Enhancement of light extraction efficiency with different molar amount of europium in TiO2:Eu3+ for WLEDs

To evaluate of light extraction efficiency and structural properties, Eu3+ doped TiO2 sphere were prepared by means of solvothermal reaction method. The influence of Eu3+ concentration on the size and surface morphology of TiO2 spheres were examined by taking the scanning electron microscope and transmission electron microscope images. When the Eu3+ ion was introduced in anatase phase, the intense red emission of 612.5 nm was observed under the excitation at 392.5 nm. The emission intensity increased with increasing the concentration of Eu3+ ions. Moreover, the diffused reflectance spectra of Eu3+ doped TiO2 spheres exhibited higher reflectivity by high concentration of Eu3+ ions. When the blue LED chip is coated with a combination 10 mol% Eu3+ doped TiO2 spheres and commercial Y3Al5O12:Ce3+ phosphor, a pleasant WLED with a high intensity, a CRI of 62 and a CCT of 4938 k, which are enhanced light extraction efficiency, is achieved.