Fig. 1. SEM images of (a) ZnO and (b) ZnO:Eu(3%) microrods; (c) XRD spectra and standard card data of ZnO microrods before and after doping (Inset is a partial magnification of the diffraction peaks)

Fig. 2. (a) PL spectra of a single ZnO microrod before and after doping under 325-nm excitation (the blue dot line is the peak fitting for ZnO, and the red dot line is the peak fitting for ZnO:Eu-3%); (b) PL spectra of a single ZnO:Eu microrod with different doping concentrations at 532-nm excitation (Inset is the concentration quenching curve)

Fig. 3. Ultraviolet-visible absorption spectra of ZnO and ZnO:Eu microrods with different doping concentrations

Fig. 4. Time-resolved PL spectra of ZnO and ZnO:Eu microrods with different doping concentrations. The illustration is the attenuation constant calculated from the time-resolved PL of ZnO and ZnO:Eu microrods

Fig. 5. (a) Experimental setup for measuring the polarization-sensitive luminescence; (b), (c) and (d) The luminescence intensities of ZnO:Eu microrods with different doping concentrations vary with the angle of polarized light under of 532-nm excitation