Realization of n-type and enhanced thermoelectric performance of p-type BiCuSeO by controlled iron incorporation

Layered oxyselenide BiCuSeO has recently attracted much attention as a promising p-type eco-friendly thermoelectric material. The future development of BiCuSeO-based thermoelectric modules requires compatible p- and n-type materials. In the present work, we show that n-type BiCuSeO can be obtained below 500 K by substituting Fe for Cu in pristine BiCuSeO. Besides, co-substitution of Fe for Cu in p-type doped Bi_0.94Pb_0.06CuSeO can enhance both S and σ, which originates from high hole mobility with relatively high hole concentration, improving the power factor of BiCuSeO remarkably to above 0.9 mW m^-1 K^-2 in the whole temperature range while maintaining a low thermal conductivity. A high ZT_peak of around 1.5 at 873 K with an average ZT of around 1 between 310 K and 873 K was reproducibly obtained for p-type Bi_0.94Pb_0.06Cu_0.99Fe_0.01SeO. This new substitution opens a new direction that could pave the way for practical application of combined p- and n-type BiCuSeO in thermoelectric modules.