Preparation, structural characteristics and optical parameters of the synthesized nano-crystalline sulphur-doped Bi2Te2.85Se0.15 thermoelectric materials

Abstract

In the present work, a systematic preparation of Bi 2 Te 2.85 Se 0.15-x S x (x=0.0, 0.02, 0.04 and 0.06) compositions were carried out by solvothermal method. The materials were characterized by XRD, SEM, EDX, TEM and Raman spectroscopy.XRD, as well as TEM, to confirm the nanostructure of samples. The electrical and thermal properties were investigated in the temperature range from room temperature to 600 K. The highest power factor was 1.3 x 10 -2 mW/ K 2 m at 600 K for (x=0.06) sample. This improvement in the thermoelectric properties may be due to the ordered atomic arrangement of Bi, Te, and Se induced by sulphur in the Bi 2 Te 2.85 Se 0.15-x S x nano-composites, which was confirmed by X-ray diffraction (XRD) and Raman spectral analysis. The optical properties, such as energy gap, refractive index, extinction coefficient and dielectric constants, were obtained from the diffused reflectance data in the range of 200 to 800 nm. Sulphur doping influences the optical energy gap, reaching the lowest value for x=0.04 samples (0.14 eV), while the highest allowed energy gap was found in x=0.06 ones (0.41eV).

Improved thermoelectric performance of Bi2Se3 alloyed Bi2Te3 thin films via low pressure chemical vapour deposition

“…An alternative to the replacement of Bi2Te3 is to reduce the volume of material required to achieve the same or higher performance. For example, partial replacement of the low natural abundance of tellurium by selenium contributes strongly to a sustainable thermoelectric solution [15][16][17]. Several groups have produced ternary Bi2Te3-xSex thin films via electrodeposition [18][19][20][21][22][23][24][25], pulsed laser deposition [26], sputtering [27,28], and thermal evaporation [29][30][31].…”