JP5042685B2 - Organic EL device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an organic EL (electroluminescence) element and a manufacturing method thereof.

  The organic EL device includes an organic layer such as a light emitting layer containing a light emitting organic compound between a hole injection electrode (anode) and an electron injection electrode (cathode). It is an element that excites and emits light by applying an electric field.

  Such an organic EL element is a self-luminous device that emits light from a light-emitting organic compound itself, and does not require a backlight on the back like a liquid crystal. Further, the organic EL element emits light only in a region to which an electric field is applied, that is, a region sandwiched between the anode and the cathode (light emitting region), and a region in which no electric field is applied, that is, a region not sandwiched between the anode and the cathode. Little light is emitted in the (non-light emitting region). Furthermore, many compounds used for the organic layer of the organic EL element have light-transmitting properties.

Because of these characteristics, the organic EL element is expected to be applied to a see-through display device. A see-through display device is a device through which a background can be seen. In the organic EL element, at least a non-light-emitting region having light transmittance may be used as a see-through display device. Specific examples of the organic EL element that can be used as a see-through display device include, for example, an organic EL element that uses a transparent electrode as a hole injection electrode and an electron injection electrode disclosed in Patent Document 1.
JP 2001-176664 A

  However, when producing a see-through display device from a conventional organic EL element, there are the following problems.

  That is, many of the light-emitting organic compounds used in the organic layer have optical absorption in the visible light region (wavelength range of about 400 to about 700 nm). When such a compound is used, since the organic layer is colored, there is a problem that it is difficult to recognize the background of the display device even if a compound having light transmittance is used for the organic layer.

  Therefore, an object of the present invention is to provide an organic EL device that can sufficiently recognize the background even when a compound having optical absorption in the visible light region is used for the organic layer, and a method for manufacturing the same.

  As a result of diligent research, the inventors of the present invention have a first electrode, a second electrode disposed opposite to the first electrode, the opposing surface being smaller than the area of the opposing surface of the first electrode, The above problem is solved by a method for manufacturing an organic EL element in which light is irradiated from the second electrode side to a structure including one or more organic layers disposed between one electrode and a second electrode. I found out that I can do it.

  According to such a manufacturing method, an organic EL element capable of sufficiently recognizing the background can be obtained even when a compound having optical absorption in the visible light region is used for the organic layer. The reason is considered as follows.

  In the manufacturing method of the present invention, the second electrode acts as a mask, and light is irradiated to a region of the organic layer that is not blocked by the second electrode. In the region irradiated with light, a compound having optical absorption in the visible light region is photooxidized, and an oxide having sufficiently small optical absorption in the visible light region is generated. Thereby, the light transmittance of the region irradiated with light in the organic layer, that is, the region not having the second electrode on the upper side is sufficiently improved, and the background of the organic EL element can be sufficiently recognized. . Furthermore, since the second electrode acts as a mask, a compound having optical absorption in the visible light region hardly reacts in the region covered with the second electrode in the organic layer. Therefore, the function as an organic EL element is ensured.

  Further, in such a manufacturing method, since the second electrode acts as a mask, the positional deviation between the region where the compound is oxidized and the non-light emitting region is sufficiently small, for example, less than 10 μm. Therefore, it does not cause an unpleasant appearance due to the shift between the position where the compound is oxidized and the non-light emitting area.

  The organic EL device of the present invention is obtained by the production method of the present invention. The organic EL device of the present invention has the excellent effects described above.

  The present invention also includes a first electrode, one or more organic layers disposed on the first electrode, and a second electrode disposed on the organic layer so as to face the first electrode. The opposing surface of the second electrode is smaller than the area of the opposing surface of the first electrode, and the maximum optical absorptance of the region of the organic layer having the second electrode on the top is An organic EL element having a larger maximum optical absorptance than a region of an organic layer having no second electrode is provided. Here, the “maximum optical absorptance” indicates the maximum absorptance in the optical absorption spectrum in the visible light region to be measured.

  According to such an organic EL element, the background can be sufficiently recognized even when a compound having absorption in the visible light region is used for the organic layer.

  In the organic EL device of the present invention, it is preferable that the maximum optical absorptance of the region of the organic layer not having the second electrode on the upper portion is 10% or less. According to this, the background of the organic EL element can be recognized more reliably.

  The present invention further includes a first electrode, one or more organic layers disposed on the first electrode, and a second electrode disposed on the organic layer so as to face the first electrode. An organic EL element comprising: a visible light having a surface facing the second electrode smaller than an area of the surface facing the first electrode, wherein at least one organic layer contains a compound having optical absorption in the visible light region The amount of oxide of the compound per unit volume of the region of the visible light absorbing organic layer having the second electrode on the upper portion of the absorbing organic layer is larger than that of the region of the visible light absorbing organic layer not having the second electrode on the upper portion. Provided is an organic EL device having a smaller amount of oxide of the above compound per unit volume.

  According to such an organic EL element, in the region of the visible light absorbing organic layer not having the second electrode on the upper portion, the amount per unit volume of the oxide having sufficiently small optical absorption in the visible light region is sufficiently large. Therefore, the background can be sufficiently recognized.

  In the organic EL device of the present invention, the oxide amount of the above compound per unit volume in the region of the visible light absorbing organic layer not having the second electrode on the top is preferably 70% by mass or more. According to this, the background of the organic EL element can be recognized more reliably.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the compound which has optical absorption in visible region is used for an organic layer, the organic EL element which can fully recognize a background, and its manufacturing method can be provided. Furthermore, according to the organic EL element obtained by the manufacturing method of the present invention, the appearance of the organic layer region not having the second electrode on the upper portion and the non-light emitting region are not deteriorated.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as the case may be, but the present invention is not limited to the following embodiments. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

[Method of manufacturing organic EL element]
FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of a method for producing an organic EL element of the present invention.

  A structure 100 that can be manufactured by a conventionally known method shown in FIG. 1 includes a substrate 4, a first electrode 1, an organic layer 6, and a second electrode 2 that has a smaller principal surface area than the first electrode. . The first electrode 1 is provided on the substrate 4, the organic layer 6 is provided so as to cover the first electrode 1 and the substrate 4, and the second electrode 2 is organic so as to face the first electrode. It is provided on the layer 6. The organic layer 6 contains an organic compound having optical absorption in the visible light region.

  An organic compound having optical absorption in the visible light region is an organic compound having optical absorptivity, and when irradiated with light, causes optical oxidation, photoisomerization, photolysis, and the like, resulting in a decrease in optical absorptance. I just need it. Preferred examples thereof include condensed polycyclic aromatic amine derivatives, organic compounds having a heterocondensed polycyclic aromatic skeleton, pyrrole derivatives, organic compounds having a pyromethene skeleton, phthalocyanine derivatives, organometallic complexes (central metals Al, Ir , Pt, Cu, Ru), and quinolinol metal complexes. Among them, naphthacene derivatives, aminoanthracene derivatives, anthracene derivatives, aminoanthracene derivatives, pentacene derivatives, perylene derivatives, indenoperylene derivatives, diindenoperylene derivatives, coumarin derivatives, benzofluoranthene derivatives, phenanthroline derivatives, and phenanthrene derivatives More preferred. Such an organic compound having optical absorption in the visible light region may be a light-emitting organic compound or an organic compound having other functions.

  Organic compounds having optical absorption in the visible light region include naphthacene skeleton, aminoanthracene skeleton, anthracene skeleton, aminoanthracene skeleton, pentacene skeleton, perylene skeleton, indenoperylene skeleton, diindenoperylene skeleton, coumarin skeleton, and benzoflurane. A polymer compound having an optically absorbing skeleton such as an olanthene skeleton, a phenanthroline skeleton, or a phenanthrene skeleton in a conjugated portion or a side chain portion may be used.

  Moreover, the organic layer 6 in the structure 100 may be composed of a single light-emitting layer containing a light-emitting organic compound, or may be composed of a plurality of layers having different functions.

  By irradiating the structure 100 with light from the second electrode 2 side, an organic compound having optical absorption in the visible light region of the organic layer 6 that does not have the second electrode on the upper side is oxidized, and FIG. The organic EL element 200 of this embodiment shown in FIG. In addition, it is preferable that the light in this manufacturing method is UV light (ultraviolet rays) from a viewpoint of oxidizing an organic compound having optical absorption in the visible light region more efficiently.

[Organic EL device]
FIG. 2 is a schematic cross-sectional view showing the first embodiment of the organic EL element according to the present invention, which is obtained by the manufacturing method described above. In the organic EL element 200, the organic compound having optical absorption in the visible light region is hardly oxidized in the region 7 having the second electrode 2 in the upper portion of the organic layer 6. Further, in the region 8 that does not have the second electrode 2 in the upper portion, a large amount of organic compound oxide having optical absorption in the visible light region is contained, for example, 70 mass% or more per unit volume. This oxide has a sufficiently small optical absorption in the visible light region. Therefore, the maximum optical absorptance of the region 8 is sufficiently low, for example, 10% or less, and the background of the organic EL element 200 can be sufficiently recognized.

  When a voltage is applied to such an organic EL element from the first electrode 1 and the second electrode 2, the region 7 emits light when viewed from the substrate 4 side, and the region 8 has a background. Can be fully recognized. Moreover, if the patterned 2nd electrode is used, light emission according to the pattern can also be obtained. In addition, the width | variety at the time of forming a pattern can be 10-1000 micrometers, for example.

  FIG. 3 is a schematic cross-sectional view showing a second embodiment of the organic EL element according to the present invention. The organic EL element 300 shown in FIG. 3 includes the first electrode 1, the light emitting layer 10 provided on the first electrode 1, and the area of the main surface from the first electrode provided on the light emitting layer 10. And the second electrode 2 having a small size.

  FIG. 4 is a schematic cross-sectional view showing a third embodiment of the organic EL element according to the present invention. The organic EL element 400 shown in FIG. 4 includes a hole transport layer 11, a light emitting element, and a first electrode 1 disposed opposite to each other and a second electrode 2 having a smaller principal surface area than the first electrode. The layer 10 and the electron transport layer 12 are sandwiched. The hole transport layer 11, the light emitting layer 10, and the electron transport layer 12 all correspond to organic layers, and are laminated in this order from the first electrode 1 side.

  Although not shown, the organic EL elements 300 and 400 shown in FIGS. 3 and 4 are similar to the organic EL element shown in FIG. 2 in a region where the second electrode is not provided on the light emitting layer 10. It contains a large amount of an organic compound oxide having optical absorption in the visible light region, and its background can be sufficiently recognized.

  In the organic EL elements 300 and 400, the first electrode 1 is formed on the substrate 4. Further, although not shown, a plurality of light emitting layers containing different constituent materials (type of material, content ratio of materials) may be provided as a light emitting layer.

  In the above embodiment, the first electrode 1 and the second electrode 2 function as a hole injection electrode (anode) and an electron injection electrode (cathode), respectively. While holes (holes) are injected and electrons are injected from the second electrode 2, the light-emitting organic compound in the light-emitting layer 10 (the organic layer 6 in the first embodiment) is formed based on these recombination. Emits light.

  In such an organic EL element, preferred thicknesses of the light emitting layer 10, the hole transport layer 11, and the electron transport layer 12 are all 5 to 200 nm.

(substrate)
As the substrate 4, an amorphous substrate such as glass or quartz, a crystal substrate such as Si, GaAs, ZnSe, ZnS, GaP, or InP, or a metal substrate such as Mo, Al, Pt, Ir, Au, Pd, or SUS is used. Can be used. Further, a thin film made of a crystalline or amorphous ceramic, metal, organic substance or the like formed on a predetermined substrate may be used. Among these, from the viewpoint of the transparency of the substrate, a substrate such as glass or quartz is preferably used, and in particular, an inexpensive glass substrate is preferably used. The substrate may be provided with a color filter film, a color conversion film containing a fluorescent material, a dielectric reflection film, or the like for adjusting the color light.

(First electrode)
The first electrode 1 functions as a hole injection electrode (anode). Therefore, the material of the first electrode 1 is preferably a material that can efficiently inject holes into the organic layer adjacent to the first electrode 1, and from this point of view, a material having a work function of 4.5 to 5.5 eV. Is preferred.

  Further, the transmittance of the first electrode 1 at a wavelength of 400 to 700 nm which is an emission wavelength region of the organic EL element, particularly at each wavelength of RGB is preferably 50% or more, and more preferably 80% or more. More preferably, it is 90% or more. When the transmittance of the first electrode 1 is less than 50%, the light emission from the light emitting layer 10 is attenuated, and it is difficult to obtain the luminance necessary for image display.

The 1st electrode 1 with high light transmittance can be comprised using the transparent conductive film comprised with various oxides. As such a material, indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), and the like are preferable. It is particularly preferable in that a thin film having a uniform in-plane specific resistance can be easily obtained. The ratio of SnO ₂ to In ₂ O _{3 in} ITO is preferably 1 to 20% by mass, and more preferably 5 to 12% by mass. The ratio of ZnO to In ₂ O ₃ in IZO is preferably 12 to 32% by mass. The said material may be used individually by 1 type, and may be used in combination of 2 or more type.

Note that the composition of the oxide constituting the first electrode 1 may be slightly deviated from the stoichiometric composition. For example, ITO usually contains In ₂ O ₃ and SnO _{2 in a} stoichiometric composition, but when the composition of ITO is represented by InOx · SnOy, x is in the range of 1.0 to 2.0, y May be in the range of 0.8 to 1.2.

Further, the work function of the first electrode 1 can be adjusted by adding a transparent dielectric such as silicon oxide (SiO ₂ ) to the first electrode 1. For example, the work function of ITO can be increased by adding about 0.5 to 10 mol% of SiO ₂ with respect to ITO, and the work function of the first electrode 1 can be within the above-mentioned preferable range.

  The thickness of the first electrode 1 is preferably determined in consideration of the above-described light transmittance. For example, when using an oxide transparent conductive film, the thickness is preferably 50 to 500 nm, more preferably 50 to 300 nm. When the thickness of the first electrode 1 exceeds 500 nm, the light transmittance may be insufficient and the first electrode 1 may be peeled off from the substrate 4 in some cases. In addition, the light transmittance improves as the thickness decreases. However, when the thickness is less than 50 nm, the hole injection efficiency into the light emitting layer 10 or the like tends to decrease and the strength of the film tends to decrease.

(Second electrode)
The second electrode 2 functions as an electron injection electrode (cathode). Examples of the material of the second electrode 2 include a metal material, an organometallic complex, a metal salt, and the like, and a material having a low work function is preferable so that electron injection into the light emitting layer 10 and the like is easy.

  Specific examples of the metal material constituting the second electrode 2 include alkali metals such as Li, Na, K, and Cs, alkaline earth metals such as Mg, Ca, Sr, and Ba, and alkali metals such as LiF and CsI. And halides. Alternatively, a metal having properties similar to those of an alkali metal or an alkaline earth metal such as La, Ce, Sn, Zn, or Zr can be used. Among these, Ca is particularly preferable because it has a very low work function.

  When an alkali metal or alkaline earth metal is used as the second electrode 2, the thickness is preferably 0.1 to 100 nm, more preferably 1.0 to 50 nm. Further, the thickness in the case of using an alkali halide as the second electrode 2 is preferably as thin as possible from the viewpoint of the ability to inject electrons into the light emitting layer 10, and specifically, it is preferably 10 nm or less, more preferably 1 nm or less. preferable. The second electrode 2 made of the above material can be formed by, for example, a vacuum deposition method or the like.

  Specific examples of the organometallic complex constituting the second electrode 2 include a β-diketonato complex and a quinolinol complex. The metal of the organometallic complex should preferably have a low work function. For example, alkali metals such as Li, Na, K, and Cs, alkaline earth metals such as Mg, Ca, Sr, and Ba, and La and Ce A metal having properties close to those of an alkali metal or alkaline earth metal such as Sn, Zn, or Zr is preferable.

  The second electrode 2 made of the above material is a layer (for example, a light emitting layer) to which the second electrode 2 is connected by, for example, a coating solution obtained by adding an organometallic complex to a predetermined solvent by a coating method such as a spin coating method. 10) It can be formed by coating on and removing the solvent from the coating solution.

  Specific embodiments of the metal salt constituting the second electrode 2 include Ag, Al, Au, Be, Bi, Co, Cu, Fe, Ga, Hg, Ir, Mo, Mn, Nb, Ni, Os, and Pb. , Pd, Pt, Re, Ru, Sb, Sn, Ti, Zr and the like.

  These metal salts may be either organic metal salts or inorganic metal salts. Examples of the organic metal salts include substituted or unsubstituted aliphatic carboxylates, divalent carboxylates, aromatic carboxylates, alcoholates, phenolates, dialkylamides, and the like. Examples of the inorganic metal salt include halides.

  The aliphatic carboxylic acid of the aliphatic carboxylate may be either a saturated aliphatic carboxylic acid or an unsaturated aliphatic carboxylic acid. Examples of the saturated aliphatic carboxylate include metal salts such as acetic acid, propionic acid, octanoic acid, isooctanoic acid, decanoic acid, and lauric acid. Examples of the unsaturated aliphatic carboxylate include metal salts such as oleic acid, ricinoleic acid, and linoleic acid.

  Examples of the divalent carboxylate include metal salts of divalent carboxylic acids such as citric acid, malic acid, and oxalic acid. Examples of the aromatic carboxylate include benzoic acid, o-tert-butylbenzoic acid, m Examples include metal salts such as -tert-butylbenzoic acid, p-tert-butylbenzoic acid, salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, and among them, the metal salt of salicylic acid is preferable.

  An alcoholate is a metal salt of an alcohol. Examples of the alcohol component constituting the alcoholate include primary alcohols such as ethanol, n-propyl alcohol and n-butyl alcohol, secondary alcohols such as isopropyl alcohol and isobutyl alcohol, and tertiary alcohols such as tert-butyl alcohol. It is done.

  Phenolate is a metal salt of phenols. The number of hydroxyl groups contained in the phenol component constituting the phenolate is not particularly limited, but is preferably 1 to 2. Such a phenol component may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms) in addition to the hydroxyl group. In the present invention, phenol, naphthol, 4-phenylphenol and the like are preferably used.

  Examples of the halide that is an inorganic metal salt include metal salts such as chlorine, fluorine, bromine, and iodine.

  The second electrode 2 made of the above material is a layer (for example, the light emitting layer 10) to which the second electrode 2 is connected by, for example, a coating solution obtained by adding a metal salt to a predetermined solvent by a coating method such as a spin coating method. It is possible to form the film by applying it on the substrate and removing the solvent from the coating solution.

  The second electrode 2 may be one in which an auxiliary electrode is further provided on the above electrode. According to the second electrode 2 as described above, it is possible to improve the efficiency of electron injection into the light emitting layer 10 and the like, and to prevent moisture or an organic solvent from entering the light emitting layer 10 and the like. As a material for the auxiliary electrode, a general metal can be used because there is no restriction on work function and charge injection capability. However, it is preferable to use a metal having high conductivity and easy handling. In particular, in the case where the second electrode 2 includes an organic material, it is preferable to select appropriately according to the type and adhesion of the organic material.

  Examples of the material used for the auxiliary electrode include Al, Ag, In, Ti, Cu, Au, Mo, W, Pt, Pd, and Ni. Among them, when a low-resistance metal such as Al and Ag is used, electrons are used. The injection efficiency can be further increased. Moreover, higher sealing properties can be obtained by using a metal compound such as TiN. These materials may be used alone or in combination of two or more. Moreover, when using 2 or more types of metals, you may use as an alloy. Such an auxiliary electrode can be formed by, for example, a vacuum deposition method or the like.

  In addition, if what was patterned as the above-mentioned 2nd electrode 2, the light emission according to the pattern can be obtained. Further, when the second electrode 2 further provided with the auxiliary electrode is used, light emission corresponding to the pattern can be obtained also by using a pattern in which only the auxiliary electrode is patterned.

(Light emitting layer)
As the material of the light emitting layer 10, in particular, as long as it is a light emitting organic compound that generates excitons by recombination of electrons and holes and emits energy when the excitons release energy and returns to the ground state, A light-emitting organic compound having optical absorption in the visible light region can also be used without limitation.

  Specific examples thereof include an organometallic complex compound such as an aluminum complex, a beryllium complex, a zinc complex, an iridium complex, or a rare earth metal complex, anthracene, naphthacene, benzofluoranthene, naphthofluoranthene, styrylamine, tetraaryldiamine, or the like. Derivatives, perylene, quinacridone, coumarin, low molecular organic compounds such as DCM or DCJTB, or π-conjugated polymers such as polyacetylene derivatives, polyphenylene vinylene derivatives, polyfluorene derivatives or polythiophene derivatives, or polyvinyl compounds, polystyrene derivatives, polysilanes Derivatives, polyacrylate derivatives, polymethacrylate derivatives and other non-π-conjugated side chain polymers or main chain polymers containing pigments, etc. And high molecular organic compounds. Note that when a light-emitting organic compound having optical absorption in the visible light region is used for the light-emitting layer, the light-emitting layer corresponds to the above-described visible light-absorbing organic layer.

  Further, it is preferable to use a combination of a host material and a dopant material as the constituent material of the light emitting layer 10. By using a dopant material with relatively strong fluorescence, the emission wavelength characteristic of the host material can be changed, and the emission wavelength can be shifted to a longer wavelength, and the emission efficiency and stability of the device are improved. . In such a case, the content of the dopant material in the light emitting layer 10 varies depending on the combination of the host material and the dopant material, but is generally 0.01 to 30.0% by mass, more preferably 0.1 to 10% by mass. % Is preferred.

  As the host material, among the above-mentioned compounds, 1,10-phenanthroline derivatives, organometallic complex compounds, aromatic hydrocarbon compounds such as naphthalene, anthracene, naphthacene, perylene, benzofluoranthene, naphthofluoranthene, and their Derivatives, further styrylamine or tetraaryldiamine derivatives are preferred. As the dopant material, among the above-mentioned compounds, aromatic hydrocarbon compounds such as organometallic complex compounds, naphthalene, anthracene, naphthacene, perylene, benzofluoranthene, naphthofluoranthene, and derivatives thereof, and further styrylamine or Tetraaryldiamine derivatives or quinacridone, coumarin, DCM and their derivatives are preferred.

  The light emitting layer 10 is also preferably a mixed layer of at least one or more hole transporting compounds and at least one or more electron transporting compounds as required, and more preferably when a dopant is contained in the mixed layer. preferable. In the mixed layer, a carrier hopping conduction path is generated, and each carrier moves in a polar dominant substance, so that it is considered that carrier injection in the reverse direction is unlikely to occur. Thereby, since the organic material which comprises the light emitting layer 10 becomes difficult to receive a damage, there exists an advantage that the drive life of an organic EL element is extended.

  Examples of the hole transporting compound and electron transporting compound used in the mixed layer include 1,10-phenanthroline derivatives, organometallic complex compounds, aromatic hydrocarbon compounds such as anthracene, naphthacene, benzofluoranthene, naphthofluoranthene, and the like. It is preferable to use a derivative of As the hole transporting compound, it is preferable to use an amine derivative having strong fluorescence. Examples of such an amine derivative include a triphenyldiamine derivative, a styrylamine derivative, and an amine derivative having an aromatic condensed ring.

  In this case, the preferred mixing ratio of the hole transporting compound and the electron transporting compound varies depending on the carrier mobility and the carrier concentration, but generally, the mixing ratio of the hole transporting compound and the electron transporting compound ( (Mass ratio) is preferably 1:99 to 99: 1, more preferably 10:90 to 90:10, and even more preferably about 20:80 to 80:20.

(Hall transport layer)
For the hole transport layer 11, any hole transport material of a low molecular material or a polymer material can be used. Examples of the hole transporting low molecular weight material include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives, tetraphenyldiaminobiphenyl derivatives, and the like. Also, hole transporting polymer materials include polyvinyl carbazole (PVK), polyethylene dioxythiophene (PEDOT), polyethylene dioxythiophene / polystyrene sulfonic acid copolymer (PEDOT / PSS), polyaniline / polystyrene sulfonic acid copolymer. (Pani / PSS). One of these hole transport materials may be used alone, or two or more thereof may be used in combination.

(Electron transport layer)
For the electron transport layer 12, any of electron transport materials of low molecular materials and polymer materials can be used. Examples of the electron transporting low molecular weight material include oxadiazole derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and its derivatives, fluorene And derivatives thereof, diphenyldicyanoethylene and derivatives thereof, phenanthroline and derivatives thereof, and metal complexes having these compounds as ligands. Examples of the electron transporting polymer material include polyquinoxaline and polyquinoline.

  As the constituent material of the electron transport layer 12 described above, one kind may be used alone, or two or more kinds may be used in combination.

  The organic EL device according to the present invention can be manufactured by a known manufacturing method except that light is irradiated from the second electrode 2 side. As a method for forming the organic layer, a vacuum vapor deposition method, an ionization vapor deposition method, a coating method, or the like can be appropriately selected and employed depending on the material constituting the organic layer.

Example 1
An ITO transparent electrode (anode) was formed to a thickness of 100 nm on the glass substrate by RF sputtering, and the ITO electrode was patterned on the line. This glass substrate with an ITO transparent electrode was ultrasonically cleaned with a neutral detergent, acetone, and ethanol, dried in an environment of 100 degrees or more, and then the ITO electrode surface was further cleaned with UV light under high concentration oxygen. . Immediately after that, the cleaned substrate was put into a vacuum deposition apparatus and the pressure was reduced to about 1 × 10 ⁻⁴ Pa. At the time of organic layer deposition, the following film formation was performed while maintaining a vacuum degree of about 1 × 10 ⁻⁴ Pa.

  First, a tetraphenyldiaminobiphenyl derivative represented by the following formula (1) was vapor-deposited on the ITO electrode to a film thickness of 50 nm at a vapor deposition rate of about 0.1 nm / second to form a hole transport layer. Further, a naphthacene derivative represented by the following formula (2) was formed into a light emitting layer by forming a film of 40 nm at a deposition rate of about 0.1 nm / second. Thereafter, tris (8-quinolylato) aluminum was deposited to a thickness of 10 nm at a deposition rate of about 0.1 nm / second to form an electron transport layer. Next, while maintaining the reduced pressure state, lithium fluoride was deposited to a thickness of 0.3 nm at a deposition rate of about 0.01 nm / second to form an electron injection electrode (cathode). Further, a patterned organic EL device was obtained by depositing 150 nm of Al as an auxiliary electrode through a deposition mask.

When a current density of 10 mA / cm ² was passed through this element, characteristics with a driving voltage of 5.5 V and an emission luminance of 250 cd / m ² were obtained. The emission color was (0.43, 0.55) in CIE chromaticity coordinates, and patterned green emission was confirmed.

  Thereafter, the entire organic EL device was irradiated with UV light having a peak wavelength of 360 nm from the cathode side in the atmosphere. Table 1 shows the maximum optical absorptance of the organic EL element before irradiation with UV light and after irradiation with UV light for 1, 5 and 10 minutes, respectively. The maximum optical absorptance was calculated as follows.

  That is, using a measuring instrument (Shimadzu Corporation UV3101PC), the transmission spectrum and the absolute reflection spectrum in the visible light region were measured for the portion of each organic EL element where the Al electrode was not formed. The optical absorptance was calculated from the transmissivity and reflectance at each wavelength (formula: optical absorptivity = 1−transmittance−reflectance) to obtain an optical absorption spectrum. The maximum absorption rate in this optical absorption spectrum was defined as the maximum optical absorption rate. For example, the maximum optical absorptance of the organic EL element before UV light irradiation was 27.5% at a wavelength of 510 nm.

  Further, the driving voltage, light emission luminance, and light emission color were measured for the organic EL elements after being irradiated with UV light for 1, 5 and 10 minutes, respectively, and these were all the same values as before UV light irradiation.

(Reference Example 1)
Five glass substrates were prepared, and a naphthacene derivative represented by the above formula (2) was deposited on each glass substrate at a deposition rate of 0.01 nm and a vacuum degree of 1 × 10 ⁻⁴ Pa to a thickness of 40 nm. An organic layer was formed, and five laminates that schematically reproduced the light emitting layer of Example 1 were prepared.

  Four of these laminates were irradiated with UV light having a peak wavelength of 360 nm from the organic layer side for 1, 3, 5, and 10 minutes, respectively. The maximum optical absorptance of the laminate not irradiated with UV light (laminate with a UV light irradiation time of 0 minutes) and the laminate irradiated with UV light for 1, 3, 5 and 10 minutes, respectively, in the organic layer Table 2 shows the ratio per unit volume of the oxide of the naphthacene derivative represented by the above formula (2). Moreover, the optical absorption spectrum in each laminated body is shown in FIG. FIG. 6 is a graph showing the relationship between the maximum optical absorptance with respect to the exposure time and the ratio per unit volume of the oxide, and FIG. 7 shows the relationship between the ratio per unit volume of the oxide and the maximum optical absorptance. It is a graph which shows a relationship.

  The maximum optical absorptance was measured by the same method as in Example 1, and the ratio of the oxide per unit volume was measured as follows. That is, each organic layer of the laminate was dissolved in a toluene solvent to obtain a solution having a concentration of about 200 ppm. The obtained solution was subjected to purity analysis using high performance liquid chromatography (HEWLETT PACKARD G1312A) to measure the ratio of the oxide per unit volume.

  In addition, when the coloration of each laminate was confirmed by visual observation, coloration was a concern for those irradiated with UV light for 1 minute, but for those irradiated with UV light for 3 minutes. The coloring was hardly noticed, and no coloring was observed for those irradiated with UV light for 5 minutes and those irradiated for 10 minutes.

It is a schematic cross section which shows one preferable embodiment of the manufacturing method of the organic EL element of this invention. 1 is a schematic cross-sectional view showing a first embodiment of an organic EL element according to the present invention. It is a schematic cross section which shows 2nd Embodiment of the organic EL element which concerns on this invention. It is a schematic cross section which shows 3rd Embodiment of the organic EL element which concerns on this invention. It is a figure which shows the optical absorption spectrum in a laminated body. It is a graph which shows the relationship between the maximum optical absorptance with respect to exposure time, and the ratio per unit volume of an oxide. It is a graph which shows the relationship between the ratio per unit volume of an oxide, and the maximum optical absorptance.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st electrode, 2 ... 2nd electrode, 4 ... Substrate, 6 ... Organic layer, 10 ... Light emitting layer, 11 ... Hole transport layer, 12 ... Electron transport layer, 100 ... Structure, 200, 300, 400 ... Organic EL element, P ... Power supply.

Claims (4)

A first electrode made of a transparent conductive film; a second electrode disposed opposite to the first electrode, the opposing surface of which is smaller than the area of the opposing surface of the first electrode; and the first electrode And one or more organic layers disposed between the second electrode and the second electrode. The structure is provided with light from the second electrode side, and light is emitted from the second electrode of the organic layer. A method for producing a see-through type organic EL element in which at least a non-light emitting region is light transmissive, wherein light is irradiated to a region where light is not blocked ,
The organic layer contains an organic compound having optical absorption in the visible light region,
The method for producing a see-through type organic EL device, wherein the maximum optical absorptance of the region of the organic layer not having the second electrode on the upper portion after the light irradiation is 10% or less. The organic compound having optical absorption in the visible light region includes a condensed polycyclic aromatic amine derivative, an organic compound having a heterocondensed polycyclic aromatic skeleton, a pyrrole derivative, an organic compound having a pyromethene skeleton, a phthalocyanine derivative, and an organometallic complex. (central metal Al, Ir, Pt, Cu, Ru), and at least one organic compound selected from the group consisting of quinolinol metal complex, a manufacturing method of the see-through type organic EL device according to claim 1. The organic compounds having optical absorption in the visible light region include naphthacene derivatives, aminoanthracene derivatives, anthracene derivatives, aminoanthracene derivatives, pentacene derivatives, perylene derivatives, indenoperylene derivatives, diindenoperylene derivatives, coumarin derivatives, benzofluoranes. The method for producing a see-through type organic EL device according to claim 1, which is at least one organic compound selected from the group consisting of a ten derivative, a phenanthroline derivative, and a phenanthrene derivative. See-through type organic EL device obtained by the method according to any one of claims 1 to 3.

Images