Phosphor in the application package
In addition to be determine the package before the package structure, the need choose a good chip and phosphor. For the high color temperature of the cold white InGaN LED chips are usually used with the YAG: Ce yellow phosphor to obtain a low color temperature warm white LED based on the need to add this red phosphor or a UV-chip with the three color phosphors. LED chips and phosphor there is a match between the problem, only when the LED chip and phosphor emission peak excitation peak maximum overlap to maximize the efficiency of LED chips and phosphor.
Figure 1 for the InGaN chip and YAG: Ce phosphor's fluorescence spectrum, which left shaded with diagonal chip InGaN emission spectra, light gray shadow on the left of YAG: Ce in the excitation spectrum; the right side in the emission spectra under 460nm excitation . Can be seen from the figure, InGaN chip emission spectra and YAG: Ce excitation spectra overlap very well, thus making YAG: Ce is the most effective excitation conditions, so that YAG: Ce highest luminous efficiency. When the YAG: Ce excited the main peak to the left or right offset InGaN emission peak when the chips are significantly reduced degree of overlap between the two, resulting in packaged LED light efficiency decreased significantly.