ZT thermoelectrics Alex Ganose, Winnie Leung, Adam Jackson, Robert Palgrave and David Scanlon Department of Chemistry, University College London Diamond Light Source Ltd. &
such great TCOs? Overlap of metal s states with O 2p Can we find alternatives? Post transition metal (V) oxides: – Cheaper than In & Sn – Large EAs & small me * – Heavy elements help lower κ latt
~2.6 eV Dispersive CBM (Bi s states) gives low effective masses: – 0.37 me in layers, 0.67 me across layers Ideal electronic structure for n-type material
at 450 K – ZT ~ 0.2 at 600 K – Doping levels are realistic using La as dopant Better performance than state-of-the art SrTiO3 (0.15 at 600 K) Limited by relatively small temperature stability range Rosseinsky and coworkers, Ener. Environ. Sci. (2017), 10, 1917–1922
structure (P42 /mnm) – Proposed as TCO in 2005 (Hosono group) and 2014 (Hautier group) – Sb5+ more resistant to reduction than Bi5+ – Stable to 1400 K!
at 1000 K – ZT ~ 0.65 at 1400 K Doping levels realistic: 4 x 1019 cm–3 Better performance than any n-type TE: – In2 O3 :Ge ~ 0.48 at 1300 K – Zn0.98 Al0.02 O ~ 0.30 at 1300 K Maignan and coworkers, J. Phys. Condens. Matter (2016), 28, 013001
Good dispersion similar to other (n –1)d10ns0np0 oxides – Large fundamental & optical band gaps BaBi2 O6 : – Low κ latt due to layered nature; dopable with La – ZT comparable with SrTiO3 at low temperature ZnSb2 O6 : – κ latt remains low & Al enables high doping concentration – Highest predicted ZT of any n-type oxide TE