![]() ![]() In order to solve the deficiency of intensity in the red spectral region, the red-emitting phosphor was added together with yellow-emitting phosphor and the CRI and correlated colour temperatures (CCT) of obtained white light sources were significantly improved. The first white LEDs were prepared by putting the yellow-emitting phosphor on the blue-emitting LED chip however, such approach yielded cool white light with low colour rendering index (CRI) thus unsuitable for indoor lighting. ![]() There are several ways to produce white light by employing a blue or near-UV-emitting LED chip. ![]() To date, white LEDs are the most efficient lighting source. During the past decade, phosphor-converted white light-emitting diodes (pc-WLEDs) were the research interest for many scientists and engineers because of their outstanding brightness and luminous efficiency, low power consumption, long device lifetime, reliability and eco-friendly characteristics compared to other lighting sources, for instance, incandescent and halogen light bulbs, and fluorescent lamps. ![]()
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