Visible emission comparison from both ZnO thin films and nanoarrays spin-coated with GO layers

GO is spin-coated on ZnO films and ZnO nanoarrays, respectively. Results indicate that a strong blue emission band and two shoulder peaks are observed in PL spectra of ZnO films and ZnO nanoarrays. As GO is spin-coated on the ZnO films, the blue emission intensity decreases. However, as GO is spin-coated on the ZnO nanoarrays, the blue emission is drastically increased and attains the maximum. We proposed that the effective work function of GO sheets will also be decreased sharply as they are spin-coated on ZnO nanoarrays. In this case, the Fermi levels of GO locate above the conduction band of ZnO. The electrons on the Fermi levels of GO can easily transported to the conduction band of ZnO resulting in the increase PL emission in the GO spin-coated ZnO nanoarrays.