利用可撓式螢光粉膜片與混合式螢光粉結構製作高效率白光發光二極體

Abstract

近年來，白光發光二極體由於體積小、效率高與高穩定性等優點，具有極佳潛力取代傳統照明，並且已成為人類社會中相當重要的光源。因此，於本論文中，我們針對白光發光二極體中的螢光粉塗佈結構進行改良，透過提昇封裝體內部藍光的利用率，進一步改善白光發光二極體之發光效率，並且應用於大面積與高功率之照明系統。 第一部分為發展製程簡便與低成本的可撓式螢光粉膜片製成分離式螢光粉結構，藉由增加藍光的利用率，以提升整體白光發光效率。由實驗結果證明，此種簡易製程的螢光粉結構相較於傳統點膠製程，無論在冷白或暖白光源之應用上皆擁有較佳發光效率，最後在可靠度實驗中證實此種結構擁有較佳強度維持率與較低色溫偏差。除此之外，我們亦將可撓式螢光粉膜片應用於覆晶發光二極體，並且獲得更高效率之光源，相當適合未來更高功率之發光源應用。 第二部份，我們利用微奈米粒子脈衝噴塗技術結合敷型塗佈與分離式塗佈發展混合式螢光粉結構，在定量的條件下藉由調整兩層螢光粉的相對厚度，並取得到最佳化條件，其發光效率相較傳統敷型、分離型分別有約11.7%與5.9 %的提昇。藉由TFCalc模擬電場分析證實，此結構能有效將藍光部份侷限於雙層螢光粉結構內部當中，並有效率地激發黃色螢光粉所致。此外，由變角度分析結果證實此種結構能夠有效將變角度色溫差異維持在較佳的範圍內，成功改善分離式螢光粉結構色品質之議題。

Recently, white Light-emitting diodes (LEDs) have been regarded as the next generation of environment lighting sources because of its small size, high efficiency, and longer lifetime, especially in solid-state lighting (SSL). In this thesis, we developed the new phosphor coating structure to improve the luminous efficiency of white LED by enhancing the utilization of blue ray in the LED package, which has the great potential to use in the large area and high power lighting application. First of all, the flexible phosphor film structure by spin coating method for both cold and warm white LED is demonstrated. The experiment result shows that the flexible phosphor film structure yielded higher lumen efficiency intensity than a conventional dispense structure due to the utilization of blue light. In addition, the flexible phosphor film is also combined with flip chip package to produce white light and proved that such techniques can produce highly efficient lighting source. Secondly, we demonstrated a novel “hybrid” phosphor structure for white LED. The hybrid phosphor structure produces more efficient luminosity than the conventional remote and conformal phosphor structures. Using a TFCalc32 simulation, the electric intensity of the hybrid phosphor structure was calculated for various thicknesses, and the enhanced use of blue rays was verified. Moreover, the hybrid phosphor structure shows more uniform angular correlated color temperature (CCT) by using ZrO2-dispensed and texture PDMS film-attached methods, respectively. Therefore, the hybrid structure provides an appropriate solution for the white LEDs.