Description:

The Department of Materials Science and Engineering welcomes you to its 2015 Winter Colloquium Series.

Location: Tech L361, 4:00pm

Supratik Guha
IBM Research

“Earth abundant vacuum deposited kesterite thin film solar cells”

For solar cells to be cheap and available in quantities to meet demands of ~ 50 GWp/year (for photovoltaics to make a significant dent in worldwide electricity production), it is desirable that they be made of materials that are earth abundant, stable, preferably non-toxic, and viable in polycrystalline form (to obviate the need for expensive single crystal substrates). Among the new materials being investigated, the kesterite compound copper zinc tin sulfide (CZTS) is an attractive solar cell absorber material that meets these criteria, provided the efficiencies of the cells can be increased to beyond its current value of ~9%. If one is willing to add some Se (CZTSSe) and tolerate some non-toxicity, efficiencies of ~ 12-12.5% may be achieved. These numbers however need to be >~15% for for pre-manufacturing activities in CZTS or CZTSSe to begin, and likely >~18% for them to be successful candidates for manufactured products in the future. Using examples from vacuum deposited CZTS, I will describe some of the materials issues that limits current electrical performance, the most significant among them being an open circuit voltage that is quite low. I will describe the role that microstructure and phase stability in this material plays, and the effect that Na addition has on grain growth and photovoltaic properties. In order to identify the role of extended defects and grain boundaries on performance, we have also begun a study of epitaxial CZTS grown on near lattice matched silicon substrates by molecular beam epitaxy, and these results will be discussed. Finally, I will show some of our early results in the successful demonstration of monolithic tandem kesterite-perovskite solar cells.

Biography:
Supratik Guha is presently the Director of Physical Sciences at IBM Research, where he has been since 1995. During his time at IBM he initiated and led the high dielectric constant (high-k) oxide materials research at IBM and was responsible for some of the key materials and processes that led to IBM's high-k metal gate CMOS technology. His current research interests are in new semiconductors and oxides for logic, and energy conversion applications. Supratik received his Ph.D. in Materials Science from the University of Southern California in 1991, and his B. Tech from the Indian Institute of Technology, Kharagpur (India) in 1985. He is also currently an adjunct professor of materials science at Columbia University. He is a fellow of the American Physical Society and the Materials Research Society.

Description:

The Department of Materials Science and Engineering welcomes you to its 2015 Winter Colloquium Series.

Location: Tech L361, 4:00pm

Bringing Physics into the Fold: Origami-Inspired Mechanical Meta-materials

Tessellated patterns, realistic animals, and curved polygonal shapes are all examples of the beautiful and amazing sculptures that can now be made using Origami, the art of paper folding. This art form has experienced tremendous growth with the advent of mathematical techniques that allow the basic structure of any new sculpture to be plotted out before any folding occurs, and laser cutter technologies that have made it easier to create folds in a variety of materials. In addition to their static properties, Origami sculptures can be designed to have a wide variety of mechanical properties making them responsive and tunable. In this talk I will describe our efforts to bring together artists, materials scientists, engineers, mathematicians, and yes, physicists to make meta-materials base on origami principles. Our teams are interested in making structures with a broad range properties including, tunable mechanical stiffness, mechanical cloaking capabilities, and topological constraints that can be utilized to design switches. The materials we work with range from paper models, to thermally responsive gel sheets, and even graphene. Collectively, we strive to design material platforms that can be used as building blocks for the nano and micro scale mechanical devices of the future.

BIO:
Professor Itai Cohen is obsessed with motion on various length scales. At Cornell, his research has focused on investigating the behavior of microscopic and nanoscopic particles suspended in a fluid, exploring the mechanics of materials ranging from biological tissues to origami inspired metamaterials, and discovering the mechanisms used by insects during flapping flight. Understanding the out-of-equilibrium behavior of these systems and their non-linear response to applied forces remains one of the biggest challenges in Physics.

Description:

The Department of Materials Science and Engineering welcomes you to its 2015 Winter Colloquium Series.

Dr. Carol Hirschmugl, Professor
University of Wisconsin Milwaukee

Tuesday, February 3, 2015
4:00pm, Tech L361

“Simultaneous 3D Detection of Organics with Infrared Spectromicrotomography ”

The holy grail of chemical imaging is to provide spatially and temporally resolved information about heterogeneous samples on relevant scales. Synchrotron-based Fourier Transform infrared imaging1 combines rapid, non-destructive chemical detection with morphology at the micrometer scale, to provide value added results to standard analytical methods. Hyperspectral cubes of (x,y, z, Abs ((lamdba please use symbol font))) are obtained employing spectromicrotomography2, a label free approach, it inherently evaluates a broad array of wide organic materials, with minimal sample preparation and modification. Examples presented here (polymer composites, single cells and colonies of cells) demonstrate the broad applicability of this approach to detect complex chemical information of intact samples.

Biography:
Dr. Carol Hirschmugl received her B.S. in Physics from State University of New York at StonyBrook in 1987 and her Applied Physics Ph.D. from Yale University in 1994. She then received an Alexander von Humboldt grant to do research at Fritz Haber Institut, Berlin, from 1994-1996. In 1996 she was awarded the University of Califoria's Presidential Postdoctoral Fellowship to work at Lawrence Berkeley National Laboratory. Since 1997, Hirschmugl has been at the University of Wisconsin-Milwaukee, where she is a professor in the Physics Department and the Director of the Laboratory for Dynamics and Structure at Surfaces.

Description:

The Department of Materials Science and Engineering welcomes you to its 2015 Winter Colloquium Series.

Location: Tech L361, 4:00pm

More information to come soon!

Description:

The Department of Materials Science and Engineering welcomes you to its 2015 Winter Colloquium Series.

The 6th Annual Morris Fine Lecture

Tuesday, February 24, 2015
4:00pm, Tech L361

Reception to follow for all attendees:
5:00pm - 6:00pm, Willens Wing Atrium (Tech)

Christopher A. Schuh, Professor
Head of the Department of Materials Science and Engineering,
Massachusetts Institute of Technology

“Grain Boundary Alloying in Nanocrystalline Metals, from Theory to Practice”

When the grain size of a metal is refined to a scale on the order of just a few nanometers, its strength, hardness, wear resistance, and other properties improve in dramatic ways. There is therefore significant interest in designing and deploying such nanocrystalline alloys for structural applications. However, refining the grain structure is a struggle against equilibrium, and nanocrystalline materials are usually quite unstable; the grains grow given time even at room temperature, and the associated property benefits decline over time in service. The future of nanocrystalline materials therefore lies in stabilizing their structure, which in turn expands their processability and opens the door to application-relevant service lifetimes. This talk will review the concept of grain boundary alloying as a method to lower the energy of grain boundaries, which can bring a nanocrystalline structure closer to equilibrium and stabilize it for engineering use. The pathways from theory, to proof-of-concept laboratory demonstration, to scale-up and commercialization of such alloys will be highlighted. The current applications and future prospects of stable nanocrystalline metals will be described, including as substitute materials to reduce cost and cost volatility, as greener alternatives to legacy technologies, and as next-generation structural materials with large performance increments over incumbent metals.

Biography:
Christopher A. Schuh is the Department Head and the Danae and Vasilis Salapatas Professor of Metallurgy in the Department of Materials Science and Engineering at MIT. He joined MIT in 2002, having received a B.S. degree at the University of Illinois at Urbana-Champaign, and a Ph.D. at Northwestern University, both in the field of Materials Science and Engineering. Prof. Schuh also held the Ernest O. Lawrence postdoctoral fellowship at Lawrence Livermore National Laboratory. Prof. Schuh’s research is focused on structural metallurgy, and seeks to control disorder in metallic microstructures for the purpose of optimizing mechanical properties; much of his work is on the design and control of grain boundary structure and chemistry. Prof. Schuh has published more than 200 papers and dozens of patents, and received a variety of awards acknowledging his research accomplishments. He co-founded Xtalic Corporation, a technology spin-out company that has commercialized a new process for dynamically controlling the nanostructure in electrodeposited metals, with applications ranging from automotive and machine components to electronics. Prof. Schuh has been named a MacVicar Fellow of MIT, recognizing his contributions to engineering education, and was recently elected a Fellow of The Minerals, Metals, and Materials Society.