芘基衍生物之合成、性質探討及其在藍色有機發光二極體之應用

Abstract

本篇論文利用簡單且高產率的鈴木反應以及芳香族親核取代反應合成出四個芘基衍生物，在分子中引入具有推電子性的咔唑以及和芘同樣具有TTA-UC特性的蒽，從結構設計上來修飾芘基苯，不僅可以增加分子的電性，同時減少分子間芘基的π-π stacking，避免分子堆疊形成準分子 (Excimer)，使材料具有高螢光量子效率並且維持在深藍光的範圍。 從X-ray晶體結構分析可以看到這系列化合物的芘基、咔唑、蒽和中心苯環具有扭曲結構，可以有效減少分子的堆疊，避免螢光紅移；熱性質分析說明這幾個化合物的熱穩定性高，符合元件製作時蒸鍍的需求；光性質分析則可以看到其螢光皆在藍光的範圍，且具有高螢光量子產率；此外也引入PdOEP作為敏料，測試化合物在溶液態中TTA-UC的性質，在此條件下可以觀察到化合物dFPPP、PPA、dmPPA具有TTA-UC的現象。 在有機發光二極體的元件應用上，將化合物作為發光層的材料，應用在非摻混元件以及摻混化合物DPaNIF的元件中，其中非摻混元件以化合物dcPPP的元件表現最好，最大亮度為10120 cd/m2，最大電流效率為8.11 cd/A，最大功率為6.25 lm/W，外部量子效率可達7.24%，CIE座標為 (0.159, 0.148)，屬於深藍光的範圍。而摻混元件則以化合物PPA的元件表現最好，最大亮度為27870 cd/m2，最大電流效率為15.01 cd/A，最大功率為11.25 lm/W，外部量子效率更可高達12.94 %，從亮度5000 cd/m2開始，元件生命期為26分鐘，元件各方面效率不僅相較於市售材料DMPPP的摻混元件有所提升，其生命期更可高近兩倍，足以說明其在藍光OLED應用之潛力。

Four blue-light emitting pyrene derivatives have been synthesized by Suzuki coupling reaction and nucleophilic aromatic substitution reaction in high yield. By introducing carbazole and anthracene into pyrenylbenzene, it can not only improve the electrical properties of molecule, but also suppress the π–π stacking of pyrene. Therefore, it can prevent the intermolecular aggregation of pyrene, which tends to show a more red-shifted excimer emission and low fluorescence quantum yields. Due to the highly twisted structure of the pyrenylbenzene and phenylanthracene skeleton, these compounds exhibit a low degree of aggregation that reduces the formation of excimer. According to absorption and emission spectra and thermal analysis, these pyrene derivatives have blue light emission, high fluorescence quantum yields, and high thermal stability. The phenomenon of triplet-triplet annihilation upconversion (TTA-UC) can also be observed by inducing PdOEP as a sensitizer. In the application of non-doped blue OLEDs, the most efficient dcPPP-based device shows a high luminance of 10120 cd/m2, a maximum current efficiency of 8.11 cd/A, and a high external quantum efficiency of 7.24 % with CIE color coordinates (0.159, 0.148). In the application of doped blue OLEDs, the PPA-based device exhibited the best performance with a high luminance of 27870 cd/m2, a maximum current efficiency of 15.01 cd/A, a maximum power efficiency of 11.25 lm/W, and a high external quantum efficiency of 12.94 %. Furthermore, the lifetime of the device from 5000 cd/m2 is 26 minutes, which is about two times longer than the commercially available pyrene-based materials, DMPPP. These pyrene-based compounds have high potential in high efficiency blue OLED.