High thermoelectric performance in Cu-doped Bi2Te3 with carrier-type transition. (15th September 2018)

• Record Type: Journal Article
• Authors: Wu, Hsin-Jay; Yen, Wan-Ting
• Is Part Of: Acta materialia. Volume 157(2018)
• Page Start: 33
• Page End: 41
• Publication Date: 2018-09-15
• Subjects: Bi2Te3 -- Thermoelectric (TE) -- Isothermal section -- Bi-Cu-Te -- Carrier type transition; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2018.07.022
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: For decades, the Bismuth-telluride (Bi2 Te3 ) has been intensively studied as the thermoelectric (TE) cooler. Still, new ideas and emerging results are put forward for raising the conversion efficiency. Herein, we re-visit the Cu-doped Bi2 Te3, and report the high zT values nearing the room temperature, for both the p -type (Cu2 Te)0.01 (Bi2 Te3 )0.99 /Cu0.01 Bi1.99 Te3 ( zT ∼1.2 at 300 K) as well as the n -type (Cu2 Te)0.09 (Bi2 Te3 )0.91 ( zT ∼1.09 at 363 K), respectively. Given that the phase boundary mapping is essential for the optimization of high-efficiency TE materials, the isothermal section of ternary Bi-Cu-Te at 523 K is constructed, by collecting the phase equilibria information of various thermally-equilibrated alloys; it further guides the alloying directions for (Cu2 Te)x (Bi2 Te3 )1-x and Cuy Bi2-y Te3, respectively. Small modulation in the stoichiometry leads to the carrier type transition. As a consequence, the lamellae composed of Bi2 Te3 and Cu7 Te5 precipitate along the grain boundary of the n -type (Cu2 Te)0.09 (Bi2 Te3 )0.91, resulting in the reduced κ, due to the stronger interfacial phonon scattering, and the higher PF, owing to the higher amounts of Te vacancy (VTe ). On the contrary, the promising p -type (Cu2 Te)0.01 (Bi2 Te3 )0.99 /Cu0.01 Bi1.99 Te3 features the single-phase Bi2 Te3, whereas the soluble Cu introduces extra holes and might therefore promote the p -type conduction. Graphical abstract: Image 1