Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2001-02-26
2004-12-07
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S917000, C428S212000, C313S504000, C313S506000, C313S112000, C313S113000, C257S098000
Reexamination Certificate
active
06828042
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a new organic electroluminescence device; a thin-film, light-weight and high definition organic electroluminescence device; new photoelectron devices using said devices, such as a thin-film flat panel display, small sized portable projection display, cellular phone display device, portable PC display, real-time electronic bulletin board, light emitting diode, laser, two-dimensional optical pattern generating device, optical computer, optical cross connector and optical router; as well as to the systems and services using them.
There has been a growing demand for a light-weight, high definition and less costly small-sized flat panel display for use in the various types of cellular phones, mobile terminals, mobile computers and car navigation systems being developed. For household and office use, a space saving desktop display, a flat panel display and wall-mounted TV sets are taking the place of conventional CRT tube displays. Especially, digital signal transmission on the order of hundreds to several gigabits/sec. has been put into commercial use in both wired and wireless methods, as a result of the increased use of the high-speed Internet and the progress of digital broadcasting. Time is shifting into an age where general users will exchange a huge amount of information on a real-time basis. Under these circumstances, flat panel displays are required to provide a higher speed display to permit digital processing, in addition to being still more light-weight, and having a higher definition, a higher luminance and a lower price.
The Liquid Crystal Display (LCD), Plasma Display (PD) and Field Emission Display (FED) are currently under study to meet these requirements. In addition to these flat panel displays, new types of flat panel display, referred to as Organic Electroluminescence Devices (OELD) or Organic Light Emitted Diodes (OLED), have begun to draw attention in recent years.
The organic electroluminescence device provides a method of causing fluorescent or phosphorescent organic molecules to emit light by allowing an electric current to flow to the organic compound sandwiched between a cathode and an anode, thereby displaying information. According to the References (“Major Issues of Organic LED Elements to be Solved and Practical Statistics” edited by the Organic Electronics Material Research Organization, Bunshin Publishing Co., mid-1999, P.1-11, and “Preface to Current Situation and Issues of Materials and Devices” by Yoshiharu SATO), organic electroluminescence devices have long been studied mainly with respect to semiconducting crystals, such asanthracene and perylene.
In 1987, Tang et. al. proposed a two-layered organic electroluminescence device laminated with a light emitting organic compound thin film and a hole transporting organic compound thin film (C. W. Tang and S. A. Van Slyke, Appl. Phys. Lett. 51, 913 in 1987). The starting point is that a dramatic improvement of light emitting characteristics is enabled (light emitting efficiency: 1.51 m/W, drive voltage; 10V and luminance: 1000 cd/m
2
). Since then, a pigment doping technique and high molecular OLED, low working function electrode, mask vacuum evaporation system, etc. have been studied.
In 1997, an organic electroluminescence device based on an electrical charge injection method, called a simple matrix system was partly put into commercial use. Further, a new organic electroluminescence device based on the electrical charge injection method, called an active matrix system is currently under study for development. Such an organic electroluminescence device is operated according to the following principle: A fluorescent or phosphorescent organic light emitting material is made into a thin film between a pair of electrodes, and electrons and holes are injected from positive and negative electrodes. In the organic light emitting material, the injected electron becomes an organic one-electron molecule (simply called an electron) entering the Lowest Unoccupied Molecular Orbital (LUMO) of a light emitting molecule. The injected hole becomes an organic one-hole molecule (simply called hole) entering the Highest Occupied Molecular Orbital (HOMO) of the light emitting molecule. In the organic material, they move toward the opposite electrode. In the middle of the movement, when an electron meets a hole, a singlet or triplet state of excitation of the light emitting molecule is formed. As it deactivates while radiating light, light is released.
Generally, many of the organic light emitting materials are those having a high quantum efficiency with respect to photoexcitation, as in the case of various laser pigments. If these materials are made to emit light by electrical charge injection, the electron and hole have a lower electrical charge transport performance since many organic compounds are insulators. A high voltage on the order of hundreds of volts was required in the initial organic electroluminescence device. However, using excellent electrical charge transporting performances of the organic electrophotographic photoconductor used as a photoconductor of a copying machine, a thin film is divided into two types according to function. One is the film used to transport an electrical charge (hole), and the other is the film used to emit light. This separation of functions of the thin films has improved the light emitting characteristics in the above-mentioned Tang's two-layered organic electroluminescence device.
Recently, a 3-layered organic electroluninescence device has been reported wherein the electron transport performance of another electrical charge is assigned to a third organic thin film. In addition, separated function type and multi-layered film type organic electroluminescence devices have been proposed, wherein thin films assigned to perform various functions are added; for example, an electrical charge injection layer is provided to improve the characteristics of injecting the hole and electron into the organic material and a hole stop layer to improve the probability of re-combination between the two. However, the basis for light emitting is light radiation in the process of deactivation in the state of excitation from the organic light emitting molecule contained in the organic light emitting layer. This basis remains unchanged.
According to the References (“Major Issues of Organic LED Elements to be Solved and Practical Statistics” edited by the Organic Electronics Material Research Organization, Bunshin Publishing Co., mid-1999, P.25-38, and Yuuji HAMADA, “Chapter 2. Current situation and issues of Light Emitting Material”), a great number of the fluorescent or phosphorescent organic light emitting materials are known to have been developed for a variety of purposes, such as ink, dye and scintillator materials. The organic electroluminescence devices are made of these organic light emitting materials. They can be broadly classified in terms of molecular weight into low molecular and high molecular types.
The low molecular type is formed into thin films according to a dry process, such as a vacuum evaporation method, while the high molecular type is formed into thin films according to the cast method. Failure in the formation of organic thin films is said to be one of the reasons why a highly efficient device could not be obtained as an organic electroluminescence device in earlier days before Tang. Conditions required especially for the low molecule type are as follows: (1) Production of a thin film (100 nm level) in the vacuum evaporation system, (2) maintainability of a uniform thin film structure after formation of the film (without segregation crystal), (3) fluorescent light quantum yield in the solid status, (4) appropriate carrier transport performance, (5) heat resistance, (6) easy refining, and (7) electrochemical stability, etc. Further, this type can be classified into two types according to the light emitting process, that is, the light emitting material where light is emitted by direct re-combination between elect
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Yamnitzky Marie
LandOfFree
Organic electroluminescence device and photoelectron device... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Organic electroluminescence device and photoelectron device..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Organic electroluminescence device and photoelectron device... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3274189