The Cr-doping effect on white light emitting properties of Ce:YAG phosphor ceramics

The Cr/Ce-doped YAG transparent ceramic was fabricated by the solid-state reaction in vacuum. The Cr/Ce-doped YAG ceramic phosphor effectively complement the red spectral component and improve the color rendering performance when excited by blue light that is due to the effective energy transfer between Cr3+ ion and Ce3+ ion. However, the energy transfer from Ce3+ to Cr3+ ion leads to energy loss and therefore the luminous efficacy of the WLED which is composed of blue LED chip and the Cr/Ce-doped YAG ceramic phosphor decreases. The composite phase structure of ceramic phosphor is designed for improving the extraction efficacy and increasing the luminous efficacy by breaking the total internal reflection (TIR) at the interface between air and ceramic.