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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Journal ArticleDOI
Synthesis and Characterization of Pyrene‐Centered Starburst Oligofluorenes
Feng Liu,Wen-Yong Lai,Chao Tang,Hongbin Wu,Qing-Quan Chen,Bo Peng,Wei Wei,Wei Huang,Yong Cao +8 more
TL;DR: A series of starburst materials (T1-T3) based on a pyrene core with four oligofluorene arms of different length have been synthesized and characterized as mentioned in this paper.
Journal ArticleDOI
N-2-aryl-1,2,3-triazoles: a novel class of UV/blue-light-emitting fluorophores with tunable optical properties.
TL;DR: The computational studies along with X-ray crystal structures indicated the significance of the effective conjugation between triazole ring and aryl groups on the N-2 position, and the planar intramolecular charge transfer (PICT) mechanism was proposed, which was supported by solvent effect studies.
Journal ArticleDOI
High-efficiency red and green light-emitting polymers based on a novel wide bandgap poly(2,7-silafluorene)
TL;DR: In this paper, a new type of high-efficiency red and green light-emitting polymer was synthesized via the Suzuki coupling reaction by incorporating narrow bandgap (NBG) comonomers 4,7-di(4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (DHTBT) and 2,1-3-benedictine (BT), respectively, into the backbone of poly(2.7-silafluorene) (PSiF) copolymers.
Journal ArticleDOI
White light from polymer light-emitting diodes: Utilization of fluorenone defects and exciplex
TL;DR: In this paper, a white light polymer light-emitting diode was demonstrated with a double layer configuration: poly[N,N′-bis(4-butylphenyl)-N, N,N-bis (phenyl)benzidine] (poly-TPD) blended with poly(N-vinylcarbazole) as both hole-transporting layer and electron blocking layer, blue-emissive poly(9,9-dihexylfluorene-alt-co-2,5-dioctyloxy
Journal ArticleDOI
Enhancement of spectral stability and efficiency on blue light-emitters via introducing dibenzothiophene-S,S-dioxide isomers into polyfluorene backbone
TL;DR: In this paper, Dai et al. showed that the FSO unit acts as a deep trap for electron in the polyfluorene backbone, which could suppress the long wavelength emission.
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