Doping effects on the thermoelectric properties of Cu₃SbSe₄
Chia-Hsiang Chang1,2*, Wan-Ting Chiu1, Cheng-Lung Chen1, Yang-Yuan Chen1,2
1Institute of Physics, Academia Sinica, Taipei 115, Taiwan
2Graduate Institute of Applied Physics, National Chengchi University, Taipei 116, Taiwan
* presenting author:C . H . Chang,
Cu₃SbSe₄ is a p-type semiconductor with a narrow band gap near 0.3 eV, and has been found to be a promising thermoelectric material at medium temperatures. The crystal structure of Cu₃SbSe₄ consists of the tetrahedral [SbSe4] and the three-dimensional Cu/Se framework ([Cu3Se4]) acting as the hole conduction pathway. The electrical conductivity of materials can be significantly tuned by doping proper atoms in Cu/Se framework. Meanwhile, the insertion of tetrahedral [SbSe4] will also led to a more distorted diamond-like structure, resulting in a relatively lower lattice thermal conductivity and a higher Seebeck coefficient. In spite of the knowledge that has already been known for Cu₃SbSe₄, further optimization by carefully controlling the types of defects and carrier concentrations is able to improve their power factor and thermal conductivity. According to recent theoretical predication based on the defect formation energy and band structure calculations, p-type doping can be achieved by substituting Sb with some group IV elements, and n-type doping can be done by replacing Cu by Zn or Mg. Herein, we take a close look at the thermoelectric properties of Cu₃SbSe₄ with above mentioned dopants. All samples were prepared by melting and spark plasma sintering. The crystal structures, microstructures and their transport behaviors will be presented and discussed.

Keywords: low lattice thermal conductivity, spark plasma sintering, substituting Sb with group IV elements, replacing Cu by Zn or Mg