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29.3: Very Bright and Efficient Top‐Emitting OLED with Ultra‐Thin Yb as Effective Electron Injector
Author(s) -
Zhu X. L.,
Sun J. X.,
Yu X. M.,
Wong M.,
Kwok H. S.
Publication year - 2006
Publication title -
sid symposium digest of technical papers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.351
H-Index - 44
eISSN - 2168-0159
pISSN - 0097-966X
DOI - 10.1889/1.2433217
Subject(s) - cathode , oled , iridium , materials science , dopant , ytterbium , diode , optoelectronics , phosphorescence , electron , layer (electronics) , electrical efficiency , injector , doping , optics , chemistry , power (physics) , nanotechnology , physics , organic chemistry , quantum mechanics , fluorescence , catalysis , thermodynamics
Very bright and efficient top‐emitting organic light‐emitting diodes (TOLEDs) using an ultra‐thin ytterbium (Yb) layer capped with a semitransparent Ag layer as the effective electron‐injection cathode were demonstrated. TOLED with Yb/Ag cathode exhibited lower operation voltage and higher power efficiency, as compared to the one with commonly used Ca/Ag cathode. With bis(2‐phenylpyridine)iridium [(ppy) 2 Ir(acac)] as the phosphorescent dopant, the Yb/Ag based TOLED showed a current efficiency of 88 cd/A and a power efficiency of 67 lm/W, considerably greater than those (56 cd/A and 44 lm/W) obtained from the corresponding bottom‐emitting one. The good performance of these TOLEDs is attributed to the efficient electrons injection from the Yb/Ag cathode as well as a micro‐cavity effect.