Efficient green light‐emitting diodes from a phenylated derivative of poly(p‐phenylene–vinylene)
作者:
F. Cacialli,
R. H. Friend,
N. Haylett,
R. Daik,
W. J. Feast,
D. A. dos Santos,
J. L. Bre´das,
期刊:
Applied Physics Letters
(AIP Available online 1996)
卷期:
Volume 69,
issue 25
页码: 3794-3796
ISSN:0003-6951
年代: 1996
DOI:10.1063/1.117001
出版商: AIP
数据来源: AIP
摘要:
We have used polyvinylcarbazole, PVK, in combination with poly(p‐phenylene vinylene), PPV and a green‐emitting, soluble derivative, poly(4,4′‐diphenylene diphenylvinylene) or briefly PDPV, to fabricate triple‐layer light‐emitting diodes PPV/PVK/PDPV/metal, with indium tin oxide as the anode. We report luminances in excess of 1300 cd/m2with Al cathodes, turn‐on voltages of ∼8 V in structures 300 nm thick, and internal efficiencies in the range 0.4%–0.8% for Al and Ca cathodes; at least ten times higher than for single‐layer PDPV devices. Quantum efficiencies for Ca or Al electrodes are only a factor 1.5 different. The improvements over single‐layer PDPV devices are considered to be due to better hole injection by PPV and to the formation of a hole barrier at the PPV/PVK interface, which forces a better balance of the electron and hole currents. ©1996 American Institute of Physics.
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