Realizing BiCuSeO-based thermoelectric device for ultrahigh carrier mobility through texturation

The thermoelectric conversion technology, as a promising renewable energy technology, enables direct and efficient conversion between electricity and heat. In the past ten years, there has been an increasing curiosity towards oxide thermoelectric materials due to their environmentally friendly nature, low cost, and excellent thermal and chemical stability. However, the intrinsic low carrier mobility of BiCuSeO limits its potential to be a high-performance thermoelectric material. Herein, we propose a dynamic sintering approach to enhance carrier mobility of BiCuSeO. As a result, carrier mobility at room temperature of three-step textured Bi0.94Pb0.06Cu0.97Se1.05O0.95 reaches an ultrahigh value of 13.1 cm2 V-1 s-1, which is the highest reported in the conventional doping of BiCuSeO system. Based on the ultrahigh carrier mobility, the power factor of three-step textured Bi0.94Pb0.06Cu0.97Se1.05O0.95 sample could reached 20 μV cm-1 K-2 near room temperature, and the average power factor of 300-923 K could reach 18.0 μV cm-1 K-2, effectively optimizing the electrical performance throughout the entire test temperature span. As a result, we successfully attain a ZT of ~ 1.5 at 923 K and a ZTave of 0.89 within the temperature span of 300-923 K for three-step textured Bi0.94Pb0.06Cu0.97Se1.05O0.95 sample. Based on the outstanding performance, we have successfully built a 7-pair thermoelectric device based on three-step textured Bi0.94Pb0.06Cu0.97Se1.05O0.95 paired with the N-type two-step textured Bi2Te2.7Se0.3Cu0.01, which is the first BiCuSeO-based thermoelectric device. The thermoelectric device, exhibits a maximum conversion efficiency of 2.8% at the temperature difference 215 K and simultaneously achieves a cooling temperature difference of 23.5 K with the hot end at 286 K. This work indicates that texturation is an effective approach for enhancing the carrier mobility of oxide TE materials. Besides, BiCuSeO oxyselenide is promising for pollution-free and cost-effective thermoelectric devices of power generation and cooling, thereby offering potential implications for sustainable energy solutions.