Optimizing thermoelectric power factor in magnetron sputtered Cu 2 Se thin films by varying substrate temperature and synergy of Cu/Se ratio

Copper selenide (Cu 2 Se) is recognized as a p-type thermoelectric (TE) semiconductor known for its ecofriendliness, abundance in the earth's crust, and cost-effectiveness. Current research on Cu 2 Se primarily centers around its exceptional TE capabilities in bulk materials. However, two-dimensional thin films hold distinct advantages in TE micro- and nano-device development and applications. In the present study, a series of Cu 2 Se thin films were deposited on a glass substrate by employing radio frequency magnetron sputtering deposition by varying the substrate temperatures (T s ) from 50 degrees C to 400 degrees C with an interval of 50 degrees C. The impact of T s role on the structural, microstructural, and electrical transport characteristics of Cu 2 Se thin films was investigated using the Grazing Incidence X-ray diffraction, High-Resolution transmission electron microscopy, Field Emission Scanning Electron Microscopy, and Seebeck analysis. The change in the T s increased grain growth as observed from microstructure studies and improved electrical and transport characteristics. Notably, films deposited at T s 350 degrees C exhibited a significant power factor of 16.8 mu W/cmK 2 at 450 degrees C, making them highly promising for TE applications.