Localized surface plasmon resonance of Cu-doped ZnO nanostructures and the material’s integration in dye sensitized solar cells (DSSCs) enabling high open-circuit potentials

Abstract

Herein, we report one step co-precipitation method of synthesis of ZnO and Cu-doped ZnO nanostructures with distinct amount (1, 3 and 5 mol %) of copper. All the synthesized samples are characterized by X-ray powder diffraction, Field emission scanning and Transmission emission microscopy. The optical properties of the samples were evaluated by UV-visible spectroscopy and photoluminescence studies. The presence of Cu atoms in the ZnO matrix enhances a broad spectral absorption upto near-IR region. Suppressed E2high phonon modes are observed in Cu-doped samples through Raman scattering measurements, which furnishes evidence for effective Cu-doping in ZnO crystal lattice. Un-doped and Cu-doped ZnO samples were integrated in Dye sensitized solar cells (DSSCs) as photoanode materials. The device performance and interface charge transfer properties were evaluated through photocurrentdensity-photovoltage measurements and electrochemical impedance spectroscopy respectively. It is noted that the incorporation of Cu2+ into the hexagonal wurtzite structure of ZnO considerably elevates the Fermi levels towards the conduction band edge which is the root cause for high open-circuit potentials of DSSCs integrated with Cu-doped ZnO photoanodes.