複合奈米結構與新穎奈米材料於氮化鎵發光二極體之研究

Abstract

近年來，發光二極體發展迅速，且逐漸受歡迎並普遍用於生活中並取代傳統的鎢絲燈，雖然白光發光二極體具有優勢，但仍有許多光特性如發光效率、色均勻度、與光品質需要優化。在本研究中第一部分，我們設計光子晶體結構如布拉格反射鏡(DBR structure)優化白光發光二極體封裝體與全彩微顯示器、奈米蜂巢結構優化白光發光二極體封裝體與可撓式發光二極體。使用布拉格反射鏡將remote 狀封裝體之正負七十度的變角度色溫控制從1758K到280K，且因為優化藍光的光萃取提升10%左右的發光效率。另一方面，在全彩微顯示器上，我們使用布拉格反射鏡提升畫素的亮度：提升194 % 藍光強度, 173 % 綠光強度及183 % 紅光強度。除了布拉格反射鏡，另一種奈米結構-奈米蜂巢結構我們使用PS奈米小球轉印於矽膠上而成蜂巢結構螢光粉薄膜，再用於remote狀封裝體與可撓式發光二極體提升分別為10%與7%左右的亮度，另一方面也優化此光電元件之色均勻度。 除了發光效率與色均勻度外，色品質如演色性Ra與R9值為另一重要課題。本論文第二部分為使用新穎的奈米與複合發光材料來製作高品質的發光二極體。在本論文中我們結合複合量子點與高分子材料PFO-Green B發光材料發光二極體，主因Green B具有較高的量子效率與較廣的頻譜，可以取代量子效率較低的藍光量子點製作效率較純量子點發光二極體高，演色性較好的複合型白光發光二極體(Ra=90)。我們也開發將PFO-Green B結合PFO族之高分子發光材料:PFO、PFO-DBT製作成光致發光薄膜應用於可撓式發光二極體，並與開發完成的量子點薄膜製作的可撓式發光二極體比較其優缺點，其中高分子材料製作之可撓式發光二極體具有較優秀的色品質(演色性Ra與R9皆為96)。另一方面，我們也開發無毒的奈米發光材料:石磨烯量子點晶體與多孔矽量子點以液態封裝的方式來製作高演色性(CRI-Ra為96、CRI-R9為88)之白光發光二極體。這些前瞻發光材料使用液態封裝方式可以提升發光二極體的發光效率與維持其高品質的演色性，而用於可撓式發光二極體可以演示優秀的演色性並於未來適合用於特殊情境照明例如美術館、廚房、與手術間用照明。

Light-emitting diodes (LEDs) have become increasingly popular and gradually replaced the traditional lighting. Although the w-LEDs to use for lighting are with many advantages, there's still room for improvement such as the luminous efficiency, uniformity, and the color rendering index (CRI). In this study, the remote phosphor LED device with DBR structure that the CCT deviation can be improved from 1758K to 280K in a range of -70 to 70 degree and the luminous flux increases more than 10% due to the enhancement of the light extraction of the blue light. When the photonic crystal DBR structure combines with the quantum dots (QDs) micro-display device, the enhanced luminous flux is 194 % (blue), 173 % (green) and 183 % (red) more than that of the samples without the DBR structure. Another investigation of the photonic crystal is that we design the honeycomb PDMS structure by the nano-sphere, and then apply to the remote phosphor w-LEDs to improve the color uniformity and luminous efficiency of 10% for remote phosphor package and 7% for flexible white LED. Besides the color uniformity and the luminous efficiency, the color rendering index (CRI) is also the important issue of w-LEDs. This research also proposed the hybrid PFO-Green B and quantum dots structure of the w-LEDs. The PFO-Green B is with the much higher quantum yield than blue quantum dot and which is with the broadband emission spectrum to improve the CRI (90). The emission polymer films fabricated by polyfluorene, PFO-Green B, and PFO-DBT have been demonstrate the excellent color quality (Both of CRI-Ra and CRI-R9 are approximate 96) flexible white LED. On the other hand, the nontoxic emission nano-scale materials have been developed by the liquid type package to demonstrate the w-LEDs with high CRI-Ra of 95 and CRI-R9 of 88. The liquid type package and for these novelty materials can improve their luminous efficiency and maintain their color quality and the flexible LEDs with the excellent color quality, which suitability for special applications, such as in the places of museum, kitchen or surgery room in the future, its high R9 and high CRI characteristics can provide high quality of services.