THE STUDY OF CONVEX-DUAL-LAYER REMOTE PHOSPHOR GEOMETRY IN UPGRADING WLEDS COLOR RENDERING INDEX

The white-light light-emitting diode (LED) is a semiconductor light source that be created from one chip and one phosphor layer. Because of that simple structure, the color rendering index (CRI) is really poor. Therefore, a double layer of chip and double phosphorus test has been conducted, and thus the phosphorus proportions and densities in the silicone are constantly changed. In research, we use red phosphor Ca5B2SiO10:Eu3+ layer to place above the yellow phosphor one, and both of them have a convex design. Then, the experiments and measurements are carried out to figure out the effects of this red phosphor as well as the convex-double-layer remote phosphor design have on the LED’s performances. The measured results reveal that the light output is enhanced significantly with convex-dual-layer structure, compared to that of the one-layered design. Additionally, the Ca5B2SiO10:Eu3+ concentration makes the CRI and CQS present increase at around 6600K and 7700 K correlated color temperature (CCT). Yet, the lumen output shows a slight decline as this red phosphor concentration surpass 26% wt.. Through the experiments, it is found that a double layer of chip and double phosphorus is the best structure which could support the quality of CRI and luminous flux.