Patent Application
20090179208
This invention relates to an organic luminescence transistor device and a manufacturing method thereof. In more details, in a vertical type of organic luminescence transistor device, this invention relates to an organic luminescence transistor device and a manufacturing method thereof wherein a current control between an anode and a cathode is facilitated.
An organic electroluminescence device has a simple structure, so that it has been expected as a luminescence device for the next generation display that is thinner, lighter, larger area and less costly. Thus, recently, the organic electroluminescence device has been studied hard.
As a driving method for driving the organic electroluminescence device, an active-matrix type of filed effect transistor (FET) that uses a thin film transistor (TFT) is considered to be advantageous in terms of operational speed and power consumption. On the other hand, as a semiconductor material for forming the thin film transistor, inorganic semiconductor materials such as a silicon semiconductor or a chemical compound semiconductor have been studied, but recently, an organic thin film transistor (organic TFT) that uses an organic semiconductor material has been also studied hard. The organic semiconductor material has been expected as a semiconductor material of the next generation. However, the organic semiconductor material has problems of a lower charge-transfer level and of a higher resistance, compared with the inorganic semiconductor material.
Regarding the filed effect transistor, a vertical FET structured type of static induction transistor (SIT) wherein the structure thereof is vertically arranged is recognized to be advantageous because a channel width of the transistor can be shortened, the whole electrode of the surface thereof can be effectively used so that rapid response and/or power enhancement can be achieved, and interface effect can be made smaller.
Accordingly, recently, based on the above advantageous features of the static induction transistor (SIT), an organic luminescence transistor composed of such an SIT structure and an organic electroluminescence device structure has been studied to be developed (for example, Kazuhiro Kudo, “Current Conditions and Future Prospects of Organic Transistor”, J. Appl. Phys. Vol. 72, No. 9, pp. 1151-1156 (2003); JP-A-2003-324203 (in particular, claim 1); JP-A-2002-343578 (in particular, FIG. 23)).
As described above, in the composite type of organic luminescence transistor 101, the slit-like Schottky electrodes 105 are embedded in the hole-transfer layer 104. A Schottky barrier junction is formed between the hole-transfer layer 104 and the gate electrode 105, so that a depletion layer is formed in the hole-transfer layer 104. The expansion of the depletion layer is varied by the gate voltage (voltage applied between the source electrode 103 and the gate electrode 105). Thus, a channel width is controlled by varying the gate voltage, and an amount of generated charge is varied by controlling a voltage to be applied between the source electrode 103 and the drain electrode 107.
In the organic luminescence transistor composed of an SIT structure and an organic electroluminescence device structure, described in the above document and the above patent publications, with reference to
The present invention is accomplished in order to solve the aforementioned problems. An object of the present invention is to provide a vertical type of organic luminescence transistor device and a manufacturing method thereof wherein a current control between an anode and a cathode is facilitated.
The present invention is an organic luminescence transistor device comprising: a substrate; an assistance electrode layer provided on a side of an upper surface of the substrate; an insulation film provided on a side of an upper surface of the assistance electrode layer; a first electrode provided locally on a side of an upper surface of the insulation film, the first electrode covering an area of a predetermined size; an electric-charge-injection inhibiting layer provided on an upper surface of the first electrode, the electric-charge-injection inhibiting layer having the same size as the first electrode in a plan view; an electric-charge injection layer provided on the side of an upper surface of the insulation film at an area not provided with the first electrode and on an upper surface of the electric-charge-injection inhibiting layer; a luminescent layer provided on an upper surface of the electric-charge injection layer; and a second electrode layer provided on a side of an upper surface of the luminescent layer.
Alternatively, the present invention is an organic luminescence transistor device comprising: a substrate; an assistance electrode layer provided on a side of an upper surface of the substrate; an insulation film provided on a side of an upper surface of the assistance electrode layer; a first electrode provided locally on a side of an upper surface of the insulation film, the first electrode covering an area of a predetermined size; an electric-charge-injection inhibiting layer provided on an upper surface of the first electrode, the electric-charge-injection inhibiting layer having the same size as the first electrode in a plan view; an electric-charge injection layer provided on the side of an upper surface of the insulation film at an area not provided with the first electrode; a luminescent layer provided on an upper surface of the electric-charge-injection inhibiting layer and on an upper surface of the electric-charge injection layer; and a second electrode layer provided on a side of an upper surface of the luminescent layer.
Alternatively, the present invention is an organic luminescence transistor device comprising: a substrate; an assistance electrode layer provided on a side of an upper surface of the substrate; an insulation film provided on a side of an upper surface of the assistance electrode layer; a first electrode provided locally on a side of an upper surface of the insulation film, the first electrode covering an area of a predetermined size; an electric-charge-injection inhibiting layer provided on an upper surface of the first electrode, the electric-charge-injection inhibiting layer having the same size as the first electrode in a plan view; an electric-charge injection layer provided on the side of an upper surface of the insulation film at an area not provided with the first electrode; a luminescent layer provided on an upper surface of the electric-charge injection layer; and a second electrode layer provided on a side of an upper surface of the electric-charge-injection inhibiting layer and on a side of an upper surface of the luminescent layer.
According to the organic luminescence transistor device having any of the above structures, when a constant voltage is applied between the first electrode and the second electrode and a variable voltage is applied between the assistance electrode and the first electrode, an amount of luminescence can be controlled.
According to the organic luminescence transistor device having any of the above structures, since there is provided on the first electrode the electric-charge-injection inhibiting layer having the same size as the first electrode in a plan view, when a constant voltage is applied between the first electrode and the second electrode, generation of electric charges (positive holes or electrons) on an upper surface of the first electrode is inhibited, and the flow of the electric charges toward the second electrode is inhibited. For example, the electric charges generated at the first electrode are mainly generated at both edge surfaces (both lateral surfaces), each of which has a small area, not provided with the electric-charge-injection inhibiting layer. The thus generated electric charges are efficiently injected into the electric-charge injection layer which is adjacent to the both edge surfaces, and then flow (move) toward the second electrode. Thus, under a condition wherein a constant voltage is applied between the first electrode and the second electrode, a current value between the first electrode and the second electrode can be inhibited. As a result, by controlling the voltage to be applied between the assistance electrode and the first electrode, the electric current flowing between the first electrode and the second electrode can be controlled, so that the amount of the luminescence can be controlled.
In the above description, it is preferable that a thickness of the electric-charge injection layer is greater than a thickness of the first electrode. In the case, at least an edge portion of the first electrode comes in contact with the electric-charge injection layer, which is preferable. Furthermore, in the case, one or more luminescent layers may be formed between layered structures, each of which consists of the first electrode and the electric-charge-injection inhibiting layer, so as to form a matrix-patterned device. More specifically, it is preferable that a thickness of the electric-charge injection layer is substantially the same as or greater than a total thickness of the first electrode and the electric-charge-injection inhibiting layer.
In addition, a second electric-charge injection layer made of the same material as or a different material from the electric-charge injection layer may be provided between the insulation film and the first electrode and the electric-charge injection layer. In the case, the electric charges may be generated at a surface of the first electrode on a side of the insulation film as well. The flow of the electric charges generated at the surface of the first electrode on a side of the insulation film can be also controlled by the voltage to be applied between the assistance electrode and the first electrode, so that the electric current between the first electrode and the second electrode can be controlled, that is, the amount of the luminescence can be controlled.
In addition, it is preferable that a third electric-charge injection layer for the second electrode layer is provided between the luminescent layer and the second electrode layer. In the case, according to the same principle as the electric-charge injection layer provided adjacent to the first electrode, injection of the electric charges into the luminescent layer can be facilitated because of the third electric-charge injection layer provided adjacent to the second electrode.
Furthermore, in the case, it is preferable that an electric-charge transfer layer is provided between the luminescent layer and the third electric-charge injection layer, in order to improve performance of the electric-charge transfer.
In addition, the electric-charge-injection inhibiting layer is preferably made of an insulation material, more preferably a photoresist material. In the case, a forming step of the electric-charge-injection inhibiting layer on the first electrode is easy. In addition, accuracy of dimension in forming the electric-charge-injection inhibiting layer can be enhanced.
For example, the first electrode functions as an anode, and the second electrode functions as a cathode. Alternatively, the first electrode functions as a cathode, and the second electrode functions as an anode. Whichever polarity the first electrode and the second electrode have, the amount of the electric charges can be sensitively varied by controlling the voltage (gate voltage) to be applied between the assistance electrode and the first electrode. Thus, the electric current between the first electrode and the second electrode is controlled, so that the amount of the luminescence can be controlled sensitively.
In addition, the present invention is an organic luminescence transistor comprising: an organic luminescence transistor device having any of the above features; a first voltage-feeding unit configured to apply a constant voltage between the first electrode and the second electrode of the organic luminescence transistor device; and a second voltage-feeding unit configured to apply a variable voltage between the first electrode and the assistance electrode of the organic luminescence transistor device.
According to the present invention, by means of the first voltage-feeding unit and the second voltage-feeding unit, a constant voltage can be applied between the first electrode and the second electrode, and a variable voltage can be applied between the first electrode and the assistance electrode. As a result, the amount of the electric charges can be sensitively varied, so that the electric current between the first electrode and the second electrode is controlled and the amount of the luminescence can be controlled sensitively.
In addition, the present invention is a luminescence display apparatus comprising a plurality of luminescent parts arranged in a matrix pattern, wherein each of the plurality of luminescent parts has an organic luminescence transistor device having any of the above features.
According to the luminescence display apparatus, the amount of the luminescence can be easily controlled, so that the luminance can be easily adjusted.
In addition, the present invention is a manufacturing method of an organic luminescence transistor device, the manufacturing method comprising the steps of: preparing a substrate on which an assistance electrode layer and an insulation film has been formed in this order; providing a first electrode locally on a side of an upper surface of the insulation film such that the first electrode has a predetermined size in a plan view; providing an electric-charge-injection inhibiting layer on an upper surface of the first electrode such that the electric-charge-injection inhibiting layer has the same size as the first electrode in a plan view, the electric-charge-injection inhibiting layer being made of a (positive-type) photosensitive material that becomes removable by photoirradiation; providing an electric-charge injection layer on the side of an upper surface of the insulation film at an area not provided with the first electrode and on an upper surface of the electric-charge-injection inhibiting layer; providing a luminescent layer on an upper surface of the electric-charge injection layer; and providing a second electrode layer on a side of an upper surface of the luminescent layer; wherein in the step of providing the first electrode, as a material for forming the first electrode, a material that doesn't transmit an exposure wavelength of the photosensitive material is used; and the step of providing the electric-charge-injection inhibiting layer includes the steps of: providing the photosensitive material on the side of an upper surface of the insulation film at substantially the whole area so as to cover the first electrode, and exposing the photosensitive material to light from a side of the substrate so as to remove the photosensitive material on the side of an upper surface of the insulation film only at the area not provided with the first electrode.
Alternatively, the present invention is a manufacturing method of an organic luminescence transistor device, the manufacturing method comprising the steps of: preparing a substrate on which an assistance electrode layer and an insulation film has been formed in this order; providing a first electrode locally on a side of an upper surface of the insulation film such that the first electrode has a predetermined size in a plan view; providing an electric-charge-injection inhibiting layer on an upper surface of the first electrode such that the electric-charge-injection inhibiting layer has the same size as the first electrode in a plan view, the electric-charge-injection inhibiting layer being made of a photosensitive material that becomes removable by photoirradiation; providing an electric-charge injection layer on the side of an upper surface of the insulation film at an area not provided with the first electrode; providing a luminescent layer on an upper surface of the electric-charge-injection inhibiting layer and on an upper surface of the electric-charge injection layer; and providing a second electrode layer on a side of an upper surface of the luminescent layer; wherein in the step of providing the first electrode, as a material for forming the first electrode, a material that doesn't transmit an exposure wavelength of the photosensitive material is used; and the step of providing the electric-charge-injection inhibiting layer includes the steps of: providing the photosensitive material on the side of an upper surface of the insulation film at substantially the whole area so as to cover the first electrode, and exposing the photosensitive material to light from a side of the substrate so as to remove the photosensitive material on the side of an upper surface of the insulation film only at the area not provided with the first electrode.
Alternatively, the present invention is a manufacturing method of an organic luminescence transistor device, the manufacturing method comprising the steps of: preparing a substrate on which an assistance electrode layer and an insulation film has been formed in this order; providing a first electrode locally on a side of an upper surface of the insulation film such that the first electrode has a predetermined size in a plan view; providing an electric-charge-injection inhibiting layer on an upper surface of the first electrode such that the electric-charge-injection inhibiting layer has the same size as the first electrode in a plan view, the electric-charge-injection inhibiting layer being made of a photosensitive material that becomes removable by photoirradiation; providing an electric-charge injection layer on the side of an upper surface of the insulation film at an area not provided with the first electrode; providing a luminescent layer on an upper surface of the electric-charge injection layer; and providing a second electrode layer on a side of an upper surface of the electric-charge-injection inhibiting layer and on a side of an upper surface of the luminescent layer; wherein in the step of providing the first electrode, as a material for forming the first electrode, a material that doesn't transmit an exposure wavelength of the photosensitive material is used; and the step of providing the electric-charge-injection inhibiting layer includes the steps of: providing the photosensitive material on the side of an upper surface of the insulation film at substantially the whole area so as to cover the first electrode, and exposing the photosensitive material to light from a side of the substrate so as to remove the photosensitive material on the side of an upper surface of the insulation film only at the area not provided with the first electrode.
According to any of the above manufacturing methods of an organic luminescence transistor device, it is possible to form the electric-charge-injection inhibiting layer easily and precisely.
In any of the above manufacturing methods of an organic luminescence transistor device, it is preferable that the step of providing the electric-charge injection layer is carried out by a patterning process such as a mask deposition process or an ink-jetting method, and that the electric-charge injection layer is formed into a thickness not less than that of the first electrode. More specifically, when the electric-charge injection layer is formed of a low-molecular material, it is preferable that the pattern formation is carried out by a mask deposition method or the like. When the electric-charge injection layer is formed of a polymer (high-molecular) material, it is preferable that the pattern formation is carried out by an ink-jetting method or the like. According to these methods, the electric-charge injection layer may be formed between adjacent first electrodes to form a device. In addition, luminescent layers may be formed between adjacent layered structures, each of which consists of the first electrode and the electric-charge-injection inhibiting layer, to form a matrix-patterned device.
In addition, preferably, a step of providing a second electric-charge injection layer made of the same material as or a different material from the electric-charge injection layer on the upper surface of the insulation film is conducted, before the step of providing the first electrode.
In addition, the present invention is an organic transistor device comprising: a substrate; an assistance electrode layer provided on a side of an upper surface of the substrate; an insulation film provided on a side of an upper surface of the assistance electrode layer; a first electrode provided locally on a side of an upper surface of the insulation film, the first electrode covering an area of a predetermined size; an electric-charge-injection inhibiting layer provided on an upper surface of the first electrode, the electric-charge-injection inhibiting layer having the same size as the first electrode in a plan view; an organic semiconductor layer provided on the side of an upper surface of the insulation film at an area not provided with the first electrode; and a second electrode layer provided on a side of an upper surface of the organic semiconductor layer.
The preset invention is explained in detail based on embodiments thereof.
The embodiment shown in
Herein, in the present specification, the electric-charge injection layer 12 and the luminescent layer 11 may be integrally called an organic layer 6. If required, an electric-charge transfer layer (described below) may be included in the organic layer 6.
In the embodiment of
In the present embodiment (although the other embodiments are also the same), by applying a constant electric field (drain voltage VD) between the first electrode 4 and the second electrode 7 and by varying a gate voltage VG applied between the assistance electrode 2 and the first electrode 4, a generation amount of the electric charges can be controlled. The generated electric charges are carried to the luminescent layer 11, and reunite with electric charges supplied from the second electrode 7 so as to be made luminescent (to emit light). Thus, when the generation amount of the electric charges is controlled, an amount of the luminescence is controlled.
This control for the amount of the luminescence can be achieved by the fact that the electric-charge-injection inhibiting layer 5 is provided on the first electrode 4. As shown in
Regarding polarity of the electrodes, the first electrode 4 may be structured as an anode, and the second electrode 7 may be structured as a cathode. Alternatively, the first electrode 4 may be structured as a cathode, and the second electrode 7 may be structured as an anode. Whichever polarity the first electrode 4 and the second electrode 7 have respectively, the amount of the electric charges can be sensitively varied by controlling the voltage applied between the assistance electrode 2 and the first electrode 4. Thus, the electric current between the first and second electrodes can be controlled, so that the amount of the luminescence can be controlled.
Herein, when the first electrode 4 is an anode and the second electrode 7 is a cathode, the electric-charge injection layer adjacent to the first electrode 4 is a positive-hole injection layer. Then, if another electric-charge injection layer 14 (third electric-charge injection layer) adjacent to the second electrode 7 is provided (see
The important features are that the first electrode 4 is formed on a side of the upper surface of the insulation film 3 (a second electric-charge injection layer may be provided therebetween: see
For example, regarding the structural form of the organic layer 6 having the electric-charge injection layer 12 and the luminescent layer 11; (i) as shown in
In addition, for example, as shown in
Regarding the layered form of the organic layer 6, for example; as shown in
As described above, in the respective embodiments shown in
The organic luminescence transistor devices of the respective embodiments may be top-emission type of luminescence (Light-Emitting) transistor devices or bottom-emission type of luminescence transistor devices. Light transmittance of each layer is designed depending on which type is adopted. Each sectional view of the organic luminescence transistor device corresponds to one pixel of an organic luminescence transistor. Thus, if a luminescent layer is formed to emit a predetermined color light for each pixel, a color display or the like may be formed as a luminescent display apparatus.
In addition, as shown in
Layers and electrodes included in the organic luminescence transistor devices of the respective embodiments are explained below.
The substrate 1 is not particularly limited, but may be suitably selected depending on materials or the like of layers to be laminated. For example, it may be selected from various materials such as metal, for example aluminum, glass, quartz, or resin. In the case of an organic luminescence transistor device having a bottom-emission structure, which emits light from a side of the substrate, it is preferable that the substrate is formed of a transparent or semitransparent material. On the other hand, in the case of an organic luminescence transistor device having a top-emission structure, which emits light from a side of the second electrode 7, it is not necessary to use a transparent or semitransparent material. That is, the substrate 1 may be formed of an opaque material.
More preferably, it is possible to use various materials that have been generally used as a substrate of an organic EL device. For example, depending on the application, flexible materials or rigid materials or the other may be selected. Specifically, there can be used substrates made from such materials as glass, quartz (silica), polyethylene, polypropylene, polyethylene terephthalate, polymethacrylate, polymethyl methacrylate, polymethyl acrylate, polyester, and polycarbonate.
The substrate 1 may have an individual shape or a continuous shape (a film or a SUS roll (thin SUS roll)). Specifically, a card-patterned shape, a film-like shape, a disk-like shape, and so on may be given as an example.
As electrodes, there are provided the assistance electrode 2, the first electrode 4 and the second electrode 7. As materials for the respective electrodes, a metal, a conductive oxide, a conductive polymer or the like may be used.
The first electrode 4 is locally provided on the side of the upper surface of the insulation film 3 in a predetermined size. The predetermined size is not particularly limited. As an example, there is provided a comb-shaped electrode 4 having a line-width of about 1 to 500 μm and a line-pitch of about 1 to 500 μm, (which is shown as a layered structure 8 in
Examples of materials useful for forming the assistance electrode 2 include electrically-conductive transparent films such as films of ITO (indium tin oxide), indium oxide, IZO (indium zinc oxide), SnO2, and ZnO; metallic materials having great work functions, such as gold and chromium; general metallic materials, such as silver and aluminum; and electrically-conductive polymers such as polyaniline, polyacetylene, polyalkylthiophene derivatives, and polysilane derivatives. The assistance electrode 2 is provided on the side of the upper surface of the substrate 1. A barrier layer and/or a smoothing layer may be provided between the substrate 1 and the assistance layer 2.
Examples of materials useful for forming the first electrode 4 or the second electrode 7 as a cathode include single metallic materials such as aluminum and silver; magnesium alloy, such as MgAg; aluminum alloy, such as AlLi, AlCa, and AlMg; alkali metallic materials, such as Li and Ca; alkali metallic alloy, such as LiF; and other metallic materials having small work functions.
On the other hand, examples of materials useful for forming the first electrode 4 or the second electrode 7 as an anode include, among the electrode-forming materials useful for the auxiliary electrode 2 and for the above-described cathode, metals that produce “ohmic contact” with some material of the organic layer (the charge injection layer or the luminescent layer) in contact with the anode. Preferred examples of such materials include metallic materials having great work functions, such as gold and chromium; electrically-conductive transparent films such as films of ITO (indium tin oxide), indium oxide, IZO (indium zinc oxide), SnO2, and ZnO; and electrically-conductive polymers such as polyaniline, polyacetylene, polyalkylthiophene derivatives, and polysilane derivatives.
Each of the assistance electrode 2, the first electrode 4 and the second electrode 7 may be a single-layered electrode made of any of the above materials, or a multi-layered electrode made of a plurality of the above materials.
Herein, as described below, when a photosensitive material that becomes removable by photoirradiation is used as a material for the electric-charge-injection inhibiting layer 5, a material that doesn't transmit an exposure wavelength of the photosensitive material is preferably used as a material for the first electrode 4, and a material that transmits the exposure wavelength of the photosensitive material is preferably used as a material for the assistance electrode 2.
The thickness of each electrode is not limited, but usually within a range of 10 to 1000 nm.
When the organic luminescence transistor device is a bottom-emission type, it is preferable that the electrodes located below the luminescent layer 11 are transparent or semitransparent. On the other hand, when the organic luminescence transistor device is a top-emission type, it is preferable that the electrodes located above the luminescent layer 11 are transparent or semitransparent. As a transparent electrode material, any of the above electrically-conductive transparent films, thin metallic films, and electrically-conductive polymer films may be used. Herein, the “below” and the “above” are defined in a vertical direction in the plane of the drawings.
The above respective electrodes are formed by a vacuum process such as vacuum deposition, sputtering or CVD, or a coating process. The thickness (film thickness) of each electrode depends on the material used for the electrode. For example, it is preferable that the thickness is within a range of about 10 nm to about 1000 nm. Herein, when an electrode is formed on the organic layer such as the luminescent layer 11 and/or the electric-charge injection layer 12, a protecting layer (not shown) may be provided on the organic layer, in order to reduce damage of the organic layer at the formation of the electrode. The protection layer may be provided before the electrode is formed, in a case wherein the electrode is formed on the organic layer by a sputtering method or the like. For example, a vacuum deposition film or a sputtering film is preferably formed by a semitransparent film made of Au, Ag, Al, or the like, or by an inorganic semiconductor film made of ZnS, ZnSe, or the like, which scarcely gives damage to the organic layer when the film is formed. The thickness of the protection layer is preferably within a range of about 1 to about 500 nm.
The insulating layer 3 is formed on the assistance (auxiliary) electrode 2. The insulating layer 3 can be formed from an inorganic material such as SiO2, SiNx or Al2O3, an organic material such as polychloroprene, polyethylene terephthalate, polyoxymethylene, polyvinyl chloride, polyvinylidene fluoride, cyanoethyl pullulan, polymethyl methacrylate, polyvinyl phenol, polysulfone, polycarbonate or polyimide, or a commercially available resist material that is commonly used in this field. The insulation film 3 may be a single-layered insulation film made of any of the above materials, or a multi-layered insulation film made of a plurality of the above materials. Herein, as described below, when a photosensitive material that becomes removable by photoirradiation is used as a material for the electric-charge-injection inhibiting layer 5, a material that transmits the exposure wavelength of the photosensitive material is preferably used as a material for the insulation film 3.
In particular, in the present invention, in view of manufacturing cost and/or manufacturing easiness, it is preferable to use a resist material commonly used in this field. A predetermined pattern may be formed by a screen printing method, a spin coating method, a cast method, a Czochralski method, a decalcomania method, an ink-jetting method, a photolithography method, or the like. The insulation film 3 made of the above inorganic material may be formed by an existing patterning process such as a CVD. It is preferable that the thickness of the insulation film 3 is thinner. However, if the thickness is too thin, leakage electric current between the assistance electrode 2 and the first electrode 4 tends to become great. Thus, the thickness is usually within a range of about 0.001 μm to 5.0 μm.
When the organic luminescent transistor device is the bottom-emission type, the insulation film 3 is located below the luminescent layer 11. Thus, the insulation film 3 is preferably transparent or semitransparent. On the other hand, when the organic luminescent transistor device is the top-emission type, it is unnecessary that the insulation film 3 is transparent or semitransparent.
The electric-charge-injection inhibiting layer 5 is provided on the first electrode 4, and functions to inhibit the flow of the electric charges (positive holes or electrons) generated at the upper surface of the first electrode 4, which is opposite to the second electrode 7, toward the second electrode 7. In the present invention, the electric-charge-injection inhibiting layer 5 is provided on the upper surface of the first electrode 4, which is opposite to the second electrode 7. Thus, the electric charges (flow of the electric charges) are mainly generated at the edge portion 4a, which has only a small area and is not covered by the electric-charge-injection inhibiting layer 5. The amount of the generated electric charges (flow of the electric charges) at the edge portion 4a of the first electrode 4 is controlled by the gate voltage VG applied between the assistance electrode 2 and the first electrode 4. In addition, the electric charges (flow of the electric charges) generated at the edge portion 4a moves toward the second electrode 7 by means of the drain voltage VD applied between the first electrode 4 and the second electrode 7. Thus, by controlling the gate voltage VG applied between the assistance electrode 2 and the first electrode 4, the electric current flowing between the first electrode 4 and the second electrode 7 may be controlled. Thus, the luminescence amount may be controlled.
The electric-charge-injection inhibiting (suppression) layer 5 can be formed from any of a variety of materials, as long as it can exhibit the above-described effects. Examples of films useful for the electric-charge-injection inhibiting (suppression) layer 5 include inorganic or organic insulating films. For example, the electric-charge-injection inhibiting (suppression) layer 5 may be a film of an inorganic insulating material such as SiO2, SiNx or Al2O3, or of a conventional organic insulating material such as polychloroprene, polyethylene terephthalate, polyoxymethylene, polyvinyl chloride, polyvinylidene fluoride, cyanoethyl pullulan, polymethyl methacrylate, polyvinyl phenol, polysulfone, polycarbonate or polyimide. The electric-charge-injection inhibiting (suppression) layer 5 may be a single-layered electric-charge-injection inhibiting layer made of any of the above materials, or a multi-layered electric-charge-injection inhibiting layer made of a plurality of the above materials. The electric-charge-injection inhibiting layer 5 is formed by a vacuum process such as vacuum deposition, sputtering or CVD, or a coating process. The thickness of the electric-charge-injection inhibiting layer 5 depends on the material used for the electric-charge-injection inhibiting layer 5. For example, it is preferable that the thickness is within a range of about 0.001 μm to about 10 μm.
It is preferable that the electric-charge-injection inhibiting layer 5 is made of an insulation material which is easily available, easily formable, and easily capable of precisely patterning. In particular, it is preferable to use a film made of a photosensitive material that becomes removable by photoirradiation, more specifically a positive-type resin film. When a positive-type photosensitive material is used as a material for the electric-charge-injection inhibiting layer 5, the photosensitive material is provided on the insulation film 3 so as to cover the first electrode 4, and then is exposed to light from a side of the substrate 1. Thus, only the positive-type photosensitive material provided between the first electrodes 4 may be removed easily and precisely. As a result, the electric-charge-injection inhibiting layer 5 having the same size as the first electrode 4 in a plan view may be formed on the first electrode 4 accurately in dimension.
The electric-charge-injection inhibiting layer 5 is formed, at least, on the upper surface of the first electrode 4, which is opposite to the second electrode 7. Herein, the edge portion 4a of the first electrode 4 is arranged in contact with the electric-charge injection layer 12. In order to satisfy this requirement, it is preferable that the electric-charge-injection inhibiting layer 5 is formed on the first electrode 4 such that the electric-charge-injection inhibiting layer 5 has the same size as the first electrode 4 in a plan view. Herein, “the same size” includes not only completely the same size but also a size achievable the common effect. Since the above electric-charge-injection inhibiting layer 5 is formed, the electric charges (flow of the electric charges) are not generated at the upper surface of the first electrode 4, which is opposite to the second electrode 7. However, the electric charges (flow of the electric charges) are generated at the edge portion 4a of the small area. As a result, by controlling the voltage (gate voltage) applied between the assistance electrode 2 and the first electrode 4, the amount of the generated electric charges (generated positive holes) is sensitively changed. This, the electric current between the first and second electrodes can be controlled, so that the amount of the luminescence can be controlled.
As described above, the organic layer 6 includes, at least, the electric-charge injection layer 12 and the luminescent layer 11. If required, an electric-charge transfer layer or the like may be added. Alternatively, the organic layer 6 may include a luminescent layer 11 including an electric-charge injecting material. As long as these requirements are satisfied, the organic layer 6 is not particularly limited. That is, the above respective manners may be adopted. Each layer as a component of the organic layer 6 is formed in a suitable thickness (for example, within a range of 0.1 nm to 1 μm), depending on a structure of the device and/or a kind of the material. Herein, if the thickness of each layer of the organic layer is too large, a large voltage may be necessary in order to obtain a predetermined light emission, which is inferior in light-emission efficiency. On the other hand, if the thickness of each layer of the organic layer is too small, a pinhole or the like may be generated, which results in insufficient luminance (brightness) when the electric field is applied.
Any material that is commonly used as a luminescent layer in an organic EL device is useful for the luminescent layer 11. For example, a pigment luminescent material, a metal complex luminescent material, a polymer luminescent material, or the like may be used.
Examples of luminescent pigments include cyclopentadiene derivatives, tetraphenyl butadiene derivatives, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, silol derivatives, thiophene cyclic compounds, pyridine cyclic compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, trifumanylamine derivatives, oxadiazole dimers, and pyrazoline dimers. Examples of luminescent metal complexes include alumiquinolinol complexes, benzoquinolinol beryllium complexes, benzoxazole zinc complexes, benzothiazole zinc complexes, azomethyl zinc complexes, porphyrin zinc complexes, and europium complexes. Other examples of luminescent metal complexes include metal complexes having, as a central metal, such a metal as Al, Zn or Be, or a rare earth metal such as Tb, Eu or Dy, and, as a ligand, oxadiazole, thiadiazole, phenylpyridine, phenylbenzoimidazole, or quinoline structure. Examples of luminescent polymers include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyvinyl carbazole, polyfluorenone derivatives, polyfluorene derivatives and polyquinoxaline derivatives, and copolymers of these derivatives.
Additives such as a dopant may be added to the luminescent layer 11 for the purpose of improving light emission efficiency or of changing emission wavelength. Examples of dopants useful herein include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squaleum derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazoline derivatives, decacyclene, phenoxazone, quinoxaline derivatives, carbazole derivatives, and fluorene derivatives.
Examples of materials useful for forming the electric-charge injection layer 12 include the compounds enumerated above as examples of luminescent materials. Other materials useful for the electric-charge injection layer 12 include phenylamines, starburst amines, phthalocyanines, polyacenes, oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide and aluminum oxide, and derivatives of amorphous carbon, polyaniline, polythiophene, etc.
An electric-charge injection layer 14 for the second electrode (see
Examples of materials that can be used to form the electric-charge (hole) transfer layer 13 (see
Further, although not shown in the figures, an electric-charge transfer layer may be formed on the second electrode 7 side of the luminescent layer 11. Examples of materials that can be used to form this electric-charge (electron) transfer layer when the second electrode 7 serves as a cathode include those materials that are commonly used as electron transfer materials, such as anthraquinodimethane, fluorenylidene methane, tetracyanoethylene, fluorenone, diphenoquinone oxadiazole, anthrone, thiopyrane dioxide, diphenoquinone, benzoquinone, marononitrile, dinitrobenzene, nitroanthraquinone, maleic anhydride, and perylene tetracarboxylic acid, and derivatives of these compounds. An electric-charge-transfer-layer-forming coating liquid containing any of the above-enumerated compounds is used to form the electric-charge (electron) transfer layer. The electric-charge transfer material may be incorporated into the luminescent layer 11 or into the charge injection layer 12.
A luminescent material or electric-charge transfer/injection material, such as an oligomeric or dendrimeric material, can be incorporated in the organic layer composed of the luminescent layer 11, the charge injection layer 12, the electric-charge transfer layer 13, etc., as needed. To form each layer constituting the organic layer, a vacuum deposition process is used. Alternatively, a coating liquid prepared by dissolving or dispersing the material for forming each layer in such a solvent as toluene, chloroform, dichloromethane, tetrahydrofuran, or dioxane is applied with an applicator or the like, or is printed, to form each layer.
As described above, the organic layer 6 is formed by the luminescent-layer forming material, the electric-charge-injection-layer forming material, electric-charge-transfer-layer forming material, and/or the like, depending on the respective layered (laminated) manners. Herein, the organic layer 6 is divided by partitions (not shown), and formed at each predetermined position. The partitions (not shown) form areas divided for respective emission colors in the plane of the luminescent display apparatus including the organic luminescent transistor device. As a material for the partitions, any conventional material that is commonly used as a partition material may be used, for example a photosensitive resin, an active energy beam curable resin, a heat curable resin, a thermoplastic resin or the like. As a forming method of the partitions, a suitable method for the adopted partition material is adopted. For example, a thick-film printing method or a patterning method to a photosensitive resin may be used to form the partitions.
In the embodiment shown in
Next, embodiments of a manufacturing method of an organic luminescence transistor device according to the present invention are explained.
The manufacturing method of an organic luminescence transistor device according to the present embodiment comprises, at least, the steps of: preparing a substrate 1 on which an assistance electrode layer 2 and an insulation film 3 has been formed in this order (see
Among the above steps, in the step of forming the electric-charge-injection inhibiting layer 5 on the first electrode 4, as a material for the electric-charge-injection inhibiting layer 5, the various materials as described above may be used. Preferably, as a material for the electric-charge-injection inhibiting layer 5, a photosensitive material (positive-type resist) that becomes removable by photoirradiation may be used. In the case, it is preferable to use a material that doesn't transmit an exposure wavelength of the photosensitive material, as a material for the first electrode 4. After the photosensitive material is provided on the whole area of the insulation film 3 so as to cover the first electrode 4 (see
The material that doesn't transmit an exposure wavelength of the photosensitive material includes a metal such as Al, Au, Cr, Pt and Ti, and a transparent electrode made of ITO or IZO whose upper surface or lower surface is laminated with Au, Al or the like. When the first electrode 4 made of one of these materials is an anode, it is preferable that the first electrode 4 includes one layer made of a material that is easy to inject electric charges (positive holes) into the electric-charge (positive-hole) injection layer in contact with the first electrode 4, specifically, Au, Cr, Pt, Ti, ITO or IZO. On the other hand, when the first electrode 4 is a cathode, it is preferable that the first electrode 4 includes one layer made of a material that is easy to inject electric charges (electrons) into the electric-charge (electron) injection layer in contact with the first electrode 4
That is, as shown in
When the organic luminescence transistor device 20A shown in
When the organic luminescence transistor device 20B shown in
When the organic luminescence transistor device 20C shown in
In the manufacturing method for the organic luminescent transistor devices shown in
As described in the explanation regarding
Organic luminescent transistor devices shown in
According to the above manufacturing method, when the electric-charge-injection inhibiting layer 5 is formed on the first electrode 4, the positive-type photosensitive material is provided so as to cover the first electrode 4 and then is exposed to light from a side of the substrate 1. Thus, only the positive-type photosensitive material provided on the insulation film 3 between the first electrodes 4, 4 may be removed easily and precisely.
Next, embodiments of an organic luminescence transistor and a luminescence display apparatus are explained. The present invention is not limited by the following explanation.
In the organic luminescence transistor of the present embodiment, a plurality of organic luminescence transistor devices is arranged in a matrix pattern on a sheet-like substrate. The organic luminescence transistor of the present embodiment comprises: the plurality of organic luminescence transistor devices, a first voltage-feeding unit configured to apply a constant voltage (drain voltage VD) between the first electrode 4 and the second electrode 7 of each organic luminescence transistor device, and a second voltage-feeding unit configured to apply a variable voltage (gate voltage VG) between the first electrode 4 and the assistance electrode 2 of each organic luminescence transistor device.
In the luminescence display apparatus of the present embodiment, a plurality of luminescent parts is arranged in a matrix pattern. Each of the plurality of luminescent parts has an organic luminescence transistor device having the feature of the present invention.
Each pixel 180 shown in
As shown in
Next, an operation of the circuit shown in
In the same manner as the case shown in
As shown in
Next, an operation of the circuit shown in
The image-signal feeding source 163 shown in
A color-image display apparatus can be obtained when adjacent small pixels respectively emit RGB three colors, that is, a red-based color, a green-based color and a blue-based color.
Examples and comparisons are explained below.
An insulation film 3 was formed of a PVP-based resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10), into a 300 nm thickness, by means of a spin coating method, on a glass substrate 1 having an assistance electrode 2 that is made of an ITO film and has a 100 nm thickness.
Next, by means of a vacuum deposition method using a mask, a first electrode 4 (anode) was formed of Au (whose thickness was 30 nm). Then, in order to cover the first electrode 4, the positive-type resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10) was applied on the insulation film 3 by means of a spin coating method. Then, an exposing light including wavelengths of 405 nm and 436 nm is irradiated from a side of the substrate 1, so as to expose the positive-type resist film between the first electrodes 4 (anodes) to the light. Then, the positive-type resist film was developed with an alkali development liquid (trade made: NMD-3). Thus, the resist film (whose thickness was 100 nm) as the electric-charge injection inhibiting layer 5 was formed only on the first electrode 4, and the other parts of the resist film was removed.
Then, pentacene (50 nm in thickness) was deposited as the electron-charge (positive hole) injection layer 12, by means of a vacuum deposition method, on the insulation film 3 between the laminated structures 8, each of which consists of the first electrode 4 and the electric-charge injection inhibiting layer 5. Then, α-NPD (40 nm in thickness) was deposited as an electric-charge (positive hole) transfer layer 13, by means of a vacuum deposition method, so as to cover the electric-charge injection layer 12 and the electric-charge-injection inhibiting layer 5. Furthermore, Alq3 (60 nm in thickness) as a luminescent layer 11/Lif (1 nm in thickness) as an electron injection layer 14/Al (100 nm in thickness) as a second electrode 7 were layered (laminated) in this order by means of a vacuum deposition method. Thus, an organic luminescent transistor device of the example 1 as shown in
While a voltage of minus 10 V (drain voltage VD) was applied between the first electrode 4 and the second electrode 7 of the organic luminescent transistor device of the example 1, another voltage (gate voltage VG) applied between the assistance electrode 2 and the first electrode 4 was varied.
As a result of
An insulation film 3 was formed of a PVP-based resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10), into a 300 nm thickness, by means of a spin coating method, on a glass substrate 1 having an assistance electrode 2 that is made of an ITO film and has a 100 nm thickness.
Next, by means of a vacuum deposition method using a mask, pentacene (50 nm in thickness) as the electron-charge (positive hole) injection layer 12′/Au (30 nm in thickness) as the first electrode 4 (anode)/SiO2 (100 nm in thickness) as the electron-charge (positive hole) injection inhibiting layer 5/pentacene (50 nm in thickness) as the electron-charge (positive hole) injection layer 12 between the laminated structures 8 each of which consists of the first electrode 4 and the electron-charge injection inhibiting layer 5/α-NPD (90 nm in thickness) as the electric-charge (positive hole) transfer layer 13/Alq3 (60 nm in thickness) as a luminescent layer 11/Lif (1 nm in thickness) as an electron injection layer 14/Al (100 nm in thickness) as a second electrode 7 were layered (laminated) in this order. Thus, an organic luminescent transistor device of the example 2 as shown in
The change of the luminescence of the organic luminescent transistor device of the example 2 was measured in the same manner as the example 1.
As a result of
An insulation film 3 was formed of a PVP-based resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10), into a 300 nm thickness, by means of a spin coating method, on a glass substrate 1 having an assistance electrode 2 that is made of an ITO film and has a 100 nm thickness.
Next, by means of a vacuum deposition method using a mask, a first electrode 4 (anode) was formed of Au (whose thickness was 30 nm). Then, in order to cover the first electrode 4, the positive-type resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10) was applied on the insulation film 3 by means of a spin coating method. Then, an exposing light including wavelengths of 405 nm and 436 nm is irradiated from a side of the substrate 1, so as to expose the positive-type resist film between the first electrodes 4 (anodes) to the light. Then, the positive-type resist film was developed with an alkali development liquid (trade made: NMD-3). Thus, the resist film (whose thickness was 100 nm) as the electric-charge injection inhibiting layer 5 was formed only on the first electrode 4, and the other parts of the resist film was removed.
Then, a poly(3-hexylthiophene) (80 nm in thickness) was deposited as the electron-charge (positive hole) injection layer 12, by means of an ink-jetting method, on the insulation film 3 between the laminated structures 8, each of which consists of the first electrode 4 and the electric-charge injection inhibiting layer 5. Then, α-NPD (40 nm in thickness) was deposited as an electric-charge (positive hole) transfer layer 13, by means of a vacuum deposition method, so as to cover the electric-charge injection layer 12 and the electric-charge-injection inhibiting layer 5. Furthermore, Alq3 (60 nm in thickness) as a luminescent layer 11/Lif (1 nm in thickness) as an electron injection layer 14/Al (100 nm in thickness) as a second electrode 7 were layered (laminated) in this order by means of a vacuum deposition method. Thus, an organic luminescent transistor device of the example 3 was manufactured. The sectional structure of the example 3 is similar to the sectional structure of the example 1 shown in
An insulation film 3 was formed of a PVP-based resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10), into a 300 nm thickness, by means of a spin coating method, on a glass substrate 1 having an assistance electrode 2 that is made of an ITO film and has a 100 nm thickness.
Next, by means of a vacuum deposition method using a mask, pentacene (50 nm in thickness) was deposited as the electron-charge (positive hole) injection layer 12′ and Au (30 nm in thickness) was deposited as the first electrode 4 (anode) in this order. Then, in order to cover the first electrode 4, the positive-type resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10) was applied on the electron-charge injection layer 12′ by means of a spin coating method. Then, an exposing light including wavelengths of 405 nm and 436 nm is irradiated from a side of the substrate 1, so as to expose the positive-type resist film between the first electrodes 4 (anodes) to the light. Then, the positive-type resist film was developed with an alkali development liquid (trade made: NMD-3). Thus, the resist film (whose thickness was 100 nm) as the electric-charge injection inhibiting layer 5 was formed only on the first electrode 4, and the other parts of the resist film was removed.
Then, pentacene (80 nm in thickness) was deposited as the electron-charge injection layer 12, by means of a mask vacuum deposition method, on the electron-charge injection layer 12′ between the laminated structures 8, each of which consists of the first electrode 4 and the electric-charge injection inhibiting layer 5. Then, α-NPD (40 nm in thickness) as the electric-charge transfer layer 13/Alq3 (60 nm in thickness) as a luminescent layer 11/Lif (1 nm in thickness) as an electron injection layer 14/Al (100 nm in thickness) as a second electrode 7 were layered (laminated) in this order by means of a vacuum deposition method. Thus, an organic luminescent transistor device of the example 4 was manufactured. The sectional structure of the example 4 is similar to the sectional structure of the example 2 shown in
An insulation film 3 was formed of a PVP-based resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10), into a 300 nm thickness, by means of a spin coating method, on a glass substrate 1 having an assistance electrode 2 that is made of an ITO film and has a 100 nm thickness.
Next, by means of a vacuum deposition method using a mask, a first electrode 4 (anode) was formed of Au (whose thickness was 30 nm). Then, in order to cover the first electrode 4, the positive-type resist (manufactured by TOKYO OHKA KOGYO CO. Ltd., trade name: TMR-P10) was applied on the insulation film 3 by means of a spin coating method. Then, an exposing light including wavelengths of 405 nm and 436 nm is irradiated from a side of the substrate 1, so as to expose the positive-type resist film between the first electrodes 4 (anodes) to the light. Then, the positive-type resist film was developed with an alkali development liquid (trade made: NMD-3). Thus, the resist film (whose thickness was 300 nm) as the electric-charge injection inhibiting layer 5 was formed only on the first electrode 4, and the other parts of the resist film was removed.
Then, a poly(3-hexylthiophene) (80 nm in thickness) was deposited as the electron-charge injection layer 12, by means of a spin coating method, on the insulation film 3 between the laminated structures 8, each of which consists of the first electrode 4 and the electric-charge injection inhibiting layer 5. Then, Au (70 nm in thickness) was deposited as the second electrode 7, by means of a vacuum deposition method. Thus, an organic luminescent transistor device of the example 5 was manufactured. The sectional structure of the example 5 is the sectional structure shown in
An organic luminescent transistor device of the comparison 1 was manufactured in the same manner as the example 2, except that SiO2 as the electron-charge injection inhibiting layer 5 was not deposited.
An organic transistor device of the comparison 2 was manufactured in the same manner as the example 5, except that positive-type resist as the electron-charge injection inhibiting layer 5 was not provided.
In
From
Herein, the above measurement was conducted under the following measurement condition: in a glove box; in an Ar atmospheric gas; and not more than 0.1 ppm of moisture and/or oxygen density, by means of a source meter made by KEITHLEY (trade name: 6430).
In
In
Herein, the above measurement was also conducted under the following measurement condition: in a glove box; in an Ar atmospheric gas; and not more than 0.1 ppm of moisture and/or oxygen density, by means of a source meter made by KEITHLEY (trade name: 6430).
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-341617 | Nov 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/323706 | 11/28/2006 | WO | 00 | 7/23/2008 |
