Thermoelectric properties of Cu2Se1−xTex solid solutions

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2018, Vol.6 (16), p.6977-6986
• Main Authors: Zhao, Kunpeng, Guan, Mengjia, Qiu, Pengfei, Blichfeld, Anders B, Eikeland, Espen, Zhu, Chenxi, Ren, Dudi, Xu, Fangfang, Iversen, Bo B, Shi, Xun, Chen, Lidong
• Format: Article
• Language: English
• Subjects: Carrier density; Carrier mobility; Copper selenides; Electrical resistivity; Heat conductivity; Heat transfer; Physical properties; Q factors; Seebeck effect; Solid solutions; Thermal conductivity; Thermoelectric materials
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c8ta01313f

Binary Cu 2 Se and Cu 2 Te have gained great attention recently because of their interesting and abnormal physical properties, such as ultralow thermal conductivity, high carrier mobility, large effective mass of carriers and excellent thermoelectric performance. In this study, we find that these two compounds are completely miscible throughout the studied composition range. The trigonal structure of Cu 2 Se is maintained when the Te content x is 0.2, but a new trigonal structure is formed when the Te content x is between 0.3 and 0.7. The carrier concentration is greatly improved when increasing the Te content in Cu 2 Se 1− x Te x solid solutions, resulting in a much reduced electrical resistivity and Seebeck coefficient in the whole temperature range as compared with those of binary Cu 2 Se. The total thermal conductivity is inversely increased due to the contribution from enhanced carrier thermal conductivity. As a result, the overall thermoelectric performance of Cu 2 Se 1− x Te x solid solutions lies between Cu 2 Se and Cu 2 Te. We also find that the quality factor of Cu 2 Se 1− x Te x is higher than those of most typical thermoelectric materials. Thus the thermoelectric performance can be further improved if the intrinsically high hole carrier concentrations can be reduced in Cu 2 Se 1− x Te x . We demonstrate that the quality factor of Cu 2 Se 1− x Te x solid solutions is higher than those of most typical thermoelectric materials.