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
More filters
Journal ArticleDOI
Multilayer polymer light-emitting diodes : White-light emission with high efficiency
Journal ArticleDOI
Star-shaped π-conjugated oligomers and their applications in organic electronics and photonics
TL;DR: These structures are monodisperse, well-defined, discrete molecules with 100% synthetic reproducibility, and possess high purity and excellent solubility in common organic solvents and are therefore extremely attractive alternatives to conjugated polymers.
Journal ArticleDOI
Suzuki Polycondensation: Polyarylenes à la Carte
TL;DR: This review draws a rather comprehensive picture of how Suzuki polycondensation was discovered in 1989 and how it was subsequently developed into the most powerful polymerization method for polyarylenes during the last 20 years.
Journal ArticleDOI
Blue-light-emitting oligoquinolines: Synthesis, properties, and high-efficiency blue-light-emitting diodes
Christopher J. Tonzola,Abhishek P. Kulkarni,Angela P. Gifford,Werner Kaminsky,Samson A. Jenekhe +4 more
TL;DR: In this article, the synthesis, photophysics, cyclic voltammetry, and highly efficient blue electroluminescence of a series of n-type conjugated oligomers are reported.
Journal ArticleDOI
Efficient blue-emitting silafluorene–fluorene-conjugated copolymers: selective turn-off/turn-on detection of explosives
TL;DR: In this article, the synthesis and spectroscopic characterization of a series of new blue-emitting silafluorene-fluorene copolymers is described, which are synthesized using kinetically controlled hydrosilylation copolymerization of 1,1-dihydridosilafluoresne with a series 9-substituted 2,7-diethynylfluorenes.
References
More filters
Journal ArticleDOI
Fluorene-Based Copolymers Containing Dinaphtho-s-indacene as New Building Blocks for High-Efficiency and Color-Stable Blue LEDs.
TL;DR: By incorporating a new building block, 7,7,15,15-tetraoctyldinaphtho-s-indacene (NSI), into the backbone of poly(9,9-dioctylfluorene), a novel series of blue light-emitting copolymers (PFO-NSI) have been developed with high efficiency and good color stability and purity.
Journal ArticleDOI
Green top-emitting organic light emitting device with transparent Ba/Ag bilayer cathode
TL;DR: Using a vacuum thermal technique, a semitransparent Ba∕Ag bilayer cathode has been fabricated for the top-emitting organic light emitting devices in this paper, achieving optical transparency over 60% in the visible region and low sheet resistance of about 15 Ω∕sq in the Ba (10nm)∕Ga (8nm) structure.
Journal ArticleDOI
Influence of TiO 2 nanoparticles on enhancement of optoelectronic properties of PFO-based light emitting diode
TL;DR: In this paper, a PFO/TiO2 nanocomposites with different weight ratios between 5 and 35wt% were prepared using solution blending method before they were spin coated onto Indium Tin Oxide substrate.
Journal ArticleDOI
Deep blue light-emitting polymers with fluorinated backbone for enhanced color purity and efficiency
TL;DR: Two fluorene-based copolymers (PF-33F and PF-50F ) with p-difluorophenylene units in the backbone were synthesized in this paper.
Journal ArticleDOI
Decoupling 2D inter- and intrachain energy transfer in conjugated polymers.
Shashank Shekhar,Eyal Aharon,Nan Tian,Frank Galbrecht,Ullrich Scherf,Elisabeth Holder,Gitti L. Frey +6 more
TL;DR: 2D energy transfer in conjugated polymers follows mainly an interchain process, despite the absence of pi-pi interchain interactions, and differentiation between inter- and intrachain fluorene-fluorenone energy transfer is allowed.