具延遲螢光及量子點發光體之有機及混成發光元件

Abstract

本論文研究具有延遲螢光的有機放光材料、量子點與無機鹵化物鈣鈦礦之光物理與發光二極體元件製作與優化。 首先，一開始將回顧有機發光二極體的發展歷史，介紹其發光與量測原理以及熱活化延遲螢光的發展。 第3章討論兩個新穎的激態-基態複合物材料的光物理，包含時間解析光致放光與電激放光、變溫光致放光特性、激子逆向系統間轉換機制等，製作元件並藉由調整電子傳輸層結構優化效率，元件效率遠高於傳統螢光有機發光二極體最高5%的效率，最高外部量子效率可達6.1%。 第4章，我們量測量子點薄膜的光致放光量子產率，並以量子點摻雜Tris(4-carbazoyl-9-ylphenyl)amine (TCTA)後旋塗的方式製作量子點發光二極體，發現量子點與TCTA會產生垂直相分離，使量子點沉積於TCTA表面，量子點發光元件最高外部量子效率達到0.62%。 第5章中，將討論光色由綠光到深藍光的一系列熱活化延遲螢光材料，以主體客體系統將熱活化延遲螢光摻雜於高能隙材料，並以變溫時間解析頻譜與生命週期來分析其延遲螢光特性，製成有機發光二極體元件後皆高於傳統螢光的理論效率，深藍光分子的最高外部量子效率可達6.5%，CIE座標位於(0.18, 0.14)。 最後一章我們以雙源熱蒸鍍方式製作銫鉛鹵化物鈣鈦礦薄膜，量測其電荷傳輸能力與放光特性，並將其製作成有機-無機混成發光二極體。

In this thesis, We studied the device engineering and photophysical properties of delay fluorescent materials, quantum dots and inorganic halide perovskite light-emitting devices. In the introduction, We briefly reviewed the applications and current development of organic light-emitting diodes (OLEDs) for solid-state lighting and display. In the second chapter, We reviewed the history of OLEDs, and their operating principles and measurement methodology. In the third chapter, We investigated two novel excimer-formation materials, and studied the characteristics of the excimer emission. Careful transient photophysical measurements revealed the exciton up-conversion from triplet states to singlet states. The excimer-base OLEDs were fabricated and optimized by judicious selection of the electron transport materials. The device showed an external quantum efficiency (EQE) up to 6.5%, which is higher than the theoretical efficiency of the conventional fluorescent OLEDs. In the fourth chapter, We measured the photoluminescence (PL) quantum yield of the quantum dots (QDs). And fabricated quantum dot light-emitting devices by blending QDs with Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) as an emission layer. Vertical phase separation between QDs and TCTA was observed .The device with lowest QDs concentration possessed the highest EQE of 0.62%. In the fifth chapter, We studied a series of thermally activated delayed fluorescence materials, of which the emission colors range from green to deep-blue. Large bandgap materials were selected as their host materials. We measured the temperature-dependent transient PL to analyze the delay fluorescence characteristics of these compounds. The efficient deep-blue OLEDs with International Commission on Illumination (CIE) coordinates of (0.18, 0.14) and a EQE up to 6.5% were demonstrated. In chapter six, Cesium Lead halide Perovskite films were deposited by dual source thermal evaporation. We further studied the charge transport and emission characteristics of Cesium Lead halide Perovskites. Finally, We demonstrated organic-inorganic hybrid light-emitting devices.