Conjugated polymers containing 2,7 fluorenyl units with...

Details Conjugated polymers containing 2,7 fluorenyl units with... Conjugated polymers containing 2,7 fluorenyl units with...

2001-05-02

2003-04-01

Truong, Duc (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From boron-containing reactant

C528S008000, C528S397000, C528S488000, C252S301160, C252S301350

Reexamination Certificate

active

06541602

ABSTRACT:

There is considerable industrial demand for large-area solid-state light sources for a number of applications, predominantly in the area of display elements, display-screen technology and illumination technology. The requirements made of these light sources cannot at present be completely satisfied by any of the existing technologies.
As an alternative to conventional display and illumination elements, such as incandescent lamps, gas-discharge lamps and non-self-illuminating liquid-crystal display elements, electroluminescent (EL) materials and devices, such as light-emitting diodes (LEDs), have already been in use for some time.
Besides inorganic electroluminescent materials and devices, low-molecular-weight, organic electroluminescent materials and devices have also been known for about 30 years (see, for example, U.S. Pat. No. 3,172,862). Until recently, however, such devices were greatly limited in their practical applicability.
WO 90/13148 and EP-A-0 443 861 describe electroluminescent devices which contain a film of a conjugated polymer as light-emitting layer (semiconductor layer). Such devices offer numerous advantages, such as the possibility of manufacturing large-area, flexible displays simply and inexpensively. In contrast to liquid-crystal displays, electroluminescent displays are self-illuminating and therefore do not require an additional illumination source at the back.
A typical device in accordance with WO 90/13148 consists of a light-emitting layer in the form of a thin, dense polymer film (semiconductor layer) containing at least one conjugated polymer. A first contact layer is in contact with a first surface, and a second contact layer is in contact with a further surface of the semiconductor layer. The polymer film of the semiconductor layer has a sufficiently low concentration of extrinsic charge carriers so that, on application of an electric field between the two contact layers, charge carriers are introduced into the semiconductor layer, the first contact layer becoming positive compared with the other layer, and the semiconductor layer emits radiation. The polymers used in such devices are conjugated. The term “conjugated polymer” is taken to mean a polymer which has a delocalized electron system along the main chain. The delocalized electron system gives the polymer semiconductor properties and enables it to transport positive and/or negative charge carriers with high mobility.
For use in EL elements as described in WO 90/13148, very many different polymers have already been proposed. Derivatives of poly(p-phenylenevinylene) (PPV) appear particularly suitable. Such polymers are described, for example, in WO 98/27136. These polymers are particularly suitable for electroluminescence in the green to red spectral region. In the blue to blue-green spectral region, the polymers proposed hitherto are principally those based on poly-p-phenylene (PPP) or polyfluorene (PF). Corresponding polymers are described, for example, in EP-A-0 707 020, WO 97/05184 and WO 97/33323. These polymers already exhibit good EL properties, although development is still not complete by far. Thus, polymers in the blue to blue-green spectral region frequently also exhibit the phenomenon of morphological instability. For example, many polyfluorenes exhibit liquid-crystalline or related behavior, which can result, in thin films, in domain formation, which is in turn unsuitable for the production of a homogeneously luminous area. These polymers also tend to form aggregates, which shifts the electroluminescence into the long-wave region in an undesired manner, and adversely affects the life of the EL elements.
The object of the present invention was therefore to provide polymers which are suitable for emission in the blue and blue-green spectral region and at the same time have improved morphological behavior.
Surprisingly, it has now been found that incorporation of specific comonomers in otherwise typically linear conjugated polymers principally containing 2,7-fluorenyl units significantly improves the morphological properties without losing the very good applicational properties (emission color, quantum yield of the emission, suitability for EL applications). A similar proposal is described in M. Kreyenschmidt et al., Macromolecules 1998, 31, 1099, where it was attempted to increase the morphological stability of polyfluorenes by incorporation of comonomers. However, good results (regarding the morphology) were only found for comonomers which result in interruption of conjugation. However, these interruptions result in general problems (for example lower charge-carrier mobility) when such polymers are used in electronic applications, for example EL devices.
The polymers according to the invention contain randomly or regularly copolymerized comonomer units, which firstly allow electronic conjugation of the entire polymer and secondly cause the polymer to kink in its main chain. For the purposes of the present application, the term “kink along the main polymer chain” is taken to mean that if the polymer containing principally 2,7-fluorenyl units is regarded as a linear rod, the kink causes a significant deviation from linear, i.e. if the longitudinal axis of the 2,7-fluorenyl units is regarded as a straight line, these two units adjacent to the kink have an angle at the intersection which differs significantly from 180° (or 0°); however, the formal conjugation of the polymer is not interrupted here.
The invention relates to conjugated polymers which, besides structural units of the formula (I)
in which
R
1
and R
2
are identical or different and are hydrogen, C
1
-C
22
-alkyl, C
2
-C
20
-heteroaryl, C
5
-C
20
-aryl, F, Cl or CN, where the abovementioned alkyl radicals can be branched or unbranched or alternatively can be cycloalkyl radicals, and individual, non-adjacent CH
2
groups of the alkyl radical can be replaced by O, S, C═O, COO, N—R
5
or simple aryl radicals, where the abovementioned aryl radicals can be substituted by one or more substituents R
3
. Preference is given to compounds in which R
1
and R
2
are both identical and are not hydrogen or chlorine. Preference is furthermore given to compounds in which R
1
and R
2
are different from one another and are also not hydrogen,
R
3
and R
4
are identical or different and are C
1
-C
22
-alkyl, C
2
-C
20
heteroaryl, C
5
-C
20
-aryl, F, Cl, CN, SO
3
R
5
or NR
5
R
6
, where the alkyl radicals can be branched or unbranched or alternatively can be cycloalkyl radicals, and individual, non-adjacent CH
2
groups of the alkyl radical can be replaced by O, S, C═O, COO, N—R
5
or simple aryl radicals, where the abovementioned aryl radicals can be substituted by one or more non-aromatic substituents R
3
,
R
5
and R
6
are identical or different and are H, C
1
-C
22
-alkyl, C
2
-C
20
-heteroaryl or C
5
-C
20
-aryl, where the alkyl radicals can be branched or unbranched or alternatively can be cycloalkyl radicals, and individual, non-adjacent CH
2
groups of the alkyl radical can be replaced by O, S, C═O, COO, N—R
5
or simple aryl radicals, where the abovementioned aryl radicals can be substituted by one or more non-aromatic substituents R
3
, and
m and n are each an integer 0, 1, 2 or 3, preferably 0 or 1,
also contain structural units of the formula (II)
in which
Ar is a mono- or polycyclic aromatic conjugated system having 5 to 20 carbon atoms, in which one or more carbon atoms can be replaced by nitrogen, oxygen or sulfur and whose linking points are selected so that an angle not equal to 1800, preferably less than 120°, particularly preferably less than 90°, is formed along the main polymer chain.
Particularly suitable radicals Ar (aromatic) are those which, besides the abovementioned kink, also produce a spatial twist of the main polymer chain. This is achieved if the three individual polymers connected by two consecutive kinks cannot be brought into a plane (i.e. a dihedral angle of significantly greater than 0° results).
The polymer according to invention contains at least 1 mol %, preferably from 2 mol %

Affiliated with

Also associated with

Rating

Conjugated polymers containing 2,7 fluorenyl units with... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Conjugated polymers containing 2,7 fluorenyl units with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Conjugated polymers containing 2,7 fluorenyl units with... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3043413