Enhanced thermoelectric performance of La-doped BiCuSeO by tuning band structure

Bi1−xLaxCuSeO ceramic bulks have been prepared by the spark plasma sintering method. Our results indicate that La-doping can lead to an obvious change of the band structure evidenced by the absorption spectra and electric transportation behaviors (e.g., m* and Seebeck coefficient). The variation of band structure results in a great enhancement of carrier mobility caused by a decreased energy offset between the primary and secondary valence bands. A maximum ZT value of 0.74 can be obtained in 8% La-doped BiCuSeO sample at 923 K, which is 37% higher than that of the pure BiCuSeO bulk. Our results reveal that band engineering is an effective way to enhance the thermoelectric properties of BiCuSeO system.