New phosphors Eu2+ and Ce3+ doped Sr4-x(Si,Al)19+x(N,O)29+x for white LED applications (Conference Presentation)

Abstract

Light-emitting diodes (LEDs) have been steadily consolidating their share in the lighting and display market. Phosphor-converted (pc) white LED becomes the preferred way to generate white light especially for general lighting, as it is much cheaper and simpler than RGB system. Phosphors are essential to high color quality and luminous efficacy. However, the number of commercially available phosphors is very limited. Therefore, developing new phosphors suitable for various white LED applications is very important. Recently, our group developed the single-particle-diagnosis approach [1-2] to discover new phosphors, with which a tiny luminescent microcrystalline particle down to 5-10 μm can be selected from powder mixtures. In this work, we report a new green emitting Sr-sialon:Eu phosphor discovered by this approach. The crystal structure was solved and refined from single crystal X-ray diffraction data. Sr-sialon:Eu crystallizes in the trigonal space group P3m1 (no. 156) with a = b = 12.1054 A, c = 4.8805 A and Z = 1, and consists of a network of corner sharing (Si,Al)(N,O)4 tetrahedra. Upon doping with Eu2+, the emission band can be tuned from 487 nm to 541 nm with fwhm = 96-124 nm. Ce3+ doped Sr-sialon phosphor shows strong blue emission around 435 nm with a fwhm ≈ 90 nm after 355 nm light excitation. The blue luminescence exhibits a small thermal quenching behavior at high temperature. These performances show that the new Eu2+ and Ce3+ doped Sr-sialon phosphors are promising for white LED applications. [1] N. Hirosaki, T. Takeda, S. Funahashi and R.-J. Xie, Chemistry of Materials, 2014, 26, 4280-4288. [2] T. Takeda, N. Hirosaki, S. Funahashi and R.-J. Xie , Materials Discovery, 2015, 1, 29-37.