Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2002-07-09
2004-10-05
Lambkin, Deborah C. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C252S500000, C528S377000, C106S031920, C385S141000, C359S321000
Reexamination Certificate
active
06800763
ABSTRACT:
FIELD OF INVENTION
The invention relates to reactive thienothiophenes. The invention further relates to their use as semiconductors or charge transport materials, in optical, electrooptical or electronic devices like for example organic field effect transistors (FET or OFET) for thin film transistor liquid crystal displays and integrated circuit devices such as radio frequency identification (RFID) tags, electroluminescent devices in flat panel displays, and in photovoltaic and sensor devices. The invention further relates to a field effect transistor, light emitting device or identification (ID) tag comprising the reactive thienothiophenes.
BACKGROUND AND PRIOR ART
Organic materials have recently shown promise as the active layer in organic based thin film transistors and organic field effect transistors [see H. E. Katz, Z. Bao and S. L. Gilat,
Acc. Chem. Res
., 2001, 34, 5, 359]. Such devices have potential applications in smart cards, security tags and the switching element in flat panel displays. Organic materials are envisaged to have substantial cost advantages over their silicon analogues if they can be deposited from solution, as this enables a fast, large-area fabrication route.
The performance of the device is principally based upon the charge carrier mobility of the semiconducting material and the current on/off ratio, so the ideal semiconductor should have a low conductivity in the off state, combined with a high charge carrier mobility (>1×10
−3
cm
2
V
−1
s
−1
). In addition, it is important that the semiconducting material is relatively stable to oxidation i.e. it has a high ionization potential, as oxidation leads to reduced device performance.
Compounds known in priort art for use as semiconductors are dithienothiophene (DTT) and its fused dimer &agr;,&agr;′-bis(dithieno[3,2-b:2′,3′-d]thiophene (BDT) having the structures shown below.
BDT and DDT are described for example in F. de Jong and M. J. Janssen, J. Org. Chem., 1971, 36, 12, 1645; S. Inaoka and D. M. Collard, J. Mater. Chem., 1999, 9, 1719; H. Sirringhaus et al, Appl. Phys. Lett. 1997, 71 (26), 3871; X-C. Li et al, J. Am. Chem. Soc., 1998, 120, 2206, and in the international patent application WO 99/12989.
In particular BDT, which has been extensively studied, has been shown to be an effective p-type semiconductor for organic FETs with a very high charge carrier mobility of 0.02-0.05 cm
2
/V. BDT also has been found in the solid state to have a completely coplanar formation, and to be more planar than oligomers of thiophene.
However, the materials described in prior art have several disadvantages. BDT has a high melting point and is very insoluble, therefore, if used as the active layer in an organic thin film transistor, it cannot be readily solution processed.
As a result, for applications like FETs, prior art materials like DTT or BDT are usually deposited as a thin film by vacuum deposition, which is an expensive processing technique that is unsuitable for the fabrication of large-area films.
It was an aim of the present invention to provide new organic materials for use as semiconductors or charge transport materials, which are easy to synthesize, have high charge mobility, good processibility. The materials should be easily processible to form thin and large-area films for use in semiconductor devices. Other aims of the invention are immediately evident to those skilled in the art from the following description.
It was found that these aims can be achieved by providing reactive thienothiophenes as described below.
Definition of Terms
The terms ‘liquid crystalline or mesogenic material’ or ‘liquid crystalline or mesogenic compound’ means materials or compounds comprising one or more rod-shaped, lath-shaped or disk-shaped mesogenic groups, i.e. groups with the ability to induce liquid crystal phase behavior. The compounds or materials comprising mesogenic groups do not necessarily have to exhibit a liquid crystal phase themselves. It is also possible that they show liquid crystal phase behavior only in mixtures with other compounds, or when the mesogenic compounds or materials, or the mixtures thereof, are polymerized.
The term ‘reactive group’ or ‘reactive compound’ includes compounds or groups that are capable of participating in a polymerization reaction, like radicalic or ionic chain polymerization, polyaddition or polycondensation, as well as compounds or groups that are capable of being grafted for example by condensation or addition to a polymer backbone in a polymeranalogous reaction.
The term ‘film’ includes self-supporting, i.e. free-standing, films that show more or less pronounced mechanical stability and flexibility, as well as coatings or layers on a supporting substrate or between two substrates.
SUMMARY OF THE INVENTION
One object of the invention are compounds of formula I
P—Sp—T—R I
wherein
P is a polymerizable or reactive group,
Sp is a spacer group or a single bond,
R is H, halogen, CN, NO
2
, an aliphatic, alicyclic or aromatic group with up to 40 C atoms that may also comprise one or more hetero atoms and one or more fused rings, or P—Sp—, and
T is a group comprising two or more fused thiophene rings.
Another object of the invention is the use of compounds of formula I as semiconductors or charge transport materials, in particular in optical, electrooptical or electronic devices, like for example components of integrated circuitry, field effect transistors (FET) for example as thin film transistors in flat panel display applications or for Radio Frequency Identification (RFID) tags, or in semiconducting components for organic light emitting diode (OLED) applications such as electroluminescent displays or backlights of flat panel displays, for photovoltaic or sensor devices, as electrode materials in batteries, as photoconductors and for electrophotographic applications.
Another object of the invention is a field effect transistor, for example as a component of integrated circuitry, as a thin film transistor in flat panel display applications, or in an RFID tag, comprising one or more compounds of formula I.
Another object of the invention is a semiconducting component, for example in OLED applications like electroluminescent displays or backlights of flat panel displays, in photovoltaic or sensor devices, as electrode materials in batteries, as photoconductors and for electrophotographic applications, comprising one or more compounds of formula I.
Another object of the invention is a security marking or device comprising an RFID or ID tag or a FET according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
The compounds of formula I provide several advantages over prior art materials
by adding substituent chains and other groups they can be made more soluble, thus being suitable for spin coating or solution coating techniques, rather than vacuum deposition, to prepare thin films for use e.g. in electronic devices such as transistors,
they can be made mesogenic or liquid crystalline, thus exhibiting a higher degree of order that leads to particularly high charge carrier mobility, in particular when being aligned in their mesophase into macroscopically ordered orientation
their macroscopic mesophase properties can be frozen in by in situ polymerization,
they combine the properties of a semiconducting material with those of a mesogenic material to give novel materials with a rigid, planar conjugated core and a flexible chain to increase solubility and to decrease the melting point, which show high charge carrier mobility when being aligned in their mesophase.
The compounds of formula I are useful as charge transport semiconductors, in that they have high carrier mobilities. In particular, the introduction of alkyl side chains to the thienothiophene core improves the solubility and therefore the solution processibility of the compounds of formula I.
Particularly preferred are mesogenic or liquid crystalline compounds of formula I, wherein T is a mesogenic group. These compounds are particu
Farrand Louise
Giles Mark
Goulding Mark
Heeney Martin
McCulloch Iain
Lambkin Deborah C.
Merck Patent Geselleshaft MIT Beschraenkter Haftung
Millen White Zelano & Branigan P.C.
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