Matrix plainification leads to high thermoelectric performance in plastic Cu2Se/SnSe composites

Abstract

Thermoelectric technology exhibits significant potential for power generation and electronic cooling. In this study, we report the achievement of exceptional thermoelectric performance and high plasticity in stable Cu₂Se/SnSe composites. A novel matrix plainification strategy was employed to eliminate lattice vacancies within the Cu₂Se matrix of the Cu₂Se/SnSe composites, resulting in a marked improvement in carrier mobility and power factor. The presence of quasi-coherent interfaces induces phonon scattering, reducing lattice thermal conductivity without compromising carrier mobility. Consequently, a high figure of merit (ZT) of 3.3 was attained in the Cu₂Se/5 wt.% Sn_0.96Pb_0.01Zn_0.03Se composite. Additionally, the presence of high-density nanotwins imparts remarkable plasticity to the composite, yielding a compressive strain of 12%. The secondary phase contributes to the stability of the composite by hindering the extensive migration of Cu ions through bonding interactions. Our findings present a novel strategy for enhancing the thermoelectric performance of composite semiconductors, with potential applicability to other thermoelectric systems.