| AVS 58th Annual International Symposium and Exhibition | |
| Energy Frontiers Focus Topic | Tuesday Sessions |
| Session EN+NS-TuA |
| Session: | Nanostructured Materials for Thermophotovoltaics, Thermoelectrics & Plasmonics |
| Presenter: | Andrew Lohn, University of California Santa Cruz |
| Authors: | A.J. Lohn, University of California Santa Cruz E. Coleman, Structured Materials Industries, Inc. G.S. Tompa, Structured Materials Industries, Inc. N.P. Kobayashi, University of California Santa Cruz |
| Correspondent: | Click to Email |
Current energy production mechanisms for electrical power and transportation are plagued by inefficiencies which results in most of the energy source being lost as heat. In most cases that heat is found in the form of low-grade heat with temperatures below approximately 200 degrees C. Unfortunately, typical methods such as the Rankine cycle for converting heat to electricity suffer from poor efficiency for low-grade heat. Direct thermoelectric conversion is currently struggling to match the efficiency of the Rankine cycle at high temperatures but offers advantages in terms of reduced maintenance and form-factor which enable energy scavenging in places such as the exhaust line of a vehicle where larger systems could not be implemented.
Dominated by recent progress in nanostructured materials, the unitless thermoelectric figure of merit ZT has been increased to well beyond 1 such that efficiencies are reaching a range which makes them cost effective. Typically thermoelectric materials include elements such as lead or tellurium which are toxic and rare therefore alternative materials are being sought. Recent progress in silicon nanowire thermoelectric has shown a reduction in thermal conductivity, and therefore an increase in ZT of two orders of magnitude, making them viable candidates in the thermoelectric marketplace. Decreased cost and toxicity of silicon as compared to conventional thermoelectric materials make it an attractive candidate but to date nearly all studies on thermoelectricity of nanowires have focused on nanowires in isolation. Our platform based on interconnected 3-dimensional nanowire networks grown directly on metallic substrates provides large area thermoelectric modules capable of scavenging low-grade heat for low cost. The materials properties comprising ZT: thermal conductivity, electrical conductivity and Seebeck coefficient will be discussed for undoped, p-type and n-type silicon nanowire networks with particular emphasis on electrical conductivity and Seebeck coefficient within the temperature range of low-grade heat.