Recent progress and future prospect of high-performance near-UV based white LEDs -from ECO lighting to medical application-

摘要

Near ultraviolet (n-UV) LED-based white light source (LS) can provide the excellent illuminant properties that show high-luminous efficacy (Le>80 lm/W) of radiation and high-color rendering index (CRI or Ra>99). Recent progress and future advantages of the n-UV white LED technology on the basis of our direct flip-chip bonding and stacked multi-layer structure methods will be described. Particularly, the fabrication process, and electrical and illuminant properties in the low-correlated color temperature (CCT or Tc～3452K) white LED with a high-luminous flux (～500 1m/PKG) are discussed, and its lighting and medical applications such as ecological street lighting and gastrointestinal digestive endoscope will be introduced. Furthermore, a color tunable white LS which is composed of multiphosphor conversion LEDs and its characterization are described. Differences on the quality of light between the n-UV white LED and the conventional blue-YAG white LED will be clarified.