Display element

Display element

The present invention relates to a display element used in a color display and the like, and particularly relates to a self-luminous display element provided with an organic layer.

FIG. 15 shows an example of the configuration of a self-luminous display element (organic electroluminescence element) provided with an organic layer. The display element 1 shown in this figure is arranged on a transparent substrate 2 composed of, for example, glass. The display element 1 is an anode 3 composed of ITO (Indium Tin Oxide: transparent electrode) provided on a substrate 2, an organic layer 4 provided on the anode 3, and a cathode further provided on the upper part. 5 constituted. The organic layer 4 is constituted by stacking sequentially from the anode side, for example, a hole injection layer 4a, a hole transport layer 4b, and an electron-transporting light-emitting layer 4c. In the display element 1 thus constructed, light is taken out from the substrate 2 side, which is generated when the electrons injected from the cathode and the holes injected from the anode are recombined in the light-emitting layer 4c.

The lifespan of the organic electroluminescent device is generally determined by the injected charge, which can be solved by reducing the initial brightness of the drive. However, lowering the initial brightness will limit the applicability of practical applications, deny the potential of organic electroluminescent devices, and fail to realize the next generation of TVs.

In order to solve this problem, it is necessary to implement a device configuration that can increase the brightness without changing the drive current, that is, improve the efficiency, or even if the drive current is reduced, the same brightness can still be obtained.

Therefore, a stacked multi-photon emitting element (MPE element) in which a plurality of organic light-emitting elements are overlapped is proposed. Among them, a structure of an MPE element (display element 1') is also proposed. As shown in FIG. 16, between the anode 3 and the cathode 5, there is an insulating charge generation layer 6, which will be composed of an organic light-emitting layer 4c. A plurality of light-emitting units 4-1, 4-2, ... are arranged overlappingly composed of layers. Here, the charge generation layer 6 is used to inject holes into the light emitting unit 4-2 arranged on the cathode 5 side of the charge generation layer 6 when an electric field is applied, and on the other hand, for the anode arranged on the charge generation layer 6 The light-emitting unit on the 3 side 4-1 is the layer for injecting electrons, using vanadium oxide (V₂O₅) Or rhenium heptaoxide (Re₂O₇) And other metal oxides.

In addition, in order to improve the electron injection efficiency from the charge generation layer 6 to the light-emitting element 4-1 on the anode 3 side, an electron injection layer 7 as an "in-situ reaction generation layer" can be provided on the anode 3 side of the charge light-emitting layer 6. As the electron injection layer 7 of the "in-situ reaction generation layer", for example, a mixed layer of a cluster copolymer (Bathocuproin (BCP)) and metal cesium (Cs), or (8-hydroxyquinoline) lithium aluminum is used. Laminated body of compound and aluminum.

In the stacked organic electroluminescence element in which the light-emitting units 4-1, 4-2,... are stacked via the charge generating layer 6 as described above, when two light-emitting units are stacked, the luminous efficiency is ideally not changed [1 m/W] The brightness [cd/A] is doubled. When three light-emitting units are stacked, ideally the brightness [cd/A] can be tripled without changing the luminous efficiency [1 m/W] (refer to JP 2003-45676 above) No. Bulletin, Special Publication No. 2003-272860).

However, in the display element 1'composed of the light-emitting units 4-1 and 4-2 laminated via the charge generation layer 6 described in FIG. The material of the electron injection layer 7 is very unstable. Therefore, the stoichiometric ratio of the materials constituting the electron injection layer 7 is very important. If this balance is broken, the layer may become unstable.

For example, when BCP is rich in complex formation energy and has free metal components, or when organic materials with active parts exist, it is highly likely to form complexes with surrounding materials. If the stability of the device is considered, it will be difficult use. In addition, when using BCP components, lack of reliability for environmental tolerance may also be a problem.

Moreover, for this type of stacked organic electroluminescent element, V₂O₅Or Re₂O₇When forming the charge generation layer 6 with metal oxides such as Alq₃The efficiency of the electron transport layer in contact with the electrons injected from the charge generation layer 6 is extremely low. Therefore, the configuration of the interface on the anode 3 side of the charge generation layer 6 becomes an extremely important point.

Therefore, the object of the present invention is to laminate a stacked display element with light-emitting units composed of organic layers, using stable materials to improve environmental resistance, and to improve the charge generation layer sandwiched between the light-emitting units. For the charge injection efficiency of the light-emitting unit, a display device with high brightness and excellent long-term reliability is provided, and at the same time, it is easy to manufacture.

In order to achieve this objective, the first display element of the present invention is between the cathode and the anode, a plurality of light-emitting units containing at least an organic light-emitting layer are laminated, and a charge generation layer is sandwiched between the light-emitting units; it is characterized by: charge generation The layer is composed of an oxide containing at least one of an alkali metal and an alkaline earth metal.

In addition, the second display element of the present invention is formed between a cathode and an anode, a plurality of light-emitting units containing at least an organic light-emitting layer are laminated, and a charge generation layer is sandwiched between the light-emitting units; it is characterized in that: the charge generation layer The interface on the anode side is provided with an interface layer using a fluoride containing at least one of an alkali metal and an alkaline earth metal.

In addition, the third display element of the present invention is between the cathode and the anode, and a plurality of light-emitting units containing at least an organic light-emitting layer are laminated, and a charge generation layer is sandwiched between the light-emitting units; it is characterized in that the charge generation layer is The mixed layer of at least one element among alkali metals and alkaline earth metals and the organic material and the intrinsic charge generation layer are in contact with each other, and are laminated in order from the anode side.

As explained above, according to the display elements of the first and second inventions, since at least a part of the charge generating layer uses an oxide containing at least one of an alkali metal or an alkaline earth metal, and at least one of an alkali metal and an alkaline earth metal is used The fluoride and other materials will improve the charge injection efficiency of the light-emitting unit. As a result, in a stacked display element in which light-emitting units composed of organic layers are laminated, the lifetime characteristics caused by the increase in brightness and environmental resistance can be improved, and the long-term reliability can also be improved. In addition, the above-mentioned use of materials such as oxides containing at least one of alkali metals or alkaline earth metals, fluorides containing at least one of alkali metals and alkaline earth metals, etc., is in the form of oxides or fluorides from the film formation stage. State use, the use of such a charge generation layer is also stable. In addition, since a stable material is used to form such a charge generation layer with excellent charge injection characteristics, it can be easily manufactured without the need for film formation in consideration of the stoichiometric ratio.

Furthermore, if the display element according to the third invention uses a charge generation layer composed of an organic compound and a stable material such as alkali metals, alkaline earth metals, etc., the luminous efficiency of the stacked display element can be improved. As a result, similar to the first and second display elements, the stacked display elements in which light-emitting units composed of organic layers are laminated can achieve improved brightness and improved life characteristics due to improved environmental resistance, which can also achieve long-term Increased reliability. In addition, since a stable material is used to form such a charge generation layer with excellent charge injection characteristics, it can be easily manufactured without the need for film formation in consideration of the stoichiometric ratio.

Hereinafter, each embodiment of the display element of the present invention will be described in detail based on the drawings.

<First implementation type>

Fig. 1 is a cross-sectional view showing a configuration example of a display element of the first embodiment. The display element 10 shown in this figure is a stacked display element 10 formed by stacking light-emitting units. It includes: an anode 13 provided on the substrate 12; and a plurality of light-emitting units 14-1, 14 stacked on the anode 13 -2,...(here two); the charge generation layer 15-0 provided between the light-emitting units 14-1 and 14-2; and the cathode 16 provided on the uppermost light-emitting unit 14-2.

In the following description, the following description explains the structure of the display element of the upper light-emitting method, which is taken out from the cathode 16 side opposite to the substrate 12: the holes injected from the anode 13 and the charge generation layer 15- 0 When the electrons generated are combined in the light-emitting unit 14-1, and when the electrons injected from the cathode 16 and the holes generated in the charge generation layer 15-0 are combined in the light-emitting unit 14-2 The resulting luminescence.

First, the substrate 12 provided with the display element 10 is appropriately selected from transparent substrates such as glass or silicon substrates, and even flexible substrates in the form of thin films for use. In addition, when the driving method of the display device constituted by the display element 10 is the active matrix method, the substrate 12 is a TFT substrate formed by providing TFTs in each pixel. At this time, the display device has a structure in which the display element 10 of the upper light-emitting method is driven by TFT.

Moreover, in order to effectively inject holes, the anode 13 provided as the lower electrode on the substrate 12 can increase the work function of the electrode material from the vacuum level, such as chromium (Cr), gold (Au), and tin oxide. (SnO₂) Alloys with antimony (Sb), alloys of zinc oxide (ZnO) and aluminum (Al), and oxides of these metals or alloys, etc., are used alone or in a mixed state.

When the display element 10 adopts the upper light emitting mode, the anode 13 is made of high reflectivity material, which can utilize the interference effect and high reflectivity effect to improve the efficiency of light extraction to the outside. For this type of electrode material, it is advisable to use such as Al, Ag Etc. as the main component of the electrode. On these high-reflectivity material layers, for example, a transparent electrode material layer with a large work function, such as ITO, can also improve the charge injection efficiency.

Furthermore, when the driving method of the display device constituted by the display element 10 is the active matrix method, the anode 13 is patterned on each pixel provided with TFT. In addition, an insulating film with a pattern omitted here is provided on the upper layer of the anode 13 so that the opening of the insulating film exposes the surface of the anode 13 of the isotropic element.

In addition, the light-emitting units 14-1 and 14-2 are formed by sequentially stacking, for example, a hole injection layer 14 a, a hole transport layer 14 b, a light emitting layer 14 c, and an electron transport layer 14 d from the anode 13 side. These layers are composed of organic layers formed by other methods such as vacuum evaporation method or spin coating method. There are no restrictions on the material constituting each organic layer. For example, the hole transport layer 14b can use hole transport materials such as benzidine derivatives, dicinnamylamine derivatives, triphenylmethane derivatives, and hydrazone derivatives.

Of course, each layer 14a-14d has other requirements, which does not hinder this. For example, the light-emitting layer 14c may also be an electron-transporting light-emitting layer that also serves as the electron-transporting layer 14d, and the light-emitting layer 14c may also be a hole-transporting light-emitting layer 14c. Also, each layer may have a laminated structure. For example, the light-emitting layer 14c may be a white light-emitting element further formed by a blue light-emitting part, a green light-emitting part, and a red light-emitting part.

In addition, the light-emitting layer 14c may also be an organic thin film containing a small amount of organic substances such as pentadiene derivatives, coumarin derivatives, pyran-based pigments, triphenylmethane derivatives, etc. In this case, the material constituting the light-emitting layer 14c It is formed by co-evaporation of trace molecules.

In addition, each of the above organic layers, for example, the hole injection layer 14a and the hole transport layer 14b may be a laminated structure composed of a plurality of layers. The hole injection layer 14a is preferably made of non-aromatic amine-based organic materials such as acridine-based materials, so as to improve the hole injection efficiency for the light-emitting unit 14-2.

In addition, each of the above light-emitting units 14-1 and 14-2 may have completely the same structure, but may be made into other structures. For example, by forming the light-emitting unit 14-1 as an organic layer structure for an orange light-emitting element, and forming the light-emitting unit 14-2 as an organic layer structure for a blue-green light-emitting element, the light emission color becomes white.

Furthermore, the charge generation layer 15-0 provided between the light-emitting unit 14-1 and the light-emitting unit 14-2 is composed of an oxide containing at least one of an alkali metal and an alkaline earth metal. In addition, in the following, as the alkali metal system, Li, Na, K, Rb, Cs, and Fr are exemplified, and as the alkaline earth metal system, Be, Mg, Ca, Sr, Ba, and Ra are exemplified. And here, an oxide containing at least one of these elements is used to form the charge generation layer 15-0.

Here, as the oxide constituting the charge generation layer 15-0, in addition to general alkali metal oxides and alkaline earth metal oxides, composite oxides containing at least one of alkali metals and alkaline earth metals and other elements are also used. Things. Furthermore, as specific examples of oxides that form composite oxides with alkali metals or alkaline earth metals, there are boron oxides, tetraboron oxides, germanium oxides, manganese oxides, niobium oxides, silicon oxides, Tantalum oxide, titanium oxide, vanadium oxide, tungsten oxide, zirconium oxide, carbon oxide, pyrene oxide, chromite oxide, chromium oxide, dichromium oxide, ferrite, selenite oxide , Selenium oxide, tin oxide, tellurite oxide, tellurium oxide, bismuth oxide, tetraboron oxide, and boron oxide. Among them, Li should be used as the main component₂CO₃, Cs₂CO₃Or Li₂SiO₃, Hereinafter represented as Li₂CO₃。

The charge generation layer 15-0 can also be, for example: Li₂CO₃The single-layer structure composed.

Also, the charge generation layer 15-0 is made of Li₂CO₃As the main component, as the jumping side of holes or electrons (charges), for example, charge-transporting organic materials such as hole-transporting materials or electron-transporting materials, and Li₂CO₃A mixed layer formed by co-evaporation may also be used. In addition, it may be a layer having this mixed layer.

In addition, the charge generation layer 15-0 may also be Li₂CO₃And Li₂CO₃A laminated structure with a mixed layer of a charge-transporting organic material is also possible. At this time, Li₂CO₃The mixed layer with electron transporting organic material is laminated on Li₂CO₃The interface on the anode 13 side of the composed layer. Again, Li₂CO₃The mixed layer with the hole transporting organic material is laminated on Li₂CO₃The interface on the cathode 16 side of the composed layer. In this case, the hole transport material is preferably made of non-aromatic amine-based organic materials such as acridine-based materials. Furthermore, this type of laminated structure can also be used as a₂CO₃At least one of the anode 13 side and the cathode 16 side of the composed layer is provided with a mixed layer.

In addition, the charge generation layer 15-0 may also be Li₂CO₃The laminated structure of the layer composed of other oxides or composite oxides. In this case, other oxides or composite oxides can be exemplified: boron oxide, tetraboron oxide, germanium oxide, manganese oxide, niobium oxide, silicon oxide, tantalum oxide, titanium oxide, vanadium Oxide, tungsten oxide, zirconium oxide, carbon oxide, pyrite oxide, chromite oxide, chromium oxide, dichromium oxide, ferrite, selenite oxide, selenium oxide, tin oxide, Telluride oxide, tellurium oxide, bismuth oxide, tetraboron oxide, boron oxide and other general oxides or composite oxides.

Moreover, the charge generation layer 15-0 structured as above may be a structure in which fluoride is further laminated.

At this time, at the interface on the anode 13 side of the charge generation layer 15-0, as the middle cathode layer (intermediate cathode layer), it is advisable to install a fluoride containing at least one of alkali metals and alkaline earth metals (at least one element) Floor. Moreover, at the interface on the anode 13 side of the charge generation layer 15-0, as the intermediate anode layer, it is preferable to provide a layer containing at least one of alkali metals and alkaline earth metals via a conductive material layer.

Furthermore, as alkali metal fluorides and alkaline earth metal fluorides, specific examples include lithium fluoride (LiF), CsF, and CaF₂Wait. In addition, the conductive material layer contains at least one of magnesium (Mg), silver (Ag), and aluminum (Al). Specifically, a conductive material layer composed of MgAg or Al is exemplified.

In addition, the charge generation layer 15-0 can also be provided at the interface on the cathode 16 side with a layer composed of a hole-injecting material with a phthalocyanine skeleton, such as copper phthalocyanine (CuPc), as the anode layer in the middle (middle Anode layer).

Furthermore, each layer laminated on the above charge generation layer 15-0 or its interface is not necessarily limited to a clearly separated structure, and each constituent material may be mixed with each other at the interface of each layer.

Next, the cathode 16 is composed of a three-layer structure in which a first layer 16a, a second layer 16b, and a third layer 16c are stacked in this order from the anode 13 side.

The first layer 16a is made of a material with a small work function and good light transmittance. As this type of material, for example, lithium (Li) oxide Li can be used₂O or carbon oxide Li₂CO₃, Cesium (Cs) carbon oxide Cs₂CO₃, Silicon oxide Li₂SiO₃, And further mixtures of these oxides can be used. In addition, the first layer 16a is not limited to such materials. For example, alkaline earth metals such as calcium (Ca) and palladium (Ba), alkali metals such as lithium (Li) and cesium (Cs), and indium (In) may also be used. , Magnesium (Mg), Silver (Ag) and other metals with small work functions, and the fluorides and oxides of these metals are used alone or as a mixture or alloy of these metals, fluorides and oxides to improve stability Sexual use.

In addition, the second layer 16b is composed of an electrode containing MgAg or alkaline earth metal, or an electrode such as Al. As in the above light-emitting element, when the electrode 16 is composed of a semi-transmissive electrode, a thin-film MgAg electrode or a Ca electrode can be used to extract light. It is made of a material with light permeability and good conductivity. Especially when the display element 10 is an upper light-emitting element composed of a cavity structure that resonates light emission between the anode 13 and the cathode 16, for example: Mg-Ag Semi-transmissive reflective materials such as the like to form the second layer 16b. Thereby, the interface of the second layer 16b and the interface of the light-reflective anode 13 reflects light to obtain a cavity effect.

In addition, in order to suppress electrode deterioration, the third layer 16c is provided with a transparent lanthanide oxide, which can be formed as a sealing electrode capable of extracting light.

Furthermore, the above-mentioned first layer 16a, second layer 16b, and third layer 16c are formed by methods such as a vacuum evaporation method, a sputtering method, and a plasma CVD method. In addition, when the driving method of the display device composed of this display element is the active matrix method, the cathode 16 is formed by the insulating film covering the periphery of the anode 13 and the light-emitting unit 14-1 to the light-emitting unit 14 which are omitted here. The laminated film of -2 is insulated from the anode 13 and formed on the substrate 12 as a flat film, and may be used as a common electrode for each pixel.

In addition, the electrode structure of the cathode 16 shown here is a three-layer structure. However, as long as it is a laminated structure necessary for the separation of the functions of the various layers constituting the cathode 16, the cathode 16 may be composed of only the second layer 16b. Alternatively, a transparent electrode such as ITO may be further formed between the first layer 16a and the second layer 16b, of course, as long as the optimal combination and laminated structure are adopted for the fabricated device structure.

In the display element 10 of the above-described structure, the light-emitting unit 14-1 and 14-2 are sandwiched by Li of a stable material.₂CO₃The charge generation layer 15-0 as the main component will increase the electron injection efficiency from the charge generation layer 15-0 to the light-emitting unit 14-1 on the anode 13 side. Therefore, it is possible to stabilize the stacked display element 10 in which the light-emitting units 14-1 and 14-2 are laminated via the charge generation layer 15-0.

Furthermore, when a layer containing at least one of alkali metal and alkaline earth metal fluoride is provided at the interface on the anode 13 side of the charge generation layer 15-0 as the intermediate cathode layer, a conductive material layer such as MgAg is used And a layer composed of a fluoride containing at least one of an alkali metal and an alkaline earth metal arranged on the anode 13 side of the conductive material layer to form an intermediate cathode layer, which can improve the charge generation layer 15-0 to the charge The effect of the electron injection efficiency of the light-emitting unit 14-1 on the anode 13 side of the layer 15-0 is produced.

In addition, by providing an intermediate anode layer with a phthalocyanine skeleton on the charge generation layer 15-0 (illustration omitted), the light emission from the charge generation layer 15-0 to the cathode 16 side of the charge generation layer 15-0 can be improved. The effect of hole injection efficiency of unit 14-2.

As a result, in the stacked display device, not only the brightness is improved, but also the life characteristics caused by the improvement of environmental resistance can be improved, and the long-term reliability can also be improved. In addition, a stable material is used to form the charge generation layer 15-0 with excellent charge injection characteristics. Therefore, it can be easily manufactured without the need for film formation in consideration of the stoichiometric ratio. Moreover, compared to the use of V₂O₅The formed charge generation layer also has the effect of suppressing the driving voltage, thereby improving the long-term reliability.

<Second Implementation Type>

Fig. 2 is a cross-sectional view showing a configuration example of the display element of the second embodiment. The difference between the display element 11 shown in this figure and the display element 10 described using FIG. 1 lies in the structure of the charge generation layer 15, and the other structures are the same. Hereinafter, the configuration of the display element 11 of the second embodiment will be described in detail with the charge generation layer 15 as the center.

That is, in the display element 11 of the second embodiment, the charge generation layer 15 provided between the light-emitting unit 14-1 and the light-emitting unit 14-2 uses at least one (at least one) of alkali metals and alkaline earth metals. Element) composed of oxides. Furthermore, the charge generation layer 15 has a structure in which the interface layer 15a and the intrinsic charge generation layer 15b are sequentially stacked from the anode 13 side. Furthermore, this interface layer 15a functions as a cathode for the light-emitting unit 14-1 provided in contact with the anode 13. Therefore, in the following, this interface layer 15a is referred to as an intermediate cathode layer 15a. In addition, the intermediate cathode layer 15a is composed of an oxide containing at least one of an alkali metal and an alkaline earth metal.

In addition, the intrinsic charge generation layer 15b provided in contact with the intermediate cathode layer 15a uses the charge generation layer V described in JP 2003-45676 A and 2003-272860₂O₅It is constituted, or it is constituted by the organic compound shown below.

Here, as the oxide containing at least one of an alkali metal and an alkaline earth metal constituting the intermediate cathode layer 15a, the same oxide as described in the first embodiment is used.

Among them, the intermediate cathode layer 15a is preferably made of Li₂SiO₃Constituted.

Also, except for V₂O₅For example, the material constituting the intrinsic charge generation layer 15b can use an organic compound represented by the following general formula (1).

<chemistry general="n"><img file="TW200539733A_D0001.tif" /></chemistry>

In this general formula (1), R¹~R⁶Are independently selected from hydrogen, halogen, hydroxyl, amine, aromatic amine, aromatic oxy, substituted or unsubstituted carboxyl with a carbon number of less than 20, substituted or unsubstituted celerylic acid with a carbon number of less than 20 Ether, substituted or unsubstituted alkyl with 20 or less carbon, substituted or unsubstituted alkenyl with 20 or less carbon, substituted or unsubstituted alkoxy with 20 or less carbon, substituted or unsubstituted with 30 carbon or less Substituents for substituted aromatic groups, substituted or unsubstituted heterocyclic groups with 30 or less carbon atoms, nitrile groups, nitro groups, cyano groups or silyl groups. Again, R¹~R⁶Middle, adjacent R^m(m=1~6) It can also be combined with each other via a ring structure. Moreover, X in general formula (1)¹~X⁶Each is independently a carbon or nitrogen atom.

As a specific example of the organic compound represented by such general formula (1), the organic compound of structural formula (1)-1 to structural formula (1)-64 shown in the following Table 1 to Table 7 is shown. Furthermore, in these structural formulas, [Me] represents methyl (CH₃), [Et] represents ethyl [C₂H₅], [Pr] represents propyl (C₃H₇), [Ph] represents a phenol group (C₆H₅). Also, in structural formula (1)-61 to structural formula (1)-64, R in general formula (1)¹~R⁶Middle, adjacent R^m(m=1~6) is an example of organic compounds that are bonded to each other via a ring structure.

<tables><img file="TW200539733A_D0002.tif" /></tables>

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<tables><img file="TW200539733A_D0004.tif" /></tables>

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Moreover, the above-mentioned intermediate cathode layer 15a and intrinsic charge generation layer 15b are not necessarily limited to clearly separated structures, and the intermediate cathode layer 15a contains the material constituting the intrinsic charge generation layer 15b, or vice versa.

Furthermore, the charge generation layer 15 may be a structure in which an intermediate anode layer (illustration omitted) is sequentially stacked from the anode 13 side, together with the intermediate cathode layer 15a and the intrinsic charge generation layer 15b. The intermediate anode layer is composed of an organic material having a phthalocyanine skeleton, specifically, an intermediate anode layer composed of copper phthalocyanine (CuPc) is exemplified.

In addition, when the intrinsic charge generation layer 15b in the charge generation layer 15 is made of an organic compound represented by the above general formula (1), the intrinsic charge generation layer 15b can also serve as the hole injection layer 14a. At this time, it is not necessary to provide the hole injection layer 14a for the light emitting unit 14-2 provided on the side closer to the cathode 16 than the charge generation layer 15 is.

In the display element 11 of the second embodiment of the configuration described above, the charge generation layer 15 uses an oxide containing at least one of an alkali metal or an alkaline earth metal as the material constituting the intermediate cathode layer 15a to increase the charge The electron injection efficiency of the layer 15 to the light-emitting unit 14-1 on the anode 13 side is generated. Furthermore, especially the above-mentioned oxide constituting the intermediate cathode layer 15a of the charge generation layer 15 is supplied as a stable material from the film formation stage, so the use of the intermediate cathode layer 15a, that is, the stability of the charge generation layer 15 can be achieved. change.

In addition, by providing an intermediate anode layer with a phthalocyanine skeleton (illustration omitted) at the interface on the cathode 16 side of the charge generation layer 15, it is possible to improve the difference from the charge generation layer 15 to the cathode 16 side of the charge generation layer 15 The hole injection efficiency of the light-emitting unit 14-2.

As a result of the above, in the stacked display element 11, not only the brightness is improved, but also the life characteristics caused by the improvement of environmental resistance can be improved, and the long-term reliability can also be improved. In addition, stable materials are used to form the charge generation layer 15 with excellent charge injection characteristics. Therefore, it is not necessary to perform film formation in consideration of the stoichiometric ratio during its production, and such stacks with excellent long-term reliability can be easily produced. Type display element 11.

Moreover, even when the organic compound of the general formula (1) is used as the intrinsic charge generation layer 15b of the charge generation layer 15, the V₂O₅When the same degree of charge injection efficiency. At this time, since the intrinsic charge generation layer 15b can also serve as a hole injection layer, it is not necessary to arrange the light emitting unit 14-2 on the side of the cathode 16 than the charge generation layer 15, and the hole injection layer 14a may be provided in particular. Simplification of layer structure.

&lt;Third Implementation Type&gt;

Fig. 3 is a cross-sectional view showing a configuration example of the display element of the third embodiment. The difference between the display element 11' shown in this figure and the display element 10 illustrated in FIG. 1 lies in the structure of the charge generation layer 15', and the other structures are the same. Hereinafter, the structure of the display element 11' of the third embodiment will be described in detail with the charge generation layer 15' as the center.

That is, the charge generation layer 15' of the display element 11' of the third embodiment is formed by sequentially stacking the interface layer 15a' and the intrinsic charge generation layer 15b from the anode 13 side. Also, as in the second embodiment, this interface layer 15a' functions as a cathode for the light-emitting unit 14-1 provided in contact with the anode 13. Therefore, in the following, this interface layer 15a' is referred to as an intermediate cathode Layer 15a'.

The charge generation layer 15' constructed here is characterized in that the intermediate cathode layer 15a' is made of a fluoride containing at least one of an alkali metal and an alkaline earth metal (at least one element). In particular, the intermediate cathode layer 15a' is preferably a fluoride layer 15a-1 composed of a fluoride containing at least one of an alkali metal and an alkaline earth metal, and a conductive material layer 15a-2 or Laminated structure of insulating material layers (15a-2').

Furthermore, as the fluoride containing at least one of an alkali metal and an alkaline earth metal constituting the fluoride layer 15a-1, specific examples include lithium fluoride (LiF), cesium fluoride (CsF), and calcium fluoride (CaF).₂)。

In addition, as a material constituting the conductive material layer 15a-2, at least one of magnesium (Mg), silver (Ag), and aluminum (Al) is contained. Specifically, the conductive material layer 15a-2 composed of MgAg or Al is exemplified.

In addition, as the insulating material layer (15a-2'), a layer composed of an oxide containing at least one of an alkali metal and an alkaline earth metal (at least one element) can be preferably used. As such an oxide containing at least one of an alkali metal and an alkaline earth metal, the same oxide as described in the previous first embodiment is used.

In addition, the intrinsic charge generation layer 15b provided in contact with the intermediate cathode layer 15a' uses the charge generation layer V described in Japanese Patent Laid-Open Nos. 2003-45676 and 2003-272860₂O₅It is constituted, or is constituted by the organic compound represented by the above general formula (1). Moreover, when the intrinsic charge generation layer 15b in the charge generation layer 15' is made of an organic compound represented by the above general formula (1), the intrinsic charge generation layer 15b can also serve as the hole injection layer 14a. At this time, it is not necessary to provide the hole injection layer 14a for the light-emitting unit 14-2 provided on the side closer to the cathode 16 than the charge generation layer 15'. In addition, the charge generation layer 15' is located closer to the cathode 16 than the intrinsic charge generation layer 15b, and an intermediate anode layer composed of organic materials with a phthalocyanine skeleton such as copper phthalocyanine (CuPc), which is omitted here, is laminated. The above system is the same as the second embodiment.

In the display element 11' of the third embodiment of such a configuration, the charge generation layer 15' is improved by using an oxide containing at least one of an alkali metal or an alkaline earth metal as the material constituting the intermediate cathode layer 15a' The electron injection efficiency from the charge generation layer 15' to the light-emitting unit 14-1 on the anode 13 side. In particular, the material containing the oxide of at least one of an alkali metal and an alkaline earth metal, which constitutes the intermediate cathode layer 15a' of the charge generating layer 15', is supplied as a stable material from the film formation stage. Therefore, the intermediate cathode layer 15a', that is, the stabilization of the charge generation layer 15 can be sought.

Furthermore, the intermediate cathode layer 15a' is a fluoride layer 15a-1 composed of a fluoride containing at least one of an alkali metal and an alkaline earth metal, and a conductive material layer 15a- such as MgAg, which are sequentially laminated from the anode 13 side. At 2 o'clock, the electron injection efficiency for the light-emitting unit 14-1 arranged on the anode 13 side than the intermediate cathode layer 15a' can be further improved.

In addition, since the charge generation layer 15' is closer to the cathode 16 side than the intrinsic charge generation layer 15b, an intermediate anode layer (illustration omitted) composed of an organic material with a phthalocyanine skeleton is provided, thereby improving the separation from the charge generation layer 15' The hole injection efficiency of the light-emitting unit 14-2 where the charge generation layer 15 is arranged on the cathode 16 side.

As a result of the above, if the display element 11' according to the third embodiment is the same as the first embodiment, the stacked display element 11' of the light-emitting unit 14-1 and 14-2 composed of laminated organic layers, The long-term reliability can be improved, and such a stacked display element 11' with excellent long-term reliability can be easily manufactured.

Moreover, even when the organic compound of the above general formula (1) is used as the intrinsic charge generation layer 15b of the charge generation layer 15', the V₂O₅At the same time, the charge injection efficiency is the same as that of the second embodiment, so that the simplification of the layer structure can also be achieved.

&lt;Fourth Implementation Type&gt;

FIG. 4 is a cross-sectional view showing a configuration example of the display element of the fourth embodiment. The difference between the display element 11" shown in this figure and the display element 10 illustrated in FIG. 1 lies in the structure of the charge generation layer 15", and the other structures are the same. Hereinafter, the configuration of the display element 11" of the fourth embodiment will be described in detail with the charge generation layer 15" as the center.

That is, the charge generation layer 15" of the display element 11" of the fourth embodiment is a structure in which a mixed layer 15a" and an intrinsic charge generation layer 15b are sequentially stacked from the anode 13 side. Moreover, this mixed layer 15a" Since the light-emitting unit 14-1 provided in contact with the anode 13 functions as a cathode, in the following, this mixed layer 15a" is referred to as an intermediate cathode layer 15a".

The charge generation layer 15" constructed here is characterized in that the intermediate cathode layer (mixed layer) 15a" is composed of a mixture of materials containing at least one element of alkali metals and alkaline earth metals and organic materials. Specific examples of alkali metals and alkaline earth metals include lithium (Li), cesium (Cs), sodium (Na), potassium (K), rubidium (Rb), calcium (Ca), strontium (Sr), barium (Ba ). In addition, as the organic material constituting the intermediate cathode layer (mixed layer) 15a", it is suitable to use, for example, Alq₃Or ADN and other organic materials with electron transport properties.

In addition, the intrinsic charge generation layer 15b is provided in contact with the intermediate cathode layer (mixed layer) 15a", and is composed of an organic compound represented by the above general formula (1).

Furthermore, although the drawings are omitted here, the intermediate cathode layer 15a" is a fluoride layer composed of fluorides containing at least one (at least one element) of an alkali metal and an alkaline earth metal layered in order from the anode 13 side. And the structure of the above-mentioned mixed layer.

Furthermore, in the fourth embodiment, since the intrinsic charge generation layer 15b is made of the organic compound represented by the above general formula (1), the intrinsic charge generation layer 15b can also serve as the hole injection layer 14a. Therefore, it is not necessary to provide the hole injection layer 14a for the light-emitting unit 14-2 located on the side closer to the cathode 16 than the charge generation layer 15". Moreover, the charge generation layer 15" is located closer to the cathode than the intrinsic charge generation layer 15b. On the 16 side, an intermediate anode layer composed of organic materials with a phthalocyanine skeleton such as copper phthalocyanine (CuPc), which is omitted here, is laminated. The above system is the same as the second embodiment.

In the display element 11" of the fourth embodiment of such a configuration, the mixed layer 15a" of at least one element among alkali metals and alkaline earth metals and an organic material is combined with the organic material shown in the above general formula (1). The intrinsic charge generation layer 15b composed of the compound is in contact with each other, and the charge generation layer 15" sequentially stacked from the anode 13 side is sandwiched between the light-emitting units 14a-1 and 14a-2. It is confirmed that the layer emits light. The stacked display element of the unit will obtain light with sufficient luminous efficiency. Moreover, since the above-mentioned materials constituting the charge generation layer 15" are all stable materials, the stability of the charge generation layer using this can be achieved.

From the above results, if the fourth embodiment is the same as the display elements of the second embodiment and the third embodiment, it is possible to achieve a stacked type in which light-emitting units 14-1 and 14-2 composed of organic layers are stacked. The long-term reliability of the display element 11" is improved, and such a stacked display element 11" with excellent long-term reliability can be easily manufactured. In addition, as the intrinsic charge generation layer 15b, by using the organic compound represented by the above general formula (1), the layer structure can be simplified.

Furthermore, the display elements of the present invention described in the above embodiments are not limited to display elements used in active matrix display devices using TFT substrates, but can also be applied as display elements in passive display devices. The same effect (improved long-term reliability).

In addition, in each of the above embodiments, a case where light is extracted from the side of the cathode 16 provided on the side opposite to the substrate 12 is described in the case of the "upper light emitting type". However, if the substrate 12 is made of a transparent material, the present invention can also be applied to a "transmissive" display element that emits light from the substrate 12 side. At this time, using the laminated structure illustrated in FIGS. 2 to 4, a transparent electrode material with a large work function, such as ITO, is used to form the anode 13 on the substrate 12 composed of the transparent material. Thereby, light emission is taken out from both the side of the substrate 12 and the side opposite to the substrate 12. In addition, in such a configuration, the cathode 16 is formed of a reflective material so that only the light emitted from the side of the substrate 12 can be taken out. At this time, a sealing electrode such as AuGe, Au, Pt, etc. may be added to the uppermost side of the cathode 16.

Moreover, even if the laminated structure described in FIGS. 1 to 4 is used, the transparent material is stacked on the opposite side of the substrate 12, and the anode 13 is used as the upper electrode. It can also be configured to take out the light from the substrate 12 side. The "through-type" display element. In this case, the anode 13 of the upper electrode is changed to a transparent electrode in order to extract light from both the side of the substrate 12 and the side opposite to the substrate 12.

&lt;Other implementation types&gt;

The display elements of the first to fourth embodiments described above can also be combined with the color conversion film. Hereinafter, the display element of FIG. 1 described in the first embodiment is cited to illustrate the structure of the display element using the color conversion film. The display elements of the second to fourth embodiments can be similarly applied.

First, in FIG. 5, the display element (10) described in the first embodiment is shown as the display element 10a of the "top-emission type" that emits light from the substrate 12 and the opposite side. At this time, the constructed display element 10a is provided with a color conversion layer 18 above the cathode 16 on the light-emitting side. Here, when the light-emitting layer 14c of the display element 10a is an excitation light source of blue wavelength, the color conversion layer 18 is arranged: corresponding to each pixel portion, the excitation light source of blue wavelength is converted into a color conversion film 18a of red wavelength, And the blue wavelength excitation light source is converted into a green color conversion film 18b. In addition, the color conversion layer 18 except for the color conversion film 18a and the color conversion film 18b is provided with a material film through which the excitation light source of the blue wavelength does not undergo wavelength conversion. The display element 10a constructed here can perform full-color display.

Furthermore, the color conversion layer 18 with the color conversion films 18a, 18b of such a structure can be formed by the photolithography technology of the conventional technology.

FIG. 6 shows another display element 10b when the display element (10) described in the first embodiment is of the "upper light emitting type". As shown in this figure, on the upper portion of the cathode 16 from the light-emitting side, the color conversion layers 18 and 19 may also be laminated. At this time, corresponding to each pixel portion, the color conversion films 18a, 19a that convert the excitation light source of blue wavelength into red wavelength, and the color conversion films 18b, 19b that convert the excitation light source of blue wavelength into green are laminated and arranged. The color conversion films 18a, 19a and the color conversion films 18b, 19b of these stacked configurations are stacked so as to be a combination that is converted into a desired wavelength by the light of both sides. In addition, a color conversion film 19c may be provided to further convert the excitation light source of blue wavelength into blue with good chromaticity. Moreover, in the color conversion layer 19 part other than the color conversion films 19a to 19c, a material film is provided that does not convert the wavelength of the excitation light source of the blue wavelength and allows it to pass. Even with the display element 10b constructed in this way, full-color display can still be performed.

FIG. 7 shows a display element 10c when the display element (10) described in the first embodiment is a "transmissive type" that emits light from the side of the substrate 12. At this time, between the anode 13 on the light-emitting side and the substrate 12, the display element 10c provided with the color conversion layer 18 is constructed. The composition of the color conversion layer 18 is the same as described above. Even with the display element 10c constructed in this way, full-color display can still be performed.

FIG. 8 shows another display element 10d when the display element (10) described in the first embodiment is a "transmissive type". As shown in this figure, the color conversion layers 18 and 19 may also be stacked between the anode 13 on the light-emitting side and the substrate 12. The composition of the color conversion layers 18 and 19 is the same as described above. Even with the display element 10d constructed as above, full-color display can still be performed.

In the configuration of the display elements 10a to 10d described above using FIGS. 5 to 8, the charge generation layer 15-0 is changed to the charge generation layer 15, 15' of the configuration described in each of the above-mentioned embodiments 2 to 4 , 15" to form display elements 11a, 11a', 11a"... corresponding to each implementation type.

Example

Next, specific examples of the present invention and the manufacturing steps of the display elements of the comparative examples of these examples will be described, as well as the evaluation results of these. Furthermore, in the following &lt;Examples 1 to 4&gt;, referring to Table 8, the production of each display element 10 of the first embodiment shown in FIG. 1 will be described. In the following &lt;Examples 5-20&gt;, referring to Table 9, the production of each display element 11 of the second embodiment shown in FIG. 2 will be described. In addition, in &lt;Examples 21 to 24&gt;, referring to Table 10, the production of each display element 11' of the third embodiment shown in FIG. 3 will be described. In addition, in &lt;Examples 25 to 36&gt;, refer to Table 11 to describe the production of each display element 11" of the fourth embodiment shown in FIG. 4. Also, in &lt;Examples 37 to 58&gt;, refer to Table 12~ Table 14 illustrates the production of the display element 10a with the configuration shown in Fig. 5. Furthermore, after the description of each embodiment, the production and evaluation results of the comparative example will be described.

&lt;Examples 1~4&gt;

In each of Examples 1 to 4, in the configuration of the display element 10 of the first embodiment illustrated in FIG. 1, each display element 10 in which the charge generation layer 15-0 is made of various materials and a laminated structure was fabricated. Hereinafter, first, the manufacturing steps of the display element 10 of Examples 1 to 4 will be described.

On a substrate 12 composed of a 30 mm×30 mm glass substrate, ITO (with a film thickness of about 120 nm) is formed as the anode 13, and SiO₂Evaporate to produce a cell for organic electroluminescent elements with an insulating film (illustration omitted) that covers the area outside the light-emitting area of 2 mm×2 mm.

Secondly, as the hole injection layer 14a constituting the first layer of the light-emitting unit 14-1, a film thickness of 15 nm (evaporation rate 0.2~0.4 nm/sec) is used to form acridine The structure formula (1)-10 of the hole injection material of benzene organic material.

Next, as the hole transport layer 14b, by a vacuum evaporation method, with a film thickness of 15 nm (evaporation speed 0.2~0.4 nm/sec), the following structural formula (2) α-NPD (double [N- (1-Naphthyl ester)-N-phenolic]benzidine).

<chemistry general="n"><img file="TW200539733A_D0009.tif" /></chemistry>

In addition, as the light-emitting layer 14c, ADN represented by the following structural formula (3) is used as the main component, BD-052x (Idemitsu Kosan Co., Ltd.; trade name) is used as the dopant, and the vacuum vapor deposition method is used to make The film thickness ratio becomes 5%, and these materials are formed into a film with a total film thickness of 32 nm.

<chemistry general="n"><img file="TW200539733A_D0010.tif" /></chemistry>

Finally, as the transport layer 14d, the Alq shown in the following structural formula (4)₃[Three (8-quinoline oxyhydroxide) aluminum (III)], the film is formed by a vacuum evaporation method with a film thickness of 18 nm.

<chemistry general="n"><img file="TW200539733A_D0011.tif" /></chemistry>

After forming the first layer of the light-emitting unit 14-1 as described above, the charge generation layer 15-0 was vapor-deposited with each film thickness of the material shown in Table 8 below.

<tables><img file="TW200539733A_D0012.tif" /></tables>

Here, in Example 1, 15<img file="TW200539733A_D0013.tif" />The film thickness will be Li₂SiO₃A film is formed to form a single-layer structure charge generation layer 15-0. Furthermore, in Examples 2 and 3, Li₂SiO₃And the hole injection material LGCHIL001 are co-evaporated to form a single-layered charge generation layer 15-0 composed of a mixed layer with respective film thicknesses. Furthermore, the composition ratio is Li₂SiO₃: LGCHIL001=4:1 (film thickness ratio). Moreover, in Example 4, in Li₂SiO₃On the first layer composed of Li₂SiO₃: LGCHIL001=4:1 (film thickness ratio) The second layer of laminated charge generation layer 15-0 composed of mixed layers.

After the above, the light-emitting unit 14-2 of the second layer is formed in the same manner as the light-emitting unit 14-1 of the first layer.

Next, as the first layer 16a of the cathode 16, LiF was formed with a film thickness of about 0.3 nm by a vacuum evaporation method (evaporation rate 0.01 nm/sec or less), and secondly, as the second layer 16b, a vacuum evaporation method was used. In the plating method, MgAg is formed with a film thickness of about 10 nm, and finally as the third layer 16c, Al is formed with a film thickness of 300 nm.

&lt;Comparative Examples 1~4&gt;

Using the configuration of the display element described in FIG. 1, a display element having the configuration shown in Table 8 above was produced with the configuration of the charge generation layer 15-0. The manufacturing step is the same as the manufacturing step of the above-mentioned embodiment, and only the step of changing the formation process of the charge generation layer 15-0. In addition, in the formation process of the charge generation layer 15-0 of each of Comparative Examples 1 to 4, Li was first formed₂SiO₃Composed film thickness 15<img file="TW200539733A_D0014.tif" />The first layer, the upper part of this form V₂O₅The second layer of each film thickness.

&lt;Comparative Example 5&gt;

In the configuration of the display element illustrated in FIG. 1, the light-emitting unit 14-1 is provided on the anode 13, and the light-emitting unit 14-2 is directly stacked without interposing the charge generation layer 15-0, and the cathode 16 is fabricated on the upper part. The display components. The manufacturing steps are the same as those in the above embodiments, and only the steps of forming the charge generation layer 15-0 are omitted.

&lt;Comparative Example 6&gt;

Using the configuration of the display element illustrated in FIG. 1, the light-emitting unit 14-1 is provided on the anode 13, and a single-unit display element with the cathode 16 directly provided on the light-emitting unit 14-1 is fabricated. The manufacturing steps are the same as those in the above-mentioned embodiment, and only the anode 13, the light-emitting unit 14-1, and the cathode 16a are formed in the same steps.

Evaluation result-1

In Table 8 above, the luminous efficiency (Quantum Yield (quantum efficiency): Q/Y) of the display devices of Examples 1 to 4 and Comparative Examples 1 to 6 produced as described above are also shown. This result shows that compared with the single cell structure of Comparative Example 6, the luminous efficiency of any of the display elements of Examples 1 to 4 is improved, and the effect of forming the stacked-type charge generation layer 15-0 of the present invention can be confirmed.

In addition, in Comparative Examples 1 to 4, approximately the same effects as those of Examples 1 to 4 can be obtained, but compared to Examples 1 to 4, the driving voltage becomes higher and the IV characteristic shifts to the higher voltage side. This is implied in the past use of generally adopted V₂O₅As this comparative example of the charge generation layer, there is generated power consumption in the charge generation layer 15-0. Therefore, confirm that V is not used₂O₅, By using Li₂SiO₃Using the charge generation layer 15-0 as the main component will have the effect of lowering the driving voltage.

Furthermore, in Comparative Example 5 in which the light-emitting units 14-1 and 14-2 are laminated without interposing a charge-generating layer, the luminous efficiency is substantially the same as that of Comparative Example 6, showing the necessity of the charge-generating layer 15-0.

In addition, in the above Examples 1 to 4, a particularly unstable material is not used, and a film with a strict composition on the stoichiometric ratio is formed, and each display element can be easily manufactured using only stable materials.

&lt;Examples 5~16&gt;

In each of Examples 5 to 16, in the configuration of the display element 11 of the second embodiment illustrated in FIG. 2, each display element 11 in which the charge generation layer 15 is made of various materials and laminated structures is produced. Hereinafter, first, the manufacturing steps of the display element 11 of Examples 5 to 16 will be described.

On a substrate 12 composed of a 30 mm×30 mm glass plate, ITO (with a film thickness of about 120 nm) is formed as the anode 13, and SiO₂Evaporate to produce a cell for organic electroluminescent elements with an insulating film (illustration omitted) that covers the area outside the light-emitting area of 2 mm×2 mm.

Secondly, as the hole injection layer 14a constituting the first layer of the light-emitting unit 14-1, a film thickness of 15 nm (evaporation speed 0.2~0.4 nm/sec) was formed by vacuum evaporation to form Idemitsu Kosan Co., Ltd. The hole injection material HI-406 manufactured by the company.

Next, as the hole transport layer 14b, the α-NPD (double [ N-(1-naphthyl ester)-N-phenolic]benzidine).

In addition, as the light-emitting layer 14c, the ADN shown in the above structural formula (3) is used as the main component, and BD-052x (Idemitsu Kosan Co., Ltd.; trade name) is used as the dopant. The thickness ratio becomes 5%, and these materials are formed into a film with a total thickness of 32 nm.

Finally, as the transport layer 14d, the Alq shown in the above structural formula (4)₃[Three (8-quinoline oxyhydroxide) aluminum (III)], the film is formed by a vacuum evaporation method with a film thickness of 18 nm.

After forming the first layer of the light-emitting unit 14-1 as described above, the charge generation layer 15 was vapor-deposited with each film thickness of the material shown in Table 9 below.

<tables><img file="TW200539733A_D0015.tif" /></tables>

Here, in Examples 5-16, firstly serve as the intermediate cathode layer 15a of the charge generation layer 15, and 15<img file="TW200539733A_D0016.tif" />The film thickness of each material shown in Table 9 above was formed into a film.

Next, in Examples 5-14, as the intrinsic charge generation layer 15b, 120<img file="TW200539733A_D0017.tif" />The film thickness will be V₂O₅Evaporation. On the other hand, in Examples 15 and 16, as the intrinsic charge generation layer 15b, the organic compound shown in the structural formula (1)-10 in Table 1 above was used as 120<img file="TW200539733A_D0018.tif" />The film thickness is formed into a film.

Moreover, only in Example 14, it was further used as an intermediate anode layer (not shown), and 20<img file="TW200539733A_D0019.tif" />The thickness of the film will be copper phthalocyanine (CuPc) vapor deposition.

After the above, the light-emitting unit 14-2 of the second layer is formed in the same manner as the light-emitting unit 14-1 of the first layer.

Next, as the first layer 16a of the cathode 16, LiF was formed with a film thickness of about 0.3 nm by a vacuum evaporation method (evaporation rate 0.01 nm/sec or less), and secondly, as the second layer 16b, a vacuum evaporation method was used. In the plating method, MgAg is formed with a film thickness of about 10 nm, and finally as the third layer 16c, Al is formed with a film thickness of 300 nm. Thereby, a transmissive display element 11 from which light is taken out from the side of the substrate 12 is obtained.

&lt;Examples 17, 18&gt;

In Examples 17 and 18, instead of the structure of Example 15, as HI-406 of the hole injection layer 14a of the first layer of light-emitting unit 14-1, the structural formula (1)-10 in Table 1 is shown as The organic compound is formed with a film thickness of 15 nm. Furthermore, without forming the hole injection layer 14a of the second-layer light-emitting unit 14-2, a display element with a structure that is combined with the intrinsic charge generation layer 15b composed of the structural formula (1)-10 in Table 1 was fabricated. Among them, the structure of the charge generation layer 15 has the respective film thicknesses shown in Table 9.

&lt;Examples 19 and 20&gt;

In Examples 19 and 20, in the structure of the display element 11 of the first embodiment described using FIG. Here, in the production steps of Examples 5-16, the anode 13 is used as the anode 13 instead of ITO to form a silver alloy (the film thickness is about 100 nm), and the third layer 16c as the cathode 16 is replaced by Al to form 200 nm of IZO. (Indium zinc composite oxide). Furthermore, as shown in Table 9 above, in Example 19, the charge generating layers 15 were formed in the same manner as in Example 5, and in Example 20, the charge generating layers 15 were formed in the same manner as in Example 13.

&lt;Examples 21-22&gt;

In Examples 21 and 22, in the configuration of the display element 11' of the third embodiment described using FIG. 3, the charge generation layer 15' is made of a separate material and each display element 11' of a laminated structure. In these Examples 21 and 22, in the production steps of the above-mentioned Examples 5-16, except that the structure of the charge generation layer 15' was changed to the structure shown in Table 10 below, the same as those of Examples 5-16 were adopted. In the step, a transmissive display element 11' is fabricated. That is, in Examples 21 and 22, the charge generation layer 15' has a three-layer structure, and a conductive material layer composed of a MgAg (composition ratio 10:1) film is laminated on the fluoride layer 15a-1 composed of LiF 15a-2, and stacked by V₂O₅The intrinsic charge generation layer 15b is composed. The film thickness of each layer is shown in Table 10.

<tables><img file="TW200539733A_D0020.tif" /></tables>

&lt;Examples 23, 24&gt;

In Examples 23 and 24, in the configuration of the display element 11' of the third embodiment described using FIG. Here, in the production steps of the above-mentioned Examples 21 and 22, the anode 13 is used as the anode 13 instead of ITO to form a silver alloy (the film thickness is about 100 nm), and the third layer 16c as the cathode 16 is replaced by Al to form 200 nm of IZO. (Indium zinc composite oxide). Furthermore, as shown in Table 10 above, in Example 23, each charge generation layer 15' was formed in the same manner as Example 21, and in Example 24, each charge generation layer 15' was formed in the same manner as Example 22.

&lt;Comparative Example 7&gt;

Using the configuration of the display element described in FIG. 3, a single-unit display element in which the light-emitting unit 14-1 is provided on the anode 13 and the cathode 16 is directly provided on the light-emitting unit 14-1 is produced. The manufacturing steps are the same as those in the foregoing Examples 5-16, and only the anode 13, the light-emitting unit 14-1, and the cathode 16 are formed in the same steps.

&lt;Comparative Example 8&gt;

In the configuration of the display element illustrated in FIG. 3, the light-emitting unit 14-1 is provided on the anode 13, and the light-emitting unit 14-2 is directly stacked without interposing the charge generation layer 15', and a cathode 16 is formed on the top Display components. The manufacturing steps are the same as those in the above-mentioned Embodiments 5-16, and only the steps of forming the charge generation layer 15 are omitted.

&lt;Comparative Examples 9-11&gt;

Using the configuration of the display element described in FIG. 3, the charge generation layer 15' can be fabricated to have a display element having the configuration shown in Table 10 above. The production steps are the same as the production steps of the above-mentioned Examples 5-16. Among them, in Comparative Example 9, when the charge generation layer 15' is formed, only the intrinsic charge generation layer 15b is changed to 120<img file="TW200539733A_D0021.tif" />The film thickness of V₂O₅Evaporation. Moreover, in Comparative Examples 10 and 11, when the charge generation layer 15' was formed, LiF was formed with a respective film thickness as the intermediate cathode layer 15a', followed by the intrinsic charge generation layer 15b with a thickness of 120<img file="TW200539733A_D0022.tif" />The film thickness of evaporation V₂O₅。

&lt;Comparative Example 12&gt;

The structure of the single-cell type display element produced in Comparative Example 7 was produced on the top surface emitting type display element that emits light from the side opposite to the substrate 12. Here, in the manufacturing steps of the display element described in Comparative Example 7, Ag alloy (film thickness of about 100 nm) is formed as the anode 13 and the third layer 16c as the cathode 16 is formed with 200 nm IZO (indium zinc composite). Oxide), other than that, a display element was produced in the same steps as in Comparative Example 7.

Evaluation result-2

Fig. 9 shows the luminous efficiency of the display elements of Example 5 and Example 14, and Comparative Examples 7 to 11 produced as described above. As shown in this graph, the luminous efficiency of the display elements of Examples 5 and 14 is doubled compared to the luminous efficiency of the single unit type light-emitting element of Comparative Example 7. In addition, in other Examples 6-13, 15-24, even if the transmission type, top-emission type, especially the organic compound of the structural formula (1)-10 in Examples 15 and 16 are used to omit part of the hole injection The constitution of the layer 14a has doubled the luminous efficiency of the luminous efficiency of the light-emitting element of the single unit type of Comparative Example 7. Thereby, the effect of forming the stacked-type charge generating layers 15 and 15' of the present invention can be confirmed.

In particular, Example 14 in which the charge generation layer 15 has an intermediate anode layer (CuPc) at the interface on the cathode 16 side, compared with other examples, confirmed that the luminous efficiency was further improved. Thereby, by providing such an intermediate anode layer, it is confirmed that the hole injection efficiency for the light-emitting unit 14-2 arranged on the side closer to the cathode 16 than the charge generation layer 15 is improved.

Furthermore, with regard to the display element with the structure of directly laminating the light-emitting unit of Comparative Example 8, the light-emitting efficiency cannot be higher than that of the single unit type of Comparative Example 7, which shows the necessity of the charge generation layer 15 (15'). To use the V of Comparative Example 9₂O₅The display element composed of a single-layer charge generation layer cannot effectively inject electrons and holes from the charge generation layer into the electron transport layer 14d and the hole injection layer 14a, respectively, and cannot obtain approximately the same luminous efficiency as that of Comparative Example 1.

In Comparative Examples 10 and 11, even if the fluoride layer (LiF) 15a-1 is directly laminated on the intrinsic charge generation layer (V₂O₅) 15b, it is still unable to perform good electron injection, which means that as in Examples 21 and 22, the conductive material layer (MgAg, etc.) 15a-2 can be effectively injected.

Furthermore, from the results of Comparative Example 11, if the driving voltage is increased, the interface of the charge generation layer 15 is destroyed and the efficiency rises rapidly. This also implies that the fluoride layer (LiF) 15a-1 is directly laminated on the intrinsic charge generation layer 15 Layer (V₂O₅) The composition of 15b does not effectively perform charge injection. Confirm the effect caused by the conductive material layer (MgAg, etc.) 15a-2 placed in between.

In addition, in the above Examples 5-24, a particularly unstable material is not used, and a film with a strict composition on the stoichiometric ratio is formed, and each display element can be easily manufactured using only stable materials.

Evaluation result-3

Fig. 10 shows the display elements of Example 19 and Comparative Example 12 produced as above, and the initial brightness is set to 3000 cd/m²And the result of life measurement. From this result, it can be confirmed that even with the above light-emitting device structure, the half-life of the stacked display device manufactured in Example 19 is greatly improved compared to the single-cell display device of Comparative Example 12, which is effective for improving long-term reliability. .

Evaluation result-4

Fig. 11 shows the display elements of Example 15 and Comparative Example 7 produced as above, and the initial brightness is set to 1500 cd/m², Duty (load) is 50, and the result of life measurement at room temperature. From this result, it can be confirmed that even in the display element using the organic compound represented by structural formula (1)-10 to form the intrinsic charge generation layer 15b, compared with the single unit type display element of Comparative Example 7, the display element is as described in Example 15. The half-life of the fabricated stacked display device is improved by more than 2 times, which is effective for the improvement of long-term reliability. The reason is that based on the acceleration constant for each element, the acceleration constant is generally expressed as 1 or more. Therefore, if the efficiency is improved by a factor of two, the life expectancy can be expected to be improved by a factor of more than two. This result is also obtained in this way.

&lt;Example 25~36&gt;

In Examples 25 to 36, in the configuration of the display element 11" of the fourth embodiment illustrated in FIG. 4, the charge generation layer 15" is made of a separate material and each display element 11" of a laminated structure. In these Examples 25 to 36, in the production steps of the above Examples 5 to 16, except that the structure of the charge generation layer 15" was changed to the structure shown in Table 11 below, the same as in Examples 5 to 16 was adopted. Step, fabricate a transmissive display element 11".

<tables><img file="TW200539733A_D0023.tif" /></tables>

That is, in Examples 25 to 36, as the intermediate cathode layer 15a" of the charge generation layer 15", the mixed layer of each alkali metal or alkaline earth metal and organic material (ADN or Alq) as shown in Table 11 above was used. The composition of the intermediate cathode layer 15a". Among them, in Examples 27, 28, 35, and 36, as the intermediate cathode layer 15a", the fluoride layer and the mixed layer were formed from the anode 13 side in order with respective film thicknesses. The laminated structure. And the organic material shown in the structural formula (1)-10 of Table 1 is used to form the intrinsic charge generation layer 15b connected with the intermediate cathode layer 15a".

&lt;Comparative Example 13&gt;

In Comparative Example 13, as in Comparative Example 7, a single unit type display element in which only the anode 13, the light-emitting unit 14-1, and the cathode 16 were formed was produced. Among them, the cathode 16 has the same structure as the charge generation layer 15" of Example 27. That is, the cathode 16 has the same structure as the first layer 16a/the second layer 16b/the third layer 16c=LiF (about 0.3 nm)/Alq₃+Mg(5%)(5 nm)/Al(20 nm). Thereby, a transmissive display element 11" from which light is taken out from the side of the substrate 12 is obtained.

&lt;Comparative Example 14&gt;

In Comparative Example 14, in the structure of Comparative Example 13, the cathode 16 was the same structure as the charge generation layer 15" of Example 28. That is, the structure of the cathode 16 was the first layer 16a/the second layer 16b/the first layer 16a/the second layer 16b. Three-layer 16c = LiF (about 0.3 nm)/Alq₃+Ca(5%)(5 nm)/Al(20 nm). Thereby, a transmissive display element 11" from which light is taken out from the side of the substrate 12 is obtained.

Evaluation result-5

Fig. 12 shows the display elements of Example 27 and Comparative Example 13 produced as above, and the current density is set to 125 mA/cm²When the duty (load) is 50, the result of the life characteristics measured at room temperature. Furthermore, at this time, the initial brightness of Example 27 was about twice that of Comparative Example 13. Moreover, as shown in FIG. 12, the half-life of the initial brightness of the display element of Example 27 is equal to or more than the half-life of the initial brightness of the display element of Comparative Example 13. Therefore, compared to Comparative Example 13, the half-life of Example 27 The composition obtains more than 2 times the efficiency improvement effect. Therefore, it is confirmed to improve the life and efficiency of the display element with the stacked structure of the charge generation layer 15" as in Example 27, in which the charge generation layer 15" is stacked from the anode 13 side in order of alkali metals and alkaline earth metals. At least one (Mg) and organic material (Alq₃), and an intrinsic charge generation layer 15b composed of organic compounds represented by structural formula (1)-10.

Regarding the above, the comparison between Example 28 and Comparative Example 14 is also the same. Among them, the efficiency of the display element of Example 28 is maintained at about 1.3 times that of the display element of Comparative Example 14. However, under the same conditions as above (the current density is set to 125 mA/cm²When comparing the lifetime with Duty50, measured at room temperature, the half-life is almost the same in Comparative Example 14 and Example 28, and the long-life effect due to the laminated structure was confirmed.

Regarding the comparison of Examples 25 and 26 with Examples 27 and 28, compared with the display elements of Examples 25 and 26 in which the intermediate cathode layer 15a" has a single-layer structure, the display element has a LiF (conductive material layer) inserted on the interface side. In the display elements of Examples 27 and 28 of the intermediate cathode layer 15a" of the laminated structure, the improvement of the luminous efficiency and the effect of prolonging the life can be confirmed. However, this gap is small, and on the contrary, the improvement in efficiency and the longer life span caused by the stacked structure of the stacked light-emitting units have been reconfirmed.

Regarding the comparison of Examples 25, 29, and 30, the display elements of Examples 25, 29, and 30 differ in the addition amount of at least one of the alkali metal and alkaline earth metal (Mg) added to the intermediate cathode layer 15a" The luminous efficiency can be approximately the same value as in Example 25, but as the Mg ratio increases, the deviation in life measurement becomes larger. From a statistical point of view, compared with the life improvement effect of Example 25, take Example 29, In the order of 30, the effect tends to become smaller. It is predicted that this factor is due to the change in the film quality from the intermediate cathode layer 15a" as the Mg ratio increases. According to the review of the inventors, the ratio of alkali metals and alkaline earth metals is 50% (relative film thickness ratio) as the upper limit of Example 30. Increasing the ratio above this will result in a decrease in transmittance and a decrease in the intermediate cathode layer 15a". The increased instability of the film quality may be disadvantageous in forming the stacked structure of the stacked light-emitting unit.

Regarding the comparison of Examples 31 to 34, in these display elements, for the intermediate cathode layer (mixed layer) 15" that constitutes the charge generation layer 15", Li and Cs of alkali metals are used, and for the organic materials that are co-evaporated , Use Alq₃And ADN. Moreover, in all the display elements of Examples 31 to 34, approximately twice the luminous efficiency of Comparative Example 13 was obtained, and the life-span improvement effect was approximately the same as that of FIG. 11.

Regarding the comparison of Examples 35 and 36, these display elements have the same tendency as the comparison of Examples 27 and 28 and Examples 25 and 26, compared to inserting LiF (conductive material layer) in the middle cathode layer 15a". On the contrary, the stacked structure of the stacked light-emitting unit has reconfirmed the efficiency improvement and long life span caused by the stacked structure of the stacked light-emitting unit.

&lt;Example 37~58&gt;

In Examples 37 to 58, the transmissive display elements 11c, 11c', and 11c" illustrated in FIG. 7 were produced. In the production of these Examples 37 to 58, firstly, the glass plate of 30 mm×30 mm On the composition substrate 12, the color conversion layer 18 is formed by the photolithography technology of the conventional technology. The color conversion layer 18 converts the excitation light source of the blue wavelength into the color conversion film 18a of the red wavelength, and the blue wavelength The excitation light source is converted into a green wavelength color conversion film 18b for patterning.

Thereafter, on the top of the color conversion layer 18, according to the manufacturing steps of the above-mentioned embodiments 5-16, the anode 13-16 is formed. Among them, as the hole injection layer 14a of the light-emitting units 14-1 and 14-2, the 2-TNATA shown in the following structural formula (5) is formed at 15 nm (evaporation speed 0.2~0.4 nm/sec) [4, 4', 4"-Tris(2-naphtholaniline) triphenylamine]. In addition, the charge generation layers 15, 15', 15" were changed to the configurations shown in Tables 12 to 14 below.

<chemistry general="n"><img file="TW200539733A_D0024.tif" /></chemistry>

<tables><img file="TW200539733A_D0025.tif" /></tables>

<tables><img file="TW200539733A_D0026.tif" /></tables>

<tables><img file="TW200539733A_D0027.tif" /></tables>

&lt;Comparative Example 15&gt;

Illustrated in FIG. 7 of the constituent elements of the display, 18, 13 arranged thereto on the anode substrate 12 in the light emitting unit 14-1 and the anode 13 is provided a color conversion layer on the light emitting unit 14-1 made thereto disposed directly opposite cathode 16 single unit display element. The manufacturing steps are the same as those in Examples 37 to 58, only the color conversion layer 18, the anode 13, the light-emitting unit 14-1, and the cathode 16 are formed in the same steps.

Evaluation result-6

FIG. 13 shows the luminous efficiency of the display elements of Example 50 and Comparative Example 15 produced as described above. As shown in this graph, the luminous efficiency of the display element of Example 50 is twice that of the luminous efficiency of the single unit type light-emitting element of Comparative Example 15. In addition, in other Examples 45 to 58, the luminous efficiency of the light-emitting element of the single unit type of Comparative Example 15 was doubled. Thereby, even in the case of using the color conversion layer 18, the effect of forming the stacked-type charge generation layer 15-15" of the present invention can be confirmed.

&lt;Example 59&gt;

In Example 59, each display element 11c" of the upper light-emitting type illustrated in FIG. 5 was fabricated. Here, in the fabrication steps of the above-mentioned Example 50, chromium (Cr: film thickness of about 100) was formed as the anode 13 instead of ITO. nm), and as the third layer 16c of the cathode 16, IZO (Indium Zinc Composite Oxide) is formed at 200 nm instead of Al, and the light is taken out from the cathode 16. In addition, the color conversion layer 18 is formed on the cathode 16. .

&lt;Comparative Example 16&gt;

A single cell type display element corresponding to Example 59 was fabricated.

Evaluation result-7

Fig. 14 shows the display elements of Example 59 and Comparative Example 16 produced as above, and the initial brightness is set to 3000 cd/m²And the result of life measurement. From this result, it can be confirmed that even with the above light-emitting device structure, compared to the single-cell display device of Comparative Example 16, the half-life of the stacked display device manufactured in Example 59 is greatly improved, which is effective for improving long-term reliability. .

<p>1,1',10,10a~10d,11,11',11"...Display element</p><p>2,12. . . Substrate</p><p>3,13. . . anode</p><p>4. . . Organic layer</p><p>4-1,4-2,...; 14-1,14-2,...; 14a-1,14a-2. . . Light-emitting unit</p><p>4a, 14a. . . Hole injection layer</p><p>4b, 14b. . . Hole transport layer</p><p>4c, 14c. . . Luminescent layer</p><p>5,16. . . cathode</p><p>6,15,15-0,15',15"... charge generation layer</p><p>7. . . Electron injection layer</p><p>14d. . . Electron transport layer</p><p>15a, 15a'. . . Interface layer</p><p>15a"...mixed layer</p><p>15a, 15a', 15a"... Intermediate cathode layer</p><p>15a-1. . . Fluoride layer</p><p>15a-2. . . Conductive material layer</p><p>15a-2'. . . Insulating material layer</p><p>15b. . . Intrinsic charge generation layer</p><p>16a. . . level one</p><p>16b. . . Second floor</p><p>16c. . . the third floor</p><p>18,19. . . Color conversion layer</p><p>18a, 18b, 19a, 19b, 19c. . . Color conversion film</p>

Fig. 1 is a cross-sectional view showing a configuration example of a display element of the first embodiment.

Fig. 2 is a cross-sectional view showing a configuration example of the display element of the second embodiment.

Fig. 3 is a cross-sectional view showing a configuration example of the display element of the third embodiment.

FIG. 4 is a cross-sectional view showing a configuration example of the display element of the fourth embodiment.

FIG. 5 is a cross-sectional view showing the first example of the display element and the color conversion film of the combined implementation type.

FIG. 6 is a cross-sectional view showing a second example of the display element and the color conversion film of the combined implementation type.

FIG. 7 is a cross-sectional view showing a third example of the display element and the color conversion film of the combined implementation type.

FIG. 8 is a cross-sectional view showing a fourth example of the display element and the color conversion film of the combined implementation type.

9 is a graph showing the luminous efficiency of the display elements of Examples 5 and 14 and Comparative Examples 7-11.

10 is a graph showing the time-dependent changes in the relative brightness of the display elements of Example 19 and Comparative Example 12.

FIG. 11 is a graph showing the change over time of the relative brightness of the display elements of Example 15 and Comparative Example 7. FIG.

12 is a graph showing the time-dependent changes in the relative brightness of the display elements of Example 27 and Comparative Example 13.

FIG. 13 is a graph showing the luminous efficiency of the display elements of Example 50 and Comparative Example 15. FIG.

FIG. 14 is a graph showing the time-dependent changes in the relative brightness of the display elements of Example 59 and Comparative Example 16. FIG.

Fig. 15 is a cross-sectional view showing a conventional display device.

Fig. 16 is a cross-sectional view showing another structure of a conventional display device.