High thermoelectric performance of BiCuSeO via minimizing the electronegativity difference in Bi–O layer

With the superiorities of low-cost, hypo-toxicity and intrinsic low thermal conductivity, layered oxyselenide BiCuSeO has been recently considered as a promising eco-friendly thermoelectric material. However, the relative low mobility (μ) postponed the further development of BiCuSeO especially in the heavily doped BiCuSeO. In this study, in order to achieve higher μ, the electronegativity difference was preferentially minimized in Bi–O layer by doping Te on O site into Bi_0.94Pb_0.06CuSeO. Deriving from the sharply improved μ, such a modification improved PF up to ∼9.6 μW cm⁻¹ K⁻² at 873 K when x = 0.01 and 0.03. Meanwhile, with the increased Te doping amount, the lattice thermal conductivity was suppressed to 0.35 W m⁻¹ K⁻¹ at 873 K, which should be mainly ascribed to the Cu₂Se nanodots. Finally, a high ZT value ∼1.4 at 873 K was obtained in Bi_0.94Pb_0.06CuSeO_0.97Te_0.03, which is 30% higher than Bi_0.94Pb_0.06CuSeO.