Fabrication of copper-niobium-oxygen complexes as a photocathode for p-type dye-sensitized solar cell

Thin film of copper niobate ternary oxide with various compositions was fabricated by pulsed laser deposition technique. Formation of a single phase of monoclinic CuNbO3, monoclinic CuNb3O8 (Cu[I]), and triclinic Cu3Nb2O8 (Cu[II]) thin films was confirmed from the X-ray diffraction and selected area energy diffraction analysis. Field emission scanning electron microscopy and high-resolution tunneling electron microscope show CuNbO3 and CuNb3O8 system that exhibits polyhedron and triangular structure, respectively, while Cu3Nb2O8 system shows layered structure formation. The linear spectrum shows a minimal variation in bandgap concerning to the change in elemental composition and position of the copper and niobium atom. Cyclic voltammetry studies endorse that the prepared films are highly adhesive even after 100 cycles. With various compositions of copper niobate thin films as photocathode, N719 sensitized p-dye-sensitized solar cells (p-DSSCs) were fabricated for the first time. Monoclinic CuNbO3 system offers outstanding photovoltaic performance of 2.19% and thus can be used as an alternative for well-known NiO p-DSSC. Advantages of copper-niobium-oxygen systems open a new route of photocathodic materials for p-DSSC and tandem solar cells.