CdO: A promising flexible and transparent thermoelectric power generator

Transparent thermoelectric films have attracted much interest due to the unusual coexistence of thermoelectric and optical transparency in a single device. Moreover, many devices, such as implantable electronic devices, chip sensors, localized refrigeration devices, are intrinsically of irregular shapes. Therefore, exploration for a flexible and transparent thermoelectric power generator (F-TTEG) is on the rise. In this study, we develop n-type transparent CdO films on the polyimide (PI) substrate, which exhibit outstanding flexibility, maintaining 90% and 99% of their original electrical conductivity and transmittance after 500 bending cycles around a 11-mm diameter rod. The films also demonstrate a high power factor of ∼ 1.3 μW cm−1 K−2 at room temperature. A thermoelectric prototype consisting of 8-leg of the CdO film generates a voltage of 15.2 mV and a maximum power density of 5.48 W m−2 at a temperature difference of 85 K. This work suggests that CdO films offer promising prospect for the development of high performance F-TTEG devices.