Efficient dual mode emission in Ce/Yb/Er doped yttrium aluminium gallium garnet for led device and optical thermometry.

By utilizing the effective energy transfer from Ce to Yb, Er and from Yb to Er authors have achieved dual mode emission in YAlGaO activated with Ce/Yb/Er ions. Surface morphological and elemental compositions of the prepared samples have been examined using field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDS) analysis, respectively. The chemical state of the dopant ions is confirmed by the X-ray photoelectron spectroscopy (XPS). On excitation with 438 nm the prepared material has shown broad visible emission band around 511 nm due to the electronic transition of Ce ion. In addition to this sample has also shown NIR emission bands centered around 1024 nm and 1480 nm from Yb and Er ions, respectively. The emission band at 1024 nm could be due to the quantum cutting (QC) process. Furthermore, up-conversion (UC) emission against temperature and laser power variations is studied on 980 nm excitation wavelength. The prepared sample is used to fabricate visible and NIR LED devices by coating of sample on blue LED chip. Along with this demonstration, optical thermometry ability of the material is studied using emission intensity ratio of two emitting levels. Studies suggest that the prepared material could be useful as dual mode emitting phosphor and LED.