高效率磷光有機共軛高分子發光二極體

Abstract

本論文研究由四種有機材料混合而成當作發光層的有機共軛發光二極體的特性。這四種有機材料以銥為重金屬複體為中心而使得元件達到高效率。銥這種重金屬複體能夠使得原本對形成光沒有貢獻的三重激發子，因為參雜它於有機化合物之中而形成強烈的自旋與軌道的偶合，終而能使得三重激發子能夠對形成光有貢獻。為了達到高效率的元件，我們製作了不同陰極、不同膜厚、還有單層或雙層的二極體。更進一步的，以這個高效率的綠光元件為基礎，我們指出未來製作高效率白光元件的可能辦法。綠光部分由原本四個混合物來達成。藍光部分由高分子聚合物PFO來達成。紅光的部分則由混合電動傳輸高分子聚合物TFB和發紅光的小分子DCJTB來達成。而這一層也當作電動傳輸層。獨特的緩衝層技術則被用來製作多層元件。

We study the characteristics of polymeric light-emitting diodes whose emitting layer is composed of PVK, PBD, TPD, and Ir(mppy)3. The Ir(mppy)3 is known as the heavy metal complex, and is supposed to improve the efficiency of devices because strong spin-orbit coupling in the complex enables triplet excitons, which are originally forbidden to the radiative relaxation, to relax to photons. In order to achieve the maximum luminous efficiency, we produced devices with different cathodes, thicknesses of films, and also single, and double-layer structures. Furthermore, based on these highly efficient devices, we propose a possible future direction to fabricating multilayer white PLED with high efficiency. The phosphorescent, green emitting part is achieved by the four-ingredient blend described above. Blue-emitting PFO may also be added to the blend or may be separated to another layer at the cathode side. The red emitting part is done by blending TFB and red-emitting DCJTB, and this layer also serves as the hole-transporting material. The buffer-layer technique is used to produce multilayer structures.