Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
1998-11-19
2002-03-26
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S917000, C428S447000, C428S448000, C313S504000, C257S040000, C257S103000, C528S033000, C528S040000, C252S301350
Reexamination Certificate
active
06361885
ABSTRACT:
2 BACKGROUND OF THE INVENTION
2.1 Field of the Invention
The present invention relates to light-emitting materials and devices constructed using such materials. More specifically, the present invention relates to organic, electroluminescent materials and associated devices. The present invention has applications in the areas of materials science, organic chemistry, and electronics.
2.2 The Related Art
Makers of electronic devices that produce visual information, such as computers, are working intensely to develop lightweight display devices that provide brighter, sharper pictures at lower manufacturing cost. The drive to lighter, cheaper, better displays has lead to the development of flat-panel displays (“FPDs”) that are commonly used in laptop computers and include a growing share of the desktop computer display market. FPDs are almost exclusively liquid crystal displays (“LCDs”). However, LCD technology has shortcomings, including weak brightness and large power requirements.
One alternative to LCDs are electroluminescent (“EL”) displays. EL displays use the luminescense of a solid film that is produced when a voltage is applied to the solid film. Referring to
FIG. 1
, which illustrates the process generally, the electroluminescent material (“EML”) is placed between a cathode and an anode. The application of an electric potential (typically ~100 MV/m) injects holes into the highest occupied molecular orbital (“HOMO”) or valence band (“VB”) of the EML from the anode, and electrons are injected into the lowest unoccupied molecular orbital (“LUMO”) of the EML or conduction band (“CB”). The recombination of the electrons and holes in the EML causes the emission of light from EML.
To increase light output efficiency, a hole transport layer (“HTL”) and/or electron transport layer (“ETL”) are provided to increase the efficiency of hole (electron) injection and recombination in the EML. This has led to the design of EL displays having the general structure shown in
FIG. 2
at
200
. There, an electrode
202
is coupled with an electron transport layer
204
. ETL
204
is coupled with electroluminescent layer
206
, which, in turn, is coupled with hole transport layer
208
. HTL
208
is coupled with electrode
210
. Electrodes
202
and
210
are connected by contacts
212
and
214
that are each coupled to a source
216
.
Presently, EL displays are fabricated using either inorganic materials, such as manganese (Mn)-doped zinc sulfide (ZnS), or organic materials such as polyphenylene vinylene (“PPV”) and its derivatives. However, no satisfactory EL material has been developed for widespread applications. Although inorganic EL displays can provide high performance and durability, they suffer from large power requirements and expensive, low-throughput fabrication processes. Thus, inorganic EL displays have been relegated largely to niche applications, such as military and medical applications. Organic EL displays, on the other hand, can be fabricated more cheaply and simply than inorganic EL displays, but suffer from relatively poor performance.
Thus, a need remains to provide an EL display having a cost/performance profile that is suitable for the general marketplace. Such a device will require materials that are relatively inexpensive and simple to prepare compared to inorganic EL displays while providing comparable performance characteristics. The present invention meets these and other needs.
SUMMARY OF THE INVENTION
The present invention provides organic electroluminescent materials having desirable efficiency, weight, and durability properties, as well as devices made from such materials. The materials provided by the present invention are relatively straightforward to make, thereby being economically attractive. In addition, the light-emitting organic materials of the invention have been found to have performance characteristics comparable to inorganic light-emitting devices. Thus, the organic electroluminescent materials and devices of the invention will be appreciated by those of skill in the materials and electronics arts to address important needs in those fields.
In a first aspect, the present invention provides an electroluminescent device. The device of the invention includes, in one embodiment, an anode and a cathode. An organic electroluminescent material is electroluminescently conductively coupled directly with the anode and cathode such that the organic electroluminescent material emits light upon the application of a voltage across the anode and cathode. The organic electroluminescent material includes an organo-siloxane polymer. The main chain of the organo-siloxane polymer comprises an organic component that can be chosen from the group alkenyl, alkynyl, aralkyl, aryl, heteroaralkyl, and heteroaryl, and which can be substituted with hydrogen, alkyl, aryl, heteroalkyl, heteroaralkyl, nitro, cyano, hydroxy, alkoxy, aryloxy, thio, alkythio, arylthio, amino, halogen, dialkylamino, diarylamino, diaralkylamino, arylamino, alkylamino, arylalkylamino, carbonyloxy, carbonylalkoxy, carbonylalkyloxy, alkylcarbonyloxy, arylcarbonyloxy, alkoxylcarbonyloxy, sulfonyl, or sulfonyloxy. The organic component includes at least two covalent bonds coupling the organic component to the main chain of the organo-siloxane polymer.
In one embodiment, the organic component is selected from the group consisting of alkylene, aralkylene, arylene, heteroaralkylene, and heteroarylene. In a more specific embodiment, the organic component is arylene or heteroarylene, and, still more specifically, arylene. More particular embodiments include those for which the organic component comprises a polycyclic aromatic carbon network containing between 2 and 7 fused aromatic rings. Still more particular embodiments are those for which the polycyclic ring system is selected from the group consisting of electroluminescent agents, hole transport agents, electron transport agents, and combinations thereof.
In some embodiments, the organic component is a polycyclic aromatic carbon ring system that functions as an electroluminescent agent. In a more specific embodiment, the organic component comprises anthracene. In a still more specific embodiment, the anthracene is coupled with a silicon atom in the main chain of the organo-siloxane polymer by at least one alkyl group. In one embodiment, the alkyl group has the formula —CH
2
(CH
2
)
m
CH
2
—, where m is an integer between 0 and 4. In another more specific embodiment, the anthracene is coupled with the main chain of the organo-siloxane polymer by two such alkyl groups. The alkyl groups can be situated at two symmetric positions on the anthracene. A specific example of one such substituted anthracene is that for which m is 1 and the alkyl groups are located at the opposing central carbon atoms of the anthracene molecule: 9,10-bis(trimethylene)anthracene:
In another embodiment, the organic component comprises pentacene. In a still more specific embodiment, the pentacene is coupled with a silicon atom in the main chain of the organo-siloxane polymer by at least one alkyl group. In one embodiment, the alkyl group has the formula —CH
2
(CH
2
)
m
CH
2
—, where m is an integer between 0 and 4. In another more specific embodiment, the pentacene is coupled with the main chain of the organo-siloxane polymer by two such alkyl groups, which alkyl groups can be situated at symmetric positions on the carbon ring system. A specific example of one such substituted pentacene is that for which m is 1: 6,13-bis(trimethylene)pentacene:
The electroluminescent material can further include a dopant, such as an electron transport material, a hole transport material, or a dye. The electron transport material, hole transport material, or dye can be provided individually or in combination. In one embodiment, the hole transport material can be, without limitation, a porphyrin or aromatic tertiary amine. In another embodiment, the dye can be, without limitation, coumarin, a rhodamine salt (e.g., rhodamine perchlorate), or perylene. In still another embodiment, the organo-siloxane po
Organic Display Technology
Wallenstein & Wagner Ltd.
Yamnitzky Marie
LandOfFree
Organic electroluminescent materials and device made from... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Organic electroluminescent materials and device made from..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Organic electroluminescent materials and device made from... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2878874