Compositions – Liquid crystal compositions – Containing charge-transfer agents
Patent
1998-11-20
2000-08-08
Kelly, C. H.
Compositions
Liquid crystal compositions
Containing charge-transfer agents
25229962, 430 56, C09K 1958, C09K 1932, G03G 1500
Patent
active
060997508
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the use of compounds which are in the plastic columnar discotic liquid-crystal phase for transport of electric charges.
In addition, the invention relates to electronic components containing these compounds and mixtures of these compounds with columnar discotic helical and/or columnar discotic liquid-crystal compounds.
BACKGROUND OF THE INVENTION
Photoconductive organic polymers are an interesting class of materials and are used on a large scale industrially in copiers, laser printers and offset printing plates. Discotic liquid-crystal compounds such as hexapentyloxytriphenylenes having charge carrier mobilities of approx. 10.sup.-3 cm.sup.2 /Vs are of special interest as organic photoconductors (Adam et al., Physical Review Letters 70 (1993) 457-460).
Some discotic columnar liquid-crystal compounds are known to be able to form higher-order phases in addition to or instead of a columnar phase. For example, older German patent application P4429597.9 describes discotic columnar liquid-crystal compounds which form a higher-order helical phase in certain temperature ranges. Such liquid-crystal phases have a high charge carrier mobility. However, many of these known organic photoconductors leave much to be desired regarding their chemical stability.
SUMMARY OF THE INVENTION
The object of the present invention was therefore to provide organic compounds that have liquid-crystal properties and have a high photoconductivity and charge carrier mobility with good chemical stability in the liquid-crystal state, and are suitable for use as charge transport compounds in photocopiers or in electronic components.
It has accordingly been found that liquid-crystal compounds which are in the plastic columnar discotic phase have an especially high charge carrier mobility and good chemical stability and that therefore compounds which are in this liquid-crystal phase are especially suitable for transport of electric charges.
DETAILED DESCRIPTION OF THE INVENTION
Plastic columnar discotic phase is understood here to refer to a liquid-crystal phase which is a state of order between the crystalline state and the discotic columnar liquid-crystal state. This state of order can be observed in heating from the crystalline state or in cooling from the isotropic liquid state or less ordered liquid-crystal state. Although the axes of the columns are oriented in the discotic columnar liquid-crystal state, the individual columns can move along their axes. This movement is so restricted in the plastic columnar discotic state that X-ray diffraction experiments yield mixed reflections (hkl) like those characteristic of the crystalline state. In contrast with the crystalline state, the plastic columnar discotic phases, however are mostly viscous and not solid, because the molecules can rotate about the axis of the column. Such liquid-crystal compounds can therefore be processed homogeneously over a large area and are also suitable for applications for which the dimension of crystalline semiconductors is a limiting factor. Especially with oligomeric compounds, the plastic columnar discotic phase can also be observed in the vitreous solidified state.
These plastic columnar discotic liquid-crystal phases usually have charge carrier mobilities of more than 10.sup.-2 cm.sup.2 /Vs. Any discotic liquid-crystal compounds having plastic columnar discotic phases in certain temperature ranges may be used according to this invention. Thus the compounds according to this invention may be derived from the following parent substances, for example: triphenylene, dibenzopyrene, benzene, naphthalene, anthracene, phenanthrene, benzophenanthrene, pentahelicene, perylene, decacyclene, truxene, rufigallol, pyrene, fluorene, indene, coronene or corresponding aromatic systems in which one or more ring carbons are replaced by nitrogen, oxygen or sulfur, or they may be derived from tricycloquinazoline, phthalocyanine or porphyrin.
With all these discotic liquid-crystal compounds, the substitution pattern
REFERENCES:
patent: 4430650 (1984-02-01), Billard et al.
patent: 4631143 (1986-12-01), Praefcke et al.
patent: 4657694 (1987-04-01), Heeger et al.
patent: 4769448 (1988-09-01), Heegere et al.
patent: 5384068 (1995-01-01), Bock et al.
patent: 5635105 (1997-06-01), Kawata et al.
patent: 5718838 (1998-02-01), Okazaki
patent: 5730903 (1998-03-01), Okazaki
patent: 5736068 (1998-04-01), Haeussling et al.
patent: 5750050 (1998-05-01), Goodby et al.
Etzbach Karl-Heinz
Glusen Birgit
Haarer Dietrich
Kettner Andreas
Paulus Wolfgang
Kelly C. H.
Siemens Aktiengesellschaft
LandOfFree
Use of organic compounds in the plastic columnar discotic liquid does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Use of organic compounds in the plastic columnar discotic liquid, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of organic compounds in the plastic columnar discotic liquid will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1147160