Study of the electron-injection layer of inverted top-emitting organic light emitting diodes

• Main Authors: Kao, Hsin-Min, 高薪閔
• Other Authors: Chen, Chin-Hsin
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/14580842313541978310

碩士 === 國立交通大學 === 顯示科技研究所 === 99 === Inverted type OLEDs have become increasingly important and timely for the realization of n-channel a-Si or Oxide TFT driven large panel active-matrix OLED displays. We developed inverted top-emission OLED employing highly reflective Al as cathode and a semitransparent Al/Ag as anode on glass substrate by using hole injection layer (tungsten oxide, WO3) to alleviate the severe energy level mismatch between anode and organic layer. We discovered a novel trilayer [Alq3-LiF-Mg] as the electron injection layer (EIL) in which its optimized metallic Mg component is thinner than the metallic Al in the conventional [Alq3-LiF-Al] electron-injection triad structure. This new EIL was demonstrated in an inverted top-emitting OLED (ITOLED) of green fluorescent Alq device which achieved an efficiency of up to 6.0 cd/A with a saturated CIEx,y coordinate (0.22, 0.67). The current density–voltage characteristic of this ITOLED is similar to the device with BPhen: 5% Cs2CO3 as n-type doped EIL, and its operational lifetime is also more stable.