高分子主發光體材料的合成與研究

Abstract

本篇論文中合成了一系列含有silane片段之高分子共聚物，並探討其基本物理性質，同時以此一系列高分子共聚物作為主發光體，應用於綠色磷光電激發光高分子二極體。在此系列高分子中，因silane片段的導入，適度的阻斷其共軛長度使本系列高分子具有相當大的能隙，使其適用為主發光體材料。此外，此系列高分子化合物因具有相當高的玻璃轉移溫度，因此其固態薄膜經過加熱處理後，其吸收與放射圖譜無顯著變化。而此系列化合物，因在主鏈fluorene上加上傳電洞的carbazole片段，促成高分子具有較佳之電洞傳輸能力，以提高元件之效率。將高分子P2、P3與P4作為主發光體材料，綠色磷光材料Ir(PPy)3作為摻混材料製成高分子元件後，以P4為主發光體材料所製成之元件(Device 3)具有最佳的效率表現，其最大外部量子效率高達9.2 %，最大發光效率高達 32 cd/A。

We report a series of high energy gap organosilicon compounds and they were employed as host materials in the emissive layer of electrophosphorescent organic light-emitting diodes(OLEDs)The results from photophysical studies and electrical chemistry showed that these copolymers possess a wide band gap(3.44-3.67 eV)because of entering tetraphenylsilane derivatives disrupt the conjugation length of polymer. Also these copolymers exhibited high glass transition temperature (Tg >200 ℃). In order to improve hole transporting ability, we introduced the carbazole as side group on the polymer. Furthermore, from the UV-violet and PL spectra in thin films, after thermal experiment, these spectra of copolymers are almost unchanged because of high glass transition temperature. It is interesting that only device 3 using P4 as host in polymer light-emitting diodes containing Ir(ppy)3 as dopant emit high-efficiency green light. This phenomenon implied the balanced carriers injection in P4-based device. The P4-based device shows maximal external quantum and luminance efficiencies were, respectively, 9.2 % photons/electrons and 32 cd/A at 6109 cd/m2 and with Commission Internationale de l’Eclairage coordinates of (0.24, 0.65).