Fine-Tuning Bi 2 Te 3 -Copper Selenide Alloys Enables an Efficient n-Type Thermoelectric Conversion.

Bismuth tellurides is one of the most promising thermoelectric (TE) material candidates in low-temperature application circumstances, but the n-type thermoelectric property is relatively low compared to the p-type counterpart and still needs to be improved. Herein, we incorporated different copper selenides (CuSe, Cu 3 Se 2 and Cu 2-x Se) into a Bi 2 Te 3 matrix to create the alloy by grinding and successive sintering to enable higher thermoelectric performance. The results demonstrated that all alloys achieved n-type TE characteristics and Bi 2 Te 3 -CuSe exhibited the best Seebeck coefficient and power factor among them. Along with the low thermal conductivity, the maximum dimensionless TE figure of merit (ZT) value of 1.64 at 573 K was delivered for Bi 2 Te 3 -CuSe alloy, which is among the best reported results in the n-type Bi 2 Te 3 -based TE materials to the best of our knowledge. The improved TE properties should be related to the co-doping process of Se and Cu. Our investigation shows a new method to enhance the performance of n-type TE materials by appropriate co-doping or alloying.