JP2008103396A - Light-emitting apparatus, manufacturing method of light-emitting apparatus, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting apparatus which simultaneously satisfies the following three items such as good carrier injection capability, the optimum carrier balance, and stability of carrier injection, without changing materials and configurations of anode and cathode sides. <P>SOLUTION: The light-emitting apparatus EL1 is provided with a functional layer 7 consisting of one or more layers including a light-emitting layer 4, and a pair of electrodes 3, 8 for sandwiching the functional layer 7. In the apparatus EL1, an organic solvent (organic solvent layer S) is disposed on an interface between two adjacent layers or an interface between the layer and the electrode adjacent each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device, a method for manufacturing the light emitting device, and an electronic apparatus.

  In recent years, organic EL devices using organic EL elements, which are self-luminous elements, as pixels have been developed. Organic EL devices are capable of high-speed response with high brightness and low power consumption, and are considered to be multicolored easily due to the variety of organic compounds. Research and development is in progress.

An organic EL element has a structure in which at least one organic thin film including a light emitting layer is sandwiched between a pair of upper and lower electrodes. When a voltage is applied to the organic EL element, holes are injected from the anode side and electrons are injected from the cathode side into the light emitting layer, and the two recombine to cause a light emission phenomenon. In general, since organic materials have a wide band gap, it is very difficult to inject carriers as compared with inorganic semiconductors. However, in Non-Patent Document 1, by using an anode and cathode configuration with high carrier injection properties. It has succeeded in injecting carriers into the light emitting layer at a low voltage to emit light. Since then, in order to drive the organic EL element at a lower voltage, materials and configurations on the anode side and the cathode side that easily inject carriers into the light emitting layer have been vigorously developed.
CWTang and SAVanslyke, Appl.Phys.Lett. 51 (1987) 913.

  On the other hand, in order to drive the organic EL element with high efficiency, it is important to inject holes and electrons in a balanced manner. This is because the proportion of carriers that cannot be recombined increases when the balance between injected holes and electrons is poor. Therefore, in the development of an organic EL element, care must be taken so that the balance between injected holes and electrons is not lost while improving the carrier injection property. From the above, it can be said that a technique for controlling the amount of carriers injected into the light emitting layer is indispensable for driving the organic EL element with low voltage and high efficiency.

  However, at present, in order to adjust the amount of carriers injected into the light emitting layer, the materials and configurations on the anode and cathode sides must be changed, and the materials and configurations having optimum injection properties are searched one by one. Development is one of the major burdens of developing organic EL elements. Further, even if a material and a structure having a desired injection property are obtained, it is not preferable that the material lacks stability, such as a decrease in the injection amount accompanying the deterioration of the material. That is, since it is required to develop a material and a structure that can satisfy the three requirements of good carrier injection, optimum carrier balance, and stability of carrier injection, it is very difficult to develop an organic EL element. In view of the above background, there has been a demand for the development of a new technology that can easily control the carrier injection amount.

  The present invention has been made in view of such circumstances, and without changing the material and configuration on the anode side and the cathode side, good carrier injection property, optimum carrier balance, carrier injection stability 3 It is an object of the present invention to provide a light emitting device and a method for manufacturing the same capable of satisfying the above. It is another object of the present invention to provide an electronic device with high reliability and display quality by including such a light emitting device.

  In order to solve the above problems, a light-emitting device of the present invention includes a functional layer including one or two or more layers including a light-emitting layer, and a pair of electrodes that sandwich the functional layer. An organic solvent is disposed at an interface between the two layers or at an interface between the layers adjacent to each other and the electrode. According to this configuration, the amount of carriers injected between the two adjacent layers or between the adjacent layers and the electrode can be easily controlled by the material and film thickness of the organic solvent. As a result, a high carrier injection property and an optimum carrier balance are realized at the same time, and the light emitting element can be driven with low voltage and high efficiency. In addition, by inserting an organic solvent between layers or between layers and electrodes, deterioration due to a chemical reaction at these interfaces is suppressed, so the carrier injection amount is less likely to decrease. A light emitting element can be realized. Furthermore, since the carrier injection amount can be controlled without changing the material and configuration of the layers and electrodes, it is necessary to search for a new material and configuration having a desired injection property and injection stability as in the past. There is no. As a result, the development cost can be reduced, and a light-emitting device equipped with a high-quality light-emitting element can be provided at a low price.

  In the present invention, the organic solvent is disposed only at the interface between the two adjacent layers or between the layer and the electrode adjacent to each other, and is not disposed inside the layer or the electrode. Is desirable. According to this configuration, the organic solvent can be prevented from becoming a carrier trap site in the layer or the electrode, and the light emitting element can be driven with low voltage and high efficiency.

  In the present invention, the organic solvent is preferably an organic solvent that does not dissolve the layer or the electrode. According to this configuration, it is possible to prevent a decrease in injection efficiency due to the layer or electrode being dissolved by the organic solvent.

  In the present invention, the organic solvent is preferably a polar solvent. According to this configuration, since the organic solvent is polarized by the voltage applied to the light emitting element, the carrier injection barrier between the layers or between the layers and the electrodes is relaxed, and quantum mechanical carrier injection (tunneling) is performed. Carrier injection due to the effect) increases. Therefore, when a sufficient carrier injection amount is not obtained, the carrier injection amount can be increased and the carrier balance can be adjusted.

  In the present invention, the relative permittivity of the organic solvent is desirably 10 or more. According to this configuration, since a large voltage is applied to the organic solvent, the energy band of the organic solvent can be greatly distorted. As a result, the carrier injection barrier between layers or between layers and electrodes is greatly relaxed, and quantum mechanical carrier injection can be dramatically increased. For example, when considering carrier injection at the interface between the light emitting layer and the cathode, the relative permittivity of the light emitting layer is about 2 to 3, so that when the relative permittivity of the organic solvent is 10 or more, it is applied to the light emitting element. Most of the voltage is applied to the organic solvent. In this case, the energy band of the organic solvent is greatly distorted by polarization, and the LUMO level of the light emitting layer is moved in a direction that matches the energy level of the cathode. As a result, electrons supplied from the cathode are easily injected into the light emitting layer by the tunnel effect, and the amount of carrier injection increases dramatically (about 2 to 3 times).

  In the present invention, it is preferable that the organic solvent is disposed with a thickness of one molecular layer to several molecular layers at an interface between two adjacent layers or an interface between the adjacent layers and the electrode. According to this configuration, quantum mechanical carrier injection can be dramatically increased.

  In the present invention, the organic solvent is preferably a nonpolar solvent. According to this configuration, no current flows through the portion where the organic solvent is disposed. Therefore, when the carrier injection amount is excessive, the carrier injection amount can be decreased and the carrier balance can be adjusted.

  A method for manufacturing a light emitting device according to the present invention is a method for manufacturing a light emitting device comprising a functional layer including one or more layers including a light emitting layer, and a pair of electrodes sandwiching the functional layer, The surface of the layer or the electrode is exposed to an atmosphere filled with an organic solvent, and the other layer or the other electrode is formed in a state where molecules of the organic solvent are interposed on the surface of the layer or the electrode. It is characterized by that. According to this method, the amount of carriers injected between the two adjacent layers or between the adjacent layers and the electrode can be easily controlled by the material and film thickness of the organic solvent. As a result, a high carrier injection property and an optimum carrier balance are realized at the same time, and the light emitting element can be driven with low voltage and high efficiency. Also, by inserting an organic solvent between layers or between layers and electrodes, deterioration due to chemical reaction at these interfaces is suppressed, so the carrier injection amount is unlikely to decrease, and long life A light-emitting element can be realized. Furthermore, since the carrier injection amount can be controlled without changing the material and configuration of the layers and electrodes, it is necessary to search for a new material and configuration having a desired injection property and injection stability as in the past. There is no. As a result, the development cost can be reduced, and a light-emitting device equipped with a high-quality light-emitting element can be provided at a low price.

  In the present invention, the other layer or the other electrode is preferably formed by a dry process. According to this method, since the organic solvent adhering to the surface of the underlying layer or electrode is not washed away, the organic solvent can be reliably disposed between the layers or between the layers and the electrodes. it can.

  In the present invention, the layer or the electrode is preferably formed by a dry process. According to this method, when the organic solvent is attached, the layer or the electrode can be prevented from being dissolved by the organic solvent.

  In the present invention, the amount of the organic solvent attached to the surface of the layer or the electrode is preferably controlled by the time during which the surface of the layer or the electrode is exposed to the atmosphere filled with the organic solvent. According to this method, the amount of the organic solvent adhering to the surface of the layer or electrode can be accurately controlled. For example, if the concentration of the organic solvent is too high, the surface of the layer or electrode may be condensed with the organic solvent and dissolved depending on the material of the layer or electrode. When the amount of the solvent is appropriately controlled, such a problem does not occur, and a high-quality light-emitting device can be provided.

  In the present invention, when the surface of the layer or the electrode is exposed to the atmosphere filled with the organic solvent, the temperature of the surface of the layer or the electrode, the temperature of the atmosphere, and the temperature of the organic solvent are constant, respectively. It is desirable to control the temperature. According to this method, the amount of the organic solvent adhering to the surface of the layer or electrode can be accurately controlled.

  An electronic apparatus according to the present invention includes the light emitting device of the present invention described above or the light emitting device manufactured by the method of manufacturing the light emitting device of the present invention described above. According to this configuration, an electronic device with high reliability and excellent display quality can be provided.

  The present invention will be described below with reference to the drawings. In all the drawings below, the film thicknesses and dimensional ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of an organic EL device EL1 which is the first embodiment of the light emitting device of the present invention. The organic EL device EL1 has a substrate body 2 made of glass, quartz, plastic or the like as a base, and an anode 3 as a first electrode, a light emitting layer 4, an organic solvent layer S, and a second electrode on the substrate body 2. A cathode 8 is provided. The light emitting layer 5 and the organic solvent layer S are formed of an organic material, and the functional layer 7 is formed of the light emitting layer 5 and the organic solvent layer S. The functional layer 7 is sandwiched between the first electrode 3 and the second electrode 8, and the organic EL element 9, which is a light emitting element, is formed by the first electrode 3, the functional layer 7, and the second electrode 8. ing.

  A wiring for applying a drive voltage is connected to the first electrode 3 and the second electrode 8. Holes from the first electrode 3 and electrons from the second electrode 8 are injected into the light emitting layer 4 through the wiring. The holes and electrons injected into the light emitting layer 4 move in the light emitting layer 5 and recombine. The energy released during the recombination generates excitons, and when the excitons return to the ground state, energy is emitted in the form of fluorescence or phosphorescence. The light emitted from the organic EL element 9 is emitted from the substrate body 2 made of a glass substrate or the like and extracted outside (bottom emission method). When the second electrode 8 is formed of a transparent conductive film such as ITO, light emitted from the organic EL element 9 can be extracted from the second electrode 8 side (top emission method). In the following description, electrons and holes injected into the light emitting layer 4 may be referred to as carriers.

  Here, the light emitting layer 5 includes a known light emitting material capable of emitting fluorescence or phosphorescence. Specifically, (poly) fluorene derivative (PF), (poly) paraphenylene vinylene derivative (PPV), polyphenylene derivative (PP), polyparaphenylene derivative (PPP), polyvinyl carbazole (PVK), polythiophene derivative, polymethyl Polysilanes such as phenylsilane (PMPS) are preferably used. In addition, these polymer materials include polymer materials such as perylene dyes, coumarin dyes, rhodamine dyes, rubrene, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, Nile red, coumarin 6, and quinacridone. It can also be used by doping a low molecular weight material such as. Alternatively, a low molecular material such as carbazole (CBP) can be doped with these low molecular dyes to form a light emitting layer. Tris-8-quinolinolato aluminum complex (Alq3) can also be added as an electron transporting layer as part of the light emitting layer.

  The organic solvent layer S includes an organic solvent having a thickness of one molecular layer to several molecular layers at the interface between the light emitting layer 4 and the second electrode 8. The organic solvent is not particularly limited as long as it does not deteriorate the light emitting layer 4 and the second electrode 8, and may be one generally used for manufacturing an organic EL element, such as benzene, xylene, and toluene. In FIG. 1, the organic solvent layer S is described as a continuous layer, but the organic solvent constituting the organic solvent layer S is arranged in an island shape (sparsely) at the interface between the light emitting layer 4 and the second electrode 8. It does not necessarily have to be formed as a continuous layer.

  Next, the operation of the organic solvent layer S will be described with reference to FIG. In the same figure, (a) is explanatory drawing at the time of using a nonpolar solvent as an organic solvent, (b) is explanatory drawing at the time of using a polar solvent as an organic solvent. As shown in FIG. 2A, since an organic solvent generally has insulating properties, when the organic solvent Sm is present between the light emitting layer 4 and the second electrode 8, a current is present in the portion where the organic solvent Sm is present. It stops flowing. By utilizing this property, for example, when carrier injection from the second electrode 8 is excessive, carrier balance can be adjusted by reducing the amount of injected carriers.

  On the other hand, as shown in FIG. 2B, when sufficient carrier injection is not obtained from the second electrode 8, for example, a highly polar solvent such as methanol and acetone (relative dielectric constant is 10 or more). May be selected and disposed on the surface of the light emitting layer 4. Although the organic solvent has an insulating property, in the case of a highly polar solvent, the organic solvent is polarized by the applied voltage, so that the carrier injection barrier from the second electrode 8 to the light emitting layer 4 is relaxed, and the quantum mechanics due to the tunnel effect. This is because the typical carrier injection increases dramatically.

  FIG. 3 is a diagram showing a band diagram of the organic EL element 9 when a polar solvent is used. In the figure, (a) shows a state before voltage application, and (b) shows a state after voltage application. As shown in FIG. 3A, in the state before applying a voltage to the electrode, a large carrier barrier is formed between the second electrode 8 and the light emitting layer 4, which is larger than this carrier barrier. Only carriers having energy are injected into the light emitting layer 4. However, since the organic solvent layer S, which is an insulating film, is formed between the second electrode 8 and the light emitting layer 4, only carriers that have passed through the organic solvent layer S due to the tunnel effect contribute to light emission.

  On the other hand, as shown in FIG. 3B, when a voltage is applied to the electrode, the band of the organic solvent layer S is greatly distorted, and the LUMO (lowest unoccupied molecular orbital) level of the light emitting layer 4 is the energy of the second electrode 8. Move in the direction that matches the level. As a result, carriers supplied from the second electrode 8 are easily injected into the light emitting layer 4 due to the tunnel effect, and the amount of carriers injected into the light emitting layer 4 increases dramatically. In the case of a polar solvent, since the relative dielectric constant is sufficiently larger than that of the light emitting layer, the applied voltage is concentrated on the organic solvent layer S, and only the band of the organic solvent layer 8 changes greatly. For example, if the relative permittivity of the polar solvent is 10 or more, the relative permittivity of the light emitting layer is usually about 2 to 3, so that the voltage applied between the electrodes is generally applied only to the organic solvent layer S. . As a result, the LUMO level of the light emitting layer 4 is greatly lowered, and the light emitting layer 4 can be moved to a level that substantially matches the energy level of the second electrode 8.

  Next, a manufacturing method of the organic EL device EL1 will be described with reference to FIG. First, as shown in FIG. 4A, the light emitting layer 4 is formed on the substrate 2 on which the first electrode 3 is formed. As a method for forming the light emitting layer 4, a vacuum vapor deposition method can be used in the case of a low molecular light emitting material, and a spin coating method or an ink jet method can be used in the case of a polymer light emitting material, but is not particularly limited in the present invention. . In addition, it is a well-known technique until the above process.

  Next, as shown in FIG. 4B, the substrate 2 is exposed to an atmosphere filled with an organic solvent, and the organic solvent is attached to the surface of the light emitting layer 4. An atmosphere filled with an organic solvent can be formed by placing a container 52 containing an organic solvent 53 inside a container 50 having high chemical resistance such as stainless steel. The organic solvent 53 to be attached is not particularly limited as long as it does not deteriorate the light emitting layer 4 and the second electrode 8, and may be one generally used for manufacturing an organic EL element, such as benzene, xylene, and toluene.

  The amount of the organic solvent 53 attached to the surface of the light emitting layer 4 can be controlled by the time during which the light emitting layer 4 is exposed to the organic solvent atmosphere. In that case, it is desirable to control the temperature of the surface of the light emitting layer 4, the temperature of the atmosphere, and the temperature of the organic solvent 53 to be constant. In addition, when the concentration of the organic solvent 53 in the atmosphere is too high, the surface of the light emitting layer 4 is condensed by the organic solvent and may be dissolved depending on the material of the light emitting layer 4, so care must be taken. For example, in the case of attaching xylene, the temperature of the surface of the light emitting layer 4, the temperature of the atmosphere, and the temperature of the organic solvent 53 are all uniformly set to 30 ° C. An organic solvent layer S having a thickness of several molecular layers is obtained.

  In FIG. 4B, the heating device 51 that heats the substrate 2 is described as a temperature control unit that controls the temperature of the surface of the light emitting layer, but in addition to the heating device 51, the temperature of the container 52 of the organic solvent 53 is also illustrated. A temperature control means for controlling the temperature and a temperature control means for controlling the temperature inside the container 50 are provided as necessary.

  When the organic solvent layer S is formed on the surface of the light emitting layer 4, the second electrode 8 is formed on the light emitting layer 4 and the organic solvent layer S. A method for forming the second electrode 8 may be a vacuum deposition method or the like, but is not particularly limited in the present invention. However, in the case where the second electrode 8 is formed by a dry process such as a vacuum deposition method, the organic material attached to the surface of the light emitting layer 4 serving as a base is compared with a case where a wet process such as an inkjet method or a spin coating method is used. The solvent is not washed away. Therefore, an organic solvent can be reliably disposed between the light emitting layer 4 and the second electrode 8, which is preferable.

  If the 2nd electrode 8 is formed on the light emitting layer 4 and the organic solvent layer S, a sealing member will be arrange | positioned on the surface of the 2nd electrode 8 and the light emitting layer 4 as needed, and a sealing process will be performed. Thus, the organic EL element 9 is completed.

  As described above, in the organic EL device EL1 of the present embodiment, since the organic solvent layer S is disposed at the interface between the light emitting layer 4 and the second electrode 8, the light emitting layer 4 and the second electrode 8 are The amount of carriers injected between them can be easily controlled by the material and film thickness of the organic solvent. As a result, high carrier injection property and optimum carrier balance are realized at the same time, and the organic EL element 9 can be driven with low voltage and high efficiency. In addition, by inserting an organic solvent between the light emitting layer 4 and the second electrode 8, deterioration due to a chemical reaction at these interfaces is suppressed, so that a long-life organic EL that hardly reduces the amount of injected carriers. Element 9 can be realized. Furthermore, since the carrier injection amount can be controlled without changing the material and configuration of the light emitting layer 4 and the second electrode 8, a novel material having a desired injection property and injection stability as in the past and There is no need to explore the configuration. As a result, the development cost can be reduced, and the organic EL device EL1 equipped with the high-quality organic EL element 9 can be provided at a low price.

  Further, since the organic solvent is disposed only on the surface of the light emitting layer 4 by exposing the light emitting layer 4 to an atmosphere filled with the organic solvent, carrier injection at the interface between the light emitting layer 4 and the second electrode 8 is performed. It can be involved only in sex. That is, since the organic solvent is disposed only at the interface between the light emitting layer 4 and the second electrode 8 and is not disposed within the light emitting layer 4 or the second electrode 8, the organic solvent is disposed inside the light emitting layer 4 or the second electrode 8. It can be prevented from becoming a carrier trap site, and the organic EL element 9 can be driven with low voltage and high efficiency.

  In addition, although this embodiment demonstrated the case where the light emitting layer 4 was formed with an organic light emitting material, the light emitting layer 4 can also be formed not only with an organic light emitting material but with an inorganic light emitting material. In this case, the obtained light emitting element is an inorganic EL element. In the case of an inorganic EL element, the light emitting layer 4 is also performed by a dry process such as a vacuum deposition method. In this case, when the organic solvent layer S is formed, the light emitting layer 4 can be prevented from being dissolved by the organic solvent.

[Second Embodiment]
FIG. 5 is a schematic configuration diagram of an organic EL device EL2 which is a second embodiment of the light emitting device of the present invention. In addition, the same code | symbol is attached | subjected about the same component as 1st Embodiment, and detailed description is abbreviate | omitted.

  The organic EL device EL2 has a substrate body 2 made of glass, quartz, plastic, or the like as a base, and an anode 3 as a first electrode, a first organic solvent layer S1, a hole injection layer 5, a first electrode on the substrate body 2. Two organic solvent layers S2, a light emitting layer 4, a third organic solvent layer S3, an electron injection layer 6, a fourth organic solvent layer S4, and a cathode 8 as a second electrode are provided. The first organic solvent layer S1, the hole injection layer 5, the second organic solvent layer S2, the light emitting layer 4, the third organic solvent layer S3, the electron injection layer 6 and the fourth organic solvent layer S4 are formed of an organic material. The functional layer 7 is formed by the first organic solvent layer S1, the hole injection layer 5, the second organic solvent layer S2, the light emitting layer 4, the third organic solvent layer S3, the electron injection layer 6 and the fourth organic solvent layer S4. Has been. The functional layer 7 is sandwiched between the first electrode 3 and the second electrode 8, and the organic EL element 9, which is a light emitting element, is formed by the first electrode 3, the functional layer 7, and the second electrode 8. ing.

  Here, as the hole injection layer 5, an arylamine derivative, a phthalocyanine derivative, a polyaniline derivative + an organic acid, a polythiophene derivative + a polymer acid, or the like is used. In particular, a mixture (PEDOT / PSS) of polyethylene dioxythiophene and polystyrene sulfonic acid is suitable. Further, as the electron injection layer 6, a polyfluorene derivative, a polyparaphenylene vinylene derivative, a polyparaphenylene derivative, a polyvinyl carbazole, a polythiophene derivative, a polysilane-based polymer organic material such as polymethylphenylsilane is preferably used.

  The first organic solvent layer S <b> 1 includes an organic solvent having a thickness of one molecular layer to several molecular layers at the interface between the first electrode 3 and the hole injection layer 5. The organic solvent is not particularly limited as long as it does not deteriorate the first electrode 3 and the hole injection layer 5, and may be generally used for manufacturing an organic EL element. As the organic solvent material, a nonpolar solvent is used when the amount of carriers injected from the first electrode 3 to the hole injection layer 5 is excessive, and carrier injection from the first electrode 3 to the hole injection layer 5 is performed. If the amount is insufficient, a polar solvent is used. In FIG. 5, the first organic solvent layer S <b> 1 is described as a continuous layer, but the organic solvent constituting the first organic solvent layer S <b> 1 has an island shape at the interface between the first electrode 3 and the hole injection layer 5. (Sparsely) may be arranged, and does not necessarily have to be formed as a continuous layer.

  The second organic solvent layer S <b> 2 includes an organic solvent having a thickness of one molecular layer to several molecular layers at the interface between the hole injection layer 5 and the light emitting layer 4. The organic solvent is not particularly limited as long as it does not degrade the hole injection layer 5 and the light emitting layer 4, and may be generally used for manufacturing an organic EL element. As the organic solvent material, a nonpolar solvent is used when the amount of carriers injected from the hole injection layer 5 to the light emitting layer 4 is excessive, and the amount of carriers injected from the hole injection layer 5 to the light emitting layer 4 is If it is insufficient, a polar solvent is used. In FIG. 5, the second organic solvent layer S <b> 2 is described as a continuous layer. However, the organic solvent constituting the second organic solvent layer S <b> 2 is formed in an island shape at the interface between the hole injection layer 5 and the light emitting layer 4. (Sparsely) may be arranged and does not necessarily have to be formed as a continuous layer.

  The third organic solvent layer S3 includes an organic solvent having a thickness of one molecular layer to several molecular layers at the interface between the light emitting layer 4 and the electron injection layer 6. The organic solvent is not particularly limited as long as it does not deteriorate the light emitting layer 4 and the electron injection layer 6, and may generally be used for manufacturing an organic EL element. As the organic solvent material, a nonpolar solvent is used when the carrier injection amount from the light emitting layer 4 to the electron injection layer 6 is excessive, and the carrier injection amount from the light emitting layer 4 to the electron injection layer 6 is insufficient. In some cases, a polar solvent is used. In FIG. 5, the third organic solvent layer S3 is described as a continuous layer, but the organic solvent constituting the third organic solvent layer S3 is formed in an island shape at the interface between the light emitting layer 4 and the electron injection layer 6 ( May be arranged sparsely and need not necessarily be formed as a continuous layer.

  The fourth organic solvent layer S4 includes an organic solvent having a thickness of one molecular layer to several molecular layers at the interface between the electron injection layer 6 and the second electrode 8. The organic solvent is not particularly limited as long as it does not deteriorate the electron injection layer 6 and the second electrode 8, and may be generally used for manufacturing an organic EL element. As the organic solvent material, a nonpolar solvent is used when the amount of carriers injected from the electron injection layer 6 to the second electrode 8 is excessive, and the amount of carriers injected from the electron injection layer 6 to the second electrode 8 is as follows. If it is insufficient, a polar solvent is used. In FIG. 5, the fourth organic solvent layer S <b> 4 is described as a continuous layer, but the organic solvent constituting the fourth organic solvent layer S <b> 4 is formed in an island shape at the interface between the electron injection layer 6 and the second electrode 8. (Sparsely) may be arranged and does not necessarily have to be formed as a continuous layer.

  In the organic EL device EL2 having the above configuration, since a plurality of layers including the light emitting layer 4 are formed between the first electrode 3 and the second electrode 8, the carrier is more than the organic EL device EL1 of the first embodiment. An organic EL device with high injection efficiency can be provided. In recent years, the organic EL element 9 has been multilayered, and other organic layers such as the electron injection layer 6 and the hole injection layer 5 are often stacked above and below the light emitting layer 4 in many cases. In such an organic EL device, the carrier injection amount may be controlled on both the second electrode 8 side and the first electrode 3 side. However, in the organic EL device EL2 of the present embodiment, carrier injection is performed at any interface. Since the amount can be controlled, high carrier injection property and optimum carrier balance can be realized at the same time, and the organic EL element 9 can be driven with low voltage and high efficiency. In addition, by inserting an organic solvent between layers or between layers and electrodes, deterioration due to a chemical reaction at these interfaces is suppressed, so the carrier injection amount is less likely to decrease. The organic EL element 9 can be realized. Furthermore, since the carrier injection amount can be controlled without changing the material and configuration of the layers and electrodes, it is necessary to search for a new material and configuration having a desired injection property and injection stability as in the past. There is no. As a result, the development cost can be reduced, and the organic EL device EL2 equipped with the high-quality organic EL element 9 can be provided at a low price.

  In the present embodiment, the functional layer 7 disposed between the first electrode 3 and the second electrode 8 is formed of three layers of the hole injection layer 5, the light emitting layer 4, and the electron injection layer 6. The configuration of the layer 7 is not limited to this, and for example, a hole transport layer is formed between the hole injection layer 5 and the light emitting layer 4 or an electron transport is performed between the light emitting layer 4 and the electron injection layer 6. A layer can also be formed. When the functional layer 7 is formed of a plurality of layers as described above, the layer or electrode disposed on the organic solvent layer is not so washed away that the organic solvent adhering to the surface of the underlying electrode or layer is washed away. It is desirable to laminate by a dry process such as a vacuum evaporation method.

[Image forming apparatus]
Next, an image forming apparatus that is a first embodiment of an electronic apparatus including the light emitting device of the present invention will be described. FIG. 6 is a schematic configuration diagram illustrating an image forming apparatus 100 including an organic EL device as a line head.

  The image forming apparatus 100 includes a photosensitive drum 16 as an image carrier in the vicinity of the travel path of the transfer medium 22. Around the photosensitive drum 16, an exposure device 15, a developing device 18, and a transfer roller 21 are sequentially arranged along the rotation direction of the photosensitive drum 16 (indicated by an arrow in the drawing). The photosensitive drum 16 is rotatably provided around the rotation shaft 17, and a photosensitive surface 16 </ b> A is formed on the outer peripheral surface of the photosensitive drum 16 at the central portion in the rotation axis direction. The exposure device 15 and the developing device 18 are arranged in a long axis shape along the rotation shaft 17 of the photosensitive drum 16, and the width in the long axis direction substantially coincides with the width of the photosensitive surface 16A.

  In this image forming apparatus 100, first, in the process of rotating the photosensitive drum 16, the surface of the photosensitive drum 16 (photosensitive surface 16 </ b> A) is positive (for example, positive) by a charging device (not shown) provided on the upstream side of the exposure device 15. Then, the exposure device 15 exposes the surface of the photosensitive drum 16 to form an electrostatic latent image LA on the surface. Further, the toner (developer) 20 is applied to the surface of the photosensitive drum 16 by the developing roller 19 of the developing device 18, and the toner image corresponding to the electrostatic latent image LA is formed by the electric attractive force of the electrostatic latent image LA. It is formed. The toner particles are positively (+) charged.

  After the toner image is formed by the developing device 18, the toner image comes into contact with the transfer medium 22 by further rotation of the photosensitive drum 16, and the transfer roller 21 has a polarity opposite to that of the toner particles of the toner image from the back surface of the transfer medium 22. Charge (here, negative (−) charge) is applied, and accordingly, toner particles forming a toner image are attracted from the surface of the photosensitive drum 16 to the transfer medium 22, and the toner image is transferred to the surface of the transfer medium 22. Is transcribed.

  The exposure apparatus 15 includes a line head 1 having a plurality of organic EL elements 9 and an imaging optical element 12 having a plurality of lens elements 13 for imaging the light L emitted from the line head 1 at an erecting equal magnification. I have. The line head 1 and the imaging optical element 12 are held by a head case (not shown) while being aligned with each other, and are fixed on the photosensitive drum 16.

  The line head 1 includes a light emitting element array 10 in which a plurality of organic EL elements 9 are arranged along the rotation axis 17 of the photosensitive drum 16, and a drive element group including a drive element (not shown) that drives the organic EL elements 9. And a control circuit group 11 for controlling driving of these drive elements (drive element group). The organic EL element 9, the drive element group, and the control circuit group 11 are integrally formed on a long and thin element substrate (base) 2.

  The imaging optical element 12 is arranged (arranged) in a zigzag pattern in which the lens elements 13 having the same configuration as the SELFOC (registered trademark) lens element manufactured by Nippon Sheet Glass Co., Ltd. are arranged along the rotation axis 17 of the photosensitive drum 16. A lens element array 14 is provided.

  In this image forming apparatus 100, the organic EL element 9 formed on the line head 1 has the structure of the light emitting element of the present invention described above. Therefore, the image forming apparatus has high emission luminance and no exposure failure occurs.

[Organic EL display device]
Next, an organic EL display device that is a second embodiment of an electronic apparatus including the light emitting device of the present invention will be described. FIG. 7 is a schematic configuration diagram of an organic EL display device 200 including organic EL elements as pixels in a matrix.

  The organic EL display device 200 includes a circuit element unit 30 including a thin film transistor as a circuit element, a pixel electrode (first electrode) 3 serving as an anode, an organic functional layer 7 including a light emitting layer, and a counter electrode serving as a cathode. (Second electrode) 8, a sealing portion 32, and the like are provided.

  For example, a glass substrate is used as the substrate 2. As a substrate in the present invention, in addition to a glass substrate, various known substrates used for electro-optical devices and circuit substrates such as a silicon substrate, a quartz substrate, a ceramic substrate, a metal substrate, a plastic substrate, and a plastic film substrate are applied. The

  On the base 2, a plurality of pixel areas A as light emitting areas are arranged in a matrix, and when performing color display, for example, corresponding to each color of red (Red), green (Green), and blue (Blue). The pixel area A to be formed is formed in a predetermined arrangement. In each pixel region A, a pixel electrode 3 is arranged, and in the vicinity thereof, a signal line 42, a common power supply line 43, a scanning line 41, a scanning line for other pixel electrodes (not shown), and the like are arranged. As the planar shape of the pixel region A, an arbitrary shape such as a circle or an oval can be applied in addition to the rectangle shown in the figure.

  The sealing portion 32 prevents water and oxygen from entering and prevents the counter electrode 8 or the organic functional layer 7 from being oxidized, and includes a sealing substrate (or sealing can) 34 bonded to the base 2. The sealing substrate 34 is made of glass, metal, or the like, and the base 2 and the sealing substrate 34 are bonded together with a sealing agent. A desiccant is disposed inside the substrate 2, and an inert gas filling layer 33 filled with an inert gas is formed in a space formed between the substrates.

  In the pixel region A, a first thin film transistor 44 for switching in which a scanning signal is supplied to the gate electrode through the scanning line 41 and a holding for holding an image signal supplied from the signal line 42 through the thin film transistor 44. The capacitor cap, the driving second thin film transistor 45 to which the image signal held by the holding capacitor cap is supplied to the gate electrode, and the common supply line when electrically connected to the common power supply line 43 through the thin film transistor 45 A pixel electrode 3 into which a drive current flows from the electric wire 43 and an organic functional layer 7 sandwiched between the pixel electrode 3 and the counter electrode 8 are provided. The organic functional layer 7 includes a light emitting layer, and the organic EL element 9 which is a light emitting element includes the pixel electrode 3, the counter electrode 8, the organic functional layer 7, and the like.

  In the pixel area A, when the scanning line 41 is driven and the first thin film transistor 44 is turned on, the potential of the signal line 42 at that time is held in the holding capacitor cap, and the second capacitance is changed according to the state of the holding capacitor cap. The conductive state of the thin film transistor 45 is determined. In addition, a current flows from the common power supply line 43 to the pixel electrode 3 through the channel of the second thin film transistor 45, and further a current flows to the counter electrode 8 through the organic functional layer 7. And according to the electric current amount at this time, the organic functional layer 7 light-emits.

  In the organic EL display device 200, light emitted from the organic functional layer 7 to the base 2 side is transmitted through the circuit element unit 30 and the base 2 and emitted to the lower side (observer side) of the base 2. Light emitted from the functional layer 7 to the opposite side of the substrate 2 is reflected by the counter electrode 8, and the light passes through the circuit element unit 30 and the substrate 2 and is emitted to the lower side (observer side) of the substrate 2. (Bottom emission type). Note that light emitted from the counter electrode can be emitted by using a transparent material as the counter electrode 8 (top emission type). In this case, ITO, Pt, Ir, Ni, or Pd can be used as the transparent material for the counter electrode.

  In this organic EL display device 200, the organic EL element 9 formed in the pixel region A has the structure of the light emitting element of the present invention described above. Therefore, an organic EL display device with high emission luminance and capable of bright display is obtained.

[Light emitting diode]
Next, a light emitting diode (LED) which is a third embodiment of an electronic apparatus including the light emitting device of the present invention will be described. FIG. 8 is a schematic configuration diagram of a light emitting diode 300 including an inorganic light emitting element as a light emitting unit.

  The light emitting diode 300 includes an LED chip 9 that is a light emitting element and a support (stem) 61 that supports the LED chip 9. The support body 61 is formed in a substantially cylindrical shape, and a concave portion 69 for accommodating the LED chip 9 is formed at the center of the support body 61. The LED chip 9 is bonded to the bottom surface of the recess 69 via an Ag paste 62 or the like. The support 61 is provided with an inner lead 63 and a mount lead 64. The inner lead 63 and the n-side extraction electrode of the LED chip 9 are connected by a gold wire 65, and the mount lead 64 and the p-side of the LED chip 9 are connected. The extraction electrode is connected by a gold wire 66. A flange portion 68 is provided on the outer peripheral portion of the support 61, a transparent cap 67 is disposed on the flange portion 68, and the LED chip 9 is hermetically sealed.

  In this light emitting diode 300, the LED chip 9 has the structure of the light emitting element of the present invention described above. Therefore, the light emitting diode has high emission luminance and can be driven at a low voltage.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention. In the above embodiment, an organic EL device has been described as an example of a light emitting device. However, the present invention is not limited to an organic EL device, and an inorganic thin film including at least one inorganic thin film including a light emitting layer is sandwiched between a pair of upper and lower electrodes. The present invention can also be applied to other light emitting devices such as an EL device and an inorganic LED (Light Emitting Diode).

It is a schematic block diagram of the organic electroluminescent apparatus which is 1st Embodiment of a light-emitting device. It is explanatory drawing explaining the effect | action of the organic solvent layer in which the same organic EL apparatus was provided. It is explanatory drawing explaining the effect | action of the organic solvent layer in which the same organic EL apparatus was provided. It is explanatory drawing explaining the manufacturing method of the same organic EL device. It is a schematic block diagram of the organic electroluminescent apparatus which is 2nd Embodiment of a light-emitting device. 1 is a schematic configuration diagram of an image forming apparatus that is a first embodiment of an electronic apparatus. It is a schematic block diagram of the organic electroluminescence display which is 2nd Embodiment of an electronic device. It is a schematic block diagram of the light emitting diode which is 3rd Embodiment of an electronic device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Substrate body, 3 ... 1st electrode, 4 ... Light emitting layer, 5 ... Hole injection layer, 6 ... Electron injection layer, 7 ... Functional layer, 8 ... 2nd electrode, 9 ... Organic EL element (light emitting element), DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus (electronic device), 200 ... Organic EL display device (electronic device), 300 ... Light emitting diode (electronic device), EL1, EL2 ... Organic EL device (light emitting device), S, S1, S2, S3 S4 ... Organic solvent layer, Sm ... Organic solvent

Claims (13)

  A functional layer including one or two or more layers including a light emitting layer; and a pair of electrodes sandwiching the functional layer; and an interface between two adjacent layers or the adjacent layer and the electrode An organic solvent is disposed at the interface of the light emitting device.   The organic solvent is disposed only at an interface between two layers adjacent to each other or an interface between the layer adjacent to each other and the electrode, and is not disposed inside the layer or the electrode. Item 4. The light emitting device according to Item 1.   The light-emitting device according to claim 1, wherein the organic solvent is an organic solvent that does not dissolve the layer or the electrode.   The light-emitting device according to claim 1, wherein the organic solvent is a polar solvent.   The light emitting device according to claim 4, wherein a relative dielectric constant of the organic solvent is 10 or more.   5. The organic solvent is disposed at a thickness of one molecular layer to several molecular layers at an interface between two layers adjacent to each other or an interface between the layers adjacent to each other and the electrode. 5. The light emitting device according to 5.   The light-emitting device according to claim 1, wherein the organic solvent is a nonpolar solvent. A method of manufacturing a light emitting device comprising a functional layer including one or two or more layers including a light emitting layer, and a pair of electrodes sandwiching the functional layer,
The surface of the layer or the electrode is exposed to an atmosphere filled with an organic solvent, and the other layer or the other electrode is formed in a state where molecules of the organic solvent are interposed on the surface of the layer or the electrode. A method for manufacturing a light-emitting device.   The method of manufacturing a light emitting device according to claim 8, wherein the other layer or the other electrode is formed by a dry process.   The method for manufacturing a light emitting device according to claim 8, wherein the layer or the electrode is formed by a dry process.   The amount of the organic solvent attached to the surface of the layer or the electrode is controlled by a time during which the surface of the layer or the electrode is exposed to an atmosphere filled with the organic solvent. The manufacturing method of the light-emitting device in any one of items.   When exposing the surface of the layer or the electrode to the atmosphere filled with the organic solvent, the temperature of the surface of the layer or the electrode, the temperature of the atmosphere, and the temperature of the organic solvent are set to constant temperatures, respectively. The method of manufacturing a light emitting device according to claim 11, wherein   An electronic device comprising the light emitting device according to any one of claims 1 to 7 or the light emitting device manufactured by the method for manufacturing a light emitting device according to any one of claims 8 to 12. machine.

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