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

Ag2Se 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 Ag2Se, 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 Ag2Se/AgSbSe2 composite architectures with uniform distribution of AgSbSe2 inclusions, which was realized by sintering solution-synthesized mixtures of Ag2Se nano/micro-particles and Sb2Se3 nanorods. Particulate AgSbSe2 and as-built Ag2Se/AgSbSe2 interfaces enable intensified phonon scattering and impeded crack propagation, and refined grain size additionally contributes to optimized thermal and mechanical properties. As a result, (Ag2Se)0.98(2AgSbSe2)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 Ag2Se 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 Ag2Se.