Enhanced thermoelectric performance of n-type Cu0.008Bi2Te2.7Se0.3 by band engineering. Issue 40 (3rd September 2015) - Lee, Kyu Hyoung
Abstract : We herein report the significantly improved thermoelectric performance of n-type Bi2 Te2.7 Se0.3 polycrystalline bulks through band structure engineering achieved by Au-doping. Abstract : We herein report the significantly improved thermoelectric performance of n-type Bi2 Te2.7 Se0.3 polycrystalline bulks through band structure engineering achieved by Au-doping. The Seebeck coefficient can be increased for both Bi2 Te2.7 Se0.3 and Cu-intercalated Bi2 Te2.7 Se0.3 bulks by doping Au on the Bi site, either due to the addition of the resonant state or the enhancement of density of states (DOS) effective mass m d *. Theoretical calculations combined with experimental measurements showed that band engineering connected with chemical potential tuning results in higher DOS at the bottom of the conduction band and increases the m d * from ∼0.88 m 0 (Bi2 Te2.7 Se0.3 ) to ∼1.06 m 0 (Cu0.008 Bi1.99 Au0.01 Te2.7 Se0.3 ). As a consequence, a peak thermoelectric figure of merit ZT ∼0.91 was obtained at 320 K for Cu0.008 Bi1.99 Au0.01 Te2.7 Se0.3, which is ∼40% and ∼25% enhancement in comparison with Bi2 Te2.7 Se0.3 and Cu0.008 Bi2 Te2.7 Se0.3, respectively.