IEC 232 |
| Rama Venkatasubramanian, Center for Thermoelectrics Research, Center for Thermoelectrics Research, Research Triangle Institute, 3040 Cornwallis Road, Research Triangle Park, NC 27709 |
| Thin-film nano-structured materials offer the potential to dramatically enhance the performance of thermoelectrics, thereby offering new capabilities, ranging from CFC-free refrigeration to portable electric power sources, replacing batteries, to thermochemistry-on-a-chip. We demonstrated [1] a significant enhancement in thermoelectric figure-of-merit (ZT) at 300K - about 2.4 in 1nm/5nm p-type Bi2Te3/Sb2Te3 superlattice structures and recently, about 1.7 to 1.9 in 1nm/4nm n-type Bi2Te3/Bi2Te3-xSex superlattices, using the concept of phonon-blocking electron-transmitting superlattice structures. The phonon blocking arises from a complex localization-like behavior for phonons in nano-structured superlattices and the electron transmission is facilitated by optimal choice of band-offsets in these semiconductor heterostructures. More recently [2], Harman et. al has demonstrated a significant ZT enhancement in PbTe/PbTeSe quantum-dot superlattices, over PbTe-based materials, using similar reduction in thermal conductivity with nanostructures. The thin-film devices, resulting from microelectronic processing, allow high cooling power densities to be achieved for a variety of applications, with potential localized active-cooling power densities approaching 700 W/cm2. In addition to high-performance and power densities, these thin-film microdevices are also extremely fast acting, within ~10 to 20 microsec and about a factor of 23,000 faster than bulk thermoelectric devices. These results set the stage for a wide range of applications for the superlattice thin-film thermoelectric technology. Our technical progress in some of the near-term applications will be presented. [1] Nature, 413, 597-602 (2001); [2] Science, 297, 2297-2299 (2002) |
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Nanotechnology and the Environment
8:30 AM-11:55 AM, Thursday, March 27, 2003 Convention Center -- Room 392, Oral
Division of Industrial and Engineering Chemistry |