Design of a broadband cyan-emitting phosphor with robust thermal stability for high-power WLED application

Abstract

Due to the complicated production process and reabsorption problem, the development and application for white light-emitting diodes (WLEDs) are affected. A combination of cyan and red phosphors with near-ultraviolet (n-UV) LED chip has been proposed to solve these problems. Its key is developing cyan phosphor with broad emission band and excellent performances. In this work, we have developed a broadband cyan-emitting phosphor RbBa2(PO3)5: Eu2+ (RBP: Eu2+) by a solid-state method. The phase purity, crystal structure, luminescence properties and their relationship were investigated systematically. The RBP: Eu2+ phosphor can yield asymmetric broadband cyan emission upon 350 nm light excitation, which is ascribed to the occupation of Eu2+ for both the Ba1 and Ba2 sites. The measurement of temperature-dependent luminescence implies that the phosphor remains 89.5% of the initial value at 150 °C, which is much better than the commercial Ba2SiO4: Eu2+ phosphor. Furthermore, a WLED device has been obtained by composing the RBP: 0.01Eu2+ and CaAlSiN3: Eu2+ phosphors with a 365 nm LED chip. The emitted white light can show fabulous performances with the color coordinates of (0.3792, 0.3359), correlated color temperature of 3841 K and CRI of 90.8. The results suggest the RBP: Eu2+ phosphor to be a promising candidate for high-power WLEDs.