Achieving n- and p-type thermoelectric materials with the identical chemical composition BiSbTe1.5Se1.5 by defect structure engineering

Abstract

The outstanding thermoelectric devices for large-scale applications and high-efficiency conversions are more prone to homojunction structures in order to avoid lattice mismatch incompatibility and harmful band misalignment. ​Although a wide variety of thermoelectric materials have been investigated to date, the developed thermoelectric solid-state electronic systems comprise n- and p-type semiconductors coupled in different chemical compositions only instead of similar compositions. Here, n- and p-type thermoelectric materials with the same chemical composition have been creatively designed. The single-unit layered structure Sb2Se3 is chosen as the matrix material, wherein the substitutions of Sb by Bi and Se by Te atoms led to isoelectronic atomic-scale point defects in the lattice. Furthermore, crystal plane slip and donor-like effect are introduced by adjusting the deformation and hot pressing. Antisite defects, vacancies, dislocations, and nanoprecipitates are integrated into the structure by defect engineering. Consequently, n- and p-type thermoelectric materials with the same nominal chemical composition BiSbTe1.5Se1.5 are obtained simultaneously. The ZT values exceeding 0.21 at 300 K and the peak ZT values of 0.45 and 0.35 at 475 and 375 K for the n- and p-type BiSbTe1.5Se1.5 bulk sample (perpendicularl to the pressure direction) are achieved, respectively. This work undoubtedly opens a new door for the rational designing and construction of high-performance thermoelectric devices.