熱穩定型紫外光可交聯聚芴高分子之合成及其在高分子電激發光元件上之應用

Abstract

本研究的主要目的為合成熱穩定型紫外光可交聯聚芴高分子，實驗中利用Suzuki coupling聚合法成功合成出放光涵蓋紅綠藍三原色波長，且在芴環的九號碳位置接上含有環氧丙烷取代之苯基，其中高分子PF-B1及PPF-B1~B2為藍光材料，高分子PF-G1及PPFG1~G2為綠光材料，高分子PPFR1~R2則為紅光材料。電激發光元件的表現，根據不同的元件結構有不同的結果，以最好的亮度效率來說，藍光材料PPF-B1，驅動電壓5V，最大效率為1.27 cd/A，最大亮度為2289 cd/m2；綠光材料PPF-G2，驅動電壓6V，最大效率為5.69 cd/A，最大亮度為5605 cd/m2；紅光材料PPF-R1，驅動電壓4V，最大效率為0.16 cd/A，最大亮度為2135 cd/m2。而就藍光聚芴高分子常見的堆疊或keto defect的問題來說，所合成出來的高分子具有防止keto defect、減少迴火後分子間堆疊以及提升抗氧化性的效果。 因為環氧丙烷有可光聚的性質，形成的膜不易被溶劑溶解，所以僅利用旋轉塗佈即可製作在同一基板上同時發出三種光色的元件。另外，將PPF-B2及PPF-R1利用摻混的方式可得CIE = ( 0.335 , 0.329 )的白光元件。

The goal of this research is aimed to synthesize thermal-stable and photo-crosslinkable polyfluorenes. Three series of polyfluorenes which have oxetane-containing phenyl group at C-9 position were synthesized via the palladium-catalyzed Suzuki coupling reaction. Among them PF-B1 and PPF-B1~B2 emit blue light. PF-G1 and PPF-G1~G2 emit green light, while PPF-R1~R2 emit red light. Different electroluminescent performance was found based on the design of device structures. A double-layer device using PPF-B1 as the active layer showed a threshold voltage of 5V, a maximum brightness of 2289 cd/m2 , and a maximum current efficiency of 1.27 cd/A. Using PPF-G2 as the active layer, the device exhibited a threshold voltage of 6V, a maximum brightness of 5605 cd/m2 , and a maximum current efficiency of 5.69 cd/A. Using PPF-R1 as the active layer, the device showed a threshold voltage of 4V, a maximum brightness of 2135 cd/m2 , and a maximum current efficiency of 0.16 cd/A. Besides, the phenomena of the keto defect and aggregation are usually seen for the blue emissive polyfluorenes. The polymers synthesized in this work show good ability against the formation of keto defect, reduced aggregation of polymer chains during annealing, and enhanced stability against thermal-oxidation. Due to the photo-crosslinking property of oxetane groups, the UV-exposed thin film are not soluble in common organic solvents. A device containing blue, green, and red-emissive pixels is easy to fabricate by spin-coating and photolithography processes. In addition, a white light-emitting device was made with CIE coordinate of (0.335, 0.329), by blending PPF-R1 with host materials PPF-B2 as the active layer.