LDRD Seminar Series: ‘Non-equilibrium Heat Dissipation at the Nanoscale’
Pierre Darancet
Assistant Scientist Pierre Darancet (NST) will discuss his Laboratory-Directed Research and Development (LDRD) sponsored work at the LDRD Seminar Series presentation Tuesday, Oct. 10, 2017.
“Non-equilibrium Heat Dissipation at the Nanoscale” begins at 12:30 p.m. in the Bldg. 203 Auditorium. All are welcome to attend.
Abstract
The need for improved thermal management of devices is ubiquitous in present day technologies, impacting fields as diverse as the miniaturization of electronic components, the durability of new-generation solar cells, and the efficiency of thermoelectrics and thermophotovoltaics. As the United States wastes more energy than it consumes principally in the form of waste heat, the U.S. Department of Energy (DOE) has pointed out the urgency of “extending the range of existing [waste heat recovering] technologies to enhance their economic feasibility and recovery.” In this context, the synthesis of nanoscale materials and hierarchical architectures with properties beyond the reach of classical and continuum descriptions offer challenges and opportunities. In particular, novel degrees of freedom in controlling thermal generation, conduction, and radiation emerge as the timescales associated with such phenomena approach the ones of electron-, plasmon- and phonon-thermalization and as devices operate far from thermodynamic equilibrium.
At Argonne, we are collaborating with scientists at the Materials Science Division, Advanced Photon Source, and at the Center for Nanoscale Materials, in an effort to characterize, model, understand and control the microscopic phenomena underlying heat science at short time- and length-scales. Specifically, I will show how our work has led to the observation and explanation of the breakdown of the classical lattice temperature model for timescales up to hundreds of picoseconds in cubic semiconductors and lead-halide perovskites. In particular, I will show how electron-phonon and phonon-phonon interactions in such materials under irradiation lead to a vibrational-mode-specific temperature, and discuss their implications in developing better thermal management models for nanoscale devices, as well as better characterization of materials properties. Moreover, this presentation will discuss the impact of nanoscale interfaces on heat conduction, motivated by the recent advent of time-resolved coherent microscopy and inelastic spectroscopy of the lattice dynamics at timescales comparable to the ones of electron-phonon interactions and phonon-propagation. Finally, our work shows how advanced synthesis techniques such Atomic Layer Deposition can be leveraged to design the thermal radiation of materials beyond the black-body paradigm; leading to materials with better thermophotovoltaic efficiency.
Biography
Since 2014, Pierre Darancet has been an assistant scientist at the Center for Nanoscale Materials, a DOE Nanoscale Research Center for interdisciplinary research at the nanoscale. He is also a Fellow of the Northwestern University — Argonne Institute of Science and Engineering. Darancet works on understanding charge and energy transport in nanostructures and across interfaces. In particular, he develops and uses first-principles methods for predicting the electrical, thermal, and optical properties of nanoscale materials. His current research foci are in the fields of current-induced lattice dynamics and exciton dynamics. Since 2015, he has been the principal investigator of an LDRD Prime grant on “Managing Emission and Thermal Absorption.”
Prior to joining Argonne, Darancet obtained his Ph.D. in 2008 in physics from the Université Joseph Fourier, Grenoble, France under the supervision of Didier Mayou and Valerio Olevano, working on developing numerical methods for modeling quantum transport in nanostructures. From 2008 to 2012, as a postdoctoral fellow at the Molecular Foundry, Lawrence Berkeley National Laboratory under the supervision of Jeffrey B. Neaton, he modeled the optical and transport properties of organic/metal interfaces for single-molecule electronics. From 2012 to 2014, as a postdoctoral research scientist at Columbia University, he worked in understanding the electronic structure of strongly-correlated two-dimensional materials under the supervision of Chris Marianetti and Andrew Millis.
