反射不同波長之有機發光元件

Organic Light-Emitting Devices with Various Reflection Band

蕭一鵬(Yi-Peng Hsiao)

指導教授 ： 邱天隆

元智大學/電機通訊學院/光電工程學系/碩士(2012年)

摘要

我們將在本論文中展示一個具有多種顏色背景之有機發光元件(OLED)做為顯示之用，特別在戶外或強光照射下，元件可以在不消耗功率的狀態下，依然可達到顯示資訊之作用，且具有一定的對比度；在昏暗的環境下，此元件可藉由施加電壓下使用，功能如同一般的OLED顯示元件，具有無限大之對比度。此元件結構設計主要採用之光學理論為光吸收與破壞性干涉機制，利用共摻雜Ag粒子方式將一個原本不吸光之材料tris-(8-hydroxyquinoline)aluminum (Alq3)改質為具有吸收450 nm範圍光特性的材料，再將此做為共振腔夾層之介電材料，套用於一般傳統OLED元件之高反射陰極結構中。因為摻雜了導電度高的Ag奈米粒子，故此共振腔陰極也具有一定的導電特性，取代原有的陰極結構後，影響整體元件電性並不大。而元件發光特性會受到此共振腔陰極結構之影響，而使得元件的發光特性不比原有的好，但因為可大幅增加強光下的可視度且具有節能省電之優勢，故仍可以接受。

關鍵字

有機發光元件 ； 共振腔 ； 對比度 ； 電漿子吸收

並列摘要

In this thesis, we demonstrate several organic light emitting devices (OLEDs) to show the various reflection colors applied for information display, named color cathode OLED. In particular, this color cathode OLED shows a constant contrast ratio (CR) to display information without bias when it placed in outdoor or under a strong illumination. In the dark, this OLED can be lighted up as usual OLED device when provide a certain voltage, which has an infinite CR. The configuration of color cathode OLED contains two mechanisms, absorption and destructive interference. Here, the Ag nanoparticles are employed to contribute the plasmonic absorption around 450 nm by doping into tris-(8-hydroxyquinoline)aluminum (Alq3) host. This Alq3:Ag thin film possesses a good conductive property due to the high conductive Ag dopants and then inserts this film into the resonant cavity cathode of traditional OLED to be the dielectric interlayer. A little variation in electrical performance can be obtained due to this Alq3:Ag thin film with good conductivity. The optical behavior of these color cathode OLED become worse than reference OLED with a highly reflective Al cathode. This is reasonable because the backward illumination from emitting layer Alq3 is affected by rear color cathode. However, this color cathode has an advantage to perform a high CR, no matter what the ambient illumination is.

並列關鍵字

OLED ； Cavity ； Contrast Ratio ； Plasmon absorption

參考文獻

[1]Anna B. Chwang, Mark A. Rothman, ”thin film encapsulated flexible organic light electroluminescent displays", Appl.Phys.Lett., 83, 21, 2003

J. Chem.Phys., 38, 2042, 1962

[4]C.W. Tang, S.A. VanSlyke,“organic electroluminescent diodes”, Appl. Phys. Lett., 51,913, 1987

[5]H. Heil, J. Steiger, “mechanisms of injection enhancement in organic light-emitting diodes through an Al/LiF electrode”, J. Appl. Phys., 89, 420, 2001

[6]X. J. Wang, J. M. Zhao, “enhancement of electron injection in organic light-emitting devices using an Ag/LiF cathode”, J. Appl. Phys., 95, 3828, 2004