AgSbSe2 inclusions enabling high thermoelectric and mechanical performance in n-type Ag2Se-based composites

Ag ₂ Se is a promising near-room-temperature thermoelectric material with prospective applications in solid-state cooling and waste heat recovery. To advance the practical application of Ag ₂Se, it is imperative yet challenging to further boost its average dimensionless figure of merit ( zT) and mechanical performance. Herein, we effectively enhance the two types of performance by constructing Ag ₂Se/AgSbSe ₂ composite architectures with uniform distribution of AgSbSe ₂ inclusions, which was realized by sintering solution-synthesized mixtures of Ag ₂Se nano/micro-particles and Sb ₂Se ₃ nanorods. Particulate AgSbSe ₂ and as-built Ag ₂Se/AgSbSe ₂ interfaces enable intensified phonon scattering and impeded crack propagation, and refined grain size additionally contributes to optimized thermal and mechanical properties. As a result, (Ag ₂Se) _0.98(2AgSbSe ₂) _0.02 composite approaches a low lattice thermal conductivity of 0.15 W m ^–1 K ^–1 at 375 K and an excellent average zT of ∼0.89 between 300 and 375 K; mechanically, this composite obtains a compressive strength of 197.3 MPa, which is improved by ∼125% compared to that of Ag ₂Se and represents the highest value ever reported for this compound. This study sheds light on the efficacy of introducing secondary-phase particles on simultaneously boosting the thermoelectric and mechanical performance of Ag ₂Se.