host: Phil Allen

\ntitle: **Carrier lifetime eff
ects on thermoelectric efficiency**

abstract

\nRecent
developments in electronic structure algorithms based on the Wannier func
tion interpolation of electronic wave functions have enabled accurate firs
t-principles calculations of electron-phonon interactions and intrinsic ca
rrier lifetimes in the relaxation time approximation. This has supplied th
e final missing piece of the puzzle for predicting the thermoelectric figu
re of merit zT=s S^{2} T/k\, where the conductivity s\, the Seebec
k coefficient S\, and the total thermal conductivity k now can all be obta
ined from the density-functional theory (DFT). This opens up exciting poss
ibilities for theoretically understanding and reliably predicting new mate
rials with high values of zT. We will review several examples from our rec
ent work\, including a Li-intercalated analogue of lead telluride (Li_{
2}TlBi)\, an intermetallic compound with unexpectedly high value of S
(CoSi)\, and a theoretically predicted full Heusler compound with ultrahi
gh zT (Ba_{2}BiAu). General factors for high thermoelectric power
factors in these compounds include energy dependence of carrier lifetimes
for high S\, high degeneracy of carrier pockets at the Fermi level\, weak
electron-phonon scattering for high mobility\, and concomitantly low Loren
tz numbers for low electronic thermal conductivity.