均勻混摻型電洞傳輸層之高穩定性有機電激發光元件

Abstract

在本論文中，成功地運用2-methyl-9,10-di(2-naphthyl)anthracene (MADN) 和N,N’-bis(1-naphthyl)-N,N’-diphenyl,1,1’-biphenyl-4,4’- diamine (NPB)依3：7比例所組成之均勻混摻型電洞傳輸層(UM-HTL)來達成高穩定性有機發光二極體元件。在10-(2-benzothiazolyl) -1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]-pyrano[6,7,8-ij]quinolizin-11-one (C-545T)摻雜的綠光元件中，採用UM-HTL和傳統結構之元件相比，元件半衰期(亮度換算成100 nits)可被大幅提升將近3倍(52200小時)，而且重要的是元件的驅動電壓、發光效率和發光顏色依舊保有原本優越表現。這樣優越之穩定度改良結果最主要可以歸因於UM-HTL成功抑制正電荷在發光層的累積，使得元件穩定度可以明顯獲得改善。此外，再將UM-HTL運用在以MADN為主的藍光系統中，元件穩定度亦可以顯著提升至少有1.5倍之多，且藍光元件本身的優越特性和發光顏色均不受影響。這便可以證明UM-HTL是可以被運用於增進各個光色元件的穩定度，而且不會影響到其元件自身的發光特性。其次，UM-HTL更擁有優異的薄膜熱性質，可以解決ㄧ般電洞傳輸材料低Tg問題。這些優勢都使得UM-HTL具備有取代各個光色元件中的傳統電洞傳輸層的潛力。

In this thesis, highly stable organic light emitting devices was made by using a uniformly mixed hole transport layer (UM-HTL) composed of a mixture of 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) and N,N’-bis(1-naphthyl)-N,N’-diphenyl,1,1’-biphenyl-4,4’-diamine (NPB) in a 3:7 (MADN:NPB) ratio. In 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl- 2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]-pyrano[6,7,8-ij]quinolizin-11-one (C-545T) doped green device, the stability of device with a UM-HTL can be greatly improved to 3 times (initial luminance normalized to 100 nits, 52200 hrs) longer than that of the conventional NPB based HTL without deteriorating on its driving voltage, current efficiency and emissive color significantly. This improvement in stability can be attributed to the fact that the accumulations of positive charge in emission layer have been effectively suppressed. Moreover, using UM-HTL in MADN based blue device systems, the stability of device also can be greatly improved to at least 1.5 times longer than that of the conventional NPB based HTL without deteriorating on its driving voltage, current efficiency and emissive color significantly. These results indicated that UM-HTL can improve the stability of device with any kind of emission color without affecting its emission property. Furthermore, UM-HTL has good thin film thermal property to solve the issue of low Tg in conventional HTL materials. Hence, this made UM-HTL a potential candidate to replace the conventional HTL for each emission color.