Optimizing the cooling performance of lead telluride by doping silver

Abstract

Thermoelectric materials are widely employed in different areas, like deep space exploration for power generation and cooling in the thermal management of electronics. To obtain excellent performance in thermoelectric system, the materials are required to own great properties such as ZT at suitable temperature. Normal room-temperature materials like bismuth telluride may suffer from efficiency reduction of power generation or cooling, because of significant variation of ZT from 300K to 500K. Nowadays, it may be resolved by using another material lead telluride (PbTe) which is usually seen as a mid-temperature material in previous work. Recently, researchers have found that lead chalcogenides including PbTe can refrigerate near room temperature. Furthermore, we doped PbTe with silver (Ag) and found it possessed stable cooling efficiency owing to the smooth ZT from 300K to 523K. Through synthesizing a set of p-type Pb_1-xAg_xTe-5 at.% Te (x = 0–0.02) samples by melting and hot-press technology in Te-rich condition, we discovered the ZT was about 0.4 at 300K along with the average one reaching 0.38 and kept stable from 300K to 523K. Besides, the virtual thermoelectric cooler consisting of the 7-pair p-n junction showed the △T_max and COP_max values can reach 54.9K and 9.3 % at 300K, respectively. This investigation highlights that the PbTe-based composition with silver dopant has the potential for refrigerating devices at or near room temperature in the future.