Ho^3+-doped ZnO nano phosphor for low-threshold sharp red light emission at elevated temperatures

Abstract

As an approach to design efficient visible luminescent material at nano scale, Ho3+ ion-doped single-phase zinc oxide (ZnO) nano phosphor to obtain red emission suitable for LED/laser applications is reported. Ho3+-doped ZnO nanoparticles with various concentrations of Ho3+ have been prepared by a simple solgel synthesis technique. Under the excitation of 488 nm, the photoluminescence emission spectra of the nano phosphor exhibit an intense emission with multiple and well-resolved narrow splitting peaking in the range from 640 to 667 nm, which is identified as the emission from the Ho3+ ion, corresponding to F55→I58 transition with multiple splitting due to the ZnO crystal field. The required excitation threshold for these emissions is, surprisingly, as low as 33.8 kW/cm2, and the narrow line width (FWHM<2 nm) is found to be persistent even at higher temperatures. Such sharp emission from Ho3+:ZnO nanoparticles could be used for lasing applications.