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Monday Afternoon, October 20, 2008 Energy Science and Technology Focus Topic formation energy) and poor kinetics. In this presentation I will discuss our general methodology for tuning the hydrogen sorption thermodynamics of Room: 203 - Session EN+SE+NS+SS-MoA magnesium, through alloy design. We use a thin films approach to create a range of destabilized magnesium-based alloys and of accompanying Hydrogen Storage catalytic layers. Thin films make for ideal "model" systems that may be used for accurately and rapidly screening a variety of matrix and catalyst Moderator: J.F. Herbst, General Motors R&D Center, E. formulations. Because of the small diffusion distances, films also allow for Ronnebro, Sandia National Laboratories better separation of system thermodynamics from the kinetics. The synthesized films were tested volumetrically through multiple adsorption- 2:00pm EN+SE+NS+SS-MoA1 Hydrogen Storage for Automotive desorption cycles. The microstructures were characterized by neutron Vehicles: Methods and Materials, J.F. Herbst, General Motors R&D reflectometry and x-ray diffraction. We show that alloying magnesium with Center light elements that have weak hydrogen interaction, such as aluminum, is a very effective method for lowering the sorption temperature to near Fuel cells operating on hydrogen are a strong potential alternative to ambient. At certain compositions, the addition of aluminum promotes the internal combustion engines relying on fossil fuels for a variety of reasons. high-pressure γ-MgH2 phase at the expense of the equilibrium α-MgH2. At If a hydrogen fuel cell transportation future is to be realized, however, other compositions, the sorbed microstructure is a composite of α-MgH2 several major hurdles must be overcome, among them a light, compact, intermixed with α-AlH3. We also demonstrate that there is critical robust, and cost-effective system for storing hydrogen on a vehicle. High temperature above which the palladium catalyst caps are not stable, reacting pressure compressed gas is a viable option, but its implementation on the with the underlying material and losing their efficacy. Additionally, there commercial scale raises serious manufacturing and cost challenges. A will be a discussion of the processing and sorption kinetics of MgH2 - metal similar statement applies to cryogenic liquid storage, for which dormancy is catalyst - carbon nanotube (CNT) powder composites, and of direct TEM an additional issue. There is justifiable optimism that new materials may characterization of milled MgH2. offer significant improvement of the prospects for two other options: (1) hybrid approaches combining compressed gas and a high surface area physisorption medium at 77K, and (2) reversible storage near ambient 3:20pm EN+SE+NS+SS-MoA5 Thermodynamics and Kinetics of conditions. Progress on the broad materials front as well as recent research Hydrogen Storage in Metallic Nanoparticles Studied by Surface at GM R&D will be discussed. Plasmon Resonance Spectroscopy and Quartz Crystal Microbalance Techniques, C. Langhammer, I. Zoric, Chalmers University of Technology, Sweden, S.T. Kelly, B.M. Clemens, Stanford University, B. 2:20pm EN+SE+NS+SS-MoA2 Response of Ultra-Thin Palladium Kasemo, Chalmers University of Technology, Sweden Films to Hydrogen Exposure Studied by Low Energy Electron Microscopy and Diffraction, B. Santos, Universidad Autonoma de Nanosized metallic particles may have advantageous hydrogen storage Madrid, Spain, J.I. Cerda, J. de la Figuera, CSIC, Spain, K.F. McCarty, properties compared to the corresponding bulk material both in terms of Sandia National Laboratories, J.M. Puerta, CSIC, Spain sorption/desorption kinetics and in terms of storage capacity. In order to The ability of Palladium to store hydrogen is well known. Nevertheless understand the physical principles behind the influence of nanosizing on surface science studies of the exposure of Pd(111) samples to hydrogen hydrogen uptake/release properties, we have developed a novel localized have found only a dense hydrogen layer betwen the last palladium- surface plasmon resonance (LSPR) based optical hydrogen sensing scheme palladium layers, with additional hydrogen going into the bulk as a solid for nanoparticle storage systems. As model experiments we carried out solution.1,2 On Pd films a few atomic layers thick on a substrate which does measurements of the phase diagram and thermodynamic properties for not accept substantial quantites of hydrogen such as Ru, it should be supported Pd nanodisks, ranging in size from 30 nm to 300 nm. By possible to saturate completely the Pd film, and thus study the formation of monitoring the shift of the LSPR extinction peak upon hydrogen PdH hydride with surface science techniques. In particular, as there is a uptake/release as a function of hydrogen pressure, at different temperatures, substantial lattice mismatch betwen Pd and the beta-PdH hydride, the we have mapped out a series of pressure-concentration (p-C) isotherm for a incorporation of H in Pd-intersticial places should induce a significant range of particle sizes. These optical studies are complemented by expansion of the Pd layers. Although H itself is basically invisible to low gravimetric studies using a quartz crystal microbalance (QCM). In the latter energy electron diffraction, the change of the Pd-Pd distances should be case the corresponding p-C isotherms were obtained by monitoring the easily resolvable by LEED.3 In this work, we present a low energy electron frequency shifts when the Pd nanodisks were prepared on the QCM microscopy study of the hydrogren exposure of thin films of Pd on electrode and exposed to hydrogen environment at different temperatures. Ru(0001) and W(110). We characterize and study the growth and structure We have used Van't Hoff plots (log of the isotherm plateau pressure, in the of Pd thin films. LEEM is a useful technique to monitor and control the two-phase region, versus inverse plateau temperature), to obtain the growth of thin films in real space. Furthermore, a LEEM microscope can be enthalpy and entropy for hydride formation in Pd nanodisks of different used to acquire selected area diffraction (SAD-LEED) to determine the sizes. Furthermore, we have used Sievert's plots in the low hydrogen structure of such film.4 Our experiments reveals that Pd films 2 to 6 ML concentration limit (α-phase) to extract enthalpies and entropies of thick on Ru(0001) follow the fcc sequence with the Ru in-plane lattice hydrogen dissolution. An excellent agreement was obtained for the spacing, and present a corresponding expansion in the out-of-plane lattice corresponding thermodynamic variables obtained from LSPR sensing data spacing. Thicker films on Ru(0001) relax to a bulk-like Pd in-plane spacing. and QCM data. Similarities and differences to the corresponding Both thick films on Ru(0001) or W(110) show a slight expansion of the last thermodynamic variables for bulk systems are discussed. In addition, we interlayer spacing, in line with reported studies on the surface of bulk Pd. have carried out corresponding measurements with Mg nanoparticles We follow the dosing of atomic H on the Pd films by means of real-time "capped" with few nanometers of Pd to facilitate H2 dissociation. The LEED IV curves acquired by LEEM. We have found preliminary "capping" with a Pd layer circumvents the bottleneck associated with low indications that room and low temperature exposure produce a significant dissociative sticking of hydrogen on Mg. Double plateau isotherms were expansion in the interlayer distance for a 4 ML thick film. But this obtained indicating initial onset of the mixed phase formation at low expansion is smaller that the one expected for a full PdH beta-hydride hydrogen pressure in Mg nanoparticle followed by a corresponding two formation. phase onset in the Pd cap at higher pressure, characteristic for Pd 1 nanoparticles at a given temperature. In addition, we also present the QCM G.E. Gdowski, T.E. Felter and R.H. Stulen Surf. Sci. 181, L147, (1987) 2 and LSPR based studies of hydrogen uptake/release kinetics at different Sampyo Hong and Talat S. Rahman Phys. Rev. B 75, 155405 2007 3 T. E. Felter, Eric C. Sowa, and M. A. Van Hove, Phys. Rev. B 40 num. 2, 891-899, (1989) temperatures. 4 J. de la Figuera, et al, Surf. .Sci. 600, L105 (2006) 4:00pm EN+SE+NS+SS-MoA7 Atomistic Mechanisms of Reversible 2:40pm EN+SE+NS+SS-MoA3 Destabilized Magnesium-based Alloy Hydrogen Storage in Complex Metal Hydrides, P. Sutter, Brookhaven Thin Films as Model Systems for Hydrogen Storage, D. Mitlin, J. National Laboratory INVITED Haagsma, C. Ophus, C.T. Harrower, University of Alberta and NRC The storage of hydrogen in a lightweight, high-capacity medium with fast National Institute for Nanotechnology, Canada, M. Saoudi, H. Fritzsche, charge/discharge kinetics has been recognized as one of the primary National Research Council Canada, SIMS, Canadian Neutron Beam Centre, challenges in achieving the transition to a hydrogen-based economy. Chalk River Laboratories INVITED Hydrogen-rich compounds, such as complex metal hydrides, offer The key for achieving 100 °C - range hydrogen sorption is to have favorable potentially high storage capacities but the solid-state hydrogen storage thermodynamics, i.e. a hydrogen binding energy near 30 kJ/mol. Metallic reactions in these materials generally proceed slowly and in many instances magnesium possesses sufficient gravimetric and volumetric sorption are not reversible, i.e., re-hydrogenation of the depleted products cannot be capacity, but has unfavorable thermodynamics (-77 kJ/mol α-MgH2 realized by controlling temperature and hydrogen pressure alone. The use of 1 Monday Afternoon, October 20, 2008 doping to achieve reversibility and fast reaction kinetics has been result, studies exploring hydrogen interaction in storage materials are demonstrated successfully for a particular complex metal hydride, sodium important to facilitate further development of materials. Metal-organic alanate (NaAlH4). Here we discuss our recent efforts on identifying the Frameworks are promising candidates for hydrogen storage because their atomic-scale effects of such doping by microscopy and spectroscopy high surface area and porosity facilitate high hydrogen physisorption on experiments on well-defined model systems (e.g., single crystal surfaces), specific sites of the structures. This work explores the incorporation of closely linked to ab-initio theory and simulations. A comprehensive hydrogen into the structure using infrared (IR) absorption spectroscopy. IR understanding of important microscopic reaction mechanisms allows spectroscopy can distinguish possible H2 binding sites based on the deriving general guidelines for the use of dopants or catalysts to accelerate perturbation of the internal H2 stretch mode. The measurements are hydrogen storage reactions in alanates, and possibly in a broader class of performed at room temperature on three different types of MOF structures, solid-state storage materials. two of which have the general formula [M(bdc)(ted)0.5]-2DMF-0.2H2O, differing in the metal core M (Ni and Zn). These two compounds are 4:40pm EN+SE+NS+SS-MoA9 Microwave Irradiation for the isostructural and crystallize in the tetragonal phase (space group P4/ncc), Reversible Desorption of Hydrogen from Sodium Aluminum Hydride, they construct a 3D porous structures with relatively large pore size (~7-8Å, T.A. Dobbins, Louisiana Tech University and Grambling State University, pore volume (~0.63-0.84 cc/g) and BET surface area (~1500-1900 m2/g). R. Krishnan, Louisiana Tech University Another type of MOF is the [Ni3(HCOO)6]-DMF structure which crystallizes in space group P21/c and features a 1D open channels with Materials such as complex metal hydrides and hydrogen adsorbents have smaller pore diameters (~5-6 Å). Preliminary results show perturbation of been the primary focus of the on-board hydrogen storage research program. the H2 gas vibrational modes leading to a ~30 cm-1 shift of the ortho- and Complex metal hydrides offer great potential in making it into the para- peaks of the unperturbed H2. This perturbation is due to the interaction transportation industry due their reliable on-board reversibility. These of the hydrogen with the MOF and can be seen as evidence of the hydrogen materials can perform very well even after multiple dehydrogenation- adsorbed onto specific sites of the MOF. Although the data are taken for hydrogenation cycles. Conventional heating mechanisms have been used to high pressure H2 gas at room temperature, the shift is consistent with desorb hydrogen from complex metal hydrides. However, conventional previous observation of Bordiga et al.1 performed at very low pressures and heating processes involve high energy penalties (because the energy temperatures. The intensities of the perturbed ortho- and para- H2 peaks invested to heat the complex metal hydride is equal to or greater than the have a linear dependence with pressure, indicating that the perturbation of energy generated by a fuel cell using the desorbed hydrogen). This research the H2 with the MOF lattice is dominant, i.e. H2-H2 interactions are much is aimed at establishing the use of microwave irradiation to desorb hydrogen less important than in the pure H2 gas. from sodium aluminum hydride (NaAlH4). Microwave heating is known to 1 be more energy efficient than conventional heating. However, microwave S. Bordiga, J. G. Vitillo, G. Ricchiardi, et al., Interaction of hydrogen with MOF-5 Journal of Physical Chemistry B 109, 18237 (2005). fields are also known to drive order to disorder reactions in the hydrides, thus resulting in amorphous desorption products. This work reports a method to use microwave irradiation to desorb hydrogen from NaAlH4 via the reversible desorption pathway. This is the first report of using microwaves to drive a dehydrogenation reaction with the same pathway as driven by conventional heating processes. The method established in this research makes use of the energy efficiency of microwave irradiation and can be extended to other hydride systems for future research. Funding for this project was provided by the Department of Energy, Office of Basic Energy Sciences (Contract No.: DE-FG02-05ER46246). 5:00pm EN+SE+NS+SS-MoA10 Alane Formation on Al(100) and Ti- doped Al(100), I.S. Chopra, J.-F. Veyan, Y.J. Chabal, University of Texas at Dallas, S. Chaudhuri, Washington State University Complex metal hydrides, such as NaAlH4, are candidates for hydrogen storage as they can reversibly release and recapture hydrogen. Alane Clusters (AlxHy) are believed to be the mass transport intermediate in the hydrogen storage reactions involved in hydrogen uptake and release. Understanding the surface chemistry behind the formation and evolution of alane clusters is therefore important to lower the temperatures needed for these processes. Since doping metallic Al is critical for H2 dissociation, we have undertaken a comprehensive study of H interaction with Al(100) and Ti-doped Al(100) surfaces to better understand the atomic scale mechanisms underlying this reversible hydrogen storage behavior. The results have been compared with similar study performed earlier on the Al(111) and Ti doped Al(111) surface. In-situ infrared absorption spectroscopy had previously shown1 that the nature of alanes (size, bonding configuration) formed on Al(111) depends on both H exposure and sample temperature. At low temperatures (~90K), small alanes such as AlH3 and Al2H6 are predominant. At higher temperatures (~ 250K), larger alanes are formed. The study of alane formation on the Al(100) surface as a function of H exposures and substrate temperatures make it possible to explore the dependence of the alane formation on the crystal orientation. The effect of Ti doping is also explored as a function of both Ti concentration and H2 pressures. Our first-principles calculations indicate that Ti atoms should occupy hollow sites of the (100) unit cell. We are therefore using LEED to test whether this site is indeed the most favorable and IR spectroscopy to explore whether Ti in that site does dissociate H2. On Al(111), no dissociation was observed for H2 pressure up to 10-6 Torr. We are therefore exploring dissociation up to 10-4 Torr on Al(100). Finally, we are using TPD to probe the nature of desorbed species from both Al(100) and Ti – doped Al(100) surfaces. 1 Santanu Chaudhuri, Sylvie Rangan, Jean-Francois Veyan, James T. Muckerman,Yves J. Chabal, J.Am. Chem. Soc. (submitted). 5:20pm EN+SE+NS+SS-MoA11 Infrared Spectroscopy Studies of Hydrogen Interaction in Metal Organic Frameworks, N. Nijem, J.-F. Veyan, University of Texas at Dallas, J. Li, Rutgers University, Y.J. Chabal, University of Texas at Dallas Hydrogen storage is one of the most challenging problems in hydrogen- based energy technology. One of the goals of hydrogen storage is the ability to store a high volumetric density of hydrogen at room temperature. As a Monday Afternoon, October 20, 2008 2 Tuesday Morning, October 21, 2008 Energy Science and Technology Focus Topic process at the turning point of the transition mode and metallic mode and without incorporation in the films. The photocatalytic results showed that Room: 203 - Session EN+BI+SS+SE-TuM there was an optimal non-stoichiometry of titania films in terms of methane yield from CO2 reduction. Under UV illumination, the best CO2 conversion Catalysis for Energy Sustainability percentage was around 22%. In addition, both from reaction tests under visible light and the optical measurements, we determined that non- Moderator: D.E. Ramaker, George Washington University stoichiometric mixed phase titania films showed a strong light absorption shift into the visible range compared to commercial standard Degussa P25, 8:00am EN+BI+SS+SE-TuM1 Size, Shape, and Support Effects in which has a similar phase composition. SEM and TEM results showed film Oxidative Coupling Reactions, C.L. Marshall, W. Setthapun, S. Mucherie, morphology with a high density of solid-solid interfaces developed in the Argonne National Laboratory, H.S. Kim, Northwestern University, J.A. films. Both EELS and XPS results identified the Ti3+ species in addition to Libera, J.W. Elam, Argonne National Laboratory, P.C. Stair, Northwestern Ti4+. Most of the Ti3+ species were located at the interfaces of titania University INVITED columns, where they might serve as the reactive interfacial sites for visible In this paper we describe the characterization and catalytic performances in light harvesting or electron trapping. the reaction of ODH of propane over new nanostructured membrane 1 L. Chen, et al., Photoreduction of CO2 by TiO2 Nanocomposties Synthesized through Reactive DC catalysts composed of vanadium species supported on different metal Magnetron Sputter Deposition. Thin Solid Films, 2008. in review. 2 oxides (Al2O3, Nb2O5, TiO2), which have been fabricated using the L. Chen, et al., Fabricating Highly Active Mixed Phase TiO2 Photocatalysts by Reactive DC Magnetron Sputter Deposition. Thin Solid Films, 2006. 515(3): p. 1176-1181. combination of anodic aluminum oxide (AAO) and atomic layer deposition 3 Hurum, D.C., et al., Probing reaction mechanisms in mixed phase TiO2 by EPR. Journal of Electron (ALD).1 The aim of this study is to determine the role played by the Spectroscopy and Related Phenomena, 2006. 150: p. 155-163. nanostructured materials and the nature of the support oxide on the reactivity of these AAO membrane catalysts in terms of activity and 9:40am EN+BI+SS+SE-TuM6 Variations in Metal-Ligand Effects on selectivity to propylene. Pt in PtnM (M = Ru,Mo,Sn) Electrocatalysts as Exhibited by in situ XANES and EXAFS Measurements in Methanol, D.E. Ramaker, F.J. 8:40am EN+BI+SS+SE-TuM3 Application of Single-Wall Carbon Scott, George Washington University, S. Mukerjee, Northeastern University Nanohorns, M. Yudasaka, Advanced Industrial Science and Technology Metal-ligand effects on Pt are commonly utilized to decrease the CO (AIST), Japan INVITED poisoning of the anode in methanol as well as to increase the activity for The discovery of spherical aggregates of single-wall carbon nanohorns oxygen reduction at the cathode. However, these effects are not clearly (SWNHs) was reported in 1999. The aggregates were called dahlia-like, understood because of the general lack of information on the particle bud-like, and seed-like SWNHs based on their forms. Since the dahlia-type morphology (M island size, homogeneity, etc.) and CO or OH adsorbate aggregate (D-NHag) was obtained with the highest purity (about 90%) coverages. In this work, in situ X-Ray Absorption Spectroscopy (XAS) among the three types, SWNH applications have been studied mainly using measurements, in the near edge and extended regions (XANES and the D-NHag. The individual SWNH has a structure similar to SWNTs, EXAFS) at the Pt L3 edge, were carried out on three different carbon- namely, a tube-like structure made of a graphene sheet, but with larger supported electrocatalysts (Pt3Mo, Pt4Mo, and PtSn) in an electrochemical diameters (2-5 nm), shorter length (40-50 nm), and horn-shaped tips with a cell in 1 M HClO4 along with 0.3 M methanol. The CO, OH, O, and Hupd cone angle of about 19o. Studies of various applications of D-NHag relative adsorbate coverages on Pt are determined as a function of the revealed that they are a unique medium for adsorption, support, and storage applied potential via the ΔXANES technique and compared with of materials. This uniqueness mainly comes from mountain-valley structure comparable data reported for three different PtRu electrocatalysts (PtRu of the D-NHag surfaces and wide inner-hollow spaces. The mountain-valley Etek, PtRu Watanabe, and Pt3Ru) reported previously1. The average particle surface morphology was suitable for supporting material clusters with small morphology of each catalysts is determined from EXAFS coordination sizes. The reason for this may be because migration on the SWNHag numbers and a modeling technique.1 The onset of the n-fold O atom surface was suppressed, so coalescence of the clusters was avoided. In fact, coverage between 0.5 and 0.9 V (RHE) tracks essentially with the particle the sizes of Pt-particles supported on D-NHag were small, about 1 nm. size. The more reactive Sn and Mo atoms interact more strongly with Pt, When the Pt/SWNHag was used as fuel-cell electrodes, the battery and hence the ligand effect for the M and MOn islands are comparable, in characteristics were significantly improved. The inside spaces of SWNHs contrast to that for Ru vs. RuOn. Our results are correlated with the were made accessible by making holes at the tips and defects of sidewalls. extensive electrochemical results found in the literature on similar PtnM It was easy to incorporate various materials (C60, metals, inorganic and catalysts. The results suggest that the strength of the ligand effect increases organic molecules including drugs, etc.) inside SWNHs in the liquid-phase in the order Ru < Mo, MoOn < Sn, SnOn ≤ RuOn, where the relative Pt-CO at room temperature, where the incorporating quantities were controllable. bond strength is found to decrease and the Pt-OH bond strength increases The materials were moderately bound inside SWNHs, which enabled the with ligand effect. In the Sn and Mo bimetallics, the ligand effect is found rate-controlled release of the incorporated materials. It was also easy to to be sufficiently strong to allow CO replacement by H2 at low currents. individually disperse D-NHag in various solvents. They were well dispersed 1 F. J. Scott, S. Mukerjee, and D. E. Ramaker, J. Electrochem. Soc. 154, A396-A406 (2007). even in aqueous solutions, which will make possible biological applications of D-NHag. We previously reported that dexamethasone, a drug, was 10:40am EN+BI+SS+SE-TuM9 Controlling the Activity of Fuel Cell loaded in/on SWNHs in aqueous solutions and released in cell culture medium, exhibiting its drug effect in several ways. SWNH is quasi-SWNT, Electrode Materials by Tuning the Surface Electronic Structure, J.K. Norskov, Technical University of Denmark INVITED but, its usefulness is different from that of SWNT. We believe that D-NHag will be suitable for a catalyst support and material-delivery medium. The performance of low temperature fuel cells based on proton conducting Acknowledgement: I am grateful to all the collaborators, especially membranes is severely hampered by an overpotential at the cathode where Professor Iijima, and JST for supporting this research through ICORP and molecular oxygen combines with protons and electrons to form water. To SORST schemes. understand the origin of this problem a method has been developed that 1 allows a theoretical treatment of chemical reactions at the water-solid S. Iijima, et al., Chem. Phys. Lett. 309 (1999) 165. interface in the presence of an electrical bias on the basis of electronic structure calculations. Extensive density functional calculations have 9:20am EN+BI+SS+SE-TuM5 Reducing Carbon Dioxide to Methane allowed an identification of the origin of the overpotential for the under Visible Light Illumination by Non-stoichiometric Mixed Phase commonly used electrode material, platinum, as well as insight into the way Titania Thin Films, L. Chen, M.E. Graham, P.A. DeSario, K.A. Gray, alloying can change the surface electronic structure of platinum to reduce Northwestern University the overpotential. The reverse reaction, electrochemical water splitting, is Non-stoichiometric mixed phased titania composites were deposited by also discussed, and it is shown that the performance of different classes of reactive DC magnetron sputtering. Previously we1-3 demonstrated that there inorganic materials as electrocatalyst as well as the catalytic center for are solid-solid interfaces with highly reactive interfacial sites created within biological water splitting in photosystem II can be understood within the mixed phase titania thin films, and we observed by EPR measurement that same conceptual framework. the bulk composition of the films was not fully stoichiometric. The objective of this study is to explore the role of non-stoichiometry in mixed 11:20am EN+BI+SS+SE-TuM11 Resolving the Electronic Properties phase titania in terms of photoresponse and photocatalytic performance in of Catalytically Important Pd/Au Alloys at the Sub-Nanometer Level, reducing CO2 to methane. The control of oxygen partial pressure during A.E. Baber, H.L. Tierney, E.C.H. Sykes, Tufts University film deposition yielded different levels of non-stoichiometry in films Palladium/gold (Pd/Au) bimetallic alloys have been used to catalyze deposited mostly in the transition mode. Trace amounts of nitrogen were important processes such as the synthesis of vinyl acetate and hydrogen introduced during the sputtering process to stabilize the reactive sputtering peroxide as well as some oxidative reactions (methanol, formic acid, CO). 3 Tuesday Morning, October 21, 2008 Low temperature, ultra-high vacuum scanning tunneling microscopy (LT- UHV STM) is used not only to image bimetallic alloys, but also to spectroscopically probe the local electronic changes in both Pd and Au atoms when the two are alloyed. We have used STM to evaluate the surface composition of a real bimetallic alloy system and have found that the unique herringbone reconstruction of Au{111} provides entry sites for the incorporation of Pd atoms. We were able to differentiate between surface, subsurface and overlayer Pd atoms and study the temperature dependence of the preferred Pd destination. As the deposition temperature increases, the location of Pd changes from mostly overlayer to surface to subsurface. Scanning tunneling spectroscopy was used to examine the local density of states (LDOS) of individual Pd and Au atoms in both surface and subsurface sites in order to investigate the changes in the LDOS of a reactive metal alloyed in a more noble metal. It was found that in both surface and subsurface sites, Pd atoms displayed a LDOS very similar to the surrounding gold atoms, except for a small region at the band edge of the Au surface state in which the electron density was depleted. Pd atoms act as scattering sites for the surface electrons but do not fully quench the surface state. This is the first example of a simultaneous atomic-scale geometric and electronic characterization of a real PdAu catalytic system. 11:40am EN+BI+SS+SE-TuM12 Water-Gas-Shift Reaction on Metal- Oxide Catalysts, P. Liu, S. Ma, J.A. Rodriguez, J. Hrbek, Brookhaven National Laboratory The water-gas shift (WGS) reaction (CO + H2O → H2 + CO2) is a critical process in providing pure hydrogen for fuel cells and other applications. However, current industrial catalysts (Fe-Cr or Zn-Al-Cu oxides) are pyrophoric and require complex activation steps before usage. A fascinating puzzle has recently emerged: Au/CeO2 and Au/TiO2 nanomaterials show high activity for WGS catalysis. This is remarkable since in bulk form Au, ceria and titania are not known as WGS catalysts. The nature of the active phase(s) in these metal-oxide nanocatalysts is unclear at the present time, which impedes the design and optimization of WGS catalysts. We have carried out coordinated experimental and theoretical studies to address this problem. The experiments show that the model catalysts, Au/CeO2(111) or TiO2(110) and inverse CeO2 or TiO2/Au(111), display activities comparable to good WGS catalysts ( i.e., Cu(100) and Cu(111)). Theoretical calculations based on density functional theory (DFT) are also carried out to understand the active sites in the oxide-gold catalysts, by probing reaction scenarios on Au, titania, and Au-TiO2 (Au/TiO2 and TiO2/Au(111)) catalyst model structure. In accordance with experiments, our calculations show a very high barrier for the dissociation of water on Au and the formation of very stable formate species on titania that prevents the production of H2 and CO2. The model Au-TiO2 catalyst overcomes these bottlenecks: the moderate chemical activity of gold is coupled to the more reactive oxide. The dissociation of water takes place on the oxide easily, a reaction that extended surfaces and nanoparticles of Au cannot perform. CO adsorbs on gold sites located nearby (bifunctional catalyst). Then all the subsequent steps occur at the oxide-metal interface at a reasonable speed. Our results imply that the high activities of Au/CeO2 and Au/TiO2 nanocatalysts in the WGS reaction depend heavily on the direct participation of oxide-metal interface. The diversity of nanoparticle structures and the interplay with the support highlight the importance of identifying critical structural motifs to model catalyst function. This research was carried out at Brookhaven National Laboratory and supported by the US Department of Energy (Chemical Sciences Division, DE-AC02-98CH10886). Tuesday Morning, October 21, 2008 4 Tuesday Afternoon, October 21, 2008 Energy Science and Technology Focus Topic 2:40pm EN+EM+NS+PS-TuA4 Nanoscale Heterojunction Engineering Room: 203 - Session EN+EM+NS+PS-TuA to Grow High-Quality Ge on Si for Multijunction Solar Cells, D. Leonhardt, J. Sheng, T.E. Vandervelde, University of New Mexico, J.G. Photovoltaics Cederberg, M.S. Carroll, Sandia National Laboratories, S.M. Han, University of New Mexico Moderator: B.J. Stanbery, Helio Volt Corporation, J. Xue, In an effort to reduce the manufacturing cost of multijunction solar cells, we University of Florida have scaled up a process to grow low-defect-density Ge films on 2-inch- diameter Si substrates. This growth technique makes use of nanoscale 1:40pm EN+EM+NS+PS-TuA1 Thin films, Plasmas and Solar Cells, heterojunction engineering to minimize the interfacial strain density. The M.C.M. van de Sanden, Eindhoven University of Technology, The engineered substrates may potentially replace the Ge wafers that are Netherlands INVITED currently used in multijunction solar cell fabrication, if the Ge film's bulk Solar cells, devices which can convert sunlight directly into electricity by and surface quality can match that of the epi-ready Ge wafers. We will the photovoltaic (PV) effect, is now recognized as one of the options to present results for the scaled-up process of Ge film production, including provide a significant fraction of the energy mix in 2050 to power the world. key aspects of the nucleation process and film characterization, using Presently the PV industry is booming and two important challenges lie transmission electron microscopy and etch pit counting. Next, we present ahead: increasing the efficiency of conversion of sunlight into electricity our efforts to produce a high-quality surface finish, using chemical- and obtaining the required scale in terms of the surface area produced. The mechanical planarization, and method for cleaning and passivating the Ge latter requires high throughput processing of solar cells in all its aspects. surface. Additionally, results of GaAs film growth on our engineered Increasing the efficiency is scientifically attaining the most attention, but substrates will be presented and compared to growth on Ge and GaAs history has shown that more cost reduction can be obtained by improving wafers, both offcut and nominal. We find that the offcut wafers effectively processes and increasing the scale of the industry. This talk will address eliminate anti-phase domains in the GaAs. We also observe room- both challenges by discussing the role of thin film and plasma technology. temperature photoluminescence from GaAs epilayers grown on our Presently the solar cell market is dominated by solar cells based on engineered Ge/Si substrates. Lastly, future work and directions will be crystalline silicon. In this solar cell technology, where the photo-active discussed in light of our findings. material is wafer based silicon, thin films still play an important role to increase efficiency by effectively passivating bulk and surface defects and 3:00pm EN+EM+NS+PS-TuA5 On a New Concept of Tandem enhancing light trapping in the solar cell. The high rate deposition of a- Photovoltaic Cells Based on III-V Semiconductor Materials, M. SiNx:H as passivation and anti-reflection coating, by means of the Emziane, Masdar Institute of Science and Technology, UAE, R.J. Nicholas, expanding thermal plasma technique, will be shortly reviewed. Possible University of Oxford, UK combinations with novel concepts to convert the solar spectrum will be We have investigated single-junction and double-junction photovoltaic addressed. Recently, we also introduced plasma assisted atomic layer devices using ternary and quaternary InGaAs(P) semiconductor materials. deposition of Al2O3, a high k dielectric containing a large amount of These were designed and optimized for potential applications in negative charge, to passivate future p-type emitters on n-type silicon based conventional photovoltaics, thermophotovoltaics and concentrator solar cells. Demonstration of improved performance of n-type solar cells photovoltaics.Different bandgaps were considered for single-junctions, and using this type of passivation layer with an efficiency as high 23.2 % will be various bandgap combinations were simulated for the top and bottom cells discussed. To obtain the required large scale by 2050 further improvement of the tandem devices where the structure comprises two single-junction of thin film solar cell technology will be essential, both in terms of cells connected back to back and separated by a middle common contact. materials as well as in terms of processes. Apart from the need for high For both single and double-junctions, the device structures were modeled throughput deposition of the photo-active materials, additional thin film and optimized as a function of the doping concentration and thickness of the technologies will be needed for barrier layers on substrates to limit impurity active layers, and the simulations show that optimum device performance transport, for efficient light trapping (textured surfaces and anti-reflection can be achieved by using relatively thin structures and low doping layers) and last but not least encapsulation layers to guarantee the lifetime concentrations in the emitter and base layers. The variation of the device of the thin film solar cell. Apart from the further development of improved performance with the black-body source temperature, incident intensity and materials and device concepts, process monitoring and control to improve operating temperature was also simulated and discussed. Due to the split of quality and throughput becomes more and more important. I will discuss the incident spectrum, the bottom cell response is found to be different from here the monitoring of high rate deposition of microcrystalline silicon by that expected for a single-junction cell having the same bandgap. The means of optical emission spectroscopy. This optical probing method also optimal bandgap combination that delivers the best total efficiency for the enables the in situ detection of the crystallinity of the material deposited as tandem device was also determined and the data discussed. well as fundamental insights in the growth mechanism. 4:00pm EN+EM+NS+PS-TuA8 Thin Film Preparation of 2:20pm EN+EM+NS+PS-TuA3 Effects of Nanostructures formed by Chalcopyrites for Solar Cells and Fundamental Material Physics, S. Plasma Etching on Reflectance of Solar Cells, S.H. Ryu, C. Yang, W.J. Siebentritt, University of Luxembourg INVITED Yoo, Sungkyunkwan University, Korea, D.-H. Kim, T. Kim, Samsung Thin film solar modules are expected to be the next generation of Advanced Institute of Technology, Korea photovoltaics technologies. Their cost reduction potential has been We investigated the lithography-free plasma etching methods to modify estimated much higher than that of Si wafer technologies. Among the surface of single crystalline Si which was widely used for manufacturing of various thin film technologies solar cells based on chalcopyrite (CuInGaSe2, solar cells. Experiments were performed using SF6/O2 gases dry etching for CIGS) absorbers show the highest efficiencies, reaching 19.9% in the lab. the purpose of reducing the reflectivity at the Si surface. Upon inductively These record solar cells are prepared by a high vacuum co-evaporation coupled plasma etching in SF6/O2 pillar-shaped nanostructures were process that proceeds in three stages with different composition. A formed on the surface which changed to black in color. The absorption simplified two stage co-evaporation process is used in the first mass factor was estimated by measuring reflection and transmission on the production of chalcopyrite solar modules. Further industrial processes are surface across near UV to near IR. Before etching, reflectance of Si wafer the sputter deposition of metallic precursors which are reacted in an was ~ 35% in the wavelength range of 600-1000 nm and > 50% in the annealing process to the semiconductor compound. Recently wavelength range of 200-400nm, whereas it decreased to < 5% after electrochemical deposition has appeared as a low cost approach to the performing SF6/O2 plasma etching. The absorption factor of Si wafer after precursor deposition. In all cases the knowledge on fundamental growth etching was increased up to ~ 90% from 65% compared to that without processes, nucleation behaviour and detailed reaction is limited. The details etching, in the wavelength range of 600-1000 nm. Furthermore, various of the processes and their advantages and disadvantages for solar module etching methods and conditions to suppress reflectivity in a broad spectral production will be discussed. The afore mentioned deposition processes range were investigated for optimization of the surface property of the solar result in polycrystalline films with grain sizes of approximately 1 cells, ie, enhancement of solar cell efficiency. We investigated the effects of micrometer. For the investigation of the fundamental material physics it is various processing parameters on surface property by changing gas ratio, necessary to obtain grain boundary free material. The lattice mismatch bias power and etching time. The current-voltage characteristics on the between CuInSe2 and CuGaSe2 on one side and GaAs on the other side is surface textured solar cells showed that short circuit current (Isc) and open between 2.2 and -0.7% and allows epitaxy of chalcopyrite films on GaAs. circuit voltage (Voc) changed sensitively depending on the surface Several methods for the epitaxy have been developed: metal organic vapour treatment. The relation between the surface morphology and the absorption phase epitaxy (MOVPE), molecular beam epitaxy (MBE) and a hybrid factor was analyzed. 5 Tuesday Afternoon, October 21, 2008 sputter/evaporation process. The specifics of these processes will be briefly discussed and some results of epitaxial films will be presented. 4:40pm EN+EM+NS+PS-TuA10 Influence of a Single Grain Boundary on Epitaxial CuInSe2 Film Growth, A.J. Hall, D. Hebert, A. Rockett, University of Illinois at Urbana-Champaign Very large multigrain copper indium diselenide (CuInSe2) films were grown on gallium arsenide (GaAs) multigrain wafers using a hybrid sputtering/effusion growth process. Scanning electrom microscopy (SEM) morphology shows excellent epitaxial grain growth on the substrate with intimate grain boundary contact. Electron backscatter diffraction analysis shows a crystal misorientation common axis and misorientation angle for a high-angle, non-twin, boundary. Atomic force microscope and transmission electron microscope images are presented which confirm the surface morphology and the atomic intimacy of the grain interface. Kelvin probe force microscopy shows that the grain-boundary has little electrical influence on the film in comparison to other features present in the crystallites. Growth of large multicrystalline or bicrystalline CuInSe2 films allows more careful study of both physical and electrical influence of grain- boundaries on film properties. Current work on the physical influence of a single boundary on film growth is discussed. Tuesday Afternoon, October 21, 2008 6 Tuesday Afternoon Poster Sessions Energy Science and Technology Focus Topic ZnO(11-20) single crystal surfaces, we have compared the position of the HOMO and LUMO levels of the N3 Ruthenium based-dye, of isonicotinic Room: Hall D - Session EN-TuP acid and catechol molecules. Isonicotinic acid, as a simpler form of the linker that binds the N3-dye on TiO2, is found to have a very similar Energy Focus Topic Poster Session electronic structure as the N3-dye in the unoccupied states. This is consistent with the electronic transfer scheme where N3 excitation occurs from the HOMO localized on its Ruthenium center, to the LUMO EN-TuP1 Resistive Oxygen Gas Sensor Using Pure and Doped CeO2, delocalized on the dye linker to the surface. Catechol on TiO2(110) however S. Gupta, Portland State University, S.V.N.T. Kuchibhata, M.H. Engelhard, has no electronic states degenerated with the bottom of the conduction band P. Nachimuthu, V. Shutthanandan, L.V. Saraf, S. Thevuthasan, Pacific edge. As a consequence the lower energy excitation process occurs via a Northwest National Laboratory, S. Prasad, Portland State University HOMO to conduction band process. We have also measured the electronic Oxygen sensors have come into wide use in automotive and industrial structure of N3 adsorbed on more technologically relevant TiO2 anatase applications as leak detectors, industrial process flow evaluators, as well as nanoparticle and ZnO nanorod substrates. in life science industry in diagnostic applications such as respiratory vital signs monitoring, and metabolic rate monitoring. All these applications EN-TuP4 High Efficiency Down Converting Powder Phosphors for require the fast monitoring of the oxygen gas. Hence we have explored the Solid Sate Lighting Applications, S. Maslov, D. Bera, L. Qian, P.H. possibilities to develop an oxygen sensor operating on the chemiresistive Holloway, University of Florida principle at aggressive environments with a reduced response time. Ceria is known for its unique ability to lose or gain oxygen based on the ambient High performance blue and white organic light emitting diodes (OLED) environment. The doping of trivalent elements including Y, Sm and Gd in offer improved efficiencies for solid state lighting. A down converting ceria is expected to create oxygen vacancies and eventually influence phosphor layer allows color tuning capabilities when coupled with a blue virtually all types of transport properties like ionic and electronic properties. emitting OLED, and leads to improved efficacies approaching 80 lm/watt. The overarching objective of this project is to study the effects of changes The efficacy, CIE color coordinates, color rendering index, and angle in surrounding conditions such as temperature, pressure, dopant resolved photoluminescence intensity were characterized versus film concentration on the transport properties of doped ceria films. High quality, thickness and phosphor weight fraction. Due to scattering by phosphor epitaxial, pure and doped ceria thin films were grown on sapphire (0001) particles, the initially forward focused light is converted to a Lambertian substrates using oxygen plasma assisted molecular beam epitaxy (OPA- distribution of intensity. The method for applying powder thin films will be MBE) and characterized them using several bulk and surface sensitive illustrated and discussed. The advantages and disadvantages of PMMA techniques. Conductivity in these films was measured as a function of versus silicones for the dispersion matrix will be reported. Optimum temperature (room temperature to 700C) under various oxygen partial phosphor layers were those with high quantum yield and maximum light out pressure (1 torr to 100 torr) and vacuum conditions. Preliminary results coupling. show that response of the doped ceria film is much faster than the pure ceria films under the same conditions of temperature and pressure. Moreover EN-TuP5 Ionic Conductivity of Scandia Doped Zirconia Thin Films by response time of these films is few milliseconds with the change in the Oxygen-Plasma-Assisted Molecular Beam Epitaxy, M.H. Engelhard, oxygen partial pressure. It was observed that the samarium concentration of Pacific Northwest National Laboratory, Z.Q. Yu, Nanjing Normal approximately 4-6 atom% is the optimum doping content. University, China, S.V.N.T. Kuchibhatla, C.M. Wang, O. Marina, W. Jiang, V. Shutthanandan, P. Nachimuthu, R. Devanathan, L.V. Saraf, S. EN-TuP2 A Closer Look at H-CO Interaction on the Platinum Thevuthasan, Pacific Northwest National Laboratory Surface, T. Roman, H. Nakanishi, H. Kasai, Osaka University, Japan The development of electrolyte materials with high oxygen ion conductance The system comprised of coadsorbed hydrogen and carbon monoxide on at relatively low temperatures is essential to increase the efficiency and platinum has been the subject of a number of experimental work due to its lifetime of electrochemical devices, such as solid oxide fuel cells (SOFC). high relevance in heterogeneous catalysis, particularly in relation with Recently, there has been considerable interest in scandia stabilized zirconia hydrogen fuel cells. Several studies have asserted the strong repulsion (SSZ) since it shows high oxygen ionic conductance in comparison to between these two species on the solid surface, especially in high pressures, commonly used ytrria stabilized zirconia (YSZ) in SOFCs. We have used wherein the formation of homogeneous islands of CO have been reported. oxygen plasma assisted molecular beam epitaxy (OPA-MBE) to synthesize On the other hand, theoretical work specifically addressing the H/CO high quality SSZ thin films on sapphire (0001) substrates and systematically coadsorption system on Pt is rather limited. To fully understand the physical investigated the conductivity as a function of temperature and Sc mechanisms involved at the atomic scale, it would be beneficial for concentration. The epitaxial films have been characterized using various example to quantify the extent to which H and CO interaction on Pt is surface and bulk sensitive capabilities to determine their structure and repulsive, knowing that H-CO interaction in the gas phase is actually partly composition. The ionic conductivity of SSZ depends not only on the dopant attractive, and comment on possibilities for H and CO closely coexisting on concentration, but also on the crystalline structure of the thin films. The Pt. It is in this light that we in this study describe the behavior of hydrogen optimum Sc dopant concentration for the highest conductivity was observed near a Pt surface-adsorbed carbon monoxide molecule using a potential as 18 cation % in the temperature range of 500-900 °C. Conductivity energy term constructed from ab initio calculations. The considerable appears to be significantly high in high quality cubic SZZ films in asymmetry of the repulsion extent around CO suggests that while incoming comparison to mixed phases of cubic and monoclinic. Molecular dynamics hydrogen experiences strong obstacles to adsorption even before the Pt simulations of oxygen diffusion in cubic SZZ between 1125 and 2500 K surface is reached, adsorbed H can remain stable even in relatively compact show that the oxygen vacancy has no preference between Sc and Zr first conditions. Inhibiting effects of CO greater than what is expected from neighbors, but the activation energy for O diffusion changes with Sc dopant simple adsorption site exclusion are discussed with regard to concentration. Insights into the role of Sc dopant concentration on adsorption/desorption and mobility on platinum, as well as possibilities of conductivity of SZZ obtained from experiments and simulations will be COH and HCO formation on platinum. A quantum mechanical treatment of presented the H atom behavior similar to what we have used before1 is also performed on the obtained potential term. Theoretical results are lastly discussed with EN-TuP6 Chemical Mechanical Polishing Characteristics of CdS for available experimental data on the H-CO coadsorbate system on transition CdS/CdTe Thin Film Solar Cell Applications, H.-Y. Na, J.-S. Park, P.-J. metal surfaces. Ko, Chosun University, Korea, N.-H. Kim, Chonnam National University, 1 T. Roman, H. Nakanishi, W. A. Diño, H. Kasai, e-J. Surf. Sci. Nanotech. 4 (2006) 619. Korea, J.-T. Yang, Gwangju College of Korea Polytechnic V, W.-S. Lee, Chosun University, Korea EN-TuP3 Electronic Energy Level Alignment in Dye Sensitized Oxide CdS is widely used for the window layer material for the various thin film Substrates, J.P. Theisen, S. Rangan, E. Bersch, R.A. Bartynski, J.D. Sorge, solar cells including CdS/CdTe, CdS/Cu2S, and CdS/CuInSe2 due to its D.P. Birnie, Z. Duan, Y. Lu, Rutgers University excellent permeability with band gap of 2.42 eV while CdTe is one of the most promising photovoltaic materials with a direct band gap of about 1.45 In dye-sensitized solar cell applications, the HOMO-LUMO gap of dye eV, high optical absorption coefficients, the low cost, high efficiency and molecules determines the useful portion of the solar spectrum, and charge stable performance. The surface morphology of window layer materials was transfer of photoexcited electrons to the substrate depends on the alignment well known to affect the performances including the gain in photocurrent by of the LUMO to the substrate conduction band edge. We have used direct increase of light scattering.1 Therefore the surface morphology of CdS thin and inverse photoemission to measure the occupied and unoccupied film as an window layer must be enhanced by the improved processes. electronic states of several dye-related molecules and determine their Sputtering method was employed for preparation of CdS thin film, but it alignment with the band edges of single crystal and nanostructured TiO2 showed the rough surface morphology. Chemical mechanical polishing and ZnO substrates. On well characterized rutile TiO2(110) and wurtzite 7 Tuesday Afternoon Poster Sessions (CMP) processing was firstly proposed for improving the surface EN-TuP10 Photoconduction Properties of Titanium Dioxide Films morphology of CdS thin film on behalf of the plasma treatment reported in Prepared by Reactive Magnetron Sputtering, H.A. Shukur, Kogakuin some researches. Removal rate was estimated by the obtained results Univeristy, Japan, H. Nagai, I. Takano, M. Sato, Kogakuin University, through the application to Hernandez power law as a generalization version Japan of Preston's equation for a better description of removal rate. Surface Since TiO2 has been used as one of lower cost materials and is harmless to roughness and within-wafer non-uniformity (WIWNU%) of the sputtered the environment, it is expected to use as a material of a clean energy system CdS thin film was also examined with a change of CMP process parameters in future. Furthermore its photocatalysis have antifouling and antibacterial including table speed and down force. The optimized process condition was properties. At the same time, the electric property shows n-type selected considering to both the surface roughness and the hillock-free semiconductor characteristics and is classified as a high dielectric material. surface with the good uniformity. However, details of electric property for TiO2 have not been researched on 1 M. Phyton et al., J. Non-Cryst. Solids 2008. the relations between the oxygen deficit state and light. Generally the resistance of TiO2 is decreases by the excitation of electrons due to the light EN-TuP7 High Quality TCO Deposition using New DC Power irradiation. We anticipate that these properties are applied to a photo sensor Supplies, D. Ochs, HUETTINGER Elektronik GmbH + Co KG, Germany, of electronic parts. In this study the electrical property of TiO2 thin film was P. Ozimek, HUETTINGER Electronic Sp z o. o., Poland investigated under irradiation with the ultraviolet or visible light. The The main application of magnetron sputter processes for thin film solar cell formation conditions was changed the substrate temperature 100 and 200°C. production is the deposition of transparent conductive oxides (TCO). The Furthermore O2 flow rate was changed from 0.1 to 1.7 sccm for each most significant example for this TCO material class is ZnO:Al (AZO) substrate temperature. I-V property of films on a slide glass was measured which is of great importance as a transparent conductive layer for by using an unresisted current meter under fluorescence light (FL), a black photovoltaic applications. Since this material has an especially high arcing light (BL) or a sterilizing light (SL). The measurement size of the film was rate, pulsed DC power processes have been used for deposition in the past. 200nm in thickness, 10 mm in length and 8 mm in width. The resistivity of A new DC power supply family has been developed with the goal of films depends on O2 flow rate. On the other hand the films resistivities in replacing these pulsed DC processes with economic standard DC processes. both temperature conditions hadn't a large different property until 1.3 sccm, The most important feature of this power supply is an extremely fast and but the films formed under substrate temperature 200°C showed a large advanced arc management with the capability to run stable processes with resistvity. The microstructure of these films investigated by X-ray high arcing rates. The arc management has three different detection criteria: diffraction showed clearly that the both of O2 flow rate and substrate a voltage, a current and a combined voltage/current criteria. After detecting temperature affected films in crystalline structure. In case of high substrate an arc, a positive voltage is applied to the cable between the power supply temperature and large O2 flow rate, the crystalline structure of films and cathode. This so-called Cable Length Compensation compensates the changed to an anatase type and films resistivity was raised. The stored energy of the cable and reduces the energy supplied into the arc after measurement of photoconduction current under each light irradiation power shut off. In this way residual arc energies of less than 0.5 mJ/kW, are showed two important results. Firstly the TiO2 thin films obtained a large achievable. Stable processes over a long time with arcing rates of up to effect of photoconduction current under BL irradiation in all formation 20,000 arcs/s become possible. The fast arc management with adaptable conditions. The second point was that the photoconduction current reduced parameters results in superior film quality, and homogeneity of the with increase of the film resitivity and the maximum photoconduction deposited film. The new economic DC power supplies replace pulsed DC current was obtained at the film of 0.5 sccm with both of a substrate power without any disadvantages. temperature. 1 Akira Fujishima, Kazuhito Hashimoto and Toshiya Watanabe, "TiO2 Photocatalysis Fundamental and Applications". EN-TuP8 Vacuum Insulating Glass: Window of the Future, P.J. Petit, V-Glass LLC EN-TuP11 Effects of Pulse Sputtering Condition on Al: ZnO's This paper provides a brief summary of the past, present and potential near- Uniformities of TCO Properties for Solar Cell Application, W.K. Yang, term future of energy efficient windows, based on vacuum insulating glass, J.E. Jee, J.H. Joo, Kunsan National University, Korea for residential buildings. It presents a brief history of window technology to Bipolar pulsed magnetron sputtering is used to deposit Al doped ZnO on a the present day, summarizes known efforts around the world today to glass substrate for a TCO (transparent conducting oxide) in a solar cell develop improved insulating window technology, and describes a "Window structure. A 5"x25" AZO target was sputtered by 50 – 250 kHz bipolar of the Future"1 that might reasonably be assumed to be available in 2015. pulsed dc power supply to deposit 400x400mm area by swinging back and This "Window of the Future" consists of a Vacuum Insulating Glass (VIG) forth. Sheet resistance, surface morphology and optical transmittance were unit mounted in a low-heat-loss frame. Using a 3 ft by 5 ft window measured at 16 slide glasses (1"x3") to evaluate uniformity. In the thickness assembly as a representative "average" size for the purpose of this exercise, of 800nm, the average value of sheet resistance was 37Ω/□ and uniformity the overall U-value for a window of this design and size is estimated to be was 21.4% in 400×400mm area. The thickness of AZO thin film was about 0.091 Btu/hr-sq ft-°F, which is equivalent to a wall rated at R11. 800nm and the resistivity was 2.9×10-3 Ω•cm. Generally, magnetron Barriers which have prevented vacuum windows from being realized over sputtering plasma is thought to be well confined above a target's race track. the past two decades will be described, as well as the current strategies As substrate carrier is swinging, plasma is observed to be severely disrupted intended to overcome them. 1 to go around to the back side at 5cm of target-substrate distance. To fully "Window of the Future", Swing Research LLC, April, 2008. address these phenomena, we must use self consistent plasma model incorporating pulsed dc not just a simple dc cathode. As a first approach, we EN-TuP9 Characterization of the Photovoltaic Heterostructure analyzed gas flow using a 3D fluid model as a substrate carrier is moving CdS:F/CdSTe*, F. de Moure-Flores, M. Meléndez-Lira, J.G. Quiñones- around a target and a gas distribution pipe. In here, we found that the gas Galván, E. Mota-Pineda, S. Cerón-Gutiérrez, CINVESTAV-IPN, México, flow distribution affected the plasma. Also we thought that this plasma A. Hernández-Hernández, Escuela Superior de Fisica Matemáticas-IPN, might affect the deposited thin film. So, we expected that the uniform gas México, M. González-Alcudia, M. Zapata-Torres, CICATA-IPN Unidad flow distribution could improve the plasma uniformity and the Altamira, México, C. Davet-Lazos, M.delaL. Olvera, CINVESTAV-IPN, characteristics of AZO thin film. México We present results of the characterization of the structural, electronic and EN-TuP12 Germanium Nanowires: Applications in Photovoltaics and electrical properties of the photovoltaic heterostructure: ITO / CdS:F / Electronics, L.A. Klein, D.D.T. Mastrogiovanni, A. Du Pasquier, E. CdSTe. The ITO film was deposited by the technique of rf sputtering. The Garfunkel, Rutgers University CdS layer was deposited employing chemical bath deposition adding Single crystal germanium nanowires are grown via vapor-liquid-solid fluorine to increase n-type doping. The top CdSTe layer was deposited by methods in a hot-wall chemical vapor deposition reactor. We present the the modified laser ablation technique.1 The motivation to deposit a CdSTe results of nanowire growth and discuss potential applications of nanowires layer, instead just CdTe, is to limit the S interdiffusion at the CdS/CdTe grown on a variety of substrates. The relatively low growth temperature interface in order to improve the characteristics of the interfacial electric required for germanium nanowire formation combined with the enhanced field.2 We report the characteristic I vs. V, the spectral response, as well as semiconducting properties such as higher carrier mobility of germanium the efficiency of the photovoltaic heterostructure. These results are over silicon makes these wires an attractive building block in the rapidly correlated with those obtained from the chemical, structural and electronic expanding field of nanotechnology. In addition to our investigations into characterization obtained through EDX and X-ray diffraction and UV-Vis how growth conditions and substrates can affect the shape and orientation and Raman spectroscopies. of the nanowires, we have investigated various chemical passivation * 1 This work is partially supported by CONACyT-Mexico methods, including chlorination, H-termination, and thiol and alkene M. González-Alcudia, A. Márquez-Herrera, M. Zapata-Torres, M. Meléndez-Lira and O. passivation. Passivation becomes of utmost importance for germanium Calzadilla-Amaya, Adv. in Tech. of Mat. And Mat. Proc. J. 9, 81 (2007). 2 M.A. Santana-Aranda, M. Meléndez-Lira, Applied Surface Science, 175-176 (2000) 538-542. devices as germanium does not possess a stable native oxide as does silicon. These chemistries are also used to facilitate further surface functionalization Tuesday Afternoon Poster Sessions 8 and ohmic formation, and to improve device electrical performance. Most recently, the germanium nanowires were also used to enhance the properties of organic photovoltaic devices through the creation of a bulk heterojunction solar cell with poly(3-hexylthiophene) (P3HT). This hybrid- inorganic/organic device exhibits a significant increase in exciton dissociation and photocurrent when compared to pure P3HT. The photoelectrical properties of this device are characterized by measuring absorbance and photoluminescence spectra, current-voltage curves, and AM 1.5 filtered external quantum efficiency. In addition to the aforementioned techniques, other studies utilizing x-ray diffraction, Rutherford backscattering spectroscopy, and inductively coupled plasma mass spectroscopy enable us to observe how variations in nanowire concentration can affect the relative crystallinity and crystallite orientation of P3HT. We conclude with a discussion of our plans to improve the performance of these devices through surface passivation and the controlled introduction of phosphine impurities. 9 Tuesday Afternoon Poster Sessions Wednesday Morning, October 22, 2008 This research was supported in part by USDOE grant # DE-FG02-05ER84325 to Integrated Micro Energy Science and Technology Focus Topic Sensors, Inc. Room: 203 - Session EN+AS+EM+TF-WeM 9:00am EN+AS+EM+TF-WeM4 Improving Efficiencies of Electrochemical Storage Electrochemical Systems Through Microstructure Optimization, H.Y. Chen, University of Michigan, J.R. Wilson, P.W. Voorhees, Northwestern Moderator: S. Haile, Caltech, K. Thornton, University of University, S.B. Adler, University of Washington, S.A. Barnett, Michigan Northwestern University, K. Thornton, University of Michigan The properties and performance of a wide range of materials depend on 8:00am EN+AS+EM+TF-WeM1 Molybdenum Oxide Nanoparticles their microstructures. This is especially true in multifunctional, multiphase for Improved Lithium Ion Battery Technologies, A.C. Dillon, National or composite materials in which different phases perform different Renewable Energy Lab., S.-H. Lee, University of Colorado, Y.-H. Kim, functions. Therefore, controlling microstructures in these materials is one of National Renewable Energy Lab., R. Deshpande, Lam Research, P.A. the main routes for materials design to achieve optimal performance. Parilla, D.T. Gillaspie, E. Whitney, National Renewable Energy Lab., S.B. Various simulation methods that can be applied to examine processing, Zhang, Rensselaer Polytechnic Institute, A.H. Mahan, National Renewable property, and degradation during operation, including the phase-field Energy Lab. INVITED simulations and finite element modeling, will be discussed. Through coupling of simulations of microstructural evolution and transport that use Lithium-ion batteries are current power sources of choice for portable realistic microstructures, microstructural design for optimized performance electronics. Further improvement of performance and simultaneous is investigated. Specific examples will include microstructures found in reduction in cost could allow for the deployment in hybrid electric vehicles solid oxide fuel cell electrodes and those resulting from phase separation. or plug-in hybrid electric vehicles (PHEVs). The development of PHEVs will enable reduced oil consumption in the transportation sector. Importantly, PHEVs will also enable increased use of intermittent 9:20am EN+AS+EM+TF-WeM5 Layer-By-Layer Approaches to renewable energy resources such as solar and wind. By charging PHEVs Electrochemical Energy and Storage, P.T. Hammond, MIT INVITED during peak solar generation times, the load on the grid is effectively New advances in multilayer assembly have involved the development of "leveled", and the average output of coal-fired power plants will be ionically conductive multilayer thin films and the introduction of decreased. Recent efforts for electric vehicle applications are focused on electrochemical functionality. These systems have allowed the formation of new anode materials with slightly more positive insertion voltages to a range of ultrathin electrochemical devices including electrochromic minimize any risks of high-surface-area Li plating while charging at high displays, proton exchange membranes in fuel cells, and the use of these rates, a major safety concern. The state-of-the-art anode is graphite with a multilayers in other power and micropower devices. The use of this water reversible capacity of ~ 350 mAh/g and a potential of 0.1 V relative to based electrostatic assembly method has enabled the use of simple lithium metal. Metal oxides have long been known as Li-insertion processing conditions, such as salt content and solution pH, to act as tools compounds and typically operate at higher potential than graphite. for the manipulation of ion and electron transport characteristics in the film, Unfortunately they suffer from poor kinetics and/or capacity fade with as well as the morphology of these unique nano-assemblies. Examples of cycling, especially at higher rates. Hot-wire chemical vapor deposition has this approach include the ability to integrate highly water soluble polymers been employed as a scalable method for the deposition of crystalline metal with large sulfonic acid content into mechanically stable ultrathin films has oxide nanoparticles at high density. Under optimal synthesis conditions, led to new membranes with ionic conductivity approaching that of Nafion, only crystalline nanostructures with a smallest dimension of ~ 10 - 40 nm and methanol permeability two orders lower, thus lowering fuel crossover are observed. Anodes fabricated from crystalline MoO3 nanoparticles and leading to large enhancements in methanol fuel cell performance with display both an unprecedented reversible capacity of ~ 630 mAh/g and the application of nanometer thick thin films. On the other hand, the durable high rate capability. Porous thin film nanoparticle anodes, deposited incorporation of both organic and inorganic nanoscale objects using the by a simple electrophoresis technique, show no degradation in capacity for electrostatic assembly approach has enabled the incorporation of genetically 150 cycles when cycled at high rate (C/2 corresponding to one discharge in engineering virus biotemplates in collaborations with the Belcher research 2 hrs.). Micron sized MoO3 particles are shown to fail after several cycles, group that have resulted in new developments in battery electrodes, and the under the same conditions. Both x-ray diffraction and in situ Raman integration of titania and other materials systems for reactive electrodes. spectroscopy studies reveal that upon Li-ion insertion the crystalline Ultimately, the use of layer-by-layer systems have led to a range of organic nanoparticles become highly disordered. Density functional theory and inorganic materials systems that have incorporated metal oxide calculations elucidate the complex Li-ion insertion process and reveal a nanoparticles, semiconducting carbon elements, and organic polymers to novel mechanism confirming the nanoscale, high-rate, reversible capacity yield systems of interest for solar cells, capacitor/battery and despite the loss of structural order. The synthesis of these novel electrochemical energy electrode and separator applications. nanostructured materials and their potential for improving lithium-ion battery technologies will be discussed in detail. 10:40am EN+AS+EM+TF-WeM9 Material Solutions for Solid State Energy Storage, L.F. Nazar, University of Waterloo, Canada INVITED 8:40am EN+AS+EM+TF-WeM3 Boron Oxynitride: An Emerging The increasing demand for energy world-wide and inherent pressing Dielectric for High Temperature Capacitor Applications, N. Badi, S. environmental needs, have jump-started efforts to develop energy storage Vijayaraghavan, A. Bensaoula, University of Houston, A. Tempez, P. systems that can be coupled to renewable sources, and/or viable energy Chapon, Horiba Jobin Yvon, France, N. Tuccitto, A. Licciardello, conversion systems. Traditional electrode materials for lithium-ion storage University of Catania, Italy cells are typically crystalline, single-phase layered structures such as metal Among the many technical challenges encountered in the development of oxides, and graphitic carbons. These materials power billions of portable high temperature electronics, the role of a passive component like capacitor electronic devices in today's society. However, large-scale, high-capacity is very important. Dielectric integrity at temperatures greater than 250 °C storage devices capable of powering hybrid electric vehicles (HEV's) or has however, up till now, been one of the major impediments to bringing their plug-in versions (PHEV's and EV's) have much more demanding out a capacitor with suitable performance characteristics at these high requirements. This in turn, means that demands are on chemists to create temperatures. In this work, we investigate applicability of boron oxynitride novel materials, and address fundamental scientific issues relating to mass (BOxN1-x) thin films to fabricate capacitors for high temperature (ion) and electron transport at rapid rates. Recently, nanostructured solid applications. Deposited BOxN1-x layers by a filamentless ion source assisted state materials comprised of two more compositions, are being increasingly physical vapor deposition technique show a high thermal stability up to 400 exploited. These can take the form of "surface modified nanocrystallites", °C and a very high breakdown voltage (BDV) above 400 V/μm. BOxN1-x or stuffed nanoporous materials. For example, we employ porous samples of thickness varying from 70nm – 200nm were grown in a high frameworks as electrically conductive scaffolds to encapsulate active vacuum reactor. Prototype capacitors with boron oxynitride dielectric and electrode materials, where both components play a role in controlling the titanium metal electrodes have been fabricated on 3" Si wafers followed by electrochemical performance. This presentation will provide an overview of electrical and thermal characterization. Preliminary results indicate a very how the nanostructured approach provides benefit over the bulk, using small variation (~3%) of capacitance over the frequency range of 10 KHz – selected examples from a range of promising new solid state materials with 2 MHz and <10% variation in capacitance for the temperature range of 25 targeted, and tuneable structures. °C-400 °C. The device electrical characteristics studies (capacitance, leakage current, breakdown voltage), as a function of temperature and frequency for (BOxN1-x) dielectrics with varying oxygen to nitrogen ratio, are currently underway and their results will be presented at the conference. Wednesday Morning, October 22, 2008 10 11:20am EN+AS+EM+TF-WeM11 Platinum Nanorods as PEM Fuel Cell Electrodes, M. Gasda, R. Teki, T.-M. Lu, N. Koratkar, G. Eisman, D. Gall, Rensselaer Polytechnic Institute Platinum catalyst layers were deposited by magnetron sputtering from a variable deposition angle α onto gas diffusion layer (GDL) substrates and were tested as cathode electrodes in polymer electrolyte membrane (PEM) fuel cells. Layers deposited at normal incidence (α = 0°) are continuous, and approximately replicate the rough surface morphology of the underlying GDL. In contrast, glancing angle deposition (GLAD) with α = 85° and continuously rotating substrates yields highly porous layers consisting of vertical Pt nanorods. At 0.40 mg/cm2 total Pt loading, the rods are 100-500 nm long and ~300 nm wide, separated by 20-100 nm wide voids. The dramatic difference in microstructure is due to atomic shadowing during GLAD that causes Pt flux from highly oblique angles to preferentially deposit on surface protrusions, leading to nucleation and columnar growth on substrate mounds while surface depressions remain uncoated. Fuel cell testing at 70°C using Nafion 1135 membranes, Teflon-bonded Pt-black electrodes (TBPBE) at the anode, and atmospheric pressure hydrogen and air reactants shows a monotonic increase in performance of GLAD cathodes from 0.05 to 0.40 mg/cm2 total Pt loading. Nanorod cells exhibit approximately 2x higher mass activity than continuous layers at 0.50V (corrected for iR, shorting, and gas crossover); for example, GLAD and continuous layers with approximately the same Pt loading (0.18 and 0.25 mg/cm2, respectively) show 1.7 and 0.8 A/mg. In contrast, at low current density of 0.10 A/cm2, the continuous layers (0.70 V with 0.25 mg/cm2 Pt) outperform GLAD cells even with relatively high Pt loadings (0.65 V with 0.40 mg/cm2 Pt). The GLAD cells' higher mass-specific performance at high current densities is due to their high porosity which facilitates reactant transport, while the low-current performance of the continuous layer is attributed to a higher active Pt surface area. The sputter-deposited electrodes exhibit a higher platinum utilization in comparison to TBPBE reference cathodes, with GLAD cells (1.7 A/mg) performing better than TBPBE (0.75 A/mg) at high current densities (0.50 V), while continuous layers (0.07 A/mg) outperform TBPBE (0.035 A/mg) at 0.80 V. These results indicate the promise of nanoengineering to boost catalyst utilization in PEM fuel cells. 11 Wednesday Morning, October 22, 2008 Wednesday Afternoon, October 22, 2008 Energy Science and Technology Focus Topic perform experiments in situ, to follow specific chemical reactions and physical processes, and there is a need to be able to do this in multi- Room: 203 - Session EN+AS+TF+VT+NC-WeA dimensions, both spatial and temporal. We discuss and demonstrate the role of advanced electron microscopy in answering some of the most Energy: Tools and Approaches challenging and fundamental scientific questions in the field of catalysis, ranging from electron tomographic 3D reconstruction of the crystal facets Moderator: T.A. Dobbins, Louisiana Tech University and of catalyst nanoparticles and aberration-corrected imaging correlated with Grambling State University density functional theory for elucidating precise atomic positions, to in situ studies of catalytic reactions for visualization of otherwise unseen 1:40pm EN+AS+TF+VT+NC-WeA1 Continuous, In-Line Processing intermediate nanostructures. These examples relate the nanostructures of CdS/CdTe Devices, W.S. Sampath, Colorado State University, R.A. investigated to the property manifested by that particular structure, enabling Enzenroth, K.L. Barth, AVA Solar Inc., V. Manivannan, Colorado State us to gain new information about catalytic function. University, K. Barricklow, P. Noronha, AVA Solar Inc. INVITED A continuous, in-line process suitable for high throughput manufacturing of 3:00pm EN+AS+TF+VT+NC-WeA5 Investigation of Low CdS/CdTe photovoltaic devices has been demonstrated. Utilizing this Temperature-Annealed TiO2 Electrodes Prepared by Sol-Gel process, devices with efficiencies of 13% has been fabricated with a low Technique for the Fabrication of Dye-Sensitized Solar Cells, M.F. iron soda lime glass (3"x3") with ant-reflection coatings. The process has Hossain, S. Biswas, M. Shahjahan, A. Majumder, T. Takahashi, University been extended to large area devices (16" x16" substrate size). After CdCl2 of Toyama, Japan treatment, devices showed Voc > 700 mV and Jsc > 20 mA/cm2. This Dye sensitized solar cells (DSCs) are considered as a low cost alternative to performance is similar to the performance of small area devices which conventional p-n junction solar cell devices. The high light-to-energy showed good stability. Also we have employed many methods including conversion efficiencies achieved with dye sensitized solar cells (DSCs) may Spectroscopic Ellipsometry (SE) as a non-destructive tool to characterize be attributed to the nanoporous TiO2 electrode. Among the various CdS/CdTe heterojunction specifically studying the effects of processing on techniques for the preparation of TiO2 photo-electrode, the relatively simple the optical properties of the thin-film layers. sol gel method is the most widely used because of its ability to obtain films with tailored properties on large, curved substrates, and also it is a low 2:20pm EN+AS+TF+VT+NC-WeA3 Molecular Dynamics and temperature process. Crystallinity is one of the key factors behind the Experimental Investigations of Reversible Absorption of H2, CH4, and photovoltaic performances of TiO2; therefore achievement of better CO2 in Calixarenes, J.L. Daschbach, P.K. Thallapally, B.P. McGrail, L.X. crystallinity at relatively low temperature is an important issue. In our Dang, Pacific Northwest National Laboratory present study, the titanium dioxide porous films were deposited on SnO2:F Molecular solids based on calix[4]arenes have been shown to exhibit coated glass by sol–gel technique; where, an alcoholic solution of tetra- reversible absorption of small gas molecules, and remain stable, at buthylorthotitane was hydrolysed in a water/alcohol/acetic acid mixture. temperatures above 400 K. As such, they are interesting as prototypical These films were transparent and crack free. For this investigation; molecular systems for storing guests like hydrogen and methane, and annealing temperature and number of coating layers were varied. All the potentially selectively trapping carbon dioxide in hydrocarbon based films were annealed at different annealing temperatures, ranging from 350 systems. We have conducted high-pressure and temperature gas absorption to 500°C. Sufficiently good crystalline samples were obtained by annealing experiments with low density p-tert-butylcalix[4]arene (TBC4) in which at 350°C. The X-ray diffraction patterns of all TiO2 films confirmed the calixarenes are slightly offset to form a skewed capsule with an estimated anatase structure. The surface morphology of the films has been observed free volume of 235 Å3. Hydrogen and methane absorption near 300 K were by atomic force microscope and field emission scanning electron 1.0 and 2.2 wt% respectively. Carbon dioxide is absorbed at a 1:1 loading microscope. The morphology of TiO2 thin films strongly depends on per TBC4 molecule at 3 atm. In recent work we have shown that the high annealing temperatures and number of coatings. Incident photon-to-current density form of TBC4 will absorb CO2 at 3 atm, undergoing a phase conversion efficiency is calculated for all the solar cells with different TiO2 transformation in the process, and it can be reversibly cycled between these thin films to evaluate the economic viability of this technique. It has been states using moderate combinations of temperature and pressure. Somewhat observed that the photoelectric conversion efficiency of DSCs increases surprisingly, we have found that TBC4 can be loaded with up to two CO2 with the optimization of annealing temperature as well as with the increase per TBC4 molecule. We have used empirical molecular simulation of the numbers of layers. techniques to study the dynamics of CO2 and CH4 in TBC4. The rattling motion of the absorbed small molecules have been characterized using velocity autocorrelation. The coupling to the host lattice is probed by temperature dependent calculations. The effects of increased loading are studied up to the 2:1 loading of CO2, and clearly show differences in the host-guest coupling for molecules outside the cavities relative to the cage entrapped molecules. The free energy of absorption of CH4 and CO2 is studied under range of conditions by thermodynamic integration. These data support the experimental observations that these molecules can be reversibly absorbed at moderate pressures and temperatures. 2:40pm EN+AS+TF+VT+NC-WeA4 Sustainable Energy and the Role of Advanced Electron Microscopy, D.J. Stokes, B. Freitag, D.H.W. Hubert, FEI Company, The Netherlands Advanced electron microscopy, using the latest aberration-corrected and monochromated (scanning) transmission electron microscopes (S/TEM) is helping to bring new scientific and technological insights that are advancing progress in areas such as health, energy and the environment. Specifically, with global energy resources under increasing pressure, great efforts are being made to develop new nanomaterials that will lead to renewable energy sources and increased efficiency, to sustain energy supplies into the long term future whilst helping to preserve and protect the Earth's environment. To get there, we are being taken to atomic realms such that, to tailor new nanomaterials for specific functions, it is essential to precisely understand, accurately control and truly visualize structure-property relations at an unprecedented level. The atomic structure of nanomaterials and the energy needed for their function can be optimized by the fundamental understanding of catalytic behavior of nanoparticles and by a better understanding of the physical properties on the atomic level of systems such as solar cells, fuel cells and light sources (LEDs). This requires advanced tools that allow us to see down to the individual atoms and sense their chemical environment. It means having the ability to Wednesday Afternoon, October 22, 2008 12 Thursday Morning, October 23, 2008 Energy Science and Technology Focus Topic 9:00am EN+EM+NS+P+A+T+V-ThM4 Morphology Study of Room: 203 - Session EN+EM+NS+P+A+T+V-ThM Vacuum-Deposited Pentacene:C60 Mixed Thin Films for Photovoltaic Applications, J. Xue, Y. Zheng, J.D. Myers, J. Ouyang, University of Energy: Tools and Approaches Florida The efficiency of organic photovoltaic (PV) devices has gained steady Moderator: S.P. Williams, Plextronics, Inc. increase in past 20 years, showing a potential to provide clean and low-cost electrical energy in the near future. Bulk heterojunction (HJ) composed of 8:00am EN+EM+NS+P+A+T+V-ThM1 Nano-Structured and Micro- nanoscale percolation of donor and acceptor phase have been demonstrated Structured Semiconductors for Better Efficiency of Solar Cells, C.-F. to improve the efficiency of organic PV device. Such improvement is Lin, J.-S. Huang, S.-C. Shiu, J.-J. Chao, C.-Y. Hsiao, K.-H. Tsai, National attributed to the creation of a spatially distributed interface, which enhances Taiwan University INVITED exciton dissociation, and the presence of continuous conducting paths for The foreseeable depletion of fossil fuel and the global warming caused by efficient charge collection. However, ideal nanoscale percolation is not the carbon dioxide had led to the increasing attention of alternative readily achievable. Therefore, understanding the morphology inside the renewable energy, especially photovoltaic. Therefore, crystalline Si-PV bulk heterojuncion plays an important role on achieving efficient PV devices are quickly spreading. Unfortunately, the large consumption of Si device. Here, phase separation in donor-acceptor (D-A) mixture composed materials hinders their vast applications. Many efforts have been switched of pentacene:C60 and how it contributes to a percolated morphology are to developing thin-film PV devices. In this talk, we will discuss the use of studied. The pentacene:C60 mixed films are fabricated by co-deposition of nano-structured and micro-structured semiconductors that enable the two molecules with vacuum thermal evaporation (VTE) method. The fabrication of thin-film solar cells with improved efficiency. Several types mixing ratio of pentacene and C60 is controlled by varying the deposition of such thin-film solar cells will be discussed, including the organic- rate of each species. X-ray diffraction (XRD), scanning electron microscopy semiconductor-nanowire composite film, organic-semiconductor micro- (SEM) and atomic force microscopy (AFM) are used to characterize the structure composite film, nano-wire semiconductor thin film, and micro- vacuum deposited pentacene:C60 mixed film. XRD patterns of structured semiconductor thin film. In the thin-film solar cells using pentacene:C60 mixed films indicate phase separation inside the mixture, organic-semiconductor-nanorod composite film, different types of which is reflected by appearance of characteristic diffraction peaks of thin semiconductor nanowires such as ZnO, Si, and GaAs nanowires are used to film phase pentacene. SEM and AFM images reveal the change of surface replace the accepter-type organics for two purposes: increasing the electron morphology of the mixed films with varied mixing ratio and deposition rate, mobility and assisting the formation of nano-morphology for better inter suggesting different degree of phase separation inside. Base on these link between the donor organics and acceptor materials. The fabrication information, PV devices are fabricated and their performance is procedures of those nanowires as well as the formation of the organic- investigated. It is found that by suppressing the phase separation between semiconductor-nanowire composite film with controlled nano-morphology pentacene and C60 to nanoscale the PV performance is improved will be presented. For the other solar cells using nano-structured and micro- significantly. The open circuit voltage (Voc) and short circuit current (Jsc) structured semiconductors, we will particularly describe the technique of increase from 0.45 V and 9.7 µA/cm2 in pentacene:C60 = 1:1 (by weight) nanowire/micro-structure transfer. In our approach, the nanowires and device to 0.58 V and 1.3 mA/cm2 in pentacene:C60 = 1:5.5. All these micro-structures are made from the bulk semiconductors or epitaxial suggest that degree of phase separation of molecular mixtures can be semiconductors, so they will have much better crystal quality than the usual controlled by varying the process conditions, which may lead to new thin-film materials. In addition, after nanowires and micro-structures are pathways to generate nanoscale percolation for application in efficient transferred to other transparent substrates, the original wafer can be reused, organic PV devices. so the material cost can be lowered considerably. In addition, it offers the advantages of the bending flexibility, not being limited by the brittle 9:20am EN+EM+NS+P+A+T+V-ThM5 Tailoring the Morphology of property of semiconductors. Furthermore, in comparison with current III-V Organic Solar Cells with Surface Templates, S. O'Donnell, University of tandem solar cells taken by monolithic approach, which requires lattice Virginia and The MITRE Corporation, P. Reinke, University of Virginia match and current balance, our approach enables mechanically stacking. One of the most important applications of fullerenes is their incorporation in Thus each cell could be designed individually to match the entire solar organic solar cells, where they function as an electron acceptor in spectrum for optimal solar usage. Therefore, such new-type thin-film solar conjunction with photoactive molecules such as porphyrin. The photoyield cells are expected to be potentially efficient and low cost. is intimately linked to the morphology, which determines the efficiency of exciton diffusion and separation, and the effectiveness of charge transport to 8:40am EN+EM+NS+P+A+T+V-ThM3 Endohedral Metallofullerenes the electrodes. Control of the morphology across lengthscales, spanning the as Improved Acceptor Materials for Organic Solar Cells, M. Drees, range from the molecule to the several hundred nm, is critical to Luna Innovations Incorporated, R. Ross, Georgetown University, C. optimization of solar cell functionality. We control the morphology by Cardona, Luna Innovations Incorporated, E. Van Keuren, Georgetown using tailored substrate templates on which we assemble ultrathin films University, D. Guldi, Friedrich-Alexander-Universitat Erlangen-Nurnberg, with well-defined regions of acceptor and photoabsorber molecules. This Germany, B.C. Holloway, Luna Innovations Incorporated approach enables us to measure the morphology and interface structure with Cost factors in inorganic solar cells have opened up a new path to less atomic resolution with scanning probe methods, and to subsequently expensive manufacturing techniques using bulk heterojunction investigate the photocurrent distribution. A pattern with variable geometry polymer/fullerene based solar cells. Using empty cage fullerene derivatives is written on the surface of highly oriented pyrolitic graphite (HOPG), our as the acceptor material, state-of-the-art organic photovoltaics currently model surface, with a focussed ion beam (Ga+, 30 keV ion energy), which display ~5% overall conversion efficiency. One of the main factors limiting creates regions with a high density of surface defects interspaced with the efficiency in organic solar cells is the low open circuit voltage. The largely undamaged graphite surface. The surface defect structure, its open circuit voltage is governed by the molecular orbitals of the donor and extension and density within the pattern is characterized prior to molecule acceptor material; therefore better matching of the orbitals will lead to deposition. Surface defects interact strongly with the fullerene molecules, improved voltages. Here we present a novel acceptor material based on and thus provide nucleation centers for the formation of fullerene islands Trimetasphere® carbon nanomaterials (TMS). Trimetaspheres® are whose position is in registry with the artificial pattern. The boundary of the endohedral metallofullerenes that consist of a trimetal nitride cluster ion damaged region serves as the primary nucleation center for the enclosed in a C80 cage. First-generation Trimetasphere® carbon formation of C60 islands, whose shape is controlled by the pattern geometry nanomaterial derivatives have been synthesized and show behavior and the diffusion length of the molecules. We will describe how the consistent with C60 but with improved molecular orbitals. Electrochemical artificial pattern can be used to tailor the morphology across lengthscales data suggests a maximum voltage increase of up to 280 mV over C60- and discuss the extension of this method to other, technically relevant PCBM-based devices and photophysical characterization of shows efficient surfaces such as quartz which possesses a natural patterning in the form of and stable charge separation. Initial bulk-heterojunction devices have been ledges. The complete 2D nanostructure can be built by deposition of synthesized with open circuit voltages that are 280 mV higher than fullerene on the templated HOPG, and the remaining "empty" graphite reference devices using C60-PCBM and conversion efficiencies exceeding surface is then filled with photoabsorber molecules. We will show the 3.1%. movement of porphyrin molecules into the pattern, and how the interfacial region between fullerenes and porphyrins evolves, and discuss the resultant morphologies. This hierarchical assembly of organic solar cells will enable us to tailor morphologies and link them uniquely to the photophysical processes. 13 Thursday Morning, October 23, 2008 9:40am EN+EM+NS+P+A+T+V-ThM6 Photoemission Studies of Lead 11:20am EN+EM+NS+P+A+T+V-ThM11 Preparation of Nanoporous Sulfide Nanocrystals in Organic Films, A.T. Wroble, D.J. Asunskis, A.M. ZnO Photoelectrode using PEG Template for the Fabrication of Dye- Zachary, I.L. Bolotin, University of Illinois at Chicago, D.J. Wallace, M. Sensitized Solar Cells, M.F. Hossain, S. Biswas, M. Shahjahan, T. Severson, University of Wisonsin-Madison, L. Hanley, University of Takahashi, University of Toyama, Japan Illinois at Chicago Recently, great attention has been paid to dye-sensitized solar cells (DSCs) Lead sulfide (PbS) nanocrystals have shown potential for use in due to their low fabrication cost. The high light-to-energy conversion optoelectronic applications including photovoltaics. PbS nanocrystals are efficiencies achieved with dye sensitized solar cells (DSCs) may be grown directly into polymers or organic oligomer matrices to control the attributed to the nanoporous TiO2 electrode. Zinc oxide (ZnO) is a wide size and surface chemistry of the resulting nanocrystals. Transmission band gap semiconducting material with a similar band gap and electron electron microscopy is used to determine the size distribution of PbS affinity to those of TiO2 and has been considered as an alternative material nanocrystals in organic films grown by either colloidal synthesis in polymer in DSCs applications. Among the various techniques for the preparation of solutions or gaseous deposition using a cluster beam deposition source. ZnO photo-electrode, the relatively simple sol gel method is the most Both the colloidal and cluster beam deposition methods are described in widely used because of its ability to obtain films with tailored properties on detail. Various techniques in photoemission spectroscopy are then applied large, curved substrates. In our present study, the nanoporous ZnO films to these PbS nanocrystal-organic films. X-ray photoelectron spectroscopy were deposited on SnO2:F coated glass by sol–gel technique with (XPS) confirms that PbS nanocrystals are present. Soft-XPS using 200 eV polyethylene glycol (PEG) as organic template, Zn(CH3COO)2.2H2O as photon energies available at a synchrotron radiation source provides surface precursor, ethanol as solvent and NH(C2H2OH)2 as chelating agent. The sensitivity to observe the interaction of the PbS nanocrystal surface with the ZnO films have been characterized by the TG-DTA, XRD, SEM AFM, organic matrix and is compared to XPS results obtained using 1487 eV FTIR and UV-VIS systems. The surface morphology of the nanoporous photon energy. Little or no bonding between the PbS nanocrystals and the ZnO films strongly depend on the Zn(CH3COO)2 concentrations, PEG organic phase is observed. The core of the nanocrystals are found to be 1:1 contents and number of coatings. It was revealed from optical study that the Pb:S, but their surfaces are enriched in Pb. Finally, core level binding dye absorption increases with the increase of PEG concentrations. Incident energy shifts in XPS under simulated solar irradiation are used for contact- photon-to-current conversion efficiency is calculated for all the solar cells free evaluation of element-specific photovoltaic electrical response of these with different ZnO thin films to evaluate the economic viability of this PbS nanocrystal-organic thin films. technique. The variation of photoelectric conversion efficiency of the solar cells, deposited with different Zn(CH3COO)2 and PEG concentrations are 10:40am EN+EM+NS+P+A+T+V-ThM9 Rational Design of discussed with the analysis of different microstructure of the ZnO thin films Nanostructured Hybrid Materials for Photovoltaics, S.B. Darling, I. and the corresponding dye-incorporations. Botiz, Argonne National Laboratory, S. Tepavcevic, S.J. Sibener, The University of Chicago, T. Rajh, N. Dimitrijevic, Argonne National 11:40am EN+EM+NS+P+A+T+V-ThM12 Metal / Polymer Interfaces: Laboratory Ca on Polyfluorenes, J.A. Farmer, J.H. Baricuatro, University of Efficient conversion of photons to electricity in organic and hybrid Washington, E. Zillner, Universitaet Erlangen-Nuernberg, Germany, J.F. materials depends on optimization of factors including light absorption, Zhu, University of Science and Technology of China, C.T. Campbell, exciton separation, and charge carrier migration. Bulk heterojunction University of Washington devices target these processes, but disorder on the nanoscale results in Conjugated polymers are being investigated for use in organic photovoltaic inefficiencies due to exciton recombination and poor mobility. By rationally devices and organic electronics due to favorable cost and ease of processing designing the morphology at appropriate length scales, one can enhance the compared to devices based on inorganic materials. The synthetic tunability effectiveness of internal processes and, therefore, the performance of of polymer-based devices makes them applicable to many technological photovoltaic devices. In this work, we have implemented this approach in applications. The creation of cheap organic photovoltaic devices would two hybrid material systems—both of which may provide pathways to low- significantly improve our ability to harness solar energy and curb the use of cost, large-area fabrication.1 The first involves a rod-coil block copolymer fossil fuels. The development of organic LED and organic electronics may which is used both as an optoelectronically active material and as a give rise to flexible computer displays and hardware that could structure-directing agent to pattern active material into ordered revolutionize human interaction with computing devices. Crucial to the nanostructures. The second system uses electrochemically prepared titania performance optimization of these devices is understanding the interaction nanotube arrays in concert with in situ polymerization of electron-donating between the metal electrodes and the polymer. The structure and energetics material. In both cases, the characteristic donor-acceptor length scale is of the interface between Ca and two polyfluorenes, poly(9,9-di-n- controlled to be comparable to the exciton diffusion length throughout the hexylfluorenyl-2,7-diyl) (PDHF) and poly(9,9-di-n-hexylfluorenyl-2,7- active layer, and the domains are oriented perpendicular to the incident light vinylene) (PDHFV), were studied in ultrahigh vacuum using adsorption direction to encourage efficient charge migration. microcalorimetry, and low-energy ion scattering spectroscopy. The initial 1 Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office sticking probabilities of Ca on pristine PDHF and PDHFV at 300 K were of Science, Office of Basic Energy Sciences, under Contract #DE-AC02-06CH11357. Parts of this 0.40 and 0.53, respectively. The sticking probability of Ca on PDHFV work were also supported by the NSF-MRSEC at the University of Chicago. began decreasing after ~0.06 ML, and then increased toward unity after ~0.24 ML. Because no similar behavior was seen on PDHF, this decrease in 11:00am EN+EM+NS+P+A+T+V-ThM10 Electronic Energy Level the Ca sticking probability on PDHFV is tentatively ascribed to the Alignment in Dye Sensitized Oxide Surfaces, S. Rangan, J.P. Theisen, E. presence of the vinyl group. At submonolayer coverages on both polymers, Bersch, R.A. Bartynski, Rutgers University the integrated Ca ISS peak area increased slowly below 1 ML, with a value We have used direct and inverse photoemission to measure the occupied less than 1 % of a saturated Ca surface at 300 K. These results indicated that and unoccupied electronic states of N3 dye and determine their alignment most of the Ca at low coverages were below the surface, and not visible to with the band edges of single crystal and nanostructured TiO2 and ZnO ISS. Beyond 1 ML the Ca peak area increased, and ultimately a continuous substrates. In dye-sensitized solar cell applications, the HOMO-LUMO gap Ca film formed at ~50 ML. Based on the variation of Ca peak area with of the dye molecule determines the useful portion of the solar spectrum, and coverage, Ca grows as 3D islands on these polymer surfaces. The heat of charge transfer of photoexcited electrons to the substrate depends on the adsorption of Ca on PDHF at 300 K was initially 240 kJ/mol and 315 alignment of the LUMO to the substrate conduction band edge. We have kJ/mol on PDHFV. The heat of adsorption of Ca on PDHF decreased to the compared the N3 dye properties on well characterized rutile TiO2(110) and heat of sublimation of Ca in ~0.25 ML; the heat of sublimation was reached wurtzite ZnO single crystal surfaces to adsorption on more technologically by ~0.50 ML for PDHFV. The interesting thermodynamic and sticking relevant TiO2 anatase nanoparticle and ZnO nanorod substrates. Samples behavior below 0.50 ML, where Ca is interacting strongly with specific were prepared and passivated with a pivalate layer in UHV, then sensitized adsorption sites on the polymer will be discussed, and related to the use of ex-situ in a solution of N3 dye in acetonitrile. STM measurements show that these polyfluorenes in device applications. the pivalic acid forms an ordered overlayer on the TiO2(110) surface and that the N3 dye molecules can be imaged after sensitization. For N3 on TiO2(110) as shown below, our spectroscopic measurements show that passivation significantly reduces contamination (presumably from water in the ambient) and that the N3 HOMO occurs at 0.9 eV above the TiO2 valence band edge, while the LUMO is found 0.5 eV above the conduction band edge. On ZnO , the N3 HOMO occurs at 1.3 eV above the ZnO valence band edge but the N3 LUMO occurs 2.1 eV above the conduction band edge, much higher than what is measured on TiO2. Comparison with experimental and theoretical values from the literature will be discussed. Thursday Morning, October 23, 2008 14 Authors Index Bold page numbers indicate the presenter — A — Gasda, M.: EN+AS+EM+TF-WeM11, 11 Gillaspie, D.T.: EN+AS+EM+TF-WeM1, 10 Mucherie, S.: EN+BI+SS+SE-TuM1, 3 Mukerjee, S.: EN+BI+SS+SE-TuM6, 3 Adler, S.B.: EN+AS+EM+TF-WeM4, 10 González-Alcudia, M.: EN-TuP9, 8 Myers, J.D.: EN+EM+NS+P+A+T+V-ThM4, 13 Asunskis, D.J.: EN+EM+NS+P+A+T+V-ThM6, 14 Graham, M.E.: EN+BI+SS+SE-TuM5, 3 Gray, K.A.: EN+BI+SS+SE-TuM5, 3 — N — — B — Guldi, D.: EN+EM+NS+P+A+T+V-ThM3, 13 Na, H.-Y.: EN-TuP6, 7 Nachimuthu, P.: EN-TuP1, 7; EN-TuP5, 7 Baber, A.E.: EN+BI+SS+SE-TuM11, 3 Gupta, S.: EN-TuP1, 7 Nagai, H.: EN-TuP10, 8 Badi, N.: EN+AS+EM+TF-WeM3, 10 Baricuatro, J.H.: EN+EM+NS+P+A+T+V-ThM12, — H — Nakanishi, H.: EN-TuP2, 7 Haagsma, J.: EN+SE+NS+SS-MoA3, 1 Nazar, L.F.: EN+AS+EM+TF-WeM9, 10 14 Hall, A.J.: EN+EM+NS+PS-TuA10, 6 Nicholas, R.J.: EN+EM+NS+PS-TuA5, 5 Barnett, S.A.: EN+AS+EM+TF-WeM4, 10 Hammond, P.T.: EN+AS+EM+TF-WeM5, 10 Nijem, N.: EN+SE+NS+SS-MoA11, 2 Barricklow, K.: EN+AS+TF+VT+NC-WeA1, 12 Han, S.M.: EN+EM+NS+PS-TuA4, 5 Noronha, P.: EN+AS+TF+VT+NC-WeA1, 12 Barth, K.L.: EN+AS+TF+VT+NC-WeA1, 12 Hanley, L.: EN+EM+NS+P+A+T+V-ThM6, 14 Norskov, J.K.: EN+BI+SS+SE-TuM9, 3 Bartynski, R.A.: EN+EM+NS+P+A+T+V-ThM10, 14; EN-TuP3, 7 Harrower, C.T.: EN+SE+NS+SS-MoA3, 1 Hebert, D.: EN+EM+NS+PS-TuA10, 6 — O — Bensaoula, A.: EN+AS+EM+TF-WeM3, 10 Ochs, D.: EN-TuP7, 8 Herbst, J.F.: EN+SE+NS+SS-MoA1, 1 Bera, D.: EN-TuP4, 7 O'Donnell, S.: EN+EM+NS+P+A+T+V-ThM5, 13 Hernández-Hernández, A.: EN-TuP9, 8 Bersch, E.: EN+EM+NS+P+A+T+V-ThM10, 14; Olvera, M.delaL.: EN-TuP9, 8 Holloway, B.C.: EN+EM+NS+P+A+T+V-ThM3, EN-TuP3, 7 Ophus, C.: EN+SE+NS+SS-MoA3, 1 13 Birnie, D.P.: EN-TuP3, 7 Ouyang, J.: EN+EM+NS+P+A+T+V-ThM4, 13 Holloway, P.H.: EN-TuP4, 7 Biswas, S.: EN+AS+TF+VT+NC-WeA5, 12; Ozimek, P.: EN-TuP7, 8 Hossain, M.F.: EN+AS+TF+VT+NC-WeA5, 12; EN+EM+NS+P+A+T+V-ThM11, 14 Bolotin, I.L.: EN+EM+NS+P+A+T+V-ThM6, 14 EN+EM+NS+P+A+T+V-ThM11, 14 — P — Hrbek, J.: EN+BI+SS+SE-TuM12, 4 Parilla, P.A.: EN+AS+EM+TF-WeM1, 10 Botiz, I.: EN+EM+NS+P+A+T+V-ThM9, 14 Hsiao, C.-Y.: EN+EM+NS+P+A+T+V-ThM1, 13 Park, J.-S.: EN-TuP6, 7 — C — Huang, J.-S.: EN+EM+NS+P+A+T+V-ThM1, 13 Petit, P.J.: EN-TuP8, 8 Campbell, C.T.: EN+EM+NS+P+A+T+V-ThM12, Hubert, D.H.W.: EN+AS+TF+VT+NC-WeA4, 12 Prasad, S.: EN-TuP1, 7 14 — J — Puerta, J.M.: EN+SE+NS+SS-MoA2, 1 Cardona, C.: EN+EM+NS+P+A+T+V-ThM3, 13 Carroll, M.S.: EN+EM+NS+PS-TuA4, 5 Jee, J.E.: EN-TuP11, 8 — Q — Jiang, W.: EN-TuP5, 7 Qian, L.: EN-TuP4, 7 Cederberg, J.G.: EN+EM+NS+PS-TuA4, 5 Joo, J.H.: EN-TuP11, 8 Quiñones-Galván, J.G.: EN-TuP9, 8 Cerda, J.I.: EN+SE+NS+SS-MoA2, 1 Cerón-Gutiérrez, S.: EN-TuP9, 8 — K — — R — Chabal, Y.J.: EN+SE+NS+SS-MoA10, 2; Kasai, H.: EN-TuP2, 7 Rajh, T.: EN+EM+NS+P+A+T+V-ThM9, 14 EN+SE+NS+SS-MoA11, 2 Kasemo, B.: EN+SE+NS+SS-MoA5, 1 Ramaker, D.E.: EN+BI+SS+SE-TuM6, 3 Chao, J.-J.: EN+EM+NS+P+A+T+V-ThM1, 13 Kelly, S.T.: EN+SE+NS+SS-MoA5, 1 Rangan, S.: EN+EM+NS+P+A+T+V-ThM10, 14; Chapon, P.: EN+AS+EM+TF-WeM3, 10 Kim, D.-H.: EN+EM+NS+PS-TuA3, 5 EN-TuP3, 7 Chaudhuri, S.: EN+SE+NS+SS-MoA10, 2 Kim, H.S.: EN+BI+SS+SE-TuM1, 3 Reinke, P.: EN+EM+NS+P+A+T+V-ThM5, 13 Chen, H.Y.: EN+AS+EM+TF-WeM4, 10 Kim, N.-H.: EN-TuP6, 7 Rockett, A.: EN+EM+NS+PS-TuA10, 6 Chen, L.: EN+BI+SS+SE-TuM5, 3 Kim, T.: EN+EM+NS+PS-TuA3, 5 Rodriguez, J.A.: EN+BI+SS+SE-TuM12, 4 Chopra, I.S.: EN+SE+NS+SS-MoA10, 2 Kim, Y.-H.: EN+AS+EM+TF-WeM1, 10 Roman, T.: EN-TuP2, 7 Clemens, B.M.: EN+SE+NS+SS-MoA5, 1 Klein, L.A.: EN-TuP12, 8 Ross, R.: EN+EM+NS+P+A+T+V-ThM3, 13 — D — Ko, P.-J.: EN-TuP6, 7 Koratkar, N.: EN+AS+EM+TF-WeM11, 11 Ryu, S.H.: EN+EM+NS+PS-TuA3, 5 Dang, L.X.: EN+AS+TF+VT+NC-WeA3, 12 Krishnan, R.: EN+SE+NS+SS-MoA9, 2 — S — Darling, S.B.: EN+EM+NS+P+A+T+V-ThM9, 14 Sampath, W.S.: EN+AS+TF+VT+NC-WeA1, 12 Kuchibhata, S.V.N.T.: EN-TuP1, 7 Daschbach, J.L.: EN+AS+TF+VT+NC-WeA3, 12 Santos, B.: EN+SE+NS+SS-MoA2, 1 Kuchibhatla, S.V.N.T.: EN-TuP5, 7 Davet-Lazos, C.: EN-TuP9, 8 Saoudi, M.: EN+SE+NS+SS-MoA3, 1 de la Figuera, J.: EN+SE+NS+SS-MoA2, 1 — L — Saraf, L.V.: EN-TuP1, 7; EN-TuP5, 7 de Moure-Flores, F.: EN-TuP9, 8 Langhammer, C.: EN+SE+NS+SS-MoA5, 1 Sato, M.: EN-TuP10, 8 DeSario, P.A.: EN+BI+SS+SE-TuM5, 3 Lee, S.-H.: EN+AS+EM+TF-WeM1, 10 Scott, F.J.: EN+BI+SS+SE-TuM6, 3 Deshpande, R.: EN+AS+EM+TF-WeM1, 10 Lee, W.-S.: EN-TuP6, 7 Setthapun, W.: EN+BI+SS+SE-TuM1, 3 Devanathan, R.: EN-TuP5, 7 Leonhardt, D.: EN+EM+NS+PS-TuA4, 5 Severson, M.: EN+EM+NS+P+A+T+V-ThM6, 14 Dillon, A.C.: EN+AS+EM+TF-WeM1, 10 Li, J.: EN+SE+NS+SS-MoA11, 2 Shahjahan, M.: EN+AS+TF+VT+NC-WeA5, 12; Dimitrijevic, N.: EN+EM+NS+P+A+T+V-ThM9, Libera, J.A.: EN+BI+SS+SE-TuM1, 3 EN+EM+NS+P+A+T+V-ThM11, 14 14 Licciardello, A.: EN+AS+EM+TF-WeM3, 10 Sheng, J.: EN+EM+NS+PS-TuA4, 5 Dobbins, T.A.: EN+SE+NS+SS-MoA9, 2 Lin, C.-F.: EN+EM+NS+P+A+T+V-ThM1, 13 Shiu, S.-C.: EN+EM+NS+P+A+T+V-ThM1, 13 Drees, M.: EN+EM+NS+P+A+T+V-ThM3, 13 Liu, P.: EN+BI+SS+SE-TuM12, 4 Shukur, H.A.: EN-TuP10, 8 Du Pasquier, A.: EN-TuP12, 8 Lu, T.-M.: EN+AS+EM+TF-WeM11, 11 Shutthanandan, V.: EN-TuP1, 7; EN-TuP5, 7 Duan, Z.: EN-TuP3, 7 Lu, Y.: EN-TuP3, 7 Sibener, S.J.: EN+EM+NS+P+A+T+V-ThM9, 14 — E — — M — Siebentritt, S.: EN+EM+NS+PS-TuA8, 5 Sorge, J.D.: EN-TuP3, 7 Eisman, G.: EN+AS+EM+TF-WeM11, 11 Ma, S.: EN+BI+SS+SE-TuM12, 4 Stair, P.C.: EN+BI+SS+SE-TuM1, 3 Elam, J.W.: EN+BI+SS+SE-TuM1, 3 Mahan, A.H.: EN+AS+EM+TF-WeM1, 10 Stokes, D.J.: EN+AS+TF+VT+NC-WeA4, 12 Emziane, M.: EN+EM+NS+PS-TuA5, 5 Majumder, A.: EN+AS+TF+VT+NC-WeA5, 12 Sutter, P.: EN+SE+NS+SS-MoA7, 1 Engelhard, M.H.: EN-TuP1, 7; EN-TuP5, 7 Manivannan, V.: EN+AS+TF+VT+NC-WeA1, 12 Sykes, E.C.H.: EN+BI+SS+SE-TuM11, 3 Enzenroth, R.A.: EN+AS+TF+VT+NC-WeA1, 12 Marina, O.: EN-TuP5, 7 — F — Marshall, C.L.: EN+BI+SS+SE-TuM1, 3 — T — Maslov, S.: EN-TuP4, 7 Takahashi, T.: EN+AS+TF+VT+NC-WeA5, 12; Farmer, J.A.: EN+EM+NS+P+A+T+V-ThM12, 14 Mastrogiovanni, D.D.T.: EN-TuP12, 8 EN+EM+NS+P+A+T+V-ThM11, 14 Freitag, B.: EN+AS+TF+VT+NC-WeA4, 12 McCarty, K.F.: EN+SE+NS+SS-MoA2, 1 Takano, I.: EN-TuP10, 8 Fritzsche, H.: EN+SE+NS+SS-MoA3, 1 McGrail, B.P.: EN+AS+TF+VT+NC-WeA3, 12 Teki, R.: EN+AS+EM+TF-WeM11, 11 — G — Meléndez-Lira, M.: EN-TuP9, 8 Tempez, A.: EN+AS+EM+TF-WeM3, 10 Gall, D.: EN+AS+EM+TF-WeM11, 11 Mitlin, D.: EN+SE+NS+SS-MoA3, 1 Tepavcevic, S.: EN+EM+NS+P+A+T+V-ThM9, Garfunkel, E.: EN-TuP12, 8 Mota-Pineda, E.: EN-TuP9, 8 14 15 Author Index Thallapally, P.K.: EN+AS+TF+VT+NC-WeA3, 12 Vijayaraghavan, S.: EN+AS+EM+TF-WeM3, 10 Yoo, W.J.: EN+EM+NS+PS-TuA3, 5 Theisen, J.P.: EN+EM+NS+P+A+T+V-ThM10, Voorhees, P.W.: EN+AS+EM+TF-WeM4, 10 Yu, Z.Q.: EN-TuP5, 7 14; EN-TuP3, 7 — W — Yudasaka, M.: EN+BI+SS+SE-TuM3, 3 Thevuthasan, S.: EN-TuP1, 7; EN-TuP5, 7 Thornton, K.: EN+AS+EM+TF-WeM4, 10 Wallace, D.J.: EN+EM+NS+P+A+T+V-ThM6, 14 — Z — Wang, C.M.: EN-TuP5, 7 Zachary, A.M.: EN+EM+NS+P+A+T+V-ThM6, Tierney, H.L.: EN+BI+SS+SE-TuM11, 3 Whitney, E.: EN+AS+EM+TF-WeM1, 10 14 Tsai, K.-H.: EN+EM+NS+P+A+T+V-ThM1, 13 Wilson, J.R.: EN+AS+EM+TF-WeM4, 10 Zapata-Torres, M.: EN-TuP9, 8 Tuccitto, N.: EN+AS+EM+TF-WeM3, 10 Wroble, A.T.: EN+EM+NS+P+A+T+V-ThM6, 14 Zhang, S.B.: EN+AS+EM+TF-WeM1, 10 — V — — X — Zheng, Y.: EN+EM+NS+P+A+T+V-ThM4, 13 van de Sanden, M.C.M.: EN+EM+NS+PS-TuA1, 5 Zhu, J.F.: EN+EM+NS+P+A+T+V-ThM12, 14 Xue, J.: EN+EM+NS+P+A+T+V-ThM4, 13 Van Keuren, E.: EN+EM+NS+P+A+T+V-ThM3, Zillner, E.: EN+EM+NS+P+A+T+V-ThM12, 14 13 — Y — Zoric, I.: EN+SE+NS+SS-MoA5, 1 Vandervelde, T.E.: EN+EM+NS+PS-TuA4, 5 Yang, C.: EN+EM+NS+PS-TuA3, 5 Veyan, J.-F.: EN+SE+NS+SS-MoA10, 2; Yang, J.-T.: EN-TuP6, 7 EN+SE+NS+SS-MoA11, 2 Yang, W.K.: EN-TuP11, 8 Author Index 16
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