Enhanced Thermoelectric Performance of Bi2Te2.7Se0.3/Bi2S3 Synthesized by Anion Exchange Method

Decoupling the electric conductivity, Seebeck coefficient, and thermal conductivity is a core issue to improve the properties of thermoelectric materials by tuning the electron and phonon transport properties. Herein, Bi2Te2.7Se0.3/Bi2S3 heterostructure is successfully synthesized by a simple anion exchange method with Bi2Te2.7Se0.3 as the starting material. The Bi2Te2.7Se0.3/Bi2S3 heterointerfaces can achieve an effective phonon scattering and significant decrease in thermal conductivity, while maintaining a high power factor, resulting in an enhanced figure of merit (ZT). By controlling the concentration of Bi2Te2.7Se0.3/Bi2S3 heterointerfaces, the carrier-transporting and phonon-scattering behaviors can be simultaneously optimized. A maximum ZT of 0.7 is obtained at 473 K, which is 23% higher than that of pure Bi2Te2.7Se0.3. In addition, the average ZT at 300-548 K increases from 0.49 to 0.61, which is 25% higher than that of pure Bi2Te2.7Se0.3.