Luminescent properties of Tb(acac) 2 AA nanorods prepared by ultrasound irradiation

Rare earth organic complexes possess characteristic luminescent properties, such as extremely sharp emission bands, long lifetime and potential high internal quantum efficiency. The corresponding nano-materials have attracted extensive attention recently owing to the potential application for OLED and photovoltaic devices. In this report, ternary complex of rare earth Tb(acac)₂AA (acac= acetyl acetone, AA= acrylic acid ) uniform nanorods have been prepared by sonication. The properties of Tb(acac)₂AA nanorods were characterized by X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). It is interesting to observe that the nanoparticles with diameter of 300 nm are growing into the nanorods with size of 80×1200 nm (W×L) with the increasing of the power output. It can be explained that the cavitation effect was increased with the increasing power output and thus accelerated the growth of nanorods from nanometer-sized seed on the Tb(acac)₂AA nanoparticles. Furthermore, the size of the nanorods is much smaller than that of the bulk prepared by precipitation. The luminescent properties of Tb(acac)₂AA nanorods were studied in comparison with that of the bulk. The results indicated that the line shapes of corresponding luminescent spectras are similar, but the luminescent intensity of the nanorods is two times stronger than that of the bulk. It means that the nanorods have higher fluorescence quantum efficiency than the bulk. In addition, the fluorescence lifetime of the nanorods is obviously longer. In summary, sonication is an effective approach to prepare rare earth nanomaterial with high luminescence efficiency.