以芴為主體之有機光電材料的設計、合成與性質

Abstract

有機光電元件相較於傳統的無機光電元件，具有低成本、製程難度較低、可撓性等優勢，目前已吸引世界各地的學者和公司趨之若鶩。在眾多芳香類化合物中，芴(fluorene)擁有極大的潛力。它的結構剛硬，使其具有相當高的光激螢光量子產率。此外，透過適當的分子修飾，能輕易的調整芴衍生物的物理和化學性質。因此，以芴為主體的有機材料目前被廣泛應用於有機光電領域。 在本篇論文中，我們設計並合成了一系列以芴為主體的有機光電材料，應用於有機發光二極體(organic light-emitting diode, OLED)和有機雷射。相關的材料性質將一並在本文中分析與討論。在第一章中，將簡單的介紹有機光電元件和芴的特性。第二章和第三章是關於激態複合物(exciplex)應用在有機發光二極體上的研究，透過激態複合物系統以增加藍光元件的效率。在第二章中，我們藉由在電洞傳輸材料(hole-transporting material, HTM)上引入拉電子基，以調整其能階。希望所得的激態複合物具有較大的能隙和放出深藍的光色，以做為藍光發光體的主體。另一方面，第三章是關於新型電子傳輸材料(electron-transporting material, ETM)應用於深藍光激態複合物的研究。我們在芴主幹的不同位置上，進行氰基取代，藉此調整其最低未佔有分子軌域(lowest unoccupied molecular orbital, LUMO)之能階。相關的性質與元件分析將於文中進行探討。第四章闡述分子內三重態-三重態消滅(triplet-triplet annihilation, TTA)性質的發光體的概念。我們以芴做為架橋，連接兩個二苯基蒽(diphenylanthracene)，以實現分子內三重態-三重態淬熄。在第五章中，我們設計並合成了新型的有機雷射材料。透過在低聚芴(oligofluorene)的骨架上引入氰基，以增加分子間的偶極-偶極(dipole-dipole interaction)，期望能改善有機雷射元件的效率。

Organic optoelectronic devices have attracted intense attention from researchers and companies all over the world for their low cost, ease of production, and mechanical flexibility compared to traditional inorganic optoelectronic devices. Among various aromatic molecules, fluorene is rigid with high photoluminescence quantum yield (PLQY). With proper modification, physical and chemical properties of fluorene derivatives can be easily tuned. As a consequence, fluorene-based molecules are widely used in organic optoelectronic devices. In this thesis, a series of fluorene-based organic optoelectronic materials utilized in organic light-emitting diodes (OLEDs) and organic laser were designed, synthesized, and characterized. In the 1st chapter, organic optoelectronic devices and characteristics of fluorene were briefly introduced. The 2nd and 3rd chapters elaborate the concept of improving the efficiency of blue emission device by applying exciplex system in OLED devices. In the 2nd chapter, the idea for energy level adjustment on hole-transporting materials (HTMs) by introducing electron-withdrawing cyano group was demonstrated. It is expected that the resulting exciplexes with wider optical energy gaps may serve as deep blue hosts for blue emitters. On the other hand, the 3rd chapter focuses on novel electron-transporting materials (ETMs) for exciplex-based OLED. In order to adjust the energy levels of the lowest unoccupied molecular orbital (LUMO), electron-withdrawing cyano group was introduced onto different positions of the fluorene core. Thus, a series of ETMs for deep blue exciplex were synthesized and examined. The 4th chapter manifests the concept of intramolecular triplet-triplet annihilation (TTA) emitter, and it shows great promise for blue emission devices. In this regard, fluorene serves as bridge to link two diphenylanthracenes to realize intramolecular TTA. Last, novel design of organic laser gain materials is demonstrated in the 5th chapter. Cyano group was introduced onto the backbone of oligofluorenes to enhance dipole-dipole interaction between molecules, and thus improving the performances of organic laser devices.