利用濕式製程之小分子電子傳輸層提升元件效率及實現全濕式製程之有機發光二極體研究

Enhance efficiency of OLEDs by solution-processed small molecule electron transport layer & achieve all solution-processed OLEDs

陳威廷(Wei-Ting Chen)

指導教授 ： 吳志毅

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.02840

摘要

本論文主要著重於使用常見的商業性有機材料，由濕式製程的方式，製作出全濕式製程之有機發光二極體。以磷光發光、正規型元件結構與非水溶性材料(非PEDOT:PSS)等主軸來開發元件架構。
論文可分成三個部分；第一部分(第三章)是僅熱蒸鍍上電極(鋁)，其餘有機層皆以濕式製程的方式來製作元件，過程中，經由電洞傳輸層材料選擇與調整、發光層比例與參數之最佳化、導入PF-NR2製作濕式電子注入(傳輸)層，PF-NR2製程之最佳化等步驟，本研究製作出效率可達約8.18 cd/A之標準型藍光全濕式有機層之發光元件。
第二部分(第四章)仍以僅熱蒸鍍上電極(鋁)來製作元件，並由介於發光層與電洞傳輸層間之濕式介面緩衝層設計，與新增加的濕式小分子之電子傳輸層，進一步提升元件之效率，其內容包含：介面緩衝層的材料選用與材料混和測試、濕式電子傳輸層之溶劑選用與材料測試、發光層比例調整、濕式電子傳輸層製程調整與最佳化等，而製作出來的強化型藍光全濕式有機層之發光元件，其效率可達12.78 cd/A，約為標準型元件最高效率的1.56倍。
第三部分(第五章)則分成兩個部分；前半部分著重於將原本元件的藍光發光層(Firpic)，加入紅色磷光材料(Ir(piq)2 acac)與綠色磷光材料(Ir(mppy)3)的混雜，調整比例，製作出色座標CIE約(0.31, 0.37)之似白光發光層；後半部分則是將石墨烯與奈米銀線結合，製造出濕式製程之混合上電極(陰極)，經量測確定其性質後，嘗試將其應用於標準型元件之中，取代掉熱蒸鍍的鋁電極後，本研究完成了真正的透明全濕式有機發光二極體，其單面收光效率約為1.19 cd/A (雙面收光可能可達2.41 cd/A)。

關鍵字

有機發光二極體 ； 濕式製程 ； 白光 ； 石墨烯 ； 奈米銀線 ； 商業用材料

並列摘要

In this thesis, we focus on fabricating all solution-processed organic light-emitting diode (OLED) with the ordinary commercial materials. Besides, Our OLED device is designed based on conventional structure, phosphorescence emitting materials and all organic layer with water insoluble feature (non-PEDOT:PSS).

The thesis can be break into three parts. For the first part (chapter 3), our purpose is to fabricate solution-processed blue OLED with merely evaporated cathode on top of it (aluminum). We selected and optimized the proper hole transport layer, adjusted the percentage and concentration of the solution recepie in the emission layer. Also, by introducing the noval PF-NR2 materials as our electron injection layer, we successfully produced our standard blue OLED with all-solution processed organic layer. Through fine-tuning of the PF-NR2 fabrication process, the standard device achieved 8.18 cd/A as its highest current efficiency.

For the second part (chapter 4), we try to improve the device efficiency of the first part by two means. First, we inserted an solution-processed interlayer between emission layer and hole transport layer to diminish exciton quenching effect. Second, we carfully tested and selected the solvent/electron transport materials combination, in order to fabricate a complete solution-processed electron transport layer upon emission layer. With incorporated solution-processed interlayer and electron transport layer into our OLED device, we enhanced our device performance to 12.78 cd/A. Which is about 1.56 times as much as the standard device in the first part.

In the last part (chapter 5), we focused on making white emission layer and replacing evaporated cathode with solution-processed hybrid electrode. Since our previous studies (part 1 & 2) were using Firpic as the luminescent materials. We blended Ir(mppy)3 and Ir(piq)2 acac mateials into emission layer, to bring a white OLED emission layer of CIE (0.31, 0.37) under careful control of the emitting mateials ratio. On the other hand, we fabricate an innovative transparent cathode with simplified design. With the combination of graphene and silver nanowire, we surprisingly discovered a transparant, highly conductive, solution-processed cathode (hybrid electrode) that can be used in organic device. In the end, we literally produced an “all solution-process” transparent OLED, using the hybrid cathode of graphene & silver nanowire. That achieved 1.19 cd/A with one-sided emission measurement. (may be 2.41 cd/A if two-sided emission measured)

並列關鍵字

Organic light-emitting diode (OLED) ； solution-process ； white OLED ； graphene ； silver nanowire (Ag nanowire) ； commercial materials

參考文獻

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