Enhanced thermoelectric properties of nanostructured n-type Bi2Te3 by suppressing Te vacancy through non-equilibrium fast reaction

As one promising low-temperature thermoelectric material, Bi2Te3 su ffers from high carrier concentrations beyond the optimal value contributed by excess Te vacancies. In this study, Te vacancies can be e ffectively suppressed in the n-type nanostructured Bi2Te3 via a non-equilibrium reaction induced by spark plasma sintering. The electron concentration has been greatly reduced from pristinely -1 x 10(20) to -7 x 10(19) cm(-3) , generating a decent power factor of 12.84 W cm(-1) K-2 at 320 K. Meanwhile, the decreased electronic thermal conductivity due to deteriorated electrical conductivity enables a very low thermal conductivity of 0.48 W m(-1) K-1 , which ultimately secures a promising peak figure of merit zT of -1.1 at 420 K and an outstanding average zT of similar to 1 from 320 to 470 K. Such a high performance is one of the cutting-edge values reported in binary n-type Bi2Te3 so far. Our study provides a new insight into manipulating intrinsic point defects in nanostructured Bi2Te3 thermoelectric materials for achieving higher zT .