1. Materials for Thermoelectric Applications Jorge O. Sofo Department of Physics, Department of Materials Science and Engineering, and Materials Research Institute Penn State

3. Thermoelectricians at work

5. Conductivity 101 Drude et al. k-q q k

6. kxkx kyky Conductivity 101

21. Transport distribution

22. “The best thermoelectric,” G. D. Mahan and J. O. Sofo Proc. Nat. Acad. Sci. USA, 93, 7436 (1996)

23. The “Best” Thermoelectric

24. Exciting Conductivity First Born Approximation Acoustic phonons Optical phonons (polar, non-polar) Ionized impurities Inter-valley scattering … C. Ambrosch-Draxl and J. O. Sofo Linear optical properties of solids within the full-potential linearized augmented planewave method Comp. Phys. Commun. 175, 1-14 (2006)

25. Careful… Doping: rigid band Gap problem Temperature dependence of the electronic structure. Alloys. Single site approximations do not work. Many k-points

26. T. J. Scheidemantel, C. Ambrosch-Draxl, T. Thonhauser, J. V. Badding, and J. O. Sofo. “Transport Coefficients from First-principles Calculations.” Phys. Rev. B 68, 125210 (2003) Bi 2 Te 3

28. Bismuth

29. Why is Bi so good?

30. Bi vs. Bi 2 Te 3 Improved thermoelectric devices using bismuth alloys T. Thonhauser, T. J. Scheidemantel, J. O. Sofo, Appl. Phys. Lett. 85, 588 (2004)

31. Is there any hope?

32. Courtesy of Georg Madsen A Program by Georg Madsen and David Singh

33. Courtesy of Georg Madsen

34. Georg Madsen’s

39. Opals Different scattering for phonons and electrons. Work done for Allied Signal Corp. Not an alternative… 

40. Summary Tool to explore new compounds, pressure, “negative” pressure. Prediction of a new compound by G. Madsen. Easy to expand adding new Scattering Mechanisms Limited to applications on “non-correlated” semiconductors. The search for the best material continues…