Improved thermoelectric properties for solution grown Bi2Te3−xSex nanoplatelet composites

Abstract

We herein report the large-scale synthesis of Bi₂Te_3−xSe_x (0.6 ≤ x ≤ 0.75) nanoplatelets through a hydrothermal method and subsequent spark plasma sintering. The effect of selenium alloying and the spark plasma sintering temperature on the thermoelectric properties of the Bi₂Te₃ nanostructured bulk materials were investigated. The results indicate that compared to samples fabricated in an autoclave, preparing Bi₂Te_3−xSe_x in glass beaker with suitable Se alloying and appropriate sintered temperature is an efficient way to reduce the lattice thermal conductivity due to a large number of Bi₂TeO₅ nanodots with sizes of around 10 nm. Meanwhile, a decrease in electrical resistivity due to increase in carrier mobility and an enhancement of the Seebeck coefficient attribute to decrease in carrier concentration were observed. As a result, the thermoelectric figure-of-merit, ZT, is significantly improved and the maximum value reaches 0.96 for Bi₂Te_2.25Se_0.75 at 490 K.