Thermoelectric performance enhancement in BiSbTe composites with Silicon inclusions
Tian-Wey Lan1,2,3*, Chung-Chieh Chang1, Yu-Chieh Chien1, Yao-Tsung Hsieh1, Yu-Ruei Wu1, Min-Hsueh Wen1, Chuan-Ming Tseng1, Ting-Kuo Lee1, Maw-Kuen Wu1,4, Yang-Yuan Chen1
1Institute of Physics, Academia Sinica, Taipei, Taiwan
2Department of Physics, National Taiwan University, Taipei, Taiwan
3Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan University, Taipei, Taiwan
4Institute of Physics, National Dong Hwa University, Hualien, Taiwan
* presenting author:Tianwey Lan,
In the last few years, the thermoelectric (TE) materials have been broadly investigated due to their potential application in energy saving by generating electricity from waste heat. Bismuth antimony telluride (BiSbTe) and its alloys are the most promising commercial thermoelectric materials near the room temperature. To enhance the thermoelectric performance, one of the most effective ways is to optimize power factor of BiSbTe composites.
Hence, in this work, the effects of silicon(Si) inclusion in Bi0.5Sb1.5Te3 has been studied. The figure of merit (ZT) greater than 1.2 for a wide temperature range of 320 to 440 K with a peak zT = 1.3 at 375 K is obtained in SixBi0.5Sb1.5Te3 with x=0.03 due to an optimal carrier concentration of 2 x 1019 cm-3. The SixBiSbTe composites with varied x can be achieved through Bridgman method, milling and spark plasma sintering (SPS) process. Partial substitution of Si for Bi or Sb site results in an increase of carrier concentration and lattice constant. Compared with the Bi0.5Sb1.5Te3 alloy, zT value has been significantly improved in the composites with Si inclusions mainly due to the increased Seebeck coefficient and power factor. The consequence is explained through tunning the carrier concentration and mobility those are confirmed by the Hall measurement.

Keywords: thermoelectric, BiSbTe, carrier