Open Access
Stabilized Blue Emission from Polyfluorene-Based Light-Emitting Diodes: Elimination of Fluorenone Defects
Xiong Gong
- Vol. 13
TLDR
In this paper, the photoluminescence (PL) and electroluminescent (EL) of polyfluorene (PF)-based light-emitting diodes (LEDs) were studied and it was shown that the low-energy emission band originates from fluorenone defects which are introduced by photo-oxidization, thermal oxidation, or during device fabrication.Abstract:
Polyfluorene (PF)-based light-emitting diodes (LEDs) typically exhibit device degradation under operation with the emergence of a strong low-energy emission band (at ∼ 2.2–2.4 eV). This longer wavelength band converts the desired blue emission to blue–green or even yellow. We have studied both the photoluminescence (PL) and electroluminescence (EL) of PFs with different molecular structures and found that the low-energy emission band originates from fluorenone defects which are introduced by photo-oxidization, thermal oxidation, or during device fabrication. X-ray photo-emission spectroscopy (XPS) results show that the oxidation of PF is strongly catalyzed by the presence of calcium. The fluorenone defects generate a stronger contribution to the EL than to the PL. By utilization of a novel electron-transporting material as a buffer layer between the emissive PF and the Ca/Ag (Ba/Ag) cathode, the blue EL emission from the PF was stabilized.read more
Citations
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Optimizing OLED Efficacy of 2,7‐Diconjugated 9,9‐Dialkylfluorenes by Variation of Periphery Substitution and Conjugation Length
TL;DR: The photoluminescence (PL) and electroluminescent (EL) of four 2,7-bis(phenylethenyl)fluorenes (OFPVs) and two 2.7-diphenylfluorenes(OFPVs) are compared to evaluate effects of nonconjugating peripheral substitution and conjugation length on their EL emissions as discussed by the authors, and the OFPVs exhibit very similar PL spectra with 460-480 nm emission maxima but show large variation in the organic light-emitting di
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Starburst 4,4′,4′′-tris(carbazol-9-yl)-triphenylamine-based deep-blue fluorescent emitters with tunable oligophenyl length for solution-processed undoped organic light-emitting diodes
TL;DR: In this paper, a series of star-shaped deep-blue fluorescent emitters (2P-TCTA, 3P-, 4P-, 5P-, 6P-and 7P TCTA) have been successfully developed via a simple extension of the oligophenyl chain between two N atoms.
Journal ArticleDOI
Blue organic light emitting devices with improved colour purity and efficiency through blending of poly(9,9-dioctyl-2,7-fluorene) with an electron transporting material
TL;DR: In this paper, a single blended layer of poly(9,9-dioctyl-2,7-fluorene) (PFO) or poly[9, 9-bis(4-octyloxyphenyl)-2, 7-fluororene] and an electron transporting material (DFD) has been fabricated.
Journal ArticleDOI
The Effect of Ketone Defects on the Charge Transport and Charge Recombination in Polyfluorenes
Martijn Kuik,Gert-Jan A. H. Wetzelaer,Jurre G. Ladde,Herman T. Nicolai,Jurjen Wildeman,Jörgen Sweelssen,Paul W. M. Blom +6 more
TL;DR: In this article, the effect of on-chain ketone defects on the charge transport of the polyfluorene derivative poly(9,9-dioctylfluorene) (PFO) is investigated.
Journal ArticleDOI
Synthesis of conjugated 2,7-bis(trimethylsilylethynyl)-(phenylethynyl)nfluoren-9-one and 9-(p-methoxyphenyl)-9-methyl derivatives: optical properties
TL;DR: In this paper, the synthesis of conjugated 2,7-bis(trimethylsilylethynyl)-(phenyleth-ynyl)nfluoren-9-one (or the 9-(p-methoxyphenyl)-9-methyl) structures was carried out by the heterocoupling reaction between the 2.7-di(halo)fluoren, 9-one and p-trimethylfluorene, catalyzed by the dichloro bis(triphenylphosphine)pall
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