Active solid-state devices (e.g. – transistors – solid-state diode – Organic semiconductor material
Reexamination Certificate
2001-06-28
2003-12-02
Lee, Eddie (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Organic semiconductor material
C257S079000
Reexamination Certificate
active
06657224
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
BACKGROUND OF THE INVENTION
Organic electroluminescent devices also known as organic light emitting diode (“OLED”) devices comprise an anode, a cathode and an electroluminescent medium made up of extremely thin layers (typically less than 1.0 micrometer in combined thickness) separating the anode and the cathode. A basic two-layer light emitting diode comprises one organic layer that is specifically chosen to inject and transport holes and a second organic layer that is specifically chosen to inject and transport electrons. The interface between the two layers provides an efficient site for the recombination of the injected hole-electron pair, which results in electroluminescence. The electroluminescent medium can comprise additional layers, including, but not limited to, an emitter layer between the hole injection and transport and the electron injection and transport layers in which recombination of holes and electrons occurs. Since light emission is directly related to current density through the organic electroluminescent medium, the thin layers coupled with increased charge injection and transport efficiencies have allowed acceptable light emission levels (e.g., brightness levels capable of being visually detected in ambient light) to be achieved with low applied voltages in ranges compatible with integrated circuit drivers, such as field effect transistors.
A large variety of organic compounds having the appropriate characteristics can be used in the layers of the electroluminescent medium. For example, variations in the chemical structures of compounds in the various layers can result in changes in ionization potential, mobility of holes or electrons, or the wavelength of emitted light. Nevertheless, the performance of OLEDs may be limited by the organic materials, rendering them undesirable for many applications.
Hole-injection and hole-transport organic compounds have tended to be an unstable part of the electroluminescent medium of OLEDs. These materials are thought to undergo a morphological change when exposed to increased temperatures or when stored for long periods of time. Since efficient operation of the hole-injection and hole-transport layers depends on their amorphous nature, morphological changes may lead to degradation of the OLED. The temperature at which morphological changes occur and an amorphous material becomes crystalline is the glass transition temperature of the material. The glass transition temperature of hole-injection and hole-transport compounds has generally been below 100° C.
Triarylamine derivatives such as N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) and N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPD) are the most widely used derivatives in the hole injection and hole transport layers of OLEDs (Tang et al. (1987)
Appl. Phys. Let.
51:913-15; Mitschke et al. (2000)
J. Mater. Chem.
10:1471-1507). However, these triarylamines tend to crystallize on aging or if left at ambient temperatures. Improvements to the stability of hole-injection and hole-transport materials have been made, including inserting a triarylamine derivative into a polymer matrix or covalently attaching triarylamines to a polymer backbone (Mitschke et al. (2000)). In addition, hole-transport and hole-injection materials, such as the “starburst amines,” have been designed that have higher glass transition temperatures (Kurwabara et al. (1994)
Adv. Mater.
6:677; JP 07997305 to Shirota et al; EP 00508562 A1 to Shirota et al.; JP 09012548 to Shirota et al.; JP 08291115 to Shirota et al.; and JP 06312979 to Shirota et al).
Discussion or citation of a reference herein shall not be construed as an admission that such reference is prior art to the present invention.
BRIEF SUMMARY OF THE INVENTION
In a first embodiment, the present invention relates to an organic light emitting diode device comprising: (a) a cathode; (b) an anode; and (c) at least two organic layers between the anode and the cathode, wherein the at least two organic layers comprise a first organic layer formed from at least one electron-injection/electron-transport material and a second organic layer formed from at least one hole-injection/hole-transport material, wherein the electron-injection/electron-transport material is adjacent to the cathode and the hole-injection/hole-transport material is adjacent to the anode, the at least one hole-injection/hole-transport material comprising a compound of formula 1:
wherein R
1
is selected from the group consisting of biphenyl, naphthyl, phenyl and
Q is selected from the group consisting of a bond, C
1
-C
4
alkyl, —C(O)—, —S(O)—, —O—Si—O—, —O—Ge—O—, —O—,
and
R
2
and R
3
are each independently selected from the group consisting of aryl, F, Cl, —CF
3
, saturated alkyl of up to 10 carbon atoms, SO
2
R
6,
Si(R
6
)
3
, and OR
6
, or R
2
and R
3
taken together form a heterocyclic ring of up to 8 atoms, wherein one of the 8 atoms is nitrogen and another of the 8 atoms is either nitrogen or oxygen, or R
2
and R
3
taken together with the phenyl group to which they are attached form a fused polycyclic aromatic system, wherein the fused polycyclic aromatic system comprises up to 16 carbon atoms;
R
4
and R
5
are each independently selected from the group consisting of:
or R
4
and R
5
taken together with the nitrogen to which they are attached are selected from the group consisting of:
R
6
is C
1
-C
4
straight or branched saturated alkyl;
R
7
and R
8
are each independently selected from the group consisting of —OR
9
, C
1
-C
4
alkyl, aryl, —SCH
3
, —CF
3
, —Cl, —Br, —NO
2
, and —COOR
9
;
R
9
is selected from the group consisting Of C
1
-C
6
alkyl and aryl; and
wherein one of the bottom electrode and the top electrode is a cathode and the other is an anode.
In a second embodiment, the present invention relates to an organic light emitting diode device comprising: (a) a cathode; (b) an anode; (c) a layer formed from at least one electron-injection/electron-transport material that is adjacent to the cathode; (d) a hole-injection layer that is adjacent to the anode; and (e) at least one hole-transport layer that is adjacent to the hole-injection layer, wherein at least one of the hole-injection and hole-transport layers comprises a compound of formula 1, wherein one of the bottom electrode and the top electrode is a cathode and the other is an anode.
In a third embodiment, the present invention relates to an organic light-emitting diode device that emits green light, comprising: (a) a bottom electrode that is an anode comprising indium tin oxide; (b) a hole-injection layer adjacent to the anode comprising bis(N,N′-1-naphthyl-phenyl-amino-biphenyl)-biphenyl amine (BPA-DNPB); (c) a hole-transport layer adjacent to the hole-injection layer comprising bis(carbazol-N-biphenyl)-biphenyl amine (BPA-BCA); (d) an emitter layer adjacent to the hole-transport layer comprising tris(hydroxyquinoline) aluminum (ALQ) and a compound selected from the group consisting of Coumarin 6, Coumarin 485, Coumarin, 487, Coumarin 490, Coumarin 498, Coumarin 500, Coumarin 503, Coumarin 504, Coumarin 504T, Coumarin 510, Coumarin 515, Coumarin 519, Coumarin 521, Coumarin 521T, Coumarin 522B, Coumarin 523, Coumarin 525, Coumarin 535, Coumarin 540A, Coumarin 545, and mixtures thereof; (e) an electron-transport layer adjacent to the emitter layer comprising ALQ; and (f) a top electrode that is a cathode comprising lithium fluoride and aluminum or magnesium and silver.
In a fourth embodiment, the present invention relates to an organic light-emitting diode device that emits white or blue light, comprising: (a) a bottom electrode that is an anode comprising indium tin oxide; (b) a hole-injection layer adjacent to the anode comprising BPA-DNPB; (c) a hole-transport layer adjacent to the hole-injection layer comprising BPA-BCA; (d) an emitter layer adjacent to the hole-transport layer comprising DCJTB, IDE-120 and IDE-102; (e) an electron-
Shi Xiaobo
Sokolik Igor
Bazerman & Drangel PC
Brock II Paul E
eMagin Corporation
Lee Eddie
LandOfFree
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