以多層遠離螢光粉結構增強三波段白光發光二極體混光特性之研究

Enhanced Color Mixing Characteristics in Three-band White Light-Emitting Diode Using Multi-Layer Remote Phosphor Configuration

孫聖淵(Sheng-Yuan Sun)

指導教授 ： 劉容生

國立清華大學/電機資訊學院/光電工程研究所/碩士(2007年)

摘要

白光發光二極體的發光效率近年來已經超越了大部分的傳統光源，包括白熾燈以及螢光燈。然而，發光二極體如希望在未來普遍地用於固態照明的領域，在演色性與色彩穩定性等的混光特性上，白光發光二極體技術尚處於起步階段，有待加強。目前白光發光二極體最普遍的製作技術，是將發光二極體部分的光藉由螢光粉進行光轉換並進行混光。三波段白光發光二極體是提昇光轉換白光發光二極體演色性的一個有效方法之一，但是卻因為紅色波段的螢光取出效率不佳，所以在驅動電流改變的情況之下，呈現色彩穩定性不佳的問題。
本論文裡，我們在三波段白光發光二極體的封裝過程之中，藉由「多層遠離螢光粉」這種新的螢光粉封裝結構，有效的提升螢光粉光子的取出率，特別是在紅色螢光粉部分。在色溫3800K到5900K的白光範圍之中，實驗結果指出「多層遠離螢光粉」封裝結構的三波段白光發光二極體相較於傳統螢光粉封裝結構的三波段白光發光二極體，其發光效率約有95％的提升；在色彩穩定性方面，在驅動電流從50 mA到400 mA的操作下，「多層遠離螢光粉」封裝結構的三波段白光發光二極體其色差可降到0.006左右，則較傳統螢光粉封裝結構的三波段白光發光二極體所得到色差值約在0.03左右改善了五倍。

關鍵字

白光發光二極體 ； 高演色性 ； 遠離螢光粉結構

並列摘要

In this study, we have demonstrated that a Three-band LED in which the phosphorescence from red- and green- phosphors are mixed with a blue LED is an effective way to generate white color with a high color-rendering-index. However, in previous studies, it has been shown that the color performance is not stable at various drive currents in this type of structure. This problem is believed to result from a low extraction efficiency of the red phosphorescence.
In the present study, we have demonstrated the phosphorescence extraction can be improved effectively in a three-band white LED by using a new phosphor configuration, “Multi-Layer Remote Phosphor”. This novel phosphor configuration is found to be particularly useful for improving the extraction of red phosphorescence.
For the white light applications, our study further shows that an improvement of the luminous efficiency by about 95%, using a “Multi-Layer Remote Phosphor” configuration in three-band LEDs as compared with those found in a traditional “Proximate Phosphors” configuration. In these studies, the correlated color temperatures are maintained between 3800K and 5900K.
In the color stability, the color differences in a “Multi-Layer Remote Phosphor” configuration are measured to be about 0.006 when the operating currents varies from 50 mA to 400 mA.; a reduction by a factor of 5 as compared with that found in the traditional phosphor packaging configuration for a three-band white LEDs.

並列關鍵字

White LED ； High CRI ； Remote Phosphor

參考文獻

[3] S. Nakamura, T. Mukai, and M. Seno, Jpn. J. Appl. Phys., vol.30, L1998 (1991)

[4] S. Nakamura, M. Seno, and T. Mukai, Jpn. J. Appl. Phys., vol.32, L8 (1993)

[15] H. Chen, US Patent 5,962,971 (1999)

[17] N. Narendran, Y. Gu, J. P. Freyssinier, and Y. Zhu, Phys. Stat. Sol. (a), vol.202, no. 6, pp. R60-R62 (2005)

[23] D. Y. Kang, Enboa Wu, and Da-ming Wang, Appl. Phys. Lett. vol.89, 231102 (2006)