| 초록 |
Thermoelectric (TE) technology has been regarded as a promising renewable energy source without moving parts and greenhouse gas emissions. However, energy conversion efficiency of TE materials has been still low, which results in lagged commercial application. Bismuth telluride (Bi2Te3) has been highlighted with decent electrical transport properties and corresponding high TE figure of merit (ZT). Nevertheless, since many strategies reducing thermal conductivity of Bi2Te3 also deteriorate the electrical transport properties, the progress in n-type Bi2Te3-based material has been delayed compared that of the p-type system. Here we present n-type Bi2Te3-based material via introducing excess alkali metal cations. Alkali metal cations induce many types of point defects inside Bi2Te3 matrix, resulting in inducing lattice distortion. These might extremely scatter acoustic phonons and reduce lattice thermal conductivity of excess K doped-Bi2Te2.7Se0.3 system down to ~0.2 W m-1 K-1 at 400 K. |
