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White‐Light‐Emitting Diodes Based on Iridium Complexes via Efficient Energy Transfer from a Conjugated Polymer
Author(s) -
Kim T.H.,
Lee H. K.,
Park O O.,
Chin B. D.,
Lee S.H.,
Kim J. K.
Publication year - 2006
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200500621
Subject(s) - materials science , polyfluorene , iridium , conjugated system , electroluminescence , polymer , carbazole , phosphorescence , photochemistry , optoelectronics , diode , miscibility , doping , chemical engineering , nanotechnology , fluorescence , optics , organic chemistry , chemistry , composite material , layer (electronics) , physics , catalysis , engineering
Abstract Efficient white‐light‐emitting diodes (WLEDs) have been developed using a polyfluorene‐type blue‐emitting conjugated polymer doped with green and red phosphorescent dyes. The emission spectrum of the conjugated polymer, which has a very high luminescent efficiency, shows a large spectral overlap with the absorbance of green and red iridium complexes. Also, efficient energy transfer from the conjugated polymer to the iridium complexes is observed. Poly( N ‐vinyl carbazole) is used to improve the miscibility between conjugated polymer and iridium complexes because of their poor chemical compatibility and phase separation. A white emission spectrum is easily obtained by varying the contents of the three materials and controlling the phase morphology. Moreover, these WLEDs show a voltage‐independent electroluminescence owing to the threshold and driving voltage of the three materials being similar as a result of energy transfer.