Matrix Plainification Leads to High Thermoelectric Performance in Plastic Cu2Se/SnSe Composites

Thermoelectric technology exhibits significant potential for applications in power generation and electronic cooling. In this study, we report the achievement of exceptional thermoelectric performance and high plasticity in stable Cu ₂ Se/SnSe composites. A novel matrix plainification strategy was employed to eliminate lattice vacancies within the Cu ₂ Se matrix of the Cu ₂ Se/SnSe composites, resulting in a marked improvement in carrier mobility. This increase in carrier mobility corresponds to a substantial enhancement of the power factor. Furthermore, the presence of quasi-coherent interfaces induces strong phonon scattering, which effectively reduces lattice thermal conductivity without compromising carrier mobility. Consequently, an outstanding figure of merit (ZT) of 3.3 was attained in the Cu ₂ Se/SnSe 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 significantly enhancing the thermoelectric performance of composite semiconductors, with potential applicability to other thermoelectric systems.