title: Surfactant-free synthesis of Bi2Te3-Te micro-nano heterostructure with enhanced thermoelectric figure of merit.
abstract: An ideal thermoelectric material would be a semiconductor with high electrical conductivity and relatively low thermal conductivity: an "electron crystal, phonon glass". Introducing nanoscale heterostructures into the bulk TE matrix is one way of achieving this intuitively anomalous electron/phonon transport behavior. The heterostructured interfaces are expected to play a significant role in phonon scattering to reduce thermal conductivity and in the energy-dependent scattering of electrical carriers to improve the Seebeck coefficient. A nanoparticle building block assembly approach is plausible to fabricate three-dimensional heterostructured materials on a bulk commercial scale. However, a key problem in applying this strategy is the possible negative impact on TE performance of organic residue from the nanoparticle capping ligands. Herein, we report a wet chemical, surfactant-free, low-temperature, and easily up-scalable strategy for the synthesis of nanoscale heterophase Bi(2)Te(3)-Te via a galvanic replacement reaction. The micro-nano heterostructured material is fabricated bottom-up, by mixing the heterophase with commercial Bi(2)Te(3). This unique structure shows an enhanced zT value of ∼0.4 at room temperature. This heterostructure has one of the highest figures of merit among bismuth telluride systems yet achieved by a wet chemical bottom-up assembly. In addition, it shows a 40% enhancement of the figure of merit over our lab-made material without nanoscale heterostructures. This enhancement is mainly due to the decrease in the thermal conductivity while maintaining the power factor. Overall, this cost-efficient and room-temperature synthesis methodology provides the potential for further improvement and large-scale thermoelectric applications.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, USA.
authors.forename: Yichi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Heng
authors.initials: H
authors.lastname: Wang
authors.forename: Stephan
authors.initials: S
authors.lastname: Kräemer
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Shi
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Matt
authors.initials: M
authors.lastname: Snedaker
authors.forename: Kunlun
authors.initials: K
authors.lastname: Ding
authors.forename: Martin
authors.initials: M
authors.lastname: Moskovits
authors.forename: G Jeffrey
authors.initials: GJ
authors.lastname: Snyder
authors.forename: Galen D
authors.initials: GD
authors.lastname: Stucky