Effects of Phosphor's Location on LED Packaging Performance

High power LED packaging is crucial for the development of solid state lighting. Different optical structures with various states of phosphor will greatly influence the packaging performance such as luminous efficiency, quality of white light and color uniformity. Through the analysis of five different optical structures, it is found that the location of phosphor layer has low impact on the light extraction efficiency, except structures in which phosphor is directly coated on the chip. However, the correlated color temperature (CCT) and luminous efficacy greatly depends on the structure and location of phosphor layer. The light extraction efficiency and CCT of curved phosphor layer is normally higher than those of plane shape. However, considering the variations of luminous efficacy, it's suggested that the structure with plane and remote phosphor may be suitable for obtaining high performance LED modules.