Synergetic Tuning of the Electrical and Thermal Transport Properties via Pb/Ag Dual Doping in BiCuSeO

The influence of Pb/Ag dual doping on the thermoelectric performance of BiCuSeO was investigated. It reveals that the electrical conductivity can be obviously improved owing to the increased carrier concentration mostly caused by the divalent Pb 2+ doping at trivalent Bi 3+ . The electrical conductivity improves from 7.29 S/cm for BiCuSeO to 397.40 S/cm for Pb 0.06 Bi 0.94 Cu 0.94 Ag 0.06 SeO and Pb 0.06 Bi 0.94 CuSeO at 327 K. Combined with the moderate Seebeck coefficient (>120 μV/K) due to the large effective mass, a large power factor with 834 μW/mK 2 is achieved. Meanwhile, the lattice thermal conductivity is visibly decreased, mainly benefiting from the substitution of Ag + at the Cu + site since the phonon scattering can be enhanced by mass fluctuation and strain fluctuation between the two elements. Thus, the total thermal conductivity is suppressed effectively compared with the Ag-free sample Pb 0.06 Bi 0.94 CuSeO. Finally, a maximum ZT value with nearly 1.0 has been obtained for Pb 0.06 Bi 0.94 Cu 0.94 Ag 0.06 SeO at 873 K, which is ∼64% and ∼47% larger than those of the pristine sample BiCuSeO and Ag-free sample Pb 0.06 Bi 0.94 CuSeO. Additionally, the ZT is also larger than the maximum value for the reported Pb-free samples BiCu 0.94 Ag 0.06 SeO and Bi 0.92 Ag 0.08 CuSeO, suggesting Pb and Ag are effective codopants of BiCuSeO to synergetically tune its electrical and thermal transport properties.