Case 2:20-cv-00234-JRG Document 1-7 Filed 07/13/20 Page 1 of 12 PageID #: 133
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`Exhibit 7
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`Case 2:20-cv-00234-JRG Document 1-7 Filed 07/13/20 Page 2 of 12 PageID #: 134
`
`(12) United States Patent
`Tsai et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,566,805 B1
`May 20, 2003
`
`USOO6566805B1
`
`(54) ORGANIC ELECTRO-LUMINESCENT
`DEVICE WITH FIRST AND SECOND
`COMPOSITE LAYERS
`
`(75) Inventors: Rung-Ywan Tsai, Taoyuan Hsien
`(TW); Ching-Ian Chao, Hsinchu Hsien
`(TW); Chia-Shy Chang, Hsinchu
`(TW); Mu-Yi Hua, Miaoli Hsien (TW)
`(73) Assignee: Industrial Technology Research
`Institute, Hsinchu (TW)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 253 days.
`
`(*) Notice:
`
`(21) Appl. No.: 09/672,920
`(22) Filed:
`Sep. 28, 2000
`(30)
`Foreign Application Priority Data
`Jun. 1, 2000 (TW) ....................................... 89110673 A
`(51) Int. Cl." ............................. H01J 1/62; H01J 63/04
`(52) U.S. Cl. ....................... 313/504; 313/506; 313/509;
`428/690
`(58) Field of Search ................................. 313/504, 503,
`313/506, 509; 428/690
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4.885.211 A 12/1989 Tang et al. ................. 428/457
`5,237,439 A 8/1993 Misono et al. .............. 349/122
`5,245.457 A 9/1993 Fukuchi ...................... 349/138
`5,808,715 A 9/1998 Tsai et al. ..
`... 349/122
`5,844,363 A 12/1998 Gu et al. ......
`... 313/506
`5,909,081. A * 6/1999 Eida et al. ...........
`... 313/504
`6.228,514 B1 * 5/2001 Tadashi et al. ......
`... 313/504
`6,235,414 B1 * 5/2001 Epstein et al. .......
`... 257/103
`
`
`
`OTHER PUBLICATIONS
`“The “Plastic” Led: A Flexible Lihgt-Emitting Device
`Using a Polyaniline Transparent Electrode”, Synthetic Met
`als, 55-57 (1993), pp4123–27.
`“Annealing effects on the properties of indium tin oxide
`films coated on Soda glasses with a barrier layer of
`TiO2-SiO2 composite films”, Opt. Eng. 36(8), p2335-40
`(Aug. 1997).
`“Influences of the deposition rate on the microstructure and
`hardness of composite films prepared by reactive ion-as
`sisted coevaporation”, Opt. Eng. 34(10) p3075-82 (Oct.
`1995).
`* cited by examiner
`Primary Examiner Vip Patel
`ASSistant Examiner Kevin Quarterman
`(74) Attorney, Agent, or Firm J. C. Patents
`(57)
`ABSTRACT
`A flexible organic electro-luminescent device is provided, in
`which a titanium dioxide-Silicon dioxide composite layer is
`formed on the upper and lower Surfaces of a transparent
`plastic Substrate. A transparent conductive electrode and an
`organic luminescent layer are formed in Sequence on one of
`Surfaces of the composite layer. The organic luminescent
`layer is either Small molecule luminescent material or poly
`mer luminescent material. Then, a metal electrode is formed
`on the organic luminescent layer, and a Silicon dioxide
`protecting layer is formed on the metal electrode to enclose
`the metal electrode and the organic luminescent layer com
`pletely. The titanium dioxide-silicon dioxide composite
`layer and Silicon dioxide protecting layer are formed by
`ion-assisted electron gun evaporation in the temperature
`lower than 100° C., which does not result in the thermal
`loading to the Small molecule and polymer organic electro
`luminescent device.
`
`18 Claims, 4 Drawing Sheets
`
`212
`
`208
`206
`204O
`202O
`2OO
`
`202b
`204b
`
`

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`Case 2:20-cv-00234-JRG Document 1-7 Filed 07/13/20 Page 3 of 12 PageID #: 135
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`U.S. Patent
`
`May 20, 2003
`
`Sheet 1 of 4
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`US 6,566,805 B1
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`+
`
`106
`1 O4
`102
`
`-
`
`FIG. 1 (PRIOR ART)
`
`

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`U.S. Patent
`
`May 20, 2003
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`Sheet 2 of 4
`
`US 6,566,805 B1
`
`202O
`
`200
`
`FIG. 2A
`
`202b
`
`204O
`He - 202a
`
`FIG. 2B
`
`a
`
`202b
`204b
`
`2O6
`
`2040
`- - 202a
`
`
`
`6
`
`202b
`204b.
`
`204d
`202O
`200
`202b
`204b.
`
`

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`U.S. Patent
`
`May 20, 2003
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`Sheet 3 of 4
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`US 6,566,805 B1
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`
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`

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`Case 2:20-cv-00234-JRG Document 1-7 Filed 07/13/20 Page 6 of 12 PageID #: 138
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`U.S. Patent
`
`May 20, 2003
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`Sheet 4 of 4
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`US 6,566,805 B1
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`
`
`s
`
`eduous uDu
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`Case 2:20-cv-00234-JRG Document 1-7 Filed 07/13/20 Page 7 of 12 PageID #: 139
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`US 6,566,805 B1
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`1
`ORGANIC ELECTRO-LUMNESCENT
`DEVICE WITH FIRST AND SECOND
`COMPOSITE LAYERS
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`This application claims the priority benefit of Taiwan
`application serial no. 89110673, filed Jun. 1, 2000.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of Invention
`The present invention relates to an organic electro
`luminescent device (OEL) and, especially to a flexible
`organic electro-luminescent device and the process thereof.
`2. Description of Related Art
`The organic electro-luminescent material has character
`istics Such as Self-emitting, broad range of Visual angle
`(0–160), high response speed, low driving voltage, and full
`colors. It has been put into practice as a color plane display
`panel, Such as a compact display panel, an out-door display
`billboard, a computer, and a television monitor. The organic
`electro-luminescent material has been developed since 1960.
`The organic electro-luminescent material usually is used to
`form a light emitting layer (EML). The light emitting layer
`incorporates between a metal electrode and a transparent
`anode, Such that an organic electro-luminescent display is
`formed.
`The organic electro-luminescent devices are divided into
`two groups according to the type of material used: one is a
`Small molecule organic electro-luminescent device and a
`polymer organic electro-luminescent device. In the early
`1980s, U.S. A. Eastman Kodak utilized tri-(8-
`hydroxyquinoline) aluminium (Ald) to form an organic
`emitting layer and inserts a hole injecting layer between the
`emitting layer and the anode. This manner greatly improves
`the characteristics and Stability of the organic electro
`luminescent device, and launches the application of the
`organic electro-luminescent device. In 1990, Cambridge
`University of England utilized poly p-phenylene Vinylene
`(PPV) conjugated polymer to fabricate a polymer organic
`electro-luminescent device. Since the materials of ploy(p-
`phenylene vinylene (PPV) type have the characteristics
`Similar to Semiconductors and the easy fabrication proceSS
`for the polymer organic electro-luminescent devices, it
`highly interests people to make intensive researches again.
`Since plastic has properties of transparency, light weight,
`flexibility, proper Stretching Strength and brittle resistance,
`plastic can be used as a Substrate for a liquid crystal display
`(LCD) that is portable, thin and light. For example, the
`plastic Substrate disclosed in U.S. Pat. Nos. 5.237,439 and
`5.245,457 by Sharp Co. Ltd., Japan. The plastic substrate
`can also be used as Substrates for the organic electro
`luminescent devices (for example, U.S. Pat. No. 5,844,363
`assigned to Princeton University, USA). The plastic Sub
`Strates can be also applied in other optical display devices.
`The material used for the plastic Substrate is usually
`acrylic resin, epoxy resin, polyethylene terephthalate (PET),
`or polycarbonate (PC). However, the above materials used
`for the plastic Substrate can not endure high temperature.
`Therefore, in Such processes for producing liquid crystal
`displays and organic electro-luminescent devices, the tem
`perature can not exceed 200 C. when a transparent con
`ductive electrode of indium tin oxide (ITO) is formed on the
`plastic Substrate. A Surface treatment of hard coating is also
`
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`necessary to be performed to prevent the plastic Substrate
`from being Scraped, Since the plastic material usually is Soft.
`Further, the plastic Substrate can not effectively prevent
`water and oxygen from entering because of its low packing
`density, which also causes the absorption of water and
`oxygen. However, the organic film formed in the organic
`electro-luminescent device is very Sensitive to the water and
`oxygen, So that the organic film would be damaged by the
`water and oxygen, which results in a decrease in the lifetime
`of the organic electro-luminescent device. Moreover, the
`water and oxygen contained in the plastic material are often
`released during vacuum deposition, causing that the evapo
`rated layer has poor adhesion. Also, the water and oxygen
`are gradually released after the device is accomplished,
`resulting in deterioration of performance for the conductive
`electrode and luminescent material of the organic electro
`luminescent device. The foregoing factors may cause poor
`performance and low Stability of the plastic organic electro
`luminescent device.
`Referring to FIG. 1, a schematic view of the structure of
`the plastic organic electro-luminescent device in the art is
`shown. Such structure is disclosed in U.S. Pat. No. 4,885,
`211. The Structure is fabricated by coating a transparent
`conductive electrode 102 on a Substrate 100, where the
`transparent conductive electrode 102 Serves as a hole injec
`tion layer. The conductive electrode 102 is formed of indium
`tin oxide, with the thickness of 30 nm to 400 nm and an area
`resistance of smaller than 100 S2/cm. Further, an organic
`emitting layer 104 is coated on the transparent electrode 102.
`Then, a metal conductive electrode 106 having a low work
`function, Serving as an electron injection layer (EIL) is
`coated on the surface of the organic emitting layer 104. The
`material used for the metal conductive electrode 106 com
`prises Li, Mg, Ca, Al, Ag, In, or alloys thereof. The metal
`conductive electrode 106 has a thickness of 100 nm to 400
`.
`The organic electro-luminescent devices are generally
`divided into two types of a Small molecule organic electro
`luminescent device and a polymer organic electro
`luminescent device according to the organic material used in
`the organic electro-luminescent device. The methods for
`coating the emitting layer of the organic electro-luminescent
`device can also be different.
`The Small molecule organic electro-luminescent layer
`usually has a two-layer Structure, as described in U.S. Pat.
`No. 5,844,363 proposed by Princeton University, USA. A
`hole transport layer (HTL) having the thickness such as 80
`nm and an emitting layer having the thickness of Such as 80
`nm are formed in Sequence on the indium tin oxide layer by
`Vacuum deposition. The material used for the hole transport
`layer comprises N,N'-dipheny-N,N'-(m-tolyl)benzidine
`(TPD). The material used for the emitting layer comprises
`tri-(8-hydroxyquinoline)aluminum (Alq).
`The polymer organic electro-luminescent layer usually
`has a single-layer Structure, as described in the Synthetic
`Metals, 55–57, 4123-4127 (1993) published by G. Gustafs
`Son et al. In Such structure, a poly(2-methoxy-5-(2-ethyl
`hexyloxy)p-phenylene-vinylene (MEH-PPV) having a
`thickness of 50 nm to 100 nm is used as the emitting layer.
`In the polymer organic electro-luminescent device, the
`transparent conductive electrode is an indium tin oxide layer
`or a polyaniline (PANI) layer with camphor sulfonic acid
`(CSA) formed by Spin coating, dipping, spray coating,
`doctor knife, Screen printing, or inkjet printing.
`However, either in the Small molecule organic electro
`luminescent device or the polymer organic electro
`
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`4
`oxygen barrier layer; (4) Serving as a bonding layer between
`the plastic Substrate and indium tin oxide layer to prevent
`cracks of the layers caused by the difference in thermal
`expansion between indium tin oxide layer and the plastic
`Substrate or by bending.
`SUMMARY OF THE INVENTION
`The present invention provides an organic electro
`luminescent device and the process to fabricate the same.
`According to the present invention, a topcoat and undercoat
`are formed on the transparent conductive electrodes of the
`Small molecule and/or polymer organic electro-luminescent
`device, respectively. The topcoat and the undercoat Serve as
`the water and oxygen barrier layer and hard protecting layer
`for the transparent electrodes of the organic electo
`luminescent device. The topcoat and the undercoat also
`Serve as the protecting layer for the metal conductive
`electrode (i.e. electron injection layer) in the organic electro
`luminescent device. The topcoat, undercoat and transparent
`conductive layer are designed to have the appropriate thick
`neSS ranges, So as to increase the luminescent efficiency of
`the organic electro-luminescent device.
`According to the above and other objects of the present
`invention, a proceSS for fabricating is provided, in which a
`transparent plastic Substrate having a first Surface and a
`Second Surface is provided. A first composite layer and a
`Second composite layer are formed on the first and Second
`Surfaces of the transparent plastic Substrate by low
`temperature ion-assisted electron gun evaporation. A trans
`parent electrode is formed on the first composite layer by
`low-temperature ion-assisted electron gun evaporation. An
`organic emitting layer of Small molecule luminescent mate
`rial is formed on the transparent electrode by thermal
`evaporation, or an organic emitting layer of polymer lumi
`neScent material is formed on the transparent electrode by
`Spin coating. A metal electrode is formed on the organic
`emitting layer by thermal evaporation. Also and, a protecting
`layer is formed on the metal electrode by low-temperature
`ion-assisted electron gun evaporation to enclose the metal
`electrode and the organic emitting layer completely.
`Further, according to the above and other objects, an
`organic electro-luminescent device is provided. The organic
`electro-luminescent device comprises a plastic Substrate
`having a first Surface and a Second Surface. A first composite
`layer and a Second composite layer are formed on the first
`Surface and the Second Surface of the plastic Substrate,
`respectively. An indium tin oxide electrode is formed on the
`first composite layer. The first composite layer is located
`between the plastic Substrate and the indium tin oxide
`electrode. An organic emitting layer of Small molecule or
`polymer luminescent material is formed on the indium tin
`oxide electrode. A metal electrode is formed on the organic
`emitting layer So as to allow the organic emitting layer to be
`between the indium tin oxide electrode and the metal
`electrode. Additionally, a Silicon dioxide protecting layer
`can be also applied on the metal electrode to enclose the
`metal electrode and the organic emitting layer completely.
`BRIEF DESCRIPTION OF THE DRAWINGS
`The accompanying drawings are included to provide a
`further understanding of the invention, and are incorporated
`in and constitute a part of this Specification. The drawings
`illustrate embodiments of the invention and, together with
`the description, Serve to explain the principle of the inven
`tion. In the drawings,
`FIG. 1 is the schematic view of the structure of the plastic
`organic electro-luminescent device in the art,
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`luminescent device, the organic electro-luminescent layer
`(for example, 104 in FIG. 1) and metal electrode (for
`example, 106 in FIG. 1) in these devices are very sensitive
`to water and oxygen. This results in a reaction with water
`and oxygen, Such that these devices are damaged in the
`atmosphere that contains even a little amount of water and
`oxygen. Therefore, in the process for producing the organic
`electro-luminescent device, the demand for controlling the
`content of the water and oxygen in the atmosphere is strict,
`i.e. the required content of the water and oxygen therein is
`no more than 1 ppm. Further, U.S. Pat. No. 5,844,363
`discloses a flexible Small molecule organic electro
`luminescent device formed by vacuum deposition, but it still
`failed to provide a solution to effectively prevent the water
`and oxygen from being released from the plastic Substrate.
`Also, in the research published by G. Gustafsson et al., the
`flexible polymer organic electro-luminescent device is
`formed by Spin coating, without any treatment for the plastic
`Substrate.
`For the plastic thin film liquid crystal display, the water
`and oxygen released or penetrated from the plastic Substrate
`are necessarily to be avoided, So as to protect the plastic
`Substrate. Also, the thermal StreSS between the plastic Sub
`Strate and the indium tin oxide electrode is necessary to be
`reduced to prevent the layers from being cracked. Therefore,
`a protecting film layer must be coated between the indium
`tin oxide layer and the plastic Substrate.
`In U.S. Pat. No. 5,237,439, a hard coating layer having the
`thickness of 2 um to 6 um is formed by dipping and baking
`on both Surfaces of the plastic Substrate which has a thick
`ness of 0.1 mm to 0.5 mm. The material used for forming the
`hard coating layer comprises organosilane, acrylic acid,
`melamine, and urethane, all of which are doped with boron.
`Such a hard coating layer can protect the plastic Substrate
`and absorb the water released from the plastic substrate. The
`hard coating layer can also buffer thermal StreSS existing
`between the undercoat of SiOX with 10 nm to 60 nm in
`thickness, and the indium tin oxide electrode, So that cracks
`in the indium tin oxide layer can be avoided. Moreover, a
`TiOx buffer layer can also be formed between the organic
`hard coating layer without boron doping and the undercoat
`of SiOx to achieve the same properties with that of the
`boron-doped organic hard layer. The above TiOx buffer
`layer, SiOx undercoat and ITO electrode all are formed by
`Sputtering deposition.
`In U.S. Pat. No. 5,245,457, a method of forming topcoat
`in low temperature is provided. In Such method, the com
`mercially available Silica-containing oil for coating is
`applied over the Surface of the indium tin oxide electrode on
`the plastic Substrate. After exposure to the radiation of UV
`50
`light, a low temperature treatment is carried out in the
`temperature lower than 200 C. to form a topcoat and
`prevent the plastic Substrate from being damaged.
`In U.S. Pat. No. 5,808,715, a titanium dioxide-silicon
`dioxide composite layer is provided to Serve as the topcoat
`and undercoat of the liquid crystal display device, in which
`the titanium dioxide-Silicon dioxide composite layer is
`formed as the topcoat and undercoat for the transparent
`electrode of the plastic thin film liquid crystal display by
`ion-assisted electron gun evaporation under a temperature
`lower than 100° C. Such a titanium dioxide-silicon dioxide
`composite layer has Superior insulating property, consider
`able hardness, and Smooth Surfaces. It has the following
`advantages: (1) preventing shortage between electrodes
`caused by conductive impurities having the same size as or
`larger than the gap between electrodes; (2) protecting plastic
`Substrate from being Scraped; (3) Serving as a water and
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`tronic gun evaporation, the Starting material for evaporation
`is Ti-O tablets and Silicon dioxide particles. To control the
`composition of the titanium dioxide-Silicon dioxide com
`posite layer, the evaporation rate of titanium dioxide is set to
`be about 0.2 mm/s, and that of silicon dioxide is varied from
`0 nm/s to about 2 mm/s. The gas used for reaction is a
`mixture of argon with high purity of, for example, more than
`99.99% and oxygen (O) with high purity of, for example,
`more than 99.99%. The flow rate of the argon is about 18
`ml/min (about 18 sccm). The flow rate of the oxygen is about
`30 ml/min (about 30 sccm). The discharge voltage of the ion
`gun Source is about 100 volts with a discharge current of
`about 40 A. Thus, the total energy of the ion source is about
`90 eV. The evaporation process of the titanium dioxide
`Silicon dioxide composite layer is entailed with reference to
`the literature published for example by the present inventors
`(Opt. Eng 34, 3075-3982 (1995) and Opt. Eng. 36,
`2335-2340 (1997)).
`Referring to FIG. 2C, a transparent conductive electrode
`206 is formed on the surface of the first composite layer
`204a. The transparent conductive plastic electrode for the
`organic electro-luminescent device is then formed. The
`method for forming the transparent conductive layer 206
`includes ion-assisted electronic gun evaporation in the same
`vacuum chamber in a substrate temperature of less than 100
`C. The Starting material for evaporating the transparent
`conductive layer 206 is indium tin oxide in the form of
`tablets, for example, in which the ratio of tin oxide (SnO)
`is 10% in weight (i.e. 90%. In O-10%SnO). The transpar
`ent conductive electrode includes indium tin oxide has the
`thickness of 30 nm to 400 nm and an area resistance of less
`than 100 S2/cm°. If a display is needed for the conductive
`plastic Substrate, the electrode pattern required for forming
`the display can be formed on the transparent conductive
`layer, i.e. the transparent conductive electrode 206 having
`the defined pattern is formed.
`Referring to FIG. 2D, after the transparent conductive
`electrode 206 for the organic electro-luminescent device is
`completed, an electro-emitting layer (EML) 208 is formed
`on the transparent conductive electrode 206. The EML 208
`is formed of Such as Single-layered luminescent material or
`multi-layered luminescent material. The EML 208 includes
`Small molecule luminescent material and polymer lumines
`cent material. If the material used for the EML 208 is Small
`molecule, one or more layers of the Small molecule lumi
`neScent material can be evaporated on the transparent con
`ductive electrode 206 by thermal evaporation. If the EML
`208 is formed of polymer luminescent material, one or more
`layers of the polymer luminescent material can be deposited
`on the transparent conductive electrode 206 by Spin coating.
`Referring to FIG. 2E, a metal conductive electrode 210 is
`formed on the EML 208 of the plastic substrate 200, serving
`as an electron injection layer (EIL). The method of forming
`the metal conductive electrode 210 includes thermal evapo
`ration. The conductive electrode 210 is formed of Such as
`Single-layered metal material, or multi-layered metal mate
`rial. The metal conductive electrode 210 includes lithium,
`magnesium, calcium, aluminum, Silver, indium or the alloy
`thereof, having a thickness of about 100 nm to about 400
`.
`Referring to FIG. 2F, after the metal conductive electrode
`210 is formed, a protecting layer 212 is formed on the metal
`conductive electrode 210, where the plastic Substrate 200
`currently has the first composite layer 204a, the transparent
`conductive electrode 206, the emitting layer 208, and the
`metal conductive electrode 210. The organic luminescent
`material and the metal electrode are also enclosed by the
`
`S
`FIGS. 2A to 2F are the cross sectional view of the organic
`electro-luminescent device and the process thereof accord
`ing to one of the preferred embodiments of the present
`invention; and
`FIG. 3 is the experimental result of the near IR transmit
`tance spectra for the polycarbonate plastic Substrate with and
`without titanium dioxide-Silicon dioxide composite layer as
`a function of TiO2 content, which is obtained at relative
`humidity of 95% and room temperature for 4 hrs.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`Referring to FIGS. 2A to 2F, a method of fabricating an
`organic electro-luminescent device according to one of the
`preferable examples of the present invention is Schemati
`cally illustrated. Such organic electro-luminescent device
`can include flexible organic electro-luminescent devices. AS
`shown in FIG. 2A, a transparent substrate 200 for visible
`light having a first surface 202a and a second surface 202b
`is provided. The plastic Substrate 200 used in the flexible
`plastic organic electro-luminescent device according to the
`present invention comprises polycarbonate (PC), acrylic
`polymethyl methacrylate (Acrylic-PMMA), polyester
`resin, epoxy resin, or the like. The dimension thereof
`(lengthxwidthxthickness) is, for example, 2.5x2.5x0.1
`(mm) or 2.5x2.5x0.25 (mm), with thickness Smaller than or
`about equal to 0.25 mm.
`Referring to FIG. 2B, a composite layer 204a and a
`second composite layer 204b are formed on the first surface
`202a and the second surface 202b of the transparent plastic
`substrate 200, respectively. The method of forming the first
`composite layer 204a and the second composite layer 204b
`includes ion-assisted electron gun evaporation. It is pre
`ferred that transparent plastic substrate 200 is put into the
`vacuum chamber (not shown in drawings) at the temperature
`lower than 100° C. to form an evaporated layer by ion
`assisted electron gun evaporation. The first composite layer
`204a and the second composite layer 204b include, for
`example, a titanium dioxide-silicon dioxide (TiO-SiO2)
`composite layer.
`As shown in FIG. 2B, the first composite layer 204a
`located on the first Surface 202a of the transparent plastic
`substrate 200, with the titanium dioxide (TiO) content in a
`wide range of from 0% to 100% in atomic percentage. This
`means that the ratio of titanium dioxide to Silicon dioxide in
`the first TiO-SiO composite layer can be varied as
`intended. The first composite film 204a has the thickness of
`about 20 nm to about 150 nm. The first composite layer 204a
`not only Serves to Stop the water and oxygen released from
`the inside of the plastic Substrate 200, but also to be used as
`a bonding layer for the indium tin oxide layer 206 and the
`plastic substrate 200.
`In FIG. 2B, the second composite layer 204b located on
`the second surface 202b of the transparent plastic substrate
`200 is similar to the first composite layer 204a. The content
`of titanium dioxide also ranges from 0% to 100%, i.e., the
`ratio of titanium dioxide to Silicon dioxide in the titanium
`dioxide-Silicon dioxide composite layer of the Second com
`posite layer 204b can be varied without restriction. The
`60
`second composite layer 204b has the thickness of about 20
`nm to 150 nm. It serves as a hard layer for protecting the
`transparent plastic Substrate 200 from being Scraped by an
`external force.
`When the first composite layer 204a and the second
`composite layer 204b made with titanium dioxide-silicon
`dioxide composite layers are formed by ion-assisted elec
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`Case 2:20-cv-00234-JRG Document 1-7 Filed 07/13/20 Page 10 of 12 PageID #: 142
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`US 6,566,805 B1
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`7
`protecting layer 212, So as to prevent the water and oxygen
`from reacting with the metal electrode or the organic emit
`ting layer. The life time of the product is thereby effectively
`prolonged. The method of forming the protecting layer 212
`includes ion-assisted electron gun evaporation. It is prefer
`able to put the transparent plastic substrate 200 into the
`vacuum chamber (not shown in drawings) under the condi
`tion that the substrate temperature is less than 100° C. and
`no oxygen gas is added. The protecting layer 212 is evapo
`rated by ion-assisted electron gun evaporation. The protect
`ing layer 212 includes Silicon dioxide (SiO2) having a
`thickness of about 20 nm to about 150 nm.
`The ion-assisted electron gun evaporation of a pure Sili
`con dioxide protecting layer is carried out under the condi
`tion that the Substrate temperature of less than 100° C. and
`no oxygen gas is added. The evaporation rate of the Silicon
`dioxide is kept at about 2 mm/s. The gas used for reaction is
`argon with high purity (more than 99.99%) whose flow rate
`is 18 ml/min. The other ion-assisted evaporating conditions
`thereof are the same with that for the titanium dioxide
`Silicon dioxide composite layer.
`In the flexible plastic organic eletro-luminescent device
`according to the present invention, the first and the Second
`composite layer (204a, 204b), the transparent conductive
`electrode 206, and the protecting layer 212 all can be
`evaporated without heating by the ion-assisted electron gun
`evaporation. Since the Striking of the ions will not result in
`the Significant increase in the temperature of the Substrate,
`the temperature during the proceSS mainly comes from
`evaporation Source. From the results of the experiment, in
`the evaporation process of the present invention, the result
`ant temperature increased by less than 60° C., which does
`not adversely affect the plastic substrate, such as PC or
`PMMA. The process according to the present invention can
`also be suitable for other plastic substrates sensible to
`temperature, Such as polyethylene terephthalate.
`The titanium dioxide-Silicon dioxide composite layer
`obtained by low-temperature ion-assisted electron gun
`evaporation shows an amorphous structure from the analysis
`obtained by X-ray diffraction and transmission electron
`microScope. Since the composite layer will not result in the
`effect of Such as grain boundary Scattering, the luminescent
`efficiency of the organic electro-luminescent device will not
`be reduced.
`Further, the titanium dioxide-Silicon dioxide composite
`layer has very high hardness, 2500 N/mm in average. When
`the content of the titanium dioxide in the titanium dioxide
`Silicon dioxide composite layer is up to 75%, the hardneSS
`thereof is even higher than 4000 N/mm, which is greater
`than the hardness of glass. The plastic Substrates Such as PC
`and PMMA have hardness in the range from only tens to
`hundreds N/mm. Therefore, the plastic substrate can be
`protected effectively by the titanium dioxide-silicon dioxide
`composite layer as a hard protecting layer for the plastic
`Substrate and the metal conductive electrode. It can also
`prevent the organic luminescent device from being damaged
`caused by external force.
`Further, the refraction index of the titanium dioxide
`Silicon dioxide composite layer can be changed by adjusting
`the ratio of the composition. For incident light having a
`wavelength of 550 nm, the refractive index of the composite
`layer is in the range from 1.46 for pure Silicon dioxide to
`2.36 for pure titanium dioxide. Therefore, the combination
`of the titanium dioxide-Silicon dioxide composite layer
`having appropriate composition and thickneSS and the
`indium tin oxide layer having an appropriate optical thick
`
`8
`neSS can result in a significant increase in the luminescent
`efficiency of the organic electro-luminescent device. It can
`be thus used as a transmittance enhanced layer.
`AS characteristics of the titanium dioxide-Silicon dioxide
`composite layer, the water and oxygen are prevented from
`entering into the plastic Substrate from the atmosphere or are
`prevented from being released from the inside of the plastic
`Substrate. See Table 1 and 2, the data shown are the changes
`in weight of the evaporated composite layer of PC and
`PMMA plastic Substrates, with 200 nm in thickness, before
`and after the test which is carried out at a relative humidity
`of 95% and a constant temperature of 25 C. for 6 hours, in
`which the Samples are weighed using a micro Scales. In these
`Tables, the results are also compared with that of blank
`plastic Substrate having no protecting layer.
`Table 1 The weight change of PC plastic Substrate, coated or
`without coated a composite film with a thickness of 200
`nm before and after the humidity test. The test is carried
`out at a relative humidity of 95% and a constant tempera
`ture of 25 C. for 6 hours.
`
`15
`
`Composition
`(at. 76)
`
`TiO,
`100%
`
`TiO,
`75%
`
`TiO,
`50%
`
`TiO,
`25%
`
`SiO,
`100%
`
`X
`
`25
`
`Weight change
`(mg)
`
`O.33
`
`O.16
`
`O.19
`
`O.12
`
`O16
`
`O.21
`
`Table 2 The weight change of PMMA plastic Substrate,
`coated or without coated a composite film with a thick
`ness of 200 nm before and after the humidity test. The test
`is carried out at a relative humidity of 95% and a constant
`temperature of 25 C. for 6 hours.
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Composition (at. 76)
`
`Weight change (mg)
`
`X
`
`2.32
`
`TiO,
`100%
`
`1.76
`
`TiO,
`75%
`
`1.47
`
`As shown in Tables 1 and 2, the prevention of water
`absorption of the PC and PMMA plastic Substrates with an
`evaporated composite layer of 200 nm in thickness is
`improved, as shown in a comparison with the blank plastic
`Substrate having no evaporated layer thereon. Therefore, the
`water and oxygen can be effectively isolated by the titanium
`dioxide-Silicon dioxide composite la