白光有機電激發光元件外部量子效率及壽命之研究

Study on external quantum efficiency and lifetime of white organic light-emitting devices

10.6342/NTU.2012.00334

林伯彥

白光有機電激發光元件 ； 壽命 ； 外部量子效率 ； 共摻雜 ； White organic light emitting ； lifetime ； external quantum efficiency ； co-doping

臺灣大學光電工程學研究所學位論文

2012年

碩士

李君浩

英文

本論文探討在不同方法量測外部量子效率的差異及有機激發元件的壽命跟高效率高色穩定度的白光有機電激發光元件之設計。 在第三章中，我們以N,N’-di(1-naphthyl)-N,N’-diphenyl-Benzidine (NPB)當作電洞傳輸層及 tris(8-hydroxyquinolinato) aluminium (Alq3)當作電子傳輸層及發光層的穩定元件，用積分球與變角度的方法去量測其外部量子效率。發現兩者間差異是一常數倍，其值約1.21。其原因為變角度量測在大角度下的量測是不準確的，不準確的原因為大角度量測時有失焦問題。 第四章中，我們使用藍光雙光發光層的架構，以共摻雜的的方式加入綠色及紅色客體材料，調變共摻雜的濃度及位置，進而實現了一個高效率極高色穩定度的白光有機電激發光元件，該元件最高功率效率可達 29.9 lm/W (5.94 nit)，外部量子效率13.23 %。元件操作亮度從100 nit到10000 nit，元件發光顏色在色座標上偏移量僅 (0.0079, 0.0092)。藉由元件的設計我們克服了多層的白光有機電激發光元件有較差色穩定度的問題。 第五章的討論為一系列單色，雙色，三色的元件壽命量測及元件衰退之探討。有機電激發光元件之壽命可以被提升，以雙發光層為元件架構或是摻雜材料特性較為穩定的綠光或紅光有機材料來減緩不穩定的藍光光材料的衰退等方式。我們實現了一個以藍光雙發光層為架構的白光有機電激發光元件，在電流密度為2.5 mA/cm2操作下，具五十個小時的壽命。

In this thesis, we study the external quantum efficiency (EQE) of different measurement methods, operational half-lifetime of OLEDs, and the design of a high efficiency and high color stability WOLEDs. In chapter 3, a stable OLED was made of N,N’-di(1-naphthyl)-N,N’-diphenyl-benzidine (NPB) as hole transport layer (HTL) and tris(8-hydroxyquinolinato) aluminium (Alq3) as the electron transport layer (ETL) and emitting layer (EML) to measure the EQE of such device via integral sphere and view angle spectra measurements. A factor existed between EQE of integral sphere and of view angle spectra, which is about 1.22. The difference is due to uncertainty of large view angle spectra measurement. The uncertainty was originated from the out of focus in large view angle. In chapter 4, a high efficiency and high color stability WOLED was demonstrated via blue double emitting layer (DEML) co-doping red and green dopant with optimized doping concentration and doping position. The WOLED exhibited peak current efficiency of 29.9 lm/w (5.84 nit), EQE of 13.23%. The CIE coordinates shift from 100 nit to 10000 nit was only (0.0079, 0.0092). A common problem existed in multi-layer WOLEDs was overcome via the design of EML. In chapter 5, a sequence of OLED including monochromatic, dichromatic, and trichromatic devices were fabricated to investigate the lifetime and discussed the degradation. The half-life time of OLEDs could be enhanced by employing DEML in device structure or doping the more stable organic material to reduce the degradation of unstable blue phosphorescent material. A WOLED using blue DEML structure with long half-lifetime of 50 hrs at driving current density of 2.5 mA/cm2 was realized.

1. 徐浩淳(2017)。有機發光二極體光萃取之研究。臺灣大學光電工程學研究所學位論文。2017。1-144。