Alkali Metals Doped Cu_0.94A_0.06O (A = Li, Na and K) Thin Films: Facile Synthesis, Structural, Optical and Thermoelectric Properties

The lack of successful p-type semiconductor oxides delays the future implementation of metal oxide semiconductor photovoltaic and thermoelectric devices. In the group semiconducting compounds, copper oxides present promising electrical, optical and manufacturing features that establish this family of materials suitable for p-type semiconductor applications. In this work, we focused on the growth of alkali doped CuO thin films, aiming for enhancements of their structural, optical, electrical and thermoelectric response. During this study, we highlight the effect of copper oxide doped with alkali ions (Li⁺, Na⁺, K⁺) prepared by the sol-gel technique and deposited on glass substrates. The effective substitution of the alkali elements into CuO lattice is analyzed by physical characterization i.e. X-ray diffraction, the spectra matched well with the monoclinic phase. Ultraviolet-visible spectroscopy showed that the band gap energy tends to increase with alkali doping and achieves a maximal value with (Li⁺) doping. Among the alkali ions (Li⁺) was the most effective to enhance electrical conductivity. Conductivity type showed by thermoelectric/hot prop confirmed the P-type conductivity. The maximum power factor PF was (9.776 × 10^–10 W m^–1 K^–2) for Li doped CuO. The present work is worth significant for thermoelectric devices.