Enhanced thermoelectric performance of BiCuSeO via dual-doping in both Bi and Cu sites

We investigated the effects of dual-doping in both Bi and Cu sites on the thermoelectric performance of BiCuSeO. The electrical conductivity of Ba and Co dual-doped samples was largely enhanced compared to pristine BiCuSeO due to enhanced carrier concentration. Interestingly, Ba and Co dual-doped samples keep high Seebeck coefficient values as compared to Ba single doped sample, resulting in high power factor. While their thermal conductivities were significantly depressed by enhanced point defect scattering. These favorable factors lead to enhanced ZT of Ba and Co dual-doped samples as compared with Ba single doped sample, Co single doped sample and pristine BiCuSeO. ZT value of 0.082 at 350 K for Ba0.125Bi0.875Cu0.85Co0.15SeO was determined by nearly 32 times higher than that of pristine BiCuSeO. Moreover, this value is about five times higher than that of promising Ba0.125Bi0.875CuSeO. It reveals that dual-doping into both Cu and Bi sites is an effective way for optimizing thermoelectric properties of BiCuSeO. This study opens a new pathway for broadening and designing prospective thermoelectric materials.