含噁唑與咔唑之共軛高分子的合成及其應用於發光二極體之研究

Abstract

本論文主要合成出一系列以噁唑(1,3,4-oxadiazole)與咔唑(carbazole)為主體的高分子，應用於有機發光二極體之發光層中的主發光體材料(Host)。利用簡易的合成方法成功合成出單體，於咔唑(carbazole)的九號位置以具有拉電子特性的噁唑(1,3,4-oxadiazole)作為取代，因分子內具有Donor-Acceptor 的結構而呈現dipolar特性，進而提高電荷轉移的效率。高分子的合成方式，應用Yamamoto聚合方法合成出單聚物(Homopolymer)，另一方面主發光體的三重態能量與分子的共軛長度有關，因此我們藉由Suzuki 偶合反應，將單體與雙硼酯化合物合成出共聚物(Copolymer)。 對這些發光材料作物性極化性上的探討：由光學性質證實高分子的主鏈共軛長度會影響三重態的能隙；P1-P4系列的Tg 為212~229℃，Td 為343~402℃，皆具有不錯的熱穩定性；電化學性質藉由循環伏安法測定P1-P4之HOMO/LUMO能階，能隙皆達3 eV以上；選擇適當的客發光體材料，以不等比例與主發光體高分子P1-P4摻混製做成元件，並且探討應用在有機發光二極體元件亮度及效率之表現。

Abstract We synthesized the conjugated polymer which combine the structure characteristics of carbazole and oxadiazole as host material. Monomer (compound 5a and 5b) has been demonstrated that one carbazole derivative containing 1,3,4-oxadiazole, has an excellent hole- and electron-transfer ability. Polymer material have electron- and hole-transporting properties are combined in one material to achieve high efficiency. The preparations of homopolymers P1 and P2 were conducted using the Yamamoto coupling reaction. Copolymer P3 and P4 were prepared by the Suzuki coupling reaction. It is shown that the triplet energy of a polymer depends on main chain length.

In the result of the physical and chemical properties these emitting materials , they have good thermal stability, Tg :212~229 ℃; Td : 343~402 ℃. The HOMO levels of the polymers are determined from the cyclic voltammetry measurements, and Eg > 3 eV. In order to study device performnace, we chose polymer P1-P4 as the host and comportable material as the guest, and a series of electroluminescent devices were fabricated.