MSE Colloquium Series
Winter Quarter 2014
Fridays at 3:15 to 4:45 in McCullough Building Room 115
Prof. Zhenan Bao
Skin-Inspired Electronics From Organic and Carbon Nanomaterials
Abstract: Organic and carbon nano materials are attractive for low cost electronic units for electronic skin as well as medicinal, food storage, and environmental monitoring applications. The ability to couple the sensory electrical output with on-chip signal processing can overcome the need for bulky, expensive equipment typically required for most optical detection methods. In this talk, I will present recent progress in materials design to enhance charge transport properties and to enable high performance large area solution coated flexible and stretchable transistors and sensors. Finally, the application of these materials and devices for skin-inspired sensors, electronics and battery devices will be presented.
Bio: Zhenan Bao is a Professor of Chemical Engineering at Stanford University, and by courtesy a Professor of Chemistry, Material Science and Engineering. Prior to joining Stanford in 2004, she was a Distinguished Member of Technical Staff in Bell Labs, Lucent Technologies from 1995-2004. She has over 300 refereed publications and 39 US patents. She has a H-index of 77 and has been cited more than 22,000 times. Bao served as a Board Member for the National Academy Board on Chemical Sciences and Technology and Board of Directors for the Materials Research Society (MRS). She serves on the international advisory board for Nature Asia Materials, Advanced Materials, Advanced Functional Materials, Advanced Energy Materials, ACS Nano, Chemistry of Materials, Nanoscale, Chemical Communication, Organic Electronics, Materials Horizon and Materials Today. She was elected a SPIE Fellow in 2008, an ACS Polymer Materials Science and Engineering Fellow in 2011, ACS Fellow in 2011 and AAAS Fellow in 2012. She is a recipient of the ACS Polymer Division Carl S. Marvel Creative Polymer Chemistry Award 2013, ACS Author Cope Scholar Award 2011, Royal Society of Chemistry Beilby Medal and Prize 2009, IUPAC Creativity in Applied Polymer Science Prize 2008, American Chemical Society Team Innovation Award 2001, R&D 100 Award 2001. She was selected by MIT Technology Review magazine in 2003 as one of the top 100 young innovators. She is among the world’s top 100 materials scientists who achieved the highest citation impact scores for their papers published since January 2000 by Thomson Reuters. She is a co-founder and board of director of C3 Nano, a silicon valley start-up to commercialize transparent electrodes and stretchable electronics.
Prof. James Hone
Putting things on top of other things: Fabrication and applications
Prof. Michael J. Demkowicz
Designing metallic glasses with tailored radiation response using reduced order mesoscale models
Abstract: Computational materials science brings a physics-based materials design capability within reach. However, materials design for radiation response is challenging because it deals with inherently collective mechanisms operating at multiple time and length scales. I will present a design strategy built on reduced order mesoscale models, which afford simplified descriptions of the essential physics of complex, collective materials phenomena. As an illustration, I will explain how metallic glasses may be altered to achieve tailored radiation response.
Bio: Michael J. Demkowicz did his undergraduate studies at the University of Texas at Austin, receiving three Bachelor’s degrees in 2000: BS Physics, BS Aerospace Engineering, and BA Plan II Honors (a core-curriculum liberal arts program). He did his graduate work with A. S. Argon at MIT, receiving his MS and PhD in mechanical engineering in 2004 and 2005, respectively. Afterwards, he spent three years at Los Alamos National Laboratory, first as a postdoc, then as a Director’s Fellow, and finally as a technical staff member. In 2008, Demkowicz joined the faculty at MIT’s Department of Materials Science and Engineering, receiving the John C. Chipman career development char. In 2012, he received an NSF CAREER award and the TMS Early Career Faculty Fellow award. Demkowicz works at the intersection of fundamental materials physics and computational design of structural materials.
Prof. Xiaoyang Zhu
Solar energy conversion beyond the limit
Abstract: The absorption of one photon by a semiconductor material usually creates one electron-hole pair, but this general rule breaks down in a few organic semiconductors, such as pentacene and tetracene, where one photon absorption may result in two electron-hole pairs in a process called singlet exciton. Recent measurements in our group by time-resolved two-photon photoemission (TR-2PPE) spectroscopy in crystalline pentacene and tetracene provided the first spectroscopic signatures in singlet fission of a critical intermediate known as the multiexciton state. More importantly, population of the multiexciton state is found to rise concurrently with that of the singlet state on the ultrafast time scale upon photo excitation. This observation provides an experimental foundation for a quantum coherent mechanism in which the electronic coupling creates a quantum superposition of the singlet and the multiexciton state immediately following optical excitation. We demonstrate the feasibility of harvesting the multiexciton state for multiple charge carriers or the triplets. We outline a set of design principles for molecular materials with high singlet fission yield and for the implementation of singlet fission for solar energy conversion beyond the Shockley-Queisser limit.
Bio: Xiaoyang Zhu is a Professor of Chemistry at Columbia University. He received a BS degree from Fudan University in 1984 and a PhD from the University of Texas at Austin in 1989. After postdoctoral research with J. Mike White at UT-Austin and Gerhard Ertl at the Fritz-Haber-Institute, he joined the faculty at Southern Illinois University as an Assistant Professor in 1993. In 1997, he moved to the University of Minnesota as an Associate Professor, later a Full Professor and Merck endowed Professor. In 2009, he returned to Austin as the Vauquelin Regents professor of Chemistry. On January 1st, 2013, Zhu moved to Columbia University. His honors include a Dreyfus New Faculty Award, a Cottrell Scholar Award, a Friedrich Wilhelm Bessel Award, and Fellow of the American Physical Society. Among his professional activities, he serves on the editorial/advisory boards of Progress in Surface Science, Accounts of Chemical Research, & Chemical Physics.
Prof. R.J. Dwayne Miller
Mapping Atomic Motions with Ultrabright Electron and X-ray Sources: The Chemists’ Gedanken Experiment Enters the Lab Frame
Prof. Matthias Wuttig
Phase Change Materials: From Optical Data Storage to Novel Electronic Memories
Abstract: Phase change media are among the most promising materials in information technology. These materials can be very rapidly switched between the amorphous and the crystalline state, indicative for peculiar crystallization behaviour. They are already employed in rewriteable optical data storage, where the pronounced difference of optical properties between the amorphous and crystalline state is used. This unconventional class of materials is also the basis of a storage concept to replace flash memory. This talk will discuss the unique material properties, which characterize phase change materials. In particular, it will be shown that the crystalline state of phase change materials is characterized by the occurrence of resonant bonding, a particular flavour of covalent bonding. This insight is employed to predict systematic property trends and to develop non-volatile memories with DRAM-like switching speeds potentially paving the road towards a universal memory. Phase change materials do not only provide exciting opportunities for applications including ‘greener’ storage devices, but also form a unique quantum state of matter as will be demonstrated by transport measurements.
Bio: Since 1997 Full Professor of Physics at the RWTH Aachen University, Germany; Speaker of the strategy board of RWTH Aachen (since 2009); Dean of the Faculty of Science, Mathematics and Computer Sciences (2006-2008); Speaker of the collaborative research center (SFB 917) Nanoswitches; Head of the Research Group: Physics of novel Materials, Research mission: prepare and characterize novel materials with unique optical and electronic properties. Conduct research in the fields of: a) chalcogenide based semiconductors (phase change materials), b) organic materials for opto-electronic applications, c) optical functional coatings. Visiting professor at CRMC2 - CNRS Marseille (4/1995), AT&T Bell Laboratories, Murray Hill (1995-1997), Hangzhou University (8/1998), Kenyatta University (1999), IBM Research Center Almaden (Spring 2006), Data Storage Institute Singapore (10/2007), Shanghai Institute of Microsystems and Information, Chinese Academy of Sciences (8/2009), Stanford University (Spring 2010), Lawrence Berkeley National Laboratory (Summer 2010). Several national and international awards, including ERC Advanced Grant (2013).
Prof. David C. Martin
Defect-Mediated Charge Transport and Plastic Deformation in Conjugated Polymers and Organic Molecular Crystals
Abstract: Our group has been investigating the fundamental relationship between structural defects and the macroscopic charge transport and mechanical plasticity of conjugated polymers and organic molecular crystals. These materials are of considerable current interest for a variety of applications including photovoltaics, thin-film transistors, and for interfacing electronic biomedical devices with living tissue. The defects of interest include vacancies, dislocations, and grain boundaries. The molecular nature of these solids introduces new constraints on the structure, energetics, and mobilities of these defects. For example, vacancies in crystalline molecular solids are almost always expected to have substantial contributions to the entropic component of the energy of the defect, whereas for inorganic crystals this can usually be neglected. We have examined the local structure of these materials in considerable detail by using low dose high-resolution transmission electron microscopy and electron diffraction. We have studied a variety of materials systems including single crystals and of bicrystals polydiacetylenes, polycrystalline thin films of pentacene and functionalized pentacene, and functionalized polythiophenes. Examples from past studies, as well as recent efforts focused on the design and characterization of electronically and ionically conductive materials for biomedical devices will be presented.
Prof. Nathan S. Lewis
Sunlight-Driven Hydrogen Formation by Membrane-Supported Photoelectrochemical Water Splitting
Abstract: We are developing an artificial photosynthetic system that will only utilize sunlight and water as the inputs and will produce hydrogen and oxygen as the outputs. We are taking a modular, parallel development approach in which the three distinct primary components-the photoanode, the photocathode, and the product-separating but ion-conducting membrane-are fabricated and optimized separately before assembly into a complete water-splitting system. The design principles incorporate two separate, photosensitive semiconductor/liquid junctions that will collectively generate the 1.7-1.9 V at open circuit necessary to support both the oxidation of H2O (or OH-) and the reduction of H+ (or H2O). The photoanode and photocathode will consist of rod-like semiconductor components, with attached heterogeneous multi-electron transfer catalysts, which are needed to drive the oxidation or reduction reactions at low overpotential. The high aspect-ratio semiconductor rod electrode architecture allows for the use of low cost, earth abundant materials without sacrificing energy conversion efficiency due to the orthogonalization of light absorption and charge-carrier collection. Additionally, the high surface-area design of the rod-based semiconductor array electrode inherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent density at the solid/liquid junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. A flexible composite polymer film will allow for electron and ion conduction between the photoanode and photocathode while simultaneously preventing mixing of the gaseous products. Separate polymeric materials will be used to make electrical contact between the anode and cathode, and also to provide structural support. Interspersed patches of an ion conducting polymer will maintain charge balance between the two half-cells. The modularity of the system design approach allows each piece to be independently modified, tested, and improved, as future advances in semiconductor, polymeric, and catalytic materials are made. Hence, this work will demonstrate a feasible and functional prototype and blueprint for an artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, manufacturably scalable, and readily upgradeable.
Bio: Dr. Nathan S. Lewis, the George L. Argyros Professor of Chemistry, has been on the faculty at the California Institute of Technology since 1988 and has served as Professor since 1991. He is the Scientific Director of the Joint Center for Artificial Photosynthesis, the Energy Innovation Hub in Fuels from Sunlight, and has also served as the Principal Investigator of the Beckman Institute Molecular Materials Resource Center at Caltech since 1992. From 1981 to 1986, he was on the faculty at Stanford, as an assistant professor from 1981 to 1985 and as a tenured Associate Professor from 1986 to 1988. Dr. Lewis received his Ph.D. in Chemistry from the Massachusetts Institute of Technology.
Prof. Joachim Maier
The significance of defect chemistry for lithium-based batteries
Abstract: Professionally dealing with solids requires the understanding of the charge carrier chemistry (point-defect chemistry). While defect chemical considerations are state-of-the-art in solid state ionics at high temperatures, this is not the case for room-temperature situations as they are met in Li-based batteries. It is shown how information on storage thermodynamics and rkinetics can be extracted from point defect considerations for various storage modes. The relevance will be shown using specific examples. Of particular interest for the room temperature defect situation are interaction reactions between Li-ion and electronic carriers, frozen-in charge carrier concentrations, defect thermodynamics in nano-sized and amorphous materials, storage in extremely confined systems (nanodots) as well as heterogeneous storage in composite systems.
Bio: Joachim Maier is Director at the Max Planck Institute for Solid State Research in Stuttgart (Germany) and heads the department of Physical Chemistry. J. Maier studied chemistry in Saarbruecken, obtained his Masters and PhD in Physical Chemistry there. He received his professorial degree (Habilitation) at the University of Tuebingen. From 1988 to 1991 he was responsible for the activities on functional ceramics at the MPI for Metals Research in Stuttgart, and from 1988 to 1996 (as a Foreign Faculty Member) he taught defect chemistry at the Massachusetts Institute of Technology. In 1991, after having declined other prestigious offers (Materials Science M.I.T., Institute of New Materials Saarbruecken, Physical Chemistry Marburg), he was appointed Scientific Member of the Max Planck Society, Director at the MPI for Solid State Research and Honorary Professor at the University of Stuttgart. J. Maier has authored/co-authored more than 700 scientific papers in refereed journals and 26 patents in the field of physical chemistry and electrochemistry of the solid state. His major research field is ion transport in solids. He is also author or editor of several books and has organized various international conferences on these subjects. Under this headline, research is devoted to electrochemistry, equilibrium and non-equilibrium thermodynamics of charge carriers and chemical kinetics of solid state processes (Solid State Ionics, Defect Chemistry, Nanoionics). He was awarded both the PhD Award Fellowship and the Lecturer Award Fellowship of the German Chemical Industry. He received the Carl-Duisberg-Award of the German Chemical Society, the E.-Martin-Prize of the University of Saarbruecken and the Norman Hackerman Award of the Electrochemical Society. He is co-recipient of the 2002, 2004 and 2005 Edward C. Henry Awards and of the 2005 Ross Coffin Purdy Award of The American Ceramic Society. He is a member of the German Academy of Sciences and Literature (Mainz), a member of the German Academy of Science and Engineering (acatech), a member of the Academia Europaea, Fellow of the Royal Society of Chemistry and an Honorary Member of the National Institute of Chemistry in Ljubljana. He was Visiting Professor at the M.I.T. and TU Graz; he was appointed Herbert Johnson-Award lecturer (Cornell University), Richard-Willstaetter lecturer of the GDCh (Hebrew University of Jerusalem) and Seidman lecturer (Technion) and Lecture-Professor (Institute of Chemistry, Chinese Academy of Science Beijing). He also gave the Wilhelm-Jost lecture series of the Deutsche Bunsen-Gesellschaft (2007). He was Vice President (2011-2013) and is President (2013-2015) of the International Society for Solid State Ionics. Joachim Maier is Editor-in-Chief of Solid State Ionics and on the Board of various scientific journals (Adv. Funct. Mater., Chem. Mater., J. Electroceramics, J. Solid State Electrochem., Z. Phys. Chem., Materials Science Foundations, Trends in Physical Chemistry). He served as officer on councils of various societies and organizations (ISE, ISSI, DBG, GDCh, MPG, BDI, IAEA, FZ Juelich among others); he was chairman of the Solid State Chemistry Division of GDCh, chairman of the New Topics Committee (International Society of Electrochemistry) and Titular Member of the IUPAC Physical and Biophysical Chemistry Division Committee.