Synergistic effect approaching record-high figure of merit in the shear exfoliated n-type Bi2O2-2xTe2xSe

Due to the nature of high stability and eco-friendliness, layered n-type Bi2O2Se-based thermoelectric materials have attracted extensive research interest. In order to reduce lattice thermal conductivity and enhance thermoelectric performance of Bi2O2Se-based thermoelectric materials, here, we introduced Te substitution at O site into Bi2O2-2xTe2xSe prepared by a shear exfoliation method. The induced high-density nanosized Bi2O2Se grains and point defects can effectively scatter both mid and short-wavelength phonons, leading to a low lattice thermal conductivity of similar to 0.57 W m(-1) K-1 at similar to 773 K. Furthermore, Se vacancies generated by the shear exfoliation induced a high carrier concentration approaching the optimized level, and in turn lead to relatively high electrical performance. The synergistic high electrical performance and low lattice thermal conductivity secured a record-high dimensionless figure of merit, zT, of similar to 0.69 at similar to 773 K. This study indicates that shear exfoliation method and Te substitution are promising methods to optimize the thermoelectric properties of Bi2O2Se-based thermoelectric materials.