Silver Copper Oxide: A p-Type Transparent Conductive Oxide?

In this study, we report the room-temperature synthesis, detailed characterization, and first-principles modeling of monoclinic AgCuO2, a p-type transparent conducting oxide (TCO) candidate. AgCuO2 was synthesized via an oxidative coprecipitation method using Ag(I) and Cu(II) precursors in the presence of potassium persulfate as an oxidizing agent. Structural and morphological analyses, including powder X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy, and atomic force microscopy, confirm the formation of a highly crystalline crednerite-type phase with minimal CuO impurity. Optical spectroscopy, combined with Kelvin probe, surface photovoltage spectroscopy, and UV photoemission measurements, reveals a direct optical bandgap of ∼2.5 eV and a Fermi level close to the valence band maximum, indicative of p-type semiconductor behavior. Importantly, the ambiguity of whether AgCuO2 is metallic or a semiconductor was resolved in the present study both by experiment and theory. Complementary electrochemical analyses demonstrated quasi-reversible redox activity and stability of the AgCuO2 surface, while conductivity measurements provided insight into the charge transport mechanism. Density functional theory (DFT + U) calculations corroborated the experimental findings, predicting a layered structure with Cu in a +3 oxidation state and revealing that Ag vacancy defects could enhance electrical conductivity without compromising optical transparency. This integrated experimental and computational approach establishes AgCuO2 as an electronically conductive, optically transparent, and electrochemically robust TCO candidate with potential for optoelectronic, photoelectrochemical, or solar photovoltaic applications.