Doping effects on the thermoelectric properties of Cu-intercalated Bi2Te2.7Se0.3

•Polycrystalline bulks of n-type Bi2Te2.7Se0.3-based thermoelectric materials were fabricated by spark plasma sintering.•The reproducibility of Bi2Te2.7Se0.3 was significantly improved by Cu-intercalation.•We can control the electronic and thermal transport properties by compositional tuning approach.•Thermoelectric performance was enhanced by Cu-intercalation and Al-doping.

We herein report an enhancement of the thermoelectric performance of spark plasma sintered polycrystalline n-type Bi2Te2.7Se0.3 by the intercalation of Cu and the doping of Al on Bi-sites. Through the intercalation of a small amount of Cu (0.008), the reproducibility could be significantly improved, with ZT was enhanced from 0.64 to 0.73 at 300 K due to the reduced lattice thermal conductivity benefiting from intensified point-defect phonon scattering. We also found that Al is an effective doping element for power factor enhancement and for reducing the lattice thermal conductivity of Cu-intercalated Bi2Te2.7Se0.3. With these synergetic effects, an enhanced ZT values of 0.78 at 300 K and 0.81 at 360 K were obtained in 1 at% Al-doped Cu0.008Bi2Te2.7Se0.3 (Cu0.008Bi1.98Al0.02Te2.7Se0.3).

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