Assessing the limitations of transparent conducting oxides as thermoelectrics

Abstract

Many TCOs are limited as thermoelectrics by their long phonon mean free paths. We demonstrate the importance of computational analysis of lattice thermal conductivity for pinpointing which materials are effective targets for nanostructuring.

Ca4Sb2O and Ca4Bi2O: two promising mixed-anion thermoelectrics

“…20,21 Though there has been considerable progress in this area, the maximum ZT of even the best materials remain quite low compared to other thermoelectrics, typically due either to a moderate electrical conductivity or a high thermal conductivity. 22,23 Recently, we reported the promising thermoelectric properties of the room temperature polymorph of Bi 2 Sn 2 O 7 , which we found to have an ultralow intrinsic lattice thermal conductivity of ∼0.4 W m −1 K −1 and a ZT of 0.18 with n-type doping. 24 Although this ZT is the highest ever obtained for an oxide material at room temperature, Bi 2 Sn 2 O 7 may not be suitable for high-temperature applications as it undergoes a phase transition above 390 K.…”

α-Bi2Sn2O7: a potential room temperature n-type oxide thermoelectric

“…One of the main contributors to the low ZT values of these structures is their high thermal conductivity, 20 which has also been established as a limiting factor in the thermoelectric performance of transparent conducting oxides. 21 Various attempts at alloying, substitution and nanostructuring have been made to reduce k within these structures, 22,23 but have not been fruitful, with k remaining larger than 1 W m À1 K À1 at room temperature.…”

Ca4Sb2O and Ca4Bi2O: Two Promising Mixed-Anion Thermoelectrics

“…20,21 Though there has been considerable progress in this area, the maximum ZT of even the best materials remain quite low compared to other thermoelectrics, typically due either to a moderate electrical conductivity or a high thermal conductivity. 22,23 Recently, we reported the promising thermoelectric properties of the room temperature polymorph of Bi 2 Sn 2 O 7 , which we found to have an ultralow intrinsic lattice thermal conductivity of ∼0.4 W m −1 K −1 and a ZT of 0.18 with n-type doping. 24 Although this ZT is the highest ever obtained for an oxide material at room temperature, Bi 2 Sn 2 O 7 it is not suitable for high-temperature applications as it undergoes a phase transition above 390 K.…”