Details

Autor(en) / Beteiligte

• Guo, Zhe
• Wu, Gang
• Tan, Xiaojian
• Wang, Ruoyu
• Zhang, Zongwei
• Wu, Guangjie
• Zhang, Qiang
• Wu, Jiehua
• Liu, Guo‐Qiang
• Jiang, Jun

Titel

Enhanced Thermoelectric Performance in GeTe by Synergy of Midgap state and Band Convergence

Ist Teil von

• Advanced functional materials, 2023-03, Vol.33 (11), p.n/a

Ort / Verlag

Hoboken: Wiley Subscription Services, Inc

Erscheinungsjahr

2023

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The good co‐existence of midgap state and valence band degeneracy is realized in Bi‐alloyed GeTe through the In‐Cd codoping to play different but complementary roles in the valence band structure modification. In doping induces midgap state and results in a considerably improved Seebeck coefficient near room temperature, while Cd doping significantly increases the Seebeck coefficient in the mid‐high temperature region by promoting the valence band convergence. The synergistic effects obviously increase the density of state effective mass from 1.39 to 2.65 m0, and the corresponding carrier mobility still reaches 34.3 cm2 V−1 s−1 at room temperature. Moreover, the Bi‐In‐Cd co‐alloying introduces various phonon scattering centers including nanoprecipitates and strain field fluctuations and suppresses the lattice thermal conductivity to a rather low value of 0.56 W m−1 K−1 at 600 K. As a result, the Ge0.89Bi0.06In0.01Cd0.04Te sample obtains excellent thermoelectric properties of zTmax ≈2.12 at 650 K and zTavg ≈1.43 between 300 and 773 K. This study illustrates that the thermoelectric performance of GeTe can be optimized in a wide temperature range through the synergy of midgap state and valence band convergence. It is revealed that the good coexistence of midgap state and band convergence in GeTe improves the thermoelectric performance over a very broad temperature range. Since the high md∗$m_d^ * $ is obtained and the κl is reduced, the thermoelectric performance of GeTe is significantly improved, leading to a high zTmax of 2.12 at 650 K and a greatly improved zTavg of 1.43 between 300 and 773 K.