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We have demonstrated that a phosphor conversion (PC) white light-emitting diode (LED) light source composed of multi-layered (ML) red, green, and blue (RGB) phosphors with a near-ultraviolet (n-UV) LED as an excitation source shows excellent color rendering, luminous efficacy, and luminous flux. The ML-phosphor structure consists of vertically stacked layers and could significantly reduce cascade excitation loss compared with a mixed RGB PC white LED. A high luminous efficacy of 82 lm/W with a high color-rendering index (CRI) of over 90 was achieved using a ML-RGB PC white LED. The ML-RGB structure also enables a white LED with an ultrahigh CRI of 99 and a high luminous efficacy comparable to that of a high CRI fluorescent lamp. We have also fabricated a high-power ML-PC white LED excited by an n-UV LED. In one package, a high luminous flux of 61 lm at a high CRI of 94 was obtained.

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