This is the national level of U.S. Application No. PCT/JP2013/073066, filed August 28, 2013. Priority under 35 U.S.C. § 119(a) and 35 U.S.C. Section 365(b) is claimed from Japanese Order No. 2012-194037 filed on Sep. 4, 2012, the description of which is also incorporated herein by reference.
The present invention relates to an organic electroluminescence element and a lighting device and display device equipped therewith.
An organic electroluminescent element (hereinafter also referred to as an organic EL element) is a light-emitting element having a structure in which a light-emitting layer containing a light-emitting compound is sandwiched between a negative electrode and a negative electrode. whose excitons are generated in the light-emitting layer by the recombination of holes injected from a positive electrode and electrons injected from a negative electrode according to application of the electric field, and light (fluorescence or phosphorescence) is emitted , when the excitons are inactivated . Organic EL element includes any single element consisting of an organic material film which is at most a few submicrons thick between electrodes and can emit light with a voltage of several volts to several tens of volts, and hence its application as the next A flat panel display or a lighting device corresponding to the prior art is provided.
Princeton University has developed an organic EL element for practical use and has reported an organic EL element using phosphorescent light emission from a triplet excited state (see, for example, Non-Proprietary Literature 1). Materials that emit phosphorescence at room temperature have been widely studied since then (for example, see Patent Literature 1 and Non-patent Literature 2).
In addition, the achievable emission efficiency in organic EL elements using the newly discovered phosphorescent light emission is, in principle, about four times higher than that of conventional elements using fluorescent emission. Research and development of layer and electrode structures of light-emitting elements and development of materials for the elements have been carried out all over the world. For example, the synthesis of many compounds has been investigated, mainly heavy metal complexes such as iridium complexes (see, for example, Nonproprietary Literature 3).
Although organic EL devices using phosphorescent light emission as described above have considerably high potential, they have quite different technical problems from organic EL devices using fluorescent emission, i. H. controlling the position of the emission center, particularly how recombination can be. be performed within a light-emitting layer and how stable light emission can be achieved through recombination in the light-emitting layer, which is a fundamental technical challenge in determining the efficiency and lifetime of an element.
Under such circumstances, a multilayer laminate having a light-emitting layer, a hole-transporting layer adjacent to the light-emitting layer (provided on the positive electrode side of the light-emitting layer), and an electron-transporting layer adjacent to the light-emitting layer becomes. Light-emitting layer (arranged on the negative electrode side of the light-emitting layer) are well known (see Patent Literature 2, for example). For a light-emitting layer, many mixed layers containing a host compound and a phosphorescent light-emitting compound as dopants are used.
Meanwhile, regarding materials, a material that has high toughness or is thermally or electrically stable is required. In order to use blue phosphorescent luminescence in particular, since a blue phosphorescent light-emitting compound itself has high triplet excitation energy (T1), development of applicable by-materials and precise control of the light-emitting center are extremely necessary.
As a representative blue phosphorescent light-emitting compound, FIrpic is known, and the short wavelength was obtained by replacing phenylpyridinefluor as the primary linker and using picolic acid as the secondary linker. These dopants are combined with carbazole derivatives or triarylsilanes as guest compounds to form one element with high efficiency. However, since the light emission life of the element deteriorates significantly, there has been a need to improve such compensation.
Recently, Patent Publications 3 and 4 have disclosed a specific ligand-metal complex as a high potential blue phosphorescent light-emitting compound. However, although luminance efficiency and light emission lifetime have improved, the organic EL element described in these publications has improved a problem in thermal stability of a metal complex as a material of an organic EL element. Thus, due to the occurrence of decomposition products during the formation of an organic layer by deposition with this metal complex, there are cases where the service life of the element is deteriorated.
In addition, the organic EL element is also required to have long-term stability in view of its use for a display or lighting device. Regarding a light-emitting layer of an organic EL element, a state inside the light-emitting layer changes when light emission is allowed to occur continuously over a long period of time or in a high-temperature environment. Concentration quenching caused by crystallization or aggregation of light-emitting dopants, quenching caused by interaction between excitons, or the like. As a result, there may arise a problem in which the drive voltage increases or the element performance deteriorates, such as B. a decrease in the brightness of the luminance. In this regard, in Patent Literatures 3 and 4, there is no disclosure of long-term stability. Therefore, it was found that further improvement is required.
- Patented 1: US-Patent Nr. 6,097,147
- Patentliteratur 2: JP 2005-112765 A
- Patent 3: US 2011-0057559
- Patent 4: US 2011-0204333
- Non-proprietary literature 1: M.A. Baldo et al., Nature, vol. 395, pp. 151-154 (1998)
- Non-proprietary literature 2: M.A. Baldo et al., Nature, vol. 403, No. 17, pages 750 to 753 (2000)
- Non-proprietary literature 3: S. Lamansky et al., J. Am. Chemical Soc., Vol. 3, No. 123, page 4304 (2001)
As described above, various compounds related to a material of an organic EL element have been described in the prior art, and an attempt has been made to develop an organic EL element having high luminance efficiency and long lifetime. However, it has been expected to develop an organic EL element with improved thermal stability and even improved performances compared to a related art. In addition, development of an organic EL element which is also excellent in long-term stability is required.
The present invention has been conceived in view of the problems and circumstances mentioned above. The problem to be solved by the present invention is to provide an organic electroluminescent element having high luminance efficiency, long lifetime and excellent long-term stability by increasing the thermal stability of an organometallic complex as a material of an organic electroluminescent element. , and also a lighting device and a display device using the element.
The above problems are solved by the following means of the present invention.
Claims 1. An organic electroluminescent element in which at least one organic layer containing a light-emitting layer is interposed between a positive electrode and a negative electrode, characterized in that at least one contains an organometallic complex represented by the following general formula (1) is shown the organic layer,
[Chemical Formula 1]
(Ring A, Ring B and Ring C represent a 5- or 6-membered aromatic hydrocarbon ring or an aromatic heterocycle, and Ra, Rb, Rc and Rd each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon ring group or a heterocyclic non-aromatic aromatic group and may still have a substituent group.na represents an integer from 1 to 3, nb and nc each represent an integer of 1 to 4, nd represents an integer of 1 to 2, and X and Y each represent a single bond, CR1R2, NR3, O, S or SiR4R5, R1, R2, R3, R4 and R 5 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon group ng group or a non-aromatic heterocyclic group co.
L represents one or more bidentate monoanionic ligands coordinated with M, and M represents a transition metal atom having an atomic number of 40 or more and belonging to one of Groups 8 to 10 of the Periodic Table. m and n represent an integer from 1 to 2, and m+n is 2 or 3. In no case, however, are the structures of the three ligands coordinated to M identical to each other).
2. The electroluminescent organic element described under the item. 1, characterized in that all of the rings A, B and C of the above general formula (1) are a benzene ring.
3. The organic electroluminescent element described in the article. 1 or 2, characterized in that M in the above general formula (1) is Ir.
4. The organic electroluminescent element described in any one of the items. 1 to 3, characterized in that the above general formula (1) is an iridium complex represented by the following general formula (2).
[Chemical Formula 2]
(Ra, Rc and Rd each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent group, na represents an integer of 1 to 3, nc represents an integer of 1 to 4, nd represents an integer of 1 to 2, and X and Y each one represent a single bond, CR1R2, NR3, O, S or SiR4R5, but in no case X and Y represent a single bond, R2, R3, R4 and R5 represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, Rf and Rg are each independently an alkyl group, represent a hydrocarbon ring group or an aromatic heterocyclic group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, m and n represent an integer of 1 to 2 and m+n is 3. However, in no case are the structures of three ligands with Ir coordinates are identical).
5. The organic electroluminescent element described in any one of the items. 1 to 4, characterized in that Y in the above general formula (1) or (2) is a single bond.
6. The organic electroluminescent element described in any one of the items. 1 to 5, characterized in that X is O in the above general formula (1) or (2).
7. The organic electroluminescent element described in one of the articles. 1 to 6, characterized by m = 1 in the above general formula (1) or (2).
8. The organic electroluminescent element described in one of the articles. 1 to 7, characterized by emitting white light.
9. A lighting device equipped with the organic electroluminescence element according to any one of the items. 1 to 8
10. A display device equipped with the organic electroluminescent element according to any one of the articles. 1 to 8
According to the above-mentioned means of the present invention, it is possible to provide an organic electroluminescence element, particularly a white organic electroluminescence element, excellent in thermal stability, high luminance efficiency, long lifetime and excellent long-term stability. Furthermore, it is also possible to provide an illumination device and a display device with the element.
COWARDLY. 1 is a schematic diagram illustrating an example of a display device composed of an organic EL element.
COWARDLY. FIG. 2 is a schematic diagram of part A of the screen in FIG. 1. FIG. 1.
COWARDLY. 3 is a schematic diagram of a pixel.
COWARDLY. FIG. 4 is a schematic diagram of a passive color matrix type display device related to the display part A in FIG. 1. FIG. two.
COWARDLY. 5 is an outline of a lighting device.
COWARDLY. 6 is a cross-sectional view of a lighting device.
PAY. 7A - 7E are summary diagrams illustrating the construction of a full-color organic EL display device.
An embodiment for carrying out the present invention will be described in detail below. However, it is clear that the present invention is not limited thereto.
«Constitutional layers of the organic element EL»
Descriptions are given of the constituent layers of the organic EL element of the present invention. With respect to the organic EL element of the present invention, specific examples of preferable lamination of a plurality of organic layers sandwiched between a positive electrode and a negative electrode will be described below. However, the present invention is not limited to this.
(i) Positive electrode/light emitting layer/electron transport layer/negative electrode unit
(ii) Positive electrode/hole transport layer/light emitting layer unit/electron transport layer/negative electrode
(iii) Positive electrode/hole transporting layer/light emitting layer unit/hole blocking layer/electron transporting layer/negative electrode
(iv) Positive electrode/hole transport layer/luminescent layer unit/electron transport layer/electron injection layer/negative electrode
(v) Positive electrode/hole injection layer/hole transport layer/light emitting layer unit/electron transport layer/electron injection layer/negative electrode
(vi) Positive electrode/hole transport layer/light emitting layer unit/hole blocking layer/electron transport layer/electron injection layer/negative electrode
(vii) Positive electrode/hole injection layer/hole transport layer/light emitting layer unit/hole blocking layer/electron transport layer/electron injection layer/negative electrode
As the blocking layer, an electron blocking layer can also be used in addition to a hole blocking layer.
The unit light-emitting layer (hereinafter simply referred to as light-emitting layer) may consist of a single light-emitting layer or multiple light-emitting layers. Furthermore, the unit light-emitting layer may have an intermediate layer having a non-luminescent property among different light-emitting layers. It is also possible that the intermediate layer has a multiphoton unit structure like a charge generation layer. In this case, examples of the charge generation layer include a conductive inorganic compound layer such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), ZnO2, TiN, ZrN, HfN, TiOX, VOX, CuI, InN, GaN, CuAlO2, CuGaO2, Herz2Ö2, Labor6, from RuO2, a bilayer film as Au/Bi2Ö3, a multilayer film like SnO2/Ag/SnO2, ZnO/Ag/ZnO, Bi2Ö3/Au/Bi2Ö3, TiO2/TiN/TiO2, the uncle2/ZrN/TiO2B. fullerenes such as C60, a conductive organic layer such as oligotiophen and a conductive layer of an organic compound such as metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, metal-free porphyrins.
The light-emitting layer of an organic EL element of the present invention is preferably a white light-emitting layer, and preferably a lighting device or a display device using the same. That is, the organic EL element emits white light.
Descriptions are given below of each layer constituting the organic EL element of the present invention.
"Light Emitting Layer"
The light-emitting layer is a layer that emits light by recombination of electrons and holes injected from electrodes or an electron transport layer and a hole transport layer. The light emitting site may be within the light emitting layer or may be the interface between the light emitting layer and an adjacent layer thereof.
The light-emitting layer may have any total film thickness preferably controlled within a range of 2 nm to 5 µm, more preferably 2 nm to 200 nm, and most preferably 5 nm to 100 nm in view of obtaining homogeneity of the film , avoiding the application of an unnecessarily high voltage during the emission of light and improving the stability of the emission color against the driving current.
The light-emitting layer can be prepared by forming a film of a luminescent dopant or a guest compound described below, for example, by vacuum deposition or a wet process (also known as a wet process, and examples thereof include spin coating, casting, spray coating). film coating, roll coating, ink jet printing, spray coating, curtain coating, LB deposition method (Langmuir-Blodgett method) or the like). On the other hand, when the organometallic complex according to the present invention is used as a material for a light-emitting layer, the film is preferably formed by a wet process.
The light-emitting layer of the organic EL element of the present invention preferably contains a luminescent dopant (a phosphorescent light-emitting dopant (also referred to as a phosphorescent dopant or a phosphorescent light-emitting dopant group) or a fluorescent dopant) and a luminescent compound dopant guest.
(1) Luminescent doping compound
The luminescent dopant compound (also referred to as luminescent dopant, dopant compound, or simply dopant) is described below.
As the luminescent dopant, a fluorescent dopant (also called a fluorescent compound) or a phosphorescent dopant (also called a phosphorescent light-emitting material compound, a phosphorescent compound, or a phosphorescent light-emitting compound) can be used.
(1.1) Phosphorescent dopant (aka phosphorescent light-emitting dopant)
A phosphorescent dopant that can be used for the present invention is described below.
The phosphorescent dopant compound that can be used in the present invention is a compound in which light emission is observed from the excited triplet, namely a compound that emits phosphorescence at room temperature (25°C), and is defined as a compound having a give a quantum phosphorescence of 0.01 or more at 25°C. The phosphorescence quantum yield is preferably 0.1 or more.
The phosphorescence quantum yield can be measured by the method described on page 398 of Spectroscopy II of Lectures of Experimental Chemistry 7, Fourth Edition (1992 Edition, published by Maruzen Company, Limited). The quantum yield of phosphorescence in a solution can be measured using different solvents. The only requirement for the phosphorescent dopant that can be used in the present invention is to achieve the aforementioned phosphorescence quantum yield (0.01 or more) in any of the solvents.
There are two principles for the emission of a phosphorescent dopant. One is of the energy transfer type in which recombination of the carriers occurs in a host compound to which the carriers are transferred to produce an excited state of the luminescent host compound and then light is emitted from the phosphorescent dopant which transfers that energy to a phosphorescent one Connection. Dopant The other is a kind of carrier trap in which a phosphorescent dopant serves as a carrier trap to cause recombination of carriers in the phosphorescent dopant, and thus light emission from the phosphorescent dopant occurs. In any case, it is essential that the energy in the excited state of the phosphorescent dopant is lower than that in the excited state of the host compound.
In this regard, the inventors of the present invention have made intensive studies in order to achieve the above-mentioned object of the present invention. As a result, they found that enclosing an organometallic complex represented by the following general formula (1) in an organic layer of an organic EL device increases the thermal stability of the organic EL device. They also found that luminance, light emission lifetime and long-term stability were improved.
That is, according to the organic EL element of the present invention, an organometallic complex represented by the following general formula (1) is contained as a material of an organic EL element in at least one organic layer. It is preferable that an iridium complex compound represented by the following general formula (1) is contained as an organic EL element material in a light-emitting layer between the organic layers.
(1.1.1) Organometallic complex represented by general formula (1)
Descriptions are given of the organometallic complex contained as the material of the organic EL element in the organic EL element of the present invention. The organometallic complex of the present invention is represented by the following general formula (1).
[Chemical Formula 3]
In the general formula (1), Ring A, Ring B and Ring C represent a 5- or 6-membered aromatic hydrocarbon ring or an aromatic heterocycle.
Examples of the 5- or 6-membered aromatic hydrocarbon ring represented by Ring A, Ring B and Ring C in the general formula (1) include a benzene ring.
In the general formula (1), examples of the 5- or 6-membered heteroaromatic hydrocarbon ring represented by A ring, B ring and C ring include furan ring, thiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring , pyrimidine ring, pyrazine ring, triazine ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole and a thiazole ring.
Preferably, all of Ring A, Ring B and Ring C is a benzene ring.
In the general formula (1), Ra, Rb, Rc and Rd each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino, a a silyl group, an arylalkyl group, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent group. Preferably they are an alkyl group.
Examples of the alkyl group represented by Ra, Rb, Rc and Rd in the general formula (1) include methyl group, ethyl group, trifluoromethyl group, n-propyl group, isopropyl group, n-butyl group and t-butyl group. a 1-ethylpropyl group, a 2-methylhexyl group, a pentyl group, an inflexible group, an n-decyl group and an n-dodecyl group.
Examples of the aryl group and heteroaryl group represented by Ra, Rb, Rc and Rd in the general formula (1) include a monovalent group derived from an aromatic hydrocarbon ring and an aromatic heterocycle.
Examples of the aromatic hydrocarbon ring include benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, pentacene ring, perylene ring , pentaphene ring, picene ring, pyranthrene ring and an anthropopene ring.
Examples of the aromatic heterocycle include silole ring, furan ring, thiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, a quinoxaline ring, a quinazoline ring A phthalazine ring, a thienotiophen ring, a carbazole, an azacarbazole ring (refers to a carbazole ring in which one or more carbon atoms have replaced the carbazole ring with a nitrogen atom), a dibenzosilole ring, a dibenzofuran ring, a dibenzothiophene ring, a dibenzofuran ring, or a benzothiophene ring in which a or more carbon atoms form the dibenzofuran ring or or benzothiophene through a nitrogen atom, benzodifuran ring, benzodithiophene ring, acridine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, quindoline ring, thebenidine ring, quinindoline ring, triphenodithiaz in ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, an antrafuran ring, an antradifuran ring, an anthrathiophene ring, an anthrathiophene ring, a thianthrene ring, a phenoxathiine ring, a dibenzocarbazole ring, an indolocarbazole ring, and a dithienobenzene ring.
Examples of the non-aromatic hydrocarbon ring represented by Ra, Rb, Rc and Rd in the general formula (1) include a cycloalkane (e.g. a cyclopentane ring and a cyclohexane ring), a cycloalkoxy group (e.g. a cyclopentyloxy group and a cyclohexyloxy group), a cycloalkylthio group ( e.g., a cyclopentylthio group and a cyclohexylthio group), a cyclohexylaminosulfonyl group, a tetrahydronaphthalene ring, a 9,10-dihydroanthracene ring and a biphenylene ring.
Examples of the non-aromatic heterocycle represented by Ra, Rb, Rc and Rd in the general formula (1) include epoxy ring, aziridine ring, tyrant ring, oxetane ring, azetidine ring, thiethane ring, tetrahydrofuran ring, dioxolane ring, pyrrolidine ring, pyrazolidine ring, imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring , sulfolane ring, thiazolidine ring, ε-caprolactone ring, ε-caprolactam ring, piperidine ring, a hexahydropyridazine ring, a hexahydropyrimidine, a piperazine ring, a morpholine ring, a tetrahydropyran ring, a 1,3-dioxane ring, a 1,4-dioxane ring, a trioxane ring, a tetrahydrothiopyran , a thiomorpholine ring, a thiomorpholine-1,1-dioxide ring, a pyranose ring, a diazabicyclo[2,2,2]octane ring, a phenoxazine ring, a phenothiazine ring, an oxanthrene, a thioxane ring no and a phenoxatine ring.
In the general formula (1), the rings represented by Ra, Rb, Rc, and Rd may have a substituent group, or the substituent groups may bond to each other to form a ring.
In the general formula (1), na represents an integer of 1 to 3, nb and nc each represents an integer of 1 to 4, and nd represents an integer of 1 to 2.
In the general formula (1), X and Y each represent a single bond, CR1R2, NR3, O, S and SiR4R5. R1, R2, R3, R4 and R5 represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group.
In the general formula (1), L represents one or more of the monoanionic bidentate ligands coordinated with M, and M represents a transition metal atom having an atomic number of 40 or more and belongs to any one of Groups 8 to 10 of the general formula (1 ) periodic table.
In the general formula (1), m and n represent an integer of 1 to 2, and m+n is 2 or 3.
Meanwhile, in the general formula (1), in no case are the structures of the three ligands coordinating to M identical to each other.
In the general formula (1), M is preferably Ir.
(1.1.2) Organometallic complex represented by general formula (2)
The organometallic complex represented by the general formula (1) described above is preferably an iridium complex represented by the following general formula (2).
[Chemical Formula 4]
In the general formula (2), Ra, Rc, Rd, na, nc, nd, X and Y have the same meanings as Ra, Rc, Rd, na, nc, nd, X and Y in the general formula (1). However, X and Y are in no case a single bond.
In the general formula (2), Re, Rf and Rg each independently represent an alkyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group.
As an alkyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group in the general formula (2), a monovalent group derived from an alkyl group, there may be an aromatic hydrocarbon ring group, an aromatic heterocyclic group , a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group represented by Ra, Rb, Rc and Rd in the general formula (1).
In the general formula (2), m and n represent an integer of 1 to 2, and m+n is 3.
In no case, however, are the structures of the three Ir-coordinated ligands in general formula (2) identical.
In the general formula (1) or (2), Y is preferably a single bond and X is preferably O. It is also preferred that m=1.
(1.1.3) Specific examples
Specific examples of the organometallic complex represented by the general formulas (1), (2) are described below. However, the present invention is not limited to this.
Synthesis examples of a compound represented by general formula (1), (2) are described below. However, the present invention is not limited to this. Among the specific examples, the synthesis method for DP-1 is described below as an example.
DP-1 can be synthesized according to the following scheme.
In a 100 ml four-necked flask are placed 1.65 g of Intermediate A, 13 ml of 2-ethoxyethanol and 3 ml of water. After attaching a nitrogen inlet, thermometer and condenser, it was placed in an oil bath shaker. Then 0.55 g IrCl3.3H2They were added thereto and refluxed for 6 hours at an internal temperature of 135°C or higher under a stream of nitrogen until the reaction was completed.
After completion of the reaction, it was cooled to room temperature and methanol was added, followed by filtration and collection of precipitated solids. The solids obtained were washed well with methanol and dried to obtain Intermediate B 1.12 g (77.0%).
Into a 50 ml four-necked flask were placed 1.00 g of Intermediate B, 0.86 g of Intermediate C, 0.30 g of silver trifluoroacetate and 20 ml of phenyl acetate. After attaching a nitrogen inlet, thermometer and air cooling tube, it was placed in an oil bath shaker. Then, it was heated with stirring for 8 hours at an internal temperature of 150°C or more under a stream of nitrogen until the reaction was completed.
After completion of the reaction, it was cooled to room temperature and methanol was added to disperse, followed by filtration and collecting 1.06 g of crude crystals.
The crystals were purified by column chromatography (developing solvent: tetrahydrofuran/heptane). Next, the obtained crystals were heated and suspended in a mixed solvent of tetrahydrofuran and ethyl acetate, followed by filtration to obtain 0.93 g (66.6%) of DP-1. The structure of the DP-1 compound was determined by mass spectra and1H-RMN.
Mass spectrum (ESI): m/z=1193 [M+]
1H-RMN (THF-d8, 400 MHz): δ 6,40-7,94 (29H, m), δ 2,64-3,48 (6H, m), δ 1,19-1,87 (36H , M)
(1.2) Fluorescent dopant (aka fluorescent compound)
Examples of fluorescent dopants include coumarin dye, pyran dye, cyanine dye, cloconium dye, squaryllium dye, oxobenzanthracene dye, fluorescein dye, rhodamine dye, pyrilium dye, a perylene dye, a stilbene dye , a polythiophene dye, fluorescent rare earth complexes, and a compound with high fluorescence quantum yield visualized by a laser dye.
(1.3) Combined use with conventionally known dopants
The luminescent dopant that can be used in the present invention can be used in combination with a variety of other compounds. A combination of phosphorescent dopants having different structures or a combination of a phosphorescent dopant and a fluorescent dopant can also be used.
Here, for a luminescent dopant, specific examples of a conventionally known luminescent dopant that can be used in combination with the organometallic complex represented by the general formula (1) according to the present invention are given. However, the present invention is not limited to this.
(2) Luminescent guest compound (also called luminescent guest or guest compound)
The guest compound in the present invention is defined as a compound which is contained in the light-emitting layer in an amount of 20% by mass or more based on the layer and which has a quantum yield of light-emitting phosphorescence of less than phosphorescent 0 .1, preferably less than 0.01, at room temperature (25°C). Furthermore, among the compounds contained in a light-emitting layer, those having a content by mass of 50% or more in the layer are preferred.
The luminescent host that can be used in the present invention is not particularly limited, and the compound that is conventionally used for an organic EL element can be used. Typical examples include carbazole derivatives, triarylamine derivatives, aromatic derivatives, nitrogen-containing heterocyclic compounds, thiophene derivatives, furan derivatives, compounds having basic main chains of, for example, oligoarylene compounds, carboline derivatives, and diazacarbazole derivatives (here, the diazacarbazole derivative is a Compound having a nitrogen atom replaced by at least one carbon atom in the hydrocarbon ring forming the carboline ring of a carboline derivative).
The well-known luminescent host which can be used in the present invention is preferably a compound having hole transportability and electron transportability and also preventing the shift of luminescence to the longer wavelength side and high Tg (glass transition).
In addition, in the present invention, a conventionally known luminescent host can be used alone or in combination of various types. By using various kinds of luminescent hosts, it is possible to control charge migration, so that the efficiency of the organic EL element can be increased. In addition, the use of various kinds of metal complexes of the present invention and/or conventionally known compounds used as phosphorescent dopants enables mixing of different luminescences, whereby any emission color can be obtained.
The luminescent host used in the present invention can be a low-molecular compound, a high-molecular compound having a repeating unit, a low-molecular compound having a polymerizable group such as a vinyl group or an epoxy group (polymerizable luminescent host) and these compounds can be used alone, or different types of them can be used.
Specific examples of the conventionally known luminescent host include those described in the following documents.
JP 2001-257076 A, JP 2002-308855 A, JP 2001-313179 A, JP 2002-319491 A, JP 2001-357977 A, JP 2002-334786 A, JP 2002-8860 A, JP 2002-334787 A2, JP 2002-334787 A2, -15871 A, JP 2002-334788 A, JP 2002-43056 A, JP 2002-334789 A, JP 2002-75645 A, JP 2002-338579 A, JP 2002-105445 A, JP 2002 -343568 A, JP 142073-141073-2 A, JP 2002-352957 A, JP 2002-203683 A, JP 2002-363227 A, JP 2002-231453 A, JP 2003-3165 A, JP 2002-234888 A0, JP 2 -27048 A, JP 2002-255934 A, JP 2002-260861 A, JP 2002-280183 A, JP 2002-299060 A, JP 2002-302516 A, JP 2002-305083 A, JP 2002-305084 A 0 e-2JP A.
Specific examples of those used as the luminescent host of the organic EL element of the present invention are described below. However, the present invention is not limited to this.
Furthermore, compounds which are particularly preferred as the luminescent host of the light-emitting layer of an organic EL element of the present invention are the compounds represented by the following general formula (B) or general formula (E).
[Chemical Formula 30]
In the general formulas (B) and (E), Xa represents O or S, Xb, Xc, Xd and Xe each independently represents at least one hydrogen atom, a substituent group or a group represented by the following general formula (C) one of Xb, Xc, Xd and Xe represents a group represented by the following general formula (C), and in at least one of the groups represented by the following general formula (C), Ar represents a carbazolyl group.
Ar-(L4)Norte-* General Formula (C)
In the general formula (C), L4represents a divalent linking group derived from an aromatic hydrocarbon ring or an aromatic heterocycle. n represents an integer of 0 to 3, and when n is 2 or more, plural L4They can be the same or different from each other. * represents a bonding site represented by the general formula (B) or (E). Ar represents a group represented by the following general formula (D).
[Chemical Formula 31]
In the general formula (D), Xf represents N(R''), O or S, E1 to E8 represent C(R''1) is N, is R″ is R″1represent a hydrogen atom, a substituent group or a bonding site with L4in the general formula (C). * represents a binding site with L4in the general formula (C).
Regarding the compound represented by the above general formula (B), at least two of Xb, Xc, Xd and Xe are preferably represented by the general formula (C). More preferably, Xc is represented by general formula (C) and Ar in general formula (C) represents a carbazolyl group which may have a substituent group.
Described below are specific examples of the compound represented by the general formula (B) which are preferably used as the guest compound (also referred to as luminescent host) of the light-emitting layer of an organic EL device of the present invention. . However, the present invention is not limited to this.
In addition, the compound represented by the following general formula (B') is also particularly preferably used as the luminescent host of the organic EL element light-emitting layer of the present invention.
[Chemical Formula 45]
In the general formula (B'), Xa represents O or S, Xb and Xc each independently represents a substituent group or a group represented by the above general formula (C).
At least one of Xb and Xc represents a group represented by the above general formula (C), and in at least one of the groups represented by the above general formula (C), Ar represents a carbazolyl group.
Regarding the compound represented by the above general formula (B'), Ar in the general formula (C) preferably represents a carbazolyl group which may have a substituent group. More preferably, Ar in the general formula (C) may have a substituent group and also represents a carbazolyl group bonded at the N- to L-position.4of the general formula (C).
Specific examples of the compound represented by the general formula (B') which is preferably used as a host compound (also referred to as a luminescent host) of an organic EL element light-emitting layer of the present invention include OC-9, OC -11, OC -12, OC-14, OC-18, OC-29, OC-30, OC-31 and OC-32 mentioned above as specific examples of those used as the luminescent host. However, the present invention is not limited to this.
"Electron Transport Shell"
The electron transport layer consists of a material capable of transporting electrons, and the electron injection layer and the hole blocking layer are also contained in the electron transport layer in a broad sense. The electron transport layer can have a single layer or multiple layers.
The electron transport layer may have a function of supplying injected electrons from a negative electrode to a light emitting layer. As for materials for forming an electron transport layer, any of conventionally known compounds can be selected and used in combination.
Examples of conventionally known materials used for an electron-transporting layer (hereinafter, electron-transporting material) include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrane dioxide derivatives, polycyclic aromatic hydrocarbons such as perylenenaphthalene, heterocyclic tetracarboxylic anhydride, carbodiimide, fluolenylidenemethane derivatives, anthraquinedimethane and anthrone derivatives, oxadiazole derivatives, Carboline derivatives, derivatives having a ring structure in which at least one carbon atom of the hydrocarbon ring constituting the carboline ring of carboline derivatives is replaced with a nitrogen atom, and hexaazatriphenylene derivatives.
In addition, thiadiazole derivatives in which the oxygen atoms of the oxadiazole rings of the above-mentioned oxadiazole derivatives are replaced with sulfur atoms and quinoxaline derivatives having quinoxaline rings known as electron-withdrawing groups can also be used as electron-transport materials.
Polymeric materials can also be used where these materials are incorporated into the polymer chains or where the materials are present as backbone polymer chains.
Examples of the usable electron transport material include metal complexes of 8-quinolinol derivatives such as aluminum tris(8-quinolinol)(Alk), aluminum tris(5,7-dichloro-8-quinolinol), aluminum tris(5,7-dibromo). - 8-quinolinol), aluminum tris(2-methyl-8-quinolinol), aluminum tris(5-methyl-8-quinolinol) and zinc bis(8-quinolinol) (Znq) and metal complexes in which the centers the are metals of the above metal complexes are replaced by In, Mg, Cu, Ca, Sn, Ga or Pb.
Furthermore, the usable electron transport material can be a metal-free or metal-containing phthalocyanine, or the end of which is replaced by an alkyl group or a sulfonate group, for example.
In addition, an inorganic semiconductor such as n-type Si or n-type SiC can also be used as the electron transport material.
The electron transport layer is preferably prepared by forming the electron transport material into a thin film, for example based on vacuum deposition or the wet process (also known as wet process, and examples thereof include spin coating, casting, die coating, foil coating). ). B. roll coating, ink jet, printing, spray coating, curtain coating or Langmuir-Blodgett process (LB deposition)).
The film thickness of the electron transport layer is not particularly limited. However, it is generally about 5 nm to 5000 nm, and preferably 5 nm to 200 nm. The electron transport layer may have a monolayer structure consisting of one or two or more materials mentioned above.
In addition, it can be used as a metal compound containing a metal complex and a metal halide after doping with an n-type dopant.
Described below are specific examples of the conventionally known compounds preferably used to form an electron transport layer of the organic EL element of the present invention. However, the present invention is not limited to this.
«Negative Elektrode»
As for the negative electrode, an electrode having an electrode material such as a metal having a low work function (not more than 4 eV) (referred to as an electron injecting metal), an electroconductive alloy or compound, or a mixture thereof. Specific examples of electrode materials include sodium, sodium-potassium alloys, magnesium, lithium, mixed magnesium-copper, mixed magnesium-silver, mixed magnesium-aluminum, mixed magnesium-indium, a mixture of aluminum and alumina (Al2Ö3), indium, a mixture of lithium and aluminum, and rare earth metals. Among these, in terms of electron injectability and oxidation resistance, are mixtures of an electron injector metal and a second metal that have a higher work function than the electron injector metal and are stable, such as mixtures of magnesium and silver. , mixtures of magnesium and aluminum, mixtures of magnesium and indium, mixtures of aluminum and aluminum oxide (Al2Ö3), mixtures of lithium and aluminum and aluminum.
The negative electrode can be manufactured by forming a thin film of the electrode material by a method such as metal plating or sputtering. In addition, the negative electrode preferably has a sheet resistance of several hundreds Ω/□ or less and a thickness in the range of generally 10 nm to 5 µm, and preferably 50 nm to 200 nm.
When the positive electrode or the negative electrode of the organic EL element is transparent or semi-transparent to transmit the emitted light, the luminance of the light emission is improved, and hence it is desirable.
A transparent or semi-transparent negative electrode can be prepared by forming a film of 1 nm to 20 nm in thickness from the above-mentioned metal and then forming a layer of a transparent electroconductive material, which is exemplified below for the description of the positive Electrode specified is the metal foil. . . This method can be used to produce an element having a transparent positive electrode and a transparent negative electrode.
"Injection Layer: Hole Injection Layer (Positive Electrode Buffer Layer), Electron Injection Layer (Negative Electrode Buffer Layer)"
The injection layer is a layer that is formed as needed and includes a hole injection layer and an electron injection layer. The electron injecting layer may be present between the positive electrode and the hole transporting layer or between the negative electrode and the electron transporting layer as shown in the lamination described above. Alternatively, it may be present between the positive electrode and the light-emitting layer, or between the negative electrode and the light-emitting layer.
The injection layer is provided between the electrode and an organic layer to lower driving voltage or improve luminance, and is detailed in "Electrode Material", Div. 2 Chapter 2 (pages 123 to 166) of Organic EL element and its frontier of industrialization (published by N.T.S Corporation, November 30, 1998). It comprises a hole injection layer (positive electrode buffer layer) or an electron injection layer (negative electrode buffer layer).
The positive electrode buffer layer (hole injection layer) is also described in detail in, for example, JP 9-45479 A, JP 9-260062 A and JP 8-288069 A, and specific examples thereof include phthalocyanine buffer layers represented by a copper phthalocyanine layer; buffer layer derived from hezaazatriphenylene described in JP 2003-519432 W or JP 2006-135145 A; oxide buffer layers represented by a vanadium oxide layer; amorphous carbon buffer layers; polymeric buffer layers containing electrically conductive polymers represented by polyaniline (emeraldine) or polythiophene; and orthometallic complex layers represented by a tris(2-phenylpyridine)iridium complex layer.
The negative electrode buffer layer (electron injection layer) is also described in detail in JP 6-325871 A, JP 9-17574 A and JP 10-74586 A, for example, and the examples include metal buffer layers represented by strontium or aluminum; buffer layers of alkali metal compounds represented by lithium fluoride or potassium fluoride; alkaline earth metal compound buffer layers represented by magnesium fluoride or cesium fluoride; and oxide buffer layers represented by alumina. The buffer layer (injection layer) is desirably an extremely thin layer and preferably has a film thickness ranging from 0.1 nm to 5 µm, although this may vary depending on the material.
« Barrier layer: hole barrier layer, electron barrier layer »
The blocking layer is optionally provided in addition to the organic thin film backbone layer as described above. The blocking layer is, for example, a hole blocking layer described in JP 11-204258 A and JP 11-204359 A and on page 237 of "Organic EL element and its frontier of industrialization" (published by N.T.S Corporation, 30.1998), for example.
The hole blocking layer functions as an electron transport layer in the broadest sense and is made of a material with extremely poor electron transport ability but hole transport ability and can increase the probability of electron-hole transport electron-hole recombination.
The structure of an electron transport layer described above can optionally be used as a hole blocking layer, if necessary.
The hole blocking layer of the organic EL element of the present invention is preferably formed together with the light emitting layer.
The hole blocking layer preferably contains a nitrogen-containing compound such as a carboline derivative, a carboline derivative, a diazacarbazole derivative (here, the diazacarbazole derivative is a compound in which at least one nitrogen atom is replaced with one of the carbon atoms). carboline ring) mentioned above as a guest compound.
In the present invention, when plural light-emitting layers emitting light of different colors are included, a light-emitting layer having the shortest maximum light-emitting wavelength (i.e., the layer having the shortest wavelength) is included between the light-emitting layers. emitting layers. preferably located closer to the positive electrode. In this case, an additional hole-blocking layer is preferably arranged between the shorter-wavelength layer and a second light-emitting layer closer to the positive electrode. Furthermore, preferably at least 50% by mass of the compounds contained in the hole blocking layer located at the position described above have an ionization potential at least 0.3 eV higher than that of the host compound contained in the layer which emits shorter wavelength light.
The ionization potential is defined by the energy required to release an electron in the highest occupied molecular orbital (HOMO) level of a compound into the vacuum level and can be determined, for example, as follows.
(1) The ionization potential can be calculated using Gaussian 98 Molecular Orbital Calculation Software (Gaussian 98, Revision A.11.4, M.J. Frisch, et al., Gaussian, Inc., Pittsburgh Pa., 2002) manufactured by Gaussian, Inc. in Den US as value (eV units conversion value) calculated by structure optimization with B3LYP/6-31G* as keyword. This calculated value is valid due to a high correlation between the calculated values determined by the method and the experimental values.
(2) The ionization potential can also be measured directly by photoelectron spectroscopy. For example, a low energy electron spectrometer "Model AC-1" manufactured by Riken Keiki Co., Ltd. or a method known as ultraviolet photoelectron spectroscopy can be suitably used.
Meanwhile, the electron blocking layer acts as a hole transport layer in the broadest sense, and is made of a material with hole transport ability but extremely low electron transport ability, and can increase the probability of recombination of transport of electrons and holes and block electrons.
The structure of a hole transport layer described below can optionally be used as the electron blocking layer. The hole blocking layer and the electron blocking layer according to the present invention each preferably has a film thickness of 3 nm to 100 nm, and more preferably 5 nm to 30 nm.
"Loch transport shift"
The hole transport layer consists of a hole transport material having hole transport ability. The hole injection layer and the electron blocking layer are also included in the hole transport layer in a broader sense. The orifice transport layer can be formed as a single layer or as multiple layers.
The hole transport material has hole injecting, transportability, or electron blocking abilities and can be an organic material or an inorganic material. Examples of the hole transporter material include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, deamino, oxazole derivatives, styryl anthracene derivatives, fluorenone derivatives, hydrazone. Derivatives, stilbene derivatives, silazane derivatives, aniline copolymers and electrically conductive polymers/oligomers, in particular a thiophene oligomer.
Azatriphenylene derivatives, as described for example in JP 2003-519432 W or JP 2006-135145 A, can also be used as drill support materials.
As the conveying material for the hole, those described above can be used. However, a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound, are preferably used.
Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N,N,N',N'-tetraphenyl-4,4'-diaminophenyl; N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD); 2,2-bis(4-di-p-tolylaminophenyl)propane; 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane; N,N,N',N'-tetra-p-tolyl-4,4'-diaminobiphenyl; 1,1-bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane; bis(4-dimethylamino-2-methylphenyl)phenylmethane; bis(4-di-p-tolylaminophenyl)phenylmethane; N,N'-diphenyl-N,N'-di(4-methoxyphenyl)-4,4'-diaminobiphenyl; N,N,N',N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis(diphenylamino)quadriphenyl; N,N,N-tri(p-tolyl)amine; 4-(di-p-tolylamino)-4'-[4-(di-p-tolylamino)styryl]stilbene; 4-N,N-diphenylamino-(2-diphenylvinyl)benzene; 3-methoxy-4'-N,N-diphenylaminostilbenzene; N-phenylcarbazole, compounds having two molecularly condensed aromatic anions described in US Patent 5,061,569 as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD), and compounds described in JP 4-308688 A, as 4,4',4"-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (MTDATA) in which three triphenylamine units are star-linked.
Polymeric materials in which the above-mentioned compounds are introduced into the polymer chains or in which the materials are present as main polymer chains can also be used.
An inorganic compound such as p-type Si and p-type SiC can also be used as the hole-injecting material or hole-transporting material.
So-called p-type hole transport materials as described in JP 11-251067 A or in J. Huang, et al. (Applied Physics Letters, 80 (2002), p. 139) can also be used. In the present invention, these materials are preferably used from the viewpoint of obtaining a light-emitting element with higher efficiency.
The hole transport layer can be formed in the form of a thin film made of the hole transport material by a known method such as vacuum deposition, spin coating, casting, printing including ink jet or LB method.
The film thickness of the orifice transport layer is not particularly limited. However, it is usually about 5 nm to 5 µm or more, and preferably 5 nm to 200 nm. The hole-carrying layer may have a single-layer structure composed of one or more materials mentioned above.
An impurity-doped hole transport layer with high p-type properties can also be used. Examples thereof include those disclosed in, for example, JP 4-297076 A, JP 2000-196140 A and JP 2001-102175 A, and J. Appl. Phys., 95, 5773 (2004).
In the present invention, use of such a hole-carrying layer having high p-type properties is preferred since an element with lower power consumption can be manufactured.
"positive Elektrode"
The electrode material of the positive electrode of the organic EL element is preferably an electrically conductive metal, an electrically conductive alloy or compound having a high work function (not less than 4 eV), or a mixture thereof. Specific examples of the electrode material include metals such as Au, and transparent electroconductive materials such as CuI, indium tin oxide (ITO), SnO2, is ZnO.
A material like IDIXO (In2Ö3-ZnO) capable of forming an amorphous transparent electroconductive film can also be used. The positive electrode can be manufactured by forming a thin film of the electrode material by a method such as deposition or sputtering, and then shaping the film into the desired shape by photolithography. When a highly precise pattern (not less than about 100 µm) is not required, the pattern can be formed by depositing or spraying the electrode material through a mask of the desired shape.
Alternatively, where a coatable material such as an organic electrically conductive compound is used, wet film coating such as printing or coating is also available. For the extraction of light from the positive electrode, the transmittance of the positive electrode is desirably 10% or more, and the sheet resistance of the positive electrode is preferably several hundred Ω/□ or less. The thickness of the film is generally chosen in the range of 10 nm to 1000 nm, and preferably 10 nm to 200 nm, although it may vary depending on the material.
«Stützsubstrat»
The supporting substrate (hereinafter also referred to as base, substrate, base member or carrier) which can be used for the organic EL element of the present invention can be made of any material such as glass or plastic and can be transparent or opaque. . For light extraction from the side of the supporting substrate, the supporting substrate is preferably transparent. Examples of the transparent supporting substrate preferably used include glass, quartz and transparent resin films. The particularly preferred supporting substrate is a resin film capable of imparting flexibility to the organic EL element.
Examples of the resin film include films of polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyethylene; polypropylene; Cellophane; cellulose esters and their derivatives such as cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose acetate phthalate and cellulose nitrate; polyvinylidene chloride; polyvinyl alcohol; poly(ethylene vinyl alcohol); syndiotactic polystyrene; polycarbonate; a norbornene resin; polymethylpentene; polyetherketone; polyimide; polyethersulfone (PES); polyphenylene sulfide; polysulfone; polyetherimide; polyetherketonimide; Polyamide; a fluororesin; Nylon; polymethyl methacrylate); Acrylic and polyarylate and a cycloolefin resin such as ARTON (trade name, manufactured by JSR Corp.) and APEL (trade name, manufactured by Mitsui Chemicals Inc.).
On the surface of the resin film, an organic or inorganic coating film or a hybrid coating film consisting of both can be formed. The cover film is preferably a barrier film with a water vapor permeability (permeability) of 0.01 g/(m224 h) or less (at 25 ± 0.5 °C and 90 ± 2 %RH) measured by a method according to JIS K 7129-1992, and more preferably a high barrier film of 10 ml/(meter224 h atm) or less as measured by a method according to JIS K 7126-1987, and a water vapor permeability of 10−5g/(m224 hours) or less.
As the material for forming the barrier layer, any material that can block intrusion of substances such as moisture and oxygen that cause deterioration of the article can be used, and usable examples of the material include silicon oxide, silicon dioxide, and silicon nitride. In order to reduce the brittleness of the film, a barrier film having a laminated structure composed of an inorganic layer and an organic material layer is preferred. The inorganic layer and the organic material layer may be laminated in any order, and it is preferable that both layers are alternately laminated several times.
The method for forming the barrier film is not particularly limited, and examples thereof include vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam deposition, ion plating, plasma polymerization, atmospheric pressure plasma polymerization, CVD plasma, CVD laser, thermal CVD and a coating method. The most preferred method is plasma polymerization at atmospheric pressure as described in JP 2004-68143 A.
Examples of the opaque support substrate include a metal plate or film made of, for example, aluminum and stainless steel; opaque resin substrate; and ceramic substrate.
The external light removal efficiency of the organic EL element of the present invention at room temperature is preferably 1% or more, and more preferably 5% or more.
Here, the external quantum extraction efficiency (%)=(number of photons emitted from the organic EL element to the outside)/(number of electrons supplied to the organic EL element)×100.
A hue-enhancing filter such as a color filter or a color conversion filter that converts the color of the light emitted from the organic EL element into many colors using a fluorescent compound can be used in combination. In the case of using the color conversion filter, λmax of the light emitted from the organic EL element is preferably 480 nm or less.
«Production process of organic elements EL»
As an example of the method for manufacturing an organic EL element, a method for manufacturing an element consisting of positive electrode/hole injection layer (positive electrode buffer layer)/hole transport layer/light emitting layer/blocking hole layer/electron transport layer/injection layer (negative electrode buffer layer)/negative electrode layer described.
A desired electrode material such as a positive electrode material is formed into a thin film on an appropriate base so that it may have a film thickness of 1 µm or less, preferably 10 nm to 200 nm. As a result, a positive electrode is manufactured.
Then a thin film containing an organic compound, i. H. a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection shell, which are a material for an element, is formed on the positive electrode.
As a method for forming a thin film, a film can be formed by a vacuum deposition method, a wet method (also referred to as a wet process), or the like.
As for the wet method, there are spin coating, casting, die coating, blade coating, roll coating, ink jet, printing, spray coating, curtain coating and LB method. In view of the formation of a thin film with high precision and high productivity, a method showing high adaptability to a roll-to-roll system, such as die coating, roll coating, ink jet or spray coating, is preferred. A different film formation process can be applied to each layer.
Usable examples of a liquid medium for dissolving or dispersing the organic EL materials that can be used in the present invention include ketones such as methyl ethyl ketone and cyclohexanone; aliphatic acid esters such as ethyl acetate; halogenated hydrocarbons such as dichlorobenzene; aromatic hydrocarbons such as toluene, xylene, mesitylene and cyclohexylbenzene; aliphatic hydrocarbons such as cyclohexane, decalin and dodecane; and organic solvents such as DMF and DMSO.
As the dispersion method, the dispersion can be performed, for example, by ultrasonic wave scattering, high shear scattering or medium scattering.
After the formation of these layers, a negative electrode material thin film having a thickness of 1 µm or less, preferably in the range of 50 to 200 nm, is formed to provide a negative electrode for obtaining a desired organic EL. element
Alternatively, the preparation can be carried out in reverse order, i. H. in the order of electron transport layer, hole blocking layer, light emitting layer, hole transport layer, hole injection and positive electrode.
In the production of the organic EL element of the present invention, the film-forming steps from the hole injection layer to the negative electrode are preferably performed with a single air purge. Alternatively, it can be terminated mid-process and another process executed. In this case, the process is preferably carried out under a dry inert gas atmosphere.
"Siegel"
Examples of the sealing means used in the present invention include a method in which a sealing member, an electrode and a support substrate are bonded with an adhesive.
It suffices that the sealing member is arranged to cover the display area of the organic EL element, and it may be a concave plate or a flat plate. In addition, the sealing element can have any transparency and electrical insulation.
Examples of the sealing member include glass plates, polymer plates and films, and metal plates and films. Examples of the glass plate include soda-lime glass, glass containing barium, strontium, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz plate.
Examples of polymer films include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone films.
The metal plate may be made of at least one metal or alloy selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium and tantalum.
In the present invention, a polymer film or a metal film is preferably used from the viewpoint of reducing the film thickness of the element.
The polymer film preferably has an oxygen permeability of 1×10−3ml/(m224 h atm) or less as measured by a method according to JIS K 7126-1987, and a water vapor permeability of 1 × 10−3g/(m2· 24 h) or less (at 25 ± 0.5 °C and 90 ± 2 %RH) measured by a method according to JIS K 7129-1992.
The sealing member is formed into a concave shape, for example, by sandblasting or etching.
Examples of the adhesive include photocurable or thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers; moisture curable adhesives such as 2-cyanoacrylate; and thermally or chemically curable adhesives (two-liquid mixture type) such as epoxy adhesives. Examples of the adhesive include polyamide, polyester, and polyolefin hot melt adhesives; and UV curable cationic curing type epoxy resin adhesives.
However, since the organic EL element may be degraded during the heat treatment, an adhesive curable at room temperature to 80°C is preferred. A desiccant may be dispersed in the adhesive. The adhesive can be applied to the sticky part with a commercially available dispenser or by printing, such as screen printing.
It is also preferable that an inorganic or organic layer is formed as a sealing film on the outside of the electrode on the opposite side of the support substrate over the organic layer to cover the electrode and the organic layer and come into contact with the support substrate. . In this case, the sealing film can be made of any material that can block the penetration of substances such as water and oxygen that cause deterioration of the element. Usable examples of the material include silicon oxide, silicon dioxide, and silicon nitride.
In order to improve the brittleness of the film, a sealing film having a laminated structure composed of an inorganic layer and an organic material layer is preferred. The sealing film can be formed by any method, for example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, clustered ion beam deposition, ion plating, plasma polymerization, atmospheric pressure plasma polymerization, plasma CVD, laser CVD, thermal CVD, or a coating method.
The space between the sealing member and the visible part of the organic EL element is preferably filled in the form of a gas or liquid phase with an inert gas such as nitrogen or argon, or an inactive liquid such as fluorocarbon or oil. . The cavity may be in a vacuum state. Alternatively, it can be filled with a hygroscopic mass.
Examples of the hygroscopic compound include metal oxides (e.g. sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide and alumina), sulfates (e.g. sodium sulfate, calcium sulfate, magnesium cobalt sulfate), metal halides (e.g. calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide and magnesium iodide) and perchlorates (eg, barium perchlorate and magnesium perchlorate). Sulfates, metal halides and perchlorates are suitably used in the anhydride form.
"protective film, protective plate"
To increase the mechanical strength of the element, a protective film or plate can be arranged on the outside of the sealing layer or film on the organic layer on the side opposite the carrier substrate. In particular, when a sealing film is used for sealing, the mechanical strength of the sealing film is not high enough; therefore, such a protective film or plate is desirable. Usable examples of the material for the protective film or plate include glass plates, polymer plates and films, and metal plates and films exemplified as materials for sealing. The polymer film is preferred from the viewpoint of reducing the weight and thickness of the film.
"light extraction"
In general, an organic EL element is said to generate light in a layer with a higher refractive index than air (ie, about 1.7 to 2.1 refraction) and emit only about 15% to 20% of the light generated in the light-emitting layer can . This occurs because light incident on the interface between a transparent substrate and air at an angle θ larger than a critical angle is totally reflected and cannot be removed from the element, or light at the interface between the electrode or the transparent layer is totally reflected. -Emission layer and the transparent substrate and to the transparent electrode or light emission layer to escape light to the side surface of the element.
Light extraction efficiency can be improved by forming irregularities on the surface of a transparent substrate to prevent total reflection at the interface between the transparent substrate and air (US Patent No. 4,774,435); providing light condensing properties to a substrate to improve efficiency (JP 63-314795 A); forming reflection surfaces on the side surfaces of a member (JP 1-220394 A); Disposing a planar anti-reflection layer between a substrate and a luminescent material, the anti-reflection layer having a refractive index between that of the substrate and that of the luminescent material (JP 62-172691 A); arranging a planar layer between a substrate and a luminescent material, the planar layer having a lower refractive index than the substrate (JP 2001-202827 A); and forming a diffraction grating between any layer of a substrate, a transparent electrode layer and a light-emitting layer (including on the outward surface of the substrate) (JP 11-283751 A).
In the present invention, these methods can be used in combination with the organic EL element of the present invention. Specifically, the method of disposing a flat layer having a refractive index lower than that of the substrate between the substrate and the luminescent material, or the method of forming a diffraction grating between any layer of a substrate, a transparent electrode layer and a light-transmitting layer. emissive layer (even on the outward-facing surface of the substrate) can be suitably used.
The present invention can provide an article having higher luminance or excellent durability by combining these means.
By having a medium with a low refractive index with a thickness greater than the wavelength of light between a transparent electrode and a transparent substrate, the light extraction efficiency of the transparent electrode to the outside increases as the refractive index of the medium decreases.
Examples of materials for the low refractive index layer include airgel, porous silicon oxide, magnesium fluoride, and fluoropolymer layers. Since the refractive index of a transparent substrate is generally 1.5 to 1.7, the refractive index of the low-refractive-index layer is preferably 1.5 or less, and more preferably 1.35 or less.
The low-refractive-index medium desirably has a thickness twice or more the wavelength of light in the medium for the following reason. When the low-refractive-index medium has a thickness similar to the light wavelength, the electromagnetic waves emitted as evanescent waves penetrate the substrate, resulting in a reduction in the effect of the low-refractive-index layer.
The method of installing a diffraction grating at the interface where total reflection occurs or in any medium is characterized in that it can improve the effect of increasing the light extraction efficiency. In this method, a diffraction grating is embedded at the interface between any two layers or in any medium (either on the transparent substrate or on the transparent electrode) to extract light generated at the light-emitting layer, which as a result does not turn off B. Total reflection at the interface between the layers by utilizing the property of diffraction gratings that can change the direction of light to a specific direction other than refraction by Bragg diffraction, such as primary diffraction or secondary diffraction.
The diffraction grating to be introduced desirably has two-dimensional periodic refractive indices. Since light generated in a light-emitting layer is randomly emitted in all directions, a general one-dimensional diffraction grating with a periodic refractive index distribution only in the specific direction can diffract only light propagating in a specific direction and can increase the refractive index not greatly increase light extraction efficiency.
A diffraction grating having a two-dimensional refractive index distribution can diffract light propagating in all directions, resulting in an increase in light extraction efficiency.
The diffraction grating can be inserted between any two layers or in any medium (on the transparent substrate or on the transparent electrode) as described above, but it is desirable to be inserted near the light-emitting organic layer that generates light.
The period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of the light in the medium.
The diffraction grating array is preferably repeated two-dimensionally, such as. B. a square lattice shape, a triangular lattice shape or a honeycomb lattice shape.
«Light Condensation Blade»
The organic EL element of the present invention can increase luminance in a particular direction by concentrating light in that particular direction, for example, in the frontal direction with respect to the light-emitting plane of the element, thereby providing a microstructure, for example, matrix. of lenses on the light extraction side of the element substrate or by combining them with a light condensing sheet.
In an example of a microlens array, square pyramids with a side of 30 µm and an apex angle of 90 degrees are arranged two-dimensionally on the light-extracting side of the substrate. The square pyramid preferably has a side length of 10 µm to 100 µm. A side shorter than this gap causes coloring due to diffraction effect, while a side longer than this gap makes the thickness unfavorably large.
A usable light condensing sheet is practically used for an LED backlight of a liquid crystal display device. A typical example of the sheet is a gloss enhancing film (BEF) manufactured by SUMITOMO.3Limited M
For example, a prismatic sheet may have a shape with triangular bands with an apex angle of 90 degrees and a pitch of 50 μm, a round-topped shape, a shape with randomly changing steps, or other shapes.
In order to control the light emission angle of the light emitting element, a light diffusing plate or sheet can be used in combination with the light condensing sheet. For example, one manufactured by KIMOTO Co.,Ltd. manufactured diffusion film (Light-Up) can be used.
"Application"
The organic EL element of the present invention can be used as a display device, view finder or various light emitting sources. Examples of light-emitting sources include, but are not limited to, lighting devices (household lamps and car lamps), backlights for watches and liquid crystals, light sources for advertising, traffic lights and optical storage media, light sources for electrophotographic copiers, light sources for optical communication instruments and light sources for optical sensors. In particular, the organic EL element can be advantageously used as a backlight for a liquid crystal display device or as a light source.
In the organic EL element of the present invention, films are optionally patterned with a metal mask or by ink-jet printing during film formation. The pattern can be made only for the electrodes, or for the electrodes and the light-emitting layer, or for all layers of the element. Conventionally known methods can be used to manufacture the element.
The colors of the light emitted from the organic EL element of the present invention or the compounds according to the present invention are specified with the color obtained by applying the measurement results with a CS-1000 Spectral Radiation Meter (manufactured by Konica Minolta Sensing Co. ., Ltd.) for the CIE chromaticity coordinates in FIG. 4.16 on page 108 of "New Edition of the Color Science Manual" (published by the Japan Color Science Association, University of Tokyo Press, 1985).
When the organic EL element of the present invention is a white-emitting element, white means that when the forward luminance of a viewing angle of two degrees is measured by the method described above, the chromaticity in the CIE 1931 to 1000 chromaticity system cd/meter2is within a range of X = 0.33 ± 0.07 and Y = 0.33 ± 0.1.
"demo device"
Next, the display device of the present invention will be described. The display device of the present invention has the organic EL element of the present invention. The display device of the present invention may be monochromatic or multichromatic. Next, a multi-chrome display device will be described.
In the case of a multi-color display device, a shadow mask is only provided during the formation of the light-emitting layer, and the film can be formed on one side, for example, by vacuum deposition, casting, spin coating, ink or printing.
In the case of patterning only the light-emitting layer, the patterning can be performed by any method, and is preferably performed by a vacuum deposition method, an ink jet method, a spin coating method, or a printing method.
The structure of the organic EL element provided for the display device is appropriately selected from the structure of the organic EL element mentioned above.
The manufacturing method for organic EL elements is shown in an embodiment of manufacturing organic EL elements of the present invention as described above.
When a DC voltage is applied to the multichromatic display device obtained as above, luminescence can be observed by placing the positive electrode in positive (+) polarity and the negative electrode in negative (-) polarity and applying a voltage of 2 V to 40V or more. In addition, even if a reverse polarity voltage is applied, no current flows and no light emission occurs. Even when an alternating current is applied, light is emitted only in the state where the positive electrode is positive (+) and the negative electrode is negative (-). However, the alternating current to be applied may have any waveform.
The multi-chrome display can be used as a display, a screen, or multiple light-emitting sources. On the display device and monitor, color display can be achieved with three kinds of organic EL elements that emit blue, red, and green light.
Examples of the display device and the screen include televisions, personal computers, mobile devices, AV devices, teletext screens, and information screens in automobiles. Specifically, the display device can be used for displaying still images or moving images, and the driving system in the case of using the display device for displaying moving images can be a one-matrix system (passive matrix) or an active matrix system.
Examples of the light source include a household lamp, an automobile interior lamp, a backlight for clocks and liquid crystals, a light source for license plates, a traffic light and an optical storage medium, a light source for electrophotographic copiers, a light source for optical communication instruments, and a light source for optical sensors. However, the present invention is not limited to this.
Next, an example of the display device using the organic EL element of the present invention will be described with reference to the drawings.
COWARDLY. 1 is a schematic diagram illustrating an example of a display device composed of the organic EL element of the present invention. It is a schematic diagram illustrating a screen for a cellular phone, for example, for performing display of image information by light emission of the organic EL element.
the exhibition1it consists of a display part A having a plurality of pixels and a control part B which performs image scanning of the display part A based on the image information.
The control part B is electrically connected to the display part A, and sends frame signals and image data signals to the respective pixels based on the external image information. The pixels of each scanning line receive the scanning signal and sequentially emit light according to the image data signal, and the image information is displayed on the A part of the screen by the image scanning.
COWARDLY. 2 is a schematic diagram of part A of the screen.
The display section A includes a wiring section containing a plurality of scanning lines.5and data rows6, and a multitude of pixels3on a substrate. The main elements of the display part A are described below.
COWARDLY. 2 illustrates a case where the light is emitted from pixels3it is dragged in the direction indicated by the white arrow (down direction).
scan lines5and multiple data lines6in the wiring section, they each consist of an electrically conductive material. scan lines5and multiple data lines6they are arranged orthogonally to each other in a grid pattern and connected to pixels3at intersections (details not shown).
A scan signal is applied from the scan line5and then the pixels3receiving an image data signal from the data line6and emitting light according to the received image data.
Full-color display can be achieved by correctly juxtaposing light-emitting pixels in a red area, light-emitting pixels in a green area, and light-emitting pixels in a blue area on the same substrate.
Next, the process of emitting light by a pixel will be described. COWARDLY. 3 is a schematic diagram of the pixel.
The pixel contains an organic EL element.10, a switching transistor11, a conduction transistor12, and a capacitor13. A color display can be realized using an organic EL element10for multiple pixels, an organic EL element that emits red light, green light, and blue light and arranges them side by side on the same substrate.
In Fig. 3, an image data signal is applied from the controller B to the drain of the switching transistor11per data line6. Then, a wobble signal is applied from the control part B to the gate of the switching transistor11through the scan line5to turn on the switching transistor11, and the image data signal applied to the drain is transferred to the capacitor gate13and the conduction transistor12.
the condenser13charged when the image data signal is transmitted, depending on the potential of the image data signal and the driver transistor12are you connected in conduction transistor12the drain is connected to a supply line7and a source is connected to the electrode of the organic EL element10to supply a current to the organic EL element10power line7depending on the potential of the image data signal applied to the gate.
The scanning signal is transferred to the next scanning line5by sequentially sweeping through the control part B to turn off the switching transistor11. However, the condenser13maintains the charged potential of the image data signal even after the switching transistor is turned off11, and thus the conduction state of the conduction transistor12is maintained to continue light emission by the organic EL element10until the next sweep signal is applied. line transistor12is activated according to the potential of the subsequent image data signal in synchronism with the subsequent scanning signal applied by sequential scanning, resulting in luminescence by the organic EL element10.
That is, light emission by the organic EL element.10is achieved by providing a switching transistor11and a conduction transistor12serving as active elements for the organic element EL10from each of the plurality of pixels and enabling the respective organic elements EL10multiple pixels3to emit light. This light emission process is called an active matrix system.
The luminescence of the organic EL element10it may have multiple gradations in accordance with multivalued image data signals having different gradation potentials, or a predetermined on/off light intensity in accordance with a binary image data signal. The electrical potential of the capacitor.13it may be held until the subsequent sweep signal is applied, or it may be discharged just before the subsequent sweep signal is applied.
In the present invention, the luminescence is not limited to the active matrix system described above and can be activated by a passive matrix system. In the passive matrix system, light is emitted from the organic EL element in response to the data signal only while the raster signals are being scanned.
COWARDLY. FIG. 4 is a schematic diagram of a passive matrix screen, relating to screen portion A in FIG. 3. FIG. 2. In Fig. 4, a plurality of scan lines5and a plurality of image data lines6are arranged in a grid pattern so that the pixels3are located between adjacent rows.
When a scanning signal is applied to a scanning line5by sequentially scanning the pixel3connected to the activated scan line5It emits light according to the image data signal.
The passive matrix system has no active elements in the pixels.3, which leads to a reduction in manufacturing costs.
"lighting device"
Next, a lighting device of the present invention will be described. The lighting device of the present invention is equipped with the organic EL element of the present invention.
The organic EL element of the present invention having a resonance structure can be used as an organic EL element. The organic EL element having a resonator structure can be applied to a light source for an optical storage medium, a light source for an electrophotographic copier, a light source for an optical communication instrument, or a light source for an optical sensor, among others. Alternatively, it can be used for the above purposes by laser oscillation.
The organic EL element of the present invention can be used as a lamp as an illumination source or exposure light source, or can be used as a projector for projecting images or a display device for directly displaying still or moving images.
The driving system of the display device used for displaying moving images may be a simple matrix system (passive matrix) or an active matrix system. In addition, a color display device can be manufactured by using two or more organic EL elements of the present invention which emit light of different colors.
The organic EL material of the present invention can be applied as a lighting device to an organic EL element that emits substantially white light. White light is created by mixing light of different colors emitted simultaneously by multiple luminescent materials. The combination of emitted light colors can be a combination containing three peak light emission wavelengths of the three primary colors blue, green and red, or a combination containing two peak light emission wavelengths using a ratio of complementary colors such as blue and yellow or cyan and orange.
In addition, the combination of luminescent materials for obtaining multiple colors of emitted light may be a combination of multiple phosphorescent or fluorescent materials, or a combination of a fluorescent or phosphorescent material and a pigmented material that emits light as excited light using light... of the luminescent material. However, in the white-emitting organic EL element according to the present invention, mere mixing and mixing of a variety of luminescent dopants may suffice.
It suffices that a mask is provided during the formation of a light-emitting layer, a hole-transporting layer, or an electron-transporting layer to easily separate the coating through the mask. The other layers are common and do not require patterning with a mask, and an electrode film can be formed on one side by, for example, vacuum deposition, casting, spin coating, ink jet or printing. This increases productivity.
According to this method, the element itself emits white light, unlike the white light-emitting organic EL device containing light-emitting elements emitting different colors side by side in a matrix form.
Any luminescent material can be used for the light-emitting layer. For example, in a backlight of a liquid crystal display element, white light can be generated by selecting and combining appropriate metal complexes according to the present invention or known luminescent materials to match the wavelength range corresponding to the color properties. Filters (CF). .
"An embodiment of the lighting device of the present invention"
An embodiment of the lighting device using the organic EL element of the present invention will now be described.
The non-light emitting surface of the organic EL element of the present invention is covered with a glass box, and a glass substrate with a thickness of 300 µm is used as a sealing substrate. As a sealing material, a light-curing epoxy adhesive (LUXTRACK LC0629B manufactured by Toagosei Company, Limited) is applied to the periphery, and the product is placed on the negative electrode and fixed to the transparent supporting substrate, followed by curing the adhesive by irradiating ultraviolet light through the Glass substrate for sealing. Accordingly, an illumination device such as that shown in FIG. 5 and 6 are formed.
COWARDLY. 5 is an outline of a lighting device. An organic EL element101of the present invention is covered with a glass lid102(The sealing with the glass lid was performed in a glove box under a nitrogen atmosphere (an atmosphere of high-purity nitrogen gas having a purity of at least 99.999%) to avoid contact of the organic EL element101with air).
COWARDLY. 6 illustrates a cross-sectional view of the lighting device. In Fig. 6 reference number105denotes a negative electrode, reference number106denotes an organic EL layer and the reference numeral107denotes a glass substrate provided with a transparent electrode. Meanwhile, the inside of the glass lid102(see Fig. 5) is filled with nitrogen gas108and comes with a water absorber109.
Now, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.
In addition, the structures of the compounds used in the examples described below are shown below. However, other compounds are the same as those described in the specification of the present invention.
«Production of EL Organic Element 1-1»
A substrate (NA45, manufactured by NH Techno Glass Corp.) made by forming an ITO (Indium Tin Oxide) film with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm was used shaped to form a positive electrode. A transparent base substrate provided with the ITO transparent electrode was cleaned with ultrasonic waves using isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone washing for 5 minutes.
On the transparent supporting substrate, a thin film was applied by a spin coating method under conditions including 3000 rpm and 30 seconds using a solution containing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS, manufactured by H.C. STARCK GMBH). , CLEVIO P VP AI 4083) diluted to 70% with purified water. After drying at 200°C for 1 hour, the first hole transport layer was formed with a film thickness of 20 nm.
The transparent support substrate was attached to the substrate support of a commercially available vacuum deposition apparatus. One molybdenum resistance heater canister was filled with 200 mg of α-NPD as the orifice transport material, another molybdenum resistance heater canister was filled with 200 mg of OC-30 as the host compound, another molybdenum resistance heater was filled with 200 mg of ET-8 as the electron transport material , and another molybdenum resistance heating vessel was filled with 100 mg of comparative compound A as a doping compound. Then they were put into the vacuum deposition apparatus.
Then, a vacuum vessel was depressurized to 4×10−4Pa and then the heating canister containing a-NPD was heated by electrification for vapor deposition at a deposition rate of 0.1 nm/s to form the second transport layer with a film thickness of 20 nm on the transparent support of the substrate.
In addition, heating canisters containing OC-30 as host compound or Comparative Compound A as dopant compound were electrification heated to co-deposit them on the second hole injection layer at deposition rates of 0.1 nm/s and 0.006 nm/s sec to form a light-emitting layer with to form a film thickness of 40 nm.
In addition, the heating vessel containing ET-8 was heated by electrification to form vapor deposition on a light-emitting layer at a deposition rate of 0.1 nm/s to form an electron transport layer with a film thickness of 30 nm.
At this time, the temperature of the substrate at the time of vapor deposition was room temperature.
Subsequently, lithium fluoride was deposited to form a 0.5 nm thick negative electrode buffer layer, and aluminum was further deposited to form a 110 nm thick negative electrode. Consequently, the organic element EL 1-1 was thus prepared.
«Production of EL Organic Elements 1-2 to 1-10»
Organic elements EL 1-2 to 1-10 were prepared in the same manner as organic element EL 1-1 except that the host compounds and dopant compounds in the light-emitting layer were changed to the compounds described in Table 1.
"Organic EL Element Rating 1-1 to 1-10"
For the evaluation of the obtained organic EL elements 1-1 to 1-10, the non-light emitting surface of each of the organic EL elements was covered with a glass box. A glass plate having a thickness of 300 μm was used as the substrate for sealing. As a sealing material, a light-curing epoxy adhesive (LUXTRACK LC0629B manufactured by Toagosei Company Limited) was applied to the cover glass at the periphery where the cover glass and the organic EL element glass substrate contact each other. The product was placed on the negative electrode and fixed to the transparent support substrate, followed by curing the adhesive by irradiating the portion with ultraviolet light through the glass substrate to seal. Lighting devices as shown in FIG. 5 and 6 were created and evaluated in this way.
Each sample prepared as described above was evaluated as shown below. The results of the evaluation are described in Table 1.
Then, the following evaluations were carried out.
(External extraction quantum efficiency (also called simply efficiency))
The organic EL element was driven with a constant current of 2.5 mA/cm.2at room temperature (about 23°C to 25°C) to emit light and the luminance (L) [cd/m2] was measured immediately after light emission started to calculate the external extraction quantum efficiency (η).
The luminance was measured with a spectroradiometer CS-1000 (manufactured by Konica Minolta Sensing Inc.). The external extraction quantum efficiency is shown as a relative value compared to the 1-1 value of the organic EL element set to 100.
(half-life)
Each organic EL element was driven with a constant current using a current enabling an initial luminance of 1000 cd/m2, and the time required to increase the luminance to ½ (500 cd/m2) of the initial luminance was obtained and used as a half-life standard.
Meanwhile, the half-life was displayed as a relative value in comparison with the EL 1-1 value of the organic element set at 100.
(long-term stability)
After storing the organic EL element at 60°C for 24 hours, the energy efficiency before and after the storage was obtained. For each of them, the energy efficiency index was determined, which was used as a parameter for long-term stability.
Long-term stability (%) = energy efficiency after storage/energy efficiency before storage × 100
Meanwhile, using a CS-1000 spectroradiometer (manufactured by Konica Minolta Sensing Inc.), the frontal luminance and the luminance angle dependency were measured for each organic EL element. Energy efficiency with frontal luminance of 1000 cd/m²2It has been received.
(thermal stability)
Using the same vapor deposition pot (molybdenum resistance heating starting pot) for each of the organic elements EL 1-1 to 1-10, five elements having the same composition for each were prepared (e.g. element organic EL 1-1, 1-1b , 1-1c, 1-1d and 1-1e).
For each element produced first (e.g. organic EL element 1-1), the third element produced (e.g. organic EL element 1-1c) and the fifth element produced (e.g. organic EL element 1-1e) Half life was measured by the same method as above.
| TABLE 1 | |||||||
| Extern | |||||||
| extraction | |||||||
| Organic | Quantum | Bad | long term | Thermal | |||
| the element | host | Dopant | efficiency | Life | stability | stability | Comments |
| 1-1 | OC-30 | comparative | 100 | 100 | 58 | 61 | comparative |
| Connection A | Example | ||||||
| 1-2 | OC-30 | comparative | 104 | 82 | 74 | 95 | comparative |
| Connection B | Example | ||||||
| 1-3 | OC-30 | DP-1 | 120 | 357 | 96 | 101 | Gift |
| invention | |||||||
| 1-4 | OC-11 | DP-2 | 113 | 254 | 89 | 97 | Gift |
| invention | |||||||
| 1-5 | OC-29 | DP-3 | 111 | 232 | 83 | 97 | Gift |
| invention | |||||||
| 1-6 | OC-15 | DP-32 | 122 | 288 | 94 | 99 | Gift |
| invention | |||||||
| 1-7 | 1 | DP-49 | 107 | 109 | 77 | 100 | Gift |
| invention | |||||||
| 1-8 | 53 | DP-77 | 106 | 125 | 76 | 101 | Gift |
| invention | |||||||
| 1-9 | 42 | DP-85 | 105 | 113 | 75 | 100 | Gift |
| invention | |||||||
| 1-10 | 1 | DP-57 | 119 | 326 | 90 | 96 | Gift |
| invention | |||||||
As clearly shown in Table 1, each of the organic EL elements 1-3 to 1-10 of the present invention exhibits higher luminance efficiency and longer lifetime compared to the organic EL elements 1-1 and 1-2 of the comparative examples. It has also been found to improve properties of an element such as B. excellent long-term stability. Moreover, with respect to the organic EL elements 1-1 and 1-2 of the comparative examples, the first-prepared element, the third-prepared element, and the fifth-prepared element showed a gradually decreasing half-life. However, with respect to the organic elements EL 1-3 to 1-10 of the present invention, the first-produced element, the third-produced element and the fifth-produced element showed almost no decrease in half-life. Therefore, it was found that the dopant compound used in the organic EL element of the present invention has excellent thermal stability.
«Production of EL Organic Element 2-1»
A substrate (NA-45, manufactured by AvanStrate Inc.) made by forming an ITO (Indium Tin Oxide) film with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm was used shaped to form a positive electrode. A transparent base substrate provided with the ITO transparent electrode was cleaned with ultrasonic waves using isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone washing for 5 minutes.
A thin film was applied to the transparent support substrate by a spin coating method under conditions including 3000 rpm and 30 seconds using a solution containing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS, manufactured by Bayer AG, Baytron PA AI 4083) diluted to 70% with purified water. After drying at 200°C for 1 hour, the first hole transport layer was formed with a film thickness of 30 nm.
On the first support layer, a thin film was formed by the spin coating method using a solution of poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl))benzidine (ADS - 254). in chlorobenzene manufactured by American Dye Source, Inc.). After heating and drying at 150°C for 1 hour, the second orifice transport layer was formed with a film thickness of 40 nm.
In addition, a thin film was formed on the second support layer by the spin coating method using a butyl acetate solution of OC-11 as the host compound and Comparative Compound A as the dopant compound. After heating and drying at 120°C for 1 hour, a light-emitting layer having a film thickness of 30 nm was formed.
In addition, in the light-emitting layer, a thin film was formed by the spin coating method using a 1-butanol solution of ET-11 as an electron-transporting material to form an electron-transporting layer 20 mm thick. The substrate was placed in a vacuum deposition apparatus and the vacuum film pressure was reduced to 4×10−4Shovel. Subsequently, lithium fluoride was deposited to form a 1.0 nm thick electron injection layer, and aluminum was further deposited to form a 110 nm thick negative electrode. Consequently, the organic element EL 2-1 was thus prepared.
«Production of the organic element 2-2 to 2-12»
Organic EL elements 2-2 to 2-12 were prepared in the same manner as Organic EL element 2-1 except that the guest compounds and dopant compounds in the light-emitting layer were replaced with the compounds described in Table 2.
"Classification of Organic EL Elements 2-1 to 2-12"
For the evaluation of the obtained organic elements EL 2-1 to 2-12, the organic elements EL 1-1 to 1-10 of Example 1 were sealed in the same manner and after generating a sealing device illumination as shown in FIG. 5 and Fig. 6 the evaluation was carried out.
External quantum extraction efficiency, half-life and long-term stability were evaluated in the same manner as in Example 1 for each sample prepared as described above. The evaluation results are described in Table 2, of the quantum efficiency and half-life in Table 2 are described as relative values compared to the value set at 100 of the organic EL element 2-1.
| MESA 2 | ||||||
| Extern | ||||||
| extraction | ||||||
| Organic | Quantum | Bad | long term | |||
| the element | host | Dopant | efficiency | Life | stability | Comments |
| 2-1 | OC-11 | comparative | 100 | 100 | 55 | comparative |
| Connection A | Example | |||||
| 2-2 | OC-11 | comparative | 102 | 79 | 62 | comparative |
| Connection B | Example | |||||
| 2-3 | OC-11 | DP-1 | 121 | 316 | 97 | Gift |
| invention | ||||||
| 2-4 | OC-30 | DP-2 | 123 | 281 | 94 | Gift |
| invention | ||||||
| 2-5 | OC-4 | DP-3 | 111 | 240 | 80 | Gift |
| invention | ||||||
| 2-6 | OC-12 | DP-32 | 113 | 132 | 81 | Gift |
| invention | ||||||
| 2-7 | OC-29 | DP-6 | 109 | 103 | 72 | Gift |
| invention | ||||||
| 2-8 | OC-30 | DP-8 | 106 | 109 | 79 | Gift |
| invention | ||||||
| 2-9 | 26 | DP-49 | 105 | 106 | 84 | Gift |
| invention | ||||||
| 2-10 | 1 | DP-77 | 104 | 110 | 71 | Gift |
| invention | ||||||
| 2-11 | 42 | DP-85 | 107 | 204 | 79 | Gift |
| invention | ||||||
| 2-12 | OC-30 | DP-57 | 117 | 293 | 93 | Gift |
| invention | ||||||
As clearly shown in Table 2, the organic EL elements 2-3 to 2-12 of the present invention exhibit higher luminance efficiency and longer lifetime compared to the organic EL elements 2-1 and 2-2 of the comparative examples. It has also been found to improve properties of an element such as B. excellent long-term stability.
«Production of the organic element 3-1»
A substrate (NA45, manufactured by NH Techno Glass Corp.) made by forming an ITO (Indium Tin Oxide) film with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm was used shaped to form a positive electrode. A transparent base substrate provided with the ITO transparent electrode was cleaned with ultrasonic waves using isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone washing for 5 minutes.
The transparent support substrate was attached to the substrate support of a commercially available vacuum deposition apparatus. A molybdenum resistance heating vessel was filled with 200 mg of α-NPD as an orifice transport material, another molybdenum resistance heating vessel was filled with 200 mg of OC-11 as a host compound, another molybdenum resistance heating vessel was filled with molybdenum filled with 200 mg of ET-11 as an electron transport material, and another molybdenum resistance heating vessel was filled with 100 mg of comparative compound A as a doping compound, and another molybdenum resistance heating vessel was filled with 100 mg of comparative compound A as a doping compound, and another molybdenum resist was filled with 100 mg of D- 10 filled as a doping compound. Then they were put into the vacuum deposition apparatus.
Then, a vacuum vessel was depressurized to 4×10−4Pa and then the heating container containing α-NPD was heated by vapor deposition electrification at a deposition rate of 0.1 nm/s to form an orifice transport layer with a film thickness of 20 nm on the transparent supporting substrate.
In addition, the heating canisters containing OC-11 as the host compound and Comparative Compounds A and D-1 as the dopant compound were heated by electrification so that the vapor deposition ratio was 100:5:0.6 for OC-11, respectively. Comparative Compounds A and D-1 for deposition on the wellbore transport layer. As a result, a light-emitting layer having a film thickness of 30 nm was formed.
In addition, the heating vessel containing ET-11 was heated by electrification to evaporate it on a light-emitting layer at a deposition rate of 0.1 nm/s to form an electron transport layer with a film thickness of 30 nm.
At this time, the temperature of the substrate at the time of vapor deposition was room temperature.
Subsequently, lithium fluoride was deposited to form a 0.5 nm thick negative electrode buffer layer, and aluminum was further deposited to form a 110 nm thick negative electrode. Consequently, the organic EL element 3-1 was thus manufactured. As a result of electrification of the produced 3-1 organic EL element, almost white light was obtained. Therefore, it was found that it can be used as a lighting device. However, it was also verified that the white light emission is obtained in a similar manner even when the substitution is made with other exemplary compounds.
«Production of the organic element 3-2 to 3-7»
The organic EL elements 3-2 to 3-7 were manufactured in the same manner as the organic EL element 3-1 except that the doping compounds in the light-emitting layer were changed to the compounds described in Table 3.
"Classification of Organic Elements EL 3-1 to 3-7"
For the evaluation of the obtained Organic EL Elements 3-1 to 3-7, the Organic EL Elements were sealed in the same manner as the Organic EL Elements 1-1 to 1-10 of Example 1 and after illumination was generated as illustrated in Fig. 5 and Fig. 6 the evaluation was carried out.
External quantum extraction efficiency, half-life, long-term stability and thermal stability were evaluated in the same manner as in Example 1 for each sample prepared as described above. The evaluation results are described in Table 3. Meanwhile, the results of measurement of the quantum efficiency and half-life are described in Table 3 as a relative value compared to the value set at 100 of the organic EL element 3-1.
| Tabla 3 | |||||||
| Extern | |||||||
| extraction | |||||||
| Organic | Quantum | Bad | long term | Thermal | |||
| the element | host | Dopant | efficiency | Life | stability | stability | Comments |
| 3-1 | OC-11 | comparative | 100 | 100 | 54 | 59 | comparative |
| Connection A | Example | ||||||
| 3-2 | OC-11 | comparative | 109 | 80 | 73 | 93 | comparative |
| Connection B | Example | ||||||
| 3-3 | OC-11 | DP-1 | 118 | 261 | 96 | 100 | Gift |
| invention | |||||||
| 3-4 | OC-11 | DP-2 | 120 | 237 | 94 | 102 | Gift |
| invention | |||||||
| 3-5 | OC-30 | DP-13 | 121 | 203 | 97 | 99 | Gift |
| invention | |||||||
| 3-6 | OC-15 | DP-21 | 122 | 199 | 83 | 87 | Gift |
| invention | |||||||
| 3-7 | 1 | DP-40 | 111 | 158 | 90 | 92 | Gift |
| invention | |||||||
As clearly shown in Table 3, each of the organic EL elements 3-3 to 3-7 of the present invention exhibits higher luminance efficiency and longer lifetime compared to the organic EL elements 3-1 and 3-2 of the comparative examples. It has also been found to improve properties of an element such as B. excellent long-term stability. In addition, with respect to the organic EL elements 3-1 and 3-2 of the comparative examples, the first-prepared element, the third-prepared element, and the fifth-prepared element showed a gradually decreasing half-life. However, with respect to the organic EL elements 3-3 to 3-7 of the present invention, the first-produced element, the third-produced element and the fifth-produced element showed almost no reduction in half-life. Therefore, it was found that the dopant compound used in the organic EL element of the present invention has excellent thermal stability.
PAY. 7A to 7E are schematic diagrams showing the construction of a full-color organic EL display device.
A substrate (NA45, manufactured by NH Techno Glass Corp.) made by forming an ITO transparent electrode film202with a thickness of 100 nm on a glass substrate201, was patterned at a pitch of 100 µm to form a positive electrode (see Fig. 7A). Then on glass substrate201and between transparent ITO electrodes202, non-photosensitive polyimide partition203(20 µm wide and 2.0 µm thick) was formed by photolithography (see Fig. 7B).
ON THIS electrode202and between the medians203the composition for the hole ejecting layer having the following composition was ejected and ejected using an ink jet head (manufactured by Seiko Epson Corp.: MJ800C). It was then irradiated with ultraviolet light for 200 seconds and subjected to a drying treatment at 60°C for 10 minutes to form the hole injection layer.204with a film thickness of 40 nm (see Fig. 7C).
In the hole injection layer204For example, a blue light-emitting layer composition, a green light-emitting layer composition, and a red light-emitting layer composition each having the following composition were ejected and injected with ink using an injection head. Next, it was subjected to a drying treatment at 60°C for 10 minutes to form the light-emitting layer.205B,205GRAMM,205R, which has any color (see Fig. 7D).
Then to cover each layer of color development205B,205GRAMM,205R, an electron transport layer was deposited to form a 20 nm film thickness electron transport layer (not shown). With further deposition of lithium fluoride, a negative electrode buffer layer having a film thickness of 0.6 nm (not shown) was formed, and Al was deposited to form the negative electrode.206with a layer thickness of 130 nm. As a result, an organic EL element was manufactured (see Fig. 7E).
When voltage was applied to each electrode of the produced organic EL elements, blue color, green color and red color were displayed, and therefore it was found that they can be used as a color display device.
(Composition for hole injection layer)
| Panel carrier material 7 (Compound 7) | 20 pieces in bulk | |
| Cyclohexylbenzeno | 50 pieces in bulk | |
| Isopropylbiphenyl | 50 pieces in bulk | |
(Composition for Blue Light Emitting Layer)
| Host Material 2 (Compound 2) | 0.7 parts by mass | |
| DP-1 | 0.04 parts by mass | |
| Cyclohexylbenzeno | 50 pieces in bulk | |
| Isopropylbiphenyl | 50 pieces in bulk | |
(Composition for Green Light Emitting Layer)
| Host Material 2 (Compound 2) | 0.7 parts by mass | |
| D-1 | 0.04 parts by mass | |
| Cyclohexylbenzeno | 50 pieces in bulk | |
| Isopropylbiphenyl | 50 pieces in bulk | |
(Composition for the red light-emitting layer)
| Host Material 2 (Compound 2) | 0.7 parts by mass | |
| D-10 | 0.04 parts by mass | |
| Cyclohexylbenzeno | 50 pieces in bulk | |
| Isopropylbiphenyl | 50 pieces in bulk | |