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
Defect chemistry of polyfluorenes: identification of the origin of "interface defects" in polyfluorene based light-emitting devices.
TL;DR: Deprotonation of hydroxy terminated polyfluorenes results in a greenish emission also providing a rational explanation for so called "interface defects" in polymeric light-emitting devices (PLEDs).
Journal ArticleDOI
Preparation and optical investigation of monodisperse oligo(9,9-dioctylfluorene)s containing one fluorenone unit.
Jing Li,Ming Li,Zhishan Bo +2 more
TL;DR: A set of monodisperse oligo(9,9-dioctylfuorene)s, each containing only one fluorenone unit, was synthesized by using iterative Suzuki cross-coupling and iododesilylation reactions.
Journal ArticleDOI
Multifunctional (3-in-1) cancer theranostics applications of hydroxyquinoline-appended polyfluorene nanoparticles
Sayan Roy Chowdhury,Sudip Mukherjee,Sudip Mukherjee,Sourav Das,Sourav Das,Chitta Ranjan Patra,Chitta Ranjan Patra,Parameswar Krishnan Iyer +7 more
TL;DR: A biocompatible fluorescent hydroxyquinoline-affixed polyfluorene (PF-HQ) nanoparticle-based drug delivery system is utilized for cancer cell imaging, transport and delivery of the FDA-approved drug doxorubicin (DOX), and theranostics applications.
Journal ArticleDOI
Identification of Emissive Interface-Related Defects in Polyfluorene-Based Light Emitting Devices
TL;DR: In this paper, a defect-related emission band between 2.45 and 2.6 eV in blue light emitting polyfluorene type polymer light emitting devices is reported.
Journal ArticleDOI
On the polarization of the green emission of polyfluorenes
X. H. Yang,Dieter Neher,Christian Spitz,Egbert Zojer,Jean-Luc Brédas,R. Güntner,Ullrich Scherf +6 more
TL;DR: An experimental and theoretical study of the anisotropic optical properties of polyfluorenes (PFs) bearing ketonic defects is presented in this paper, where it is shown that the transition dipole moment of the CT π-π* transition of the defect is slightly misaligned with respect to the π −π * transition of undisturbed PF chain, and that the angle between both depends on the chain conformation.
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