三重態-三重態湮滅上轉換電致發光元件與異質接面薄膜

Abstract

本論文分為兩個部分，第一部分將介紹一種基於三重態-三重態湮滅上轉換設計出來的有機發光二極體發光機制，利用 Tris-(8-hydroxyquinoline)aluminum (Alq3) 當作綠色的敏化層和 9,10-Bis(2-naphthyl)anthraces (ADN)作為藍色的三重態-三重態湮滅與放光層，其三重態激子可具有極高的轉換利用效率(86.1%)，元件表現比傳統的三重態-三重態湮滅有機發光二極體具有較高的元件效率與較長的操作壽命。另外，我們可以引入”三重態擴散與單重態阻擋層”提高元件的效率，並且摻雜一種磷光材料於螢光材料敏化層裡面，更可將元件效率和色彩純度表現更大幅提升。 第二部分我們使用光激發光譜系統之量測， 來瞭解以激基複合物(Exciplex)作為敏化層之化三重態-三重態湮滅上轉換的激子與載子動態特性，我們可以利用受體-橋梁-施體的這種模型來敘述我們在這使用的三層的架構，並總結出了三種方法: 增加三重態-三重態湮滅層的厚度，引入在三重態激子擴散與單重態阻擋層和於放光層內之高放光效率螢光的摻雜，都可使得藍色的三重態-三重態湮滅上轉換訊號提高。除此之外，我們也演示了三重態激子擴散與單重態阻擋層亦可利用於綠色及紅色的熱活化型延遲螢光敏化三重態-三重態湮滅上轉換，使得其轉換效率提升。

There are two parts in this dissertation. In the first part, we demonstrated a new emission mode of organic light-emitting diode (OLED) based on triplet-triplet annilihiation upconversion (TTAUC) with a high intrinsic upconversion efficiency (86.1%) by using tris-(8-hydroxyquinoline)aluminum (Alq3) and 9,10-Bis(2-naphthyl)anthraces (ADN) as green sensitizer and blue emitter, respectively. This structure improved the device efficiency and operation lifetime compared to the conventional TTA-OLEDs. Besides, a triplet-diffusion and singlet-blocking (TDSB) layer and phosphor doped fluorophore sensitizer were both employed to improve their deivce efficiency and color performances. In chapter 4, exciton and carrier dynamics of exciplex-sensitized triplet-triplet annihilation (ESTTA) were detail discussed by time-resolved photoluminescence (TrPL). This trilayer system applied in ESTTA can be described by Donor-BridgeAcceptor model with TDSB layer as its bridge. The upconversion blue emission can be enhanced by increasing the thickness of emitter layer, insertion of TDSB layer and incorporation of high quantum yield dopant inside the emitting layer. Also, green and red thermally activated delayed fluorescence (TADF)-sensitized triplet-triplet annihilation (TSTTA) were demonstrated with TDSB layer to improve their conversion efficiency.