利用奈米粒子及雙層結構製作高發光效率與高品質之分離式螢光粉之白光發光二極體

Abstract

於本篇論文中，我們使用具有環保且無化學汙染之脈衝式噴塗技術製作分離式螢光粉之白光發光二極體。分離式螢光粉結構之優點為減少背向散射光線損耗與高發光效率，然而，卻會產生嚴重之黃圈現象。於本論文中，主要著重於提升分離式螢光粉白光發光二極體之發光效率與解決變角度色溫表現不均勻之問題。 首先，於雙層結構分離式螢光粉之白光發光二極體研究中，相較傳統分離式螢光粉，我們置入一層低折射率介質於螢光粉內部，此結構有效提升螢光粉之利用率，進而改善發光效率與提供更佳之顏色穩定性，透過電場模擬結果，光線可有效集中於螢光粉層內，並且增加螢光粉吸收之機會，由光譜圖得知黃光波段有明顯之增強。 再者，由於分離式螢光粉之白光發光二極體實際運用於照明時會產生變角度色溫差異過大之現象，我們利用噴塗方式結合高散射能力之奈米粒子氧化鋯沉積於白光發光二極體表面，其優越之散射特性可有效改變藍光之出光路徑，大幅改善各角度下之色溫分佈，並解決照明產生之黃圈現象。

In this thesis, we successfully fabricate the remote phosphor package in White light-emitting diodes (WLEDs) by pulsed spray coating (PSC) method. The advantages of the remote phosphor packages could effectively reduce the backscattering and exhibit the higher luminous efficiency. However, the yellow ring effect is the serious problem in the remote phosphor packages. Therefore, we developed the two efficient packaging configurations including dual-layer remote phosphor package and ZrO2-type remote phosphor package to obtain the high luminous efficiency and high quality WLEDs First, the dual-layer phosphor structure is demonstrated to enhance the light output in the remote phosphor structure. With inserting the thin silicone layer in the phosphor layer, the utilization of blue light could be enhanced, which leads to the higher luminous flux and provides a color stability of light. Furthermore, the simulation results indicated that more blue rays efficiently trapped in the embedding layer and the absorption probability of phosphor could be enhanced. Meanwhile, the results indicated that the dual-layer structure has the higher intensity in blue and yellow components than the conventional remote phosphor package. Next, the effect of the inhomogeneous angular-dependent CCT in the remote phosphor package has been regarded as the urgent issue to overcome. In this study, the PSC method is employed to spray the ZrO2 nano-particales onto the surface of the conventional remote phosphor structure and Luxeon package in WLEDs to improve the uniformity of CCT distribution. The superior scattering capability of ZrO2 nano-particles not only improve the CCT distribution but also solve the yellow effect.