JP2002056973A - Organic electroluminescent element and photosensitive polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent element having high color purity due to the utilization of coherence effect obtained by controlling the thickness of a resin layer, and to provide a photosensitive polymer pertinent to a formation of the resin layer. SOLUTION: The organic electroluminescent element has two or more of minimum luminous units emitting different colors from each other on a substrate, and each minimum luminous unit has a resin layer between a positive electrode and a negative electrode, and the thickness of each layer is different from each other in every color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic electroluminescent device and a novel photosensitive polymer. For more information,
The present invention relates to a thin film device that emits light by applying an electric field to a light emitting layer made of an organic compound.

[0002]

2. Description of the Related Art Conventionally, as a thin film type electroluminescent (EL) element, Zn, which is a group II-VI compound semiconductor of an inorganic material, is used.
In general, S, CaS, SrS, and the like are doped with Mn or a rare earth element (Eu, Ce, Tb, Sm, or the like) which is a luminescence center. However, EL devices manufactured from the above inorganic materials include: 1) AC drive is required (50-1000 Hz), 2) High drive voltage (up to 200 V), 3) Full color is difficult (especially blue), 4) Peripheral drive circuit is expensive. I have.

[0003] In recent years, in order to improve the above problems, EL devices using organic thin films have been developed. In particular, in order to enhance the luminous efficiency, the type of the electrode was optimized for the purpose of improving the efficiency of carrier injection from the electrode, and a hole transport layer composed of an aromatic diamine and a luminescent layer composed of an aluminum complex of 8-hydroxyquinoline were used. Of an organic electroluminescent device provided with an electrode (Appl. Phys. Lett., Volume 51, 913
(1987, p. 1987), the luminous efficiency is greatly improved as compared with a conventional EL device using a single crystal such as anthracene or the like, and practical characteristics are approached.

[0004] In addition to the electroluminescent device using a low molecular material as described above, poly (p-phenylenevinylene) (Nature, 347, 539, 1990, etc.)
Poly [2-methoxy-5- (2-ethylhexyloxy) -1,4
-Phenylene vinylene] (Appl. Phys. Lett., Vol. 58,
1982, 1991 etc.), poly (3-alkylthiophene)
(Jpn. J. Appl. Phys, Vol. 30, L1938, 1991, etc.) and the development of electroluminescent devices using polymer materials, as well as low molecular light emitting materials and electron transfer materials for polymers such as polyvinyl carbazole (Applied Physics, 61, 1044, 1992)
Year) is also being developed.

[0005] One of the important issues for a full-color or multi-color display using an organic electroluminescent device is to improve the emission color purity of the device. It has been reported that the light interference effect is used to improve color purity (Synthetic
Metals, 111-112, page 1, 2000). In order to improve the color purity using the light interference effect, it is necessary to optimize the optical path length, that is, the film thickness for each color minimum emission unit, for example, for each of the RGB sub-pixels forming one pixel.

FIG. 1 shows the principle of the optical interference effect. The light exiting the light emitting layer and the light reflected at the ITO / glass interface after exiting the light emitting layer interfere with each other. In the case of the structure shown in FIG.
Considering the reflection at the TO / glass substrate interface, the interference condition is given by the following equation, where L is the difference in optical distance between the direct light and the reflected light: 2L = mλ / 2, where L = L ₂ n ₂ + L ₃ n ₃ n ₂ : refractive index of hole transport layer n ₃ : refractive index of ITO λ: emission wavelength m: integer Further, organic layer and I at emission wavelength corresponding to three primary colors
The values of the refractive index dispersion of the TO electrode layer and the glass substrate are shown in the following table.

[0007]

[Table 1]

(Note that, in the present invention, the term “organic layer” means “a layer made of an organic compound existing between the anode and the cathode”, and includes, for example, a light emitting layer and a hole injection layer described later.) FIG. 2 shows that the ITO film thickness is 1 at the emission wavelengths corresponding to the three primary colors of blue (460 nm), green (520 nm), and red (625 nm).
The result of the light interference characteristic calculated as 00 nm is shown. FIG.
Therefore, the problems of this technology include the following: The optimum film thickness of the element differs depending on the emission color: for example, in the thickness of the hole transport layer where the emission intensity of blue has a maximum value, the emission intensity of red has a minimum value.

[0009] 2. As is clear from FIG. 3, at the blue and green emission wavelengths, the first hole transport layer thickness at which the emission intensity reaches a maximum value is 50 nm or less. Absent. Next, the film thickness of the hole transport layer at which the light emission intensity has a maximum value is about 150 nm, and there is a possibility that the drive voltage may increase with the current conductivity of the hole transport material.

[0010] 3. Normally, since pixels are formed by a vapor deposition process using a shadow mask, when applied to a multi-color or full-color display, the vapor deposition thickness must be changed for each sub-pixel, and the vapor deposition process is troublesome. 4. When patterning sub-pixels using a shadow mask, there is a limit (about 5 microns) in mechanical mask alignment accuracy. Therefore, there is a limit to high-definition patterning, and the effective pixel area decreases.

In order to apply the organic electroluminescent device to a light source such as a flat panel display or a backlight in addition to the improvement of the emission color purity, it is necessary to sufficiently secure the reliability of the device. However, the heat resistance of the conventional organic electroluminescent device is insufficient, and the current-voltage characteristic shifts to a higher voltage side due to an increase in the ambient temperature or process temperature of the device, or local Joule heat generation during device driving. As a result, deterioration such as shortening of service life and generation and increase of non-light-emitting portions (dark spots) cannot be avoided.

Although there are several causes of these instabilities, the main cause of the deterioration is deterioration of the thin film shape of the organic layer. It is considered that the deterioration of the thin film shape is caused by crystallization (or aggregation) of the organic amorphous thin film caused by a temperature rise due to heat generation or the like during element driving. It is considered that this low heat resistance is mainly due to the low glass transition temperature (hereinafter abbreviated as Tg) of the material. Low molecular weight (molecular weight 400
To about 600), especially hole transport materials, often have a low melting point and high symmetry. For example, N, N'-
Diphenyl-N, N '-(3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (usually called TPD) has a Tg of 60
℃, Tg of starburst type aromatic triamine is 75 ℃ (J.
Phys. Chem., 97, 6240, 1993), and 4,4′-bis [N- (1-naphthyl) -N-introduced α-naphthyl group.
The phenylamino] biphenyl has a Tg of 96 ° C (IEICE Technical Report, OME95-54, 1995), and both have highly symmetric structures. The organic amorphous thin film formed from these aromatic amine compounds crystallizes due to an increase in temperature or causes an interdiffusion phenomenon in a two-layer element structure of a hole transport layer and a light emitting layer. As a result, the light emitting characteristics of the device, particularly, a deterioration phenomenon such as a decrease in luminance and an increase in drive voltage appear, and ultimately leads to a reduction in drive life. In addition, even when the element is not driven, the temperature is expected to increase in the steps of vapor deposition, baking (annealing), wiring, sealing, and the like during the production of the element.

On the other hand, attempts have been made to form a hole transport layer of an organic electroluminescent device using a polymer material instead of a low molecular weight compound. For example, polyvinyl carbazole (IEICE Technical Report, OME90-38, 1990
Year), polysilane (Appl. Phys. Lett., Vol. 59, 2760)
P. 1991), and polyphosphazene (the 42nd Annual Meeting of the Society of Polymer Science, I-8-07 and I-8-08, 1993).

However, polyvinyl carbazole has a temperature of 200 ° C.
However, durability is low due to problems such as trapping holes. The driving life of polysilane is as short as several seconds due to light deterioration or the like. Polyphosphazene has a high ionization potential and does not show properties superior to conventional aromatic diamines. In addition, a hole transport layer in which an aromatic diamine compound is dispersed in a polycarbonate or PMMA at 30 to 80% by weight has been studied (Jpn. J. Appl. Phys., 31).
Vol. L960, p. 1992), a low-molecular compound acts as a plasticizer to lower Tg, and the device characteristics are also lower than when an aromatic diamine compound is used alone.

Further, among the polyethers containing an aromatic diamine which is a hole transporting polymer, those having a Tg exceeding 200 ° C. are disclosed, but the light emitting characteristics and stability of the device are not sufficient (Japanese Patent Laid-Open No. -188756). In addition, a hole transport film in which a hole transport material is dispersed in an organic binder having a cross-linking structure has been reported (JP-A-7-23537).
No. 9). In this case, if the amount of the hole transporting material dispersed in the film is small, the hole transporting property is insufficient. Conversely, if the ratio is increased, the film acts like a plasticizer to act as a plasticizer, thereby improving the durability and thermal properties of the entire film. And the hole transport material may aggregate and crystallize. Further, it is also required to ensure the compatibility between the binder and the hole transport material, and the restriction on the material increases, which is practically difficult.

As described above, the method of dispersing the hole transport material in the organic binder has not yet achieved sufficient characteristics. Further, in the conventional organic electroluminescent device, it is also important to suppress a rise in driving voltage, and for that purpose, a contact between the anode and the hole transport layer is important. Therefore, in order to improve the contact between the anode and the hole transport layer,
It has been proposed to provide a hole injection layer between both layers.
The conditions required for the material used for the hole injection layer are that a uniform thin film can be formed with good contact with the anode, and that the material is thermally stable, that is, the melting point and the glass transition temperature are high. In addition, the ionization potential is low, holes can be easily injected from the anode, and the hole mobility is high.

Various materials have been studied as such materials, for example, porphyrin derivatives and phthalocyanine compounds (JP-A-63-295695) and star-bust type aromatic triamines (JP-A-4-308688). , Polythienylenevinylene, poly-p-phenylenevinylene (JP-A-4-145192), polyaniline (Appl. Phys.Let)
t., vol. 64, p. 1245, 1994), sputtered carbon films (JP-A-8-31573), and metal oxides such as vanadium oxide, ruthenium oxide and molybdenum oxide. The 43rd Lecture Meeting on Applied Physics, 27a-
SY-9, 1996).

However, when a porphyrin derivative or a phthalocyanine compound is used as a hole injecting layer, the light absorption of these films themselves changes the emission spectrum of the device, or the device becomes colored in appearance and becomes invisible. There is a problem. Star-bust type aromatic triamines have the advantage of low ionization potential and good transparency, but have poor heat resistance due to low glass transition point and melting point, have poor stability to local heating during continuous driving, and have reduced brightness. And voltage rise becomes a problem.

Conjugated polymers, such as polythienylenevinylene, poly-p-phenylenevinylene, and polyaniline, have a problem in the production process due to insufficient solubility. In order to improve the above-mentioned problem, it is disclosed that low-voltage driving is possible by forming a hole injection layer using a mixture of a hole transporting polymer and an electron accepting compound (Japanese Patent Application Laid-Open (JP-A) no. 2000-36390). However, in this method, since the hole injection layer is formed by spin coating or dip coating, a film is formed also on the electrode extraction terminal portion. Therefore, there is a problem in forming a contact with an external circuit in an actual panel manufacturing process.

It is also disclosed that a hole injection layer composed of a low-molecular hole transporting material and an electron accepting compound is formed by a vacuum evaporation method (Japanese Patent Application Laid-Open No. 11-251067). There are adverse effects such as thermal decomposition of the compound and corrosion of the inside of the vacuum evaporation apparatus.

[0021]

For the above reasons, the organic electroluminescent device has a serious problem in improving the color purity and the stability of the device for practical use.
The high voltage at the time of driving the organic electroluminescent device, and the unstable stability and light emission characteristics including heat resistance are major problems for light sources such as facsimile machines, copiers, and backlights of liquid crystal displays. Low purity is an undesirable characteristic for a display device such as a full-color display. This is particularly serious when considering the application to in-vehicle displays.

In view of the above situation, the present inventor has conducted intensive studies. As a result, by using a conductive resin layer and adjusting the thickness of the layer, each of the colors can be obtained without increasing the driving voltage of the element. In addition, they have found that an element having a maximum light interference effect can be formed. Further, it has been found that a polymer having both a photosensitive group and an electron-donating group in the same molecule has excellent thermal characteristics, durability, and hole transportability, and by using this polymer, It has been found that the adjustment can be easily performed, and the above-mentioned problem relating to the stability of the element can be solved. Thus, the present invention has been completed.

[0023]

That is, the gist of the present invention is that a substrate has two or more minimum light-emitting units showing different light-emitting colors, and each minimum light-emitting unit is provided between at least an anode and a cathode. , Has a laminated structure having a light emitting layer and optional layers as needed, the light emitting layer or any layer,
An organic electroluminescent device, wherein the resin layer is formed using a photosensitive composition, and the thickness of the resin layer is different between minimum emission units that emit different colors.

The gist of the present invention is an organic electroluminescent device having at least an anode, a cathode, and a resin layer on a substrate, wherein the resin layer is patterned using a photosensitive composition. The composition has a photosensitive group in a side chain,
And an organic electroluminescent device comprising a photosensitive polymer having a charge transporting group in a main chain or a side chain.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention effectively improves the color purity of each minimum light emitting unit by adjusting the thickness of a resin layer provided in an element. Now, an organic electroluminescent device having a light emitting layer formed of an aluminum complex of 8-hydroxyquinoline, which is typically used in an organic electroluminescent device, and having the structure shown in FIG. As shown in FIG.

The film thickness of ITO is 100 nm, and the wavelength is 52 nm.
When the interference effect with respect to 0 nm is maximized, the thickness of the hole transport layer becomes 180 nm. Normally, in a device in which the light interference effect is not considered, the thickness of the hole transport layer is about 70 nm. FIG. 3 shows emission spectra of the devices having the hole transport layers having different thicknesses. In the device in which the film thickness is optimized in consideration of the interference effect, the light emitting portion on the long wavelength side is reduced and the half width of the spectrum is narrower than the device in which the film thickness is not optimized. The values of the CIE chromaticity coordinates are (0.347, 0.536) for a device having a hole transport layer having a thickness of 70 nm, while (0.310, 0.56) for a device having a hole transport layer having a thickness of 180 nm.
2), which has been improved from the yellow-green region to the green region.

In principle, it is possible to apply the method using the light interference effect to red light emission or blue light emission.
It can be said that this is an effective method for realizing a full-color display. Here, the case where the minimum emission units of three colors of RGB are provided is described as an example. However, if the organic electroluminescent element has the minimum emission units of two or more colors on the same substrate,
The effects of the present invention can be utilized. The color may be other than RGB, of course.

Incidentally, the resistivity of general organic compounds (low molecular weight and high molecular weight) is about 10 ⁹ to 10 ¹² Ω · cm. When the resin layer of the present invention is formed using such a material, if the layer is thick, the driving voltage of the element may increase as described above. Therefore, the resistivity of the resin layer is 10 ⁴ to
It is preferably about 10 ⁸ Ω · cm. Such an organic electroluminescent element has a photosensitive group in a side chain, and is easily prepared by using a photosensitive composition containing a photosensitive polymer having a charge transporting group in a main chain or a side chain. Can be manufactured.

For example, 1) a step of applying a photosensitive composition, 2) a step of irradiating a coating film with light through a photomask for forming a minimum emission unit (exposure step), and 3) a development step of removing an uncured portion. Is repeated to form a resin layer sequentially for the minimum emission unit of each color. In the application step 1), by selecting the optimum film thickness for each color of the minimum light emitting unit, a resin layer having a different film thickness for each color can be formed. Specifically, for example, the concentration (viscosity) of the coating liquid and the number of rotations of the spin coater may be adjusted for each color.

As described above, the resin layer patterned for each color is sandwiched directly between the anode and the cathode or via an optional layer provided as necessary. The resin layer is used as a light emitting layer or as an optional layer provided between an anode and a cathode as needed. Of these, a structure in which the layer is provided as a light-emitting layer or as a hole-injecting / transporting layer between an anode and a light-emitting layer is preferable. A structure provided as a hole injecting / transporting layer is most preferable.

The photosensitive composition used in the present invention comprises:
A photo-curing type or a photo-solubilizing type may be used, but a photo-curing type is preferred, and the photo-curing type will be described below. The layer formed using the photocurable photosensitive composition is cured and insolubilized by photocrosslinking and the like, and improves the durability of the layer.
By removing the portion that has not been insolubilized with a solvent or the like, the layer can be patterned, and the element manufacturing process can be simplified.

The photosensitive polymer of the present invention has a charge transporting group in the same molecule, and the charge transporting group may be electron donating or electron accepting, but is usually electron donating. Hereinafter, a case having an electron donating group will be described. Since the photosensitive polymer of the present invention itself has a hole transporting property because it contains an electron donating group in the same molecule,
Unlike the case where a layer formed by dispersing an electron-donating compound in a composition containing a usual photosensitive resin (hereinafter, referred to as a film formed in a dispersion type) is used, the composition ratio depends on the film forming property. Since the ratio of the photosensitive group to the electron donating group in the composition is not limited, the hole transporting property can be kept high. Further, by including an electron-accepting compound in the same layer, the conductivity of the layer can be increased and the voltage of the element can be reduced.

That is, a photosensitive polymer having a photocrosslinkable group (photosensitive group) and a hole transporting group (electron donating group) in the same molecule is used as the resin layer forming composition of the present invention. Thereby, the two roles of the formation of the minimum light-emitting unit by pattern formation and the hole transport can be fulfilled by one material, and the characteristics can be sufficiently exhibited. Furthermore, the layer of the present invention, which is formed using the photosensitive composition and obtained by patterning by light irradiation, does not require a solvent. Therefore, a layer can be formed on the layer by a coating method using a solvent. Since a layer containing a low molecular compound as a main component is soluble in a solvent, it was not possible to stack one or more layers on an electrode and a layer containing a high molecular compound as a main component. However, in the case of the organic electroluminescent device of the present invention, a polymer layer can be further formed on the resin layer formed using the photosensitive composition. It is also possible to use layers. Therefore, the range of choice of the material of the organic electroluminescent element is widened, and the degree of freedom in element design is increased, which is preferable.

As the photosensitive group in the photosensitive polymer of the present invention, any group may be used as long as the polymer having the photosensitive group exhibits a function of curing or solubilizing by exposure. Although not limited thereto, for example, a photosensitive group used for a photoresist or the like may be mentioned, and examples thereof include a photopolymerization type, a photodimerization type, and a photodecomposition type. Among them, a photopolymerization type, a photodimerization type, and the like are preferable because there is no gas generation or volume shrinkage. In particular, a group containing an ethylenically unsaturated double bond such as a cinnamoyl group, a cinnamylidene group, a vinyl group, and an acryloyl group is preferable.

Here, the electron-donating group refers to a group in which electrons are given to a partner by a resonance effect or an induction effect to generate holes, and the substituent constant σ in Hammett's rule tends to be σ <0. It is. On the other hand, an electron-accepting group is a group that attracts electrons from a partner and indicates a group that tends to have σ> 0. The electron donating group in the photosensitive polymer of the present invention is not limited thereto, and examples thereof include an alkyl group, an alkoxy group, and a group having a primary, secondary, or tertiary amino group. The electron donating group may be contained in the main chain of the photosensitive polymer or may be present as a side chain, but is preferably bonded to the main chain via a divalent aromatic group as a side chain. If you are. Particularly preferred is a case where a group having a primary, secondary or tertiary amino group is bonded to the main chain via a divalent aromatic group.

The main chain of the photosensitive polymer of the present invention is preferably a vinyl polymer.
Copolymers having (III) and (III) are particularly preferred.

[0037]

Embedded image

(Wherein, Ar ¹ represents a divalent aromatic group which may have a substituent, and Ar ² and Ar ³ each independently represent an aromatic group which may have a substituent. A group represented by R ^{1 to} R
⁵ each independently represents a hydrogen atom, an alkyl group which may have a substituent or an aromatic group. Y and Z each represent a direct bond or a divalent linking group. When the resin layer in the organic electroluminescent device of the present invention is used as a light-emitting layer, it may be a layer containing a fluorescent dye as necessary.

Next, the case where the layer formed using the photosensitive composition of the present invention is used as a hole injecting / transporting layer will be described. Generally, the conditions required for a layer forming material having a hole injecting / transporting property include a high hole injection efficiency from the anode and a material capable of efficiently transporting the injected holes. Is mentioned. For that purpose, the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and impurities serving as traps are unlikely to be generated during production or use. Required.

The polymerized structural units (II) and (II) of the present invention
In the photosensitive polymer having I), preferably, Ar ¹
Represents a divalent benzene ring, naphthalene ring, anthracene ring or biphenyl group which may have a substituent, wherein the substituent is a halogen atom; an alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group. An alkenyl group such as a vinyl group; an alkoxycarbonyl group having 2 to 7 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group;
An alkoxy group having 1 to 6 carbon atoms such as an ethoxy group; an aryloxy group such as a phenoxy group and a benzyloxy group; a dialkylamino group such as a diethylamino group and a diisopropylamino group. As the substituent, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is particularly preferable.

Ar ² and Ar ³ are preferably a phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a triazyl group, a pyrazyl group, a quinoxalyl group, a thienyl group or a phenyl group, each of which may independently have a substituent. A biphenyl group, wherein the substituent is a halogen atom; a methyl group;
An alkyl group having 1 to 6 carbon atoms such as an ethyl group; an alkenyl group such as a vinyl group; an alkoxycarbonyl group having 2 to 7 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group; 7 represents an aryloxy group such as a phenoxy group and a benzyloxy group; a dialkylamino group such as a diethylamino group and a diisopropylamino group; and a diarylamino group such as a diphenylamino group and a ditolylamino group.

R ¹ to R ⁵ each independently represent a hydrogen atom,
An alkyl group which may have a substituent, or an aromatic group which may have a substituent. Examples of the substituent of the alkyl group include a methoxy group or a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom. Examples of the substituent of the aromatic group include a methyl group, a methoxy group, or a fluorine atom, a chlorine atom and a bromine atom. And the like.

R ^{1 to} R ⁵ are preferably an alkyl group having 1 to 6 carbon atoms such as a hydrogen atom, a methyl group or an ethyl group; an aromatic ring group such as a phenyl group, a naphthyl group, an anthryl group or a tolyl group, It preferably represents an aryl group. Y and Z
Represents a direct bond or a divalent linking group. As the linking group, a group bonded to a —CR ₂ ＣＲCR ₃ R ₄ group by a —CO— group or a —CR ＝ CR′—group (R and R ′ are arbitrary) is conjugated between both groups. Preferred for forming a system. Specific examples of the linking group include the following groups. k represents an integer of 1 or more, preferably 1 to 4.

[0044]

Embedded image

The ratio of the (II) structure to the (III) structure in one molecule is mainly determined by the photosensitivity caused by the (II) structure and the
(III) The ratio is usually from 1: 9 to 9: 1, although it depends on the level of the hole transport property caused by the structure. General formula (II) of the present invention
And a photosensitive polymer having a polymerized structural unit represented by (III), as long as it has the polymerized structural unit, a repeating polymer derived from another radically polymerizable monomer as long as the performance of the present invention is not impaired. And may have a unit represented by the general formula (I
It may include a plurality of types of polymerized structural units corresponding to (I) and (III). In general, if the content of the repeating unit other than the (II) or (III) structure is too large, the photocurability and the hole transportability of the photosensitive polymer are reduced. Or less, preferably 20 mol% or less, more preferably 0 mol%.

The weight average molecular weight of the photosensitive polymer is not particularly limited, but is usually about 1,000 to 1,000,000.
Considering the application for in-vehicle display, the element is required to have a heat resistance of 90 ° C or more. For this reason, the photosensitive polymer of the present invention preferably has a Tg of 90 ° C. or higher. The photosensitive polymer of the present invention comprises, for example, a vinyl monomer substituted with an electron donating group and a vinyl monomer substituted with a photosensitive group, 2,2 ′.
-Azobisisobutyronitrile (AIBN), 2,2 '
It is synthesized by radical copolymerization in an organic solvent such as toluene using a known photopolymerization initiator such as -azobis (2-methylbutyronitrile).

Preferred specific examples of the polymerized structural units represented by formulas (II) and (III) are shown in Tables 1 and 2.
However, the present invention is not limited to these.

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

[0052]

[Table 6]

[0053]

[Table 7]

[0054]

[Table 8]

[0055]

[Table 9]

[0056]

[Table 10]

[0057]

[Table 11]

[0058]

[Table 12]

[0059]

[Table 13]

[0060]

[Table 14]

[0061]

[Table 15]

[0062]

[Table 16]

[0063]

[Table 17]

[0064]

[Table 18]

[0065]

[Table 19]

[0066]

[Table 20]

[0067]

[Table 21]

[0068]

[Table 22]

[0069]

[Table 23]

[0070]

[Table 24]

[0071]

[Table 25]

[0072]

[Table 26]

[0073]

[Table 27]

[0074]

[Table 28]

[0075]

[Table 29]

[0076]

[Table 30]

[0077]

[Table 31]

[0078]

[Table 32]

[0079]

[Table 33]

[0080]

[Table 34]

[0081]

[Table 35]

[0082]

[Table 36]

[0083]

[Table 37]

[0084]

[Table 38]

[0085]

[Table 39]

[0086]

[Table 40]

[0087]

[Table 41]

[0088]

[Table 42]

[0089]

[Table 43]

[0090]

[Table 44]

[0091]

[Table 45]

[0092]

[Table 46]

[0093]

[Table 47]

[0094]

[Table 48]

[0095]

[Table 49]

[0096]

[Table 50]

[0097]

[Table 51]

[0098]

[Table 52]

By using the photosensitive composition containing the photosensitive polymer, a resin layer having an effective Tg of 90 ° C. or more can be formed. Thus, a resin layer composed of an amorphous thin film that does not easily crystallize with improved heat resistance,
By using the layer as a hole injecting / transporting layer, especially in a device in which the layer is in contact with the light emitting layer, the mutual diffusion of molecules at the interface with the light emitting layer can be sufficiently suppressed even at a high temperature of 90 ° C. or more. Can be suppressed.

The photosensitive composition of the present invention may further contain an electron accepting compound. By using a mixture of a photosensitive polymer having a high Tg and an electron-accepting compound, it becomes possible to improve not only the heat resistance but also the emission characteristics of the device. That is, charge transfer occurs by mixing the electron accepting compound with the electron donating group-containing polymer,
As a result, holes serving as free carriers are generated, and the electric conductivity of the layer is increased. Since a layer having such a composition can improve the electrical connection between the organic layer and the anode, when the layer is used as a layer in contact with the anode, a so-called hole injection layer, the driving voltage decreases and the This is particularly preferable because the stability during driving is also improved.

The content of the electron accepting compound is preferably in the range of 0.1 to 50% by weight based on the weight of the photosensitive polymer. More preferably, a concentration range of 1 to 30% by weight is desirable in practical characteristics. The electron-accepting compound may be any as long as it causes charge transfer between the above-described photosensitive polymer and the above-mentioned photosensitive polymer. As a result of investigations by the present inventors, the ionization potential of the photosensitive polymer: IP (polymer) The electron affinity of the electron-accepting compound (acceptor): when two physical property values of EA (acceptor) are represented by a relational expression of IP (polymer) −EA (acceptor) ≦ 0.7 eV, the present invention It was found to be effective for the purpose.

This will be described with reference to the energy level diagram of FIG. Generally, the ionization potential and the electron affinity are determined based on the vacuum level. The ionization potential is defined as the energy required to release electrons at the HOMO (highest occupied molecular orbital) level of a substance to a vacuum level, and the electron affinity is determined by the LUMO (lowest empty molecule) of the substance at a vacuum level. Orbit) is defined as the energy that falls to a level and stabilizes.

In the present invention, the difference between the ionization potential at the HOMO level of the photosensitive polymer shown in FIG. 4 and the electron affinity at the LUMO level of the electron accepting compound is 0.7 e.
V or less. The ionization potential is directly measured by photoelectron spectroscopy, or can be obtained by correcting an electrochemically measured oxidation potential with respect to a reference electrode.
In the case of the latter method, for example, a saturated sweetfish electrode (SC
When E) is used as a reference electrode, ionization potential = oxidation potential (vs. SCE) + 4.3e
V (“Molecular Semiconductor”
actors ", Springer-Verlag, 1
985, p. 98). The electron affinity can be obtained by subtracting the optical band gap from the above-mentioned ionization potential, or similarly from the above-mentioned formula from the electrochemical reduction potential.

The relational expression between the ionization potential and the electron affinity can be expressed by using the oxidation potential and the reduction potential as follows: oxidation potential of polymer−reduction potential of acceptor ≦ 0.7 eV. IP (polymer) -EA
The lower limit of the value of (acceptor) is usually about -0.7 eV.

The electron-accepting compound in the present invention is not particularly limited as long as it satisfies the above relational formula.

[0106]

Embedded image

(Wherein X represents a halogen atom, ring A,
B and C each independently represent a phenyl group which may have a substituent. )). Specific examples of the electron accepting compound represented by the general formula (I) include the following compounds.

[0108]

Embedded image

In addition to the compounds represented by formula (I), preferred examples of the electron-accepting compound of the present invention are shown below with their abbreviations.

[0110]

Embedded image

The photosensitive composition of the present invention may be used, if necessary, in such a range that the performance of the resin layer or the photosensitive composition is not performed.
Other components such as a binder resin other than the above-described photosensitive polymer and various additives other than the electron-accepting compound may be contained. Next, the organic electroluminescent device of the present invention will be described with reference to the drawings. However, the organic electroluminescent device of the present invention is not limited to the structure (layer structure) described in the specification.

FIG. 5 is a cross-sectional view schematically showing one example of the structure of the organic electroluminescent device of the present invention. The organic electroluminescent device of the present invention is not limited to this structure. In the figure, 1 is a substrate,
2 represents an anode, 3 represents a hole injection layer, 5 represents a light emitting layer, and 7 represents a cathode. Hereinafter, the present invention will be described with reference to FIG. 1 using an element having a “resin layer” as a hole injection layer 3 as a feature of the present invention as an example.

The substrate 1 serves as a support for the organic electroluminescent element, and is made of a quartz or glass plate, a metal plate or a metal foil, a plastic film or a sheet, or the like. Particularly, a glass plate or a plate of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, and polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too low, the organic air-emitting device may be deteriorated by outside air passing through the substrate, which is not preferable. Therefore, a method of providing a dense silicon oxide film or the like on one or both sides of the synthetic resin substrate to ensure gas barrier properties is also a preferable method.

The anode 2 is provided on the substrate 1, and the anode 2 plays a role of injecting holes into the hole injection layer 3. This anode is usually made of a metal such as aluminum, gold, silver, nickel, palladium, and platinum; a metal oxide such as an oxide of indium and / or tin; a metal halide such as copper iodide; carbon black; (3-methylthiophene), conductive polymers such as polypyrrole and polyaniline. Usually, the formation of the anode 2 is often performed by a sputtering method, a vacuum evaporation method, or the like. Further, metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder are dispersed in an appropriate binder resin solution and applied onto the substrate 1. Thus, the anode 2 can be formed. Further, in the case of a conductive polymer, a thin film can be formed directly on the substrate 1 by electrolytic polymerization, or the conductive polymer can be applied on the substrate 1 to form the anode 2 (Appl. Phys. Lett. , 60, 2711, 1992
Year). The anode 2 may have a multilayer structure formed by laminating different materials. The thickness of the anode 2 depends on the required transparency. When transparency is required, it is desirable that the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness is usually 5 to 1000%.
nm, preferably about 10 to 500 nm. If opaque, the anode 2 may be as thick as the substrate 1.

On the anode 2, a hole injection layer 3 formed by using a photosensitive composition of the present invention and, if necessary, a photosensitive composition containing an electron-accepting compound is provided. When the hole injection layer is formed by a coating method, first, the photosensitive polymer and, if necessary, an electron-accepting compound, a binder resin that does not trap holes, and additives such as a coating property improving agent are mixed. And dissolving it in an appropriate solvent to prepare a photosensitive composition. This is applied on the anode 2 by a known coating method such as a spin coating method or a dip coating method, and dried. Next, the dried photosensitive composition layer is irradiated with light through a photomask using an exposure light source such as a halogen lamp. The uninsolubilized portion (uncured portion) is removed by a solvent or the like to perform patterning to obtain a desired drawing pattern (pattern formation). The patterning simplifies the device fabrication process, and the photocrosslinking cures the layer, which also helps to improve the durability of the layer.

In the device having the structure shown in FIG. 5, the thickness of the hole injection layer 3 is usually 5 to 1000 nm, preferably 10 to 500 nm.
nm. When the resin layer of the present invention is formed by a known coating method, so-called coating unevenness occurs, and it is expected that the film thickness of the resin layer is slightly different in each minimum light emission unit. However, the variation in film thickness due to coating unevenness is usually 10% or less of the set film thickness, and the difference in the film thickness in the resin layer of the present invention is much larger. That is, in the present invention, a difference is provided in the film thickness between the minimum emission units of different colors, more than the difference in film thickness between the minimum emission units of the same color.

The light emitting layer 5 is provided on the hole injection layer 3. In the device having the layer configuration of FIG.
It is formed of a compound capable of efficiently transporting electrons from the cathode toward the hole injection layer 3 between electrodes to which an electric field is applied. For that purpose, electron affinity is large,
In addition, the compound is required to be a compound having high electron mobility, and having high stability, and hardly generating impurities serving as traps during production or use.

As a material satisfying such conditions, 8
Metal complexes such as aluminum complexes of -hydroxyquinoline (JP-A-59-194393);
[h] quinoline metal complex (JP-A-6-322362),
Bisstyrylbenzene derivatives (Japanese Patent Application Laid-Open Nos. 1-245087 and 2-222484), bisstyrylarylene derivatives (Japanese Patent Application Laid-Open No. 2-247278), and metal complexes of (2-hydroxyphenyl) benzothiazole (Japanese Patent Application Laid-open No. −315983
Publication), silole derivatives and the like.

For the purpose of improving the luminous efficiency of the device and changing the luminescent color, for example, 8-
Doping of a fluorescent dye for laser such as coumarin using an aluminum complex of hydroxyquinoline as a host material (J. Appl. Phys., 65, 3610, 1989) has been carried out. It is also effective for organic electroluminescent devices. The advantages of this method are: 1) improved luminous efficiency by high-efficiency fluorescent dye, 2) variable emission wavelength by selecting fluorescent dye, 3) fluorescent dye that causes concentration quenching can be used, 4) poor thin film properties Fluorescent dyes can also be used.

This is also effective for the purpose of improving the driving life of the device. For example, using a metal complex such as an aluminum complex of 8-hydroxyquinoline as a host material, a naphthacene derivative represented by rubrene (JP-A-4-335087) and a quinacridone derivative (JP-A-5-205)
No. 70773), condensed polycyclic aromatic rings such as perylene (Japanese Patent Application Laid-Open No. 5-198377), and the like.
By doping by 10 to 10% by weight, the light emission characteristics of the device, particularly the driving stability, can be greatly improved.

The thickness of the light emitting layer 5 is usually 10 to 200 nm, preferably 30 to 100 nm. The light emitting layer 5 can also be formed by a coating method in the same manner as the hole injection layer 3, but when the low molecular compound as described above is used, a vacuum evaporation method is usually used. As a method for doping the light-emitting layer material (host material) with a fluorescent dye such as the above naphthacene derivative, quinacridone derivative, or perylene, there are a method of co-evaporation and a method of mixing an evaporation source at a predetermined concentration in advance.

The above dopants (fluorescent dyes) are usually uniformly doped in the thickness direction of the light emitting layer, but may have a concentration distribution in the thickness direction. For example, doping may be performed only near the interface with the hole injection layer, or conversely, doping may be performed near the cathode interface. When the photosensitive polymer of the present invention exhibits fluorescence, it may be used for the light emitting layer. In that case, as described above in the section of the hole injection layer 3, a photosensitive composition containing the photosensitive polymer and, if necessary, other binder resins and various additives, a fluorescent dye, and the like, After a photosensitive composition film is formed by a known coating method, this is preferably exposed and developed to form a layer. "Resin layer" which is a feature of the present invention
When is used as a light emitting layer, the preferred film thickness is different for each color, but is usually 5 to 1000 nm, preferably 10 to 500 nm.

When the resin layer is used as the light emitting layer 5,
The hole injection layer 3 may be formed using the photosensitive composition of the present invention, or may be formed using a known hole injection / transport material. A cathode 7 is provided on the light emitting layer 5. The cathode 7 plays a role of injecting electrons into the light emitting layer 5. The material used for the cathode 7 includes the anode 2
Materials used for the above.

For efficient electron injection, a metal having a low work function is preferable, and a suitable metal such as tin, magnesium, indium, calcium, aluminum and silver or an alloy thereof is used. Specific examples include a low work function alloy electrode such as a magnesium-silver alloy, a magnesium-indium alloy, and an aluminum-lithium alloy.

The cathode 7 is made of indium oxide (IT)
By using a transparent electrode such as O), light emitted from the light-emitting layer 5 can be extracted to the cathode side, and a transparent element can be formed by using a transparent electrode for both the anode and the cathode. This is preferable from the viewpoint of design and the like. The thickness of the cathode 7 is usually the same as that of the anode 2.

For the purpose of protecting the cathode made of a low work function metal, it is preferable to further laminate a metal layer having a high work function and being stable to the atmosphere, in order to increase the stability of the device. For this purpose, metals such as aluminum, silver, nickel, chromium, gold, platinum and the like are used. In the device having the configuration shown in FIG. 5, the hole injection layer has a function of receiving holes from the anode (hole injection) and a function of transporting received holes to the light emitting layer (hole transport). In addition to the function, it has a function of receiving electrons from the cathode (electron injection) and a function of transporting the received electrons to a position where they are combined with holes in the light emitting layer (electron transport). However, in order to improve the light emission characteristics of the device of the present invention, for example, as shown in FIG. 6, a hole transport layer 4 is provided between the hole injection layer 3 and the light emitting layer 5,
Furthermore, as shown in FIG. 7, it is also possible to provide a structure in which the layers are separated for each function, such as providing an electron transport layer 6 between the light emitting layer 5 and the cathode 7, that is, a function-separated element.

In the function-separated element shown in FIGS. 6 and 7,
A layer containing the photosensitive polymer of the present invention is formed as a hole injection layer 3 in the same manner as the device having the configuration of FIG. 1, and a hole transport layer 4 is separately provided between the hole injection layer 3 and the light emitting layer 5. It may be provided, or a layer containing the photosensitive polymer of the present invention may be provided as a hole transport layer 4 between the separately provided hole injection layer 3 and light emitting layer 5.

The material of the hole transport layer 4 needs to be a material that can efficiently transport the injected holes. It is more preferable that the hole injection efficiency from the hole injection layer 3 is high. For this purpose, it is required that the hole mobility is large and the stability is excellent, and that impurities serving as traps are hardly generated at the time of manufacture or use. It is more preferable that the ionization potential is smaller. In addition, since the layer is in direct contact with the light-emitting layer, it is preferable that no substance that quenches light emission be included.

As such a hole transporting material, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino]
Containing two or more tertiary amines represented by biphenyl;
Aromatic diamines in which at least two condensed aromatic rings are substituted with nitrogen atoms (JP-A-5-234681), 4,4 ', 4 "-tris (1-
Aromatic amine compounds having a starburst structure such as naphthylphenylamino) triphenylamine (J. Lumi
n., 72-74, 985, 1997), aromatic amine compounds composed of tetramers of triphenylamine (Chem. Commun., 2
175, 1996), spiro compounds such as 2,2 ', 7,7'-tetrakis- (diphenylamino) -9,9'-spirobifluorene (S
ynth. Metals, vol. 91, p. 209, 1997). These compounds may be used alone, or may be used as a mixture as necessary.

In addition to the above compounds, as a material of the hole transport layer 4, polyarylene ether sulfone (Polym. Adv) containing polyvinyl carbazole, polyvinyl triphenylamine (Japanese Patent Application Laid-Open No. 7-39553), and tetraphenylbenzidine. Tech., 7, 33, 1996). The hole transport layer 4 is formed by laminating the above material on the hole injection layer 3 by a coating method or a vacuum evaporation method.

In the case of the coating method, it can be formed in the same manner as the hole injection layer 3 described above. Examples of the binder resin include polycarbonate, polyarylate, and polyester. If the amount of the binder resin added is large, the hole mobility is lowered. Therefore, a small amount is desirable, and usually 50% by weight or less is preferable. In the case of the vacuum evaporation method, the hole transporting material is put into a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ^-4 Pa by a suitable vacuum pump, and then the crucible is heated. The hole transport material is evaporated to form the hole transport layer 4 on the substrate 1 on which the hole injection layer 3 is formed, which is placed facing the crucible.

The thickness of the hole transport layer 4 is usually 10 to 300 nm.
, Preferably 30 to 100 nm. In order to uniformly form such a thin film, generally, a vacuum deposition method is often used. As shown in FIG. 7, by further laminating the electron transport layer 6 on the light emitting layer 5, the luminous efficiency of the organic electroluminescent device can be further improved. The compound used for the electron transport layer 6 is required to be capable of easily injecting electrons from the cathode and having a higher electron transport ability.
Examples of such electron transport materials include 8-hydroxyquinoline aluminum complexes and oxadiazole derivatives (Appl. Phys. Lett., 55, 1489,
1989 and others and polymethyl methacrylate (PMM
A) A system dispersed in a resin (Appl. Phys. Lett., 61
Vol., P. 2793, 1992), phenanthroline derivatives (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinone diimine (Phys. Stat. Sol. (A)) ,14
2, p. 489, 1994), n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide, and the like.
The thickness of the electron transport layer 6 is usually 5 to 200 nm, preferably
10-100 nm.

Further, the interface between the cathode and the organic layer (the light emitting layer 5 in the structure of FIGS. 5 and 6, and the electron transport layer 6 in FIG. 7) is
Inserting an ultra-thin film (0.1 to 5 nm) of F, Li ₂ O, etc. is preferable because the efficiency of the device can be further improved (Appl. Phys. Lett., 70, 152, 1997; IE).
EE Trans. Electron. Devices, 44, 1245, 1997
Year).

It is to be noted that the structure reverse to that of FIG. 5, that is, the cathode 7, the light emitting layer 5, the hole injection layer 3, and the anode 2 can be laminated on the substrate in this order. It is also possible to provide the organic electroluminescent device of the present invention between two substrates having high transparency. Similarly, FIGS. 6 and 7
Can be stacked in the reverse order of the respective layer configurations shown in FIG.

The present specification describes Japanese Patent Application No. 2000-60.
045 (filed on March 6, 2000) and Japanese Patent Application 2000
-158072 (filed on May 29, 2000), the contents of which are incorporated in the present application.

[0136]

Next, the present invention will be described in more detail with reference to Synthesis Examples and Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. Example 1 Production examples of the polymer containing the polymerized structural unit (33) in Table 1 and the polymerized structural unit (156) in Table-2 are described below.

2-cinnamyloxyethyl methacrylate
Dissolve 1.9 g, 2.4 g of 4- (N, N-bis (4-methylphenyl)) aminophenyl methacrylate in 17 ml of dry toluene,
64 mg of 2,2′-azobis (2-methylbutyronitrile) was added as a polymerization initiator, and the mixture was polymerized at 107 ° C. for 7 hours under nitrogen. After completion of the reaction, the reaction solution was released into 150 ml of methanol, and the precipitated light gray crude product was dissolved in tetrahydrofuran, released into a large amount of methanol, reprecipitated, and purified.
8 g of a light gray powder was obtained. The yield was 43%.
The structure is shown below.

[0138]

Embedded image

The number average molecular weight of this polymer was 3,900, and the weight average molecular weight was 32,000. By 1H-NMR,
It was confirmed that the composition ratio was m: n = 1: 1. 1H-N
FIG. 8 shows the MR spectrum. Seiko Electronics DSC-20
And Tg showed a high value of 91 ° C. by differential thermal analysis. Test Example 1 The polymer obtained in Example 1 was placed on a glass substrate which had been subjected to ultrasonic cleaning with acetone, water cleaning with pure water, ultrasonic cleaning with isopropyl alcohol, drying with dry nitrogen, and UV / ozone cleaning. Spin coat under the following conditions: Solvent Chloroform Coating solution concentration 20 [mg / ml] Spinner rotation speed 1000 [rpm] Spinner rotation time 30 [sec] Drying condition Drying under nitrogen atmosphere at room temperature Transparent
A uniform thin film having a thickness of 170 nm was formed. The ionization potential of this thin film sample was measured using an ultraviolet electron analyzer (AC-1) manufactured by Riken Keiki Co., Ltd. to find that it was 5.25.
The value of eV is shown. Since the optical band gap of this polymer determined from the absorption spectrum of the thin film was 3.19 eV,
The electron affinity becomes 2.06 eV.

Next, the polymer obtained in Example 1 and the electron-accepting compound were placed on a glass substrate treated in the same manner.
A coating solution (photosensitive composition) containing TBPAH (tris (4-bromophenyl) aluminum hexachloroantimonate) was spin-coated under the following conditions: solvent chloroform 107 mg polymer of the present invention 7.4 mg TBPAH coating solution concentration 11 [mg / ml] Spinner rotation speed 2000 [rpm] Spinner rotation time 30 [seconds] Drying conditions Drying in air at room temperature By the above spin coating, uniform TBPAH with a film thickness of 40 nm is obtained.
A transparent thin film was formed in the visible light region containing 6.5% by weight.

The reduction potential of the electron accepting compound TBPAH is reported to be 1.06 eV (vs. SCE), so that the electron affinity is 5.36 eV. Therefore, the difference from the ionization potential of the aromatic amino group-containing polymer is -0.
11 eV. Test Example 2 A coating solution (photosensitive composition) containing the polymer obtained in Example 1 and coumarin 510 as a fluorescent dye was prepared and spin-coated on a glass substrate under the following conditions: Inventive polymer 49.4 mg Coumarin 510 4.4 mg Coating solution concentration 13 [mg / ml] Spinner rotation speed 500 [rpm] Spinner rotation time 60 [seconds] Drying conditions Drying in the atmosphere at room temperature By the above spin coating, coumarin 510 was 8.2% by weight. A uniform thin film having a thickness of 200 nm was formed. This thin film sample was subjected to an ultraviolet exposure apparatus (UX-10 manufactured by Ushio Inc.).
00SM), using a xenon lamp as a light source, and irradiating 3 J / cm ² light with a wavelength of 366 nm through a photomask.
Development was performed for 1 minute with a 2-propanol solution containing 20% by weight of chloroform. The pattern was formed using 2-propanol as a stop solution.

When this film was irradiated with an ultraviolet lamp of 365 nm, light emission of Coumarin 510 was observed according to the pattern of the photomask, and it was confirmed that a patterned thin film layer was formed. Example 2 Production examples of the polymer containing the polymer structural unit (5) in Table 1 and the polymer structural unit (156) in Table 2 will be described below.

2-cinnamyloxyethyl methacrylate
0.4 g, 4- (N, N-bis (4-methylphenyl)) aminostyrene 0.5 g was dissolved in 12 ml of dry toluene, and 2,2′-azobis (2-methylbutyronitrile) 31 mg was used as a polymerization initiator. In addition, polymerization was performed at 107 ° C. for 5 hours under nitrogen. After the reaction,
The reaction solution was released into 150 ml of methanol, and the precipitated light gray crude product was dissolved in tetrahydrofuran, released into a large amount of methanol, reprecipitated, and purified to obtain 0.3 g of a pale yellow powder. Yield was 22%. The structure is shown below.

[0144]

Embedded image

The number average molecular weight of this polymer was 4,200, and the weight average molecular weight was 7,200. By 1H-NMR,
It was confirmed that the composition ratio was m: n = 2.3: 1. 1H-N
FIG. 9 shows the MR spectrum. Seiko Electronics DSC-20
As a result of differential thermal analysis measurement, Tg showed a high value of 98 ° C. Test Example 3 After ultrasonic cleaning with acetone, water cleaning with pure water, ultrasonic cleaning with isopropyl alcohol, drying with dry nitrogen, and UV / ozone cleaning, the polymer obtained in Example 2 was placed on a glass substrate. Solvent Chloroform Coating solution concentration 10 [mg / ml] Spinner rotation speed 2000 [rpm] Spinner rotation time 30 [seconds] Drying conditions Drying in air at room temperature At room temperature drying by the above spin coating, a film thickness of 60 nm was obtained. A uniform thin film was formed. The thin film sample was irradiated with light having a wavelength of 366 nm at 4 J / cm ² through a photomask using a UV light exposure apparatus (UX-1000SM manufactured by Ushio Inc.) using a xenon lamp as a light source, and then chloroform was added to the sample. Development was carried out for 1 minute with a 2-propanol solution containing 1% by weight. The pattern was formed using 2-propanol as a stop solution. When this film was irradiated with an ultraviolet lamp, it was confirmed that a pattern of a photomask was formed.

Test Example 4 19 mg of the polymer obtained in Example 2 and 2 mg of TBPAH (tris (4-bromophenyl) aluminum hexachloroantimonate), which is an electron accepting compound, were added to 1,2
After dissolving in 4 ml of dichloroethane, 0.2 μm of P
The mixture was filtered through a TFE membrane filter to obtain a photosensitive composition. This is placed on a glass substrate with ITO at 1500 rpm.
And dried in dry nitrogen for 1 hour. The thickness of the dried coating film was 40 nm. On top of this, a film thickness of 80 n
An electrode was formed by evaporating a silver film of m to prepare a sample.

The voltage characteristics of the obtained sample were measured. The results are shown in FIG. Photosensitive conductivity of the resin layer formed using the composition ^{8.5 × 10 -7 Ω -1 · cm} -1, i.e. the resistivity was 1.2 × 10 ⁶ Ω · cm. Example 3 An organic electroluminescent device having the structure shown in FIG. 5 was produced by the following method.

A transparent conductive film of indium tin oxide (ITO) deposited on a glass substrate 1 with a thickness of 120 nm (manufactured by Geomatec Corporation; electron beam film-formed product; sheet resistance: 15Ω) was formed by using a usual photolithography technique and hydrochloric acid etching. 2
The anode 2 was formed by patterning into a stripe having a width of mm. The patterned ITO substrate is cleaned by ultrasonic cleaning with acetone, water cleaning with pure water, and ultrasonic cleaning with isopropyl alcohol, and then dried by nitrogen blowing.
Finally, ultraviolet ozone cleaning was performed. The polymer of the present invention obtained in Example 1 was spin-coated on the above-mentioned ITO substrate under the following conditions, and naturally dried at room temperature for 90 minutes.
A thin film having a uniform thickness of nm was formed.

Solvent Chloroform Coating solution concentration 20 [mg / ml] Spinner rotation speed 1000 [rpm] Spinner rotation time 30 [seconds] Drying conditions Nitrogen atmosphere room temperature drying (The same as in Example ² ) at ² J / cm ² and photocrosslinking to form the hole injection layer 3.

Next, the substrate on which the hole injection layer 3 is formed is evacuated.
It was installed in a vapor deposition device. The rough exhaust of the above device is
After the operation, the degree of vacuum in the device is 2x10^-6Torr (about 2.
7x10 ^-FourOil with liquid nitrogen trap until below Pa)
Evacuation was performed using a diffusion pump. Placed in the above device
Material of light emitting layer 5 put in ceramic crucible, the following structure
An 8-hydroxyquinoline complex of aluminum represented by the formula:
Al (C₉H₆NO)_Three(E-1)

[0151]

Embedded image

Was deposited. At this time of aluminum
The crucible temperature of the 8-hydroxyquinoline complex is 304-324
Control in the range of ℃, the vacuum degree during deposition is 2.3x10^-6Torr (about
3.1x10^{- Four}Pa), the deposition rate is 0.1 ~ 0.7nm / sec,
The light emitting layer had a thickness of 75 nm. The above light emitting layer 5 is vacuum
The substrate temperature during vapor deposition was kept at room temperature.

Here, the element on which the light-emitting layer 5 was deposited was once taken out of the vacuum deposition apparatus into the atmosphere, and a 2 mm-wide striped shadow mask was used as a cathode deposition mask, and the ITO stripe of the anode 2 was used. In close contact with the element so that it is perpendicular to the device, it is installed in another vacuum deposition apparatus and the degree of vacuum in the apparatus is 2x10 ^-6 Torr (about 2.7x
Evacuation was performed until the pressure became 10 ^-4 Pa) or less. Subsequently, as a cathode 7, an alloy electrode of magnesium and silver was vapor-deposited so as to have a film thickness of 44 nm by a binary simultaneous vapor deposition method. Vapor deposition was performed using a molybdenum boat, and the degree of vacuum was 1 × 10 ⁻⁵ Torr (about 1.3 × 10 ⁻³ Pa).
The deposition time was 3 minutes and 20 seconds. The atomic ratio of magnesium to silver was set to 10: 1.5. Subsequently, without breaking the vacuum of the device, the aluminum was removed using a molybdenum boat.
The cathode 7 was completed by laminating on a magnesium-silver alloy film with a thickness of 40 nm. 1.5x vacuum during aluminum deposition
10 ⁻⁵ Torr (about 2.0 × 10 ⁻³ Pa), and the deposition time was 1 minute and 20 seconds. The substrate temperature at the time of vapor deposition of the two-layered cathode of magnesium / silver alloy and aluminum was kept at room temperature.

As described above, an organic electroluminescent device having a light emitting area of 2 mm × 2 mm was obtained. Table 3 shows the characteristics of the obtained device. Reference Example 1 A device was manufactured in the same manner as in Example 3, except that photocrosslinking by exposure was not performed when forming the hole injection layer 3.
Table 3 shows the light emitting characteristics of these devices. In Table 3, the emission luminance is the value at a current density of 250 mA / cm ² , the luminous efficiency is the value at 100 cd / m ² , the luminance / current is the slope of the luminance-current density characteristic, and the voltage is 100 cd / m ² . Are shown below.

Example 4 A device was manufactured in the same manner as in Example 3, except that the polymer of the present invention obtained in Example 2 was used for the hole injection layer 3. Table 3 shows the light emission characteristics of this device. Reference Example 2 A device was produced in the same manner as in Reference Example 1, except that the polymer of the present invention obtained in Example 2 was used for the hole injection layer 3. Table 3 shows the light emission characteristics of this device.

Examples in Table 3 and Example 3 and Reference Example 1 and Examples 4 and Reference Example 2 (each having the same material and layer constitution and differing only in whether or not the photosensitive composition layer is photocrosslinked). Comparing the values of light emission luminance, light emission efficiency, and luminance / current, the device characteristics are deteriorated due to photocrosslinking of the hole injection layer 3 formed of the photosensitive composition containing the photosensitive polymer of the present invention. You can see that it is not.

[0157]

[Table 53]

Example 5 An organic electroluminescent device having the structure shown in FIG. 6 was manufactured by the following method. An indium-tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 with a thickness of 120 nm (manufactured by Geomatic Corporation; electron beam film-formed product; sheet resistance 15 Ω) was etched using a conventional photolithography technique and hydrochloric acid etching.
The anode 2 was formed by patterning into a stripe having a width of mm.

The patterned ITO substrate was washed in the order of ultrasonic cleaning with acetone, water cleaning with pure water, and ultrasonic cleaning with isopropyl alcohol, dried with nitrogen blow, and finally cleaned with ultraviolet and ozone. The mixed solution of the polymer of the present invention and TBPAH obtained in Example 1 was spin-coated on the ITO substrate under the following conditions and dried at 120 ° C. for 60 minutes to form a uniform thin film having a thickness of 60 nm. Been formed.

Solvent Chloroform Inventive polymer 107 mg TBPAH 7.4 mg Coating solution concentration 11 [mg / ml] Spinner rotation speed 2000 [rpm] Spinner rotation time 30 [seconds] Drying conditions Drying in air at room temperature At room temperature, the obtained thin film is nitrogen. Under an atmosphere, exposure was performed at 5 J / cm ² using an ultraviolet exposure apparatus (the same as in Test Example 2), and photocrosslinking was performed to form a hole injection layer 3.

Next, the substrate on which the hole injection layer 3 was formed was set in a vacuum evaporation apparatus. After the rough exhaust of the above apparatus is performed by an oil rotary pump, the degree of vacuum in the apparatus is 2 × 10 ⁻⁶ Torr (about
Evacuation was performed using an oil diffusion pump equipped with a liquid nitrogen trap until the pressure became 2.7 × 10 ⁻⁴ Pa) or less. 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (H-1) placed in a ceramic crucible placed in the above apparatus

[0162]

Embedded image

Was heated to perform vapor deposition. The degree of vacuum during the deposition was 2.8 × 10 ⁻⁶ Torr (about 3.7 × 10 ⁻⁴ Pa), and a film having a thickness of 20 nm was laminated on the hole injection layer 3 to complete the hole transport layer 4. Subsequently, the light emitting layer 5 and subsequent layers were manufactured in the same manner as in Example 3. As described above, an organic electroluminescent device having a light emitting area of 2 mm × 2 mm was obtained. Table 4 shows the emission characteristics of the obtained device.

[0164]

[Table 54]

[0165]

The organic electroluminescent device of the present invention controls the optical path length (effective use of the light interference effect) in the device by controlling the thickness of the resin layer, as compared with the case of using a low molecular weight vapor-deposited film. Is easy. Further, since the layer formed using the photosensitive composition of the present invention can easily control the film thickness independently for the minimum emission unit of each color, interference of the emission wavelength for each color is effectively caused. It can be easily designed to work.

By using a polymer containing the polymerized structural units (II) and (III) as the photosensitive polymer, the resin layer formed using the photosensitive composition containing the polymer can be subjected to a photolithography process. Even when patterning is performed, characteristics as an organic electroluminescent element are not deteriorated, and both productivity and various characteristics as an element can be achieved.
Accordingly, the organic electroluminescent device according to the present invention can be used as a flat panel display (for example, for an OA computer or a wall-mounted television) or a light source utilizing the characteristics of a surface light emitter (for example, a light source of a copier, a backlight of a liquid crystal display or an instrument). It can be applied to a light source, a display plate, and a sign lamp, and particularly has a great technical value as an in-vehicle display element requiring high heat resistance.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an optical interference effect in an organic electroluminescent device of the present invention.

FIG. 2 is a diagram showing light interference characteristics at emission wavelengths corresponding to blue, green, and red.

FIG. 3 is a diagram showing a difference in emission spectrum shape of an organic electroluminescent element depending on the presence or absence of a light interference effect.

FIG. 4 is an energy level diagram showing the relationship between ionization potential and electron affinity.

FIG. 5 is a schematic sectional view showing an example of the organic electroluminescent device of the present invention.

FIG. 6 is a schematic sectional view showing another example of the organic electroluminescent device of the present invention.

FIG. 7 is a schematic cross-sectional view showing another example of the organic electroluminescent device of the present invention.

FIG. 8 shows 1H—N of the polymer of the present invention obtained in Example 1.
MR spectrum.

FIG. 9 shows 1H—N of the polymer of the present invention obtained in Example 2.
MR spectrum.

FIG. 10 is a diagram showing voltage characteristics of a sample obtained in Test Example 4.

[Description of Signs] 1 substrate 2 anode 3 hole injection layer 4 hole transport layer 5 light emitting layer 6 electron transport layer 7 cathode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/12 H05B 33/12 B 33/14 33/14 B (72) Inventor Tomoyuki Ogata Yokohama, Kanagawa 1000 Kamoshita-cho, Aoba-ku Mitsubishi Chemical Co., Ltd. Yokohama Research Laboratory F-term (reference) BA15P BA46Q BC43P BC43Q BC44Q CA04 JA37 JA38

Claims (19)

[Claims] 1. A substrate comprising two or more minimum emission units having different emission colors on a substrate, wherein each minimum emission unit is provided between at least an anode and a cathode, a light-emitting layer and an optional layer Wherein the light-emitting layer or any layer is a resin layer formed using a photosensitive composition, and between the minimum light-emitting units showing different emission colors, the thickness of the resin layer Wherein the organic electroluminescent device is characterized in that: 2. The organic electroluminescent device according to claim 1, wherein the minimum light-emitting unit indicates a blue, green, or red light-emitting color arranged in a plane on the substrate. 3. The photosensitive composition according to claim 1, wherein the photosensitive composition contains a photosensitive polymer having a photosensitive group in a side chain and a charge transporting group in a main chain or a side chain. Or 2
The organic electroluminescent device according to claim 1. 4. The organic electroluminescent device according to claim 3, wherein the charge transporting group is an electron donating group. 5. The organic electroluminescent device according to claim 3, wherein the photosensitive group is an ethylenically unsaturated double bond. 6. The organic electroluminescent device according to claim 3, wherein the main chain of the photosensitive polymer is a vinyl polymer. 7. A method according to claim 1, wherein the photosensitive polymer is a polymer structural unit (I)
5. The method according to claim 4, wherein the method comprises the steps of (I) and (III).
7. The organic electroluminescent device according to any one of items 6 to 6. Embedded image (In the formula, Ar ¹ represents a divalent aromatic group which may have a substituent, and Ar ² and Ar ³ each independently represent an aromatic group which may have a substituent. , R ^{1 to} R ⁵ each independently represent a hydrogen atom, an alkyl group which may have a substituent,
Or an aromatic group which may have a substituent. Y and Z each represent a direct bond or a divalent linking group. ) 8. The organic electroluminescent device according to claim 4, wherein the photosensitive composition further contains an electron accepting compound. 9. The value obtained by subtracting the electron affinity of the electron-accepting compound from the ionization potential of the photosensitive polymer is 0.7.
9. The organic electroluminescent device according to claim 8, which has an eV or less. 10. The organic electroluminescent device according to claim 8, wherein the electron accepting compound is a compound represented by the following general formula (I). Embedded image (Wherein X represents a halogen atom, and rings A, B and C
Each independently represents a phenyl group which may have a substituent. ) 11. An organic electroluminescent device having at least an anode, a cathode, and a resin layer on a substrate, wherein the resin layer is patterned using a photosensitive composition, and the photosensitive composition is An organic electroluminescent device comprising a photosensitive polymer having a photosensitive group in a side chain and a charge transporting group in a main chain or a side chain. 12. The charge transporting group is an electron donating group,
The organic electroluminescent device according to claim 11. 13. The organic electroluminescent device according to claim 11, wherein the photosensitive group is an ethylenically unsaturated double bond. 14. The organic electroluminescent device according to claim 11, wherein the main chain of the photosensitive polymer is a vinyl polymer. 15. The organic electroluminescent device according to claim 12, wherein the photosensitive polymer has the following polymer structural units (II) and (III). Embedded image (In the formula, Ar ¹ represents a divalent aromatic group which may have a substituent, and Ar ² and Ar ³ each independently represent an aromatic group which may have a substituent. , R ^{1 to} R ⁵ each independently represent a hydrogen atom, an alkyl group which may have a substituent,
Or an aromatic group which may have a substituent. Y and Z each represent a direct bond or a divalent linking group. ) 16. The photosensitive composition according to claim 12, further comprising an electron accepting compound.
The organic electroluminescent device according to any one of the above. 17. The value obtained by subtracting the electron affinity of the electron-accepting compound from the ionization potential of the photosensitive polymer is 0.1.
17. The organic electroluminescent device according to claim 16, which is at most 7 eV. 18. The compound according to claim 16, wherein the electron-accepting compound is a compound represented by the following general formula (I).
The organic electroluminescent device according to claim 1. Embedded image (Wherein X represents a halogen atom, and rings A, B and C
Each independently represents a phenyl group which may have a substituent. ) 19. The following polymerized structural units (II) and (II)
A photosensitive polymer having (I). Embedded image (In the formula, Ar ¹ represents a divalent aromatic group which may have a substituent, and Ar ² and Ar ³ each independently represent an aromatic group which may have a substituent. , R ^{1 to} R ⁵ each independently represent a hydrogen atom, an alkyl group which may have a substituent,
Or an aromatic group which may have a substituent. Y and Z each represent a direct bond or a divalent linking group. )