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Patent Application Titled "Organic Electroluminescent Device" Published Online

June 12, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors CHEN, Chung-Chia (Hsin-Chu, TW); CHIN, Yuan-Chen (Hsin-Chu, TW); LIN, Chun-Liang (Hsin-Chu, TW), filed on October 17, 2013, was made available online on May 29, 2014.

The assignee for this patent application is Au Optronics Corp.

Reporters obtained the following quote from the background information supplied by the inventors: "Organic electroluminescent device, such as organic light emitting diodes (OLED), having characteristics of high brightness, rapid response time, thin and small in size, light weight, full color and providing self luminance as well as advantages of low power consumption, high luminescent efficiency, environmental friendly, and low heat emission, are considered as a next-generation display and lighting device.

"Typically, an organic electroluminescent device comprises a transparent substrate, a transparent electrode (anode), a hole transport layer, an organic light emitting layer, an electron transport layer and a metal layer (cathode). When a positive bias is imposed on the organic electroluminescent device, electrons and holes are injected into the light emitting layer respectively from the cathode and the anode, and excitons are generated due to electron and hole mobility triggered by the potential difference of the external electric field, whereby light is emitted from the while portions of excitons in an excited state decay to a ground state.

"However, since the organic light emitting layer has a refractive index substantially greater than that of the substrate, typically made of glass, and the refractive index of substrate is also greater than air, thus total internal reflection of light emitting from the organic light emitting layer occurs at the interfaces of these layers among the organic electroluminescent device, and mere a few light emitting from the organic light emitting layer penetrates through the glass substrate and the transparent electrode. Exemplarily, almost 80% of light emitting from the organic light emitting layer would be limited in the organic electroluminescent device. Therefore, there is a need of providing an improved organic electroluminescent device to extract the light from the organic light emitting layer more effectively to obviate the drawbacks encountered from the prior art."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "In accordance with one aspect, the present invention provides an organic electroluminescent device comprises a substrate, a first optical structure, a transparent electrode, an organic light emitting structure, a reflecting layer and a second optical structure. The substrate has a first surface and a second surface. The first optical structure is disposed on the first surface and has a first haze. The transparent electrode is disposed on the first optical structure. The organic light emitting structure is disposed on the transparent electrode. The reflecting layer is disposed on the organic light emitting structure. The second optical structure is disposed on the second surface and has a second haze, wherein the first haze is less than the second haze.

"In one embodiment of the present invention, the first haze and the second haze has a numerical difference substantially greater than or equal to 10. In one embodiment of the present invention, the first haze ranges from 30% to 80%. In one embodiment of the present invention, the second haze ranges from 50% to 90%.

"In one embodiment of the present invention, the second optical structure is a bulk scattering element, a surface scattering element, a micro-lens structure or the arbitrary combinations thereof.

"In one embodiment of the present invention, the first optical structure is a bulk scattering element, a surface scattering element, a micro-lens structure or the arbitrary combinations thereof.

"In one embodiment of the present invention, the first optical structure is a bulk scattering element comprising a composite material layer and a plurality of particles spread in the composite material layer, wherein the particles have an average diameter substantially ranging from 200 nm to 1100 nm.

"In one embodiment of the present invention, the composite material layer and the particles has a refractive index difference substantially greater than 0.2.

"In one embodiment of the present invention, the first optical structure is a surface scattering element comprising a plurality of particles with various diameters and a particle fixing layer used to fix the particles on the first surface of the substrate.

"In one embodiment of the present invention, the organic electroluminescent device further comprises a planarization layer disposed between the surface scattering element and the transparent electrode.

"In accordance with the aforementioned embodiments of the present invention, an organic electroluminescent device with high light extraction efficiency comprising a substrate, a first optical structure with a first haze, a transparent electrode, an organic light emitting structure, a reflecting layer and a second optical structure with a second haze is provided, wherein the first optical structure and the second optical structure are respectively disposed on opposite surfaces of the substrate; the transparent electrode is disposed on the first optical structure; the organic light emitting structure is disposed on the transparent electrode; the reflecting layer is disposed on the organic light emitting structure; and the first haze is less than the second haze. By optimizing the haze difference between the first optical structure and the second optical structure, a synergistic effect for extracting light emitting from the organic electroluminescent device may occur. Accordingly, the light extraction efficiency of the organic electroluminescent device can be significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS

"The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:

"FIG. 1 is a cross-sectional view of an organic electroluminescent device in accordance with one embodiment of the present invention; and

"FIG. 2 is a cross-sectional view of an organic electroluminescent device in accordance with another embodiment of the present invention."

For more information, see this patent application: CHEN, Chung-Chia; CHIN, Yuan-Chen; LIN, Chun-Liang. Organic Electroluminescent Device. Filed October 17, 2013 and posted May 29, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5275&p=106&f=G&l=50&d=PG01&S1=20140522.PD.&OS=PD/20140522&RS=PD/20140522

Keywords for this news article include: Au Optronics Corp.

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Source: Politics & Government Week


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