Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
2001-01-26
2004-07-20
Noori, Max (Department: 2855)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
Reexamination Certificate
active
06765348
ABSTRACT:
COPENDING APPLICATIONS
Illustrated in copending applications U.S. Ser. No. 09/770,159, filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, is an organic light emitting device, comprising in an optional sequence
(i) a substrate;
(ii) a first electrode;
(iii) a mixed region comprising a mixture of a hole transport material and an electron transport material, and wherein this mixed region includes at least one organic luminescent material;
(iv) a second electrode;
(v) a thermal protective element coated on the second electrode; wherein one of the two said electrodes is a hole injection anode, and one of the two said electrodes is an electron injection cathode, and wherein the organic light emitting device further comprises;
(vi) a hole transport region, interposed between the anode and the mixed region, wherein the hole transport region optionally includes a buffer layer; and
(vii) an electron transport region interposed between the second electrode and the mixed region; and U.S. Pat. No. 6,479,172, the disclosure of which is totally incorporated herein by reference, is an electroluminescent device comprised of a first electrode, an organic electroluminescent element, and a second electrode wherein said electroluminescent element contains a fluorescent hydrocarbon component of Formula (I)
wherein R
1
and R
2
are substituents selected from the group consisting of hydrogen, an alkyl, an alicyclic alkyl, an alkoxy, a halogen, and a cyano; Ar
1
and Ar
2
are each independently an aromatic component or an aryl group comprised of a from about 4 to about 15 conjugate-bonded or fused benzene rings.
The mixed region, the hole transport region including the buffer layer, and the electron transport region reduce changes in device luminance and/or driving voltage during device operation, and enable stability in the device luminance and/or driving voltage during device operation for extended periods of time at elevated temperatures, while the thermal protective coating increases the device resistance to shorting at elevated temperatures, and thus improves the thermal durability of the organic EL device.
Illustrated in U.S. Pat. No. 6,492,339 on “Organic Light Emitting Devices Having Improved Efficiency and Operation Lifetime”, filed on Jul. 20, 1999, and U.S. Pat. No. 6,392,250 on “Organic Light Emitting Devices Having Improved Performance”, filed on Jun. 30, 2000, the disclosures of which are totally incorporated herein by reference, are organic light emitting devices (organic EL devices) that, for example, comprise a mixed region including a mixture of a hole transport material and an electron transport material. At least one of a hole transport material region and an electron transport material region can be formed on the mixed region. The stability of the above mentioned organic EL devices disclosed in U.S. Pat. No. 6,392,339 and U.S. Pat. No. 6,392,250 is usually reduced at temperatures above 80° C. due, it is believed, to a decrease in the device resistance to shorting and also since, it is believed, to a progressive increase in the driving voltage required to drive a certain current through the organic EL devices. As a result, the operational stability of these devices can be limited to a few hundred hours or less at these high temperatures, and more specifically, at high temperatures in the range of from about 80° C. to about 100° C. Therefore, these devices are believed to be unsatisfactory in some instances, for applications in which there is desired an operational stability of the organic EL device of at least, for example, several thousand hours at temperatures of, for example, 90° C., such as, for example, in some automotive, military or other industrial applications where durability in harsh conditions is necessary.
Also, illustrated in copending U.S. Ser. No. 09/629,163 (D/A0057) on “Annealed Organic Light Emitting Devices And Methods Of Annealing Organic Light Emitting Devices”, filed Jul. 31, 2000, the disclosure of which is totally incorporated herein by reference, is a thermal annealing method and also annealed organic light emitting devices wherein the device performance is improved by means of thermal annealing.
The appropriate components and processes of the above copending applications may be selected for embodiments of the present invention.
BACKGROUND OF THE INVENTION
This invention relates to optoelectronic devices and, more particularly, to organic light emitting, or organic electroluminescent (EL) devices. More specifically, the present invention relates to stable organic EL devices, and which devices do not substantially degrade, or possess minimum degradation at, for example, high temperatures, such as 100° C., and moreover devices which are not substantially adversely affected by high temperatures. The organic EL devices according to the present invention can be used for various applications, and are especially useful in high temperature technological applications that usually require operating, storing, and/or heating the organic EL device at temperatures above 25° C., and more specifically, at temperatures in the range of about 60° C. to about 100° C.
PRIOR ART
Tang and Van Slyke disclose electroluminescent devices, reference C. W. Tang and S. A. Van Slyke, “Organic Electroluminescent Diodes,”
Appl. Phys. Lett.
51, pp. 913-915, 1987. Since this publication, organic light emitting devices (OLEDs) have attracted attention because of their potential for use in the fabrication of large-area displays, reference J. R. Sheats et al, “Organic Electroluminescent Devices,”
Science
273, pp. 884-888, 1996; J. Salbeck, “Electroluminescence with Organic Compounds,”
Ber. Bunsenges. Phys. Chem.
100, pp. 1667-1677, 1996; and Z. Shen et al., “Three-Color, Tunable, Organic Light-Emitting Devices,”
Science
276, pp. 2009-2011,1997.
In general, the structure of an EL device
10
is illustrated in FIG.
1
. The EL device
10
includes a substrate
12
composed of, for example, glass; a first electrode
14
on the substrate
12
; a second electrode
16
; and interposed between the first electrode
14
and the second electrode
16
a light emitting region
18
formed of at least one layer comprising an organic luminescent material, such as, for example, a metal oxinoid compound, a stilbene compound, an anthracite compound, a polyfluorene, or a poly(p-phenylenevinylene). One of the electrodes includes a layer comprising at least one material with a high work (typically >4.0 eV), such as, for example, indium tin oxide (ITO) and functions as an anode, whereas the other electrode includes a layer comprising at least one material with a low work function (typically <4 eV), which can be a metal (such as, for example, Ca or Al), a metal alloy (such as, for example, Mg:Ag or Al:Li) or a metal compound (such as, for example, an alkaline metal halides or oxides), and which functions as a cathode. During operation, an applied electric field causes positive charges (holes) to be injected from the anode, and negative charges (electrons) to be injected from the cathode to recombine in the light emitting region
18
and thereby produce light emission.
A problem common to this type of known organic EL devices is poor thermal stability which usually renders the EL device unsuitable for technological applications that require high durability of devices at high temperatures, and which temperatures are, for example, above about 60° C., and specifically, temperatures in the range of about 70° C. to about 100° C. At these high temperatures, device shorting often occurs leading to high leakage currents, thus rendering the organic EL devices nonfunctional (reference, for example, Zhou et al., “Real-time observation of temperature rise and thermal breakdown processes in organic LEDs using an IR imaging and analysis system”,
Advanced Materials
12, pp 265-269, 2000).
Therefore, there is a need to prevent or, at least, to significantly reduce, or minimize the likelihood of the aforementioned prior art shorting of the organic EL device. This advan
Aziz Hany
Hu Nan-Xing
Popovic Zoran D.
Noori Max
Palazzo E. O.
LandOfFree
Electroluminescent devices containing thermal protective layers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electroluminescent devices containing thermal protective layers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electroluminescent devices containing thermal protective layers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3256912