Optical-Thermoelectric Trade-off in Mg-Doped CuCrO2 Films via Crystal Orientation Control with an Oxygen-Rich Seed Layer

Mg-doped CuCrO 2 delafossite, a naturally p -type conducting oxide, shows promise for applications in thin film thermoelectric and optoelectronic devices. However, the correlation between the thermoelectric, crystalline, and optical properties remains insufficiently understood. Herein, we explored the impact of an oxygen-rich seed layer on the crystal orientation as well as on the optical and thermoelectric properties of Mg-doped CuCrO 2 films. The seed layer promoted a dominant (012) crystal orientation, which enhanced optical absorption in the visible spectrum from 38% to approximately 60% compared to films without the seed layer. While this orientation improved optical properties, it suppressed the (110) orientation, which is critical for high electrical conductivity in CuCrO 2, thereby negatively affecting thermoelectric efficiency. Specifically, the power factor decreased from 50 to 30 μW/m·K 2 with the addition of the seed layer. Ultimately, the inclusion of a seed layer provides a means to control crystal orientation and improve optical absorption, thereby increasing the utility of Mg-doped CuCrO 2 films for visible-light optoelectronic devices.