Synergistic effects of CuI doping on enhancing thermoelectric performance for n-type Bi2O2Se fabricated by mechanical alloying

The extremely low electrical conductivity and time-consuming preparation methods limit potential practical applications for Bi2O2Se-based thermoelectric materials. To solve these problems, a fast preparation method of combining mechanical alloying (MA) with spark plasma sintering (SPS) has been successfully adopted to syn-thesize CuI-doped Bi2O2Se in this work. The electrical conductivity was largely improved from 3 S cm-1 to 296 S cm-1 at 823 K attributed to the optimized carrier concentration. Meanwhile, an extremely low lattice thermal conductivity value of 0.39 W m-1 K-1 at 823 K was achieved by intensive phonon scatterings from point defects and dense grain boundaries. Consequently, an enhanced ZT value reached 0.45 at 823 K, which resulted in-380% improvement over that of the pristine Bi2O2Se prepared by solid-state reaction (SSR). This work opens a new gate for synergistically optimizing electron and phonon transport properties for Bi2O2Se-based thermo-electric materials.