Raising the thermoelectric performance in Pb/In-codoped BiCuSeO by alleviating the contradiction between carrier mobility and lattice thermal conductivity

Owing to the unavoidable electron scattering, introducing phonon-scattering defects to suppress the phonon diffusion in thermoelectric materials will always deteriorate the carrier transport. Therefore, exploring new methods to counterpoise the contradiction between carrier transport and phonon scattering is urgently needed. Herein, present work highlights that Pb/In codoping on BiCuSeO can suppress the phonon propagation while preserving the carrier transport, which alleviates the contradiction between carrier mobility (μ) and lattice thermal conductivity (κl), and improves the thermoelectric performance in Pb/In-codoped BiCuSeO. Multi-scale phonon-scattering centers, such as point defects, dislocations, In2O3/Cu2Se nano-precipitates and phase/grain boundaries, were introduced to promote full-wavelength phonon scattering, which brought about much reduced κl and substantially low total thermal conductivity, and a minimum κl of 0.30 W m−1 K−1 was achieved in Bi0·91Pb0·06In0·03CuSeO at 873 K. More importantly, Pb/In codoping can compensate the increased density of state effective masses caused by Pb single-doping, which resulted in improved μ and the obvious increased μ/κl. In addition, the improved μ also led to considerably increased electrical conductivity and power factor. Finally, the maximum ZT of 1.23 at 873 K and a high ZTavg of 0.72 between 300 and 873 K are achieved in Bi0·93Pb0·06In0·01CuSeO, which is superior to both the pristine and Pb-single-doped counterparts. Our findings elucidate the importance of balancing the carrier transport and phonon scattering during defect modulation of the thermoelectric performance.