High Thermoelectric Performance in Cu-Doped Bi 2 Te 2.7 Se 0.33 Due to Cl Doping and Multiscale AgBiSe 2 .

The thermoelectric performance of n-type Bi 2 Te 3 needs further enhancement to match that of its p-type Bi 2 Te 3 counterpart and should be considered for competitive applications. Combining Cu/Cl and multiscale additives (AgBiSe 2 ) presents a suitable route for such enhancement. This is evidence of the enhanced thermoelectric performance of Bi 1.995 Cu 0.005 Te 2.69 Se 0.33 Cl 0.03 . Moreover, by incorporating 0.65 wt % AgBiSe 2 (ABS) into Bi 1.995 Cu 0.005 Te 2.69 Se 0.33 Cl 0.03 , we further reduce its lattice thermal conductivity to ∼0.28 W m -1 K -1 at 353 K owing to the extra phonon scattering of multiscale ABS. Additionally, the Seebeck coefficient enhances (-183.89 μV K -1 at 353 K) owing to the matrix's reduced carrier concentration caused by ABS. As a result, we achieve a high ZT of ∼1.25 (at 353 K) and a high ZT ave of ∼1.12 at 300-433 K for Bi 1.995 Cu 0.005 Te 2.69 Se 0.33 Cl 0.03 + 0.65 wt % ABS. This work provides a promising strategy for enhancing the thermoelectric performance of n-type Bi 2 Te 3 through Cu/Cl doping and ABS incorporation.