Enhancing Thermoelectric Performance of AgSbTe2 via Boron Doping and Composition Tuning

Developing thermoelectric materials for medium-temperature applications is crucial for sustainable energy technologies. AgSbTe2 stands out due to its intrinsically low thermal conductivity. However, its application is hindered by n-type Ag2Te impurities. In this study, we introduce a ball-milling and low-temperature annealing technique to synthesize AgSbTe2 and successfully suppress Ag2Te formation through boron doping and composition modification. The suppression of Ag2Te is confirmed by SEM and TEM studies along with the linear temperature dependence of the carrier concentration, electrical conductivity, and power factor, indicating a stable electronic transport behavior. Ag2Te suppression enhances carrier concentration and electrical conductivity, leading to a temperature-independent power factor around 1.22 mWm–1K–2 between 300 and 625 K. Jonker plot analysis indicates that boron doping and composition modulation improve intrinsic electronic properties. TEM and Debye–Callaway modeling further reveal that enhanced dislocations are responsible for the reduction in the lattice thermal conductivity. Consequently, the figure of merit (zT) of the Ag0.91Sb1.09Te2.09 + 0.025 wt % B sample increased to 1.35 at 573 K, while the average zT increased to 1.03. Our approach yields a competitive zT value, highlighting the effectiveness of boron doping and composition tuning in enhancing AgSbTe2 for medium-temperature power generation applications, supported by single-leg measurements.