Optical Study of Phosphor Converted Light Emitting Diodes with Given Correlated Color Temperatures

A given corelated color temperature (CCT) for phosphor converted light emitting diodes (pcLED) can be achieved by different phosphor gel concentrations or volumes. Though the CCT is the same, other optic performances may be distinguishable. In this paper, the variety of lumen efficiency and angular color unity (ACU) for LED with given CCT were investigated by Monte Carlo ray-tracing simulations. It is found that though the CCT is the same, the lumen efficiency and the ACU change distinctly with different phosphor gel concentration and volume. For the CCT of 4200 K, 4700 K, and 6000 K, the lumen efficiencies have a variety of 4.1%, 5.9%, and 4.0%, respectively, while the ACUs have a change of 7.4%, 20.1%, and 30.5%, respectively. It is also found that lumen efficiency increases with the increment of the volume of phosphor gel for the same CCT.