Abstract
We report a two-layer, blue organic light-emitting diode with a 4,4′-bis(2,2-diphenylvinyl)-1,1′ -biphenyl emission layer and a LiF/Al cathode which has an external quantum efficiency of 1.4% and a maximum luminance of 3000 cd/m2. Insertion of the thin LiF layer results in a 50-fold increase in the device efficiency compared to a device with an aluminum only cathode, and eliminates the need for an electron-transporting layer, such as tris(8-hydroxyquinoline)aluminum. This results in a device with excellent color purity with an emission peak at 476 nm and a full width at half maximum of 78 nm. Using ultraviolet photoelectron spectroscopy, we find that the effective work-function of aluminum decreases dramatically with sub-monolayer amounts of LiF deposited on the surface.
Original language | English (US) |
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Pages (from-to) | 2324-2327 |
Number of pages | 4 |
Journal | Journal of Applied Physics |
Volume | 84 |
Issue number | 4 |
DOIs | |
State | Published - Aug 15 1998 |
ASJC Scopus subject areas
- General Physics and Astronomy