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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High-efficiency multilayer polymeric blue light-emitting diodes using boronate esters as cross-linking linkages
TL;DR: In this article, two alternating triphenylamine-fluorene copolymers with hydroxyl groups on the side chains and tris(4-dihydroxyboranylphenyl)amine (TBPA) as a crosslinker have been designed and synthesized.
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Time-resolved measurements of photoinduced electron transfer from polyfluorene to C 60
TL;DR: In this paper, the photo-induced charge transfer reaction occurs with a characteristic time constant of approximately 3 ps and the decay of the neutral excited state and the growth of the ionic excited state have been time resolved using the stimulated emission and photoinduced absorption spectra.
Journal ArticleDOI
Synthesis and characterization of spirobifluorene-based polymers for organic light-emitting diode applications
Md. Anwarul Karim,Young-Rae Cho,Jin Su Park,Kyung Jin Yoon,Seungjoon Lee,Sung-Ho Jin,Gi-Dong Lee,Yeong-Soon Gal +7 more
TL;DR: The following series of blue EL polymers was synthesized using the Suzuki polymerization method and were completely soluble in common organic solvents and were easily spin-coated onto an indium tin oxide (ITO) substrate.
Journal ArticleDOI
A novel ambipolar polymer: from organic thin-film transistors to enhanced air-stable blue light emitting diodes
TL;DR: In this article, a donor-acceptor (DA) polymer based on naphthalene diimide (NDI) as strong acceptor and n-phenyl-dithieno[3,2-b:2′,3′-d]pyrrole (DTP) as a strong donor was presented.
Journal ArticleDOI
Blue light-emitting polymers containing ortho-linking carbazole-based benzothiophene-S, S-dioxide derivative
TL;DR: In this article, the blue light emitting polymers PF-CzBTOs and PCz-CZbTOs were synthesized by Suzuki polycondensation via ortho-linking N -(2-decyltetradecyl) carbazole bis- [2,3-b,6,7-b]benzo[ d ]thiophene-S,S -dioxide (CzbTO) into the polyfluorene (PF) and polycarbazole (PCz) backbone, respectively.
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