Efficient electrophosphorescent polymer light-emitting devices using a Cs/Al cathode

Nakamura, A.; Tada, T.; Mizukami, M.; Yagyu, S.
January 2004
Applied Physics Letters;1/5/2004, Vol. 84 Issue 1, p130
Academic Journal
Efficient electrophosphorescent polymer light-emitting devices have been developed using a Cs/Al cathode. The materials used were a molecularly doped poly(9-vinylcarbazole)-emissive layer with electrophosphorescent complexes: bis[2-(2[sup ′]-benzothienyl)-pyridinato-N,C[sup 3[sup ′]]](acetylacetonate)Ir(III) as a red emitter, fac-tris(2-phenylpyridyl)Ir(III) as a green emitter, and bis[(4,6-difluorophenyl)-pyridinato-N,C[sup 2]](picolinato)Ir(III) as a blue emitter. The red, green, and blue electrophosphorescent emitting devices exhibited efficient emissions of 4, 31, and 14 cd/A, respectively. An inspection of secondary ion mass spectroscopy (SIMS) profiles confirmed that Cs diffuses into both Al and the emissive layer. Also, a Cs concentration of approximately 1 atomic% was estimated to be present at the interface from x-ray photoelectron spectroscopy (XPS) profiles. © 2004 American Institute of Physics.


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