Efficient blue electroluminescence from a fluorinated polyquinoline

A widely applicable electroabsorption technique to measure internal electric fields in organic light‐emitting diodes is presented. The technique exploits the change in the a.c. electroabsorption response in the presence of a d.c. electric field. The electroabsorption signal is modulated at the fundamental frequency of the a.c. test signal, in addition to the usual modulation at the second harmonic frequency, when a d.c. bias is present. In metal/organic film/metal devices employing different metal contacts there is a built‐in electric field in the organic film caused by the difference in work function between the two contacts. The electroabsorption response at the fundamental frequency of the applied a.c. bias is measured as a function of an external d.c. bias. The electroabsorption signal is nulled when the applied d.c. bias cancels the built‐in electric field established by the different metals. We apply this technique to measure changes in metal–polymer Schottky barrier heights as a function of the contact metal. In metal/multiple organic films/metal structures the electroabsorption signals from the constituent organic films are identified spectroscopically and measured at both the fundamental and second harmonic frequency of the a.c. test signal. The amplitudes of the electroabsorption responses are then used to determine the a.c. and d.c. electric fields present in the organic layers. We apply this technique to determine the d.c. electric field distribution within a multi‐layer organic light‐emitting diode. These results highlight the general applicability of electroabsorption methods to probe internal electric fields in organic light‐emitting diodes. © 1997 John Wiley & Sons, Ltd.

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“…6(a) and (b), respectively. The electrical and optical characteristics of these LEDs have been previously described [23].…”

Section: Multilayer Organic Ledmentioning

confidence: 99%

Measuring internal electric fields in organic light-emitting diodes using electroabsorption spectroscopy

Campbell

Ferraris

Hagler

et al. 1997

Polym. Adv. Technol.

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“…Therefore, balanced charge injections from both electrodes are important for high device efficiencies [13,14]. It was reported that the HOMO-LUMO energy levels could be lowered for balanced charge injections by the introduction of electron-withdrawing substituents onto the conjugated main chain of the polymer.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Luminescent Properties of Tetrafluorophenyl Containing Poly(p-phenylenevinylene) Derivatives

Ahn

2015

Transactions on Electrical and Electronic Materials

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To investigate the effect of fluoro groups substitution on poly(p-phenylenevinylene) derivatives, poly(2,3,5,6-tetrafluoro-p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCTF-PPV, and poly [2,3,5,6-tetrafluorop-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], PMTF-PPV, were synthesized by the well-known Wittig condensation polymerization process. To compare the influences of fluoro groups, no fluoro groups containing model polymers, poly(p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCP-PPV and poly[p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], p-PMEH-PPV, were also synthesized. The resulting polymers were completely soluble in common organic solvents and exhibited good thermal stability up to 300℃. The polymers showed UV-visible absorbance and photoluminescence (PL) in the ranges of 259~452 nm and 500~580 nm, respectively. The tetrafluorophenyl containing PCTF-PPV and PMTF-PPV showed relatively red-shifted PL peaks at 521 nm and 580 nm, respectively, compared to that of non-fluoro groups containing polymers (PCP-PPV: 500 nm and p-PMEH-PPV: 539 nm). The single-layer light-emitting diode was fabricated in a configuration of ITO/polymer/Al. Electroluminescene (EL) emissions of PCP-PPV, PCTF-PPV, p-PMEH-PPV and PMTF-PPV were shown at 507, 524, 556, and 616 nm, respectively.

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“…Over the last decade, conjugated polymers have attracted great interest due to most of the polymers can be processed from solution at room temperature and their potential application in developing large scopes, flexible, lightweight and low cost organic light emitting diodes (OLEDs) and organic solar cells (OSCs) [1,2]. Unfortunately, the electrical and optical properties of these polymers do not compare to those of inorganic semiconductor materials, thus, polymer-based devices have performed poorly in common.…”

Section: Introductionmentioning

confidence: 99%

Electrical and Optical Properties of the Hybrid TiO\(_{2}\) Nanocrystals - MEH-PPV Thin Films

Ha¹

2009

Comm. in Phys.

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Abstract. Recently, the conjugated polymer -inorganic nanocomposites have been increasingly studied because of their enhanced optical and electronic properties as well as their potential application in developing optoelectronic devices. In this study nanocomposite materials thin films based on poly [2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and nanocrystalline TiO2 (nc-TiO2) have been fabricated. The photoluminescence (PL) spectra of pure MEH-PPV and nanohybrid films have shown that the excitation at a 377 nm wavelength leads to the strongly enhanced performance in photoluminescent intensity due to the compositions of TiO2 component. Current-voltage (I-V) characteristics of multi-layer device Al//MEH-PPV:nc-TiO2//PEDOT: PSS//ITO//glass were investigated. The results show that the hybrid MEH-PPV:nc-TiO2 materials with high concentrations of TiO2 (> 25%) can be expected to be a good candidate for photovoltaic solar cell applications whereas those with lower concentrations of TiO2 are more suitable for organic light-emitting diodes (OLEDs).

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Efficient blue electroluminescence from a fluorinated polyquinoline

Cited by 202 publications

References 19 publications

Measuring internal electric fields in organic light-emitting diodes using electroabsorption spectroscopy

Measuring internal electric fields in organic light-emitting diodes using electroabsorption spectroscopy

Synthesis and Luminescent Properties of Tetrafluorophenyl Containing Poly(p-phenylenevinylene) Derivatives

Electrical and Optical Properties of the Hybrid TiO\(_{2}\) Nanocrystals - MEH-PPV Thin Films

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