Synergistically Optimizing Electrical and Thermal Transport Properties of BiCuSeO via a Dual-Doping Approach

The layered oxyselenide BiCuSeO system is known as one of the high-performance thermoelectric materials with intrinsically low thermal conductivity. By employing atomic, nano-to mesoscale structural optimizations, low thermal conductivity coupled with enhanced electrical transport properties can be readily achieved. Upon partial substitution of Bi3+ by Ca2+ and Pb2+, the thermal conductivity can be reduced to as low as 0.5 W m(-1) K-1 at 873 K through dual-atomic point-defect scattering, while a high power factor of approximate to 1 x 10(-3) W cm(-1) K-2 is realized over a broad temperature range from 300 to 873 K. The synergistically optimized power factor and intrinsically low thermal conductivity result in a high ZT value of approximate to 1.5 at 873 K for Bi0.88Ca0.06Pb0.06CuSeO, a promising candidate for high-temperature thermoelectric applications. It is envisioned that the all-scale structural optimization is critical for optimizing the thermoelectricity of quaternary compounds.