Doping and band engineering by vanadium to enhance the thermoelectric performance in n-type Cu0.008Bi2Te2.7Se0.3

Polycrystalline bulks of Sc-, Ti-, and V-doped n-type Cu0.008Bi2Te2.7Se0.3 were prepared by melt solidification and spark plasma sintering, and their thermoelectric transport properties were investigated. The lattice thermal conductivity of Cu0.008Bi2Te2.7Se0.3 was slightly reduced by intensified point defect phonon scattering by the substitution of Sc, Ti, and V atoms on the Bi-site. On the other hand, the power factor of Cu0.008Bi2Te2.7Se0.3 was significantly enhanced by doping of V. Through the experimental and theoretical considerations, it was found that the enhanced power factor by V doping is originated from the increased density of states (DOS) effective mass by modified DOS near at Fermi level. Resultantly, an enhanced zT of 0.85 at 300 K was obtained in 1 at% V-doped Cu0.008Bi2Te2.7Se0.3 (Cu0.008Bi1.98V0.02Te2.7Se0.3).