磷光有機電激發光元件主體材料之研究

Study of Host Materials for Phosphorescent Organic Light-emitting Devices

蔡信弘(Hsin-Hung Tsai)

指導教授 ： 李君浩

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.00973

摘要

在本篇論文中，我們使用一新合成之OXD衍生物作為發光層的發光主體，一般來說，OXD具有電子傳輸特性，將以此新材料與carbazole 為基底之主體材料，如CBP，做比較。驅動電壓方面，電流密度在100mA/cm2時，CBP基底元件為13.5V，而OXD基底的驅動電壓則為11V。而在亮度為10000cd/m2時，電流效率則由24cd/A降為到21cd/A。而在亮度為1000cd/m2時,能量效率則由8 lm/W上升到10 lm/W。
此外，我們將紅光磷光摻雜材料混入傳統電子或電洞傳輸材料中，並比較在沒有電洞阻擋層情況下元件表現，進而判斷對精簡元件結構，電洞阻擋層是否需要。實驗結果顯示，這些新結構相較於傳統元件將能有效的降低操作電壓。此外，在亮度為50 cd/m2時候，我們以電子傳輸材料作為主體且搭配電洞阻擋層的元件展現的電流效率約為16.1cd/A。這些元件還展現出較為和緩的三重態--三重態消滅。

關鍵字

磷光 ； 有機

並列摘要

In this thesis, we demonstrated phosphorescent organic light-emitting devices (PHOLEDs) by using a novel host material and two transporting materials as the host of PHOLED. We used an n-type transporting material as the host of green PHOLED. Due to the better energy alignment with adjacent transporting materials, our device exhibits a lower turn-on voltage by about 2.5 volts with the current density of 100 mA/cm2 as compared to the conventional carbazole OLED. The power efficiency is increased from 8 to 10 lm/W at the luminance of 1000 cd/m2.However, the current efficiency at 10000 cd/m2 is slightly decreased from 24 to 21 cd/A.
Besides, we used two conventional transporting materials as the host of the red PHOLED and evaluate the necessity of the hole blocking layer (HBL) by using two Ir (iridium) based red emitter. Device with electron transporting material as the host with HBL structure exhibited the highest current efficiency of 16.1 cd/A at the luminance of 50 cd/m2. Besides, devices showed limited triplet-triplet annihilation.

並列關鍵字

phosphorescent ； organic

參考文獻

[1.2] C. W Tang and S.A VanSlyke, “Organic electroluminescent diodes,” Appl. Phys. Lett. 51, 913 (1987).

[1.3] Optoelectronics Industry Development Association (OIDA), “Organic light emitting diodes (OLED) for General Illumination Update 2002”.

[1.4] C. W. Tang, S. A. VanSlyke and C. H. Chen, “Electroluminescence of doped organic thin films,” J. Appl. Phys. 65, 3610 (1989).

[1.5] J. Shi and C. W. Tang, “Doped organic electroluminescent devices with improved stability,” Appl. Phys. Lett. 70, 1665 (1997).

[1.6] M. A. Baldo, D. D. O’Brien, M. E. Thompson and S. R. Forrest, “Excitonic singlet-triplet ratio in a semiconducting organic film,” Phys. Rev. B. 60, 14422 (1999).