Effects of different amount of Se-doping on microstructures and thermoelectric properties of n-type Bi2Te3-xSex

Abstract

A hydrothermal method combined with a subsequent spark plasma sintering technique was successfully utilized to synthesize selenium (Se) doped bismuth telluride (Bi2Te3-xSex) (0≤x≤0.45). The influence of Se-doping on the composition and morphology of n-type Bi2Te3-xSex was studied by X-ray diffraction, scanning electron microscope and transmission electron microscope. Thermoelectric properties of the as-prepared bulk Bi2Te3-xSex nanocomposites were investigated in detail. Results showed that the grain became finer by the Se-doping. With increasing Se doping content, the electrical conductivity of bulk Bi2Te3-xSex increased firstly and then decreased. Se-doping effectively reduced the thermal conductivity and improved the Seebeck coefficient to some extent. Consequently, a maximum ZT value of 0.57 was obtained from bulk Bi2Te2.7Se0.3 at 475 K, which was increased by 159% as compared with pure bulk Bi2Te3.