Advanced Materials

Cover image for Vol. 23 Issue 20

Special Issue: Special Issue: Materials Research at the University of California, Santa Barbara

May 24, 2011

Volume 23, Issue 20

Pages 2247–2383

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Materials Research at UCSB: (Adv. Mater. 20/2011) (page 2247)

      Article first published online: 24 MAY 2011 | DOI: 10.1002/adma.201190071

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      This Special Issue presents a selection of the cutting-edge materials science research carried out at the University of California, Santa Barbara. The issue contains one Progress Report, three Research News articles and seventeen Communications with contributions from the departments Materials, Mechanical Engineering, Chemistry and Biochemistry, Physics, Electrical and Computer Engineering, Chemical Engineering, Molecular Biology, and Cellular and Developmental Biology and various institutes, research centers, and external collaborators, which clearly reflects the wide scope and multidisciplinary nature of materials research at UCSB.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Ordered Films for Solar Cells: Structural Order in Bulk Heterojunction Films Prepared with Solvent Additives (Adv. Mater. 20/2011) (page 2248)

      James T. Rogers, Kristin Schmidt, Michael F. Toney, Edward J. Kramer and Guillermo C. Bazan

      Article first published online: 24 MAY 2011 | DOI: 10.1002/adma.201190072

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      Solvent additives are shown to drastically affect internal ordering of the polymeric component of bulk heterojunction solar cells. Grazing incidence wide angle X-ray scattering measurements reveal that additives affect polymeric crystallite type, perfection, orientation, and population within the film. Gui Bazan, Ed Kramer, and co-workers demonstrate on p. 2284 that improvements in device performance that result from additive processing are well correlated with increases in the population of crystallites within the film of the type capable of π–π stacking.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Contents: (Adv. Mater. 20/2011) (pages 2249–2255)

      Article first published online: 24 MAY 2011 | DOI: 10.1002/adma.201190073

  4. Editorial

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. You have free access to this content
      Materials Research at the University of California, Santa Barbara (pages 2256–2259)

      David H. Auston, Glenn H. Fredrickson, Craig J. Hawker, Daniel E. Morse, Tresa M. Pollock, Ram Seshadri and Guillermo C. Bazan

      Article first published online: 24 MAY 2011 | DOI: 10.1002/adma.201101196

  5. Progress Report

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Nanoscale Assembly in Biological Systems: From Neuronal Cytoskeletal Proteins to Curvature Stabilizing Lipids (pages 2260–2270)

      Cyrus R. Safinya, Uri Raviv, Daniel J. Needleman, Alexandra Zidovska, Myung Chul Choi, Miguel A. Ojeda-Lopez, Kai K. Ewert, Youli Li, Herbert P. Miller, Joel Quispe, Bridget Carragher, Clinton S. Potter, Mahn Won Kim, Stuart C. Feinstein and Leslie Wilson

      Article first published online: 20 APR 2011 | DOI: 10.1002/adma.201004647

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      Supramolecular structures of bundles and loop-like networks of microtubules in the presence of counterions (blue/red spheres comprise the tubule wall), and nanorods and nanotubes of block liposomes comprised of charged curvature-stabilizing-lipids (green/yellow), determined by synchrotron X-ray scattering and electron microscopy including cryogenic TEM. The distinct microtubule bundles and lipid nanotubes and nanorods have applications in nanotechnology and biotechnology.

  6. Frontispiece

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Bulk Heterojunction Solar Cells with Large Open-Circuit Voltage: Electron Transfer with Small Donor-Acceptor Energy Offset (Adv. Mater. 20/2011) (page 2271)

      Xiong Gong, Minghong Tong, Fulvio G. Brunetti, Junghwa Seo, Yanming Sun, Daniel Moses, Fred Wudl and Alan J. Heeger

      Article first published online: 24 MAY 2011 | DOI: 10.1002/adma.201190074

  7. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Bulk Heterojunction Solar Cells with Large Open-Circuit Voltage: Electron Transfer with Small Donor-Acceptor Energy Offset (pages 2272–2277)

      Xiong Gong, Minghong Tong, Fulvio G. Brunetti, Junghwa Seo, Yanming Sun, Daniel Moses, Fred Wudl and Alan J. Heeger

      Article first published online: 1 MAR 2011 | DOI: 10.1002/adma.201003768

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      Photoinduced electron transfer is observed in polymer bulk heterojunction solar cells with very small interfacial energy offset. The results imply that open circuit voltage values close to the band gap of the semiconducting polymer should be possible for polymer bulk heterojunction solar cells just as for inorganic solar cells.

    2. Correlated Compositions, Structures, and Photoluminescence Properties of Gallium Nitride Nanoparticles (pages 2278–2283)

      Birgit Schwenzer, Jerry Hu and Daniel E. Morse

      Article first published online: 18 JAN 2011 | DOI: 10.1002/adma.201003750

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      Introducing nitrogen vacancies into gallium nitride nanoparticles might allow tuning optoelectronic properties. Comparing experimental and theoretical data establishes that an observed broad chemical shift distribution in 71Ga MAS NMR spectra results from chemical inhomogeneities at the atomic level within GaN nanoparticles, which can be correlated with the intensity of blue band edge related photoluminescence.

    3. Structural Order in Bulk Heterojunction Films Prepared with Solvent Additives (pages 2284–2288)

      James T. Rogers, Kristin Schmidt, Michael F. Toney, Edward J. Kramer and Guillermo C. Bazan

      Article first published online: 18 JAN 2011 | DOI: 10.1002/adma.201003690

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      Solvent additives are shown to drastically affect internal ordering of the polymeric component of bulk heterojunction solar cells. Grazing incidence wide angle x-ray scattering measurements reveal that additives affect polymeric crystallite type, perfection, orientation, and population within the film. Improvements in device performance that result from additive processing are well correlated with increases in the population of crystallites within the film of the type capable of π–π stacking.

    4. Solution-Processed Nanostructured Benzoporphyrin with Polycarbonate Binder for Photovoltaics (pages 2289–2293)

      Sung-Yu Ku, Christopher D. Liman, Justin E. Cochran, Michael F. Toney, Michael L. Chabinyc and Craig J. Hawker

      Article first published online: 26 APR 2011 | DOI: 10.1002/adma.201100028

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      A new method to aid large-area solution processing of organic small molecule semiconductors is reported. A thermally degradable poly(propylene carbonate) (PC) binder is added to a solution of soluble precursor to a tetrabenzoporphyrin to increase its viscosity, allowing for the use of large-area methods such as inkjet printing, slot coating, or blade coating. This method is used to make bulk heterojunction solar cells with a p-i-n type structure.

    5. Effect of Surface Roughness and Electrostatic Surface Potentials on Forces Between Dissimilar Surfaces in Aqueous Solution (pages 2294–2299)

      Markus Valtiner, Kai Kristiansen, George W. Greene and Jacob N. Israelachvili

      Article first published online: 25 JAN 2011 | DOI: 10.1002/adma.201003709

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      The first surface force measurements under electrochemical potential control between a metal and a ceramic surface across a liquid medium (water) are reported. Our experiments also investigate and reveal how increasing levels of surface roughness and dissimilarity between the potentials of the interacting surfaces influence the strength and range of electric double layer, van der Waals, hydration, and steric forces and how this contributes to deviations from DLVO theory at small distances within aqueous solution.

    6. Efficient and Color-Tunable Oxyfluoride Solid Solution Phosphors for Solid-State White Lighting (pages 2300–2305)

      Won Bin Im, Nathan George, Joshua Kurzman, Stuart Brinkley, Alexander Mikhailovsky, Jerry Hu, Bradley F. Chmelka, Steven P. DenBaars and Ram Seshadri

      Article first published online: 8 APR 2011 | DOI: 10.1002/adma.201003640

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      A solid solution strategy helps increase the efficiency of Ce3+ oxyfluoride phosphors for solid-state white lighting. The use of a phosphor-capping architecture provides additional light extraction. The accompanying image displays electroluminescence spectra from a 434-nm InGaN LED phosphor that has been capped with the oxyfluoride phosphor.

    7. Gate-Tunable Surface Processes on a Single-Nanowire Field-Effect Transistor (pages 2306–2312)

      Syed Mubeen and Martin Moskovits

      Article first published online: 25 FEB 2011 | DOI: 10.1002/adma.201004203

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      Surface chemical processes occurring on a Pd-nanoparticle-decorated tin oxide (SnO2) nanowire configured as a field-effect transistor (FET) can be strongly influenced by the gate potential if a high dielectric constant material is used as the gate oxide. Dramatic changes in channel currents are produced as a consequence when the device is exposed to hydrogen while operated in its depletion region, providing an example of gate-potential directed surface chemistry.

    8. Nanoscale Characterization of Tetrabenzoporphyrin and Fullerene-Based Solar Cells by Photoconductive Atomic Force Microscopy (pages 2313–2319)

      Michele Guide, Xuan-Dung Dang and Thuc-Quyen Nguyen

      Article first published online: 4 APR 2011 | DOI: 10.1002/adma.201003644

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      The subtle role of molecular designin determining organic photovoltaic performance performance is demonstrated with the aid of photoconductive atomic force microscopy. Each layer of OPV devices with a p/i/n architecture containing BP and PCBM or PCBNB is characterized using conducting and photoconducting AFM to gain insight as to why these devices perform differently in the bulk. The results illustrate how a slight change in the chemical structure of the layers can have a large impact in the film morphology, phase separation, and the device performance.

    9. Design and In Situ Characterization of Lipid Containers with Enhanced Drug Retention (pages 2320–2325)

      Benjamin Wong, Cecile Boyer, Christian Steinbeck, David Peters, Jason Schmidt, Ryan van Zanten, Bradley Chmelka and Joseph A. Zasadzinski

      Article first published online: 25 JAN 2011 | DOI: 10.1002/adma.201003578

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      Vesosome with distinct interior (green, orange) and exterior (blue) bilayer membranes. Drugs are encapsulated within the interior compartments and are protected from blood serum components by the exterior membrane. The outer membrane can be decorated with PEG lipids (red) to prevent aggregation in the blood as well as specific labels or targeting ligands.

  8. Frontispiece

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Modular Hydrogels: Tunable, High Modulus Hydrogels Driven by Ionic Coacervation (Adv. Mater. 20/2011) (page 2326)

      Jasmine N. Hunt, Kathleen E. Feldman, Nathaniel A. Lynd, Joanna Deek, Luis M. Campos, Jason M. Spruell, Blanca M. Hernandez, Edward J. Kramer and Craig J. Hawker

      Article first published online: 24 MAY 2011 | DOI: 10.1002/adma.201190075

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      Craig Hawker, Ed Kramer, and co-workers report on p. 2327 on a modular strategy for hydrogel formation based on the self-organization of welldefined ABA triblock co-polyelectrolytes through ionic interactions in water. The nature of the ionic domains, which constitute the physical crosslinks, provides for robust, yet highly tunable materials. These materials represent a diverse platform for hydrogel formation with enhanced mechanical properties and ease of synthesis while retaining a dynamic responsive nature.

  9. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Tunable, High Modulus Hydrogels Driven by Ionic Coacervation (pages 2327–2331)

      Jasmine N. Hunt, Kathleen E. Feldman, Nathaniel A. Lynd, Joanna Deek, Luis M. Campos, Jason M. Spruell, Blanca M. Hernandez, Edward J. Kramer and Craig J. Hawker

      Article first published online: 14 APR 2011 | DOI: 10.1002/adma.201004230

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      A modular strategy for hydrogel formation based on the self-organization of well-defined ABA triblock copolyelectrolytes through ionic interactions in water is reported. The nature of the ionic domains, which constitute the physical crosslinks, provides for robust, yet highly tunable materials. These materials represent a diverse platform for hydrogel formation with enhanced mechanical properties and ease of synthesis while retaining a dynamic responsive nature.

    2. Porous Carbon Produced in Air: Physicochemical Properties and Stem Cell Engineering (pages 2332–2338)

      Won Hyuk Suh, Jeung Ku Kang, Yoo-Hun Suh, Matthew Tirrell, Kenneth S. Suslick and Galen D. Stucky

      Article first published online: 21 APR 2011 | DOI: 10.1002/adma.201003606

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      A novel one-pot in situ templating method of synthesizing micro- and mesoporous carbon (spheres) in oxygenic conditions is reported. The mesoporous carbon has an extremely high surface area (over 1600 m2 g−1). We also introduce, for the first time, lactate as a source of carbon, which is relatively inexpensive and bio-friendly. To achieve this, aerosol-based methods are employed to create a mesoporous and nanostructured carbon-based material with the ultimate goal of influencing human stem cell biology.

    3. A New Femtosecond Laser-Based Tomography Technique for Multiphase Materials (pages 2339–2342)

      McLean P. Echlin, Naji S. Husseini, John A. Nees and Tresa M. Pollock

      Article first published online: 25 FEB 2011 | DOI: 10.1002/adma.201003600

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      A new tomography technique for image 3D nm-scale material features in mm3 volumes has been developed. The technique employs a femtosecond laser for layer-by-layer material removal at rates 4–5 orders of magnitude faster than comparable serial sectioning techniques. The technique can be applied to a wide range of multiphase materia ls and an example of its application for imaging of TiN particles inhomogeneously dispersed in a metallic matrix is given.

    4. Mechanism of Visible-Light Photocatalysis in Nitrogen-Doped TiO2 (pages 2343–2347)

      J. B. Varley, A. Janotti and C. G. Van de Walle

      Article first published online: 1 MAR 2011 | DOI: 10.1002/adma.201003603

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      The mechanism behind the visible-light absorption in N-doped titania is resolved through first-principles calculations of the formation energies and excitation energies of the relevant N-related defects in anatase and rutile TiO2. The results indicate that substitutional NO is the source of the visible-light absorption through the photo-excitation of a localized electron from the NO to the extended conduction-band states.

    5. Synthesis of Multifunctional Micrometer-Sized Particles with Magnetic, Amphiphilic, and Anisotropic Properties (pages 2348–2352)

      Siyoung Q. Choi, Se Gyu Jang, Andrew J. Pascall, Michael D. Dimitriou, Taegon Kang, Craig J. Hawker and Todd M. Squires

      Article first published online: 1 MAR 2011 | DOI: 10.1002/adma.201003604

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      Versatile methods are described for the fabrication of micrometer-scale particles with defined shape, ferro- or paramagnetic properties, and amphiphilic Janus surface chemistry. Examples of their utility include measuring the rheological properties of complex, two-dimensional fluid interfaces and reversible, directed self-assembly at fluid interfaces.

    6. Optoelectronic Gate Dielectrics for High Brightness and High-Efficiency Light-Emitting Transistors (pages 2353–2356)

      Ebinazar B. Namdas, Ben B.Y. Hsu, Jonathan D. Yuen, Ifor D. W. Samuel and Alan J. Heeger

      Article first published online: 26 APR 2011 | DOI: 10.1002/adma.201004102

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      The optoelectronic gate light-emitting field-effect transistor (OEG LEFET) containing alternate SiO2 and SiNx dielectric stacks allows enhanced light emission for a designed spectrum range and provides reliable strength for a wide operating voltage. The device can improve the emission efficiency by 4.5 times in comparison to a reference LEFET with a SiNx gate dielectric and can reach a brightness as high as 4500 cd/m2.

    7. Spontaneous Phase Separation Mediated Synthesis of 3D Mesoporous Carbon with Controllable Cage and Window Size (pages 2357–2361)

      Hyung Ik Lee, Galen D. Stucky, Jin Hoe Kim, Chanho Pak, Hyuk Chang and Ji Man Kim

      Article first published online: 15 APR 2011 | DOI: 10.1002/adma.201003599

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      Colloidal silica templated mesoporous carbons, which have not only systematically expanded large cage size (5–45 nm) but also controlled window size (5–25 nm), are successfully obtained via spontaneous phase separation of boron species from mixture of carbon precursor, boric acid, and colloidal silica during carbonization process. This novel synthesis offers a new chance to control the pore structure in materials obtained by nano-replication using rigid templates.

    8. Effects of Interfacial Redox in Mussel Adhesive Protein Films on Mica (pages 2362–2366)

      Jing Yu, Wei Wei, Eric Danner, Jacob N. Israelachvili and J. Herbert Waite

      Article first published online: 26 APR 2011 | DOI: 10.1002/adma.201003580

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      Formation of dehydrodopa in an adhesive mussel foot protein (mfp3) during autoxidation or periodate-mediated oxidation influences film thickness on mica in the surface forces apparatus (SFA). Dehydrodopa-dependent protein conformations in mussel plaque may enable different packing modes that are reversible.

  10. Research News

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Editorial
    6. Progress Report
    7. Frontispiece
    8. Communications
    9. Frontispiece
    10. Communications
    11. Research News
    1. Electrochemical Considerations for Determining Absolute Frontier Orbital Energy Levels of Conjugated Polymers for Solar Cell Applications (pages 2367–2371)

      Claudia M. Cardona, Wei Li, Angel E. Kaifer, David Stockdale and Guillermo C. Bazan

      Article first published online: 4 APR 2011 | DOI: 10.1002/adma.201004554

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      Electrochemical measurements are routinely used to determine the orbital energy levels of donor and acceptor materials under investigation for the fabrication of organic solar cells. There are, however, inconsistencies in the use of standard redox couples and the absolute potential of standard electrodes, which complicate comparison of materials properties and determination of structure/property relationships.

    2. Semiconductor Self-Assembled Quantum Dots: Present Status and Future Trends (pages 2372–2376)

      Pierre M. Petroff

      Article first published online: 24 MAY 2011 | DOI: 10.1002/adma.201100275

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      This paper presents the benefits of using self-assembled quantum dots into lattices by controlling their nucleation site positioning. The resulting narrower size dispersion translates into a narrower line width and higher density of the quantum dots ensemble. These characteristics could be useful to future developments in quantum dot devices used for quantum communication.

    3. Semimetal/Semiconductor Nanocomposites for Thermoelectrics (pages 2377–2383)

      Hong Lu, Peter G. Burke, Arthur C. Gossard, Gehong Zeng, Ashok T. Ramu, Je-Hyeong Bahk and John E. Bowers

      Article first published online: 15 APR 2011 | DOI: 10.1002/adma.201100449

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      Rare-earth doped III-V semiconductors are engineered for use in thermoelectric power generation applications. Codeposition by molecular beam epitaxy results in embedded semimetallic nanoparticles (as seen in the illustration) that enhance the thermoelectric properties of the III-V semiconductors. Segmented thermoelectric power generator modules are fabricated using 50 μm thick Er-containing nanocomposite films.

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