Simultaneous enhancement of thermoelectric and mechanical performance in Ag₂Se via Sb₂Te₃ compositing

Silver Selenide (Ag₂Se) has been deemed as an excellent candidate for substitution of the n-type Bi₂Te₃ for thermoelectric applications. However, the naturally high electron concentration resulting from interstitial cation and inferior mechanical performance of pristine Ag₂Se significantly limit its practical application. Additionally, the conventional synthesis of Ag₂Se commonly requires complex and time-consuming high temperatures melting or ball milling processes. In this study, Ag₂Se composited with Sb₂Te₃ was synthesized through a simple manual mixing followed by a hot press sintering method. By introducing microparticle Sb₂Te₃, the carrier concentration of Ag₂Se was suppressed and thus the Seebeck coefficient and Hall mobility were enhanced simultaneously. Furthermore, the presence of particulate Sb₂Te₃ and the interfaces formed between Ag₂Se and Sb₂Te₃ intensified phonon scattering and impeded crack propagation. These lead to a suppression in thermal conductivity accompanied by an improvement in hardness. Consequently, an enhanced zT of 0.92 and an improved hardness of 71 Kgf·mm⁻² were achieved for Ag₂Se composited with 2 mol% and 3mol% Sb₂Te₃, which were approximately 30 % and 18 % higher than those of the pristine Ag₂Se, respectively. These results indicate that combining manual mixing with the introduction of secondary-phase particles provides a facile approach to simultaneously optimize both the thermoelectric and mechanical performance of Ag₂Se.