使用新穎材料與元件結構之高效率磷光有機發光元件

Abstract

有機發光元件近年來在平面顯示器應用上漸受矚目。然而，在傳統螢光有機發光元件中僅有單重態激子能夠結合放光，因而使其發光效率受限。該理論限制在近來磷光有機發光元件的開發下已得到突破，進而使得100% 內部量子效率的實現成為可能。此一理想結果在紅光與綠光磷光元件中大致實現；至於藍光磷光元件則尚待改善。故在本論文中，主要係透過摻雜材料、主體材料與元件結構之研究，使得藍光磷光元件之效率得以有效提昇。除元件效率外，本論文的另一重心則是單層有機發光元件之研發，以求達到元件製程之簡化。 本論文中首先探討新型紅光磷光摻雜材料與多功能主體材料；其後並具體實現多層與單層之高效率紅光磷光元件。在藍光磷光元件的開發上，高三重態能階主體材料是一項重要關鍵。故本論文中首先研究具有高三重態能階之電洞傳導材料與電子傳導材料，以及高效率之藍光磷光元件結構。本論文次一主題是探討新型多功能主體材料；其後並具體實現單層之高效率紅光磷光元件。接著藉由高三重態能階雙極性傳導材料之開發，成功地將高效率單層磷光元件推展到綠光與藍光。此外，本論文中對於使用磷光主體材料以利用偶極矩作用能量轉移機制之構想亦有探討。本論文最後則研究混合螢光與磷光之白光有機發光元件，以期能實現固態照明之應用。

Organic light-emitting devices (OLEDs) have attracted growing interest for display and lighting applications in the past decade. Traditionally, the efficiency of light emission from traditional fluorescent OLEDs is limited since only the singlet states of the organic molecules contribute to the light emission. Recent demonstration of phosphorescent OLEDs renders possible achieving 100% internal quantum efficiency in OLEDs. Such an ideal had been readily demonstrated for red and green phosphorescent devices. On the other hand, there still requires much effort for blue devices. Therefore, a major part of the present dissertation is dedicated to the development of novel materials and device structures for improving blue phosphorescent OLEDs. Another focus of this dissertation is the research of single-layer devices which strongly benefit the simplification of the manufacturing processes of OLEDs. In the first part of this dissertation, novel phosporescent dopants are developed and investigated. A multifunctional host is also proposed to fabricate highly efficient single-layer red phosphorescent AOLEDs. An important issue of blue phosphorescent OLEDs is the development of high-triplet-energy host materials. Therefore, hole-transporting hosts satisfying such demanding are demonstrated by different molecular design strategies. Subsequently, the electron-transporting counterparts with high triplet energy are studied. In addition, potential electron-blocking/exciton-blocking materials are also proposed. In the second part of this dissertation, multifunctional, ambipolar, and high-triplet-energy hosts are studied for usage in fabrication of highly efficient single-layer red, green, and blue phosphorescent OLEDs. The development of large-gap phosphorescent complexes inspires the studying of novel phosphorescent host/phosphorescent dopant devices utilizing the effective Förster energy-transfer mechanism. In the final part, hybrid fluorescent/phosphorescent white OLEDs are studied considering possible applications in solid-state lighting.