Liquid Crystalline Coronene Derivatives with Extraordinary Fluorescence Properties

Rohr, U.; Schlichting, P.; Böhm, A.; Groß, Markus; Meerholz, Klaus; Bräuchle, Christoph; Müllen, Kläus

doi:10.1002/(sici)1521-3773(19980605)37:10<1434::aid-anie1434>3.3.co;2-g

Cited by 80 publications

(113 citation statements)

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“…Our aim has been the development of a new class of photofunctional liquid crystals that change the emission properties on order-order phase transitions through external stimuli. [14] Recently, intensive work has been focused on photoluminescent liquid crystals [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] as they may be used for materials such as polarizing electroluminescent materials and laser devices. However, a change of the photoluminescent color based on the dynamic change of the LC assembled structures has not been observed, except for a few examples.…”

Section: Introductionmentioning

confidence: 99%

A Stimuli‐Responsive, Photoluminescent, Anthracene‐Based Liquid Crystal: Emission Color Determined by Thermal and Mechanical Processes

Sagara

Yamane

Mutai

et al. 2009

Adv Funct Materials

249

143

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Here, a photoluminescent liquid crystal that exhibits a change of emission color on the metastable–stable phase transition induced by external stimuli is prepared. A 2,6‐diethynylanthracene derivative with amide groups and dendritic side chains exhibits a columnar phase on slow cooling from the isotropic phase and shows blue emission in this columnar phase. In contrast, a cubic phase is obtained by rapid cooling from the isotropic phase. In the cubic phase, the 2,6‐diethynylanthracene cores form excimers, resulting in yellow emission. While the columnar phase is a stable liquid‐crystalline (LC) phase, the cubic phase is a metastable LC phase. It is found that a change of the photoluminescent color from yellow to blue is observed on the cubic‐columnar phase transition induced by heating or mechanical shearing for this 2,6‐diethynylanthracene derivative in the cubic phase. This change of photoluminescent color is ascribed to the inhibition of excimer formation on the metastable–stable LC phase transition.

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Section: Introductionmentioning

confidence: 99%

A Stimuli‐Responsive, Photoluminescent, Anthracene‐Based Liquid Crystal: Emission Color Determined by Thermal and Mechanical Processes

Sagara

Yamane

Mutai

et al. 2009

Adv Funct Materials

249

143

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show abstract

“…The cross--coupling reaction is highly selective as it preferentially occurs at the iodine moieties of 15 gave the bis--carbazoyl 2 in high yield. Finally, the DBU catalysed double isomerisation--cycloaromatisation cascade 16,17 of 2 resulted in the construct of the polycyclic aromatic 3 as the major product. Compound 3 was accompanied by a small amount of the non--symmetric by--product (3'), easily removed by crystallisation.…”

Section: Resultsmentioning

confidence: 99%

Nine-ring angular fused biscarbazoloanthracene displaying a solid state based excimer emission suitable for OLED application

et al. 2016

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A new biscarbazoloanthracene consisting of nine fused aromatic rings, including two pyrrole units, has been obtained in a straightforward and convergent synthesis. Computational chemistry and conformational analysis revealed that the semiconductor's molecule is not planar, the two carbazole moieties being helical twisted from the plane of the anthracene unit. Photophysical and electrochemical measurements showed that this angular fused heteroacene has a low lying HOMO energy level with a wide band gap despite its extended π--conjugated molecular framework. Based on its relatively low--lying HOMO level, the titled compound semiconductor promises a high environmental stability in comparison to other related linear fused acenes and heteroacenes. The biscarbazoloanthracene has been applied as the light emitting layer in a white light emitting diode (WOLED). It is proposed that the white OLED feature is due to dual light emission properties from the active semiconductor layer being based on both the molecular luminescence of the small molecule and a discrete excimer emission made possible by suitable aggregates in the solid state. Noteworthy, this is the first reported example of such a behavior observed in a small molecule heteroacene rather than an oligomer or a polymer.

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“…This approach bears the disadvantage that strong intermolecular coupling often observed in p-stacks may lead to a strong reduction of the luminescence efficiency. [16] In conclusion, a number of ªphysicalº concepts have been successfully applied to outsmart waveguide losses in OLEDs, while ªchemicalº means have so far only played a minor role. Improvements of the overall light output by factors of 2±5 (some even > 10 for normal emission) have been reported.…”

Section: By Klaus Meerholz* and David C Müllermentioning

confidence: 99%

Outsmarting Waveguide Losses in Thin-Film Light-Emitting Diodes

Meerholz¹,

Müller²

2001

Adv. Funct. Mater.

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Liquid Crystalline Coronene Derivatives with Extraordinary Fluorescence Properties

Cited by 80 publications

References 1 publication

A Stimuli‐Responsive, Photoluminescent, Anthracene‐Based Liquid Crystal: Emission Color Determined by Thermal and Mechanical Processes

A Stimuli‐Responsive, Photoluminescent, Anthracene‐Based Liquid Crystal: Emission Color Determined by Thermal and Mechanical Processes

Nine-ring angular fused biscarbazoloanthracene displaying a solid state based excimer emission suitable for OLED application

Outsmarting Waveguide Losses in Thin-Film Light-Emitting Diodes

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