Enhanced thermoelectric performance of n-type Bi2(Se, Te)3 bulk nanocomposites through Ti doping

Improving the performance of thermoelectric (TE) materials and fabricating TE devices with higher conversion efficiency remains a significant challenge in materials research. The low figure of merit (ZT) value of n-type bismuth telluride has seriously hindered the development of TE devices based on bismuth telluride. Element doping and nanostructured defect introduction have commonly been employed to improve TE properties. Herein, we utilized high-pressure synthesis to fabricate n-type Bi2Se0.3Te2.7 bulk nanomaterials and enhance their TE performance by adjusting the fabrication pressure and titanium doping concentration. Through this process, titanium effectively substituted bismuth to decrease carrier concentration and improve carrier mobility. As a result, the thermal conductivity was significantly decreased. By employing a fabrication pressure of 2.5 GPa and 10 at % Ti doping, a remarkable ZT value of 0.96 was achieved at 333 K, which was 2.8 times the undoped counterparts. These findings demonstrate a successful design methodology and fabrication process to generate n-type Bi2Te3 with outstanding TE performance. This study provided valuable insights into the synthesis of high-performance TE materials and contributed to advancements in TE device technology.