JP2011213643A - Copper complex compound and organic luminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic luminescent element generating high luminescence light in extremely high efficiency.SOLUTION: The organic luminescent element includes at least one kind of copper complex compounds expressed e.g. by formula (2). In the formula, R is a hydrogen atom, alkyl, aryl, heterocyclic group or the like.

Description

  The present invention relates to a copper complex compound and an organic light emitting device using the same.

  An organic light emitting device is an electronic device in which a thin film containing a fluorescent organic compound or a phosphorescent organic compound is sandwiched between an anode and a cathode. Further, by injecting electrons and holes (holes) from each electrode to generate excitons of a fluorescent compound or a phosphorescent compound, the organic light emitting device emits light when the excitons return to the ground state. .

  Recent advances in organic light-emitting devices are remarkable, and their features include high brightness, a wide variety of emission wavelengths, high-speed response, and reduction in thickness and weight of light-emitting devices with a low applied voltage. This suggests that the organic light emitting device has a wide range of uses.

  However, under the present circumstances, light output with higher brightness or higher conversion efficiency is required. In addition, there are still many problems in terms of durability, such as changes over time due to long-term use and deterioration due to atmospheric gas containing oxygen or moisture. Furthermore, when considering application to a full-color display or the like, light emission of blue, green, and red with high color purity is required, but it cannot be said that these problems have been sufficiently solved.

  In recent years, many studies have been made on using phosphorescent compounds as light emitting materials and using triplet state energy for EL light emission. A group of Princeton University reports that an organic light emitting device using an iridium complex as a light emitting material exhibits high luminous efficiency (Non-patent Document 1). Further, studies have been made on converting triplet state energy into singlet and using it for EL emission (Patent Document 1 and Patent Document 2).

JP 2004-241374 A Japanese Patent Laid-Open No. 2006-024830

Nature, 395, 151 (1998)

  An object of the present invention is to provide an organic light emitting device having extremely high efficiency and high luminance light output.

  The copper complex compound of the present invention is represented by the following general formula (1).

（式（１）において、Ｒ₁は、アルキル基、アリール基又は複素環基を表す。各Ｒ₁は、それぞれ同じであってもよいし異なっていてもよい。Ｒ₂は、水素原子、アルキル基、アリール基又は複素環基を表す。各Ｒ₂は、それぞれ同じであってもよいし異なっていてもよい。Ｒ₃は、水素原子、フッ素原子、アルキル基、アリール基又は複素環基を表す。各Ｒ₃は、それぞれ同じであってもよいし異なっていてもよい。またＲ₁乃至Ｒ₃は、それぞれ同じであっても異なっていてもよい。Ａは、アリーレン基又はヘテロアリーレン基を表す。Ｃｕは、１価の銅イオンを表す。）

(In Formula (1), R ₁ represents an alkyl group, an aryl group, or a heterocyclic group. Each R ₁ may be the same or different. R ₂ is a hydrogen atom or an alkyl group. Each R ₂ may be the same or different, and R ₃ represents a hydrogen atom, a fluorine atom, an alkyl group, an aryl group or a heterocyclic group. Each R ₃ may be the same or different, and R _{1 to} R ₃ may be the same or different, and A is an arylene group or a heteroarylene group. Cu represents a monovalent copper ion.)

  According to the present invention, it is possible to provide an organic light-emitting element capable of outputting light with extremely high efficiency and high luminance. In addition, the organic light emitting device of the present invention can be manufactured using vacuum deposition, casting method, or the like, and can be easily manufactured at a relatively low cost and in a large area.

It is a cross-sectional schematic diagram which shows the example of embodiment in the organic light emitting element of this invention. 4 is a diagram showing an emission spectrum (PL spectrum) in a crystalline state of exemplary compound Cu-42 synthesized in Example 1. FIG. 6 is a graph showing an emission spectrum (EL spectrum) of an organic light emitting device produced in Example 4. FIG. 6 is a diagram showing an emission spectrum (EL spectrum) of an organic light emitting device produced in Example 5. FIG.

  Hereinafter, the present invention will be described in detail. The copper complex compound of the present invention is represented by the following general formula (1).

（式（１）において、Ｒ₁は、アルキル基、アリール基又は複素環基を表す。各Ｒ₁は、それぞれ同じであってもよいし異なっていてもよい。Ｒ₂は、水素原子、アルキル基、アリール基又は複素環基を表す。各Ｒ₂は、それぞれ同じであってもよいし異なっていてもよい。Ｒ₃は、水素原子、フッ素原子、アルキル基、アリール基又は複素環基を表す。各Ｒ₃は、それぞれ同じであってもよいし異なっていてもよい。またＲ₁乃至Ｒ₃は、それぞれ同じであっても異なっていてもよい。Ａは、アリーレン基又はヘテロアリーレン基を表す。Ｃｕは、１価の銅イオンを表す。）

(In Formula (1), R ₁ represents an alkyl group, an aryl group, or a heterocyclic group. Each R ₁ may be the same or different. R ₂ is a hydrogen atom or an alkyl group. Each R ₂ may be the same or different, and R ₃ represents a hydrogen atom, a fluorine atom, an alkyl group, an aryl group or a heterocyclic group. Each R ₃ may be the same or different, and R _{1 to} R ₃ may be the same or different, and A is an arylene group or a heteroarylene group. Cu represents a monovalent copper ion.)

  Next, the substituent shown by the copper complex compound of Formula (1) is demonstrated in detail.

Examples of the alkyl group represented by R ₁ include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, a tertiary butyl group, an octyl group, a cyclohexyl group, and a trifluoromethyl group.

As the aryl group represented by R ₁ , phenyl group, biphenyl group, terphenyl group, fluorenyl group, naphthyl group, fluoranthenyl group, anthryl group, phenanthryl group, pyrenyl group, tetracenyl group, pentacenyl group, triphenylenyl group, perylenyl Groups and the like.

Examples of the heterocyclic group represented by R ₁ include a pyrazolyl group, a thienyl group, a pyrrolyl group, a pyridyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, a quinolyl group, and an isoquinolyl group.

  The alkyl group, aryl group and heterocyclic group may further have a substituent. Specifically, an alkyl group such as a methyl group, an ethyl group, and a propyl group, an aryl group such as a phenyl group and a biphenyl group, a thienyl group, a pyrrolyl group, and a pyridyl group Heterocyclic groups, amino groups such as dimethylamino groups, diethylamino groups, dibenzylamino groups, diphenylamino groups, ditolylamino groups, dianisolylamino groups, halogen atoms such as fluorine, chlorine, bromine, iodine, etc. are further substituted. Also good.

Specific examples of the alkyl group, aryl group and heterocyclic group represented by R ₂ are the same as the specific examples of the alkyl group, aryl group and heterocyclic group represented by R ₁ . Further, the alkyl group, aryl group and heterocyclic group represented by R ₂ may further have a substituent, and specific examples of the substituent are the same as those for R ₁ .

Specific examples of the alkyl group, aryl group and heterocyclic group represented by R ₃ are the same as the specific examples of the alkyl group, aryl group and heterocyclic group represented by R ₁ . Further, the alkyl group, aryl group and heterocyclic group represented by R ₃ may further have a substituent, and specific examples of the substituent are the same as those for R ₁ .

  Examples of the arylene group represented by A include a phenylene group, a naphthylene group, and a biphenylene group.

  Examples of the heteroarylene group represented by A include a pyridylene group, a quinolylene group, an isoquinolylene group, and a quinoxarylene group.

  The arylene group and heteroarylene group may further have a substituent. Specifically, an alkyl group such as a methyl group, an ethyl group, or a propyl group, an aryl group such as a phenyl group or a biphenyl group, a heterocyclic group such as a thienyl group, a pyrrolyl group, or a pyridyl group, An amino group such as a dimethylamino group, a diethylamino group, a dibenzylamino group, a diphenylamino group, a ditolylamino group, a dianisolylamino group, or a halogen atom such as fluorine, chlorine, bromine, or iodine may be further substituted.

  The copper complex compound of the present invention is preferably a compound represented by the following general formula (2).

（式（２）において、Ｒは、水素原子、アルキル基、アリール基又は複素環基を表す。各Ｒは、それぞれ同じであってもよいし異なっていてもよい。Ｃｕは１価の銅イオンを表す。）

(In Formula (2), R represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. Each R may be the same or different. Cu is a monovalent copper ion. Represents.)

  Next, the substituent shown by the copper complex compound of Formula (2) is demonstrated in detail.

  Examples of the alkyl group represented by R include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal propyl group, a tertiary butyl group, and a cyclohexyl group.

  As the aryl group represented by R, phenyl group, biphenyl group, terphenyl group, fluorenyl group, naphthyl group, fluoranthenyl group, anthryl group, phenanthryl group, pyrenyl group, tetracenyl group, pentacenyl group, triphenylenyl group, perylenyl group, etc. Is mentioned.

  Examples of the heterocyclic group represented by R include a pyrazolyl group, a thienyl group, a pyrrolyl group, a pyridyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, a quinolyl group, and an isoquinolyl group.

  The alkyl group, aryl group and heterocyclic group may further have a substituent. Specifically, an alkyl group such as a methyl group, an ethyl group, and a propyl group, an aryl group such as a phenyl group and a biphenyl group, a thienyl group, a pyrrolyl group, and a pyridyl group Heterocyclic groups, amino groups such as dimethylamino groups, diethylamino groups, dibenzylamino groups, diphenylamino groups, ditolylamino groups, dianisolylamino groups, halogen atoms such as fluorine, chlorine, bromine, iodine, etc. are further substituted. Also good.

  The copper complex compound of the present invention preferably emits delayed fluorescence.

  In organic light emitting devices, the generation ratio of excitons (singlet excitons and triplet excitons) generated by recombination of electrons and holes is determined by the singlet excitons: triplet excitons based on the multiplicity of spins. = 25%: 75%. Here, when a fluorescent compound that uses only singlet energy for EL emission is used as the light emitting material, the theoretical limit value of the external quantum efficiency is about 5% at most.

  Therefore, when the copper complex compound of the present invention that emits delayed fluorescence is used as a constituent material of an organic light emitting device, when triplet excitons are generated, the triplet excitons absorb thermal energy at room temperature, Occurs to generate singlet excitons. And fluorescence can be emitted from this singlet exciton. Therefore, the triplet exciton generated theoretically 75% can be used for fluorescence emission. That is, triplet excitons can be converted into singlet excitons by room temperature energy, and fluorescence can be emitted from all excitons. In addition, it is thought that the theoretical limit value of external quantum efficiency at this time reaches 20%. In addition, since the light emitting element using the delayed fluorescent compound emits light from a singlet, the driving voltage can be expected to be the same as the light emitting element using a normal fluorescent compound.

The delayed fluorescence emission, which is a characteristic of the copper complex compound of the present invention, has the following characteristics.
(1) The emission lifetime at room temperature (298K) is on the microsecond level (2) The emission wavelength at room temperature (298K) is shorter than the emission wavelength at low temperature (77K) (3) The emission lifetime at room temperature (298K) , Significantly shorter than the light emission lifetime at low temperature (77K) (4) The emission intensity is improved by the increase in temperature

  Comparing the emission wavelength of fluorescent emission and phosphorescence emission at room temperature with the emission wavelength of fluorescence emission and phosphorescence emission at low temperature, the same wavelength or the lower temperature is usually shorter. On the other hand, in the copper complex compound of the present invention that emits delayed fluorescence, the lower temperature has a longer wavelength. This is because light emission from a singlet is observed at room temperature, but light is emitted from a triplet energy level lower than the singlet at a low temperature. The light emission wavelength here means the maximum light emission wavelength or the light emission start wavelength.

  Further, since the fluorescence emission is emission from a singlet, the emission lifetime is usually on the nanosecond level. On the other hand, the phosphorescence emission in which the triplet is involved in the emission has an emission lifetime of the microsecond level or more. Similarly, in the delayed fluorescence emission, since the triplet is involved in the emission, the emission lifetime becomes the microsecond level or more. However, if the emission lifetime is too long, the emission efficiency may be lowered due to exciton saturation in the light-emitting element. Therefore, the emission lifetime of the copper complex compound of the present invention is 0 in a solid state or a dilute solution state. .1 microsecond or more and less than 1 millisecond is preferable.

  As described above, the emission lifetimes of delayed fluorescence and phosphorescence are on the order of microseconds or more, but the characteristic of delayed fluorescence is that the emission lifetime at room temperature is significantly shorter than the emission lifetime at low temperatures. . For example, when it is assumed that a phosphorescent compound having a quantum yield of 0.1 at room temperature and non-radiation deactivation at a low temperature is completely suppressed, the emission lifetime at low temperature is 10 times the emission lifetime at room temperature. It is. On the other hand, in the case of delayed fluorescence emission, light is emitted from a singlet at room temperature, but light is emitted from a triplet at low temperature, so the emission lifetime at low temperature is more than 10 times the emission lifetime at room temperature. Sometimes it grows. In the copper complex compound of the present invention, the emission lifetime is preferably 10 times or more the emission lifetime at room temperature in the solid state or dilute solution state, more preferably 50 times or more, A ratio of 100 times or more is particularly preferable.

  Furthermore, in phosphorescence emission, the non-radiation deactivation rate usually increases with increasing temperature, so the emission intensity decreases with increasing temperature. On the other hand, in the case of delayed fluorescence, the emission intensity increases with increasing temperature. This is because triplet and singlet crossing probabilities due to the Boltzmann distribution increase due to an increase in external temperature energy, and triplet excitons easily cross between singlets to singlet excitons. .

  On the other hand, in order to obtain delayed fluorescence, it is necessary to reduce the energy difference between the lowest triplet excitation energy and the lowest singlet excitation energy to facilitate the intersystem crossing of triplet excitons to singlet excitons. There is. This intersystem crossing is essentially a spin forbidden transition. Here, a method using the heavy atom effect is known as a method of weakening spin forbiddenness. Here, when a molecule having a large atomic number is used, phosphorescence is generated by releasing the spin forbidden state from the lowest triplet excited state to the ground state due to the heavy atom effect, but it is considered that delayed fluorescence is difficult to obtain. If a molecule having a small atomic number is used, the spin-forbidden state is not solved because the heavy atom effect is weak, and it is considered that delayed fluorescence is difficult to obtain because triplet energy is non-radiatively deactivated as thermal energy. Therefore, in the present invention, a copper atom having a suitable atomic weight is employed as the central metal of the compound in order to utilize the heavy electron effect. This solves the spin forbidden that inhibits intersystem crossing from triplet excitons to singlet excitons, suppresses non-radiative deactivation from the triplet excited state to the ground state, and provides strong delayed fluorescence at room temperature. Can be obtained.

Here, several possibilities can be considered about the light emission mechanism of the copper complex compound of this invention.
(1) LMCT (ligand-to-metal-charge-transfer) excited state (2) MLCT (metal-to-ligand-charge-transfer) excited state (3) LLCT (ligand-to-ligand-charge-transfer) excited state State (4) Metal center excited state (5) Ligand center (π-π ^* ) excited state (6) Ligand center (n-π ^* ) excited state

  As described above, in order to achieve delayed fluorescence, it is necessary to bring the lowest triplet excitation energy and the lowest singlet excitation energy close to each other. By the way, it is known that the lowest triplet excitation energy and the lowest singlet excitation energy are closer in the CT excited state such as the LMCT excited state, MLCT excited state, and LLCT excited state than the ligand center excited state. ing. Therefore, the copper complex compound of the present invention is preferably a compound that can take a CT-excited state. Furthermore, it is more preferable that the copper complex compound of the present invention emits light from an MLCT excited state where stronger light emission can be expected.

  In addition, the fact that the lowest triplet excitation energy and the lowest singlet excitation energy of the ligand involved in light emission are close to each other is one of the important factors for achieving delayed fluorescence emission. Here, the copper complex compound of the present invention has a diphosphine moiety which is an important ligand for obtaining a complex having delayed fluorescence emission because the lowest triplet excitation energy and the lowest singlet excitation energy are close to each other.

Furthermore, the copper complex compound of the present invention can be expected to emit light from an MLCT excited state from a monovalent copper ion (Cu ⁺ ) as a central metal to a diphosphine site of a ligand. Here, in order to promote the MLCT excited state from the monovalent copper ion (Cu ⁺ ) as the central metal to the diphosphine site of the ligand, the diphosphine site preferably has π electrons. Therefore, it is preferable that A or R ₁ in the general formula (1) includes a substituent having π electrons. Specifically, it is preferable that A is an arylene group or a heteroarylene group. Similarly, R ₁ is preferably an aryl group or a heterocyclic group. However, if the π electron is too large, light emission from the ligand center (π-π ^* ) excited state is also promoted. Therefore, A and R1 in the general formula (1) are single groups represented by a benzene ring and a pyridine ring. A ring aromatic group or a heterocyclic group is preferred. On the other hand, since a heterocyclic ring may promote a ligand center (n-π ^* ) excited state, it is particularly preferable that A is a phenylene group. Similarly, it is particularly preferred that R ₁ is a phenyl group.

In addition, the copper complex compound of the present invention is preferably a neutral copper complex from the viewpoints of vapor deposition properties and molecular stability when producing a light emitting device. Therefore, the copper complex compound of the present invention desirably uses pyrazolyl borate as a ligand for neutralization of the compound. The copper complex compound obtained in this way can be deposited and becomes a chemically stable compound. Further, from the viewpoint of ease of synthesis and molecular stability, in general formula (1), R ₃ is particularly preferably a hydrogen atom. Furthermore, from the viewpoint of improving the symmetry of the molecule and improving the stability, in the general formula (1), R ₂ is particularly preferably the same substituent.

  Hereinafter, specific structural formulas of the copper complex represented by the general formula (1) used in the present invention are shown below. However, these are merely representative examples, and the present invention is not limited thereto. In the table, Me represents a methyl group, Et represents an ethyl group, iPr represents an isopropyl group, nPr represents a normal propyl group, tBu represents a tertiary butyl group, Cy represents a cyclohexyl group, and Ph represents a phenyl group.

  Next, the organic light emitting device of the present invention will be described in detail.

  The organic light emitting device of the present invention comprises an anode, a cathode, and an organic compound layer sandwiched between the anode and the cathode. In the organic light emitting device of the present invention, the organic compound layer contains at least one kind of the copper complex compound of the present invention. The organic light-emitting device of the present invention preferably emits light by applying a voltage between the anode and the cathode.

  Hereinafter, the organic light-emitting device of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of the organic light-emitting device of the present invention. 1A to 1F show first to sixth embodiments of the organic light-emitting device of the present invention, respectively. Each embodiment will be described below.

  In the organic light emitting device 10 of FIG. 1A, an anode 2, a light emitting layer 3, and a cathode 4 are sequentially provided on a substrate 1. This organic light emitting device 10 is useful when the light emitting layer 3 is composed of an organic compound having all of hole transport ability, electron transport ability, and light emitting performance. Moreover, it is useful also when the light emitting layer 3 is comprised by mixing the organic compound which has the characteristics in any one of hole transport ability, electron transport ability, and luminescent performance.

  In the organic light emitting device 20 of FIG. 1B, an anode 2, a hole transport layer 5, an electron transport layer 6, and a cathode 4 are sequentially provided on a substrate 1. This organic light emitting device 20 is useful when a light emitting organic compound having either a hole transporting property or an electron transporting property and an organic compound having only an electron transporting property or only a hole transporting property are used in combination. . In the organic light emitting device 20, the hole transport layer 5 or the electron transport layer 6 also serves as a light emitting layer.

  The organic light emitting device 30 in FIG. 1C is obtained by inserting the light emitting layer 3 between the hole transport layer 5 and the electron transport layer 6 in the organic light emitting device 20 in FIG. The organic light emitting device 30 has functions of separating carrier transport and light emission, and organic compounds having hole transport property, electron transport property, and light emission property can be used in appropriate combination. For this reason, the degree of freedom of material selection is greatly increased, and various compounds having different emission wavelengths can be used, so that the emission hue can be diversified. Furthermore, it is possible to effectively confine each carrier or exciton in the central light emitting layer 3 to improve the light emission efficiency of the organic light emitting device 30.

  An organic light emitting device 40 in FIG. 1D is obtained by providing a hole injection layer 7 between the anode 2 and the hole transport layer 5 in the organic light emitting device 30 in FIG. Since the organic light emitting element 40 is provided with the hole injection layer 7, the adhesion between the anode 2 and the hole transport layer 5 or the hole injection property is improved. It is.

  The organic light emitting device 50 of FIG. 1 (e) is a layer (hole / exciton blocking layer) that prevents holes or excitons (excitons) from passing to the cathode 4 side in the organic light emitting device 30 of FIG. 1 (c). 8) is inserted between the light emitting layer 3 and the electron transport layer 6. By using an organic compound having a very high ionization potential as the hole / exciton blocking layer 8, the light emission efficiency of the organic light emitting device 50 is improved.

  An organic light emitting device 60 in FIG. 1 (f) is obtained by inserting a hole / exciton blocking layer 8 between the light emitting layer 3 and the electron transport layer 6 in the organic light emitting device 40 in FIG. 1 (d). . By using a compound having a very high ionization potential as the hole blocking layer 8, the light emission efficiency of the organic light emitting device 60 is improved.

  However, FIGS. 1A to 1F are very basic device configurations, and the configuration of the organic light emitting device using the copper complex compound of the present invention is not limited to these. For example, various layer configurations such as providing an insulating layer, an adhesive layer, or an interference layer at the interface between the electrode and the organic layer, and the hole transport layer including two layers having different ionization potentials can be employed.

  The copper complex compound of the present invention exhibits high luminous efficiency and is suitable for a light emitting material. In addition, it is characterized in that it emits stronger light than other compounds, particularly in a solid powder state.

  In general, even in the case of a compound that emits light strongly in a dilute solution state, light emission is often extremely weak in a solid powder state. This is because, in the ground state or the excited state, a phenomenon (concentration quenching phenomenon) in which the original light emission characteristics cannot be obtained is generated by forming an aggregate by the interaction between the light emitting material molecules. On the other hand, the copper complex compound of the present invention is a light-emitting material that is strong against concentration quenching. As described above, since the material used for the organic light emitting device of the present invention has few restrictions on concentration quenching, the concentration in the light emitting layer can be increased or a light emitting layer of 100% of the material can be formed. Therefore, a light-emitting element having high luminous efficiency and high productivity can be manufactured. When using the copper complex compound of this invention as a light emitting material of the light emitting layer 3, Preferably the content is 0.1 to 100 weight% with respect to the weight of the whole material which comprises a light emitting layer.

  The copper complex compound of the present invention may be included as a constituent material of the light emitting layer (light emitting material) constituting the organic compound layer, but a layer other than the light emitting layer constituting the organic compound layer, for example, a hole injection layer, It may also be contained in a hole transport layer, an electron injection layer, an electron transport layer, an electron barrier layer, and the like.

  On the other hand, although the light emitting layer 3 may be comprised only with the copper complex compound of this invention, it may be comprised from the host and the guest. When the light emitting layer 3 is comprised from a host and a guest, the copper complex compound of this invention may be used as a host and may be used as a guest.

  The organic light-emitting device of the present invention preferably uses a copper complex compound that emits delayed fluorescence as the light-emitting material of the light-emitting layer, and has heretofore been known hole-transporting compounds, light-emitting compounds, or electron-transporting compounds. Etc. can be used together as necessary. Examples of these compounds are given below.

  The constituent material of the anode 2 should have a work function as large as possible. For example, a simple metal such as gold, platinum, nickel, palladium, cobalt, selenium, vanadium, or an alloy thereof, or a metal oxide such as tin oxide, zinc oxide, indium tin oxide (ITO), or indium zinc oxide can be used. In addition, conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyphenylene sulfide can also be used. One of these electrode materials may be used alone, or a plurality of these electrode materials may be used in combination.

  On the other hand, the constituent material of the cathode 4 should have a small work function. For example, simple metals such as lithium, sodium, potassium, cesium, calcium, magnesium, aluminum, indium, silver, lead, tin, chromium, or alloys thereof can be used. A metal oxide such as indium tin oxide (ITO) can also be used. Moreover, the cathode may be composed of a single layer or a plurality of layers.

  The substrate 1 used in the present invention is not particularly limited, and an opaque substrate such as a metal substrate or a ceramic substrate, or a transparent substrate such as glass, quartz, or a plastic sheet is used. It is also possible to control the color light by using a color filter film, a fluorescent color conversion filter film, a dielectric reflection film or the like on the substrate.

  Note that a protective layer or a sealing layer can be provided for the manufactured element in order to prevent contact with oxygen, moisture, or the like. Examples of the protective layer include diamond thin films, inorganic material films such as metal oxides and metal nitrides, polymer films such as fluorine resin, polyparaxylene, polyethylene, silicone resin, polystyrene resin, and photo-curing resins. It is done. Further, it is possible to cover glass, a gas-impermeable film, a metal, etc., and to package the element itself with an appropriate sealing resin.

  In the organic light-emitting device of the present invention, the organic compound layer such as the light-emitting layer 3 is generally formed by forming a thin film by a vacuum evaporation method or a coating method after dissolving in an appropriate solvent. In view of the possibility of reduction in the light emission efficiency and lifetime of the light emitting element due to the possibility of impurity contamination, it is particularly preferable to fabricate the organic light emitting element by a vacuum deposition method. Moreover, when forming into a film by the apply | coating method, a film | membrane can also be formed combining with a suitable binder resin.

  The binder resin can be selected from a wide range of binder resins such as polyvinyl carbazole resin, polycarbonate resin, polyester resin, polyarylate resin, polystyrene resin, acrylic resin, methacrylic resin, butyral resin, polyvinyl acetal resin, diallyl phthalate resin. , Phenol resin, epoxy resin, silicone resin, polysulfone resin, urea resin and the like, but are not limited thereto. Moreover, you may mix these 1 type, or 2 or more types as a single or copolymer polymer.

  In the organic light emitting device of the present invention, the thickness of the layer containing the condensed ring aromatic compound of the present invention is less than 10 μm, preferably 0.5 μm or less, more preferably 0.01 μm or more and 0.5 μm or less.

  The organic light emitting device of the present invention is preferably used as a display device in combination with a switching device. Here, the organic light emitting device of the present invention can be applied to products that require energy saving and high luminance. As an application example, a light source of a display device / illumination device or printer provided with the organic light emitting element of the present invention and a switching element, a backlight of a liquid crystal display device, and the like can be considered. As a display device, energy saving, high visibility, and a lightweight flat panel display are possible. Further, as the light source of the printer, the laser light source part of the laser beam printer that is widely used at present can be replaced with the organic light emitting device of the present invention. Elements that can be independently addressed are arranged on the array, and an image is formed by performing desired exposure on the photosensitive drum. By using the organic light emitting device of the present invention, the device volume can be greatly reduced. With respect to the lighting device and the backlight, the energy saving effect brought about by the organic light emitting device of the present invention can be expected.

  In application to a display, a method of driving using a TFT (Thin Film Transistor) element or the like as a switching element can be considered.

  The switching element included in the display device of the present invention is not particularly limited, and a single crystal silicon substrate, an MIM element, an a-Si type, or the like can be easily used.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

  [Example 1] Synthesis of exemplified compound Cu-42

(1) Synthesis of Synthesis Intermediate 1 Reagents and solvents shown below were charged into a reaction vessel under an argon stream.
1,2-bisdiphenylphosphinobenzene: 2 g (4.48 mmol)
Methylene chloride: 210ml

  Next, 643 mg (4.48 mmol) of copper (I) bromide was added to the reaction solution. Next, the reaction solution was stirred at room temperature for 12 hours. Next, the filtrate obtained by filtering out the precipitated insoluble matter was concentrated under reduced pressure until the amount of the solvent became small. Then, yellow crystals were obtained by slowly adding diethyl ether to the concentrated filtrate. Next, the yellow crystals were collected by filtration and vacuum-dried to obtain 2.6 g of synthetic intermediate 1 (yield 99%).

(2) Synthesis of Exemplified Compound Cu-42 The following reagents and solvent were charged in a reaction vessel under an argon stream.
Synthesis intermediate 1: 590 mg (0.5 mmol)
Tetrahydrofuran: 50ml

  Next, 350 mg (1.1 mmol) of tetrakis (1-pyrazolyl) borate potassium was added to the reaction solution. Next, the reaction solution was stirred at room temperature for 12 hours. Next, the filtrate obtained by filtering out the precipitated insoluble matter was concentrated under reduced pressure until the amount of the solvent became small. Next, yellow crystals were obtained by slowly adding hexane to the concentrated filtrate. Next, the yellow crystals were collected by filtration and dried under vacuum to obtain 752 mg (yield 95%) of Exemplary Compound Cu-42.

  The structure of this compound was confirmed by NMR measurement.

¹ H-NMR (500 MHz, CDCl ₃ ): δ = 7.48 (m, 6H), 7.32 (m, 6H), 7.24 (m, 12H), 7.09 (m, 12H).
Next, the obtained crystal was recrystallized in methylene chloride / hexane to perform single crystal analysis, and the crystal structure of this compound was confirmed.

a single crystal X-ray diffraction study: a = 11.9426 (11) Å, b = 18.5901 (16) Å, c = 17.7346 (17) Å, β = 105.425 (2) deg, V ^{= 3795.5 (6) Å 3,} monoclinic P21 / c, Z = 4, θ min / max = 1.6 / 32.6deg, 11036 unique observed reflections were used to refine 524 atomic parameters and gave a final R factor of 0.0466.

  The obtained compound was measured for light emission characteristics in a crystalline state. Here, the delayed fluorescence emission was determined by measuring the quantum yield and the emission lifetime. Specifically, first, emission quantum yield and absolute PL quantum yield of a sample in a powder, solution, or dispersion film state were measured at room temperature (298K). Next, the light emission lifetime of the sample was performed at room temperature (298K) and low temperature (77K). Here, if the emission lifetime at room temperature is at the microsecond level, it is considered that a triplet is involved in the emission, and it is found that the obtained compound emits phosphorescence or delayed fluorescence. Next, the value obtained by dividing the emission lifetime at room temperature (298K) by the emission lifetime at low temperature (77K) is evaluated. Specifically, if this value is 1/10 or less of the absolute PL quantum yield at room temperature (298 K), it is found that the emission is delayed fluorescence emission.

  In the measurement and evaluation, an absolute PL quantum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics) was used for measurement of the absolute PL quantum yield. The light emission lifetime was measured using a streak camera C4334 (manufactured by Hamamatsu Photonics) while exciting the sample with laser light.

  On the other hand, the temperature characteristic of emission intensity is also a material for determining delayed fluorescence emission. In the case of a delayed fluorescence compound, the emission intensity increases with increasing temperature. Therefore, it can be comprehensively judged whether or not the obtained compound emits delayed fluorescence from the light emission lifetime, the relationship between the light emission lifetime and the quantum yield, and the temperature characteristic of the light emission intensity.

  As a result of various measurements, it was found that the maximum emission wavelength at room temperature was 545 nm, the maximum emission wavelength at 77 K was 569 nm, and the emission wavelength at room temperature was shorter. FIG. 2 is a diagram showing an emission spectrum (PL spectrum) in the crystalline state of the exemplary compound Cu-42 synthesized in this example. On the other hand, the quantum yield of the exemplary compound Cu-42 was 0.49 at room temperature, and the light emission lifetime was 4.9 microseconds at room temperature and 930 microseconds at 77K. For this reason, it was found that the emission lifetime at 77K was 190 times the emission lifetime at room temperature. Furthermore, when the emission intensity of the exemplary compound Cu-42 at 0 ° C. and room temperature was compared, an improvement in the emission intensity was observed when the room temperature was reached.

  From the above light emission characteristics, it was found that the exemplified compound Cu-42 is a delayed fluorescent material.

  On the other hand, the exemplary compound Cu-42 was examined for sublimation purification, and it was found that the exemplary compound Cu-42 was a sublimable compound.

  [Example 2] Synthesis of exemplified compound Cu-37

The following reagents and solvents were charged in a reaction vessel under an argon stream.
Synthesis intermediate 1: 236 mg (0.2 mmol)
Tetrahydrofuran: 15ml

  Next, 82 mg (0.44 mmol) of potassium dihydrobis (1-pyrazolyl) borate was added to the reaction solution. Next, the reaction solution was stirred at room temperature for 12 hours. Next, the filtrate obtained by filtering out the precipitated insoluble matter was concentrated under reduced pressure until the amount of the solvent became small. Next, yellow crystals were obtained by slowly adding hexane to the concentrated filtrate. Next, the yellow crystals were collected by filtration and vacuum-dried to obtain 200 mg (yield 75%) of Exemplary Compound Cu-37.

  The structure of this compound was confirmed by NMR measurement.

¹ H-NMR (500 MHz, CDCl ₃ ): δ = 7.57 (d, 2H), 7.54 (m, 2H), 7.46 (m, 2H), 7.29 (m, 12H), 7 .24 (m, 8H), 6.90 (d, 2H), 5.99 (t, 2H).

  Next, the obtained crystal was recrystallized in diethyl ether / hexane to perform single crystal analysis, and the crystal structure of this compound was confirmed.

a single crystal X-ray diffraction study: a = 18.5284 (11) Å, b = 14.004 (9) Å, c = 24.6771 (16) Å, V = 6401.4 (7) Å ³ , orthohombic P b ca, Z = 8, θ _{min / max} = 1.7 / 32.5 deg, 10191 unique observed reflections we used to refin 431 atomic parameters and gain 50

  The light emission characteristics in the crystalline state were measured by the same method as in Example 1. As a result, the maximum emission wavelength at room temperature was 565 nm, and the maximum emission wavelength at 77 K was 565 nm. Moreover, the quantum yield of the exemplary compound Cu-37 was 0.30 at room temperature. On the other hand, the emission lifetime of the exemplary compound Cu-37 was 2.2 μsec at room temperature and 350 μsec at 77K, and thus it was found that the emission lifetime at 77K was 159 times the emission lifetime at room temperature. Furthermore, when the emission intensity of the exemplified compound Cu-37 at 0 ° C. and room temperature was compared, an improvement in the emission intensity was observed when the room temperature was reached.

  From the above light emission characteristics, it was found that the exemplified compound Cu-37 is a delayed fluorescent material.

  On the other hand, when examination of sublimation purification was performed on the exemplified compound Cu-37, it was found that the exemplified compound Cu-37 was a sublimable compound.

  [Example 3] Synthesis of exemplified compound Cu-43

The following reagents and solvents were charged in a reaction vessel under an argon stream.
Synthesis intermediate 1: 236 mg (0.2 mmol)
Tetrahydrofuran: 15ml

  Next, 149 mg (0.44 mmol) of potassium diphenylbis (1-pyrazolyl) borate was added to the reaction solution. Next, the reaction solution was stirred at room temperature for 12 hours. Next, the filtrate obtained by filtering out the precipitated insoluble matter was concentrated under reduced pressure until the amount of the solvent became small. Next, yellow crystals were obtained by slowly adding hexane to the concentrated filtrate. Next, the yellow crystals were collected by filtration and vacuum-dried to obtain 268 mg (yield 83%) of the exemplified compound Cu-43.

  The structure of this compound was confirmed by NMR measurement.

¹ H-NMR (500 MHz, CDCl ₃ ): δ = 7.41 (m, 4H), 7.28 (m, 6H), 7.21 (m, 8H), 7.03 (m, 8H), 6 .82 (m, 8H), 6.76 (m, 4H), 6.00 (m, 2H).
Next, the obtained crystal was recrystallized in methylene chloride / hexane to perform single crystal analysis, and the crystal structure of this compound was confirmed.

a single crystal X-ray diffraction study: a = 9.6512 (8) Å, b = 22.813 (2) Å, c = 19.5335 (17) Å, β = 93.960 (2) deg, V ^{= 4290.4 (6) Å 3,} monoclinic P21 / c, Z = 4, θ min / max = 1.3 / 32.8deg, 13634 unique observed reflections were used to refine 574 atomic parameters and gave a final R factor of 0.0677.

  The light emission characteristics in the crystalline state were measured by the same method as in Example 1. As a result, the maximum emission wavelength at room temperature was 560 nm, and the maximum emission wavelength at 77 K was 560 nm. In addition, the quantum yield of the exemplary compound Cu-43 was 0.32 at room temperature. The emission lifetime was 2.3 μsec at room temperature and 272 μsec at 77K. It was found that the emission lifetime at 77K was 118 times the emission lifetime at room temperature. Furthermore, when the emission intensity at 0 ° C. and room temperature was compared, an improvement in emission intensity was observed when the room temperature was reached.

  From the above light emission characteristics, it was found that the exemplified compound Cu-43 is a delayed fluorescent material.

  On the other hand, the exemplary compound Cu-43 was examined for sublimation purification, and it was found that the exemplary compound Cu-43 was a sublimable compound.

Example 4 Production of Organic Light-Emitting Element The organic light-emitting element shown in FIG. 1 (c) was produced by the following method. First, an anode 2 was formed by depositing indium tin oxide (ITO) on a glass substrate (substrate 1) by sputtering. At this time, the film thickness of the anode 2 was 120 nm. Next, the substrate 1 on which the anode 2 was formed was ultrasonically cleaned successively with acetone and isopropyl alcohol (IPA), then boiled and cleaned with IPA, and then dried. Further, UV / ozone cleaning was performed. The glass substrate which performed the above process was used at the process mentioned later as a transparent conductive support substrate.

  Next, TCTA and chloroform shown below were mixed to prepare a chloroform solution.

  Next, the above chloroform solution was dropped on the anode 2 and a film was formed by spin coating to form a successful transport layer 5. At this time, the film thickness of the hole transport layer 5 was 30 nm.

Next, another organic compound layer and an electrode layer were continuously formed by performing vacuum deposition by resistance heating in a vacuum chamber of 10 ⁻⁵ Pa.

  Specifically, first, the compound H1 (host) and the exemplified compound Cu-42 (guest) shown below are formed on the hole transport layer 5 and the weight concentration ratio of the compound H1 and the exemplified compound Cu-42 is 90. : The light emitting layer 3 was formed by co-evaporation to be 10. At this time, the thickness of the light emitting layer 3 was set to 30 nm.

  Next, the compound E1 shown below was formed on the light emitting layer 3 to form the electron transport layer 6. At this time, the thickness of the electron transport layer 6 was set to 30 nm.

  Next, LiF was formed on the electron transport layer 6 to form a first metal electrode layer with a thickness of 0.5 nm. Finally, Al was deposited to a thickness of 70 nm as the second metal electrode layer. The first metal electrode layer (LiF film) and the second metal electrode layer (Al film) function as a cathode. As described above, an organic light emitting device was obtained.

  The characteristics of the produced organic light emitting device were examined. Here, the delayed fluorescence emission was determined by measuring the quantum yield and the emission lifetime. Specifically, first, a thin film (sample) to be a light emitting layer was prepared, and the light emission quantum yield and the absolute PL quantum yield of this sample were measured at room temperature (298K). Next, the light emission lifetime of the sample was performed at room temperature (298K) and low temperature (77K). Here, if the emission lifetime at room temperature is at the microsecond level, it is considered that a triplet is involved in the emission, and it is found that the obtained compound emits phosphorescence or delayed fluorescence. Next, the value obtained by dividing the emission lifetime at room temperature (298K) by the emission lifetime at low temperature (77K) is evaluated. Specifically, if this value is 1/10 or less of the absolute PL quantum yield at room temperature (298 K), it is found that the emission is delayed fluorescence emission.

  In the measurement and evaluation, an absolute PL quantum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics) was used for measurement of the absolute PL quantum yield. The light emission lifetime was measured using a streak camera C4334 (manufactured by Hamamatsu Photonics) while exciting the sample with laser light.

  On the other hand, the temperature characteristic of emission intensity is also a material for determining delayed fluorescence emission. In the case of a delayed fluorescence compound, the emission intensity increases with increasing temperature. Therefore, it can be comprehensively judged whether or not the obtained compound emits delayed fluorescence from the light emission lifetime, the relationship between the light emission lifetime and the quantum yield, and the temperature characteristic of the light emission intensity.

In addition, the current-voltage characteristics of the element were measured with a microammeter 4140B manufactured by Hured Packard, and the light emission luminance of the element was measured with BM7 manufactured by Topcon. In the organic light emitting device of this example, light emission with an emission luminance of 2250 cd / m ² was observed at an applied voltage of 6.0 V. FIG. 3 is a diagram showing an emission spectrum (EL spectrum) of the organic light emitting device manufactured in this example. The maximum current efficiency was as high as 25.5 cd / A. Furthermore, when this element was continuously energized in a nitrogen atmosphere, stable light emission was obtained even when energized continuously for 100 hours.

  On the other hand, when the light emission lifetime of the organic light emitting device of this example was measured by laser light excitation, a lifetime of 3.6 microseconds was observed. Further, when the emission intensity was measured with the current density kept constant, an increase in the emission intensity was observed with respect to the increase in temperature.

[Example 5] Preparation of organic light-emitting device In Example 4, the same method as in Example 4 except that the light-emitting layer 3 is formed by depositing the exemplified compound Cu-43 on the hole transport layer 5. Thus, an organic light emitting device was produced.

In the organic light emitting device of this example, light emission with an emission luminance of 410 cd / m ² was observed at an applied voltage of 6.0 V. FIG. 4 is a diagram showing an emission spectrum (EL spectrum) of the organic light emitting device produced in this example. The maximum current efficiency was as high as 4.5 cd / A. Furthermore, when this element was continuously energized in a nitrogen atmosphere, stable light emission was obtained even when energized continuously for 100 hours.

  On the other hand, when the emission lifetime of the organic light emitting device of this example was measured by laser light excitation, a lifetime of 1.3 microseconds was observed. Further, when the emission intensity was measured with the current density kept constant, an increase in the emission intensity was observed with respect to the increase in temperature.

  From the above results, it can be said that the organic light-emitting device of the present invention is a delayed fluorescence light-emitting device and can realize high efficiency.

  1: substrate, 2: anode, 3: light emitting layer, 4: cathode, 5: hole transport layer, 6: electron transport layer, 7: hole injection layer, 8: hole / exciton blocking layer, 10 (20, 30, 40, 50, 60): organic light emitting device

Claims (7)

A copper complex compound represented by the following general formula (1):

(In Formula (1), R ₁ represents an alkyl group, an aryl group, or a heterocyclic group. Each R ₁ may be the same or different. R ₂ is a hydrogen atom or an alkyl group. Each R ₂ may be the same or different, and R ₃ represents a hydrogen atom, a fluorine atom, an alkyl group, an aryl group or a heterocyclic group. Each R ₃ may be the same or different, and R _{1 to} R ₃ may be the same or different, and A is an arylene group or a heteroarylene group. Cu represents a monovalent copper ion.) It is shown by following General formula (2), The copper complex compound of Claim 1 characterized by the above-mentioned.

(In Formula (2), R represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. Each R may be the same or different. Cu is a monovalent copper ion. Represents.)   3. The copper complex compound according to claim 1, wherein the copper complex compound emits delayed fluorescence. An anode and a cathode;
An organic compound layer sandwiched between the anode and the cathode,
An organic light emitting device, wherein the organic compound layer contains at least one kind of the copper complex compound according to any one of claims 1 to 3.   The organic light emitting device according to claim 4, wherein the copper complex compound is contained in a light emitting layer.   6. The organic light-emitting device according to claim 4, wherein the copper complex compound emits delayed fluorescence.   A display device comprising: the light-emitting element according to claim 4; and a switching element.

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