High Thermoelectric Performance in Crystallographically Textured n-Type Bi2Te3–xSex Produced from Asymmetric Colloidal Nanocrystals

• DOI: 10.1021/acsnano.8b03099
• Publication Date: 2018-07-02T21:04:34Z
• Authors: Yu Liu; Yu Zhang; Khak Ho Lim; Maria Ibáñez; Silvia Ortega; Mengyao Li; Jérémy David; Sara Martí-Sánchez; Ka Ming Ng; Jordi Arbiol; Maksym V. Kovalenko; Doris Cadavid; Andreu Cabot
• Keywords: Tellurium; Hot pressing; Nanomaterials

In the present work, we demonstrate crystallographically textured n-type Bi2Te3–xSex nanomaterials with exceptional thermoelectric figures of merit produced by consolidating disk-shaped colloidal nanocrystals (NCs). Crystallographic texture was achieved hot pressing asymmetric NCs in presence an excess tellurium. During press, tellurium acted both as lubricant to facilitate rotation lying close normal pressure axis and solvent dissolve approximately aligned direction, which afterward recrystallize a preferential orientation. NC-based showed very high electrical conductivities associated large charge carrier concentrations, n. We hypothesize that such n resulted from during processing, introduced density donor TeBi antisites. Additionally, between grains traces elemental Te, narrow band gap semiconductor work function well below Bi2Te3–xSex, might further contribute increase through spillover electrons, while at same time blocking phonon propagation hole transport nanomaterial. were characterized low thermal ZT values up 1.31 438 K this direction. This corresponds ca. 40% enhancement commercial ingots. extended over wider temperature ranges due reduced bipolar contribution Seebeck coefficient conductivity. Average 1.15 wide range, 320 500 K, measured, 50% materials range. Contrary most previous works, highest obtained corresponding c crystallographic axis, predominance conductivity reduction difference when comparing two crystal directions.