使用新穎螢光發光體研製超高亮度下極高效率之紅光有機發光二極體

Achieving at very high luminance an extraordinarily efficient red organic light emitting diode with a novel fluorescent emitter

謝曜璟(Yao-Ching Hsieh)

指導教授 ： 周卓煇

國立清華大學/工學院/材料科學工程學系/碩士(2012年)

https://doi.org/10.6843/NTHU.2012.00359

摘要

本研究利用一新穎螢光發光體，配搭一優異的元件結構，製備出一高效率紅光有機發光二極體(Organic light-emitting diode, OLED)，其在極高亮度下，呈現突破世界紀錄之元件效率，尤其是超越同為紅光的磷光發光體。以在33,000 cd/m2亮度下為例，其外部量子效率超越5%的理論極限，而達8.5%，能量效率為3.0 lm/W，電流效率為13.6 cd/A，均為紅光OLED之世界紀錄。此紅光染料3-(N,N-diphenylamino)-7-di(cyanoyl)-5,5-spirofluorenyl -5H -dibenzo [a,d] cycloheptene (N-STIF-DCN)，搭配主體10,10'- di(biphenyl -4-yl)-9,9'-bianthracene (BANE)，在高亮度下，能有高效率的原因，可歸因於五點：一、適合紅光染料之良好主體，使發光層為客體紅光放光而非主體放光；二、低的載子注入能障，使載子較容易注入發光層結合成激子及放光；三、好的主客體能量傳遞，能將在主體上產生之激子的高能量轉移至客體上，給客體放光；四、良好的載子侷限，即使在高操作電壓下，載子也不容易從發光層流失，能形成較多的激子並放光；五、主客體能階搭配，在低操作電壓下，激子於客體上再結合及放光，而在高操作電壓下，載子可以有效地在主體上再結合形成激子，並傳遞能量給客體放光。此種主客體能階搭配之元件，能夠在主客體上生成最多激子，因此有別於傳統元件，其元件效率在高操作電壓下具有上升的現象。

關鍵字

有機發光二極體 ； 紅光 ； 高效率

並列摘要

We demonstrate at a very high luminance an extraordinary high-efficiency red fluorescent organic light emitting diode (OLED) by using a novel red emitter, 3-(N,N-diphenylamino)-7-di(cyanoyl)-5,5
-spirofluorenyl-5H-dibenzo [a,d] cycloheptene (N-STIF-DCN).The device exhibits, at 33,000 cd/m2 for example, a major peak at 612 nm with an external quantum efficiency of 8.5% with 13.6 cd/A and 3.0 lm/W, The high efficiency oberserved at the extremely high brightness may be attributed to four efficiency-effective architectural factors of the device designed as well as the unique electro-luminance effective material factor of the red dye synthesized. The five efficiency-effective architectural factors are low injection barrier, balanced carrier injection, effective carrier confinement, maximum excitons generation in both host and guest, and effective host-to-guest energy transfer.

參考文獻

2. S.R. Forrest, Nature. 2004, 428, 911-918.

9. J. H. Jou, M. F. Hsu, W. B. Wang, C. L. Chin, Y. C. Chung, C. T. Chen, J. J. Shyue, S. M. Shen, M. H. Wu, W. C. Chang, C. P. Liu, S. Z. Chen and H. Y. Chen, Chemistry of Materials. 2009, 21, 2565-2567.

10. N. Koch, A. Elschner, J. Schwartz and A. Kahn, Applied Physics Letters. 2003, 82, 2281-2283.

18. J. H. Jou, C. C. Chen, Y. C. Chung, M. T. Hsu, C. H. Wu, S. M. Shen, M. H. Wu, W. B. Wang, Y. C. Tsai, C. P. Wang and J. J. Shyue, Advanced Functional Materials 2008, 18, 121-126.

20. J. H. Jou, C. J. Wang, Y. P. Lin, Y. C. Chung, P. H. Chiang, M. H. Wu, C. P. Wang, C. L. Lai and C. Chang, Applied Physics Letters 2008, 92, 193314.