Abstract
This study is aimed at obtaining a relatively higher-color-rendering index (CRI) white LED using a blue-emitting Sr4Al14O25:Eu2+ phosphor that could smooth out LED flicker. In order to study the luminescence of the phosphors in the LED package, a thin Sr4Al14O25:Eu2+ film and three-phosphors-containing (green YAG:Ce3+, red CASN:Eu2+, and indigo Sr4Al14O25:Eu2+) film were prepared using a spin coating method. Meanwhile, three-phosphors-LED package was fabricated using a dispensing process, whereby the chip surface was automatically leveled to form a film with the same composition and components as that of the three-phosphors-containing film. In order to study the reliability of Sr4Al14O25:Eu2+ phosphors in the resin, high-temperature and high-humidity test, Xenon lamp aging test, and thermal cycling test were carried out. The Sr4Al14O25:Eu2+ phosphors in the resin were also characterized through photoluminescence (PL) and PL decay curve analyses. The electroluminescence, correlated color temperature, and temperature-dependent PL of the three-phosphors-containing film were measured using an integrating sphere. The three-phosphors-containing film displayed high reliability and thermal stability. The blue LED was coated with a three-phosphors-containing film, which led to a correlated color temperature of ~ 4500 K and a high CRI (Ra > 90.2).This LED package had an afterglow light that could eliminate the observed LED flicker.
Published Version
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