Construction of nano-lamellar expressways and multidimensional defects to realize the decoupling of carrier–phonon transport in BiSbSe1.25Te1.75

Abstract

BiSbSe_1.25Te_1.75, a typical multi-layered compound, has great potential for use in the manufacture of high-efficiency thermoelectric conversion devices due to its ability to be fabricated with p–n junctions of identical chemical composition by defect engineering. However, the thermoelectric properties of n-type BiSbSe_1.25Te_1.75 remain limited due to its poor electrical transport properties. Herein, we report an effective strategy to decouple its electrical and thermal transport properties, which can be realized by simple hot deformation of BiSbSe_1.25Te_1.75. Nanoscale lamellar structures with large surface areas and strongly preferred orientation formed by preferred growth along the ab planes provide expressways for electron transport. These structures are beneficial for promoting S while maintaining high σ because the expressways will effectively reduce the sacrifice through μ_H. Meanwhile, multidimensional defects are also introduced into samples by hot deformation, evoking strong scattering locations for phonons of different frequencies. Benefiting from the decoupling of carrier–phonon transport via hot deformation, a high average ZT value of 0.53 from 323 to 550 K (∼112% increase) and a high ZT value of 0.60 at 470 K (∼107% increase) are achieved in BiSbSe_1.25Te_1.75. This work undoubtedly paves the way for the utilization of TE materials with identical chemical composition in the fabrication of well-matched p–n junctions.