Electro luminescent device comprising fluorene compounds

Details Electro luminescent device comprising fluorene compounds Electro luminescent device comprising fluorene compounds

2001-05-01

2003-07-01

Kelly, Cynthia H. (Department: 1774)

Stock material or miscellaneous articles

Composite

Of inorganic material

C428S917000, C313S506000, C313S504000, C564S427000, C564S428000, C564S434000, C548S440000

Reexamination Certificate

active

06586120

ABSTRACT:

BACKGROUND
Organic light emitting diodes (OLEDs) are attractive due to their potential use in a wide range of lightings as well as high and low resolution display applications. The simplest OLED device contains an organic emission layer sandwiched between two electrodes that inject electrons and holes. The electrons and holes meet in the organic emission layer and produce light. Multiple layers between the two electrodes can make the light production more efficient (Tang et al. (1987)
Applied Physics Letters
51: 913-915, and Burroughs et al. (1990)
Nature
347: 539). The multiple layers may include one or more electron transport layers, and one or more hole transport layers. See Adachi et al. (1988)
Japanese Journal of Applied Physics
27: L269-L271, and Mitschke and Bäuerle (2000)
J. Mater. Chem.
10: 1471-1507.
SUMMARY
This invention relates to compounds useful as a hole transport material in an OLED device.
In one aspect, the present invention features a fluorene compound having the formula:
Each of R
1
-R
4
, R
5
-R
8
, and R
5
-R
8
, independently, is H, halogen, CN, NO
2
, amino, alkylamino, arylamino, dialkylamino, diarylamino, hydroxyl, alkoxyl, aryloxyl, heteroaryloxyl, mercapto, alkylthio, arylthio, heteroarylthio, alkyl, aryl, heteroaryl, or heterocyclyl; each of A and B, independently, is phenyl, naphthyl, or phenanthryl; and each of R
9
and R
10
, independently, is H, aryl, heteroaryl, aryloxyl, or heteroaryloxyl; provided that if both A and B are phenyl, then one of R
9
and R
10
is not H. Note that if each of R
5
-R
8
is the same as each of R
5′
-R
8′
, correspondingly, the compounds of this invention are symmetrical. Further, R
9
or R
10
can be substituted at any suitable position on ring B or A. A subset of the compounds encompassed by the above formula are featured by that each of R
9
and R
10
, independently, is H, aryl, or heteroaryl. In these compounds, each of A and B, independently, can be phenyl or naphthyl, and each of R
1
-R
4
, R
5
-R
8
, and R
5′
-R
8′
, independently, is H, dialkylamino, diarylamino, alkyl, aryl, or heteroaryl.
Alkylamino, arylamino, dialkylamino, diarylamino, alkoxyl, aryloxyl, heteroaryloxyl, alkylthio, arylthio, heteroarylthio, alkyl, aryl, heteroaryl, heterocyclyl, phenyl, naphthyl, and phenanthryl mentioned above include both substituted and unsubstituted moieties. The term “substituted” refers to one or more substituents (which may be the same or different), each replacing a hydrogen atom. Examples of substituents include, but are not limited to, halogen, amino, alkylamino, arylamino, dialkylamino, diarylamino, hydroxyl, mercapto, cyano, nitro, C
1
~C
6
alkyl, C
1
~C
6
alkenyl, C
1
~C
6
alkoxy, aryl, heteroaryl, or heterocyclyl, wherein alkyl, alkenyl, alkoxy, aryl, heteroaryl, and heterocyclyl are optionally substituted with C
1
~C
6
alkyl, halogen, amino, alkylamino, arylamino, dialkylamino, diarylamino, hydroxyl, mercapto, cyano, or nitro. The term “aryl” refers to a hydrocarbon ring system having at least one aromatic ring. Examples of aryl moieties include, but are not limited to, phenyl, naphthyl, and pyrenyl. The term “heteroaryl” refers to a hydrocarbon ring system having at least one aromatic ring which contains at least one heteroatom such as O, N, or S. Examples of heteroaryl moieties include, but are not limited to, pyridinyl, carbazolyl, and indolyl.
One exemplary compound of this invention is 9,9-bis{4-[di-(p-biphenyl)aminophenyl]}fluorene (BPAPF):
Also within the scope of this invention is an electro-luminescence device made with one or more of the fluorene compounds described above. The device includes an anode layer; a hole transport layer that can include the fluorene compounds of this invention; an electron transport layer; and a cathode layer. The anode, the hole transport layer, the electron transport layer, and the cathode are disposed in the above order.
The details of one or more embodiments of the invention are set forth in the description below. Other features, objects, and advantages of the invention will be apparent from the description and from the claims.
DETAILED DESCRIPTION
This invention relates to fluorene compounds and their use as a hole transport material in an electro-luminescence device.
The fluorene compounds of this invention can be prepared by methods well known to a skilled person in the art, including the synthetic routes disclosed herein.
For example, shown below is a scheme that depicts synthesis of a symmetrical compound (right) and an asymmetrical compound (left) from a starting material such as fluorenone:
More specifically, a symmetrical compound can be synthesized by the following method: A mixture containing a fluorenone and an aniline is refluxed in the presence of an acid catalyst to produce an intermediate 9,9-bis(aminophenyl)fluorene. The intermediate is subsequently reacted with aryl halides (Ar—X and Ar′—X, stepwise) in the presence of a catalyst such as palladium to obtain the desired symmetrical product. An asymmetrical compound, on the other hand, can be synthesized as follows: A reaction mixture containing a fluorenone and two different anilines (e.g., an aniline and a 2-fluoroaniline as shown in the above scheme) is refluxed in the presence an acid catalyst to produce a mixture including an asymmetric fluorene intermediate. The asymmetric fluorene intermediate is then reacted with aryl halides (Ar—X and Ar′—X, stepwise) in the presence of a catalyst such as palladium to produce the desired asymmetrical product.
As another example, a scheme below depicts synthesis of other compounds of this invention from a different starting material such as a dinitro-substituted fluorenone:
2,7-Bis(diarylamino)-9,9-bis(diarylaminophenyl)fluorene, a compound of this invention, can be synthesized according to the above synthetic route as follows: A mixture of a 2,7-dinitrofluorenone and an aniline is refluxed in the presence of an acid catalyst to give an intermediate 2,7-dinitro-9,9-bis(aminophenyl)fluorene. The two nitro groups are then converted to two amino groups by a reduction reaction with Fe/NH
4
Cl. Finally, the reduced intermediate is reacted with aryl halides (Ar—X and Ar′—X, stepwise) in the presence of a catalyst such as palladium to produce the desired product.
BPAPF can be prepared by the method described above. It can also be prepared as follows: A reaction mixture containing commercially available 9, 9-bis(4-aminophenyl)fluorene and 4-bromobiphenyl in toluene is refluxed for 20 hr in the presence of a catalytic amount of Pd
2
(dba)
3
, 1,10-phenanthroline, and potassium hydroxide. After cooling, the reaction mixture is filtered and washed with H
2
O and ethyl acetate. The solid is collected and purified by sublimation.
The compounds of the invention can be used as a hole transport material in an electro-luminescence device.
Typically, the electro-luminescence device can be classified as a two-layer structured device or a three-layer structured device. A two-layer structured device can include a hole transport layer and an electron transport layer, both of which are sandwiched between a pair of electrodes. The electron transport layer can function as a luminescent layer, which transports electrons and emits lights (Tang et al., (1989)
J. Appl. Phys.
65: 3610). Generally, a hole transport layer, an electron transport layer, and a cathode layer are deposited sequentially in the above order. The anode layer can be formed on a substrate, such as a glass. A three-layer structured device can include an anode layer, a hole transport layer, a luminescent layer and an electron transport layer, and a cathode layer in the above order. The luminescent layer can be another hole transport or another electron transport layer.
Optionally, the electro-luminescence device can include a dopant-containing layer, which can be an electron transport layer or a luminescent layer. The dopant-containing layer can also be located within the electron transport layer or the luminescent layer, or can be sandwiche

Affiliated with

Also associated with

Rating

Electro luminescent device comprising fluorene compounds does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electro luminescent device comprising fluorene compounds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electro luminescent device comprising fluorene compounds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3037827