DURHAM – Alternative and sustainable sources of energy are crucial to the future health, safety and welfare of society. Researchers in Duke University’s Thomas Lord Department of Mechanical Engineering & Materials Science are meeting the challenge of finding and deploying novel energy sources and by developing materials that have the potential to power our future.
They are uncovering the mysteries of harnessing and transmitting heat, light and electricity by investigating materials’ atomic structures and the behaviors of subatomic particles and using those insights to design materials with specific properties for a host of applications. Their work is advancing development of solar energy, longer-lasting rechargeable batteries, capture of waste heat from power plants and automobile exhaust, new semiconductors and even cooling textiles for personal comfort.
Read more about what Duke MEMS faculty are doing to fuel a more sustainable future:
Making Energy Materials More Effective and Cost-Efficient by Discovering New Properties and How They Relate to Underlying Atomic Structures
Simon Family Professor of Mechanical Engineering & Materials Science
David Mitzi develops new, sustainable materials for energy and optoelectronic applications including solar cells and water-splitting, as well as spintronic (using flow of an electrons’ spin rather than charge) and light-emitting devices. His group investigates two materials classes for use in such devices–halide-based perovskites and complex chalcogenide semiconductors–which both hold the potential for low-cost next-generation devices. Within each of these areas, Mitzi’s group works to design novel materials, as well as to understand the fundamental chemical, structural, optical and electronic properties underlying the semiconductors. They also develop film/crystal growth techniques and build device structures around the new materials to achieve outstanding device performance.
Mitzi is one of 16 researchers, along with Duke colleagues Volker Blum and Adrienne Stiff-Roberts, collaborating in the Center for Hybrid Organic-Inorganic Semiconductors (HOIS) for Energy funded by the U.S. Department of Energy. He and Stiff-Roberts co-lead the center’s focus area dedicated to design and synthesis of perovskites, a specific class of HOIS, which hold great promise for light-, charge- and spin-based applications and new types of solar cells because of their crystalline structure.
Mitzi and Blum are also collaborating on a National Science Foundation (NSF) “Designing Materials to Revolutionize and Engineer our Future” (DMREF) grant with teams of researchers at the University of North Carolina and North Carolina State University. They are working to identify new hybrid organic-inorganic perovskites (HOIPs) and accelerate development of this materials space among the wider community of researchers through the curated open HybriD3 database of experimental and computational materials data.
Mitzi is leading a new NSF-funded project in collaboration with researchers at the University of Colorado to extend beyond current approaches in HOIP research, which focus on the ordered patterns of their crystalline structures. Instead, they will investigate and demonstrate how controllable disorder—for example, glass-like structure—can be introduced to expand the range of properties and applications for the HOIP family.
Prior to joining the faculty at Duke in 2014, Mitzi spent 23 years at IBM’s T.J. Watson Research Center, where he focused on the search for and application of new electronic materials, including organic-inorganic perovskites and inorganic materials for photovoltaic, LED, transistor and memory applications.
He is a Fellow of the Materials Research Society (MRS) and has authored or coauthored more than 200 papers and book chapters and holds more than 40 patents. Clarivate Analytics designated him among the world’s most highly cited researchers from 2018-2020. In 2020, his peers in the American Chemical Society recognized his work with the National Award in the Chemistry of Materials.
“We enjoy exploring the connection between crystal structure and physical/chemical properties and use this knowledge to design and create new highly functional materials for energy and electronic applications.”
Discovering Atomic Properties of Materials to Address Specific Energy Needs
Associate Professor of Mechanical Engineering & Materials Science
Focusing on problems at the intersection of materials science, physics and chemistry, Olivier Delaire and his group investigate atomic-level processes underlying energy transfers and thermodynamics in energy materials. His fundamental research points the way to developing future materials with improved properties to address energy needs.
For example, his extensive studies have probed atomic vibrations, known as phonons, within crystals and endeavored to understand microscopic origins of heat and ion transport in a wide range of energy materials.
His recent research has revealed the peculiar atomic dynamics that provide desirable properties for solar energy and heat energy applications to an exciting class of materials called halide perovskites. He found that these materials exhibit an excellent flexibility and tolerance to defects by the way their atomic lattice twists and turns in a hinge-like fashion. This molecular hinge allows a sort of “floppiness” that keeps electrons knocked free by sunlight available for use and makes it difficult for heat to travel through the structure. These results should help materials scientists tailor their chemical recipes for a wide range of applications in an environmentally friendly way.
In other recent work he and collaborators at Michigan State University gained insight into two magnesium-based materials that can outperform traditional compositions of thermoelectric generators, which turn heat into electricity or vice versa. These materials would also be more environmentally friendly and less costly to manufacture. These findings may indicate new pathways for improving thermoelectric generators used in power plants, automobiles, refrigeration and even future space missions to Mars and beyond.
The new understanding of atomic dynamics from his research is also key in his group’s ongoing investigations of ionic diffusion for safer and longer-lasting rechargeable batteries. By understanding how crystal lattices bend and vibrate, engineers can better design so-called superionic conductors, which allow fast diffusion of ions for next-generation solid-state batteries with no flammable components.
Delaire recently won an NSF-funded DMREF grant to lead a team in developing an integrated computational and experimental framework for gaining insight into the atomic-scale mechanisms controlling superionic behavior with collaborators at North Carolina State, Harvard and Michigan State Universities.
His research group uses advanced experimental and computational approaches, including neutron and X-ray scattering studies at the U.S. Department of Energy’s Oak Ridge and Argonne National Laboratories and supercomputer simulations at the National Energy Research Scientific Computing Center. Prior to joining Duke, Delaire was a staff scientist at the Oak Ridge National Laboratory.
“We explore how the atomic-scale behavior of materials can enable big changes in our energy future. Duke is a perfect place to conduct exciting basic research with high-tech payoffs. We benefit from tremendous collaborations across Duke’s Pratt School of Engineering and its Trinity College of Arts & Sciences, the nearby Research Triangle Park and talented students passionate about building a more sustainable world.”
Developing New Textiles to Manage Light and Heat for Energy Applications
Assistant Professor of Mechanical Engineering & Materials Science
Po-Chun Hsu’s research group develops innovative textile materials for light and heat management. Working at the nanoscale, he tailors these materials to either transmit, block or absorb thermal radiation to address specific engineering challenges.
For example, he has addressed the challenge of lowering energy consumption and the cost of heating and cooling buildings by designing cooling textiles to lower wearers’ thermal radiation so that they can tolerate higher air conditioning settings.
Attacking the problem from another angle, he has developed a dual-mode heating and cooling device for building climate control that, if widely deployed in the U.S., could cut HVAC energy use by nearly 20%. The invention uses a combination of mechanics and materials science to either harness or expel certain wavelengths of light, depending on the need.
Hsu joined Duke MEMS in 2019 with a passion for finding creative solutions for sustainable energy and to combat the effects of climate change. His work is highly interdisciplinary and informed by knowledge in mechanical engineering and materials science, thermodynamics, chemistry and photonics.
Currently Hsu and his group have several projects in the pipeline under the theme of light- and heat-managing materials. For instance, they are developing a dual-mode wearable device that only needs one coin cell battery to provide week-long personalized thermal comfort whether the temperature is cold or hot.
“The pressing need to reduce our carbon footprint is an important driving force, but I find that tackling a lot of ‘what if’ questions from the aspect of fundamental science is truly the fun part.”
Read more about how Duke researchers are using computational and artificial intelligence methods to develop new energy materials.
Also, meet additional Duke faculty working on new energy systems and materials.
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