Improved CCT uniformity of white LED using remote phosphor with patterned sapphire substrate.

The light distribution of a light-emitting diode (LED), using remote phosphor with a patterned sapphire substrate, is evaluated in this study. Three kinds of substrates of the remote phosphors, including planar sapphire (PS), partially patterned sapphire (PPS), and fully patterned sapphire (FPS) are prepared. The LED with the remote phosphor of FPS delivers much better uniformity of the correlated color temperature (CCT) in a far-field pattern than the CCT obtained in the cases of PS and PPS. The results are majorly attributed to the improvement in the scattering ability of the blue light in the FPS; thereby increasing the excitation of the phosphor particles in comparison to the ability of the device assembled with the remote phosphor of PS or PPS.