calibration Procedures for Space Solar Cells' was discussed with a focus on the scope of the document, a definition of primary standard cell, and required error analysis for all measurement techniques. Working groups addressed the issues of Air Mass Zero (AMO) solar constant and spectrum, laboratory measurement techniques, and the international round robin methodology. A summary is presented of the current state of each area and the formulation of the ISO document.

Bailey, Sheila; Brinker, Dave; Curtis, Henry; Jenkins, Phillip; Scheiman, Dave

1997-01-01

217

High efficiency low cost solar cell power  

NASA Technical Reports Server (NTRS)

A concept for generating high-efficiency, low-cost, solar-cell power is outlined with reference to solar cell parameters, optical concentrators, and thermal control procedures. A design for a 12.5-kw power module for space operation is discussed noting the optical system, spectrum splitter, light conversion system, cell cooling, power conditioner, and tracking mechanism. It is found that for an unconcentrated array, efficiency approaches 60% when ten or more bandgaps are used. For a 12-band system, a computer program distributed bandgaps for maximum efficiency and equal cell currents. Rigid materials and thin films have been proposed for optical components and prisms, gratings, and dichroic mirrors have been recommended for spectrum splitting. Various radiator concepts are noted including that of Weatherston and Smith (1960) and Hedgepeth and Knapp (1978). The concept may be suitable for the Solar Power Satellite.

Bekey, I.; Blocker, W.

1978-01-01

218

GaAs solar cell test facility  

NASA Astrophysics Data System (ADS)

A hybrid type (electricity and heat) GaAs solar cell test facility has been made to evaluate total characteristics of GaAs cell and to study the energy conversion system. The size of a solar collector is 3.4 m x 2.1 m and 60 GaAs cells with Fresnel lenses are attached on it. The solar collector is controlled by a microcomputer to track the sun. Electric energy produced by the cells is stored in a lead-acid battery and then supplied to the load through a DC-AC inverter. The microcomputer also controls the data acquisition in parallel with tracking. This paper presents an overview of the facility and the experimental results of power generation obtained to date.

Kawashima, M.; Hosoda, Y.; Suzawa, C.; Shimada, T.; Motoyoshi, K.; Sasatani, Y.

1982-01-01

219

T cell and B Cell immunity can be reconstituted with mismatched hematopoietic stem cell transplantation without alkylator therapy in artemis-deficient mice using anti-natural killer cell antibody and photochemically treated sensitized donor T cells.  

PubMed

Children with Artemis-deficient T(-)B(-)NK(+) severe combined immunodeficiency are at high risk for graft rejection from natural killer (NK) cells and toxicity from increased sensitivity to the alkylating agents used in mismatched hematopoietic stem cell transplantation (HSCT). We evaluated the use of a nonalkylating agent regimen before HSCT in Artemis-deficient (mArt(-/-)) C57Bl/6 (B6) mice to open marrow niches and achieve long-term multilineage engraftment with full T cell and B cell immune reconstitution. We found that partial depletion of both recipient NK cells using anti-NK1.1 monoclonal antibody and donor T cells sensitized to recipient splenocytes was necessary. BALB/c-sensitized T cells (STCs) were photochemically treated (PCT) with psoralen and UVA light to inhibit proliferation, reduce the risk of graft-versus-host disease (GVHD), and target host hematopoietic stem cells (HSCs). A dose of 4 10(5) PCT STCs coinjected with 1 10(5) lineage-depleted c-kit(+) BALB/c HSCs resulted in 43.9% 3.3% CD4(+) and 10.9% 1.2% CD8(+) donor T cells in blood, 29% 7.8% and 21.7% 4.0 donor B220(+) IgM(+) in spleen and bone marrow, and 15.0% 3.6% donor Gran-1(+) cells in bone marrow at 6 months post-HSCT versus 0.02% 0.01%, 0.13% 0.10%, 0.53% 0.16%, 0.49% 0.09%, and 0.20% 0.06%, respectively, in controls who did not receive PCT STCs. We found that STCs target host HSCs and that PCT STCs are detectable only up to 24 hours after infusion, in contrast to non-photochemically treated STCs, which proliferate resulting in fatal GVHD. Increased mortality in the groups receiving 4-6 10(5) PCT STCs was associated with evidence of GVHD, particularly in the recipients of 6 10(5) cells. These results demonstrate that blocking NK cell-mediated resistance and making niches in bone marrow are both essential to achieving multilineage engraftment of mismatched donor cells and T cell and B cell reconstitution, even though GVHD is not completely eliminated. PMID:22015994

Xiao, Tony Z; Singh, Kanal; Dunn, Elizabeth; Ramachandran, Rageshree; Cowan, Morton J

2012-02-01

220

Silicon solar cell process. Development, fabrication and analysis  

NASA Technical Reports Server (NTRS)

Solar cells were fabricated from unconventional silicon sheets, and the performances were characterized with an emphasis on statistical evaluation. A number of solar cell fabrication processes were used and conversion efficiency was measured under AMO condition at 25 C. Silso solar cells using standard processing showed an average efficiency of about 9.6%. Solar cells with back surface field process showed about the same efficiency as the cells from standard process. Solar cells from grain boundary passivation process did not show any improvements in solar cell performance.

Yoo, H. I.; Iles, P. A.; Tanner, D. P.

1978-01-01

221

Printable CIGS thin film solar cells  

NASA Astrophysics Data System (ADS)

Among the various thin film solar cells in the market, CuInGaSe thin film solar cells have been considered as the most promising alternatives to crystalline silicon solar cells because of their high photo-electricity conversion efficiency, reliability, and stability. However, many fabrication methods of CIGS thin film are based on vacuum processes such as evaporation and sputtering techniques which are not cost efficient. This work develops a solution method using paste or ink liquid spin-coated on glass that would be competitive to conventional ways in terms of cost effective, non-vacuum needed, and quick processing. A mixture precursor was prepared by dissolving appropriate amounts of composition chemicals. After the mixture solution was cooled, a viscous paste was prepared and ready for spin-coating process. A slight bluish CIG thin film on substrate was then put in a tube furnace with evaporation of metal Se followed by depositing CdS layer and ZnO nanoparticle thin film coating to complete a solar cell fabrication. Structure, absorption spectrum, and photo-electricity conversion efficiency for the as-grown CIGS thin film solar cell are under study.

Fan, Xiaojuan

2013-03-01

222

Quantum-Tuned Multijunction Solar Cells  

NASA Astrophysics Data System (ADS)

Multijunction solar cells made from a combination of CQDs of differing sizes and thus bandgaps are a promising means by which to increase the energy harvested from the Sun's broad spectrum. In this dissertation, we first report the systematic engineering of 1.6 eV PbS CQD solar cells, optimal as the front cell responsible for visible wavelength harvesting in tandem photovoltaics. We rationally optimize each of the device's collecting electrodes---the heterointerface with electron accepting TiO2 and the deep-work-function hole-collecting MoO3 for ohmic contact---for maximum efficiency. Room-temperature processing enables flexible substrates, and permits tandem solar cells that integrate a small-bandgap back cell atop a low thermal-budget larger-bandgap front cell. We report an electrode strategy that enables a depleted heterojunction CQD PV device to be fabricated entirely at room temperature. We develop a two-layer donor-supply electrode (DSE) in which a highly doped, shallow work function layer supplies a high density of free electrons to an ultrathin TiO2 layer via charge-transfer doping. Using the DSE we build all-room-temperature-processed small-bandgap (1 eV) colloidal quantum dot solar cells suitable for use as the back junction in tandem solar cells. We further report in this work the first efficient CQD tandem solar cells. We use a graded recombination layer (GRL) to provide a progression of work functions from the hole-accepting electrode in the bottom cell to the electron-accepting electrode in the top cell. The recombination layers must allow the hole current from one cell to recombine, with high efficiency and low voltage loss, with the electron current from the next cell. We conclude our dissertation by presenting the generalized conditions for design of efficient graded recombination layer solar devices. We demonstrate a family of new GRL designs experimentally and highlight the benefits of the progression of dopings and work functions in the interlayers.

Koleilat, Ghada I.

223

High voltage solar cell power generating system  

NASA Technical Reports Server (NTRS)

A laboratory solar power system regulated by on-panel switches has been delivered for operating high power (3 kW), high voltage (15,000 volt) loads (communication tubes, ion thrusters). The modular system consists of 26 solar arrays, each with an integral light source and cooling system. A typical array contains 2,560 series-connected cells. Each light source consists of twenty 500-watt tungsten iodide lamps providing plus or minus 5 percent uniformity at one solar constant. An array temperature of less than 40 C is achieved using an infrared filter, a water-cooled plate, a vacuum hold-down system, and air flushing.

Levy, E., Jr.; Opjorden, R. W.; Hoffman, A. C.

1974-01-01

224

Efficient organic solar cells based on phthalocyanines  

NASA Astrophysics Data System (ADS)

The primary goal of this thesis is to develop efficient organic solar cells by utilizing metallophthalocyanines (MPc) as donor materials. The role of centered metals in MPcs is discussed, and it is shown that a suitable choice of centered metals and device engineering lead to efficient MPc based solar cells. The effect of molecular packing of organic semiconductors on interfacial recombination at a donor/acceptor interface is also discussed. Organic solar cells based on planar metallophthalocyanines (MPc, M = Cu, Zn, Pd, Pc)/3,4,9,10-perylene tetracarboxylic bisbenzimidazole (PTCBI) are investigated. PdPc/PTCBI solar cells have a peak external quantum efficiency of 30.9%, which is almost two times larger than solar cells based on CuPc/PTCBI and ZnPc/PTCBI. External quantum efficiency measurement and optical modeling indicate that PdPc has longer exciton diffusion length than CuPc and ZnPc, leading to an enhanced efficiency. Device performance of organic solar cells consisting of ZnPc and fullerene (C60) can be enhanced by insertion of a N,N'-dihexyl-perylene-3,4,9,10-bis(dicarboximide) (PTCDI-C6) intermediate layer between fullerene and bathocuproine (BCP) exciton blocking layer. Insertion of the PTCDI-C6 layer between fullerene and BCP enhances an efficiency from 1.9 to 2.5%. The enhancement in device performances by insertion of PTCDI-C6 is attributed to reduction in device series resistances due to the promoted metal migration into BCP and optimized optical interference effects in multi-layered devices. Electron-hole pair recombination at donor/acceptor interfaces was discussed for PdPc/PTCDI derivatives solar cells with correlation of molecular packing in PTCDI derivatives. PTCDI with hexyl chains exhibits the highest charge separation efficiency among three PTCDI derivatives. Lastly, it is demonstrated that a power conversion efficiency of p-i-n type organic solar cells consisting of ZnPc and C60 can be enhanced by replacing ZnPc p-layer with PdPc. The optimized cell consisting of PdPc/ZnPc:C60/C60 exhibited an efficiency of 3.7%, while the cell with the device structure of ZnPc/ZnPc:C 60/C60 showed 3.2%. The enhancement in the efficiency is mainly attributed to increase in the short circuit current density, which is due to PdPc p-layer having longer exciton diffusion length than ZnPc.

Kim, Inho

225

One-sun silicon solar cell research  

Microsoft Academic Search

This report describes research for the period September 1988 to February 1990 directed at improving the performance of crystalline and polycrystalline silicon solar cells. Key results include the demonstration of 24.2 percent energy conversion efficiency for 4-sq cm crystalline cells fabricated using the development of the Passivated Emitter Cell processing sequence, the demonstration of energy conversion efficiency up to 22.4

M. A. Green; J. Zhao; A. Wang; A. W. Blakers; A. M. Milne; X. Dai; C. M. Chong; S. R. Wenham; F. Zhang; F. Yun; J. Zolper; S. Narayanan; A. B. Sproul

1991-01-01

226

Fracture strength of silicon solar cells  

NASA Technical Reports Server (NTRS)

A test program was developed to determine the nature and source of the flaw controlling the fracture of silicon solar cells and to provide information regarding the mechanical strength of cells. Significant changes in fracture strengths were found in seven selected in-process wafer-to-cell products from a manufacturer's production line. The fracture strength data were statistically analyzed and interpreted in light of the exterior flaw distribution of the samples.

Chen, C. P.

1979-01-01

227

InP concentrator solar cells  

Microsoft Academic Search

The design, fabrication, and characterization of high-performance, n+\\/p InP shallow-homojunction (SHJ) concentrator solar cells are described. The InP device structures were grown by atmospheric-pressure metalorganic vapor phase epitaxy (APMOVPE). A preliminary assessment of the effects of grid collection distance and emitter sheet resistance on cell performance is presented. At concentration ratios of around 100, cells with efficiencies of 21.4% AM0

J. S. Ward; M. W. Wanlass; T. J. Coutts; K. A. Emery; C. R. Osterwald

1991-01-01

228

Feasibility of low cost silicon solar cells.  

NASA Technical Reports Server (NTRS)

Future costs of silicon solar cells are projected on the basis of more than a thousand-fold increase in volume. If no major application of new manufacturing technology is made, the cost remains excessive for any large scale energy system. However, the development of a multiple-ribbon crystal growth process could permit a 300-fold reduction in cell costs to about $375/kW of cell output.

Currin, C. G.; Smith, W. A.; Ling, K. S.; Ralph, E. L.; Stirn, R. J.

1972-01-01

229

Excimer micromachining for texturing silicon solar cells  

Microsoft Academic Search

Recent improvements in 'surface engineering' have helped to increase one-sun silicon solar cell efficiencies to more than 24% for float-zone grown single-crystal silicon. Texturing of the cell surface, to enhance the light coupling into cell, constitutes a significant part of this dramatic progress. Most single-crystal silicon substrates with a (100) surface orientation can be textured with relative ease using a

Ugur Ortabasi; Daniel L. Meier; John R. Easoz; Ronald D. Schaeffer; Maria A. Stepanova; Wen Ho; Jeffrey A. Stokes; Richard S. Dummer; James C. Jafolla; Paul McKenna

1997-01-01

230

Towards highly efficient solar cells  

NASA Astrophysics Data System (ADS)

Suntech Power is the world's largest producer of solar panels and has delivered more than 20 million photovoltaic panels to more than 80 countries around the globe. Nature Photonics spoke with Stuart Wenham, chief technology officer at Suntech Power, to find out more about its activities and visions.

2012-03-01

231

Plasmonic ITO-free polymer solar cell.  

PubMed

The aluminum and sliver multilayered nano-grating structure is fabricated by laser interference lithography and the intervals between nanoslits is filled with modified PEDOT:PSS. The grating structured transparent electrode functions as the anti-reflection layer which not only decreases the reflected light but also increases the absorption of the active layer. The performances of P3HT:PC??BM solar cells are studied experimentally and theoretically in detail. The field intensities of the transverse magnetic (TM) and transverse electrical (TE) waves distributed in the active layer are simulated by rigorous coupled wave analysis (RCWA). The power conversion efficiency of the plasmonic ITO-free polymer solar cell can reach 3.64% which is higher than ITO based polymer solar cell with efficiency of 3.45%. PMID:24922253

Lin, Ming-Yi; Kang, Yu Ling; Chen, Yu-Cheng; Tsai, Tsung-Han; Lin, Shih-Chieh; Huang, Yi-Hsiang; Chen, Yi-Jiun; Lu, Chun-Yang; Lin, Hoang Yan; Wang, Lon A; Wu, Chung-Chih; Lee, Si-Chen

2014-03-10

232

Fabricating solar cells with silicon nanoparticles  

DOEpatents

A laser contact process is employed to form contact holes to emitters of a solar cell. Doped silicon nanoparticles are formed over a substrate of the solar cell. The surface of individual or clusters of silicon nanoparticles is coated with a nanoparticle passivation film. Contact holes to emitters of the solar cell are formed by impinging a laser beam on the passivated silicon nanoparticles. For example, the laser contact process may be a laser ablation process. In that case, the emitters may be formed by diffusing dopants from the silicon nanoparticles prior to forming the contact holes to the emitters. As another example, the laser contact process may be a laser melting process whereby portions of the silicon nanoparticles are melted to form the emitters and contact holes to the emitters.

Loscutoff, Paul; Molesa, Steve; Kim, Taeseok

2014-09-02

233

Space solar cell research: Problems and potential  

NASA Technical Reports Server (NTRS)

The value of a passive, maintenance-free, renewable energy source was apparent in the early days of the space program, and the silicon solar cell was pressed into service. Efficiencies of those early space solar arrays were low, and lifetimes shorter than hoped for, but within a decade significant advances had been made in both areas. Better performance was achieved through improvements in silicon single crystal material, better device designs, and a better understanding of the factors that affect the performance of a solar cell in space. Chief among the latter, particularly for the mid-to-high altitude (HEO) and geosynchronous (GEO) orbits, are the effects of the naturally occurring particulate radiation environment. Although not as broadly important to the photovoltaic community at large as increased efficiency, the topic of radiation damage is critically important to use of solar cells in space, and is a major component of the NASA research program in space photovoltaics. A brief overview of some of the opportunities and challenges for space photovoltaic applications is given, and some of the current research directed at achieving high efficiency and controlling radiation damage in space solar cells is discussed.

Flood, D. J.

1986-01-01

234

Space solar cell research - Problems and potential  

NASA Technical Reports Server (NTRS)

The value of a passive, maintenance-free, renewable energy source was immediately recognized in the early days of the space program, and the silicon solar cell, despite its infancy, was quickly pressed into service. Efficiencies of those early space solar arrays were low, and lifetimes shorter than hoped for, but within a decade significant advances had been made in both areas. Better performance was achieved because of a variety of factors, ranging from improvements in silicon single crystal material, to better device designs, to a better understanding of the factors that affect the performance of a solar cell in space. Chief among the latter, particularly for the mid-to-high altitude (HEO) and geosynchronous (GEO) orbits, are the effects of the naturally occurring particulate radiation environment. Although not as broadly important to the photovoltaic community at large as increased efficiency, the topic of radiation damage is critically important to use of solar cells in space, and is a major component of the NASA research program in space photovoltaics. This paper will give a brief overview of some of the opportunities and challenges for space photovoltaic applications, and will discuss some of the current reseach directed at achieving high efficiency and controlling the effects of radiation damage in space solar cells.

Flood, Dennis J.

1986-01-01

235

Metallization for large-area solar cells  

NASA Technical Reports Server (NTRS)

In large area, low cost solar cells of any type, the contact and grid structure metallization is an important factor which has an effect on the efficiency of the solar cell and its reliability. The present investigation is concerned with aspects of solar cell efficiency. An optimized metallization design leads to minimum total power loss, which is related to a simultaneous minimization of ohmic voltage drops and of shading of the front surface of the cell by the overlaid metal. The requirements regarding the design for a low-loss metallization pattern for the front surface of large area solar cells are represented by a set of design rules listed in a table. The total shading and voltage drop on such cells can be held to about 5%. However, not every metallization process is suited for meeting the requirements of the low-cost design. The low losses can be achieved only by use of several bus lines containing a bulk conductor, such as a wire.

Wolf, M.

1981-01-01

236

Amorphous thin films for solar-cell applications  

Microsoft Academic Search

A research program on hydrogenated amorphous silicon (a-Si:H) and the a-Si:H solar cell is described. Theoretical modeling, deposition and doping studies, experimental methods for the characterization of a-Si:H, formation of solar cell structures, theoretical and experimental evaluation of solar cell parameters, and an investigation of stacked junction cells are discussed.

D. E. Carlson; R. S. Crandall; J. Dresner; B. Goldstein; J. J. Hanak; J. I. Pankove; H. E. Schade; D. L. Staebler; H. A. Weakliem; R. Williams

1980-01-01

237

Optimal geometric design of monolithic thin-film solar modules: Architecture of polymer solar cells  

Microsoft Academic Search

In this study the geometrical optimization of monolithically integrated solar cells into serially connected solar modules is reported. Based on the experimental determination of electrodes? sheet and intermittent contact resistances, the overall series resistance of individual solar cells and interconnected solar modules is calculated. Taking a constant photocurrent generation density into account, the total Joule respectively resistive power losses are

Harald Hoppe; Marco Seeland; Burhan Muhsin

238

NanoSense: Solar Cell Animation  

NSDL National Science Digital Library

This Flash animation depicts the function of two types of solar cell systems: a silicon-based cell and a dye-sensitized cell. Both systems convert light energy to electrical energy, but the structure is quite different. The silicon-based cell is a solid-state semiconductor that employs two crystalline silicon layers between metal conducting strips. The dye-sensitized cell consists of a layer of titanium dioxide nanoparticles bonded to a layer of organic dye, and immersed in an electrolyte solution. Both systems excite electrons, which are directed to conducting strips and flow through a wire as electric current.

2013-04-19

239

High throughput solar cell ablation system  

DOEpatents

A solar cell is formed using a solar cell ablation system. The ablation system includes a single laser source and several laser scanners. The laser scanners include a master laser scanner, with the rest of the laser scanners being slaved to the master laser scanner. A laser beam from the laser source is split into several laser beams, with the laser beams being scanned onto corresponding wafers using the laser scanners in accordance with one or more patterns. The laser beams may be scanned on the wafers using the same or different power levels of the laser source.

Harley, Gabriel; Pass, Thomas; Cousins, Peter John; Viatella, John

2014-10-14

240

High throughput solar cell ablation system  

DOEpatents

A solar cell is formed using a solar cell ablation system. The ablation system includes a single laser source and several laser scanners. The laser scanners include a master laser scanner, with the rest of the laser scanners being slaved to the master laser scanner. A laser beam from the laser source is split into several laser beams, with the laser beams being scanned onto corresponding wafers using the laser scanners in accordance with one or more patterns. The laser beams may be scanned on the wafers using the same or different power levels of the laser source.

Harley, Gabriel; Pass, Thomas; Cousins, Peter John; Viatella, John

2012-09-11

241

Solar cell having improved back surface reflector  

NASA Technical Reports Server (NTRS)

The operating temperature is reduced and the output of a solar cell is increased by using a solar cell which carries electrodes in a grid finger pattern on its back surface. These electrodes are sintered at the proper temperature to provide good ohmic contact. After sintering, a reflective material is deposited on the back surface by vacuum evaporation. Thus, the application of the back surface reflector is separate from the back contact formation. Back surface reflectors formed in conjunction with separate grid finger configuration back contacts are more effective than those formed by full back metallization of the reflector material.

Chai, A. T. (inventor)

1982-01-01

242

Impedance spectroscopic characterization of solar cell  

NASA Astrophysics Data System (ADS)

Impedance spectroscopy is used to characterize a commercial solar cell, at various dc bias potentials, under illumination and dark conditions. Interesting features are observed in medium and low frequency range, at large bias potentials. All the models reported in literature utilize combinations of resistances and capacitances, but the results indicate that inductances are necessary to model the actual solar cell, since an inductive loop is observed in the medium frequency range, especially at large bias potential, both under illumination and dark conditions. A new circuit which captures all the trends semi quantitatively is proposed to model the data.

Gautham, S.; Ramanathan, S.

2014-10-01

243

Origami-enabled deformable silicon solar cells  

SciTech Connect

Deformable electronics have found various applications and elastomeric materials have been widely used to reach flexibility and stretchability. In this Letter, we report an alternative approach to enable deformability through origami. In this approach, the deformability is achieved through folding and unfolding at the creases while the functional devices do not experience strain. We have demonstrated an example of origami-enabled silicon solar cells and showed that this solar cell can reach up to 644% areal compactness while maintaining reasonable good performance upon cyclic folding/unfolding. This approach opens an alternative direction of producing flexible, stretchable, and deformable electronics.

Tang, Rui; Huang, Hai; Liang, Hanshuang; Liang, Mengbing [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Tu, Hongen; Xu, Yong [Electrical and Computer Engineering, Wayne State University, 5050 Anthony Wayne Dr., Detroit, Michigan 48202 (United States); Song, Zeming; Jiang, Hanqing, E-mail: hanqing.jiang@asu.edu [School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287 (United States); Yu, Hongyu, E-mail: hongyu.yu@asu.edu [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287 (United States); School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287 (United States)

2014-02-24

244

Solar cell contact formation using laser ablation  

DOEpatents

The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline materiat layer; and forming conductive contacts in the plurality of contact holes.

Harley, Gabriel; Smith, David D.; Cousins, Peter John

2014-07-22

245

Solar cell contact formation using laser ablation  

DOEpatents

The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

Harley, Gabriel; Smith, David; Cousins, Peter

2012-12-04

246

Oxide heterostructures for ecient solar cells  

SciTech Connect

We propose an unexplored class of absorbing materials for high-efficiency solar cells: heterostructures of transition-metal oxides. In particular, LaVO3 grown on SrTiO3 has a direct band gap ~1.1 eV in the optimal range as well as an internal potential gradient, which can greatly help to separate the photogenerated electron-hole pairs. Furthermore, oxide heterostructures afford the flexibility to combine LaVO3 with other materials such as LaFeO3 in order to achieve even higher efficiencies with band-gap graded solar cells. We use density-functional theory to demonstrate these features.

Assmann, E. [Vienna University of Technology, Austria; Blaha, P. [Institute for Materials Chemistry, TU Vienna; Laskowski, R [Institute for Materials Chemistry, TU Vienna; Held, K. [Vienna University of Technology, Austria; Okamoto, Satoshi [ORNL; Sangiovanni, G. [University of Wuerzburg, Germany

2013-01-01

247

Solar recharging system for hearing aid cells.  

PubMed

We present a solar recharging system for nickel-cadmium cells of interest in areas where batteries for hearing aids are difficult to obtain. The charger has sun cells at the top. Luminous energy is converted into electrical energy, during the day and also at night if there is moonlight. The cost of the charger and hearing aid is very low at 35 US$. The use of solar recharging for hearing aids would be useful in alleviating the problems of deafness in parts of developing countries where there is no electricity. PMID:7964140

Gmez Estancona, N; Tena, A G; Torca, J; Urruticoechea, L; Muiz, L; Aristimuo, D; Unanue, J M; Torca, J; Urruticoechea, A

1994-09-01

248

Back surface reflectors for solar cells  

NASA Technical Reports Server (NTRS)

Sample solar cells were fabricated to study the effects of various back surface reflectors on the device performance. They are typical 50 micrometers thick, space quality, silicon solar cells except for variations of the back contact configuration. The back surfaces of the sample cells are polished to a mirror like finish, and have either conventional full contacts or grid finger contacts. Measurements and evaluation of various metallic back surface reflectors, as well as cells with total internal reflection, are presented. Results indicate that back surface reflectors formed using a grid finger back contact are more effective reflectors than cells with full back metallization and that Au, Ag, or Cu are better back surface reflector metals than Al.

Chai, A. T.

1980-01-01

249

InP concentrator solar cells  

NASA Technical Reports Server (NTRS)

The design, fabrication, and characterization of high-performance, n(+)/p InP shallow-homojunction (SHJ) concentrator solar cells are described. The InP device structures were grown by atmospheric-pressure metalorganic vapor phase epitaxy. A preliminary assessment of the effects of grid-collection distance and emitter-sheet resistance on cell performance is presented. At concentration ratios of around 100, cells with efficiencies of 21.4 percent AM0 (24.3 percent direct) at 25 C are fabricated. These are the highest efficiencies yet reported for single-junction InP solar cells. The performance of these cells as a function of temperature is discussed, and areas for future improvement are outlined. Application of these results to other InP-based photovoltaic devices is discussed.

Ward, J. S.; Wanlass, M. W.; Coutts, T. J.; Emery, K. A.; Osterwald, C. R.

1991-01-01

250

Detecting Solar-Cell Failures  

NASA Technical Reports Server (NTRS)

Circuit identified malfunctioning photovoltaic array. Cell-failure detection circuit compares output of photovoltaic array to control cell. If any module fails, activates light-emitting diode. Circuit could also sound alarm.

Maloney, T. J.

1983-01-01

251

Multi-junction solar cell device  

DOEpatents

A multi-junction solar cell device (10) is provided. The multi-junction solar cell device (10) comprises either two or three active solar cells connected in series in a monolithic structure. The multi-junction device (10) comprises a bottom active cell (20) having a single-crystal silicon substrate base and an emitter layer (23). The multi-junction device (10) further comprises one or two subsequent active cells each having a base layer (32) and an emitter layer (23) with interconnecting tunnel junctions between each active cell. At least one layer that forms each of the top and middle active cells is composed of a single-crystal III-V semiconductor alloy that is substantially lattice-matched to the silicon substrate (22). The polarity of the active p-n junction cells is either p-on-n or n-on-p. The present invention further includes a method for substantially lattice matching single-crystal III-V semiconductor layers with the silicon substrate (22) by including boron and/or nitrogen in the chemical structure of these layers.

Friedman, Daniel J. (Lakewood, CO); Geisz, John F. (Wheat Ridge, CO)

2007-12-18

252

Stratospheric NO and NO2 profiles at sunset from analysis of high-resolution balloon-borne infrared solar absorption spectra obtained at 33 deg N and calculations with a time-dependent photochemical model  

NASA Technical Reports Server (NTRS)

Simultaneous stratospheric vertical profiles of NO and NO2 at sunset were derived from an analysis of infrared solar absorption spectra recorded from a float altitude of 33 km with an interferometer system during a balloon flight. A nonlinear least squares procedure was used to analyze the spectral data in regions of absorption by NO and NO2 lines. Normalized factors, determined from calculations of time dependent altitude profiles with a detailed photochemical model, were included in the onion peeling analysis to correct for the rapid diurnal changes in NO and NO2 concentrations with time near sunset. The CO2 profile was also derived from the analysis and is reported.

Rinsland, C. P.; Boughner, R. E.; Larsen, J. C.; Goldman, A.; Murcray, F. J.; Murcray, D. G.

1984-01-01

253

Stratospheric NO and NO2 profiles at sunset from analysis of high-resolution balloon-borne infrared solar absorption spectra obtained at 33 deg N and calculations with a time-dependent photochemical model  

SciTech Connect

Simultaneous stratospheric vertical profiles of NO and NO2 at sunset were derived from an analysis of infrared solar absorption spectra recorded from a float altitude of 33 km with an interferometer system during a balloon flight. A nonlinear least squares procedure was used to analyze the spectral data in regions of absorption by NO and NO2 lines. Normalized factors, determined from calculations of time dependent altitude profiles with a detailed photochemical model, were included in the onion peeling analysis to correct for the rapid diurnal changes in NO and NO2 concentrations with time near sunset. The CO2 profile was also derived from the analysis and is reported.

Rinsland, C.P.; Boughner, R.E.; Larsen, J.C.; Goldman, A.

1984-08-01

254

Evaluation of solar cells for potential space satellite power applications  

NASA Technical Reports Server (NTRS)

The evaluation focused on the following subjects: (1) the relative merits of alternative solar cell materials, based on performance and availability, (2) the best manufacturing methods for various solar cell options and the effects of extremely large production volumes on their ultimate costs and operational characteristics, (3) the areas of uncertainty in achieving large solar cell production volumes, (4) the effects of concentration ratios on solar array mass and system performance, (5) the factors influencing solar cell life in the radiation environment during transport to and in geosynchronous orbit, and (6) the merits of conducting solar cell manufacturing operations in space.

1977-01-01

255

The properties and production of solar cells  

NASA Astrophysics Data System (ADS)

The operational characteristics, techniques of large scale production, the use, and materials for solar cells are reviewed. Attention is given to optimizing cell performance. A maximum theoretical efficiency of 40% is possible, with laboratory specimens thus far attaining 20% levels and mass-produced cells 10-18%. Series and parallel connections of cells in modules to yield specific outputs are considered, together with nominal construction considerations to make the modules resistant to environmental corrosion and the effects of shading from other modules. Ribbon, crystal ingot, and thin film production technologies are discussed, with mention made of the fact that crystalline cells are more expensive, yet have the highest efficiencies, while thin films offer low-cost, mass-production advantages although only 5% efficiencies have been attained with production-scale thin films. Finally, solar cell materials, including Si, CdS, InP, GaAs, and CdTe are investigated, along with prospects for indigenous solar cell production facilities in various countries.

Hill, R.

256

Electrical overstress failure in silicon solar cells  

SciTech Connect

A solar-cell electrical-overstress-failure model and the results of experimental measurements of threshold pulsed failure currents on four types of silicon solar cells are presented. The transient EMP field surrounding a lightning stroke has been identified as a potential threat to a photovoltaic array, yet failure analysis of solar cells in a pulsed environment had not previously been reported. Failure in the low-resistivity concentrator cells at pulse widths between 1 ..mu..s and 1 ms occurred initially in the junction. Finger damage in the form of silver melting occurs at currents only slightly greater than that required for junction damage. The result of reverse-bias transient-overstress tests on high-resistivity (10 ..cap omega..cm) cells demonstrated that the predominant failure mode was due to edge currents. These flat-plate cells failed at currents of only 4 to 20 A, which is one or two orders of magnitude below the model predictions. It thus appears that high-resistivity flat-plate cells are quite vulnerable to electrical overstress which could be produced by a variety of mechanisms.

Pease, R.L.; Barnum, J.R.; van Lint, V.A.J.; Vulliet, W.V.; Wrobel, T.F.

1982-11-01

257

[Light-induced changes in quantum yields of the photochemical cycle of conversion of bacteriorhodopsin and transmembrane proton transfer in cells of Halobacterium halobium].  

PubMed

It was found that the rate of proton efflux from the cells, vH+, and the turnover number of bacteriorhodopsin photoconversion cycle per second, vM, are gradually decreased during continuous illumination of Halobacterium halobium with orange light (550-650 nm, 10(3) W/m2). The steady-state value of vH+ after 3 min of illumination is 3 times lower than vH+ at the 1st second of illumination. At the same time the concentration of the photochemical cycle intermediate, M412, the quantum yield of its formation, phi M, and the quantum efficiency of proton efflux, phi H+, are decreased (phi M and phi H+ up to 3-4-fold), whereas the concentration of the initial form of bacteriorhodopsin, BR570, and lifetime of M412, tau, are increased. These light-induced effects are abolished by uncoupler, carbonylcyanide m-chlorophenylhydrazone (CCCP) and are enhanced by the phosphorylation inhibitor, N,N'-dicyclohexylcarbodiimide (DCCD). This suggests that the observed changes of M412 and BR570 concentrations, tau, VH+, VM, phi M and phi H+ are due to the light-induced changes in the transmembrane electric potential, delta psi, and in pH inside and outside the cell, which control the photochemical cycle reactions. The decrease of phi M and phi H+ is discussed on the basis of an earlier proposed scheme of the branched photochemical cycle. It is assumed that the back reactions of the cycle (shunts) not coupled with the transmembrane proton translocation, e.g. conversion of L550 (P550) into BR570 without M412 formation, etc., become more probably at high values of the proton electrochemical potential gradient. PMID:7115823

Dubrovski?, V T; Balashov, S P; Sineshchekov, O A; Chekulaeva, L N; Litvin, F F

1982-07-01

258

Bandgap tuning of multiferroic oxide solar cells  

NASA Astrophysics Data System (ADS)

Multiferroic films are increasingly being studied for applications in solar energy conversion because of their efficient ferroelectric polarization-driven carrier separation and above-bandgap generated photovoltages, which in principle can lead to energy conversion efficiencies beyond the maximum value (?34%) reported in traditional silicon-based bipolar heterojunction solar cells. However, the efficiency reported so far is still too low (<2%) to be considered for commercialization. Here, we demonstrate a new approach to effectively tune the bandgap of double perovskite multiferroic oxides by engineering the cationic ordering for the case of Bi2FeCrO6. Using this approach, we report a power conversion efficiency of 8.1% under AM 1.5?G irradiation (100?mW?cm?2) for Bi2FeCrO6 thin-film solar cells in a multilayer configuration.

Nechache, R.; Harnagea, C.; Li, S.; Cardenas, L.; Huang, W.; Chakrabartty, J.; Rosei, F.

2015-01-01

259

High-performance silicon nanohole solar cells.  

PubMed

We demonstrate Si nanohole arrays as a superior sunlight-absorbing nanostructure for photovoltaic solar cell applications. Under 1 sun AM1.5G illumination, a Si nanohole solar cell with p-n junctions via P diffusion exhibited a open-circuit voltage of 566.6 mV, a short-circuit current density of 32.2 mA/cm(2), and a remarkable power conversion efficiency of 9.51%, which is higher than that of its counterparts based on Si nanowires, planar Si, and pyramid-textured Si. The nanohole array geometry presents a novel and viable method fo cost-efficient solar energy conversion. PMID:20426468

Peng, Kui-Qing; Wang, Xin; Li, Li; Wu, Xiao-Ling; Lee, Shuit-Tong

2010-05-26

260

Photovoltaic nanocrystal scintillators hybridized on Si solar cells  

E-print Network

Photovoltaic nanocrystal scintillators hybridized on Si solar cells for enhanced conversion@bilkent.edu.tr Abstract: We propose and demonstrate semiconductor nanocrystal based photovoltaic scintillators integrated on solar cells to enhance photovoltaic device parameters including spectral responsivity, open circuit

Demir, Hilmi Volkan

261

High temperature investigations of crystalline silicon solar cell materials  

E-print Network

Crystalline silicon solar cells are a promising candidate to provide a sustainable, clean energy source for the future. In order to bring about widespread adoption of solar cells, much work is needed to reduce their cost. ...

Hudelson, George David Stephen, III

2009-01-01

262

Semitransparent ultrathin CdTe solar cells Semitransparent ultrathin CdTe solar cells and durabilityand durability  

E-print Network

: · Window area >> rooftop space · PV windows produce power and reduce Solar Heat Gain (SHG). Generate power bl d ) (very poor aesthetics) (good efficiency but venetian blind appearance, expensive) Solar RoofSemitransparent ultrathin CdTe solar cells Semitransparent ultrathin CdTe solar cells

Rollins, Andrew M.

263

Reverse bias degradation in dye solar cells  

NASA Astrophysics Data System (ADS)

A prolonged reverse bias (RB) stress forcing a short-circuit current through a dye solar cell, corresponding to the harshest test a shadowed cell may experience in real conditions, can cause the RB operating voltage VRB to drift with time, initially slowly but accelerating for VRB < (-1.65 0.15)V when gas bubbles, identified as H2 (gas chromatography), are produced inside the cell, leading to breakdown. A close connection between VRB, cell performance, and stability was established. Contributions to RB degradation include triiodide depletion and impurities, in particular water. Acting upon these components and setting up protection strategies is important for delivering long-lasting modules.

Mastroianni, Simone; Lanuti, Alessandro; Brown, Thomas M.; Argazzi, Roberto; Caramori, Stefano; Reale, Andrea; Di Carlo, Aldo

2012-09-01

264

Amorphous Siliconbased Solar Cells Xunming Deng1  

E-print Network

light when excited by the current. Amorphous silicon was deposited as a thin film on substrates inserted was xerography [1, 2], which exploited the photoconductivity of noncrystalline selenium. As do all semicon efficient solar cells using a silane glow discharge to deposit films. In 1976, he and Christopher Wronski

Schiff, Eric A.

265

Improved method of solar-cell assembly  

NASA Technical Reports Server (NTRS)

Method bonds solar-cell modules between rigid or flexible base and plastic protective cover. Method relies on using one of several commercially-available, transparent, silicone adhesives as bonding agent. Should it ever be necessary to repair or replace some part of assembly, it may be possible to remove cover without destroying package since adhesive remains flexible.

Broder, J. D.; Forestieri, A. F.; Mandelkorn, J.

1979-01-01

266

Basic mechanisms governing solar-cell efficiency  

NASA Technical Reports Server (NTRS)

The efficiency of a solar cell depends on the material parameters appearing in the set of differential equations that describe the transport, recombination, and generation of electrons and holes. This paper describes the many basic mechanisms occurring in semiconductors that can control these material parameters.

Lindholm, F. A.; Neugroschel, A.; Sah, C. T.

1976-01-01

267

Method of fabricating a solar cell  

DOEpatents

Methods of fabricating solar cells are described. A porous layer may be formed on a surface of a substrate, the porous layer including a plurality of particles and a plurality of voids. A solution may be dispensed into one or more regions of the porous layer to provide a patterned composite layer. The substrate may then be heated.

Pass, Thomas; Rogers, Robert

2014-02-25

268

Phthalocyanine Blends Improve Bulk Heterojunction Solar Cells  

PubMed Central

A core phthalocyanine platform allows engineering the solubility properties the band gap; shifting the maximum absorption toward the red. A simple method to increase the efficiency of heterojunction solar cells uses a self-organized blend of the phthalocyanine chromophores fabricated by solution processing. PMID:20136126

Varotto, Alessandro; Nam, Chang-Yong; Radivojevic, Ivana; Tom, Joao; Cavaleiro, Jos A.S.; Black, Charles T.; Drain, Charles Michael

2010-01-01

269

Metal electrode for amorphous silicon solar cells  

DOEpatents

An amorphous silicon solar cell having an N-type region wherein the contact to the N-type region is composed of a material having a work function of about 3.7 electron volts or less. Suitable materials include strontium, barium and magnesium and rare earth metals such as gadolinium and yttrium.

Williams, Richard (Princeton, NJ)

1983-01-01

270

Tandem junction amorphous silicon solar cells  

DOEpatents

An amorphous silicon solar cell has an active body with two or a series of layers of hydrogenated amorphous silicon arranged in a tandem stacked configuration with one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon arranged in tandem configuration can have the same bandgap or differing bandgaps.

Hanak, Joseph J. (Lawrenceville, NJ)

1981-01-01

271

Optimum operating conditions of a solar cell panel and prediction of solar radiation in Sanaa, Yemen  

Microsoft Academic Search

Results of a study of the performance of solar cells under nominal operating conditions in Yemen are reported. The solar cell panel comprised 14 Si cells of .003 sq m surface area each, and was mounted on a rooftop with the solar radiation being measured by a pyranometer. Further monitoring was performed of the panel surface temperature, the ambient air

A. Khogali; M. R. I. Ramadan

1982-01-01

272

Intensity modulated short circuit current spectroscopy for solar cells  

Microsoft Academic Search

Understanding charge separation and transport is momentously important for the rectification of solar cell performance. To probe photo-generated carrier dynamics, we implemented intensity modulated short circuit current spectroscopy (IMSCCS) on porous Si and Cu(Inx,Ga1?x)Se2 solar cells. In this experiment, the solar cells were lightened with sinusoidally modulated monochromatic light. The photocurrent response of the solar cell as a function of

Nese Kavasoglu; A. Sertap Kavasoglu; Ozcan Birgi; Sener Oktik

2011-01-01

273

Preparing Solar Cells for Soldering  

NASA Technical Reports Server (NTRS)

Solder paste and contact ribbon dispensed in synchronism. Solder-paste dispenser operates on one cell at a time. Ribbon fed up ramps and into positioned while solder paste is applied. When ramps are moved out of way, ribbon lies down onto cell.

Hagerty, J. J.

1983-01-01

274

Plastic Schottky barrier solar cells  

DOEpatents

A photovoltaic cell structure is fabricated from an active medium including an undoped, intrinsically p-type organic semiconductor comprising polyacetylene. When a film of such material is in rectifying contact with a magnesium electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates the magnesium layer on the undoped polyacetylene film.

Waldrop, James R. (Thousand Oaks, CA); Cohen, Marshall J. (Thousand Oaks, CA)

1984-01-24

275

High efficiency crystalline silicon solar cells  

NASA Technical Reports Server (NTRS)

A review of the entire research program since its inception ten years ago is given. The initial effort focused on the effects of impurities on the efficiency of silicon solar cells to provide figures of maximum allowable impurity density for efficiencies up to about 16 to 17%. Highly accurate experimental techniques were extended to characterize the recombination properties of the residual imputities in the silicon solar cell. A numerical simulator of the solar cell was also developed, using the Circuit Technique for Semiconductor Analysis. Recent effort focused on the delineation of the material and device parameters which limited the silicon efficiency to below 20% and on an investigation of cell designs to break the 20% barrier. Designs of the cell device structure and geometry can further reduce recombination losses as well as the sensitivity and criticalness of the fabrication technology required to exceed 20%. Further research is needed on the fundamental characterization of the carrier recombination properties at the chemical impurity and physical defect centers. It is shown that only single crystalline silicon cell technology can be successful in attaining efficiencies greater than 20%.

Sah, C. Tang

1986-01-01

276

NANO REVIEW Enhancing Solar Cell Efficiencies through 1-D Nanostructures  

E-print Network

NANO REVIEW Enhancing Solar Cell Efficiencies through 1-D Nanostructures Kehan Yu ? Junhong Chen. Nanostructured materials have offered new oppor- tunities to design more efficient solar cells, particularly one-dimensional (1-D) nanomaterials for enhancing solar cell efficiencies. These 1-D nanostructures, including

Chen, Junhong

277

Questions I will answer What is a solar cell?  

E-print Network

Electrode #12;Solar cells are the main source of electricity off the electrical the whole country with electricity. J.A. Turner, Science 285 1999, p. 687. #12;Why solar cells are likely generates lots of CO2. ·Solar cells provide electricity exactly when we need it the most. #12

McGehee, Michael

278

Hybrid Silicon Nanocone-Polymer Solar Cells Sangmoo Jeong,  

E-print Network

with enhanced light absorption resulted in a power conversion efficiency above 11%. Based on our simulation solar cell.1 Conventional Si solar cells have p-n junctions inside for an efficient extraction of lightHybrid Silicon Nanocone-Polymer Solar Cells Sangmoo Jeong, Erik C. Garnett, Shuang Wang, Zongfu Yu

Cui, Yi

279

Passivation layer for steel substrate of solar cell  

NASA Technical Reports Server (NTRS)

Solar cell is fabricated on commerical sheet-steel substrate passivated with tungsten layer. Layer prevents constituents of steel from interacting with semiconductor materials in MOS thin-film solar cell. Thin plating of nickel on steel improves bonding of tungsten. Use of steel as substrate reduces materials cost of solar cell construction.

Stirn, R. J.; Yeh, Y. M.

1981-01-01

280

EELE408 Photovoltaics Lecture 16: Silicon Solar Cell Fabrication Techniques  

E-print Network

by Efficiency 22 Rear Panel before Lamination 23 Buried Contact Solar Cells · High Efficiency · Laser groved1 EELE408 Photovoltaics Lecture 16: Silicon Solar Cell Fabrication Techniques Dr. Todd J. Kaiser - Bozeman Screen Printed Solar Cells · Starting wafer is about 0.5 mm thick and 10 x 10 cm2. The wafer is p

Kaiser, Todd J.

281

Light Trapping in Solar Cells Using Resonant Nanostructures P. Spinelli  

E-print Network

Light Trapping in Solar Cells Using Resonant Nanostructures P. Spinelli #12;Summary Photovoltaics solar cell is reduced, due to incomplete absorption of light. In this thesis, we investigate new ways of enhancing light absorption in Si solar cells by using nanostructures that show resonant interaction

van Rooij, Robert

282

Determination of the solar cell panel installation angle  

Microsoft Academic Search

The output power of the solar cell panel is highly affected by the sunlight incident angle. The efficiency can be improved if the solar cell panel is properly installed with the optimum angle. The relationship between the sunlight incident angle and the sunlight radiation intensity on the solar cell panel surface is presented in this paper. Genetic algorithms with climatic

Yaow-Ming Chen; Hsu-Chin Wu

2001-01-01

283

The cooling technology of solar cells under concentrated system  

Microsoft Academic Search

Temperature control is very important to keep the efficiency of solar cells, because the open-circuit voltage of the system is obviously dropped, when the temperature is raised, so as to a decline in output power of solar cells. Especially in the concentrated system, solar cells worked several times even hundreds of times in the irradiation conditions, so the temperature will

Ye Zhangbo; Li Qifen; Zhu Qunzhi; Pan Weiguo

2009-01-01

284

Flexible thermal cycle test equipment for concentrator solar cells  

DOEpatents

A system and method for performing thermal stress testing of photovoltaic solar cells is presented. The system and method allows rapid testing of photovoltaic solar cells under controllable thermal conditions. The system and method presents a means of rapidly applying thermal stresses to one or more photovoltaic solar cells in a consistent and repeatable manner.

Hebert, Peter H. (Glendale, CA); Brandt, Randolph J. (Palmdale, CA)

2012-06-19

285

Nanocluster production for solar cell applications  

SciTech Connect

This research focuses on the fabrication and characterization of silver (Ag) and silicon (Si) nanoclusters that might be used for solar cell applications. Silver and silicon nanoclusters have been synthesized by means of dc magnetron sputtering and inert gas condensation inside an ultra-high vacuum compatible system. We have found that nanocluster size distributions can be tuned by various source parameters, such as the sputtering discharge power, flow rate of argon inert gas, and aggregation length. Quadrupole mass filter and transmission electron microscopy were used to evaluate the size distribution of Ag and Si nanoclusters. Ag nanoclusters with average size in the range of 3.68.3 nm were synthesized (herein size refers to the nanocluster diameter), whereas Si nanoclusters' average size was controlled to range between 2.9 and 7.4 nm by controlling the source parameters. This work illustrates the ability of controlling the Si and Ag nanoclusters' sizes by proper optimization of the operation conditions. By controlling nanoclusters' sizes, one can alter their surface properties to suit the need to enhance solar cell efficiency. Herein, Ag nanoclusters were deposited on commercial polycrystalline solar cells. Short circuit current (I{sub SC}), open circuit voltage (V{sub OC}), fill factor, and efficiency (?) were obtained under light source with an intensity of 30 mW/cm{sup 2}. A 22.7% enhancement in solar cell efficiency could be measured after deposition of Ag nanoclusters, which demonstrates that Ag nanoclusters generated in this work are useful to enhance solar cell efficiency.

Al Dosari, Haila M.; Ayesh, Ahmad I. [Department of Physics, United Arab Emirates University, P. O. Box 15551, Al Ain (United Arab Emirates)] [Department of Physics, United Arab Emirates University, P. O. Box 15551, Al Ain (United Arab Emirates)

2013-08-07

286

Space solar cell technology development - A perspective  

NASA Technical Reports Server (NTRS)

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.

Scott-Monck, J.

1982-01-01

287

Photochemical Escape of Oxygen from Early Mars  

E-print Network

Photochemical escape is an important process for oxygen escape from present Mars. In this work, a 1-D Monte-Carlo Model is developed to calculate escape rates of energetic oxygen atoms produced from O2+ dissociative recombination reactions (DR) under 1, 3, 10, and 20 times present solar XUV fluxes. We found that although the overall DR rates increase with solar XUV flux almost linearly, oxygen escape rate increases from 1 to 10 times present solar XUV conditions but decreases when increasing solar XUV flux further. Analysis shows that atomic species in the upper thermosphere of early Mars increases more rapidly than O2+ when increasing XUV fluxes. While the latter is the source of energetic O atoms, the former increases the collision probability and thus decreases the escape probability of energetic O. Our results suggest that photochemical escape be a less important escape mechanism than previously thought for the loss of water and/or CO2 from early Mars.

Zhao, Jinjin

2015-01-01

288

Piezoresistance and solar cell efficiency  

NASA Technical Reports Server (NTRS)

Diffusion-induced stresses in silicon are shown to result in large localized changes in the minority-carrier mobility which in turn can have a significant effect on cell output. Evidence is given that both compressive and tensile stresses can be generated in either the emitter or the base region. Tensile stresses in the base appear to be much more effective in altering cell performance than do compressive stresses. While most stress-related effects appear to degrade cell efficiency, this is not always the case. Evidence is presented showing that arsenic-induced stresses can result in emitter characteristics comparable to those found in the MINP cell without requiring a high degree of surface passivation.

Weizer, Victor G.

1987-01-01

289

NANOCOMPOSITE ENABLED SENSITIZED SOLAR CELL  

E-print Network

series and parallel resistance, may be estimated by fitting the equivalent circuitin the equivalent circuit. The series resistance arises fromseries and shunt resistance to the cell. Increasing R S , will decrease the short circuit

Phuyal, Dibya

2012-01-01

290

Prediction of solar cell performance in space  

SciTech Connect

Predicting solar array performance with a high degree of accuracy is of critical importance to the success of space missions. This calculation is influenced by a large number of variables and parameters. Consequently, the accurate prediction becomes very difficult and safety margins must be assigned because of unknown factors relating to incomplete description of the behavior of the materials and components in the solar array. This paper discusses two factors which are important in such predictions. The first is a description of the gradual deterioration of the optical transmissivity of the coverglass and its adhesive layer, using data derived from the solar cell experiment on the Naval Research Laboratory NTS-2 satellite. The magnitude of this effect is shown through the interpretation of satellite data. The second factor is temperature enhanced radiation damage which was observed during radiation experiments at low dose rates on silicon solar cells. These experiments are being carried out at the NRL Cobalt 60 facility. The observed radiation damage is shown to be strongly dependent on the temperature of the silicon cells during irradiation. The magnitude of this effect is shown in its influence on the interpretation of satellite data.

Statler, R.L.; Walker, D.M.

1982-09-01

291

Enhancing Solar Cell Efficiencies through 1-D Nanostructures  

PubMed Central

The current global energy problem can be attributed to insufficient fossil fuel supplies and excessive greenhouse gas emissions resulting from increasing fossil fuel consumption. The huge demand for clean energy potentially can be met by solar-to-electricity conversions. The large-scale use of solar energy is not occurring due to the high cost and inadequate efficiencies of existing solar cells. Nanostructured materials have offered new opportunities to design more efficient solar cells, particularly one-dimensional (1-D) nanomaterials for enhancing solar cell efficiencies. These 1-D nanostructures, including nanotubes, nanowires, and nanorods, offer significant opportunities to improve efficiencies of solar cells by facilitating photon absorption, electron transport, and electron collection; however, tremendous challenges must be conquered before the large-scale commercialization of such cells. This review specifically focuses on the use of 1-D nanostructures for enhancing solar cell efficiencies. Other nanostructured solar cells or solar cells based on bulk materials are not covered in this review. Major topics addressed include dye-sensitized solar cells, quantum-dot-sensitized solar cells, and p-n junction solar cells.

2009-01-01

292

Laser synthesized super-hydrophobic conducting carbon with broccoli-type morphology as a counter-electrode for dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode.A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode. Electronic supplementary information (ESI) available: Materials and equipment details, solar cell fabrication protocol, electrolyte spreading time measurement details, XPS spectra, electronic study, film adhesion test detailed analysis and field emission results. See DOI: 10.1039/c2nr32082g

Gokhale, Rohan; Agarkar, Shruti; Debgupta, Joyashish; Shinde, Deodatta; Lefez, Benoit; Banerjee, Abhik; Jog, Jyoti; More, Mahendra; Hannoyer, Beatrice; Ogale, Satishchandra

2012-10-01

293

Deng & Schiff, Amorphous Silicon Based Solar Cells rev. 7/30/2002, Page 1 Amorphous Silicon Based Solar Cells  

E-print Network

Deng & Schiff, Amorphous Silicon Based Solar Cells rev. 7/30/2002, Page 1 Amorphous Silicon Based Solar Cells Xunming Deng and Eric A. Schiff Table of Contents 1 Overview 3 1.1 Amorphous Silicon: The First Bipolar Amorphous Semiconductor 3 1.2 Designs for Amorphous Silicon Solar Cells: A Guided Tour 6

Deng, Xunming

294

Solar Airplanes and Regenerative Fuel Cells  

NASA Technical Reports Server (NTRS)

A solar electric aircraft with the potential to "fly forever" has captured NASA's interest, and the concept for such an aircraft was pursued under Aeronautics Environmental Research Aircraft and Sensor Technology (ERAST) project. Feasibility of this aircraft happens to depend on the successful development of solar power technologies critical to NASA's Exploration Initiatives; hence, there was widespread interest throughout NASA to bring these technologies to a flight demonstration. The most critical is an energy storage system to sustain mission power during night periods. For the solar airplane, whose flight capability is already limited by the diffuse nature of solar flux and subject to latitude and time of year constraints, the feasibility of long endurance flight depends on a storage density figure of merit better than 400-600 watt-hr per kilogram. This figure of merit is beyond the capability of present day storage technologies (other than nuclear) but may be achievable in the hydrogen-oxygen regenerative fuel cell (RFC). This potential has led NASA to undertake the practical development of a hydrogen-oxygen regenerative fuel cell, initially as solar energy storage for a high altitude UAV science platform but eventually to serve as the primary power source for NASAs lunar base and other planet surface installations. Potentially the highest storage capacity and lowest weight of any non-nuclear device, a flight-weight RFC aboard a solar-electric aircraft that is flown continuously through several successive day-night cycles will provide the most convincing demonstration that this technology's widespread potential has been realized. In 1998 NASA began development of a closed cycle hydrogen oxygen PEM RFC under the Aeronautics Environmental Research Aircraft and Sensor Technology (ERAST) project and continued its development, originally for a solar electric airplane flight, through FY2005 under the Low Emissions Alternative Power (LEAP) project. Construction of the closed loop system began in 2002 at the NASA Glenn Research Center in Cleveland, Ohio. System checkout was completed, and testing began, in July of 2003. The initial test sequences were done with only a fuel cell or electrolyzer in the test rig. Those tests were used to verify the test apparatus, procedures, and software. The first complete cycles of the fully closed loop, regenerative fuel cell system were successfully completed in the following September. Following some hardware upgrades to increase reactant recirculation flow, the test rig was operated at full power in December 2003 and again in January 2004. In March 2004 a newer generation of fuel cell and electrolyzer stacks was substituted for the original hardware and these stacks were successfully tested at full power under cyclic operation in June of 2004.

Bents, David J.

2007-01-01

295

Advanced high efficiency wraparound contact solar cell  

NASA Technical Reports Server (NTRS)

A significant advancement in the development of thin high efficiency wraparound contact silicon solar cells has been made by coupling space and terrestrial processing procedures. Although this new method for fabricating cells has not been completely reduced to practice, some of the initial cells have delivered over 20 mW/sq cm when tested at 25 C under AMO intensity. This approach not only yields high efficiency devices, but shows promise of allowing complete freedom of choice in both the location and size of the wraparound contact pad area.

Scott-Monck, J. A.; Uno, F. M.; Thornhill, J. W.

1977-01-01

296

Advanced high efficiency wraparound contact solar cell  

NASA Technical Reports Server (NTRS)

A significant advancement in the development of thin high efficiency wraparound contact silicon solar cells has been made by coupling space and terrestrial processing procedures. Although this new method for fabricating cells has not been completely reduced to practice, some of the initial cells have delivered over 20 mW/sq cm when tested at 25 C under AMO intensity. This approach not only yields high efficiency devices, but shows promise of allowing complete freedom of choice in both the location and size of the wraparound contact pad area

Scott-Monck, J. A.; Uno, F. M.; Thornhill, J. W.

1977-01-01

297

Gallium Arsenide solar cell radiation damage experiment  

NASA Technical Reports Server (NTRS)

Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

1991-01-01

298

Inkjet Printing of Titanium Dioxide Photoanodes for Dye Sensitized Solar Cells.  

E-print Network

??Dye Sensitized Solar Cells (DSSC) offer advantages over semiconductor solar cells including lower costs and relaxed material purity requirements. However, DSSC solar energy conversion efficiencies (more)

Johnson, Jeffrey Corbet

2013-01-01

299

Semi-transparent inverted organic solar cells  

NASA Astrophysics Data System (ADS)

We will present efficient semi-transparent bulk-heterojunction [regioregular of poly(3-hexylthiophene): (6,6)-phenyl C61 butyric acid methyl ester] solar cells with an inverted device architecture. Highly transparent ZnO and TiO2 films prepared by Atomic Layer Deposition are used as cathode interlayers on top of ITO. The topanode consists of a RF-sputtered ITO layer. To avoid damage due to the plasma deposition of this layer, a sputtering buffer layer of MoO3 is used as protection. This concept allows for devices with a transmissivity higher than 60 % for wavelengths 650 nm. The thickness of the MoO3 buffer has been varied in order to study its effect on the electrical properties of the solar cell and its ability to prevent possible damage to the organic active layers upon ITO deposition. Without this buffer or for thin buffers it has been found that device performance is very poor concerning the leakage current, the fill factor, the short circuit current and the power conversion efficiencies. As a reference inverted solar cells with a metal electrode (Al) instead of the ITO-top contact are used. The variation between the PCE of top versus conventional illumination of the semi-transparent cells was also examined and will be interpreted in view of the results of the optical simulation of the dielectric device stack with and without reflection top electrode. Power conversion efficiencies of 2-3 % for the opaque inverted solar cells and 1.5-2.5 % for the semi-transparent devices were obtained under an AM1.5G illumination.

Schmidt, H.; Winkler, T.; Tilgner, M.; Flgge, H.; Schmale, S.; Blow, T.; Meyer, J.; Johannes, H.-H.; Riedl, T.; Kowalsky, W.

2009-08-01

300

Recent advances in sensitized mesoscopic solar cells.  

PubMed

Perhaps the largest challenge for our global society is to find ways to replace the slowly but inevitably vanishing fossil fuel supplies by renewable resources and, at the same time, avoid negative effects from the current energy system on climate, environment, and health. The quality of human life to a large degree depends upon the availability of clean energy sources. The worldwide power consumption is expected to double in the next 3 decades because of the increase in world population and the rising demand of energy in the developing countries. This implies enhanced depletion of fossil fuel reserves, leading to further aggravation of the environmental pollution. As a consequence of dwindling resources, a huge power supply gap of 14 terawatts is expected to open up by year 2050 equaling today's entire consumption, thus threatening to create a planetary emergency of gigantic dimensions. Solar energy is expected to play a crucial role as a future energy source. The sun provides about 120,000 terawatts to the earth's surface, which amounts to 6000 times the present rate of the world's energy consumption. However, capturing solar energy and converting it to electricity or chemical fuels, such as hydrogen, at low cost and using abundantly available raw materials remains a huge challenge. Chemistry is expected to make pivotal contributions to identify environmentally friendly solutions to this energy problem. One area of great promise is that of solar converters generally referred to as "organic photovoltaic cells" (OPV) that employ organic constituents for light harvesting or charge carrier transport. While this field is still in its infancy, it is receiving enormous research attention, with the number of publications growing exponentially over the past decade. The advantage of this new generation of solar cells is that they can be produced at low cost, i.e., potentially less than 1 U.S. $/peak watt. Some but not all OPV embodiments can avoid the expensive and energy-intensive high vacuum and materials purification steps that are currently employed in the fabrication of all other thin-film solar cells. Organic materials are abundantly available, so that the technology can be scaled up to the terawatt scale without running into feedstock supply problems. This gives organic-based solar cells an advantage over the two major competing thin-film photovoltaic devices, i.e., CdTe and CuIn(As)Se, which use highly toxic materials of low natural abundance. However, a drawback of the current embodiment of OPV cells is that their efficiency is significantly lower than that for single and multicrystalline silicon as well as CdTe and CuIn(As)Se cells. Also, polymer-based OPV cells are very sensitive to water and oxygen and, hence, need to be carefully sealed to avoid rapid degradation. The research discussed within the framework of this Account aims at identifying and providing solutions to the efficiency problems that the OPV field is still facing. The discussion focuses on mesoscopic solar cells, in particular, dye-sensitized solar cells (DSCs), which have been developed in our laboratory and remain the focus of our investigations. The efficiency problem is being tackled using molecular science and nanotechnology. The sensitizer constitutes the heart of the DSC, using sunlight to pump electrons from a lower to a higher energy level, generating in this fashion an electric potential difference, which can exploited to produce electric work. Currently, there is a quest for sensitizers that achieve effective harnessing of the red and near-IR part of sunlight, converting these photons to electricity better than the currently used generation of dyes. Progress in this area has been significant over the past few years, resulting in a boost in the conversion efficiency of the DSC that will be reviewed. PMID:19715294

Grtzel, Michael

2009-11-17

301

Recent progress in Si thin film technology for solar cells  

NASA Astrophysics Data System (ADS)

Progress in Si thin film technology 'specifically amorphous Si (a-Si) and polycrystalline Si (poly-Si) thin film' for solar cells is summarized here from fabrication method, material, and structural viewpoints. In addition to a-Si, primary results on poly-Si thin film research are discussed. Various applications for a-Si solar cells are mentioned, and consumer applications and a-Si solar cell photovoltaic systems are introduced. New product developments include see-through solar cells, solar cell roofing tiles, and ultra-light flexible solar cells. As for new systems, air conditioning equipment powered by solar cells is described. Looking to the future, the proposed GENESIS project is discussed.

Kuwano, Yukinori; Nakano, Shoichi; Tsuda, Shinya

1991-11-01

302

Gallium arsenide solar cell radiation damage study  

NASA Technical Reports Server (NTRS)

A thorough analysis has been made of electron- and proton- damaged GaAs solar cells suitable for use in space. It is found that, although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I-V analysis model shows that electrons damage the bulk of the cell and its currents relatively more, while protons damage the junction of the cell and its voltages more. It is suggested that multiple defects due to protons in a strong field region such as a p/n junction cause the greater degradation in cell voltage, whereas the individual point defects in the quasi-neutral minority-carrier-diffusion regions due to electrons cause the greater degradation in cell current and spectral response.

Maurer, R. H.; Herbert, G. A.; Kinnison, J. D.; Meulenberg, A.

1989-01-01

303

Thin-film polycrystalline silicon solar cells  

NASA Astrophysics Data System (ADS)

Thirty-four new solar cells were fabricated on Wacker Sislo substrates and the AM-1 parameters were measured. A detailed comparison was made between the measurement of minority carrier diffusion length by the OE method and the penetrating light laser scan grain boundary photoresponse linewidth method. The laser scan method has more experimental uncertainty and agrees within 10 to 50% with the QE method. It allows determination of L over a large area. Atomic hydrogen passivation studies continued on Wacker material by three techniques. A method of determining surface recombination velocity, s, from laser scan data was developed. No change in s in completed solar cells after H-plasma treatment was observed within experimental error. H-passivation of bare silicon cars as measured by the new laser scan photoconductivity technique showed very large effects.

Funghnan, B. W.; Blanc, J.; Phillips, W.; Redfield, D.

1980-08-01

304

Green-solvent-processed molecular solar cells.  

PubMed

High-efficiency bulk heterojunction (BHJ) organic solar cells with power conversion efficiencies of more than 5?% can be fabricated using the green solvent 2-MeTHF. The active layers comprise a blend of a molecular semiconductor donor with intermediate dimensions (X2) and the soluble fullerene derivative [6,6]-phenyl-C61 -butyricacidoctylester (PC61 BC8 ). A switch of the processing solvent from chloroform to 2-MeTHF leads to no negative impacts on the morphology and charge-transport properties of optimally performing BHJ films. Examinations by absorption spectroscopy, atomic force microscopy, and grazing incidence wide-angle X-ray scattering reveal no significant modification of morphology. These results show that green solvents can be excellent alternatives for large-area printing of high-performance organic photovoltaics (OPVs) and thus open new opportunities for sustainable mass production of organic solar cells and other optoelectronic devices. PMID:25389005

Chen, Xiaofen; Liu, Xiaofeng; Burgers, Mark A; Huang, Ye; Bazan, Guillermo C

2014-12-22

305

Development of GaAs solar cells  

NASA Technical Reports Server (NTRS)

Solar cells and mesa diodes were fabricated by the implantation of zinc or beryllium ions into n-type gallium arsenide. Annealing temperatures above 750 C (zinc) or 650 C (beryllium) were found to produce 50% to 100% activation of the implanted ions. Junction depths of about 0.4 micron were produced by 600 keV zinc implants or 70 keV beryllium implants. P-layer sheet resistance was about 150 ohms for 2 x 10 to the 15th power cm/2 zinc or 1 x 10 to the 15th power cm/2 beryllium implants. This is sufficiently low for efficient solar cell fabrication. Contacting procedures were improved to yield reproducibly adherent, low resistance front and back contacts.

1972-01-01

306

Advanced Solar Cell Testing and Characterization  

NASA Technical Reports Server (NTRS)

The topic for this workshop stems from an ongoing effort by the photovoltaic community and U.S. government to address issues and recent problems associated with solar cells and arrays experienced by a number of different space systems. In April 2003, a workshop session was held at the Aerospace Space Power Workshop to discuss an effort by the Air Force to update and standardize solar cell and array qualification test procedures in an effort to ameliorate some of these problems. The organizers of that workshop session thought it was important to continue these discussions and present this information to the entire photovoltaic community. Thus, it was decided to include this topic as a workshop at the following SPRAT conference.

Bailey, Sheila; Curtis, Henry; Piszczor, Michael

2005-01-01

307

Compensated amorphous-silicon solar cell  

DOEpatents

An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the elecrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF/sub 3/ doped intrinsic layer.

Devaud, G.

1982-06-21

308

Solar cells: perovskite solar cells: from materials to devices (small 1/2015).  

PubMed

Since the first report in 2012 of a long-term durable solid-state perovskite solar cell, one with a power conversion efficiency (PCE) of 19.3% has been demonstrated, and a certified PCE of 17.9% was shown this year. The high-efficiency and cost-effective materials and processes for perovskite solar cells make them economically viable for commercialization. Moreover, their mechanical functionalities will increase their economic viability. These cells are discussed by H. S. Jung and N.-G. Park on page 10. PMID:25558048

Jung, Hyun Suk; Park, Nam-Gyu

2015-01-01

309

Cd free buffer layers for solar cells  

Microsoft Academic Search

CdS layers obtained by chemical bath deposition (CBD) are usually used as buffer layer in chalcogenide based thin film solar cells. However, if good results are obtained, cadmium is toxic for the environment while the break of the physical vapour deposition (PVD) cycle, needed for CBD-CdS, constitutes a bottleneck in the process. Therefore many attempts are under way, all over

J. C. Bernede; M. Zoaeter; S. Marsillak; N. Barreauk; C. Oukld El Moctark; K. Benchouk; A. Khelil

2000-01-01

310

Organic p -i- n solar cells  

Microsoft Academic Search

We introduce a p-i- n-type heterojunction architecture for organic solar cells where the active region is sandwiched between two doped wide-gap layers. The term p-i- n means here a layer sequence in the form p-doped layer, intrinsic layer and n-doped layer. The doping is realized by controlled co-evaporation using organic dopants and leads to conductivities of 10 -4 to 10

B. Maennig; J. Drechsel; D. Gebeyehu; P. Simon; F. Kozlowski; A. Werner; F. Li; S. Grundmann; S. Sonntag; M. Koch; K. Leo; M. Pfeiffer; H. Hoppe; D. Meissner; N. S. Sariciftci; I. Riedel; V. Dyakonov; J. Parisi

2004-01-01

311

High efficiency silicon solar cell review  

NASA Technical Reports Server (NTRS)

An overview is presented of the current research and development efforts to improve the performance of the silicon solar cell. The 24 papers presented reviewed experimental and analytic modeling work which emphasizes the improvment of conversion efficiency and the reduction of manufacturing costs. A summary is given of the round-table discussion, in which the near- and far-term directions of future efficiency improvements were discussed.

Godlewski, M. P. (editor)

1975-01-01

312

Dip-Coating Fabrication of Solar Cells  

NASA Technical Reports Server (NTRS)

Inexpensive silicon solar cells made by simple dip technique. Cooling shoes direct flow of helium on graphite-coated ceramic substrate to solidify film of liquid silicon on graphite surface as substrate is withdrawn from molten silicon. After heaters control cooling of film and substrate to prevent cracking. Gas jets exit at points about 10 mm from substrate surfaces and 6 to 10 mm above melt surface.

Koepke, B.; Suave, D.

1982-01-01

313

Marine environmental damage effects of solar cell panel  

Microsoft Academic Search

Solar cell is one of the crucial components in photovoltaic systems. At present, substrate crystalline silicon solar cells with clear cover glasses are widely used in photovoltaic systems. The solar panels are made of semiconducting materials including mono crystalline silicon, polycrystalline silicon and gallium arsenide (GaAs). The high transmittance glass cover is pressed together with the panel through silicone rubber,

Chengqing Yuan; Conglin Dong; Liangliang Zhao; Xinping Yan

2010-01-01

314

Multi-Exciton Generation in Nanostructured Solar Cells  

E-print Network

Multi-Exciton Generation in Nanostructured Solar Cells 1 G.T. Zimanyi UC Davis The energy is challenging, philosophically satisfying and fun #12;Multi-Exciton Generation in Nanostructured Solar Cells 2 mode 4. politically safest, conflict-free 5. non-man-made price volatility is minimal #12;The Solar

315

Device simulation of intermediate band solar cells  

NASA Astrophysics Data System (ADS)

To realize high efficiency solar cells, new concepts beyond the Shockley-Queisser limit are widely investigated. The intermediate band solar cell (IBSC) is one of the candidate concepts. From the importance of device physics, we have developed a device simulator for IBSCs. For device simulation of IBSC, the Poisson equation, carrier continuity equations of electrons in the conduction band (CB) and the valance band (VB) and balanced equation of IB state electrons must be solved self-consistently. The simulation methods can clarify the intrinsic device behavior of IBSCs which cannot be investigated by the detailed balance model. For example, by the existence of electrons trapped in IB states, electrostatic potential along the depth direction of the solar cells is strongly modified from the equilibrium under illumination of sunlight. This potential change is strongly related to its absorption property of sunlight. And the doping to IB region can enhance short circuit current density via IB states. Under larger concentration, this doping effect is decreased by the photofilling effects in the radiative limit. Absorption coefficients of each band-to-band transition are decided by the semiconductor materials and fundamental physics. These limitations make the different spectra and values from ideal treatments and decide the maximum efficiency of the IBSC. In this work, we present the fundamental properties and suggestions to approach the high efficiency IBSC operations as a device.

Yoshida, K.; Okada, Y.; Sano, N.

2012-02-01

316

Machine vision for solar cell characterization  

NASA Astrophysics Data System (ADS)

An in-line, non-destructive process is being developed for characterizing polycrystalline thin-film and other large area electronic devices using computer vision based imaging of the manufacturing and inspection steps during the device fabrication process. This process is being applied specifically to Cadmium Telluride/Cadmium Sulfide (CdTe/CdS) thin film, polycrystalline solar cells. Our process involves the acquisition of reflective, transmission and electroluminescence (EL) intensity images for each device. The EL intensity images have been processed by use of a modified median cut segmentation. The processed images reveal different gray level regions corresponding to different intensities of EL originating from radiative recombination events occurring within a biased solar cell. Higher efficiency devices show a more uniform intensity distribution in contrast with lower efficiency devices. The uniform intensity regions are made up of gray level intensity values found near the mean of the histogram distribution these are identified as regions of good device performance and are attributed to better material quality and processing. Low intensity regions indicate either material defects or errors in processing. This novel characterization process and analysis are providing new insights into the causes of poor performance in CdTe-based solar cells.

Ordaz, Miguel A.; Lush, Gregory B.

2000-03-01

317

Low-Cost Photovoltaics: Luminescent Solar Concentrators And Colloidal Quantum Dot Solar Cells  

E-print Network

solar concentrator with 7.1% power conversion efficiency,power conversion efficiency = incident solar power/convertedsolar concentrator (LSC) windows with front-facing photovoltaic (PV) cells were built and their gain and power efficiency

Leow, Shin Woei

2014-01-01

318

Photocurrent images of amorphous-silicon solar-cell modules  

NASA Technical Reports Server (NTRS)

Results obtained in applying the unique characteristics of the solar cell laser scanner to investigate the defects and quality of amorphous silicon cells are presented. It is concluded that solar cell laser scanners can be effectively used to nondestructively test not only active defects but also the cell quality and integrity of electrical contacts.

Kim, Q.; Shumka, A.; Trask, J.

1985-01-01

319

Measurement and Characterization of Concentrator Solar Cells II  

NASA Technical Reports Server (NTRS)

Concentrator solar cells are continuing to get more consideration for use in power systems. This interest is because concentrator systems can have a net lower cost per watt in solar cell materials plus ongoing improvements in sun-tracking technology. Quantitatively measuring the efficiency of solar cells under concentration is difficult. Traditionally, the light concentration on solar cells has been determined by using a ratio of the measured solar cell s short circuit current to that at one sun, this assumes that current changes proportionally with light intensity. This works well with low to moderate (<20 suns) concentration levels on "well-behaved" linear cells but does not apply when cells respond superlinearly, current increases faster than intensity, or sublinearly, current increases more slowly than intensity. This paper continues work on using view factors to determine the concentration level and linearity of the solar cell with mathematical view factor analysis and experimental results [1].

Scheiman, Dave; Sater, Bernard L.; Chubb, Donald; Jenkins, Phillip; Snyder, Dave

2005-01-01

320

Measurement and characterization of triple junction solar cells using a close matched multizone solar simulator  

Microsoft Academic Search

The photovoltaic characterization of triple-junction InGaP2\\/GaAs\\/Ge solar cells is presented. Measurements made using a single light source solar simulator are compared with other measurements made using a multi-light source solar simulator that provides a close match to the air mass zero (AM0) solar spectrum. The output spectrum of the solar simulators has been measured, and two methods for calibrating the

Jeffrey H. Warner; Robert J. Walters; Scott R. Messenger; Justin R. Lorentzen; Geoffrey P. Summers; Hector L. Cotal; Nassar H. Karam

2004-01-01

321

Laser-assisted solar cell metallization processing  

NASA Astrophysics Data System (ADS)

A new lens was installed in the laser; the laser power was lowered and solar cells were made at different power levels. The concentration of the silver neodecanoate solution was changed to reduce linewidth. A cell fabrication run was completed using low-resistivity float-zone silicon. Experiments were initiated to investigate the use of titanium organometallic film, which not only forms an AR coating with a 400(0)C hard bake, but may also help in bypassing front-metal evaporation because of high-reactivity of Ti with silicon. Progress in these areas is discussed.

Rohatgi, A.; McMullin, P. G.; Palaschak, P. A.

1985-07-01

322

Inversion layer solar cell fabrication and evaluation  

NASA Technical Reports Server (NTRS)

Inversion layer solar cells have been fabricated by etching through the diffused layer on p-type silicon wafers in a comb-like contact pattern. The charge separation comes from an induced p-n junction at the surface. This inverted surface is caused by a layer of transparent material applied to the surface that either contains free positive ions or that creates donor states at the interface. Cells have increased from 3 ma Isc to 100 ma by application of sodium silicate. The action is unstable, however, and decays with time.

Call, R. L.

1974-01-01

323

V-grooved silicon solar cells  

NASA Technical Reports Server (NTRS)

Silicon solar cells with macroscopic V-shaped grooves and microscopically texturized surfaces were made by preferential etching techniques. Various conditions for potassium hydroxide and hydrazine hydrate etching were investigated. Optical reflection losses from these surface were reduced. The reduced reflection occurred at all wavelengths and resulted in improved short circuit current and spectral response. Improved collection efficiency is also expected from this structure due to generation of carriers closer to the cell junction. Microscopic point measurements of collected current using a scanning electron microscope showed that current collected at the peaks of the texturized surface were only 80 percent of those collected in the valleys.

Baraona, C. R.; Brandhorst, H. W., Jr.

1975-01-01

324

V-grooved silicon solar cells  

NASA Technical Reports Server (NTRS)

Silicon solar cells with macroscopic V-shaped grooves and microscopically texturized surfaces have been made by preferential etching techniques. Various conditions for potassium hydroxide and hydrazine hydrate etching were investigated. Optical reflection losses from these surface were reduced. The reduced reflection occurred at all wavelengths and resulted in improved short circuit current and spectral response. Improved collection efficiency is also expected from this structure due to generation of carriers closer to the cell junction. Microscopic point measurements of collected current using a scanning electron microscope showed that current collected at the peaks of the texturized surface were only 80% of those collected in the valleys.

Baraona, C. R.; Brandhorst, H. W.

1975-01-01

325

Epitaxial solar-cell fabrication, phase 2  

NASA Technical Reports Server (NTRS)

Dichlorosilane (SiH2Cl2) was used as the silicon source material in all of the epitaxial growths. Both n/p/p(+) and p/n/n(+) structures were studied. Correlations were made between the measured profiles and the solar cell parameters, especially cell open-circuit voltage. It was found that in order to obtain consistently high open-circuit voltage, the epitaxial techniques used to grow the surface layer must be altered to obtain very abrupt doping profiles in the vicinity of the junction. With these techniques, it was possible to grow reproducibly both p/n/n(+) and n/p/p(+) solar cell structures having open-circuit voltages in the 610- to 630-mV range, with fill-factors in excess of 0.80 and AM-1 efficiencies of about 13%. Combinations and comparisons of epitaxial and diffused surface layers were also made. Using such surface layers, we found that the blue response of epitaxial cells could be improved, resulting in AM-1 short-circuit current densities of about 30 mA/cm sq. The best cells fabricated in this manner had AM-1 efficiency of 14.1%.

Daiello, R. V.; Robinson, P. H.; Kressel, H.

1977-01-01

326

The STRV-1 A & B solar cell experiments  

Microsoft Academic Search

This paper describes the solar cell experiments which are due to fly on the Defence Research Agency STRV-1A and 1B satellites. The experiment is comprised of the technology demonstration of advanced GaAs solar panels and the I-V measurement of 47 individual solar cells. The panels are using cells from 5 different manufacturers in Europe and the USA. The individual cells

C. Goodbody; N. Monekosso

1993-01-01

327

Transparent antennas for solar cell integration  

NASA Astrophysics Data System (ADS)

Transparent patch antennas are microstrip patch antennas that have a certain level of optical transparency. Highly transparent patch antennas are potentially suitable for integration with solar panels of small satellites, which are becoming increasingly important in space exploration. Traditional patch antennas employed on small satellites compete with solar cells for surface area. However, a transparent patch antenna can be placed directly on top of solar cells and resolve the issue of competing for limited surface real estate. For such an integration, a high optical transparency of the patch antenna is required from the solar cells' point of view. On the other hand, the antenna should possess at least acceptable radiation properties at the same time. This dissertation focuses on some of the most important concerns from the perspective of small satellite applications. For example, an optimization method to simultaneously improve both optical transparency and radiation efficiency of the antenna is studied. Active integrated antenna design method is extended to meshed patch applications in an attempt to improve the overall power efficiency of the front end communication subsystem. As is well known, circular polarization is immune from Faraday rotation effect in the ionosphere and thus can avoid a 3-dB loss in geo-satellite communication. Therefore, this research also aims to present design methods for circularly polarized meshed patch antennas. Moreover, a meshed patch antenna capable of supporting a high communication data rate is investigated. Lastly, other types of transparent patch antennas are also analyzed and compared to meshed patches. In summary, many properties of transparent patch antennas are examined in order to meet different design requirements.

Yasin, Tursunjan

328

Defect behavior of polycrystalline solar cell silicon  

SciTech Connect

The major objective of this study, conducted from October 1988 to September 1991, was to gain an understanding of the behavior of impurities in polycrystalline silicon and the influence of these impurities on solar cell efficiency. The authors studied edge-defined film-fed growth (EFG) and cast poly-Si materials and solar cells. With EFG Si they concentrated on chromium-doped materials and cells to determine the role of Cr on solar cell performance. Cast poly-Si samples were not deliberately contaminated. Samples were characterized by cell efficiency, current-voltage, deep-level transient spectroscopy (DLTS), surface photovoltage (SPV), open-circuit voltage decay, secondary ion mass spectrometry, and Fourier transform infrared spectroscopy measurements. They find that Cr forms Cr-B pairs with boron at room temperature and these pairs dissociate into Cr{sub i}{sup +} and B{sup {minus}} during anneals at 210{degrees}C for 10 min. Following the anneal, Cr-B pairs reform at room temperature with a time constant of 230 h. Chromium forms CrSi{sub 2} precipitates in heavily contaminated regions and they find evidence of CrSi{sub 2} gettering, but a lack of chromium segregation or precipitation to grain boundaries and dislocations. Cr-B pairs have well defined DLTS peaks. However, DLTS spectra of other defects are not well defined, giving broad peaks indicative of defects with a range of energy levels in the band gap. In some high-stress, low-efficiency cast poly-Si they detect SiC precipitates, but not in low-stress, high-efficiency samples. SPV measurements result in nonlinear SPV curves in some materials that are likely due to varying optical absorption coefficients due to locally varying stress in the material.

Schroder, D.K.; Park, S.H.; Hwang, I.G.; Mohr, J.B.; Hanly, M.P. [Arizona State Univ., Tempe, AZ (US). Center for Solid State Electronics Research

1993-05-01

329

Thin film polycrystalline silicon solar cells  

SciTech Connect

During the present quarter efficiency of heterostructure solar cells has been increased from 13 to 13.7% for single crystal and from 10.3 to 11.2% for polysilicon. For polysilicon the improvements can be attributed to reductions in grid-area coverage and in reflection losses and for single crystal to a combination of reduction in grid-area coverage and increase in fill factor. The heterostructure cells in both cases were IT0/n-Si solar cells. Degradation in Sn0/sub 2//n-Si solar cells can be greatly reduced to negligible proportions by proper encapsulation. The cells used in stability tests have an average initial efficiency of 11% which reduces to a value of about 10.5% after 6 months of exposure to sunlight and ambient conditions. This small degradation occurs within the first month, and the efficiency remains constant subsequently. The reduction in efficiency is due to a decrease in the open-circuit voltage only, while the short-circuit current and fill factor remain constant. The effects of grain-size on the Hall measurements in polysilicon have been analyzed and interpreted, with some modifications, using a model proposed by Bube. This modified model predicts that the measured effective Hall voltage is composed of components originating from the bulk and space-charge region. For materials with large grains, the carrier concentration is independent of the inter-grain boundary barrier, whereas the mobility is dependent on it. However, for small rains, both the carrier density and mobility depend on the barrier. These predictions are consistant with experimental results of mm-size Wacker polysilicon and ..mu..m-size NTD polysilicon.

Ghosh, A. K.; Feng, T.; Eustace, D. J.; Maruska, H. P.

1980-01-01

330

Defect behavior of polycrystalline solar cell silicon  

NASA Astrophysics Data System (ADS)

The major objective of this study, conducted from October 1988 to September 1991, was to gain an understanding of the behavior of impurities in polycrystalline silicon and the influence of these impurities on solar cell efficiency. The authors studied edge-defined film-fed growth (EFG) and cast poly-Si materials and solar cells. With EFG Si they concentrated on chromium-doped materials and cells to determine the role of Cr on solar cell performance. Cast poly-Si samples were not deliberately contaminated. Samples were characterized by cell efficiency, current-voltage, deep-level transient spectroscopy (DLTS), surface photovoltage (SPV), open-circuit voltage decay, secondary ion mass spectrometry, and Fourier transform infrared spectroscopy measurements. They find that Cr forms Cr-B pairs with boron at room temperature and these pairs dissociate into Cr(i)(sup +) and B(sup -) during anneals at 210 degrees C for 10 min. Following the anneal, Cr-B pairs reform at room temperature with a time constant of 230 h. Chromium forms CrSi2 precipitates in heavily contaminated regions and they find evidence of CrSi2 gettering, but a lack of chromium segregation or precipitation to grain boundaries and dislocations. Cr-B pairs have well defined DLTS peaks. However, DLTS spectra of other defects are not well defined, giving broad peaks indicative of defects with a range of energy levels in the band gap. In some high-stress, low-efficiency cast poly-Si they detect SiC precipitates, but not in low-stress, high-efficiency samples. SPV measurements result in nonlinear SPV curves in some materials that are likely due to varying optical absorption coefficients due to locally varying stress in the material.

Schroder, D. K.; Park, S. H.; Hwang, I. G.; Mohr, J. B.; Hanly, M. P.

1993-05-01

331

Materials That Enhance Efficiency and Radiation Resistance of Solar Cells  

NASA Technical Reports Server (NTRS)

A thin layer (approximately 10 microns) of a novel "transparent" fluorescent material is applied to existing solar cells or modules to effectively block and convert UV light, or other lower solar response waveband of solar radiation, to visible or IR light that can be more efficiently used by solar cells for additional photocurrent. Meanwhile, the layer of fluorescent coating material remains fully "transparent" to the visible and IR waveband of solar radiation, resulting in a net gain of solar cell efficiency. This innovation alters the effective solar spectral power distribution to which an existing cell gets exposed, and matches the maximum photovoltaic (PV) response of existing cells. By shifting a low PV response waveband (e.g., UV) of solar radiation to a high PV response waveband (e.g. Vis-Near IR) with novel fluorescent materials that are transparent to other solar-cell sensitive wavebands, electrical output from solar cells will be enhanced. This approach enhances the efficiency of solar cells by converting UV and high-energy particles in space that would otherwise be wasted to visible/IR light. This innovation is a generic technique that can be readily implemented to significantly increase efficiencies of both space and terrestrial solar cells, without incurring much cost, thus bringing a broad base of economical, social, and environmental benefits. The key to this approach is that the "fluorescent" material must be very efficient, and cannot block or attenuate the "desirable" and unconverted" waveband of solar radiation (e.g. Vis-NIR) from reaching the cells. Some nano-phosphors and novel organometallic complex materials have been identified that enhance the energy efficiency on some state-of-the-art commercial silicon and thin-film-based solar cells by over 6%.

Sun, Xiadong; Wang, Haorong

2012-01-01

332

Development of high-performance GaInAsP solar cells for tandem solar cell applications  

Microsoft Academic Search

Recent results in the development of high-efficiency, low-bandgap GaInAsP solar cells epitaxially grown and lattice matched on InP substrates are presented. Such cells are intended to be used as optimum bottom cell components in tandem solar cells. Assuming that a GaAs-based top cell is used, computer simulation of the potential bottom cell performance as a function of the cell bandgap

M. W. Wanlass; J. S. Ward; T. A. Gessert; K. A. Emery; G. S. Horner; T. J. Coutts; G. F. Virshup; M. L. Ristow

1990-01-01

333

A theoretical analysis of the current-voltage characteristics of solar cells  

NASA Technical Reports Server (NTRS)

The following topics are discussed: (1) dark current-voltage characteristics of solar cells; (2) high efficiency silicon solar cells; (3) short circuit current density as a function of temperature and the radiation intensity; (4) Keldysh-Franz effects and silicon solar cells; (5) thin silicon solar cells; (6) optimum solar cell designs for concentrated sunlight; (7) nonuniform illumination effects of a solar cell; and (8) high-low junction emitter solar cells.

Fang, R. C. Y.; Hauser, J. R.

1979-01-01

334

Quantum Dots Investigated for Solar Cells  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center has been investigating the synthesis of quantum dots of CdSe and CuInS2 for use in intermediate-bandgap solar cells. Using quantum dots in a solar cell to create an intermediate band will allow the harvesting of a much larger portion of the available solar spectrum. Theoretical studies predict a potential efficiency of 63.2 percent, which is approximately a factor of 2 better than any state-of-the-art devices available today. This technology is also applicable to thin-film devices--where it offers a potential four-fold increase in power-to-weight ratio over the state of the art. Intermediate-bandgap solar cells require that quantum dots be sandwiched in an intrinsic region between the photovoltaic solar cell's ordinary p- and n-type regions (see the preceding figure). The quantum dots form the intermediate band of discrete states that allow sub-bandgap energies to be absorbed. However, when the current is extracted, it is limited by the bandgap, not the individual photon energies. The energy states of the quantum dot can be controlled by controlling the size of the dot. Ironically, the ground-state energy levels are inversely proportional to the size of the quantum dots. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Ba Wendi et al., in the early 1990's. The most studied quantum dots prepared by this method have been of CdSe. To produce these dots, researchers inject a syringe of the desired organometallic precursors into heated triocytlphosphine oxide (TOPO) that has been vigorously stirred under an inert atmosphere (see the following figure). The solution immediately begins to change from colorless to yellow, then orange and red/brown, as the quantum dots increase in size. When the desired size is reached, the heat is removed from the flask. Quantum dots of different sizes can be identified by placing them under a "black light" and observing the various color differences in their fluorescence (see the photograph).

Bailey, Sheila G.; Castro, Stephanie L.; Raffaelle, Ryne P.; Hepp, Aloysius F.

2001-01-01

335

Nanorods and nanotubes for solar cells.  

PubMed

Nanorods and nanotubes as photoactive materials as well as electrodes in photovoltaic cells have been launched a few years ago, and the literature in this field started to appear only recently. The first steps have shown both advantages and disadvantages of their application, and the main expectation associated with their effective charge transport has not been realized completely. This article aims to review both the first and the recent tendencies in the development and application of nanorod and nanotube materials in photovoltaic cells. Two basic techniques of synthesis of crystalline nanorod structures are described, the top-down and bottom-up approaches, respectively. Design and photovoltaic performance of solar cells based on various semiconductor nanorod materials, such as TiO2, ZnO, CdS, CdSe, CdTe, CuO, Si are presented and compared with respective solar cells based on semiconductor nanoparticles. Specific of synthesis and application of carbon nanotubes in photovoltaic devices is also reviewed. PMID:18468059

Kislyuk, V V; Dimitriev, O P

2008-01-01

336

Algaas Top Solar Cell for Mechanical Attachment in a Multi-Junction Tandem Concentrator Solar Cell Stack  

Microsoft Academic Search

Free-standi ng, transparent, tunable bandgap A1 ,Gal_,As top solar cell s have been fabricated for mechanical attachment in a four terminal tandem stack solar cell. Evaluation of the device results have demonstrated 1.80 eV top solar cells with efficiencies of 18% (1OOX. AMO) which would yield stack efficiencies of 31% (lOOX, AMO) with a silicon bottom cell. When full y

L. C. DiNetta; M. H. Hannon; J. R. Cummings; J. B. McNeely; A. M. Barnett

1990-01-01

337

AlGaAs top solar cell for mechanical attachment in a multi-junction tandem concentrator solar cell stack  

Microsoft Academic Search

Free-standing, transparent, tunable bandgap AlxGa1-xAs top solar cells have been fabricated for mechanical attachment in a four terminal tandem stack solar cell. Evaluation of the device results has demonstrated 1.80 eV top solar cells with efficiencies of 18 percent (100 X, and AM0) which would yield stack efficiencies of 31 percent (100 X, AM0) with a silicon bottom cell. When

L. C. Dinetta; M. H. Hannon; J. R. Cummings; J. B. McNeeley; Allen M. Barnett

1990-01-01

338

High efficiency, radiation-hard solar cells  

SciTech Connect

The direct gap of the In{sub 1-x}Ga{sub x}N alloy system extends continuously from InN (0.7 eV, in the near IR) to GaN (3.4 eV, in the mid-ultraviolet). This opens the intriguing possibility of using this single ternary alloy system in single or multi-junction (MJ) solar cells of the type used for space-based surveillance satellites. To evaluate the suitability of In{sub 1-x}Ga{sub x}N as a material for space applications, high quality thin films were grown with molecular beam epitaxy and extensive damage testing with electron, proton, and alpha particle radiation was performed. Using the room temperature photoluminescence intensity as a indirect measure of minority carrier lifetime, it is shown that In{sub 1-x}Ga{sub x}N retains its optoelectronic properties at radiation damage doses at least 2 orders of magnitude higher than the damage thresholds of the materials (GaAs and GaInP) currently used in high efficiency MJ cells. This indicates that the In{sub 1-x}Ga{sub x}N is well-suited for the future development of ultra radiation-hard optoelectronics. Critical issues affecting development of solar cells using this material system were addressed. The presence of an electron-rich surface layer in InN and In{sub 1-x}Ga{sub x}N (0 < x < 0.63) was investigated; it was shown that this is a less significant effect at large x. Evidence of p-type activity below the surface in Mg-doped InN was obtained; this is a significant step toward achieving photovoltaic action and, ultimately, a solar cell using this material.

Ager III, J.W.; Walukiewicz, W.

2004-10-22

339

Proton radiation analysis of multi-junction space solar cells  

Microsoft Academic Search

We report experimental results of proton irradiations with various energies on InGaP\\/GaAs\\/Ge triple-junction (3J) solar cells. The 3J solar cells consisting of stacked three different sub-cells (InGaP top cell, GaAs middle cell and Ge bottom cell) were irradiated with various energies of protons. Proton penetration depth was calculated by the TRIM program. Currentvoltage characteristic under AM0 simulated light and the

T. Sumita; M. Imaizumi; S. Matsuda; T. Ohshima; A. Ohi; H. Itoh

2003-01-01

340

High efficiency solar cells combining a perovskite and a silicon heterojunction solar cells via an optical splitting system  

NASA Astrophysics Data System (ADS)

We have applied an optical splitting system in order to achieve very high conversion efficiency for a full spectrum multi-junction solar cell. This system consists of multiple solar cells with different band gap optically coupled via an "optical splitter." An optical splitter is a multi-layered beam splitter with very high reflection in the shorter-wave-length range and very high transmission in the longer-wave-length range. By splitting the incident solar spectrum and distributing it to each solar cell, the solar energy can be managed more efficiently. We have fabricated optical splitters and used them with a wide-gap amorphous silicon (a-Si) solar cell or a CH3NH3PbI3 perovskite solar cell as top cells, combined with mono-crystalline silicon heterojunction (HJ) solar cells as bottom cells. We have achieved with a 550 nm cutoff splitter an active area conversion efficiency of over 25% using a-Si and HJ solar cells and 28% using perovskite and HJ solar cells.

Uzu, Hisashi; Ichikawa, Mitsuru; Hino, Masashi; Nakano, Kunihiro; Meguro, Tomomi; Hernndez, Jos Luis; Kim, Hui-Seon; Park, Nam-Gyu; Yamamoto, Kenji

2015-01-01

341

Thin silicon solar cell performance characteristics  

NASA Technical Reports Server (NTRS)

Refined techniques for surface texturizing, back surface field and back surface reflector formation were evaluated for use with shallow junction, single-crystal silicon solar cells. Each process was characterized individually and collectively as a function of device thickness and bulk resistivity. Among the variables measured and reported are open circuit voltage, short circuit current and spectral response. Substantial improvements were obtained by the utilization of a low cost aluminum paste process to simultaneously remove the unwanted n(+) diffused region, form the back surface field and produce an ohmic contact metallization. The highly effective BSF which results from applying this process has allowed fabrication of cells 0.05 mm thick with initial outputs as high as 79.5 mW/4 sq cm (28 C, AM0) and superior electron radiation tolerance. Cells of 0.02 mm to 0.04 mm thickness have been fabricated with power to mass ratios well in excess of 2 watts per gram.

Gay, C. F.

1978-01-01

342

18-percent efficient terrestrial silicon solar cells  

NASA Technical Reports Server (NTRS)

Silicon solar cells are described which operate at energy conversion efficiencies in excess of 18 percent under standard terrestrial test conditions (AM1.5, 100 mW/sq cm, 28 C). These are believed to be the most efficient silicon cells reported to date. The high efficiency is a result of the combination of high open-circuit voltage due to the careful attention paid to passivation of the top surface of the cell; high fill factors due to the high open-circuit voltage and low parasitic resistance losses; and high short-circuit current due to the use of shallow diffusions, a low grid coverage, and an optimized double-layer antireflection coating.

Blakers, A. W.; Green, M. A.; Jiqun, S.; Keller, E. M.; Wenham, S. R.; Godfrey, R. B.; Szpitalak, T.; Willison, M. R.

1984-01-01

343

Solare Cell Roof Tile And Method Of Forming Same  

DOEpatents

A solar cell roof tile includes a front support layer, a transparent encapsulant layer, a plurality of interconnected solar cells and a backskin layer. The front support layer is formed of light transmitting material and has first and second surfaces. The transparent encapsulant layer is disposed adjacent the second surface of the front support layer. The interconnected solar cells has a first surface disposed adjacent the transparent encapsulant layer. The backskin layer has a first surface disposed adjacent a second surface of the interconnected solar cells, wherein a portion of the backskin layer wraps around and contacts the first surface of the front support layer to form the border region. A portion of the border region has an extended width. The solar cell roof tile may have stand-offs disposed on the extended width border region for providing vertical spacing with respect to an adjacent solar cell roof tile.

Hanoka, Jack I. (Brookline, MA); Real, Markus (Oberberg, CH)

1999-11-16

344

Advantages of thin silicon solar cells for use in space  

NASA Technical Reports Server (NTRS)

A system definition study on the Solar Power Satellite System showed that a thin, 50 micrometers, silicon solar cell has significant advantages. The advantages include a significantly lower performance degradation in a radiation environment and high power-to-mass ratios. The advantages of such cells for an employment in space is further investigated. Basic questions concerning the operation of solar cells are considered along with aspects of radiation induced performance degradation. The question arose in this connection how thin a silicon solar cell had to be to achieve resistance to radiation degradation and still have good initial performance. It was found that single-crystal silicon solar cells could be as thin as 50 micrometers and still develop high conversion efficiencies. It is concluded that the use of 50 micrometer silicon solar cells in space-based photovoltaic power systems would be advantageous.

Denman, O. S.

1978-01-01

345

Studies of silicon p-n junction solar cells  

NASA Technical Reports Server (NTRS)

To provide theoretical support for investigating different ways to obtain high open-circuit voltages in p-n junction silicon solar cells, an analytical treatment of heavily doped transparent-emitter devices is presented that includes the effects of bandgap narrowing, Fermi-Dirac statistics, a doping concentration gradient, and a finite surface recombination velocity at the emitter surface. Topics covered include: (1) experimental determination of bandgap narrowing in the emitter of silicon p-n junction devices; (2) heavily doped transparent regions in junction solar cells, diodes, and transistors; (3) high-low-emitter solar cell; (4) determination of lifetimes and recombination currents in p-n junction solar cells; (5) MOS and oxide-charged-induced BSF solar cells; and (6) design of high efficiency solar cells for space and terrestrial applications.

Neugroschel, A.; Lindholm, F. A.

1979-01-01

346

Characterization of production GaAs solar cells for space  

NASA Technical Reports Server (NTRS)

The electrical performance of GaAs solar cells was characterized as a function of irradiation with protons and electrons with the underlying goal of producing solar cells suitable for use in space. Proton energies used varied between 50 keV and 10 MeV, and damage coefficients were derived for liquid phase epitaxy GaAs solar cells. Electron energies varied between 0.7 and 2.4 MeV. Cells from recent production runs were characterized as a function of electron and proton irradiation. These same cells were also characterized as a function of solar intensity and operating temperature, both before and after the electron irradiations. The long term stability of GaAs cells during photon exposure was examined. Some cells were found to degrade with photon exposure and some did not. Calibration standards were made for GaAs/Ge solar cells by flight on a high altitude balloon.

Anspaugh, B. E.

1988-01-01

347

AlGaAs top solar cell for mechanical attachment in a multi-junction tandem concentrator solar cell stack  

Microsoft Academic Search

Free-standing, transparent, tunables bandgap AlxGa1-xAs top solar cells have been fabricated for mechanical attachment in a four-terminal tandem stack solar cell. The device has 1.8 eV top solar cells with efficiencies of 18% (100X, AM0), which would yield stack efficiencies of 31% (100X, AM0) with a silicon bottom cell. When fully developed, the AlxGa1-x As\\/Si mechanically stacked two-junction solar cell

L. DiNetta; G. H. Negley; M. H. Hannon; J. R. Cummings; J. B. McNeely; A. M. Barnett

1990-01-01

348

High efficiency solar cells for laser power beaming applications  

NASA Technical Reports Server (NTRS)

Understanding solar cell response to pulsed laser outputs is important for the evaluation of power beaming applications. The time response of high efficiency GaAs and silicon solar cells to a 25 nS monochromatic pulse input is described. The PC-1D computer code is used to analyze the cell current during and after the pulse for various conditions.

Jain, Raj K.; Landis, G. A.

1995-01-01

349

50 ?m thin solar cells with 17.0% efficiency  

Microsoft Academic Search

Monocrystalline silicon solar cells with thicknesses below 50?m manufactured by the transfer layer process at ipe reach efficiencies as high as 17.0%. We present a thin film solar cell, which is not attached to a glass superstrate, opening new process opportunities, as for example the usage of flexible superstrates. We show a free-standing 47?m thin solar cell with a record

Michael Reuter; Willi Brendle; Osama Tobail; Jrgen H. Werner

2009-01-01

350

Large area shunt defect free GaAs solar cells  

Microsoft Academic Search

Shunt defects have been found to be the type of defect that can degrade and cause failure in GaAs solar cells. Because of their catastrophic effects, it is necessary to ensure that no shunt defects are formed in the solar cell. A technique for fabricating large-area shunt-defect-free GaAs solar cells has been investigated. A Be-doped GaAlAs window layer was grown

Louis C. Kilmer; Allen M. Barnett

1990-01-01

351

A cadmium sulphide-solid electrolyte photoelectrochemical solar cell  

NASA Astrophysics Data System (ADS)

Cadmium sulphide thin film was prepared by a chemical bath deposition technique. This semiconducting film was used to fabricate a photoelectrochemical solar cell with a solid electrolyte prepared by capturing a ferrous/ferric cyanide redox couple in an agar-agar gel matrix. The performance of this solid electrolyte photoelectrochemical solar cell has been studied and compared with a liquid electrolyte-CdS photoelectrochemical solar cell containing the same redox couple.

Khare, Neeraj

1988-09-01

352

Annual report on high-intensity solar cells  

Microsoft Academic Search

Described is a program to support the Sandia National Laboratories effort to develop high-efficiency, high-concentration solar cells. During the past year this support has taken the following forms: providing general analytic support for the development of high-efficiency IBC solar cells, and developing a two-dimensional computer code suitable for modelling the performance of the IBC solar cell and other high concentration

R. J. Schwartz; M. S. Lundstrom; J. L. Gray

1982-01-01

353

Metamorphic and Lattice-Matched Solar Cells Under Concentration  

Microsoft Academic Search

Metamorphic III-V semiconductor materials offer access to bandgaps that span key portions of the solar spectrum, enabling new bandgap combinations in multijunction solar cells, and increasing both theoretical and practical efficiency limits for terrestrial concentrator cells. Experimental results are given for the quantum efficiency of metamorphic GaInAs solar cells with bandgap from 1.1 to 1.4 eV, and for metamorphic GaInP

R. R. King; D. C. Law; K. M. Edmondson; C. M. Fetzer; R. A. Sherif; G. S. Kinsey; D. D. Krut; H. L. Cotal; N. H. Karam

2006-01-01

354

A PHOTOCHEMICAL BOX MODEL FOR URBAN AIR QUALITY SIMULATION  

EPA Science Inventory

A simple 'box-approach' to air quality simulation modeling has been developed in conjunction with a newly formulated photochemical kinetic mechanism to produce an easily applied Photochemical Box Model (PBM). This approach represents an urban area as a single cell 20 km in both l...

355

Laser processes for future solar cells  

NASA Astrophysics Data System (ADS)

The photovoltaic (PV) industry requires higher efficiencies at lower manufacturing costs to become competitive with other power generation techniques. There are several approaches to increase the efficiency of solar cells. For example enhancements of the way photons are absorbed and how they generate charge carriers with low losses. Today, the so called first generation of photovoltaic devices based on crystalline silicon wafers are produced on a multi-GW-level. However, in most production lines there is only one laser process used to electrically isolate front and rear side of the cell. Lasers are predestined to generate local structures which will be required to manufacture high efficient solar cells. As an example we will show results on the interaction of ultra short laser pulses with dielectric films on silicon. Second generation photovoltaic modules are based on thin films. These modules are monolithically interconnected by laser scribing of the films. Tools for amorphous silicon are well established, while there are a lot of challenges to scribe CIGS layers. Within this paper we will show new results on the temporal evolution of a laser induced "lift-off" process to scribe the molybdenum back electrode.

Letsch, Andreas; Bartl, Dominik; Diez, Michael; Gauch, Roland; Michalowski, Andreas; Hafner, Margit

2012-03-01

356

Photon management structures for solar cells  

NASA Astrophysics Data System (ADS)

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 ?m 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 processes.

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

2012-06-01

357

Research opportunities in polycrystalline compound solar cells  

NASA Astrophysics Data System (ADS)

Polycrystalline photovoltaic (PV) materials show substantial promise for achieving the U.S. Department of Energy PV costs and performance goals. Cadmium telluride (CdTe) and CuInSe2 (CIS) both have recently demonstrated device efficiencies in the 15 percent range with promise of achieving 20 percent efficiencies. Large area thin film CIS and CdTe modules in the 0.4 to 0.7 m2 size have also been fabricated with aperture efficiencies approaching ten percent. In spite of these results, polycrystalline thin film materials are relatively unexplored. Fundamental research opportunities in materials for thin film solar cells can be categorized under three major headings, from the most general to the most specific: areas with long-range potentialities, areas with a larger exploratory content, and areas with specific need. Each of these issues can play a vital role in the development of improved solar cells. The discussion of research opportunities in this paper starts with the more general opportunities and works its way to the most specific ones: (i) updating the basic investigation of defect properties and compensation in Group II-VI and related materials; exploring the basic materials science of the growth process for synthesis from layers of the elements, and exploring the potentials of bandgap engineering; (ii) search for new materials, interactions between defects and grain boundaries in polycrystalline materials, and exploration of the p-i-n structure for solar cells in a more general way; and (iii) doping of and contacts to p-CdTe, junction transport and effects of heat treatments on CdTe and CuInSe2, and development of Group II-VI ternaries.

Bube, Richard H.; Mitchell, Kim W.

1993-01-01

358

Elongated nanostructures for radial junction solar cells.  

PubMed

In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented. PMID:24088584

Kuang, Yinghuan; Vece, Marcel Di; Rath, Jatindra K; Dijk, Lourens van; Schropp, Ruud E I

2013-10-01

359

Hybrid Inorganic-Organic Heterojunction Solar Cell  

NASA Astrophysics Data System (ADS)

In this study, solar cells were fabricated by spin-coating polyaniline (PANI) base (EB) over an n-type Si substrate. The final heterojunction's device structure was Al/ n-type Si/EB/Au. The electrical properties of the resultant device were investigated by measuring the current density-voltage ( J- V), capacitance-voltage ( C- V), and impedance characteristics in the dark and under illumination. N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and tetrahydrofuran (THF) were used as solvents for EB. The effects of these solvents on the photovoltaic cell parameters were investigated, and the open-circuit voltage ( V oc), short-circuit current density ( J sc), fill factor (FF), and energy conversion efficiency ( ?) were determined. It was found that heterojunctions fabricated using EB dissolved in NMP, DMF, and THF produced J sc of 10 mA/cm2, 5.123 mA/cm2, and 2.78 mA/cm2, respectively. Rollover and crossover phenomena in the J- V curves under illumination were explained based on the back-contact barrier and surface recombination of electrons at the back contact. The linearity of Mott-Schottky plots indicated the formation of a heterojunction between EB and n-type Si, and the slope of 1/ C 2 versus voltage changed under illumination. The high values of shunt resistance were decreased under illumination, indicating that the efficiency of this type of heterojunction solar cell was limited by shunt resistance and the narrow absorption range of the solar spectrum by EB.

Ebrahim, Shaker; Soliman, Moataz; Abdel-Fattah, Tarek M.

2011-09-01

360

Will Organic Synthesis Within Icy Grains or on Dust Surfaces in the Primitive Solar Nebula Completely Erase the Effects of Photochemical Self Shielding?  

NASA Technical Reports Server (NTRS)

There are at least 3 separate photochemical self-shielding models with different degrees of commonality. All of these models rely on the selective absorption of (12))C(16)O dissociative photons as the radiation source penetrates through the gas allowing the production of reactive O-17 and O-18 atoms within a specific volume. Each model also assumes that the undissociated C(16)O is stable and does not participate in the chemistry of nebular dust grains. In what follows we will argue that this last, very important assumption is simply not true despite the very high energy of the CO molecular bond.

Nuth, Joseph A., III; Johnson, Natasha M.

2012-01-01

361

Cold crucible Czochralski for solar cells  

NASA Technical Reports Server (NTRS)

The efficiency and radiation resistance of present silicon solar cells are a function of the oxygen and carbon impurities and the boron doping used to provide the proper resistivity material. The standard Czochralski process used grow single crystal silicon contaminates the silicon stock material due to the use of a quartz crucible and graphite components. The use of a process which replaces these elements with a water cooled copper to crucible has provided a major step in providing gallium doped (100) crystal orientation, low oxygen, low carbon, silicon. A discussion of the Cold Crucible Czochralski process and recent float Zone developments is provided.

Trumble, T. M.

1982-01-01

362

Transmutation doping of silicon solar cells  

NASA Technical Reports Server (NTRS)

Normal isotopic silicon contains 3.05% of Si-30 which transmutes to P-31 after thermal neutron absorption, with a half-life of 2.6 hours. This reaction is used to introduce extremely uniform concentrations of phosphorus into silicon, thus eliminating the areal and spatial inhomogeneities characteristic of chemical doping. Annealing of the lattice damage in the irradiated silicon does not alter the uniformity of dopant distribution. Transmutation doping also makes it possible to introduce phosphorus into polycrystalline silicon without segregation of the dopant at the grain boundaries. The use of neutron transmutation doped (NTD) silicon in solar cell research and development is discussed.

Wood, R. F.; Westbrook, R. D.; Young, R. T.; Cleland, J. W.

1977-01-01

363

The future of high efficiency solar cells  

NASA Technical Reports Server (NTRS)

Research approaches to obtain solar cell modules with 1 sun efficiencies of 20-30 percent at air mass 1 are now well understood. Such high efficiency modules should become available in the near future. It can be expected that these modules will be extensively used in terrestrial power generation, space power generation, and consumer electronics. To achieve practical module efficiencies significantly above 30 percent, it will be necessary to employ concepts other than spectral splitting, such as spectral compression and broad band detection. A major breakthrough in these areas is not anticipated at this time.

Fan, J. C. C.

1984-01-01

364

Method of fabricating bifacial tandem solar cells  

SciTech Connect

A method of fabricating on a semiconductor substrate bifacial tandem solar cells with semiconductor subcells having a lower bandgap than the substrate bandgap on one side of the substrate and with subcells having a higher bandgap than the substrate on the other including, first, growing a lower bandgap subcell on one substrate side that uses only the same periodic table group V material in the dislocation-reducing grading layers and bottom subcells as is present in the substrate and after the initial growth is complete and then flipping the substrate and growing the higher bandgap subcells on the opposite substrate side which can be of different group V material.

Wojtczuk, Steven J; Chiu, Philip T; Zhang, Xuebing; Gagnon, Edward; Timmons, Michael

2014-10-07

365

Dip-coated sheet silicon solar cells  

NASA Technical Reports Server (NTRS)

A cost-effective method is being developed for producing solar cell quality sheet silicon by dip coating inexpensive ceramic substrates with a thin layer of large grain silicon. Mullite (Aluminum Silicate) ceramic substrates coated with a thin layer of graphite have been dipped into molten silicon to produce 20-150 micron thick layers having grain sizes as large as .4 cm x 4 cm. With these silicon layers photovoltaic diodes have been fabricated with measured and inherent conversion efficiencies of 4% and 7%, respectively.

Heaps, J. D.; Maciolek, R. B.; Zook, J. D.; Scott, M. W.

1976-01-01

366

Plastic solar cell interface and morphological characterization  

NASA Astrophysics Data System (ADS)

Plastic solar cell research has become an intense field of study considering these devices may be lightweight, flexible and reduce the cost of photovoltaic devices. The active layer of plastic solar cells are a combination of two organic components which blend to form an internal morphology. Due to the poor electrical transport properties of the organic components it is important to understand how the morphology forms in order to engineer these materials for increased efficiency. The focus of this thesis is a detailed study of the interfaces between the plastic solar cell layers and the morphology of the active layer. The system studied in detail is a blend of P3HT and PCBM that acts as the primary absorber, which is the electron donor, and the electron acceptor, respectively. The key morphological findings are, while thermal annealing increases the crystallinity parallel to the substrate, the morphology is largely unchanged following annealing. The deposition and mixing conditions of the bulk heterojunction from solution control the starting morphology. The spin coating speed, concentration, solvent type, and solution mixing time are all critical variables in the formation of the bulk heterojunction. In addition, including the terminals or inorganic layers in the analysis is critical because the inorganic surface properties influence the morphology. Charge transfer in the device occurs at the material interfaces, and a highly resistive transparent conducting oxide layer limits device performance. It was discovered that the electron blocking layer between the transparent conducting oxide and the bulk heterojunction is compromised following annealing. The electron acceptor material can diffuse into this layer, a location which does not benefit device performance. Additionally, the back contact deposition is important since the organic material can be damaged by the thermal evaporation of Aluminum, typically used for plastic solar cells. Depositing a thin thermal and momentum blocking layer of lithium fluoride prevents damage which ultimately leads to higher efficiencies. Finally, new materials have been synthesized with better electronic properties and stability. Characterization of the polymer properties and how they assemble is important for high device performance. One new promising polymer, Polybenzo[1,2-b:4,5- b']dithiophene-4,7-dithien-2-yl-2,1,3-benzothiadiazole (PBnDT-DTBT), was characterized with PCBM and it was found that this polymer assembles similarly to previously studied polymers. The efficiency gained with this new polymer is obtained from an improvement in the materials electronic properties since the morphology closely resembles the P3HT:PCBM system.

Guralnick, Brett W.

367

Nanocarbon counterelectrode for dye sensitized solar cells  

SciTech Connect

Nanosize carbon powders were deposited on conducting glass substrate for counterelectrode application in dye sensitized solar cell (DSSC). Electrochemical impedance measurement shows that charge transfer resistance of carbon electrode in liquid electrolyte is 0.74 {omega} cm{sup -2}, which is two times less than that of screen printed platinum. Using such counterelectrode and dye sensitized TiO{sub 2} working electrode, DSSC was fabricated. Under one sun illumination (AM1.5, P{sub in} of 100 mW cm{sup -2}), carbon counterelectrode DSSC shows 6.73% overall energy conversion efficiency with good stability.

Ramasamy, Easwaramoorthi; Lee, Won Jae; Lee, Dong Yoon; Song, Jae Sung [Electric and Magnetic Devices Research Group, Korea Electrotechnology Research Institute, Changwon 641-120 (Korea, Republic of)

2007-04-23

368

Investigation of back surface fields effect on bifacial solar cells  

NASA Astrophysics Data System (ADS)

A bifacial solar cell, in contrast with a conventional monofacial solar cell, produces photo-generated current from both front and back sides. Bifacial solar cell is an attractive candidate for enhancing photovoltaic (PV) market competitiveness as well as supporting the current efforts to increase efficiency and lower material costs. This paper reports on the fabrication of bifacial solar cells using phosphorus-oxytrichloride (POCl3) emitter formation on p-type, nanotextured silicon (Si) wafer. Backside surface field was formed through Al-diffusion using conventional screen-printing process. Bifacial solar cells with a structure of n+pp+ with and without back surface field (BSF) were fabricated in which silicon nitride (SiN) anti reflection and passivation films were coated on both sides, followed by screen printing of Argentum (Ag) and Argentum/Aluminum (Ag/Al) on front and back contacts, respectively. Bifacial solar cells without BSF exhibited open circuit voltage (VOC) of 535 mV for front and 480 mV for back surface. With Al-alloyed BSF bifacial solar cells, the VOC improved to 580 mV for the front surface and 560 mV for the back surface. Simulation of bifacial solar cells using PC1D and AFORS software demonstrated good agreement with experimental results. Simulations showed that best bifacial solar cells are achieved through a combination of high lifetime wafer, low recombination back surface field, reduced contact resistance, and superior surface passivation.

Sepeai, Suhaila; Sulaiman, M. Y.; Sopian, Kamaruzzaman; Zaidi, Saleem H.

2012-11-01

369

Testing of gallium arsenide solar cells on the CRRES vehicle  

NASA Technical Reports Server (NTRS)

A flight experiment was designed to determine the optimum design for gallium arsenide (GaAs) solar cell panels in a radiation environment. Elements of the experiment design include, different coverglass material and thicknesses, welded and soldered interconnects, different solar cell efficiencies, different solar cell types, and measurement of annealing properties. This experiment is scheduled to fly on the Combined Release and Radiation Effects Satellite (CRRES). This satellite will simultaneously measure the radiation environment and provide engineering data on solar cell degradation that can be directly related to radiation damage.

Trumble, T. M.

1985-01-01

370

High efficiency thin-film GaAs solar cells  

NASA Technical Reports Server (NTRS)

Several oxidation techniques are discussed which have been found to increase the open circuit (V sub oc) of metal-GaAs Schottky barrier solar cells, the oxide chemistry, attempts to measure surface state parameters, the evolving characteristics of the solar cell as background contamination (has been decreased, but not eliminated), results of focused Nd/YAG laser beam recrystallization of Ge films evaporated onto tungsten, and studies of AMOS solar cells fabricated on sliced polycrystalline GaAs wafers. Also discussed are projected materials availability and costs for GaAs thin-film solar cells.

Stirn, R. J.

1977-01-01

371

T and B Cell Immunity can be Reconstituted with Mismatched Hematopoietic Stem Cell Transplantation Without Alkylator Therapy in Artemis-Deficient Mice Using Anti-NK Antibody and Photochemically-Treated Sensitized Donor T Cells  

PubMed Central

Children with Artemis-deficient T-B-NK+ SCID (SCIDA) have very high risks of graft rejection from NK cells and toxicity from increased sensitivity to alkylating agents used for mismatched hematopoietic stem cell transplantation (HSCT). We evaluated the use of a non-alkylating agent regimen prior to HSCT in Artemis-deficient (mArt-/-) C57Bl/6 (B6) mice to open marrow niches and achieve long-term multilineage engraftment with full T and B cell immune reconstitution. We found that both partial depletion of recipient NK cells using anti-NK1.1 monoclonal antibody and donor T cells sensitized to recipient splenocytes were necessary. BALB/c sensitized T cells (STC) were photochemically -treated (PCT) with psoralen and UVA light to inhibit proliferation, reduce the risk of Graft-versus-host disease (GvHD) and target host hematopoietic stem cells (HSC). 4105 PCT STC co-injected with 1105 lineage-depleted c-kit+ BALB/c HSC resulted in 43.93.3% CD4+, 10.91.2% CD8+ donor T cells in blood; 297.8% and 21.74.0 donor B220+ IgM+ in spleen and bone marrow and 15.03.6% donor Gran-1+ cells in bone marrow at six months post transplant versus 0.020.0.01%, 0.130.10%, 0.530.16%, 0.490.09% and 0.200.06%, respectively, in controls that did not receive PCT STC. We found that STC target host HSC, and that PCT STC are detectable up to only 24 hours following infusion in contrast to non-photochemically treated STC which proliferate resulting in fatal GvHD. Increased mortality in the groups receiving 4-6105 PCT-STC was associated with evidence of GvHD in particular the recipients of 6105 cells. These results show that blocking NK cell mediated resistance and making niches in bone marrow are both essential to achieve multilineage engraftment of mismatched donor cells and T and B cell reconstitution although GvHD is not completely eliminated. PMID:22015994

Xiao, Tony Z; Singh, Kanal; Dunn, Elizabeth; Ramachandran, Rageshree; Cowan, Morton J.

2011-01-01

372

Flatband solar cells: a model for solid-state nano-structured solar cells  

Microsoft Academic Search

Nano-structured solar cells are too complex for standard modeling. Here, we decouple the effects at a nm-scale from those at a \\/spl mu\\/m-scale. The 3D nano-porous geometry is simplified to a quasi-periodical nm-scale ordering of \\

Marc Burgelman; Catelijne Grasso

2003-01-01

373

Network of flatband solar cells as a model for solid-state nanostructured solar cells  

Microsoft Academic Search

Nanostructured solar cells are too complex for standard modeling. Here, we decouple the effects at a microscopic (nm) scale from those at a macroscopic (mum) scale. The three-dimensional nanoporous geometry is simplified to a quasiperiodic nm-scale ordering of ``unit cells,'' each consisting of a TiO2 sphere and its p-semiconductor or dye\\/p-conductor shell. It is shown that, due to the periodic

Marc Burgelman; Catelijne Grasso

2004-01-01

374

Results of the 1970 balloon flight solar cell standardization program  

NASA Technical Reports Server (NTRS)

For the eighth consective year, high-altitude calibration of solar cells was accomplished with the aid of free-flight balloons. Flights were conducted to an altitude of 36,576 m which is above 99.5% of earth's atmosphere where all water vapor levels and significant ozone bands are absent. Solar cells calibrated in this manner are significant used as intensity references in solar simulators and in terrestrial sunlight. Discussed is the method employed for high altitude balloon flight solar cell calibration. Also presented are data collected on 52 standard solar cells on two flights conducted in 1970. Solar cells flown repeatedly on successive flights have shown correlation of better than + or - 1.0%.

Greenwood, R. F.

1972-01-01

375

Recyclable organic solar cells on cellulose nanocrystal substrates  

PubMed Central

Solar energy is potentially the largest source of renewable energy at our disposal, but significant advances are required to make photovoltaic technologies economically viable and, from a life-cycle perspective, environmentally friendly, and consequently scalable. Cellulose nanomaterials are emerging high-value nanoparticles extracted from plants that are abundant, renewable, and sustainable. Here, we report on the first demonstration of efficient polymer solar cells fabricated on optically transparent cellulose nanocrystal (CNC) substrates. The solar cells fabricated on the CNC substrates display good rectification in the dark and reach a power conversion efficiency of 2.7%. In addition, we demonstrate that these solar cells can be easily separated and recycled into their major components using low-energy processes at room temperature, opening the door for a truly recyclable solar cell technology. Efficient and easily recyclable organic solar cells on CNC substrates are expected to be an attractive technology for sustainable, scalable, and environmentally-friendly energy production. PMID:23524333

Zhou, Yinhua; Fuentes-Hernandez, Canek; Khan, Talha M.; Liu, Jen-Chieh; Hsu, James; Shim, Jae Won; Dindar, Amir; Youngblood, Jeffrey P.; Moon, Robert J.; Kippelen, Bernard

2013-01-01

376

Assessment of the dye-sensitized solar cell  

Microsoft Academic Search

The field of solar electricity, or photovoltaics (PV), is rich in that there are many materials and concepts for converting sunlight into electricity. The technologies accepted as conventional are those well along in the process of commercialization. The dye-sensitized solar cell, developed in the 1990s, is a nonconventional solar electric technology that has attracted much attention, perhaps a result of

R. D. McConnell

2002-01-01

377

Basic linear-mode solar-cell simulators  

Microsoft Academic Search

The paper describes basic types of linear-mode power systems for simulating voltage\\/current characteristics of solar cells modules. Starting from a current source with a chain of diodes arranged in parallel (being the most simple equivalent circuit diagram of a solar power module) a very basic solar module simulator using a bipolar power transistor and based on the amplified diode concept

H. Votzi; F. A. Himmelstoss; H. Ertl

2009-01-01

378

A three solar cell system based on a self-supporting, transparent AlGaAs top solar cell  

NASA Technical Reports Server (NTRS)

Development of a three solar cell stack can lead to practical efficiencies greater than 30 percent (1x,AM0). A theoretical efficiency limitation of 43.7 percent at AM0 and one sun is predicted by this model. Including expected losses, a practical system efficiency of 36.8 percent is anticipated. These calculations are based on a 1.93eV/1.43eV/0.89eV energy band gap combination. AlGaAs/GaAs/GaInAsP materials can be used with a six-terminal wiring configuration. The key issues for multijunction solar cells are the top and middle solar cell performance and the sub-bandgap transparency. AstroPower has developed a technique to fabricate AlGaAs solar cells on rugged, self-supporting, transparent AlGaAs substrates. Top solar cell efficiencies greater than 11 percent AM0 have been achieved. State-of-the-art GaAs or InP devices will be used for the middle solar cell. GaInAsP will be used to fabricate the bottom solar cell. This material is lattice-matched to InP and offers a wide range of bandgaps for optimization of the three solar cell stack. Liquid phase epitaxy is being used to grow the quaternary material. Initial solar cells have shown open-circuit voltages of 462 mV for a bandgap of 0.92eV. Design rules for the multijunction three solar cell stack are discussed. The progress in the development of the self-supporting AlGaAs top solar cell and the GaInAsP bottom solar cell is presented.

Negley, Gerald H.; Rhoads, Sandra L.; Terranova, Nancy E.; Mcneely, James B.; Barnett, Allen M.

1989-01-01

379

Novel solar cells in a wire format.  

PubMed

Photovoltaic devices in a wire format have recently attracted increasing attention as, compared with the conventional planar structure, they show unique and promising advantages. For instance, they are light-weight and can be easily woven into clothes or integrated into other structures, which enable applications in electronic textiles and various complex devices. In this tutorial review, the recent advancement in photovoltaic wires including both dye-sensitized and polymer solar cells are described. Two main architectures based on a single core-sheath fiber and twisted fibers are carefully illustrated with an emphasis on the comparison of various substrates which have been focused in past development. The current challenge including low energy conversion efficiency and low stability and future direction of the wire-shaped cell have been finally summarized. PMID:23467786

Chen, Tao; Qiu, Longbin; Yang, Zhibin; Peng, Huisheng

2013-06-21

380

Reducing the Cost of Solar Cells  

SciTech Connect

Solar-powered electricity prices could soon approach those of power from coal or natural gas thanks to collaborative research with solar startup Ampulse Corporation at the National Renewable Energy Laboratory. Silicon wafers account for almost half the cost of today's solar photovoltaic panels, so reducing or eliminating wafer costs is essential to bringing prices down. Current crystalline silicon technology converts energy in a highly efficient manner; however, that technology is manufactured with processes that could stand some improvement. The industry needs a method that is less complex, creates less waste and uses less energy. First, half the refined silicon is lost as dust in the wafer-sawing process, driving module costs higher. Wafers are sawn off of large cylindrical ingots, or boules, of silicon. A typical 2-meter boule loses as many as 6,000 potential wafers during sawing. Second, the wafers produced are much thicker than necessary. To efficiently convert sunlight into electricity, the wafers need be only one-tenth the typical thickness. NREL, the Oak Ridge National Laboratory and Ampulse have partnered on an approach to eliminate this waste and dramatically lower the cost of the finished solar panels. By using a chemical vapor deposition process to grow the silicon on inexpensive foil, Ampulse is able to make the solar cells just thick enough to convert most of the solar energy into electricity. No more sawdust - and no more wasting refined silicon materials. NREL developed the technology to grow high-quality silicon and ORNL developed the metal foil that has the correct crystal structure to support that growth. Ampulse is installing a pilot manufacturing line in NREL's Process Development Integration Laboratory, where solar companies can work closely with lab scientists on integrated equipment to answer pressing questions related to their technology development, as well as rapidly overcoming R and D challenges and risk. NREL's program is focused on transformative innovation in the domestic PV industry. With knowledge and expertise acquired from the PDIL pilot production line tools, Ampulse plans to design a full-scale production line to accommodate long rolls of metal foil. The Ampulse process 'goes straight from pure silicon-containing gas to high-quality crystal silicon film,' said Brent Nelson, the operational manager for the Process Development Integration Laboratory. 'The advantage is you can make the wafer just as thin as you need it - 10 microns or less.' Most of today's solar cells are made out of wafer crystalline silicon, though thin-film cells made of more exotic elements such as copper, indium, gallium, arsenic, cadmium, tellurium and others are making a strong push into the market. The advantage of silicon is its abundance, because it is derived from sand. Silicon's disadvantage is that purifying it into wafers suitable for solar cells can be expensive and energy intensive. Manufacturers add carbon and heat to sand to produce metallurgical-grade silicon, which is useful in other industries, but not yet suitable for making solar cells. So this metallurgical-grade silicon is then converted to pure trichlorosilane (SiCl3) or silane (SiH4) gas. Typically, the purified gas is then converted to create a silicon feedstock at 1,000 degrees Celsius. This feedstock is melted at 1,414 C and recrystallized into crystal ingots that are finally sawed into wafers. The Ampulse method differs in that it eliminates the last two steps in the traditional process and works directly with the silane gas growing only the needed silicon right onto a foil substrate. A team of NREL scientists had developed a way to use a process called hot-wire chemical vapor deposition to thicken silicon wafers with near perfect crystal structure. Using a hot tungsten filament much like the one found in an incandescent light bulb, the silane gas molecules are broken apart and deposited onto the wafer using the chemical vapor deposition technique at about 700 C - a much lower temperature than needed to make the wafer. The hot filament dec

Scanlon, B.

2012-04-01

381

Computer modeling results on all-Si cascade solar cells  

NASA Technical Reports Server (NTRS)

The properties of a cascade solar cell made entirely of silicon are investigated numerically with the goal of developing an optimal silicon solar cell grown by molecular-beam epitaxy. The cascade cell is modeled as two standard back-surface field cells with abrupt junctions connected by a tunnel junction. A cascade cell would have approximately twice the open-circuit voltage of a single cell. If the minority carriers generated in the front cell can be reflected before reaching the tunnel junction, then the cascade cell will show an increase in efficiency over a single cell by a percentage point.

Sparks, P. D.; Allen, F. G.; Daud, T.

1984-01-01

382

nanostructures for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Hierarchical architectures consisting of one-dimensional (1D) nanostructures are of great interest for potential use in energy and environmental applications in recent years. In this work, hierarchical tungsten oxide (WO3) has been synthesized via a facile hydrothermal route from ammonium metatungstate hydrate and implemented as photoelectrode for dye-sensitized solar cells. The urchin-like WO3 micro-patterns are constructed by self-organized nanoscale length 1D building blocks, which are single crystalline in nature, grown along (001) direction and confirm an orthorhombic crystal phase. The obtained powders were investigated by XRD, SEM, TEM and UV-Vis Spectroscopy. The photovoltaic performance of dye-sensitized solar cells based on WO3 photoanodes was investigated. With increasing the calcination temperature of the prepared nanopowders, the light-electricity conversion efficiency ( ?) was increased. The results were attributed to increase the crystallinity of the particles and ease of electron movement. The DSSC based on hierarchical WO3 showed a short-circuit current, an open-circuit voltage, a fill factor, and a conversion efficiency of 4.241 mA/cm2, 0.656 V, 66.74, and 1.85 %, respectively.

Rashad, M. M.; Shalan, A. E.

2014-08-01

383

Photochemical formation of intricarene.  

PubMed

Sunlight is the ultimate driver of biosynthesis but photochemical steps late in biosynthetic pathways are very rare. They appear to play a role in the formation of certain furanocembranoids isolated from Caribbean corals. One of these compounds, intricarene, has been suspected to arise from an intramolecular 1,3-dipolar cycloaddition involving an oxidopyrylium. Here we show, by a combination of experiments and theory, that the oxidopyrylium forms under photochemical conditions and that its cycloaddition occurs via a triplet state. The formation of a complex by-product can be rationalized by another photochemical step that involves a conical intersection. Our work raises the question whether intricarene is biosynthesized in the natural habitat of the corals or is an artefact formed during workup. It also demonstrates that the determination of exact irradiation spectra, in combination with quantum chemical calculations, enables the rationalization of complex reaction pathways that involve multiple excited states. PMID:25470600

Stichnoth, Desiree; Klle, Patrick; Kimbrough, Thomas J; Riedle, Eberhard; de Vivie-Riedle, Regina; Trauner, Dirk

2014-01-01

384

Photochemical crosslinking of soluble wool keratins produces a mechanically stable biomaterial that supports cell adhesion and proliferation.  

PubMed

Keratins extracted from various "hard tissues" such as wool, hair, and nails are increasingly being investigated as a source of abundant, biocompatible materials. In this study we explored a recent photochemical method to crosslink solubilized wool keratoses, with the aim of producing a mechanically favorable biomaterial. Wool proteins were isolated by oxidizing the disulfides and extracting the resulting soluble keratoses. The ?- and ?-keratose fractions were analyzed by liquid chromatography-mass spectrometry to identify their constituent proteins. Hydrogels were produced by covalent crosslinking of the ?-keratoses via a photo-oxidative process catalyzed by blue light, a ruthenium complex, and persulfate. The presence of dityrosine crosslinks was demonstrated by high performance liquid chromatography and mass spectrometry analyses. The crosslinked ?-keratose material had moderate tensile strength and elasticity, and high adhesive strength. The material displayed modest shrinking after crosslinking, however the shrinking could be prevented by crosslinking in the presence of 2.5% glycerol, resulting in gels that did not shrink or swell. Small solutes such as Tris and glycerol influenced the crosslink density and elastic modulus of the crosslinked material. The ?-keratose was able to support adhesion and growth of NIH/3T3 fibroblasts in vitro. The fabrication of mechanically stable keratin biomaterials by this facile photo-crosslinking method may be useful for various tissue engineering applications. PMID:20845488

Sando, Lillian; Kim, Misook; Colgrave, Michelle L; Ramshaw, John A M; Werkmeister, Jerome A; Elvin, Christopher M

2010-12-01

385

ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission  

E-print Network

of the solar radiation can be utilized, and solar tracking is required. By limiting the solar cell emissionORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission angle Emily D Kosten1 solar cell under direct sunlight, light is received from the solar disk, but is re-emitted isotropically

Atwater, Harry

386

The calculated influence of atmospheric conditions on solar cell ISC under direct and global solar irradiances  

NASA Technical Reports Server (NTRS)

Calculations of the influence of atmospheric conditions on solar cell short-circuit current (Isc) are made using a recently developed computer model for solar spectral irradiance distribution. The results isolate the dependence of Isc on changes in the spectral irradiance distribution without the direct influence of the total irradiance level. The calculated direct normal irradiance and percent diffuse irradiance are given as a reference to indicate the expected irradiance levels. This method can be applied to the calibration of photovoltaic reference cells. Graphic examples are provided for amorphous silicon and monocrystalline silicon solar cells under direct normal and global normal solar irradiances.

Mueller, Robert L.

1987-01-01

387

Development of a shingle-type solar cell module  

NASA Technical Reports Server (NTRS)

The development of a solar cell module, which is suitable for use in place of shingles on the sloping roofs of residental or commercial buildings, is reported. The design consists of nineteen series-connected 53 mm diameter solar cells arranged in a closely packed hexagon configuration. The shingle solar cell module consists of two basic functional parts: an exposed rigid portion which contains the solar cell assembly, and a semi-flexible portion which is overlapped by the higher courses of the roof installation. Consideration is given to the semi-flexible substrate configuration and solar cell and module-to-module interconnectors. The results of an electrical performance analysis are given and it is noted that high specific power output can be attributed to the efficient packing of the circular cells within the hexagon shape. The shingle should function for at least 15 years, with a specific power output of 98 W/sq w.

Shepard, N. F., Jr.; Sanchez, L. E.

1978-01-01

388

High saturation solar light beam induced current scanning of solar cells.  

PubMed

The response of the electrical parameters of photovoltaic cells under concentrated solar irradiance has been the subject of many studies performed in recent times. The high saturation conditions typically found in solar cells that are subjected to highly concentrated solar radiation may cause electrically active cell features to behave differently than under monochromatic laser illumination, normally used in light beam induced current (LBIC) investigations. A high concentration solar LBIC (S-LBIC) measurement system has been developed to perform localized cell characterization. The responses of silicon solar cells that were measured qualitatively include externally biased induced cell current at specific cell voltages, I(V), open circuit voltage, V(oc), and the average rate of change of the cell bias with the induced current, DeltaV/DeltaI(V), close to the zero bias region. These images show the relative scale of the parameters of a cell up to the penetration depth of the solar beam and can be obtained with relative ease, qualifying important electrical response features of the solar cell. The S-LBIC maps were also compared with maps that were similarly obtained using a high intensity He-Ne laser beam probe. This article reports on the techniques employed and initial results obtained. PMID:17503930

Vorster, F J; van Dyk, E E

2007-01-01

389

Chemical and electronic characterization of copper indium gallium diselenide thin film solar cells and correlation of these characteristics to solar cell operation  

Microsoft Academic Search

This dissertation embodies solid state physics research to understand the basic physical mechanisms underlying the movement of charge inside solar cells, in particular, the high efficiency copper indium gallium diselenide (CIGS) solar cell. The fundamental physics of the operation of these complex polycrystalline alloys remains incompletely understood. CIGS based solar cells have obtained conversion efficiencies of nearly 20%. Solar cells

Michael Justin Hetzer

2009-01-01

390

More About V-Grooved GaAs Solar Cells  

NASA Technical Reports Server (NTRS)

NASA technical memorandum presents additional information about experimental devices described in "V-Grooved GaAs Solar Cell" (LEW-14954). Experimental V-groove cells exhibited improved optical coupling and greater short-circuit current.

Bailey, S. G.; Wilt, D. M.; Landis, G. A.; Thomas, R. D.; Fatemi, N.

1993-01-01

391

Thermodynamics, Entropy, Information and the Efficiency of Solar Cells  

E-print Network

modeled as another, parallel, circuit where the inputof the parallel processes is quite common in circuit theory.circuit that the solar cell utilizes, whether placing the cells in series or in parallel,

Abrams, Zeev R.

2012-01-01

392

Infrared Reflective and Transparent Inverted Metamorphic Triple Junction Solar Cells  

Microsoft Academic Search

The infrared (IR) portion of the solar spectrum with photon energies below the lowest bandgap in III-V multijunction photovoltaic devices does not contribute to electrical power and is typically ignored during solar cell design. In a three junction inverted metamorphic multijunction (IMM) solar cell with a 1.0 eV bottom junction, this infrared light makes up 16% of the total power

John F. Geisz; J. Scott Ward; Anna Duda; Waldo Olavarria; Lynn Gedvilas; Michelle Young; Mark W. Wanlass; Jeff Carapella; Sarah R. Kurtz; Daniel J. Friedman; Manuel J. Romero; Myles A. Steiner

2010-01-01

393

Annealing characteristics of irradiated hydrogenated amorphous silicon solar cells  

NASA Technical Reports Server (NTRS)

It was shown that 1 MeV proton irradiation with fluences of 1.25E14 and 1.25E15/sq cm reduces the normalized I(sub SC) of a-Si:H solar cell. Solar cells recently fabricated showed superior radiation tolerance compared with cells fabricated four years ago; the improvement is probably due to the fact that the new cells are thinner and fabricated from improved materials. Room temperature annealing was observed for the first time in both new and old cells. New cells anneal at a faster rate than old cells for the same fluence. From the annealing work it is apparent that there are at least two types of defects and/or annealing mechanisms. One cell had improved I-V characteristics following irradiation as compared to the virgin cell. The work shows that the photothermal deflection spectroscopy (PDS) and annealing measurements may be used to predict the qualitative behavior of a-Si:H solar cells. It was anticipated that the modeling work will quantitatively link thin film measurements with solar cell properties. Quantitative predictions of the operation of a-Si:H solar cells in a space environment will require a knowledge of the defect creation mechanisms, defect structures, role of defects on degradation, and defect passivation and annealing mechanisms. The engineering data and knowledge base for justifying space flight testing of a-Si:H alloy based solar cells is being developed.

Payson, J. S.; Abdulaziz, S.; Li, Y.; Woodyard, J. R.

1991-01-01

394

Solar power system and high efficiency photovoltaic cells used therein  

Microsoft Academic Search

A solar power system is disclosed including a movable platform for tracking the sun, a radiation concentrator, and a plurality of photovoltaic cell modules positioned on the platform for receiving concentrated solar radiation. The module includes a heat dissipation housing which supports a silicon cell across an open end of the housing. A heat transfer block physically engages the silicon

T. I. Chappell; R. M. White

1980-01-01

395

Photovoltaic Measurements in Single-Nanowire Silicon Solar Cells  

E-print Network

Photovoltaic Measurements in Single-Nanowire Silicon Solar Cells Michael D. Kelzenberg, Daniel B-voltage measurements were made under simulated Air Mass 1.5 global illumination. Photovoltaic spectral response that of wafer-based crystalline Si solar cells but at costs competitive with thin- film technologies. Previous

Atwater, Harry

396

CRADA Final Report: Process development for hybrid solar cells  

SciTech Connect

TCF funding of a CRADA between LBNL and RSLE leveraged RSLE's original $1M investment in LBNL research and led to development of a solar cell fabrication process that will bring the high efficiency, high voltage hybrid tandem solar cell closer to commercialization. RSLE has already built a pilot line at its Phoenix, Arizona site.

Ager, Joel W

2011-02-14

397

Initial test bed for Very High Efficiency Solar Cell  

Microsoft Academic Search

Very High Efficiency Solar Cell (VHESC) program is developing integrated optical systemphotovoltaic modules for portable applications that operate at greater than 50 percent efficiency. We are integrating the optical design with the solar cell design, and we have entered previously unoccupied design space [1]. A test bed for rapid development and verification of performance of subsystems is also being developed.

Allen Barnett; Xiaoting Wang; Nick Waite; Paola Murcia; Christiana Honsberg; Doug Kirkpatrick; Dan Laubacher; Fouad Kiamilev; Keith Goossen; Mark Wanlass; Myles Steiner; Richard Schwartz; Jeff Gray; Allen Gray; Paul Sharps; Keith Emery; Larry Kazmerski

2008-01-01

398

Review on upgrading efficiency of silicon solar battery cells  

Microsoft Academic Search

An overview of the study on upgrading efficiency of silicon solar battery cells is presented. Review on the following subjects was conducted to upgrade conversion efficiency of solar battery cells: (1) selection of silicon wafers paying attention to resistivity and production methods; (2) diffusion process, including passivation at the front and rear surfaces; (3) contact configurations between electrodes and silicon

Sumio Matsuda; Takashi Tamura; Masato Uesugi

1992-01-01

399

Silicon solar cell process development, fabrication, and analysis  

NASA Technical Reports Server (NTRS)

Two large cast ingots were evaluated. Solar cell performance versus substrate position within the ingots was obtained and the results are presented. Dendritic web samples were analyzed in terms of structural defects, and efforts were made to correlate the data with the performance of solar cells made from the webs.

Yoo, H. I.; Iles, P. A.; Leung, D. C.

1981-01-01

400

Design of Nanostructured Solar Cells Using Coupled Optical and Electrical Modeling  

E-print Network

Design of Nanostructured Solar Cells Using Coupled Optical and Electrical Modeling Michael G efficiency in solar cells. We use coupled optical and electrical modeling to guide optimization carriers are efficiently collected. KEYWORDS: Thin film solar cells, plasmon, nanophotonic, light trapping

Atwater, Harry

401

Core-Shell Nanopillar Array Solar Cells using Cadmium Sulfide Coating on Indium Phosphide Nanopillars  

E-print Network

tandem solar cell with 10.6% power conversion efficiency. ,picture of the power conversion efficiency of solar cells,solar cell under light. Source: National Instruments [57] The final power conversion efficiency (

Tu, Bor-An Clayton

2013-01-01

402

Block 2 solar cell module environmental test program  

NASA Technical Reports Server (NTRS)

Environmental tests were performed of on 76 solar cell modules produced by four different manufacturers. The following tests were performed: (1) 28 day temperature and humidity; (2) rain and icing; (3) salt fog; (4) sand and dust; (5) vacuum/steam/pressure; (6) fungus; (7) temperature/altitude; and (8) thermal shock. Environmental testing of the solar cell modules produced cracked cells, cracked encapsulant and encapsulant delaminations on various modules. In addition, there was some minor cell and frame corrosion.

Holloway, K. L.

1978-01-01

403

AlGaAs top solar cell for mechanical attachment in a multi-junction tandem concentrator solar cell stack  

NASA Technical Reports Server (NTRS)

Free-standing, transparent, tunable bandgap AlxGa1-xAs top solar cells have been fabricated for mechanical attachment in a four terminal tandem stack solar cell. Evaluation of the device results has demonstrated 1.80 eV top solar cells with efficiencies of 18 percent (100 X, and AM0) which would yield stack efficiencies of 31 percent (100 X, AM0) with a silicon bottom cell. When fully developed, the AlxGa1-xAs/Si mechanically-stacked two-junction solar cell concentrator system can provide efficiencies of 36 percent (AM0, 100 X). AlxGa1-xAs top solar cells with bandgaps from 1.66 eV to 2.08 eV have been fabricated. Liquid phase epitaxy (LPE) growth techniques have been used and LPE has been found to yield superior AlxGa1-xAs material when compared to molecular beam epitaxy and metal-organic chemical vapor deposition. It is projected that stack assembly technology will be readily applicable to any mechanically stacked multijunction (MSMJ) system. Development of a wide bandgap top solar cell is the only feasible method for obtaining stack efficiencies greater than 40 percent at AM0. System efficiencies of greater than 40 percent can be realized when the AlGaAs top solar cell is used in a three solar cell mechanical stack.

Dinetta, L. C.; Hannon, M. H.; Cummings, J. R.; Mcneeley, J. B.; Barnett, Allen M.

1990-01-01

404

Flexible, FEP-Teflon covered solar cell module development  

NASA Technical Reports Server (NTRS)

Techniques and equipment were developed for the large scale, low-cost fabrication of lightweight, roll-up and fold-up, FEP-Teflon encapsulated solar cell modules. Modules were fabricated by interconnecting solderless single-crystal silicon solar cells and heat laminating them at approximately 300 C between layers of optically clear FEP and to a loadbearing Kapton substrate sheet. Modules were fabricated from both conventional and wraparound contact solar cells. A heat seal technique was developed for mechanically interconnecting modules into an array. The electrical interconnections for both roll-up and fold-up arrays were also developed. The use of parallel-gap resistance welding, ultrasonic bonding, and thermocompression bonding processes for attaching interconnects to solar cells were investigated. Parallel-gap welding was found to be best suited for interconnecting the solderless solar cells into modules. Details of the fabrication equipment, fabrication processes, module and interconnect designs, environmental test equipment, and test results are presented.

Rauschenbach, H. S.; Cannady, M. D.

1976-01-01

405

High-Efficiency Solar Cell Concepts: Physics, Materials, and Devices  

SciTech Connect

Over the past three decades, significant progress has been made in the area of high-efficiency multijunction solar cells, with the effort primarily directed at current-matched solar cells in tandem. The key materials issues here have been obtaining semiconductors with the required bandgaps for sequential absorption of light in the solar spectrum and that are lattice matched to readily available substrates. The GaInP/GaAs/Ge cell is a striking example of success achieved in this area. Recently, several new approaches for high-efficiency solar cell design have emerged, that involve novel methods for tailoring alloy bandgaps, as well as alternate technologies for hetero-epitaxy of III-V's on Si. The advantages and difficulties expected to be encountered with each approach will be discussed, addressing both the materials issues and device physics whilst contrasting them with other fourth-generation solar cell concepts.

Mascarenhas, A.; Francoeur, S.; Seong, M. J.; Fluegel, B.; Zhang, Y.; Wanlass, M. W.

2005-01-01

406

Photochemical tissue bonding  

DOEpatents

Photochemical tissue bonding methods include the application of a photosensitizer to a tissue and/or tissue graft, followed by irradiation with electromagnetic energy to produce a tissue seal. The methods are useful for tissue adhesion, such as in wound closure, tissue grafting, skin grafting, musculoskeletal tissue repair, ligament or tendon repair and corneal repair.

Redmond, Robert W. (Brookline, MA); Kochevar, Irene E. (Charlestown, MA)

2012-01-10

407

PHOTOCHEMICAL REACTIVITY OF PERCHLOROETHYLENE  

EPA Science Inventory

Perchloroethylene (PCE), a solvent used in dry cleaning, has been suspected of contributing significantly to photochemical ozone/oxidant (O3/Ox) problems in urban atmospheres. Past evidence, however, was neither complete nor consistent. To interpret more conclusively the past evi...

408

Microbial Fuel Cells -Solar Times http://solar.rain-barrel.net/microbial-fuel-cells/ 1 of 3 6/28/2006 11:32 AM  

E-print Network

- PDF4Free v2.0 http://www.pdf4free.com #12;Microbial Fuel Cells - Solar Times http://solar.rain-barrel.net/microbial-fuel-cellsMicrobial Fuel Cells - Solar Times http://solar.rain-barrel.net/microbial-fuel-cells/ 1 of 3 6/28/2006 11:32 AM Microbial Fuel Cells Posted in Alternative Energy by admin. The other end of solar energy

Lovley, Derek

409

Silicon solar cells: Past, present and the future  

NASA Astrophysics Data System (ADS)

There has been a great demand for renewable energy for the last few years. However, the solar cell industry is currently experiencing a temporary plateau due to a sluggish economy and an oversupply of low-quality cells. The current situation can be overcome by reducing the production cost and by improving the cell is conversion efficiency. New materials such as compound semiconductor thin films have been explored to reduce the fabrication cost, and structural changes have been explored to improve the cell's efficiency. Although a record efficiency of 24.7% is held by a PERL structured silicon solar cell and 13.44% has been realized using a thin silicon film, the mass production of these cells is still too expensive. Crystalline and amorphous silicon based solar cells have led the solar industry and have occupied more than half of the market so far. They will remain so in the future photovoltaic (PV) market by playing a pivotal role in the solar industry. In this paper, we discuss two primary approaches that may boost the silicon based solar cell market; one is a high efficiency approach and the other is a low cost approach. We also discuss the future prospects of various solar cells.

Lee, Youn-Jung; Kim, Byung-Sung; Ifitiquar, S. M.; Park, Cheolmin; Yi, Junsin

2014-08-01

410

Silicon Solar Cell Process Development, Fabrication and Analysis  

NASA Technical Reports Server (NTRS)

Ribbon to Ribbon (RTR) solar cells processed from polycrystalline feedstock showed maximum AMO efficiency of 5.6%. Solar cells from single crystalline feedstock showed slightly higher efficiency than those from polycrystalline feedstock, indicating maximum efficiency of about 6.6% with SiO AR coating. Single crystalline control cells gave 11-12% AMO efficiencies demonstrating that the poor performance of the RTR solar was due to the low quality of material itself. Dendritic web solar cells from the standard process showed maximum AMO efficiency of 9.8% while efficiency of control solar cells were around 11-12%. Web solar cells from back surface field (BSF) process indicated maximum AMO efficiency of 10.9%. Some improvement in open circuit voltage was noticed from the BSF process. Small light spot scanning experiments were carried out on the solar cells from Wacker Silso, EFG, RTR, and dendritic web ribbons. Photoresponse results provided information on localized cell performance and grain size in polycrystalline material, and agreed quite well with the cell performance data, such as efficiency, minority carrier diffusion length, and spectral response.

Yoo, H. I.; Iles, P. A.; Tanner, D. P.

1978-01-01

411

Wearable solar cells by stacking textile electrodes.  

PubMed

A new and general method to produce flexible, wearable dye-sensitized solar cell (DSC) textiles by the stacking of two textile electrodes has been developed. A metal-textile electrode that was made from micrometer-sized metal wires was used as a working electrode, while the textile counter electrode was woven from highly aligned carbon nanotube fibers with high mechanical strengths and electrical conductivities. The resulting DSC textile exhibited a high energy conversion efficiency that was well maintained under bending. Compared with the woven DSC textiles that are based on wire-shaped devices, this stacked DSC textile unexpectedly exhibited a unique deformation from a rectangle to a parallelogram, which is highly desired in portable electronics. This lightweight and wearable stacked DSC textile is superior to conventional planar DSCs because the energy conversion efficiency of the stacked DSC textile was independent of the angle of incident light. PMID:24789065

Pan, Shaowu; Yang, Zhibin; Chen, Peining; Deng, Jue; Li, Houpu; Peng, Huisheng

2014-06-10

412

Efficiency of silicon solar cells containing chromium  

DOEpatents

Efficiency of silicon solar cells containing about 10.sup.15 atoms/cm.sup.3 of chromium is improved about 26% by thermal annealing of the silicon wafer at a temperature of 200.degree. C. to form chromium precipitates having a diameter of less than 1 Angstrom. Further improvement in efficiency is achieved by scribing laser lines onto the back surface of the wafer at a spacing of at least 0.5 mm and at a depth of less than 13 micrometers to preferentially precipitate chromium near the back surface and away from the junction region of the device. This provides an economical way to improve the deleterious effects of chromium, one of the impurities present in metallurgical grade silicon material.

Frosch, Robert A. Administrator of the National Aeronautics and Space (New Port Beach, CA); Salama, Amal M. (New Port Beach, CA)

1982-01-01

413

Contact formation in gallium arsenide solar cells  

NASA Technical Reports Server (NTRS)

Gold and gold-based alloys, commonly used as solar cell contact materials, are known to react readily with gallium arsenide. Experiments were performed to identify the mechanisms involved in these GaAs-metal interactions. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are explained by invoking this mechanism.

Weizer, Victor G.; Fatemi, Navid S.

1988-01-01

414

Interface mechanisms in CIGS solar cells  

NASA Astrophysics Data System (ADS)

The role of Ga in CIGS solar cells is complex. In addition to its primary role of alloying agent to increase the band gap we also observe its influence on passivation, transport, trapping and doping. At low levels it can positively influence all of these mechanisms and improve performance. As its level is increased, there are complex tradeoffs among these that must be controlled to maintain good performance. We have applied photocapacitance techniques to study the junction interface region and the role that Ga plays in its formation and operation. We observe a correlation between the defect that provides doping and the recombination centers, which control Voc. The dominant centers are deep in the band gap and are located near the metallurgical junction. It is proposed that a reduction of the correlated doping defect will result in improved interface properties.

Jayapayalan, A.; Sankaranarayanan, H.; Shankaradas, M.; Panse, P.; Narayanaswamy, R.; Ferekides, C. S.; Morel, D. L.

1999-03-01

415

Comprehensive silicon solar cell computer modeling  

NASA Technical Reports Server (NTRS)

The development of an efficient, comprehensive Si solar cell modeling program that has the capability of simulation accuracy of 5 percent or less is examined. A general investigation of computerized simulation is provided. Computer simulation programs are subdivided into a number of major tasks: (1) analytical method used to represent the physical system; (2) phenomena submodels that comprise the simulation of the system; (3) coding of the analysis and the phenomena submodels; (4) coding scheme that results in efficient use of the CPU so that CPU costs are low; and (5) modularized simulation program with respect to structures that may be analyzed, addition and/or modification of phenomena submodels as new experimental data become available, and the addition of other photovoltaic materials.

Lamorte, M. F.

1984-01-01

416

Solar cells incorporating light harvesting arrays  

DOEpatents

A solar cell incorporates a light harvesting array that comprises: (a) a first substrate comprising a first electrode; and (b) a layer of light harvesting rods electrically coupled to the first electrode, each of the light harvesting rods comprising a polymer of Formula I: X.sup.1.paren open-st.X.sup.m+1).sub.m (I) wherein m is at least 1, and may be from two, three or four to 20 or more; X.sup.1 is a charge separation group (and preferably a porphyrinic macrocycle, which may be one ligand of a double-decker sandwich compound) having an excited-state of energy equal to or lower than that of X.sup.2 ; and X.sup.2 through X.sup.m+1 are chromophores (and again are preferably porphyrinic macrocycles).

Lindsey, Jonathan S. (Raleigh, NC); Meyer, Gerald J. (Baltimore, MD)

2002-01-01

417

Method of manufacturing a solar cell  

SciTech Connect

A method of manufacturing a solar cell comprising a silicon disc having a region of the n-conductivity type adjoining a major surface, in which an electrode containing silver is provided on the n-type region by means of a silk-screening process, characterized in that during the silk-screening process a paste is used which, in addition to silver, contains an addition in an elementary form, which addition belongs to the group of elements consisting of bismuth, magnesium and indium, that after providing the electrode a thermal treatment in an oxidizing atmosphere is carried out, and that the electrode is then subjected to a chemical or mechanical treatment to improve the junction resistance with the silicon.

van Mourik, J.H.C.

1982-06-22

418

Laser-assisted solar cell metallization processing  

NASA Technical Reports Server (NTRS)

The status of the laser-assisted solar cell metallization processing is described. Metallo-organic silver films were spun-on by argon ion laser beam pyrolysis. The metallo-organic decomposition (MOD) film was spun-on an evaporated Ti/Pd film to produce tood adhesion. In a maskless process, the argon ion laser writes the contact pattern. The film is then built up to obtain the required conductivity using conventional silverplating process. The Ti/Pd film in the field is chemically etched using the plated silver film as the mask. The width of the contact pattern is determined by the power of the laser. Widths as thin as 20 microns were obtained using 0.66 W of laser power. Cells fabricated with the 50 micron line widths of 4 ohm-cm floating zone (Fz) silicon-produced efficiencies of 16.6% (no passivation) which were equivalent to the best cells using conventional metallization/lithography and no passivation.

Meier, D. L.

1986-01-01

419

10 ?? 10 cm2 Hit Solar Cells Contacted with Lead-Free Electrical Conductive Adhesives to Solar Cell Interconnectors  

Microsoft Academic Search

In the present study we have investigated the optical and electrical properties of 10 ?? 10 cm2 HIT solar cells with evaporated Cr\\/Ag grids. Contacts were done with low temperature lead-free electrically conductive adhesives to standard solar cell interconnector tabs (IT). Compared to solder joints conductive adhesives have the advantage of lower contact formation temperature with reasonable low contact resistances

M. L. D. Scherff; S. Schwertheim; Yue Ma; T. Mueller; W. R. Fahrner

2006-01-01

420

Method of making quasi-grain boundary-free polycrystalline solar cell structure and solar cell structure obtained thereby  

Microsoft Academic Search

A new solar cell structure is provided which will increase the efficiency of polycrystalline solar cells by suppressing or completely eliminating the recombination losses due to the presence of grain boundaries. This is achieved by avoiding the formation of the p-n junction (or other types of junctions) in the grain boundaries and by eliminating the grain boundaries from the active

F. N. Gonzalez; A. Neugroschel

1984-01-01

421

Comparative modeling of InP solar cell structures  

NASA Technical Reports Server (NTRS)

The comparative modeling of p(+)n and n(+)p indium phosphide solar cell structures is studied using a numerical program PC-1D. The optimal design study has predicted that the p(+)n structure offers improved cell efficiencies as compared to n(+)p structure, due to higher open-circuit voltage. The various cell material and process parameters to achieve the maximum cell efficiencies are reported. The effect of some of the cell parameters on InP cell I-V characteristics was studied. The available radiation resistance data on n(+)p and p(+)p InP solar cells are also critically discussed.

Jain, R. K.; Weinberg, I.; Flood, D. J.

1991-01-01

422

Spectral splitting planar solar concentrator: experimental testing of a design aiming at dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

We present a new solar concentrator concept. This concept is based on spectral splitting. It implies reflective, refractive and diffractive elements that allow two spectrally differentiated beams to reach different and/or unmatched lattice solar cells. The aimed geometrical concentration factor is 5 and the theoretical optical efficiency of that concentrator concept reaches theoretically 82%. The following study will discuss the concept of such a solar concentrator. A practical application to dye sensitized solar cells is given. The manufacturing and design of the element is then exposed. Those elements have been tested in the laboratory. Good agreements with theoretical simulations are demonstrated.

Blain, P.; Michel, C.; Clermont, L.; Languy, F.; Dcultot, M.; Habraken, Serge; Lenaerts, C.; Fleury-Frenette, K.; Vandormael, D.; Loicq, Jrme J. D.

2014-05-01

423

Evaluation of solar cells and arrays for potential solar power satellite applications  

NASA Technical Reports Server (NTRS)

Proposed solar array designs and manufacturing methods are evaluated to identify options which show the greatest promise of leading up to the develpment of a cost-effective SPS solar cell array design. The key program elements which have to be accomplished as part of an SPS solar cell array development program are defined. The issues focussed on are: (1) definition of one or more designs of a candidate SPS solar array module, using results from current system studies; (2) development of the necessary manufacturing requirements for the candidate SPS solar cell arrays and an assessment of the market size, timing, and industry infrastructure needed to produce the arrays for the SPS program; (3) evaluation of current DOE, NASA and DOD photovoltaic programs to determine the impacts of recent advances in solar cell materials, array designs and manufacturing technology on the candidate SPS solar cell arrays; and (4) definition of key program elements for the development of the most promising solar cell arrays for the SPS program.

Almgren, D. W.; Csigi, K.; Gaudet, A. D.

1978-01-01

424

Controlling radiative loss in quantum well solar cells  

NASA Astrophysics Data System (ADS)

The inclusion of quantum well layers in a solar cell provides a means for extending the absorption and therefore increasing the photocurrent of the cell. In 2009, a single-junction GaAsP/InGaAs quantum well solar cell attained a peak efficiency of 28.3% under solar concentration. Since then InGaP/MQW/Ge quantum well devices have attained efficiencies in excess of 40% under concentration and over 30% under AM0. The principle motivation for incorporating a quantum well stack into a multi-junction solar cell is to increase the photocurrent delivered by the middle junction over the conventional In0.01GaAs bulk junction. This enables additional current to flow through the top and middle cells, resulting in a sharp rise in efficiency. However, quantum wells also provide some freedom to manipulate the radiative recombination in the quantum well solar cell. We show that under radiatively dominated, anisotropic emission, strong radiative coupling between sub-cells takes place, resulting in a multi-junction solar cell that is tolerant to daily and seasonal changes to the solar spectrum.

Ekins-Daukes, N. J.; Lee, K.-H.; Hirst, L.; Chan, A.; Fhrer, M.; Adams, J.; Browne, B.; Barnham, K. W. J.; Stavrinou, P.; Connolly, J.; Roberts, J. S.; Stevens, B.; Airey, R.; Kennedy, K.

2013-07-01

425

SLAM examination of solar cells and solar cell welds. [Scanning Laser Acoustic Microscope  

NASA Technical Reports Server (NTRS)

The scanning laser acoustic microscope (SLAM) has been evaluated for non-destructive examination of solar cells and interconnector bonds. Using this technique, it is possible to view through materials in order to reveal regions of discontinuity such as microcracks and voids. Of particular interest is the ability to evaluate, in a unique manner, the bonds produced by parallel gap welding. It is possible to not only determine the area and geometry of the bond between the tab and cell, but also to reveal any microcracks incurred during the welding. By correlating the SLAM results with conventional techniques of weld evaluation a more confident weld parameter optimization can be obtained.

Stella, P. M.; Vorres, C. L.; Yuhas, D. E.

1981-01-01

426

Semitransparent organic solar cells with organic wavelength dependent reflectors  

NASA Astrophysics Data System (ADS)

Semitransparent organic solar cells employing solution-processable organic wavelength dependent reflectors of chiral nematic (cholesteric) liquid crystals are demonstrated. The cholesteric liquid crystal (CLC) reflects only in a narrow band of the solar spectrum and remains transparent for the remaining wavelengths. The reflective band is matched to the absorption spectrum of the organic solar cell such that only unabsorbed photons that can contribute to the photocurrent are reflected to pass through the active layer a second time. In this way, the efficiency of semitransparent organic solar cells can be enhanced without significant transparency losses. An efficiency increase of 6% was observed when a CLC reflector with a reflection band of 540-620 nm was used, whereas the transparency of the organic solar cells is only suppressed in the 80 nm narrow bandwidth.

Galagan, Yulia; Debije, Michael G.; Blom, Paul W. M.

2011-01-01

427

Periodic nano/micro-hole array silicon solar cell  

PubMed Central

In this study, we applied a metal catalyst etching method to fabricate a nano/microhole array on a Si substrate for application in solar cells. In addition, the surface of an undesigned area was etched because of the attachment of metal nanoparticles that is dissociated in a solution. The nano/microhole array exhibited low specular reflectance (<1%) without antireflection coating because of its rough surface. The solar spectrum related total reflection was approximately 9%. A fabricated solar cell with a 40-?m hole spacing exhibited an efficiency of 9.02%. Comparing to the solar cell made by polished Si, the external quantum efficiency for solar cell with 30s etching time was increased by 16.7%. PMID:25520601

2014-01-01

428

Tool permits damage-free removal of solar cell  

NASA Technical Reports Server (NTRS)

Modified soldering iron extracts a wrap-around solar cell that is attached with solder or adhesive to a substrate without destroying the cell removed or damaging adjacent cells. Heat, vacuum, and compressed air, operated from a special head attached to the soldering iron, loosen, extract, and protect the cell.

Beckley, J. E., Jr.

1966-01-01

429

Process development for high-efficiency silicon solar cells  

SciTech Connect

Fabrication of high-efficiency silicon solar cells in an industrial environment requires a different optimization than in a laboratory environment. Strategies are presented for process development of high-efficiency silicon solar cells, with a goal of simplifying technology transfer into an industrial setting. The strategies emphasize the use of statistical experimental design for process optimization, and the use of baseline processes and cells for process monitoring and quality control. 8 refs.

Gee, J.M.; Basore, P.A.; Buck, M.E.; Ruby, D.S.; Schubert, W.K.; Silva, B.L.; Tingley, J.W.

1991-12-31

430

Local optical and electric characteristics of solar cells  

Microsoft Academic Search

Today photovoltaic cells are divided into two principal types: higher-efficiency but quite expensive crystalline silicon solar cells (either monocrystalline or multicrystalline), and lower-cost thin-film solar cells, usually composed of amorphous silicon, polycrystalline silicon, cadmium telluride, or copper indium gallium diselenide. In both cases their operation is based on a large-area pn junction. Their efficiency is generally limited by defects and

Pavel Tomnek; Pavel Skarvada; Lubomr Grmela

2009-01-01

431

Development of a new integral solar cell protective cover  

NASA Technical Reports Server (NTRS)

A unique polyimide polymer has been developed which shows promise as an encapsulant for interconnected solar cell modules. Such an integral cover offers important weight and cost advantages. The polymer has been characterized on silicon solar cells with respect to electrical output and spectral response. The response of the material-coated cells to electron, low-energy proton, and vacuum-ultraviolet radiation, thermal shock and humidity tests was determined.

Naselow, A. B.; Dupont, P. S.; Scott-Monck, J.

1983-01-01

432

Studies of Sputtered Cadmium Telluride and Cadmium Selenide Solar Cells  

NASA Astrophysics Data System (ADS)

CdTe has recently become the most commercially successful polycrystalline thinfilm solar module material. Its low cost, large-area solar module is reshaping the silicondominated solar panel market; however, CdTe has much room to improve and thus more fundamental understanding is needed. Current thin film solar cell research is focused on two areas: One is identifying loss mechanisms and understanding the polycrystalline nature of single junction device to improve device performance. Another is searching for new materials and fabricating tandem solar cells. In this study, along with other people's work to improve the efficiency of CdTe solar module, I studied loss mechanism and growth mode of CdTe solar cells to have fundamental understanding of polycrystalline films. In addition to that, in an effort to make tandem solar cells, I fabricated and characterized CdSe solar cells, which is considered as an ideal candidate for the top cell with its band gap of 1.7 eV. This dissertation is designed to show similarities and differences between CdTe and CdSe solar cells, side by side. After the introduction (Chapter1), I will review the physical properties of CdTe and CdSe solar cells (Chapter 2). Two primary tools to study defects and surface morphology were photoluminescence (PL) and atomic force microscopy (AFM). PL showed information on the crystallinity and defects of CdTe and CdSe films before and after annealing.(Chapter 3). AFM measurements and their analysis using scaling theory revealed information on the growth modes of CdTe and CdSe films.(Chapter 4). With the goal of exploring suitability for tandem structures with 1.7 eV top cell and 1.1 eV bottom cell, I fabricated and characterized single-junction CdSe devices. (Chapter 5) In addition, for the bottom cell I fabricated HgCdTe cells with Eg1.1 eV. Single junction HgCdTe and two-terminal CdTe/HgCdTe tandem solar cells were fabricated and characterized. (Chapter 5)

Kwon, Dohyoung

433

Advancing tandem solar cells by spectrally selective multilayer intermediate reflectors.  

PubMed

Thin-film silicon tandem solar cells are composed of an amorphous silicon top cell and a microcrystalline silicon bottom cell, stacked and connected in series. In order to match the photocurrents of the top cell and the bottom cell, a proper photon management is required. Up to date, single-layer intermediate reflectors of limited spectral selectivity are applied to match the photocurrents of the top and the bottom cell. In this paper, we design and prototype multilayer intermediate reflectors based on aluminum doped zinc oxide and doped microcrystalline silicon oxide with a spectrally selective reflectance allowing for improved current matching and an overall increase of the charge carrier generation. The intermediate reflectors are successfully integrated into state-of-the-art tandem solar cells resulting in an increase of overall short-circuit current density by 0.7 mA/cm(2) in comparison to a tandem solar cell with the standard single-layer intermediate reflector. PMID:25322181

Hoffmann, Andre; Paetzold, Ulrich W; Zhang, Chao; Merdzhanova, Tsvetelina; Lambertz, Andreas; Ulbrich, Carolin; Bittkau, Karsten; Rau, Uwe

2014-08-25

434

Development of high-performance GaInAsP solar cells for tandem solar cell applications  

NASA Technical Reports Server (NTRS)

Recent results in the development of high-efficiency, low-bandgap GaInAsP solar cells epitaxially grown and lattice matched on InP substrates are presented. Such cells are intended to be used as optimum bottom cell components in tandem solar cells. Assuming that a GaAs-based top cell is used, computer simulation of the potential bottom cell performance as a function of the cell bandgap and incident spectrum indicates that two particular alloys are desirable: Ga0.47In0.53As (Eg = 0.75 eV) for space applications and Ga0.25In0.75As0.54P0.46 (Eg = 0.95 eV) for terrestrial applications. In each of these materials, solar cells with new record-level efficiencies have been fabricated. The efficiency boost available to tandem configurations from these low-bandgap cells is discussed.

Wanlass, M. W.; Ward, J. S.; Gessert, T. A.; Emery, K. A.; Horner, G. S.

1990-01-01

435

Indium Phosphide Window Layers for Indium Gallium Arsenide Solar Cells  

NASA Technical Reports Server (NTRS)

Window layers help in reducing the surface recombination at the emitter surface of the solar cells resulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (In(x)Ga(1-x)As) and related materials based solar cells are quite promising for photovoltaic and thermophotovoltaic applications. The flexibility of the change in the bandgap energy and the growth of InGaAs on different substrates make this material very attractive for multi-bandgap energy, multi-junction solar cell approaches. The high efficiency and better radiation performance of the solar cell structures based on InGaAs make them suitable for space power applications. This work investigates the suitability of indium phosphide (InP) window layers for lattice-matched In(0.53)Ga(0.47)As (bandgap energy 0.74 eV) solar cells. We present the first data on the effects of the p-type InP window layer on p-on-n lattice-matched InGaAs solar cells. The modeled quantum efficiency results show a significant improvement in the blue region with the InP window. The bare InGaAs solar cell performance suffers due to high surface recombination velocity (10(exp 7) cm/s). The large band discontinuity at the InP/InGaAs heterojunction offers a great potential barrier to minority carriers. The calculated results demonstrate that the InP window layer effectively passivates the solar cell front surface, hence resulting in reduced surface recombination and therefore, significantly improving the performance of the InGaAs solar cell.

Jain, Raj K.

2005-01-01

436

Metal-black scattering centers to enhance light harvesting by thin-film solar cells  

E-print Network

in efficiency at the maximum power point, were observed. 1. Introduction Thin film solar cells offer. The solar cell efficiency was determined both as a function of wavelength and for a solar spectrum produced have been shown to increase solar cell efficiency, at least in part of the solar spectrum depending

Peale, Robert E.

437

Photochemical isotope separation  

DOEpatents

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM); Boyer, Keith (Los Alamos, NM)

1987-01-01

438

Photochemical isotope separation  

DOEpatents

A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

1987-04-28

439

Solar cells. High-efficiency solution-processed perovskite solar cells with millimeter-scale grains.  

PubMed

State-of-the-art photovoltaics use high-purity, large-area, wafer-scale single-crystalline semiconductors grown by sophisticated, high-temperature crystal growth processes. We demonstrate a solution-based hot-casting technique to grow continuous, pinhole-free thin films of organometallic perovskites with millimeter-scale crystalline grains. We fabricated planar solar cells with efficiencies approaching 18%, with little cell-to-cell variability. The devices show hysteresis-free photovoltaic response, which had been a fundamental bottleneck for the stable operation of perovskite devices. Characterization and modeling attribute the improved performance to reduced bulk defects and improved charge carrier mobility in large-grain devices. We anticipate that this technique will lead the field toward synthesis of wafer-scale crystalline perovskites, necessary for the fabrication of high-efficiency solar cells, and will be applicable to several other material systems plagued by polydispersity, defects, and grain boundary recombination in solution-processed thin films. PMID:25635093

Nie, Wanyi; Tsai, Hsinhan; Asadpour, Reza; Blancon, Jean-Christophe; Neukirch, Amanda J; Gupta, Gautam; Crochet, Jared J; Chhowalla, Manish; Tretiak, Sergei; Alam, Muhammad A; Wang, Hsing-Lin; Mohite, Aditya D

2015-01-30

440

Effect of copper impurity on polycrystalline silicon solar cells  

NASA Technical Reports Server (NTRS)

The presence of copper impurity, up to 10 to the 15th atoms/cc, in single crystal silicon has been shown to have no deleterious effect on the p-n junction solar cell performance. However, in polycrystalline silicon, copper atoms tend to migrate to the defect sites because of the structural sensitive properties of copper. This study was undertaken to investigate the influence of this behavior of copper impurity on the performance of p-n junction solar cells fabricated from structurally imperfect silicon. Two sets of polycrystalline silicon substrates containing copper were examined. In one set of samples, copper was incorporated during growth, whereas in the other, copper was diffused. Solar cells were fabricated on both the sets of substrates by a standard process. Dark and light I-V and spectral response characteristics of the cells were measured and compared with copper-free polycrystalline silicon solar cells. The results and the model are discussed.

Daud, T.; Koliwad, K. M.

1978-01-01

441

GaAs solar cells for space applications  

NASA Technical Reports Server (NTRS)

GaAs solar cells offer substantial advantages for space photovoltaic power over Si solar cells in the areas of efficiency, elevated temperature operation, and radiation damage stability. A mission cost comparison is made for GaAs and Si solar cells. For Si cell arrays, the total mission cost is found to be a minimum for a solar concentration of 2.9. For GaAs, modes of operation and construction are investigated. Modes having lower mission costs than the minimum Si mission cost are defined. These include higher concentrations, lightweight cells, and simultaneous power generation and annealing. The technological progress necessary for GaAs to operate in these modes is identified.

Conway, E. J.; Walker, G. H.; Heinbockel, J. H.

1980-01-01

442

Response of silicon solar cell to pulsed laser illumination  

NASA Technical Reports Server (NTRS)

The response of silicon solar cell(s) to pulsed laser illumination is discussed. The motivation was due to the interest of Earth to space/Moon power beaming applications. When this work began, it was not known if solar cells would respond to laser light with pulse lengths in the nanosecond range and a repetition frequency in the kHz range. This is because the laser pulse would be shorter than the minority carrier lifetime of silicon. A 20-nanosecond (ns) full width half max (FWHM) pulse from an aluminum-gallium/arsenide (Al-Ga-As) diode laser was used to illuminate silicon solar cells at a wavelength of 885 nanometers (nm). Using a high-speed digital oscilloscope, the response of the solar cells to individual pulses across various resistive loads was observed and recorded.

Willowby, D.; Alexander, D.; Edge, T.; Herren, K.

1993-01-01

443

Accelerated aging of GaAs concentrator solar cells  

NASA Astrophysics Data System (ADS)

An accelerated aging study of AlGaAs/GaAs solar cells was completed. The purpose was to identify the possible degradation mechanisms of AlGaAs/GaAs solar cells in terrestrial applications. Thermal storage tests and accelerated AlGaAs corrosion studies were performed to provide an experimental basis for a statistical analysis of the estimated lifetime. Results of this study suggest that a properly designed and fabricated AlGaAs/GaAs solar cell can be mechanically rugged and environmentally stable with projected lifetimes exceeding 100 years.

Gregory, P. E.

1982-04-01

444

Accelerated aging of GaAs concentrator solar cells  

SciTech Connect

An accelerated aging study of AlGaAs/GaAs solar cells has been completed. The purpose of the study was to identify the possible degradation mechanisms of AlGaAs/GaAs solar cells in terrestrial applications. Thermal storage tests and accelerated AlGaAs corrosion studies were performed to provide an experimental basis for a statistical analysis of the estimated lifetime. Results of this study suggest that a properly designed and fabricated AlGaAs/GaAs solar cell can be mechanically rugged and environmentally stable with projected lifetimes exceeding 100 years.

Gregory, P.E.

1982-04-01

445

Neural Network Modeling of Degradation of Solar Cells  

SciTech Connect

Neural network modeling has been used to predict the degradation in conversion efficiency of solar cells in this work. The model takes intensity of light, temperature and exposure time as inputs and predicts the conversion efficiency of the solar cell. Backpropagation algorithm has been used to train the network. It is found that the neural network model satisfactorily predicts the degradation in efficiency of the solar cell with exposure time. The error in the computed results, after comparison with experimental results, lies in the range of 0.005-0.01, which is quite low.

Gupta, Himanshu; Ghosh, Bahniman [Department of Electrical Engineering, Indian Institute of Technology, Kanpur, 208016 (India); Banerjee, Sanjay K. [Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, TX, 78758 (United States)

2011-05-25

446

UV radiation hardness of silicon inversion layer solar cells  

NASA Astrophysics Data System (ADS)

For full utilization of the high spectral response of inversion-layer solar cells in the very-short-wavelength range of the solar spectrum, sufficient ultraviolet-radiation hardness is required. In addition to the charge-induced passivation achieved by incorporating cesium into the silicon nitride AR coating, the following means for further drastic reduction of UV-light-induced effects in inversion-layer solar cells without encapsulation are introduced and interpretations are given: increasing the nitride deposition temperature, silicon surface oxidation at low temperatures, texture etching, and using higher substrate resistivities. High UV radiation tolerance and improvement of the cell efficiency can be obtained simultaneously.

Hezel, R.

447

Applications of atomic layer deposition in solar cells.  

PubMed

Atomic layer deposition (ALD) provides a unique tool for the growth of thin films with excellent conformity and thickness control down to atomic levels. The application of ALD in energy research has received increasing attention in recent years. In this review, the versatility of ALD in solar cells will be discussed. This is specifically focused on the fabrication of nanostructured photoelectrodes, surface passivation, surface sensitization, and band-structure engineering of solar cell materials. Challenges and future directions of ALD in the applications of solar cells are also discussed. PMID:25604730

Niu, Wenbin; Li, Xianglin; Karuturi, Siva Krishna; Fam, Derrick Wenhui; Fan, Hongjin; Shrestha, Santosh; Wong, Lydia Helena; Tok, Alfred Iing Yoong

2015-02-13

448

Applications of atomic layer deposition in solar cells  

NASA Astrophysics Data System (ADS)

Atomic layer deposition (ALD) provides a unique tool for the growth of thin films with excellent conformity and thickness control down to atomic levels. The application of ALD in energy research has received increasing attention in recent years. In this review, the versatility of ALD in solar cells will be discussed. This is specifically focused on the fabrication of nanostructured photoelectrodes, surface passivation, surface sensitization, and band-structure engineering of solar cell materials. Challenges and future directions of ALD in the applications of solar cells are also discussed.

Niu, Wenbin; Li, Xianglin; Krishna Karuturi, Siva; Wenhui Fam, Derrick; Fan, Hongjin; Shrestha, Santosh; Wong, Lydia Helena; Iing Yoong Tok, Alfred

2015-02-01

449

Solar Energy Materials & Solar Cells 71 (2002) 511522 In situ Raman spectroscopy of the  

E-print Network

Solar Energy Materials & Solar Cells 71 (2002) 511­522 In situ Raman spectroscopy with the partial reduction of the WO3-framework, resulting in W5+ species in a background of W6+ sites. In this situation, a low energy excitation (e.g. visible light) is needed to excite an electron to a neighboring

Nabben, Reinhard

450

High-Efficiency, Multijunction Solar Cells for Large-Scale Solar Electricity Generation  

Microsoft Academic Search

A solar cell with an infinite number of materials (matched to the solar spectrum) has a theoretical efficiency limit of 68%. If sunlight is concentrated, this limit increases to about 87%. These theoretical limits are calculated using basic physics and are independent of the details of the materials. In practice, the challenge of achieving high efficiency depends on identifying materials

Sarah Kurtz

2006-01-01

451

Space Qualification Test of a-Silicon Solar Cell Modules  

NASA Technical Reports Server (NTRS)

The basic requirements of solar cell modules for space applications are generally described in MIL-S-83576 for the specific needs of the USAF. However, the specifications of solar cells intended for use on space terrestrial applications are not well defined. Therefore, this qualifications test effort was concentrated on critical areas specific to the microseismometer probe which is intended to be included in the Mars microprobe programs. Parameters that were evaluated included performance dependence on: illuminating angles, terrestrial temperatures, lifetime, as well as impact landing conditions. Our qualification efforts were limited to these most critical areas of concern. Most of the tested solar cell modules have met the requirements of the program except the impact tests. Surprisingly, one of the two single PIN 2 x 1 amorphous solar cell modules continued to function even after the 80000G impact tests. The output power parameters, Pout, FF, Isc and Voc, of the single PIN amorphous solar cell module were found to be 3.14 mW, 0.40, 9.98 mA and 0.78 V, respectively. These parameters are good enough to consider the solar module as a possible power source for the microprobe seismometer. Some recommendations were made to improve the usefulness of the amorphous silicon solar cell modules in space terrestrial applications, based on the results obtained from the intensive short term lab test effort.

Kim, Q.; Lawton, R. A.; Manion, S. J.; Okuno, J. O.; Ruiz, R. P.; Vu, D. T.; Vu, D. T.; Kayali, S. A.; Jeffrey, F. R.

2004-01-01

452

Heat transparent high intensity high efficiency solar cell  

NASA Technical Reports Server (NTRS)

An improved solar cell design is described. A surface of each solar cell has a plurality of grooves. Each groove has a vertical face and a slanted face that is covered by a reflecting metal. Light rays are reflected from the slanted face through the vertical face where they traverse a photovoltaic junction. As the light rays travel to the slanted face of an adjacent groove, they again traverse the junction. The underside of the reflecting coating directs the light rays toward the opposite surface of solar cell as they traverse the junction again. When the light rays travel through the solar cell and reach the saw toothed grooves on the under side, the process of reflection and repeatedly traversing the junction again takes place. The light rays ultimately emerge from the solar cell. These solar cells are particularly useful at very high levels of insolation because the infrared or heat radiation passes through the cells without being appreciably absorbed to heat the cell.

Evans, J. C., Jr. (inventor)

1982-01-01

453

Method for forming indium oxide/n-silicon heterojunction solar cells  

DOEpatents

A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

Feng, Tom (Morris Plains, NJ); Ghosh, Amal K. (New Providence, NJ)

1984-03-13

454

Low-cost epitaxial techniques for solar-cell fabrication  

NASA Astrophysics Data System (ADS)

The material characterization and epitaxial of solar cell structures on three grades of a candidate low cost upgraded metallurgical grade silicon substrate are discussed. Enough epitaxial solar cells to characterize the baseline performance of cells on these three substrate grades were fabricated and tested. With a 15 micrometer thick epitaxial structure grown on the purest form of UMG substrate, an average cell AM-1 efficiency of 12.5 percent was obtained. Similar structures grown on the less pure multicrystalline substrates grades result in efficiencies of 9 to 10.3 percent. A way of slicing these substrates which exposes larger grain areas and results in higher cell efficiencies is described. The application of slow cooling and gettering to the growth of thicker (greater than or equal to 50 micrometers) epitaxial solar cell structures was ineffective. The use of alternate silicon gas sources was explored by using silane for the growth of cell structures.

Daiello, R. V.; Robinson, P. H.

1980-04-01

455

Panel fabrication utilizing GaAs solar cells  

NASA Technical Reports Server (NTRS)

The development of the GaAs solar cells for space applications is described. The activities in the fabrication of GaAs solar panels are outlined. Panels were fabricated while introducing improved quality control, soldering laydown and testing procedures. These panels include LIPS II, San Marco Satellite, and a low concentration panel for Rockwells' evaluation. The panels and their present status are discussed.

Mardesich, N.

1984-01-01

456

Current- and lattice-matched tandem solar cell  

DOEpatents

A multijunction (cascade) tandem photovoltaic solar cell device is fabricated of a Ga/sub x/In/sub 1-x/P (0.505 equal to or less than x equal to or less than 0.515) top cell semiconductor lattice-matched to a GaAs bottom cell semiconductor at a low resistance heterojunction, preferably a p/sup +//n/sup +/ heterojunction between the cells. The top and bottom cells are both lattice-matched and current-matched for high efficiency solar radiation conversion to electrical energy.

Olson, J.M.

1985-10-21

457

Photochemically Generated Elemental Selenium Forms Conjugates with Serum Proteins that Are Preferentially Cytotoxic to Leukemia and Selected Solid Tumor Cells  

PubMed Central

The objective of this study was to determine if and how photoproducts contribute to the anti-tumor effect of merocyanine-mediated PDT. A panel of barbituric, thiobarbituric and selenobarbituric acid analogues of Merocyanine 540 was photobleached, and the resulting photoproducts were characterized by absorption, fluorescence emission, mass, energy dispersive X-ray, and X-ray photoelectron spectroscopy, and tested for cytotoxic activity against tumor cell lines and freshly explanted bone marrow cells. While all dyes were readily photobleached, only photoproducts of selone dyes showed cytotoxic activity. One-hour incubations with micromolar concentrations of selone-derived photoproducts were sufficient to reduce leukemia/lymphoma cells ?10,000 fold while preserving virtually all normal CD34-positive bone marrow cells. Of 6 multi-drug resistant tumor cell lines tested, 5 were as sensitive or more sensitive to photoproducts than the corresponding wild-type lines. Physicochemical characterizations of the cytotoxic activity indicated that it consisted of conjugates of subnano particles of elemental selenium and (lipo)proteins. The discovery of cytotoxic Se-protein conjugates provides a rare example of photoproducts contributing substantially to the anti-tumor effect of PDT and challenges the long-held view that Se in oxidation state zero is biologically inert. Agents modeled after our Se-protein conjugates may prove useful for the treatment of leukemia. PMID:22211823

Daziano, Jean-Pierre; Gnther, Wolfgang H.H.; Krieg, Marianne; Tsujino, Ichiro; Miyagi, Kiyoko; Anderson, Gregory S.; Sampson, Reyne W.; Ostrowski, Martin D.; Muir, Sarah A.; Bula, Raymond J.; Sieber, Fritz

2012-01-01

458

Advanced Silicon Solar Cell Device Physics and Design  

NASA Astrophysics Data System (ADS)

A fundamental challenge in the development and deployment of solar photovoltaic technology is a reduction in cost enabling direct competition with fossil-fuel-based energy sources. A key driver in this cost reduction is optimized device efficiency, because increased energy output leverages all photovoltaic system costs, from raw materials and module manufacturing to installation and maintenance. To continue progress toward higher conversion efficiencies, solar cells are being fabricated with increasingly complex designs, including engineered nanostructures, heterojunctions, and novel contacting and passivation schemes. Such advanced designs require a comprehensive and unified understanding of the optical and electrical device physics at the microscopic scale. This thesis focuses on a microscopic understanding of solar cell optoelectronic performance and its impact on cell optimization. We consider this in three solar cell platforms: thin-film crystalline silicon, amorphous/crystalline silicon heterojunctions, and thin-film cells with nanophotonic light trapping. The work described in this thesis represents a powerful design paradigm, based on a detailed physical understanding of the mechanisms governing solar cell performance. Furthermore, we demonstrate the importance of understanding not just the individual mechanisms, but also their interactions. Such an approach to device optimization is critical for the efficiency and competitiveness of future generations of solar cells.

Deceglie, Michael Gardner

459

Photon degradation effects in terrestrial solar cells  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

460

Solar Cells Active in Complete Darkness  

NASA Astrophysics Data System (ADS)

A graded bandgap multi-layer solar cell device structure was designed to absorb UV, visible and IR radiation, and to incorporate impact ionisation and impurity photovoltaic effects within one device. The design was experimentally tested with a well researched material system, MOVPE grown GaAs/AlGaAs. Open circuit voltages of ~1175 mV with highest possible FF values (0.83-0.87) and Jsc~12 mAcm-2 have been observed [1,3]. These parameters were independently verified by measuring in five different laboratories in Europe and United States including NREL. While the work is continuing to increase short circuit current density values, these devices were tested to explore the experimental evidence of impurity PV effect, as expected from this design. Responsivity measurements and PV activity in dark conditions have been carried out to investigate impurity PV effect in these devices. Responsivity measurements indicate current collection in the infra-red region confirming the contribution from IR photons. The I-V measurements in dark conditions produce open circuit voltages exceeding 750 mV confirming the contribution from surrounding heat radiation. The new features of graded bandgap devices enable impurity PV effect to dominate and create useful charge carriers, suppressing detrimental recombination process. These experimental results will be presented in this paper.

Dharmadasa, I. M.; Elsherif, O.; Tolan, G. J.

2011-03-01

461

Front and back polysilicon-contacted silicon solar cells  

NASA Technical Reports Server (NTRS)

The first use of a (silicon)/ (heavily doped polysilicon)/ (metal) structure to replace the conventional high-low junction (or back-surface-field, BSF) structure of silicon solar cells is reported. Compared with BSF and back-ohmic-contact control samples, the polysilicon-back solar cells show improvements in red spectral response and open-circuit voltage. Measurement reveals that a decrease in effective surface recombination velocity S is responsible for this improvement. Decreased S results for n-type (Si:As) polysilicon, consistent with past findings for bipolar transistors, and for p-type (Si:B) polysilicon, reported here for the first time. Though the present polysilicon-back solar cells are far from optimal, the results suggest a new class of designs for high efficiency silicon solar cells. Detailed technical reasons are advanced to support this view.

Lindholm, F. A.; Neugroschel, A.; Iles, P. A.; Arienzo, M.

1985-01-01

462

Window structure for passivating solar cells based on gallium arsenide  

SciTech Connect

Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

Barnett, A. M.

1985-10-01

463

Solar cell imaging and characterization by terahertz techniques  

NASA Astrophysics Data System (ADS)

Enhanced attention to solar cell development stimulates search of innovative solutions to their characterization and identification of possible technological defects in various steps of production in a contactless way. In the given work, investigat