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  Organic multicolor emission and display device and method for manufacturing sameUSPTO Application #: 20080081389Title: Organic multicolor emission and display device and method for manufacturing same Abstract: A transparent first substrate and a second substrate of an organic multicolor emission and display device are positioned opposite to each other with a predetermined clearance and sealed with a gap material that performs desiccating a surrounding atmosphere. The gap material advantageously has different void fractions between in an inner portion facing a sealed space within the device and in an outer portion facing an external atmosphere. Featuring the above structure, an organic multicolor emission and display device of color conversion system has been provided that maintains stable light emitting performance for a long period and exhibits excellent visibility angle characteristic. (end of abstract) Agent: Rossi, Kimms & Mcdowell LLP. - Ashburn, VA, US Inventor: Noriyuki MATSUKAZE USPTO Applicaton #: 20080081389 - Class: 438029000 (USPTO) Related Patent Categories: Semiconductor Device Manufacturing: Process, Making Device Or Circuit Emissive Of Nonelectrical Signal, Including Integrally Formed Optical Element (e.g., Reflective Layer, Luminescent Material, Contoured Surface, Etc.) The Patent Description & Claims data below is from USPTO Patent Application 20080081389. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This is a divisional of application Ser. No. 10/520,951 filed on Jan. 11, 2005, which is a National Phase application of International Application PCT/JP2003/008844 having an international filing date of Jul. 11, 2003, and claims priority to Japanese Application No. JP 2002-206226, filed on Jul. 15, 2002. The disclosure of the PCT and priority applications, in their entirety, including the drawings, claims, and the specification thereof, are incorporated herein by reference. TECHNICAL FIELD OF THE INVENTION [0002] The present invention relates to an organic multicolor emission and display device that allows high precision multicolor display and is excellent in productivity and resistance to environment. More in detail, the invention relates to an organic multicolor emission and display device suited for use in display in image sensors, personal computers, word processors, TV sets, facsimile machines, audio systems, video recorders, car navigation systems, electronic calculators, telephones, portable terminals, and industrial instruments. The invention relates to an organic multicolor emission and display device employing a color conversion system, in particular. The invention also relates to a method of manufacturing such a device. BACKGROUND OF THE INVENTION [0003] With diversification of information in recent years, display devices in information field including solid state imaging devices need "beauty, light weight, thinness, and excellence". In addition, active developments are progressing for low power consumption and fast response. Researches and developments in high precision full color display devices, in particular, are being made widely. [0004] As is well known, in the field of organic electroluminescence (hereinafter also called as organic EL), C. W. Tang et al reported (in Appl. Phys. Lett. 51, 913 (1987)) that high luminance of more than 1,000 cd/m.sup.2 was obtained at an applied voltage of 10 V in a device having a layered structure of thin films of organic molecules. Since the report, researches have been promoted directing to practical application of organic EL devices. Similar devices using organic polymer materials are being actively developed as well. [0005] Organic EL devices are superior to liquid crystal display devices in dependence on angle of visibility and response speed. Further, high luminance and high emission efficiency can be expected owing to high current density at low voltage in comparison with inorganic EL devices and LEDs. [0006] Distinctive features of a display device of organic EL are: (i) high luminance and high contrast, (ii) low voltage drive and high emission efficiency, (iii) high resolution, (iv) wide angle of visibility, (v) fast response, (vi) possibility of microstructure and color display, and (vii) light weight and thinness. Because of these features, organic EL devices are expected to apply to flat panel display to perform "beauty, light weight, thinness, and excellence". [0007] Pioneer Corporation already commercialized green color monochromatic organic EL display for vehicle mounting in November 1997. To meet diversifying social needs, practical implementation of organic EL multicolor display devices is eagerly expected that exhibit long-term stability, fast response, multicolor display, and capability of high precision full-color display. [0008] Multicolor or full-color display of an organic EL color display device can be performed by a method in which emission elements for three primary colors, red, green, and blue, are separately arranged in a matrix form and each element emits light. (Refer to Japanese Unexamined Patent Application Publication Nos. S57-157487, S58-147989, and H3-214593.) To obtain multicolor by using organic light emitting elements, three types of light emitting materials for R, G, and B must be arranged in a matrix form with high precision. Therefore, the method involves technical difficulty and does not allow production with low cost. Further, difference in lifetimes of three light emission materials reveals a drawback that the chromaticity shifts with time. [0009] Another method is known in which a backlight emitting white light and color filters are used and three primary color light transmits the filters. (Refer to Japanese Unexamined Patent Application Publication Nos. H1-315988, H2-273496, and H3-194895.) However, an organic light emitting element has not been found that emits bright white light required to obtain bright RGB and that exhibits long life. [0010] Still another method is also known in which light from a light emitting element is absorbed in fluorescent elements separately arranged in a plane and each fluorescent element emits fluorescent light in each different color. (Refer to Japanese Unexamined Patent Application Publication No. H3-152897.) The method disclosed in this reference, in which a light emitting element is used to obtain multiple colors through fluorescent elements, is applied to CRT and plasma display. [0011] In recent years, a color conversion system has been disclosed in which filters of fluorescent material are used that absorb light from an organic light emitting element and emit fluorescent light in a visible light range. (Refer to Japanese Unexamined Patent Application Publication Nos. H3-152897 and H5-258860.) The light to be emitted from the organic light emitting element is not limited to white light in this system. Therefore, brighter organic light emitting element can be used for a light source. A color conversion system using an organic light emitting element that emits blue light converts the emitted blue light to green light and red light through fluorescent materials by wave length conversion. (Refer to Japanese Unexamined Patent Application Publication Nos. H3-152897, H8-286033, and H9-208944.) By patterning a fluorescent light conversion film containing fluorescent dyes with high precision, a full-color light emitting type display can be constructed using relatively low energy radiation such as near ultraviolet or visible light from the light emitting element. [0012] Methods for pattering a color conversion filter are disclosed as follows. [0013] (a) As in the case of an inorganic fluorescent element, fluorescent dye is dispersed in liquid of resist (photo-reactive polymer). After forming a film by spin-coating or another method, pattering is conducted by photolithography. (Refer to Japanese Unexamined Patent Application Publication Nos. H5-198921 and H5-258860.) (b) Fluorescent dye or pigment is dispersed in basic binder. A film of the above material is patterned by etching in an acidic aqueous solution. (Refer to Japanese Unexamined Patent Application Publication No. H9-208944.) [0014] The color conversion system that is regarded promising for obtaining a multicolor display device, however, has a problem that the fluorescent filter for converting to a fluorescent light with the target wavelength is extremely weak against light with a special wavelength, moisture, heat, and organic solvent. These factors readily decompose the material of the fluorescent filter and causes loss of functions of the filter. Consequently, constraints are posed on the manufacturing process of multicolor organic EL devices. [0015] In a conventional process of manufacturing a multicolor organic EL device of the color conversion system, the process (film deposition, photolithography) of forming a transparent ITO electrode, which is an anode of an organic light emitting element, is liable to deteriorate the conversion characteristics (conversion efficiency, color purity) of the color conversion filter by heat generated in the process. Therefore, it is difficult to form an organic light emitting element directly on a protective layer. [0016] To solve this problem, a so-called inversion structure has been proposed. In the structure, first cathode films are deposited on a transparent substrate. Then, an organic layer, anodes, a protective layer, and color conversion filters are sequentially formed. The structure, however, involves a problem that the organic light emitting layer deteriorates in a wet process for forming the color conversion filters. The organic light emitting layer is sensitively affected by the environment, in particular, moisture. Moisture promotes crystallization of the organic layer. Moisture also penetrates between the electrode and the organic light emitting layer and causes cleavage between them, thereby generating dark spots, in which light emission fails on voltage application. In the inversion structure, a cathode is formed on a glass substrate of the device. Since the cathode and the anode must be orthogonal, a process of patterning the cathode (photolithography process) is necessary. Cathode material of a metal or an alloy with low work-function such as Al--Li is oxidized and electron injection performance deteriorates, causing degradation of light emission efficiency of the device. [0017] To solve this problem, a method of manufacturing an organic EL device has been proposed (Japanese Unexamined Patent Application Publication No. 2001-93664). The method comprises a step of forming an organic light emitting element by laminating a cathode, an organic light emitting layer, and a transparent electrode on a first substrate, a step of forming a color conversion filter on a transparent second substrate, the filter receiving electroluminescence from the organic light emitting layer and emitting fluorescent light, and a step of arranging the first and the second substrates opposite to each other in such a way that the organic light emitting element and the color conversion filter are sandwiched by the substrates. [0018] Important performance for practical application to color display is long term stability of light emitting characteristics as well as precise color display performance (Refer to Kinou Zairyou: Vol. 18, No. 2, p 36-(published in 1998)). Nevertheless, organic EL devices have a drawback that light emitting performances including current-luminance characteristic significantly degrade after certain period of operation. [0019] Principal cause of the deterioration of light emission performance is growth of dark spots; the dark spot is a defect spot of light emission. The growth of dark spot proceeds along with progress of oxidation in the operating period and the storing period, and the dark spots expand towards whole of the light emission surface. [0020] The dark spot is considered to be originated from oxidation or aggregation of materials of the laminated layers of the light emitting element caused by oxygen or moisture contained in the element. The growth of dark spots proceeds in storage as well as in operation. The growth of dark spots specifically is: (a) accelerated by oxygen or moisture around the element; Continue reading... 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