Source: http://www.google.com/patents/US7285910?dq=5893120
Timestamp: 2017-01-20 23:29:36
Document Index: 160143299

Matched Legal Cases: ['Application No. 2002', 'art 155', 'art 155', 'Application No. 10', 'art 255', 'art 255']

Patent US7285910 - Organic electroluminescence device for preventing current leakage and ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA method of fabricating an organic electroluminescent display by forming a lower electrode on a substrate and forming an insulating film with an opening part for exposing a portion of the lower electrode. An organic thin film is formed on the substrate and a surface of a portion of the organic thin film...http://www.google.com/patents/US7285910?utm_source=gb-gplus-sharePatent US7285910 - Organic electroluminescence device for preventing current leakage and improving inkjet-printing qualityAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS7285910 B2Publication typeGrantApplication numberUS 10/683,286Publication dateOct 23, 2007Filing dateOct 14, 2003Priority dateNov 4, 2002Fee statusPaidAlso published asCN1499902A, CN100346481C, DE10352515A1, DE10352515B4, US20040085014Publication number10683286, 683286, US 7285910 B2, US 7285910B2, US-B2-7285910, US7285910 B2, US7285910B2InventorsJoon Young Park, Jae Jung KimOriginal AssigneeSamsung Sdi Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (21), Referenced by (6), Classifications (26), Legal Events (6) External Links: USPTO, USPTO Assignment, EspacenetOrganic electroluminescence device for preventing current leakage and improving inkjet-printing quality
US 7285910 B2Abstract
A method of fabricating an organic electroluminescent display by forming a lower electrode on a substrate and forming an insulating film with an opening part for exposing a portion of the lower electrode. An organic thin film is formed on the substrate and a surface of a portion of the organic thin film layer is selectively treated. A luminescent layer is formed on another portion of the organic thin film layer; and an upper electrode is formed on the front of the substrate.
a lower electrode, a hole transport layer, a luminescent layer and an upper electrode sequentially formed on a substrate, wherein a portion of the hole transport layer corresponding to the lower electrode has a surface characteristic and a resistance value different from a portion of the hole transport layer other than the portion corresponding to the lower electrode; and
an insulating film formed on the substrate so that a portion of the lower electrode is exposed,
wherein the portion of the hole transport layer corresponding to the lower electrode is hydrophilic,
wherein the portion of the hole transport layer other than the portion corresponding to the lower electrode is hydrophobic, and
wherein the insulating film is a planarization film with a bank film formed thereon.
an insulating film formed on the substrate so that a portion of the lower electrode is exposed;
an organic thin film layer formed on an exposed lower electrode and the insulating film;
a luminescent layer formed on a portion of the organic thin film layer corresponding to the lower electrode; and
an upper electrode formed on the substrate,
wherein a portion of the organic thin film layer under the luminescent layer has a surface characteristic different than a surface characteristic of another portion of the organic thin film layer other than the portion under the luminescent layer,
wherein the portion of the organic thin film layer under the luminescent layer is hydrophilic,
wherein the another portion of the organic thin film layer other than the portion under the luminescent layer is hydrophobic, and
3. The organic electroluminescent display according to claim 2, wherein the organic thin film layer is a hole transport layer.
4. The organic electroluminescent display according to claim 3, wherein the hole transport layer is formed of PEDOT (Poly-3,4-Ethylenedioxythiophene) or PANI (polyaniline).
5. The organic electroluminescent display according to claim 2, wherein the another portion of the organic thin film layer other than the portion under the luminescent layer, has an UV ray treated portion and a higher resistance value than the portion under the luminescent layer, and the another portion of the organic thin film layer helps prevent leakage current between the organic thin film layer and the lower electrode.
This application claims priority to and the benefit of Korean Patent Application No. 2002-67975 filed on Nov. 4, 2002, the disclosure of which is hereby incorporated by reference in its entirety.
The present invention relates to an organic electroluminescent display and, more particularly, to an organic polymer electroluminescent device capable of preventing leakage current between adjacent pixels and improving inkjet-printing quality of a luminescent layer by selectively treating the surface of a hole transport layer and a method for fabricating the same.
FIG. 1 illustrates a cross sectional view of one pixel of a conventional organic electroluminescent display.
Referring to FIG. 1, a buffer layer 110 is formed on an insulating substrate 100, and a thin film transistor 120 is formed on the buffer layer 110 in an ordinary manner. As shown in FIG. 1, the thin film transistor comprises a gate 125, a source electrode 127, which is electrically connected to the source region 121, and a drain electrode 129 which is electrically connected to the drain region 123.
A via hole 135 for exposing one of the source electrode 127 or the drain electrode 129, e.g., the drain electrode 129 is formed on an insulating film 130 after the insulating film 130 is formed on the thin film transistor 120 and the buffer layer 110. A lower electrode 140 which is connected to the drain electrode 129, for example, through the via hole 135 is formed on the insulating film 130. An opening part 155 for exposing the lower electrode 140 is formed by patterning a planarization film 150 after the planarization film 150 is deposited on the substrate.
Subsequently, a hole transport layer 160 is formed, for example, by spin coating an organic material such as PEDOT (Poly-3, 4-Ethylenedioxythiophene) or PANI (polyaniline) on the substrate. A luminescent layer 170 is formed on the hole transport layer 160 of the opening part 155 via an inkjet process, and an upper electrode 180 is formed over the substrate.
Ordinarily, the luminescent layer is formed by using an inkjet process or by using laser induced thermal imaging (LITI) process when an organic polymer material is used as the luminescent layer of the organic electroluminescent display.
The inkjet process is a process for forming the luminescent layer on a lower electrode by injecting the solution onto the substrate from the inkjet head. The solution is ejected at a high speed from a head containing solution comprising EL (electro-luminescence) material, e.g., organic polymer EL material, such that the solution is arranged while the inkjet head is spaced apart from the substrate at a certain distance.
Although respective R, G and B luminescent layers should be independently formed per each pixel in an organic luminescent display, there has been a problem in that a solution comprising organic polymer material which is ejected from the head is dispersed onto adjacent pixels in case of the inkjet process.
In order to solve the problem, it is suggested in Korean Patent Application No. 10-1999-7010647 that a luminescent layer is formed after forming a bank layer to cover the edge part of the lower electrode per each pixel. The bank layer is formed of an insulating material. The method for forming a luminescent layer via an inkjet process using the bank layer enables the luminescent layer to be independently formed per each pixel by preventing a solution comprising an organic polymer material from being dispersed onto adjacent other pixels. Thus, by using the bank layer the solution is provided only on the upper part of the lower electrode of a relevant pixel.
However, there has been a problem in that printing quality is lowered as a solution comprising an organic polymer material is dispersed on the bank layer since surface characteristics of the hole transport layer are maintained in all the pixels on the substrate by forming a hole transport layer over the substrate after the bank layer is formed, even when the inkjet process uses the bank layer.
Furthermore, a conventional organic electroluminescent display forms a hole transport layer 160 that has conductivity between the lower electrode 140 and the luminescent layer 170. Thus, luminescence efficiency is improved by improving injection efficiency of holes from the lower electrode 140 to the luminescent layer 170. However, there has been a problem that light is emitted even from adjacent off pixels because the hole transport layer which is conductive is formed over the substrate. Thus, leakage current flows between the hole transport layer 160, which is conductive and the lower electrode 140.
There have also been problems in that a process for forming an additional partition wall is required, and adhesion defects are generated between the succeeding cathode electrode and the organic luminescent layer due to the stepped profile of a the thick partition wall. When the organic luminescent layer is formed using a partition wall for defining a pixel region on which the organic luminescent layer is to be formed, a thick partition wall should be formed to cover the edge part of a pixel electrode.
This invention provides a method of fabricating an organic electroluminescent display by forming a lower electrode on a substrate and forming an insulating film with an opening part for exposing a portion of the lower electrode. An organic thin film is formed on the substrate and a surface of a portion of the organic thin film layer is selectively treated. A luminescent layer is formed on another portion of the organic thin film layer; and an upper electrode is formed on the front of the substrate.
FIG. 1 is a cross sectional view of a conventional organic electroluminescent display.
FIGS. 2A, 2B and 2C are cross sectional views for explaining a method for fabricating an organic electroluminescent display using UV surface treatment according to exemplary embodiments of the present invention.
FIGS. 2A, 2B and 2C illustrate cross sectional structures for explaining a method for fabricating an active matrix organic electroluminescent display according to exemplary embodiments of the present invention.
Referring to FIG. 2A, a buffer layer 210 is formed on an insulating substrate 200, and a thin film transistor 220 is formed on the buffer layer 210. The thin film transistor 220 comprises a source region 212 and a drain region 223 which are formed on an activation layer. The thin film transistor 220 further comprises a gate 225, a source electrode 227 which is electrically connect to the source region 212 and a drain electrode 229, which is electrically connected to the drain region 223.
An insulating film 230 is formed over the buffer layer 210 and the thin film transistor 220. A via hole 235 exposes one of the source electrode 227 or the drain electrode 229, e.g., the drain electrode 229 and is formed by etching the insulating film 230. A lower electrode 240, which is connected to the drain electrode 229 through the via hole 235, is formed on the insulating film 230.
A planarization film 250 is formed by spin coating a planarization material, such as, an insulating layer of acryl on the substrate, and an opening part 255 is formed by etching the planarization film 250 so that a portion of the lower electrode 240 is exposed. A hole transport layer 260 is formed by spin coating a conductive polymer material, such as, PEDOT (Poly-3, 4-Ethylenediozythiphene) or PANI (polyaniline) on the substrate including the opening part 255.
As shown in FIG. 2B, the surface of the hole transport layer 260 is treated by selectively irradiating UV rays 310 onto the hole transport layer 260. The surface of the hole transport layer 260 is selectively treated by irradiating UV rays 310 onto the hole transport layer 260 while a portion of the hole transport layer 260 corresponding to the lower electrode 240, namely, a portion corresponding to a luminescence region of each pixel is masked using a mask 300. An un-masked portion 265 of the hole-transport layer 260 where the surface is treated by irradiation of UV rays, that is, the non-luminescence region of each pixel has hydrophobicity. The masked portion 261 of the hole-transport layer 260 on which UV rays are not irradiated, that is, the luminescence region has hydrophilicity. Therefore, un-masked portion 265 of the hole-transport layer 260 where the surface is treated by irradiation of UV rays has surface characteristics which are different from the masked portion 261 of the hole-transport layer 260 on which UV rays are not irradiated. Also, the un-masked portion 265 of the hole-transport layer 260 has a relatively high resistance value compared with the masked portion 261 of the hole-transport layer 260 so that the un-masked portion 265 where the surface is treated by irradiation of UV rays is in the nonconductive state.
Referring to FIG. 2C, a luminescent layer 270 is formed on the hole transport layer 260 via an inkjet process, wherein a solution containing an organic polymer material is dispersed onto the hole transport layer 260. The solution which is ejected from the inkjet head is prevented from dispersing onto neighboring pixels because the surface of the un-masked portion 265 of the hole-transport layer which corresponds to a non-luminescence region in the hole-transport layer 260 is treated with UV rays. Thus, the un-masked portion 265 of the hole transport layer 260 which corresponds to a non-luminescence region has surface characteristics different from the masked portion 261 of the hole transport layer 260 which corresponds to a luminescence region over the lower electrode 240. Therefore, the luminescent layer 270 does not influence neighboring pixels and is formed over the upper portion of the lower electrode 240 of a relevant pixel. It is possible for the luminescent layer 270 to only be formed on the upper portion of the lower electrode 240 of a relevant pixel.
Furthermore, the masked portion 261 of the hole-transport layer which corresponds to a luminescence region in the hole transport layer 260 maintains the conductive state and is to improve luminescence efficiency by improving the injection efficiency of holes from the lower electrode 240 to the organic luminescent layer 270. The un-masked portion 265 of the hole-transport layer 260 becomes non-conductive by the UV surface treatment so that flow of leakage current between adjacent pixels via the hole transport layer 260 and the lower electrode 240 is prevented.
A method for fabricating an organic electroluminescent display using UV surface treatment of the present invention can not only be applied to active matrix and passive matrix displays as well as front-emission luminescent and rear-emission luminescent displays, but can also be applied to a method for fabricating a flat panel display using inkjet process.
Although exemplary embodiments of the present invention illustrate methods for UV surface treatment by forming a hole transport layer on a planarization film, the various embodiments of the present invention can also be applied to a method for fabricating an organic electroluminescent display by forming the hole transport layer and performing UV surface treatment after forming a bank layer on the planarization film 250.
An organic electroluminescent display and a method for fabricating the same according to the present invention prevent all and/or substantially all leakage current between adjacent pixels by irradiating UV rays and treating the surface of a portion of the hole transport layer other than the luminescent region of each pixel. Thus, printing quality is improved when forming a luminescent layer by an inkjet process and the resistance value of a portion on which UV rays are irradiated is increased.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS5253100 *Jun 27, 1989Oct 12, 1993The Board Of Governors For Higher Education, State Of Rhode Island And Providence PlantationsSolid electrolytes for conducting polymer-based color switchable windows and electronic display servicesUS5705888 *Sep 6, 1995Jan 6, 1998U.S. Philips CorporationElectroluminescent device comprising a transparent structured electrode layer made from a conductive polymerUS5719467 *Jul 27, 1995Feb 17, 1998Hewlett-Packard CompanyOrganic electroluminescent deviceUS5798170 *Feb 29, 1996Aug 25, 1998Uniax CorporationLong operating life for polymer light-emitting diodesUS5856409 *Aug 9, 1993Jan 5, 1999Dow Corning CorporationMethod of making hydrophobic copolymers hydrophilicUS6045977 *Feb 19, 1998Apr 4, 2000Lucent Technologies Inc.Process for patterning conductive polyaniline filmsUS6285124 *Jan 6, 1999Sep 4, 2001Pioneer Electronic CorporationOrganic EL display panel having a conductive high polymer layer between an anode layer and an organic EL layerUS6416885 *Aug 28, 1998Jul 9, 2002Cambridge Display Technology LimitedElectroluminescent deviceUS6649327 *Oct 25, 2001Nov 18, 2003The United States Of America As Represented By The Secretary Of The NavyMethod of patterning electrically conductive polymersUS6689632 *Dec 27, 2002Feb 10, 2004Lg.Philips Lcd Co., Ltd.Organic electroluminescence display device and fabricating method of the sameUS6866946 *Nov 29, 2000Mar 15, 2005Dupont Displays, Inc.High resistance polyaniline useful in high efficiency pixellated polymer electronic displaysUS6933520 *Feb 4, 2003Aug 23, 2005Semiconductor Energy Laboratory Co., Ltd.Light emitting deviceUS20020074936Sep 17, 2001Jun 20, 2002Semiconductor Energy Laboratory Co., Ltd.Display device and method of fabricating the display deviceUS20030227253 *Jan 16, 2003Dec 11, 2003Semiconductor Energy Laboratory Co., Ltd.Display device and method for manufacturing thereofUS20040214039 *Apr 12, 2002Oct 28, 2004Mackenzie J. DevinOpoelectronic devices and a method for producing the sameGB2332895A Title not availableJP2002246172A Title not availableJPH04255692A Title not availableJPH09230129A Title not availableJPH11297472A Title not availableWO1996008047A2Aug 28, 1995Mar 14, 1996Philips Electronics N.V.Electroluminescent device comprising a transparent structured electrode layer made from a conductive polymer* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS7601567 *Dec 12, 2006Oct 13, 2009Samsung Mobile Display Co., Ltd.Method of preparing organic thin film transistor, organic thin film transistor, and organic light-emitting display device including the organic thin film transistorUS8040056 *Apr 24, 2009Oct 18, 2011Toppan Printing Co., Ltd.Organic EL display panel and method for manufacturing thereofUS9419062Feb 10, 2012Aug 16, 2016Samsung Display Co., Ltd.Organic light emitting display devicesUS20070134857 *Dec 12, 2006Jun 14, 2007Suh Min-ChulMethod of preparing organic thin film transistor, organic thin film transistor, and organic light-emitting display device including the organic thin film transistorUS20100078630 *Sep 18, 2009Apr 1, 2010Toppan Printing Co.,Ltd.Organic Electroluminescence Element, Method for Manufacturing the Same, Image Display Unit and Illuminating DeviceUS20100079067 *Apr 24, 2009Apr 1, 2010Toppan Printing Co., LtdOrganic EL Display Panel and Method for Manufacturing Thereof* Cited by examinerClassifications U.S. Classification313/506, 313/503, 428/917, 313/504, 428/690International ClassificationH05B33/10, H05B33/12, H01J1/62, H01L51/56, H01L27/32, H05B33/26, H01L51/30, H05B33/00, H01L51/00, H05B33/22, H01L51/50, H01L51/40Cooperative ClassificationY10S428/917, H05B33/26, H01L51/0005, H01L27/3295, H01L51/0037, H01L51/56, H01L51/5048European ClassificationH01L51/00A2B2B, H05B33/26Legal EventsDateCodeEventDescriptionOct 14, 2003ASAssignmentOwner name: SAMSUNG SDI CO., LTD., KOREA, REPUBLIC OFFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:PARK, JOON YOUNG;KIM, JAE JUNG;REEL/FRAME:014598/0072Effective date: 20031010Jun 4, 2004ASAssignmentOwner name: SAMSUNG SDI CO., LTD., KOREA, REPUBLIC OFFree format text: RE-RECORD TO CORRECT THE ADDRESS OF THE ASSIGNEE, PREVIOUSLY RECORDED ON REEL 014598 FRAME 0072, ASSIGNOR CONFIRMS THE ASSIGNMENT OF THE ENTIRE INTEREST.;ASSIGNORS:PARK, JOON YOUNG;KIM, JAE JUNG;REEL/FRAME:015451/0368Effective date: 20031010Dec 15, 2008ASAssignmentOwner name: SAMSUNG MOBILE DISPLAY CO., LTD., KOREA, REPUBLICFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SAMSUNG SDI CO., LTD.;REEL/FRAME:022024/0026Effective date: 20081212Owner name: SAMSUNG MOBILE DISPLAY CO., LTD.,KOREA, REPUBLIC OFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SAMSUNG SDI CO., LTD.;REEL/FRAME:022024/0026Effective date: 20081212Mar 29, 2011FPAYFee paymentYear of fee payment: 4Aug 29, 2012ASAssignmentOwner name: SAMSUNG DISPLAY CO., LTD., KOREA, REPUBLIC OFFree format text: MERGER;ASSIGNOR:SAMSUNG MOBILE DISPLAY CO., LTD.;REEL/FRAME:028884/0108Effective date: 20120702Apr 10, 2015FPAYFee paymentYear of fee payment: 8RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services