Control of color and efficiency of light-emitting diodes based on polyfluorenes blended with hole-transporting molecules

Adding low-molecular-weight hole-transporting molecules (HTM) with different oxidation potentials to the polyfluorene emission layer of single-layer light-emitting diodes causes significant changes in the device properties. The pronounced increase in luminance efficiency combined with a decrease in...

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Bibliographic Details
Published in:Applied physics letters 2000-04, Vol.76 (14), p.1810-1812
Main Authors: Sainova, D., Miteva, T., Nothofer, H. G., Scherf, U., Glowacki, I., Ulanski, J., Fujikawa, H., Neher, D.
Format: Article
Language:English
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Summary:Adding low-molecular-weight hole-transporting molecules (HTM) with different oxidation potentials to the polyfluorene emission layer of single-layer light-emitting diodes causes significant changes in the device properties. The pronounced increase in luminance efficiency combined with a decrease in current is attributed to significant hole trapping, as further suggested by thermoluminescence experiments. Using a oligo-triphenylamine HTM with an ionization potential of ∼4.9 eV, light-emitting diodes with stable blue emission, a brightness of 800 cd/m2 and an efficiency of 0.87 cd/A were realized. Further, the red-emitting contribution to the spectra as observed in the pure polymer devices could be fully suppressed.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.126173