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Ink Jet Printing for Silicon Photovoltaics: Cooperative Research and Development Final Report, CRADA Number CRD-04-00139

Description: The purpose of this CRADA was to combine the strengths of NREL and Evergreen Solar in the area of ink jet printing to develop a new manufacturing technology necessary to produce Si solar cells based on ribbon technology comparable to or exceeding current technologies.
Date: August 1, 2010
Creator: Ginley, D. S.
Partner: UNT Libraries Government Documents Department

Nanoparticle derived contacts for photovoltaic cells

Description: Contacts are becoming increasingly important as PV devices move to higher efficiency and lower cost. The authors present an approach to developing contacts using nanoparticle-based precursors. Both elemental, alloy and compound nanoparticles can be employed for contacts. Ink based approaches can be utilized at low temperatures and utilize direct write techniques such as ink jet and screen printing. The ability to control the composition of the nanoparticle allows improved control of the contact metallurgy and the potential for thermodynamically stable interfaces. A key requirement is the ability to control the interface between particles and between particles and the substrate. The authors illustrate some of these principals with recent results on Al, Cu and (Hg,Cu)Te. They show that for the elemental materials control of the surface can prevent oxide formation and act as glue to control the reactivity of the nanoparticles.
Date: October 20, 1999
Creator: Ginley, D.S.
Partner: UNT Libraries Government Documents Department

Fundamental studies of grain boundary passivation in polycrystalline silicon with application to improved photovoltaic devices. A final research report covering work completed from February-December 1979

Description: Several aspects of the electrical properties of silicon grain boundaries have been studied. The temperature dependence of the zero-bias conductance and capacitance of single boundaries has been measured and shown to be in good agreement with a simple double depletion layer/thermal emission (DDL/TE) model developed to predict the transport properties of such structures. In addition, it has been shown that deconvolution of the I-V properties of some boundaries via a deconvolution scheme suggested by Pike and Seager yields effective one-electron densities of trapping states which are in good agreement with estimates obtained by low temperature electron emission measurements. Experiments have also been performed which indicate that diffusion of atomic hydrogen into silicon grain boundaries greatly reduces this density of trapping states. In properly prepared, large grained polycrystalline samples all measurable traces of grain boundary potential barriers can be removed to substantial penetration depths after several hours exposure to a hydrogen plasma at elevated temperatures. Initial experiments on prototype polysilicon solar cells have shown that this passivation process can improve AM1 efficiencies. In order to more fully understand and develop this process for improving practical multigrained cells, several device research efforts with other DOE/SERI funded contractors have been initiated.
Date: February 1, 1980
Creator: Seager, C.H. & Ginley, D.S.
Partner: UNT Libraries Government Documents Department

Fundamental studies of grain boundary passivation in polycrystalline silicon with application to improved photovoltaic devices. A research report covering work completed from February 1981 to January 1982

Description: Grain boundary barrier heights and other properties were measured on a variety of Wacker poly-Si to test the contention of Redfield that as received samples had no potential barriers and that temperature anneals activate the impurities in the boundaries. Our results show that these generalizations are not true and that a variety of barrier behaviors are found. Several of our new analytical techniques for studying grain boundaries and their passivation have been upgraded, including a new cell for Fourier Transform Infrared (FTIR) studies, electrochemical techniques, and a laser scanning apparatus for imaging grain boundaries. Grain boundaries in a variety of samples have been successfully passivated by the use of both the Kaufman ion source and a dc discharge apparatus. 20% improvements in cell efficiencies have been observed in large grained poly-Si cells, and the time of treatment has been drastically reduced.
Date: September 1, 1982
Creator: Seager, C.H. & Ginley, D.S.
Partner: UNT Libraries Government Documents Department

Electrical and Morphological Properties of Inkjet Printed Pedot/PSS Films

Description: Organic solar cells and LEDs are becoming more popular because their low cost materials, potential manufacturability, and recent gains in efficiency make them feasible for widespread commercialization in the near future. One significant manufacturing problem, especially for OLEDs, is the cost associated with creating patterned devices with spatially non-specific deposition methods such as spincoating. Inkjet printing can remove this problem. In recent years, inkjet printed polyethylene(3,4-dioxythiophene)/ polystyrene sulfonate (PEDOT/PSS) has been incorporated into many organic devices to help charge transfer, but there has not been much research regarding the effect of different printing parameters on the electrical and morphological film properties. In this work, an atomic force microscope, four point probe, and Kelvin probe were used to study the effects of printing parameters on roughness, conductivity and workfunction. Inkjet printed PEDOT films were also compared to spincoated films to determine how the polymer deposition method affects the above properties. Generally, inkjet printing created rougher but more conductive films with a smaller workfunction. Additionally, it was demonstrated that the workfunction of PEDOT films could be tuned over a range of about 0.5 V by changing the solvent mixture or substrate surface pretreatment. All additives to the as received PEDOT/PSS suspension caused the workfunction to decrease. It was discovered that workfunction decreases as printing voltage increases, but the trend reverses after annealing the films. This phenomenon suggests that when DMSO interacts with PEDOT, the workfunction changes. Finally, the results support previous publications suggesting that DMSO increases conductivity through a screening effect and also by changing the distribution of PEDOT and PSS in the film.
Date: January 1, 2005
Creator: Garnett, E. & Ginley, D.
Partner: UNT Libraries Government Documents Department

Inks for Ink Jet Printed Contacts for High Performance Silicon Solar Cells: Cooperative Research and Development Final Report, CRADA No. CRD-06-199

Description: The work under the proposed CRADA will be a joint effort by BP Solar and NREL to develop new types of high performance inks for high quality contacts to silicon solar cells. NREL will develop inks that have electronic properties that will allow the formation of high quality ohmic contacts to n- and p-type crystalline silicon, and BP Solar will evaluate these contacts in test contact structures.
Date: January 1, 2013
Creator: Ginley, D.
Partner: UNT Libraries Government Documents Department

Ordered Nucleation Sites for the Growth of Zinc Oxide Nanofibers

Description: Organic photovoltaics (OPVs) offer a promising route to low cost photovoltaic (PV) technology that can be inexpensively manufactured on a large scale for use in power generation and commercial products. Solar power conversion efficiencies of laboratory scale OPV devices have recently reached ~5%; however, projected efficiencies of at least 10% will be required for commercialization. An analogous approach that has arisen recently that can potentially increase efficiencies employs metal oxide semiconductors as the electron acceptor, creating a hybrid organic-inorganic device. This approach offers the advantage that the conduction band of the oxide can be tuned in a systematic way through doping, thus potentially achieving higher photovoltages in the device. Additionally, nanostructures of these materials can be easily grown from precursor solutions, providing a technique to precisely control the nanoscale geometry. This work focuses on using ZnO, which is known to have high electron mobility (>100 cm2/Vs), as the electron acceptor. Nanofibers of ZnO can be grown from precursors such as zinc acetate or zinc nitrate to form arrays of nanofibers into which a conjugated polymer can be intercalated to form a composite PV device. The morphology of the nanofiber array is critical to the performance of the device, but current methods of nanofiber growth from a flat, polycrystalline nucleation layer allow for little morphological control. To overcome this limitation, we have created ordered arrays of ZnO nucleation sites with controllable size and spacing. Toluene solutions of diblock copolymer micelles with ZnCl2 incorporated into the micellar cores were spin-coated onto glass substrates and etched with an O2 plasma to yield hexagonally ordered arrays of ZnO nanoparticles that functioned as nucleation sites. Changing the concentration of ZnCl2 and the molecular weight and ratio of the diblock copolymer resulted in systematic variation in the size and spacing of the nucleation sites. Thermal anneal ...
Date: January 1, 2006
Creator: Wang, J.; Ginley, D.S. & Shaheen, S.
Partner: UNT Libraries Government Documents Department

Conducting and Optical Properties of Transparent Conducting Indium-Doped Zinc Oxide Thin Films by Sol-Gel Processing

Description: Transparent conducting oxides were successfully prepared from mixed zinc nitrate hexahydrate and indium nitrate hydrate solutions in ethylene glycol using sol-gel technique. The In content in the film was varied (0, 2, 10, 20, 40, 75 and 100 atom %). Films were prepared by spin coating of the liquid precursors followed by thermal decomposition at 400° C after each layer. According to X-ray diffraction (XRD) measurements, the pure ZnO and pure InO films (0 and at 100 % In) were crystalline as-deposited. The crystallinity was suppressed in mixed compositions such that the films with compositions between 10 and 75 at % were amorphous. All the films were transparent with the transmission cut-off frequency near 400 nm, which is characteristic of TCO materials. All as-deposited films were conductive with 0 and 100 atom % In having the lowest resistivities. The resistivity of all compositions were improved by post-deposition reducing anneal in pure Ar at 300° C. The lowest resistivity of 0.2 Ωcm was obtained for the pure ZnO after Ar anneal. It was two-orders of magnitude higher than reported in the literature for the In-doped ZnO, which was attributed to the low processing temperature. The resistivities of as-deposited and annealed in Ar films were increased by consequent air anneal at 300° C.
Date: January 1, 2004
Creator: Huang, S.; Kaydanova, T.; Miedaner, A. & Ginley, D.S.
Partner: UNT Libraries Government Documents Department

Metallization for Self Aligned Technology: Cooperative Research and Development Final Report, CRADA Number CRD-08-295

Description: In this CRADA NREL will modify/develop metallization inks that are compatible with 1366 Technologies technology. Various methods of deposition will be used to apply the inks to the textured silicon substrates. The goal of the project is to minimize the contact resistance while maximizing the cell efficiency.
Date: April 1, 2012
Creator: Ginley, D.
Partner: UNT Libraries Government Documents Department

Development of Inorganic Precursors for Manufacturing of Photovoltaic Devices: Cooperative Research and Development Final Report, CRADA Number CRD-08-308

Description: Both NREL and Rohm and Haas Electronic Materials are interested in the development of solution phase metal and semiconductive precursors for the manufacturing of photovoltaic devices. In particular, we intend to develop material sets for atmospheric deposition processes. The cooperation between these two parties will enable high value materials and processing solutions for the manufacturing of low cost, roll-to-roll photovoltaics.
Date: June 1, 2013
Creator: van Hest, M. & Ginley, D.
Partner: UNT Libraries Government Documents Department

Amorphous Indium-Zinc-Oxide Transparent Conductors for Thin Film PV: Preprint

Description: Amorphous InZnO's (a-IZO) basic PV applicability has now been demonstrated in prototype CIGS, Si Heterojunction (SiHJ) and organic photovoltaics (OPV). However, to move beyond initial demonstration devices, improved TCO properties and processibility of the a-IZO films are needed. Here, RF-superimposed DC sputtering was used to improve the reliable deposition of a-IZO with conductivity > 3000 S/cm.
Date: July 1, 2011
Creator: Perkins, J.; Gennett, T.; Galante, M.; Gillaspie, D. & Ginley, D.
Partner: UNT Libraries Government Documents Department

Particulate Contacts to Si and CdTe: Al, Ag, Hg-Cu-Te, and Sb-Te

Description: Our team has been investigating the use of particle-based contacts in both Si and CdTe solar cell technologies. First, in the area of contacts to Si, powders of Al and Ag prepared by an electroexplosion process have been characterized by transmission electron microscopy (TEM), TEM elemental determination X-ray spectroscopy (TEM-EDS), and TEM electron diffraction (TEM-ED). These Al and Ag particles were slurried and tested as contacts to p- and n-type silicon wafers, respectively. Linear current-voltage (I-V) was observed for Ag on n-type Si, indicative of an ohmic contact, whereas the Al on p-type Si sample was non-ideal. A wet-chemical surface treatment was performed on one Al sample and TEM-EDS indicated a substantial decrease in the O contaminant level. The treated Al on p-type Si films exhibited linear I-V after annealing. Second, in the area of contacts to CdTe, particles of Hg-Cu-Te and Sb-Te have been applied as contacts to CdTe/CdS/SnO2 heterostructures prepared by the standard NREL protocol. First, Hg-Cu-Te and Sb-Te were prepared by a metathesis reaction. After CdCl2 treatment and NP etch of the CdTe layer, particle contacts were applied. The Hg-Cu-Te contacted cells exhibited good electrical characteristics, with Voc > 810 mV and efficiencies > 11.5 % for most cells. Although Voc > 800 mV were observed for the Sb-Te contacted cells, efficiencies in these devices were limited to 9.1%, presumably by a large series resistance (>20 {Omega}) observed in all samples.
Date: October 22, 1998
Creator: Schulz, D. L.; Ribelin, D.; Curtis, C. J. & Ginley, D. S.
Partner: UNT Libraries Government Documents Department

Novel Materials for Photovoltaic Technologies: Preprint

Description: While existing photovoltaic technologies continue to advance, there are still many exciting opportunities in the area of novel materials. These opportunities arise because there is a substantial need for reducing the costs associated with the preparation and processing of photovoltaics, and because the theoretically possible photovoltaic efficiencies have yet to be achieved in practical devices. Thus it remains reasonable to continue photovoltaic research activity aimed at entirely new approaches to processing and at entirely new materials as the active media. This group identified three areas for further consideration: (a) Nano/molecular composites and hierarchical structures; (b) Organic semiconductors; and (c) Hot carrier devices.
Date: April 1, 1999
Creator: Alivisatos, P.; Carter, S.; Ginley, D.; Nozik, A.; Meyer, G. & Rosenthal, S.
Partner: UNT Libraries Government Documents Department

Superconducting active impedance converter

Description: This invention is comprised of a transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductor allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10--80 K temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology.
Date: December 31, 1992
Creator: Ginley, D.S.; Hietala, V.M. & Martens, J.S.
Partner: UNT Libraries Government Documents Department

Transparent Conducting Oxides: Status and Opportunities in Basic Research

Description: In this paper, we begin by discussing the historical background of transparent conducting oxides and then make some general remarks about their typical properties. This is followed by a short discussion of the desired properties for future applications (particularly photovoltaic devices). These are ambitious objectives but they provide targets for future basic research and development. Although it may be possible to obtain these properties in the laboratory, it is vital to ensure that account is taken of industrial perceptions to the development of the next generation of materials. Hence, we spend some time discussing industrial criteria. Next, we discuss key physical properties that determine the macroscopic physical properties that, in turn, affect the performance of devices. Finally, we select several key topics that ought to be included in future basic research programs.
Date: August 1, 1999
Creator: Coutts, T. J.; Perkins, J. D.; Ginley, D.S. & Mason, T. O.
Partner: UNT Libraries Government Documents Department

Irradiation-induced pinning in single-crystal and thin-film Tl sub 2 Ca sub 2 Ba sub 2 Cu sub 3 O sub 10 superconductors

Description: Magnetization relaxation measurements were used to directly measure the effects of ion irradiation on magnetic flux pinning. The pinning potential (U) in a Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub y} single crystal irradiated with 4.5 MeV protons, to a damage level of 4 {times} 10 {sup {minus}4} dpa, increased by {approx}25% at 25 K. In contrast, U for a highly oriented polycrystalline thin film irradiated with 300 keV He ions to a damage level of 2 {times} 10{sup {minus}4} dpa increased by only 5% at 25 K (and less at higher temperatures). Enhancement of the magnetization critical current density (J{sub cm}) is determined as a function of temperature and damage in the single crystal and thin film. High energy proton irradiation increased J{sub cm} in the single crystal by an order of magnitude at 25 K but had only a small effect on J{sub cm} in the thin film. 13 refs., 4 figs.
Date: January 1, 1990
Creator: Barbour, J.C.; Venturini, E.L. & Ginley, D.S.
Partner: UNT Libraries Government Documents Department

Rapid Thermal Annealing of HWCVD a-Si:H Films: The Effect of the Film Hydrogen Content on the Crystallization Kinetics, Surface Morphology, and Grain Growth

Description: We report the effect of the hydrogen (H) content (CH) on the crystallization kinetics, surface morphology and grain growth for Hot Wire CVD a-Si:H films containing 12.5 and 2.7 at.% H which are crystallized by rapid thermal anneal (RTA). For the high CH film we observe explosive H evolution, with a resultant destruction of the film for RTA temperatures >750 deg C. At RTA temperatures ~600 deg C, both films remain intact with similar morphologies. At this same lower RTA, the incubation and crystallization times decrease, and the grain size as measured by X-Ray Diffraction increases with decreasing film CH. SIMS measurements indicate that a similar film CH (<0.5 at.%) exists in both films when crystallization commences. The benefits of a two-step annealing process for the high CH film are documented.
Date: November 1, 2005
Creator: Mahan, A. H.; Reedy, R. C. Jr.; Ginley, D. S.; Roy, B. & Readey, D. W.
Partner: UNT Libraries Government Documents Department

Multi-Layer Inkjet Printed Contacts for Silicon Solar Cells: Preprint

Description: Ag, Cu, and Ni metallizations were inkjet printed with near vacuum deposition quality. The approach developed can be easily extended to other conductors such as Pt, Pd, Au, etc. Thick highly conducting lines of Ag and Cu demonstrating good adhesion to glass, Si, and printed circuit board (PCB) have been printed at 100-200 C in air and N2 respectively. Ag grids were inkjet-printed on Si solar cells and fired through the silicon nitride AR layer at 850 C, resulting in 8% cells. Next generation inks, including an ink that etches silicon nitride, have now been developed. Multi-layer inkjet printing of the etching ink followed by Ag ink produced contacts under milder conditions and gave solar cells with efficiencies as high as 12%.
Date: May 1, 2006
Creator: Curtis, C. J.; van hest, M.; Miedaner, A.; Kaydanova, T.; Smith, L. & Ginley, D. S.
Partner: UNT Libraries Government Documents Department

Multi-Layer Inkjet Printed Contacts to Si

Description: Ag, Cu, and Ni metallizations were inkjet printed with near vacuum deposition quality. The approach developed can be easily extended to other conductors such as Pt, Pd, Au, etc. Thick highly conducting lines of Ag and Cu demonstrating good adhesion to glass, Si, and printed circuit board (PCB) have been printed at 100-200 deg C in air and N2 respectively. Ag grids were inkjet-printed on Si solar cells and fired through the silicon nitride AR layer at 850 deg C, resulting in 8% cells. Next generation inks, including an ink that etches silicon nitride, have now been developed. Multi-layer inkjet printing of the etching ink followed by Ag ink produced contacts under milder conditions and gave solar cells with efficiencies as high as 12%.
Date: November 1, 2005
Creator: Curtis, C. J.; van Hest, M.; Miedaner, A.; Kaydanova, T.; Smith, L. & Ginley, D. S.
Partner: UNT Libraries Government Documents Department