Plasmon-enhanced ZnO nanorod/Au NPs/Cu₂O structure solar cells: Effects and limitations

Abstract

Cu-based compounds can be a good candidate for a low cost solar cell material. In particular, Cu (x) O (x : 1-2) has a good visible light absorbing bandgap at 1-2 eV. As for using nanostructures in solar cell applications, metal nanoparticle-induced localized plasmon resonance is a promising way to increase light absorbance, which can help improve the efficiency of solar cells. We fabricated ZnO nanorod/Au nanoparticles/Cu₂O nanostructures to study their solar cell performance. ZnO nanorods and Cu₂O layer were synthesized by the electrodeposition method. Size-controlled Au nanoparticles were deposited using E-beam evaporator for localized surface plasmon resonance (LSPR) effect. By inserting Au plasmon nanoparticles and annealing Au NPs in solar cells, we could tune the maximum incident photon-to-current efficiency wavelength. However, the potential well formed by Au NP at the ZnO/Cu₂O junction leads to charge-trapping, based on the constructed electronic band analysis. LSPR-induced hot carrier generation is proposed to promote carrier transport further in the presence of Au NPs.