Engineering of Thermoelectric Composites Based on Silver Selenide in Aqueous Solution and Ambient Temperature
Bingfei Nan, Mengyao Li, Yu Zhang, Ke Xiao, Khak Ho Lim, Cheng Chang, Xu Han, Yong Zuo, Junshan Li, Jordi Arbiol, Jordi Llorca, María Ibáñez, Andreu Cabot
Abstract
High Resolution Image Download MS PowerPoint Slide The direct, solid state, and reversible conversion between heat and electricity using thermoelectric devices finds numerous potential uses, especially around room temperature. However, the relatively high material processing cost limits their real applications. Silver selenide (Ag 2 Se) is one of the very few n-type thermoelectric (TE) materials for room-temperature applications. Herein, we report a room temperature, fast, and aqueous-phase synthesis approach to produce Ag 2 Se, which can be extended to other metal chalcogenides. These materials reach TE figures of merit ( zT ) of up to 0.76 at 380 K. To improve these values, bismuth sulfide (Bi 2 S 3 ) particles also prepared in an aqueous solution are incorporated into the Ag 2 Se matrix. In this way, a series of Ag 2 Se/Bi 2 S 3 composites with Bi 2 S 3 wt % of 0.5, 1.0, and 1.5 are prepared by solution blending and hot-press sintering. The presence of Bi 2 S 3 significantly improves the Seebeck coefficient and power factor while at the same time decreasing the thermal conductivity with no apparent drop in electrical conductivity. Thus, a maximum zT value of 0.96 is achieved in the composites with 1.0 wt % Bi 2 S 3 at 370 K. Furthermore, a high average zT value ( zT ave ) of 0.93 in the 300–390 K range is demonstrated.