Phosphors and white LED packaging

Abstract

Both phosphors and the LED packaging play a crucial role in optical properties of white LEDs. The selection criteria of the host lattice, activator ions as well as phosphors utilized in white LEDs are firstly discussed, followed by the overview of the technologically important phosphors, including yttrium aluminum garnets, alkaline earth orthosilicates, alkaline earth sulfides/thiogallets, and (oxo)nitridosilicates (i.e., nitrides). Typically, (oxo)nitridosilicate phosphors are highlighted and introduced in this chapter as they have significantly red-shifted photoluminescence spectra, abundant emission colors and high reliability. Then, the LED packaging configurations, such as “phosphor-in-cup,” “remote-phosphor,” and quantum dot (QD) white LEDs, are discussed in terms of their luminous efficacy, color rendering index, and color temperature. Finally, some issues on phosphors (materials searching, color tuning, particle size, and geometry) and white LEDs (packaging configurations and reliability assessments) are addressed.