Novel n-type thermoelectric material of ZnIn2Se4

Abstract

Besides enhancing thermoelectric performance of the existing thermoelectric materials, many efforts have been focused on the exploration of novel thermoelectric materials with potentially high performance typically. This is largely guided by the concept of the intrinsic low lattice thermal conductivity, which is arisen from various mechanisms, such as intrinsic vacancy, low sound velocity, complex crystal structure and lattice anharmonicity. Motivated by the inherent feature of highly disorder cations and intrinsic vacancies introducing strong lattice anharmonicity, this work focuses on a semiconducting compound, ZnIn2Se4, as a potential thermoelectric material. Pristine ZnIn2Se4 shows an n-type conduction and a low carrier concentration of 2.8 × 1018 cm−3. A lattice thermal conductivity as low as ∼0.9 W/m*K at high temperature is obtained, due to the additional phonon scattering by highly disorder cations and intrinsic vacancies. Thus, a peak zT of ∼0.23 is demonstrated in pristine ZnIn2Se4 even with the carrier concentration far deviating from the optimum. This work not only indicates this compound as a promising n-type thermoelectric material, but also provides a direction for enhancement of zT.