Seminar - Thermal Transport in Nanoporous Si: Anisotropy and Size effects by Dr. Baoling Huang
Date: 22 November 2012 (Thursday)
Time: 11:00 am – 12:00 pm
Venue: EF305, The Hong Kong Polytechnic University
High-performance thermoelectrics, which can directly convert thermal energy into electrical energy and vice versa without any moving parts, are urgently desirable for efficient thermal energy harvesting and solid-state thermal management. The applications of thermoelectric applications are limited by the low efficiency of current thermoelectrical materials, which are often made from heavy metals and are also expensive and toxic. While little progress in improving the performance of bulk thermoelectric materials has been made in recent decades, nanostructured thermoelectric materials have shown great potential in maximizing the thermoelectric efficiency. Through size effects and surface scattering, nanostructures provide the opportunities to engineer semiconductors that are poor thermoelectrics in their bulk form as high-performance thermoelectrical materials. Recent studies show that nanoporous Si is a very promising candidate for thermoelectrical applications. We have investigated thermal transport in nanoporous Si using nonequilibrium molecular dynamics simulations. It is found that the phononic patterns can prominently suppress the thermal transport in nanoporous Si while producing a highly tunable anisotropy in thermal conductivity. A two-part model has been developed to explain the thermal transport in phononically patterned Si. It further shows that stress inhomogeneity caused by the nanostructures can form thermal boundary resistances in a monolithic crystal. Due to this new scattering mechanism, compared with those low-dimensional structures, bulk semiconductors with phononic patterns may be a more promising candidate for thermoelectrical applications.
Dr. Baoling Huang received his B.S. and M.S. degrees in Engineering Thermophysics from Tsinghua University, Beijing in 1999 and 2001. He worked in industry from 2001 to 2004. In 2008, he received his Ph.D. degree in Mechanical Engineering from the University of Michigan, Ann Arbor. After graduation, he worked as a postdoctoral research fellow at the University of California, Berkeley and Lawrence Berkeley National Laboratory. He joined the Hong Kong University of Science and Technology in 2010. He has research experience on both theoretical modeling and experimental fabrications/measurements. His current research mainly focuses on developing the fundamental understanding of energy transport and conversion in novel thermoelectric materials.