Evolution of Red Organic Light-Emitting Diodes:  Materials and Devices

Chen, Chin‐Ti

doi:10.1021/cm049679m

Cited by 750 publications

(399 citation statements)

References 63 publications

Supporting

Mentioning

389

Contrasting

Unclassified

Order By: Relevance

“…Metal-chelate complexes are often used in the OLEDs because they have a good carrier transporting capability and strong fluorescence. It is essential to design organic ligands, which play an important role in the metalchelate complex to tune the emission in a broad band [6,7]. As part of our studies on the synthesis and characterization of the ligand with two kind of aromatic heterocyclic center (DAHC) and its complexes, in the present work, we report the crystal structure of the newly designed and synthesized DAHC-type ligand, 4-(4-1H-imidazol-1-yl)phenyl-2,6-dipenylpyridine.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of 4-(4-(1H-imidazol-1-yl)phenyl)-2,6-diphenylpyridine, C26H19N3

Y.-Z.¹,

C.-X.²,

W.-T.³

et al. 2005

Zeitschrift Für Kristallographie - New Crystal Structures

View full text Add to dashboard Cite

Source of materialThe title compound was readily accessible via sequential solventless aldol condensation and Michael addition involving NaOH, followed by treatment with ammonium acetate in ethanol [1][2][3]. Acetophenone (15 mmol) and 3-(4-imidazol-1-yl-phenyl)-1-phenylpro-2-en-1-one (15 mmol) and NaOH powder (60 mmol) were crashed together with a pestle and mortar 2 h. The yellow powder was added to a stirred solution of ammonium acetate (10 g, excess) in ethanol (100 mL). The reaction mixture was heated at reflux for 10 h. After cooling to room temperature a precipitate was filtered, washed with water three times and dried to afford the product. Recrystallization from ethanol afforded white needle-shaped crystals. DiscussionLight-emitting materials are the basis for the organic light-emitting diodes (OLEDs) for flat panel display applications. A challenge in this area is to achieve light-emitting materials with longterm stability and high efficiency [4,5]. Metal-chelate complexes are often used in the OLEDs because they have a good carrier transporting capability and strong fluorescence. It is essential to design organic ligands, which play an important role in the metalchelate complex to tune the emission in a broad band [6,7]. As part of our studies on the synthesis and characterization of the ligand with two kind of aromatic heterocyclic center (DAHC) and its complexes, in the present work, we report the crystal structure of the newly designed and synthesized DAHC-type ligand, 4-(4-1H-imidazol-1-yl)phenyl-2,6-dipenylpyridine. In the title structure, the C12-N3 and C13-N3 distances of 1.350 Å and 1.346 Å, respectively, agree well with the literature data (1.340 Å), being intermediate between the values of 1.47 Å for a C-N single bond and 1.30 Å for a C=N double bond. It is the same for C-C distance and the C-N-C, C-C-N and C-C-C angles in the pyridine group [8]. These data show that the pyridine group still retains aromatic character. The C4-N2, C7-C10, C12-C21, C13-C15 distances of 1.425 Å, 1.479 Å, 1.493 Å, 1.485 Å, respectively, are close to the C-N or C-C single bond lengths, which shows that the electrons are not delocalized in the molecule. The C9-C4-N2-C2, C6-C7-C10-C11, N3-C13-C15-C20, N3-C12-C21-C26 (158.3°, 149.7°, 154.3°, 149.8°, respectively) torsion angles show clearly that the five rings do not share a common plane probably as a result of the steric configuration of C, N atoms and the free rotation around C4-N2, C7-C10, C12-C21, C13-C15 single bonds. The molecules are linked to each other by C-H···N and van der Waals forces to form the 3D network. Because of the small polarity of this organic molecule and the weak intermolecular attraction, the tendency to get faulty single crystals is large and, therefore, the N gt/Nparam ratio is smaller and the wR ref value somewhat larger than usual. These results were also observed for the structure determination of 4-(4-fluorophenyl)-2,6-diphenylpyridine [9]. Z. Kristallogr. NCS 220 (2005) [443][444]

show abstract

Section: Discussionmentioning

confidence: 99%

Crystal structure of 4-(4-(1H-imidazol-1-yl)phenyl)-2,6-diphenylpyridine, C26H19N3

Y.-Z.¹,

C.-X.²,

W.-T.³

et al. 2005

Zeitschrift Für Kristallographie - New Crystal Structures

View full text Add to dashboard Cite

show abstract

“…Fluorescent dyes are often used in conjunction with other optically active materials for tuning purposes [292,293]. Absorption/emission properties of dye molecules originate from delocalized π-electrons often on large aromatic molecules.…”

Section: Dyesmentioning

confidence: 99%

Electrospinning for nano- to mesoscale photonic structures

et al. 2016

View full text Add to dashboard Cite

Abstract:The fabrication of photonic and electronic structures and devices has directed the manufacturing industry for the last 50 years. Currently, the majority of small-scale photonic devices are created by traditional microfabrication techniques that create features by processes such as lithography and electron or ion beam direct writing. Microfabrication techniques are often expensive and slow. In contrast, the use of electrospinning (ES) in the fabrication of microand nano-scale devices for the manipulation of photons and electrons provides a relatively simple and economic viable alternative. ES involves the delivery of a polymer solution to a capillary held at a high voltage relative to the fiber deposition surface. Electrostatic force developed between the collection plate and the polymer promotes fiber deposition onto the collection plate. Issues with ES fabrication exist primarily due to an instability region that exists between the capillary and collection plate and is characterized by chaotic motion of the depositing polymer fiber. Material limitations to ES also exist; not all polymers of interest are amenable to the ES process due to process dependencies on molecular weight and chain entanglement or incompatibility with other polymers and overall process compatibility. Passive and active electronic and photonic fibers fabricated through the ES have great potential for use in light generation and collection in optical and electronic structures/ devices. ES produces fiber devices that can be combined with inorganic, metallic, biological, or organic materials for novel device design. Synergistic material selection and postprocessing techniques are also utilized for broad-ranging applications of organic nanofibers that span from biological to electronic, photovoltaic, or photonic. As the ability to electrospin optically and/or electronically active materials in a controlled manner continues to improve, the complexity and diversity of devices fabricated from this process can be expected to grow rapidly and provide an alternative to traditional resource-intensive fabrication techniques.

show abstract

“…In this paper, a series of donor-acceptor-donor red fluorescent emitters (1)(2)(3)(4) were synthesized and their electroluminescent properties were investigated. In compounds 1-4, the bulky adamantane groups were incorporated in donor moieties in order to prevent molecular aggregation between emitters, thus reducing concentration quenching.…”

Section: -8mentioning

confidence: 99%

“…In compounds 1-4, the bulky adamantane groups were incorporated in donor moieties in order to prevent molecular aggregation between emitters, thus reducing concentration quenching. Compared to the simple donor-acceptor type materials such as DCM derivatives, these donor-acceptor-donor type materials (1)(2)(3)(4) are expected to show improved color chromaticity due to the extended π-conjugation length. In addition, to study the structural effects of emitters on EL performance, various acceptor moieties containing -CN groups were introduced into red fluorescent materials 1-4.…”

Section: -8mentioning

confidence: 99%

Donor-Acceptor-Donor Type Red Fluorescent Emitters Containing Adamandane-substituted Julolidines for OLEDs

Lee¹,

Kim²,

Yoon³

2011

Bulletin of the Korean Chemical Society

View full text Add to dashboard Cite

Organic light-emitting diodes (OLEDs) have attracted much attention given their advantages to self-emission of light, wide angle, and applications in flat-panel displays. Red, green, and blue OLEDs with high efficiencies and low device driving voltages are necessary for full color displays. 1In red fluorescent OLEDs, donor-acceptor type materials such as 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino)styryl]-4H-pyran (DCM) derivatives have been widely used as red fluorescent emitters. 2-8In this paper, a series of donor-acceptor-donor red fluorescent emitters (1-4) were synthesized and their electroluminescent properties were investigated. In compounds 1-4, the bulky adamantane groups were incorporated in donor moieties in order to prevent molecular aggregation between emitters, thus reducing concentration quenching. Compared to the simple donor-acceptor type materials such as DCM derivatives, these donor-acceptor-donor type materials (1)(2)(3)(4) are expected to show improved color chromaticity due to the extended π-conjugation length. In addition, to study the structural effects of emitters on EL performance, various acceptor moieties containing -CN groups were introduced into red fluorescent materials 1-4.Usually, doping is used to obtain red emissions, in which the emitting layer is compose of a host and red dopant in order to prevent concentration quenching in the emitting layer.9-12 Recently, a co-host system was reported to overcome the incomplete energy transfer between host and dopant. [13][14][15][16] In this study, rubrene is employed as an assistant host in order to enhance energy transfer from host to dopants and thus improve the EL efficiencies.Scheme 1 shows the synthetic route of the designed donoracceptor-donor type red fluorescent emitters. 5-(3-Adamantyl-7,7-dimethyljulolidyl)carbaldehyde was prepared through Vilsmeier reaction. Compounds 1, 2, and 4 were prepared by the Knoevenagel condensation of aldehyde with the corresponding active methylene compounds (1a, 2a, and 4a). The reaction of aldehyde with phosphonate intermediates (3a) gave 3 by the Horner-Emmons reaction.The UV-vis absorption and PL spectra of red materials 1-4 are shown in Figure 1. The photophysical properties of 1-4 are summarized in Table 1. Compound 2, having phenylenediacetonitrile moiety as a acceptor, shows the longest maximum absorption and emission peak of 587 and 648 nm, respectively, while compound 1, having diaminomaleonitrile

show abstract

Evolution of Red Organic Light-Emitting Diodes: Materials and Devices

Cited by 750 publications

References 63 publications

Crystal structure of 4-(4-(1H-imidazol-1-yl)phenyl)-2,6-diphenylpyridine, C26H19N3

Crystal structure of 4-(4-(1H-imidazol-1-yl)phenyl)-2,6-diphenylpyridine, C26H19N3

Electrospinning for nano- to mesoscale photonic structures

Donor-Acceptor-Donor Type Red Fluorescent Emitters Containing Adamandane-substituted Julolidines for OLEDs

Contact Info

Product

Resources

About