液態高演色性量子點螢光粉與可撓式照明之發光元件模組之研究

Study of uniform white light LED source on a flexible substrate applied in wearable device and high performance LQD in glass package device

佘慶威(Sher, Chin Wei)

指導教授 ： 傅建中 ； 郭浩中

國立清華大學/工學院/動力機械工程學系/博士(2015年)

https://doi.org/10.6843/NTHU.2015.00505

摘要

傳統的光源例如：白熾燈是類似點狀的光源，而日光燈管是類似線條狀的光源，近年最熱門的光源發光二極體(LED)是一種非常良好的指向性光源，但是在照明的應用上，面光源的需求是非常大的，近10多年中，受益於顯示器技術的之快速發展與高技術成熟度，促使光學特性上具高度設計彈性、多功能性與高積體整合性等特色之微、奈米光學元件於各類光學系統中應用之重要性已吸引眾多研究與技術開發資源相繼投入。本研究嘗試運用奈米結構及多重光學散射及高效率螢光粉，實現了一個可撓式白光發光二極體元件，此發光二極體光源主要有三個特點：1. 為一均勻的面光源, 2. 可任意彎曲且適合各式穿戴式裝置, 3. 高發光效率，發光效率大於120 lm/w，4. 價格便宜，為OLED價格之1/3，5. 演色性大於95，，第二部份我們針對如何維持高發光效率的量子點發光二極體做研究。一般而言，當量子點螢光粉受熱造成分散劑揮發或受到氧化時，會產生自聚集、波長紅移與螢光共振能量轉移(FRET)現象，造成量子點螢光粉的效率及演色性隨著時間而改變。所以當量子點懸浮於分散劑中，相對而言就降低了自聚集的機率，因此我們將液狀之量子點螢光粉封裝於高透光度石英盒中，以隔絕熱與環境中濕氣與氧氣，使量子點螢光粉可維持最佳發光效率，經過一千小時信賴性測試之後，傳統量子點封裝方式發光效率下降約73%，而利用高透光度石英盒保護量子點螢光粉之封裝方式發光效率僅下降約13%，本研究成功解決傳統量子點封裝無法維持長時間有效發光之缺點，並且可將以種封裝方式應用於顯示器背光光源之中，以提升其發光效率。本研究中之光學驗證平台主要為積分球系統、背光模組量測均勻度系統。此種新穎之發光二極體元件具有很大的潛力應於照明以及生醫領域中。

關鍵字

發光二極體 ； 量子點螢光粉 ； 可撓式模組

並列摘要

This study demonstrates the flexible white LED structure with high lumen efficiency and uniform optical performance for neutral white and warm white CCT. Flip-chip LEDs were attached on a polyimide substrate with copper strips as electrical and thermal conduction paths. Yellow phosphors are mixed with polydimenthysiloxane (PDMS) to provide mechanical support and flexibility. The light efficiency of this device can reach 120 lm/W and 85% of light output uniformity of the emission area can be achieved. Moreover, the optical simulation is employed to evaluate various designs of this flexible film in order to obtain uniform output. Both the pitch between the individual devices and the thickness of the phosphor film are calculated for optimization purpose. This flexible white LED with high lumen efficiency and good reliability is suitable for the large area fixture in the general lighting applications. Another study demonstrates a novel package design to store colloidal quantum dots in liquid format and integrate it with standard LED. The high efficiency and high quality color performance for neutral white correlated color temperature can be demonstrated. The experimental results indicate that the LQD white light-emitting diode (LQD WLED) has high color quality and good reliability characteristic. The light efficiency and color rendering index (CRI) of the LQD WLED can reach to 268 lm/Wop and 95 respectively. Moreover, the glass box is employed to prevent from humidity and oxygen. With this encapsulation design, our quantum dot box can survive over 1000 hours of on-self storage time.

並列關鍵字

flexible LED ； QDs

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