First-principles study on doping and temperature dependence of thermoelectric property of Bi2S3 thermoelectric material

Graphical abstract: The direction-induced ZT is found. At ZZ direction and n = 1.47 × 1019 cm−3, the ZT can reach maximal value, 0.36, which is three times as much as maximal laboratorial value. This result matches well the analysis of electron effective mass. Highlights: ► Electrical transportations of Bi2S3 depend on the concentration and temperature. ► The direction-induced ZT is found. ► At ZZ direction and n = 1.47 × 1019 cm−3, the ZT can reach maximal value, 0.36. ► The maximal ZT value is three times as much as maximal laboratorial value. ► By doping and temperature tuning, Bi2S3 is a promising thermoelectric material. - Abstract: The electronic structure and thermoelectric property of Bi2S3 are investigated. The electron and hole effective mass of Bi2S3 is analyzed in detail, from which we find that the thermoelectric transportation varies in different directions in Bi2S3 crystal. Along ac plane the higher figure of merit (ZT) could be achieved. For n-type doped Bi2S3, the optimal doping concentration is found in the range of (1.0–5.0) × 1019 cm−3, in which the maximal ZT reaches 0.21 at 900 K, but along ZZ direction, the maximal ZT reaches 0.36. These findings provide a new understanding of thermoelectricity-dependent structure factors and improving ZT ways. The donor concentration N increases as T increases at one bar of pressure under a suitable chemical potential μ, but above this chemical potential μ, the donor concentration N keeps a constant