CaAl12O19:Mn4+ 와 Y3Al5O12:Ce3+ 의 혼합 색변환층을 가지는 백색유기발광소자의 광학적 특성

Abstract

White organic light-emitting devices (WOLEDs) have attracted a great deal of interest due to their potential applications in full-color displays, backlights for liquid crystal displays, and solid-state lighting sources. Because the color mixing method for fabricating WOLEDs uses multiple emitters in a single WOLED, the structures of the WOLEDs are very complicated, and the manufacturing cost of the WOLEDs is very expensive. However, the color conversion method using several phosphor layers has several advantages of simple structure, low production cost, and high stability. Even though some studies on the fabrication of WOLEDs consisting of blue phosphorescentorganic light-emitting device (OLED) with a color conversion phosphor layer have been performed [1], their efficiencies, color coordinates, and color rendering index are insufficient to use backlight applications or general lighting sources. This paper reports data for the optical properties of WOLEDs fabricated utilizing mixed phosphor layers acting as a color conversion layer (CCL). Scanning electron microscopy(SEM) measurements were performed to clarify the size of the phosphor crystals were approximately between 0.1 and 3m.The WOLEDs were achieved due to the enhancement in the Commission Internationale de l’Eclairage (CIE) chromaticity coordinatesand Color Rendering Index(CRI) utilizing mixed CaAl12O19:Mn4+ and Y3Al5O12:Ce3+ phosphor layer, respectively.Electroluminescence (EL) and photoluminescence(PL) measurements on the blue phosphorescent OLEDs and the mixed CaAl12O19:Mn4+and Y3Al5O12:Ce3+phosphor layers were carried out to investigate the color stable of the phosphor layer. The EL spectra for WOLEDs fabricated utilizing a CCL with several different mixing ratios and thickness of the Y3Al5O12:Ce3+ phosphors and CaAl12O19:Mn4+showed that the emission peak was shifted from the blue light to the white light due to the CCL resulting from the precise combination of the blue, the red, and the yellow lights.