Construction of Nano-Lamellar Expressways and Multidimensional Defects Realizes 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 the fabrication of high-efficiency thermoelectric conversion devices due to its ability to fabricate p-n junctions with identical chemical composition by defect engineering. However, the thermoelectric properties of n-type BiSbSe_1.25Te_1.75 remain limited due to the poor electrical transport properties. Herein, we report an effective decouple strategy between the electrical and thermal transport properties, which can be realized by a simple hot deformation for BiSbSe_1.25Te_1.75. Nanoscale lamellar structures with large surface areas and strongly preferred orientation formed by the preferred growth along the ab planes provides expressways for electron transport. It is beneficial to promoting the S while maintaining the high σ because expressways will effectively reduce the sacrifice in μ_H. Meanwhile, multidimensional defects are also introduced into hot deformation samples, evoking a strong scattering for phonons with 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% increased) and a high ZT value of 0.60 at 470 K (~ 107% increased) are achieved in BiSbSe_1.25Te_1.75. This work undoubtedly paves the way for the utilization of TE materials with identical chemical composition to fabricate well-matched p-n junctions.