Entropy engineering promotes thermoelectric performance while realizing P–N switchable conduction in BiSbSe1.5Te1.5

Abstract

BiSbSe1.5Te1.5, a typical multi-layered compound, can be utilized to fabricate p-n junctions with the identical chemical composition by regulating the antisite defects and anion vacancies via defect engineering. However, the thermoelectric performance of n-type BiSbSe1.5Te1.5 is limited due to poor electrical transport properties. Entropy engineering is a novel strategy for expanding the space of performance optimization in materials science, including the field of thermoelectric. Herein, we realize a largely enhanced thermoelectric performance for n-type BiSbSe1.5Te1.5 by employing entropy engineering. Both mass field fluctuations and stress variations field are introduced simultaneously in the lattice, leading to additional phonon scattering. Moreover, nano-laminate structure, nanoscale interstices and holes are formed in the samples. All of these defects and nanoscale structures are especially efficient on trapping phonons. As a result, the optimizing electrical transport properties while maintaining low thermal conductivity are achieved, showcasing a peak ZT of 0.54 at 475 K and a remarkable average ZT of 0.45 between 300 and 550 K for n-type BiSbSe1.25Te1.75.These findings not only provide a way to enhance the thermoelectric performance of n-type BiSbSe1.5Te1.5 but also push forward the promise of the applications in fabricating well-matched p-n junctions using thermoelectric materials with the identical chemical composition.