WO2018186101A1 - Élément électroluminescent organique et procédé de fabrication d'élément électroluminescent organique - Google Patents

Élément électroluminescent organique et procédé de fabrication d'élément électroluminescent organique Download PDF

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WO2018186101A1
WO2018186101A1 PCT/JP2018/008977 JP2018008977W WO2018186101A1 WO 2018186101 A1 WO2018186101 A1 WO 2018186101A1 JP 2018008977 W JP2018008977 W JP 2018008977W WO 2018186101 A1 WO2018186101 A1 WO 2018186101A1
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light emitting
compound
layer
emitting layer
organic
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Japanese (ja)
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威人 並川
顕一 田畑
井上　暁
康生 宮田
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コニカミノルタ株式会社
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/12—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants
    • H10K50/121—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants for assisting energy transfer, e.g. sensitization
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/10—Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/10—Triplet emission
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers

Definitions

  • the present invention relates to an organic electroluminescence element and a method for manufacturing the organic electroluminescence element. More specifically, the present invention relates to an organic electroluminescent device having good luminous efficiency and luminance half life even when driven at high luminance (high current density) and a method for manufacturing the organic electroluminescent device.
  • EL organic electroluminescence
  • An organic EL element has a structure in which a light-emitting layer containing a compound that emits light (hereinafter also referred to as “light-emitting material”) is sandwiched between a cathode and an anode, and recombines by injecting electrons and holes into the light-emitting layer.
  • This is an element that generates excitons (excitons) by light emission, and emits light by utilizing light emission (fluorescence / phosphorescence) when the excitons are deactivated.
  • Such an organic EL element can emit light at a low voltage of several to several tens of volts, and further has a wide viewing angle and high visibility because it is a self-luminous type.
  • the organic EL element is a thin-film type complete solid-state element, it has attracted attention from the viewpoints of space saving and portability.
  • an organic EL element capable of emitting light with better luminous efficiency, luminance and chromaticity is desired.
  • organic EL devices have two types of emission methods: “phosphorescence emission” that emits light when returning from the triplet excited state to the ground state, and “fluorescence emission” that emits light when returning from the singlet excited state to the ground state. Two ways are known.
  • thermoally activated delayed fluorescence where a reverse intersystem crossing from a triplet exciton to a singlet exciton, hereinafter, also referred to as “RISC” occurs.
  • thermally excited delayed fluorescence Thermally Activated Delayed Fluorescence (hereinafter abbreviated as “TADF” where appropriate) and the possibility of use in organic EL devices has been reported (for example, (See Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2.)
  • TADF Thermally Activated Delayed Fluorescence
  • the phosphorescence and TADF methods are excellent.
  • the phosphorescence method and the TADF method still have room for improvement in terms of lifetime and color purity, especially for blue light emission, particularly pure blue or deep blue, which requires a short emission wavelength. No practically satisfactory level of color purity has been found.
  • the blue phosphorescent compound has a higher energy level (hereinafter also simply referred to as “level”) than that of red or green, and has a low level of quenching generated during electric field driving. This is because energy transfer to a substance is easy.
  • the blue phosphorescent compound has an emission decay lifetime ⁇ of about several ⁇ s to several tens of ⁇ s, which is 2 to 4 orders longer than the fluorescence lifetime of the fluorescent material.
  • the blue phosphorescent compound since the blue phosphorescent compound has a high triplet excited state level, the emission spectrum from the blue phosphorescent compound and the absorption spectrum of the quencher are likely to overlap, and the energy transfer rate is large. It has become.
  • phosphorescent compounds and TADF compounds having a long emission decay lifetime (on the order of microseconds) and TADF compounds are easily quenched by a quencher (quenching substance), and the luminance half-life of the organic EL element (hereinafter, referred to as the “luminescence half-life”). Simply referred to as “half-life”).
  • one of the factors that cause a reduction in the half-life of the organic EL element is heat generation during driving.
  • the excitation energy generated by recombination of holes and electrons in the light-emitting layer is not necessarily consumed as light emission, but part of it is deactivated as heat.
  • the released heat is accumulated in the element.
  • decomposition and aggregation of the compound contained in the organic EL element occur, quencher generation accompanying it, fluctuations in film physical properties, and the like.
  • carrier balance due to exciton quenching and film physical property fluctuations due to the quencher occurs.
  • the collapse of the brightness causes a reduction in luminance and half-life.
  • the emission efficiency of the organic EL element has been proposed to improve luminous efficiency by a method in which a phosphorescent compound and a fluorescent compound are contained in one light emitting layer.
  • a method in which a phosphorescent compound and a fluorescent compound are contained in one light emitting layer For example, refer to Patent Document 2.
  • the value of the external extraction quantum efficiency is as low as 3.3%, which does not exceed the theoretical limit value of the fluorescent light emitting device, and is not at a practical level. Also, the roll-off was great.
  • JP 2013-116975 A Japanese translation of PCT publication No. 2003-520391
  • the present invention has been made in view of the above-described problems and circumstances, and the problem to be solved is that the luminance half-life can be improved even when driven at high luminance (high current density), and the luminous efficiency is also excellent.
  • An organic electroluminescence device is provided.
  • the present inventor includes a specific phosphorescent compound and a fluorescent compound in the light emitting layer in the process of examining the cause of the above problem, and the like. Brightness is enhanced by promoting Ferster-type energy transfer to the fluorescent compound and maintaining the emission decay lifetime ⁇ of the single light emitting layer and the absolute quantum yield PLQE ( ⁇ ) of the single light emitting layer at the specified values. It has been found that even when driven at (high current density), the luminance half-life can be improved and the light emission efficiency can be improved, leading to the present invention. That is, the said subject which concerns on this invention is solved by the following means.
  • An organic electroluminescence device having a light emitting layer,
  • the light emitting layer contains a phosphorescent compound and a fluorescent compound,
  • the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap,
  • the light emission decay lifetime ⁇ of the light emitting layer satisfies the following formula (1):
  • the absolute quantum yield PLQE ⁇ of the light emitting layer single layer satisfies the following formula (2):
  • the organic electroluminescent element whose Stokes shift of the said fluorescent compound is 0.1 eV or less.
  • the excitation energy generated on the phosphorescent compound can be rapidly transferred to the fluorescent compound by Forster-type energy transfer or Dexter-type energy transfer. It can be transferred to a fluorescent compound and consumed.
  • the emission decay lifetime of the phosphorescent compound is shortened to the order of sub-microseconds to nanoseconds. Therefore, from the formula (A), quenching with respect to the quencher is difficult, and the half-life is improved.
  • TTA triplet-triplet annihilation
  • triplet-polaron exciton annihilation is less likely to occur, and roll-off is improved.
  • TPA triplet-polaron exciton annihilation
  • the present inventor has examined that, in the above-described continuous driving at a high current, the process of excitation and light emission is repeated in a state where the exciton density is high, so that the heat accumulated in the organic EL element is continuously low in current. It has been found that the conventional method of adding a fluorescent compound to a light emitting layer containing a phosphorescent compound that is larger than driving (for example, see Patent Document 2) cannot sufficiently suppress the above-described fluctuations in film properties. It was. Furthermore, when the present inventors diligently studied, by adding a compound having a small Stokes shift as a fluorescent light emitting compound, heat generation is further suppressed even at high current density driving, fluctuation of film physical properties is suppressed, and half life is reduced. I found out that I could do better. The detailed reason is described below. As a result, since the deterioration rate can be further reduced, the following half-life acceleration coefficient n can be reduced.
  • the acceleration coefficient is n in the following formula (B).
  • t 1 / t 2 (L 1 / L 2 ) ⁇ n (B) [L 1: current density 2.5 mA / cm 2 upon application of the initial luminance L 2: current density 16.25mA / cm 2 applied during the initial luminance t 1: the luminance L 1 (low current 2.5 mA / cm 2) T 2 : Half life at luminance L 2 (high current 16.25 mA / cm 2 )]
  • a small Stokes shift means a small change in molecular structure between the excited state and the ground state. This can be said that the difference between the excitation energy and the emission energy is small, that is, the energy released as heat without contributing to the emission is small (see FIG. 1A).
  • a large Stokes shift means that the energy released as heat is large because the molecular structure varies greatly between the excited state and the ground state, and the difference between the excited energy and the emitted energy is also large. (See FIG. 1B.) Therefore, by using a fluorescent compound having a small Stokes shift, generation of heat can be suppressed even in high current driving with a high exciton density, and fluctuations in film properties over time can be suppressed.
  • the excitation energy generated in the light emitting layer emits light mainly from a fluorescent compound.
  • the amount of the fluorescent light-emitting compound added is small, the excitation energy generated in the light-emitting layer is collected in the fluorescent light-emitting compound, so even if the amount added is small, it cannot be ignored as a film quality variation factor.
  • the Stokes shift of the fluorescent compound is preferably small, specifically 0.1 eV or less.
  • the inventor of the present invention has disclosed that the emission decay lifetime ⁇ of the light emitting layer single layer is shorter than the phosphorescence emission decay lifetime ⁇ 0 (Equation (1)), and the absolute quantum yield ⁇ of the light emitting layer single layer is phosphorescent. It has been found that the acceleration coefficient of the luminance half-life with respect to the applied current can be further reduced within a specific range (equation (2)) with respect to the absolute quantum yield ( ⁇ 0 ) of the single film of the active compound.
  • the phosphorescent compound emits fluorescence by transferring the excitation energy in the triplet excited state of the phosphorescent compound to the singlet excited state of the fluorescent compound.
  • Dexter energy transfer can occur from the triplet excited state of the phosphorescent compound to the triplet excited state of the fluorescent compound (FIG. 2). reference.).
  • the fluorescence emission compound is deactivated by non-luminescence from the triplet excited state, and thus the absolute quantum yield (that is, the absolute quantum yield ⁇ of the single light emitting layer) is lowered.
  • the absolute quantum yield ⁇ of the light emitting layer is higher.
  • a practical phosphorescent compound has a high absolute quantum yield close to 100% (that is, the absolute quantum yield ⁇ 0 of a single film of the phosphorescent compound), and contains a fluorescent compound.
  • the main factor for efficiently developing Forster energy transfer is to increase the overlap between the emission spectrum of the energy donor (phosphorescent compound) and the absorption spectrum of the energy acceptor (fluorescent compound). is there. Therefore, in the present invention, it is essential that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap.
  • the Forster energy transfer is inversely proportional to the sixth power of the intermolecular distance R as shown in the following equation (F).
  • Dexter type energy transfer shows exponential decay with respect to the intermolecular distance R as shown in the following equation (D) (Reference: Basic Chemistry Course, Photochemistry I Haruo Inoue, Katsuhiko Takagi, Masako Sasaki, Park Bell) Co-authored with Earthquake)
  • k ET represents the energy transfer speed.
  • the organic electroluminescent device of the present invention is an organic electroluminescent device having a light emitting layer, wherein the light emitting layer contains a phosphorescent compound and a fluorescent compound, and an emission spectrum of the phosphorescent compound and The absorption spectrum of the fluorescent compound has an overlap, the emission decay lifetime ⁇ of the single light emitting layer satisfies the above formula (1), and the absolute quantum yield PLQE ⁇ of the single light emitting layer is The above formula (2) is satisfied, and the Stokes shift of the fluorescent compound is 0.1 eV or less.
  • This feature is a technical feature common to or corresponding to the following embodiments.
  • the present invention can provide an organic electroluminescence device that can have a good luminance half-life and good luminous efficiency even when driven at high luminance (high current density).
  • the phosphorescent compound and the fluorescent compound satisfy the above formula (3) or the above formula (4), thereby keeping the external extraction efficiency (EQE) high. It is preferable because it is possible.
  • the content (% by mass) of the fluorescent compound is more than the content (% by mass) of the phosphorescent compound. Less is preferable because the external extraction quantum efficiency and the half life can be improved.
  • the content of the fluorescent light emitting compound is 5% by mass or less to improve the external extraction quantum efficiency and the half life. This is preferable because it is possible.
  • the light emitting layer can be produced by a dry process or a wet process.
  • a wet process not only can the restrictions imposed on the shape and size of the element be reduced, but also an organic electroluminescent element can be manufactured by a cheaper manufacturing process.
  • ⁇ is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
  • the organic electroluminescence device of the present invention is an organic electroluminescence device having a light emitting layer,
  • the light emitting layer contains a phosphorescent compound and a fluorescent compound,
  • the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap
  • the emission decay lifetime ⁇ of the light emitting layer single layer satisfies the following formula (1):
  • the absolute quantum yield PLQE ( ⁇ ) of the single light emitting layer satisfies the following formula (2):
  • the Stokes shift of the said fluorescent compound is 0.1 eV or less,
  • the organic electroluminescent element characterized by the above-mentioned.
  • the emission spectrum of the phosphorescent compound according to the present invention and the absorption spectrum of the fluorescent compound have an overlap.
  • the fact that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound have an overlap means that the emission spectrum of the phosphorescent compound and the absorption located on the longest wavelength side of the fluorescent compound. It means that the belt overlaps.
  • the magnitude of the overlap of each spectrum is called an overlap integral value and is calculated by the following equation (OI).
  • f D is a normalized donor (energy donor, phosphorescent compound) emission spectrum
  • ⁇ A is a molar extinction coefficient of the acceptor (energy acceptor, fluorescent compound).
  • ⁇ indicates a wavelength.
  • J represents an overlap integral value.
  • the Stokes shift of the fluorescent compound is 0.1 eV or less, and the minimum value is 0 eV.
  • the Stokes shift refers to the energy difference (or wavelength difference) between the absorption maximum and the emission fluorescence maximum.
  • the maximum absorption wavelength ⁇ abs (nm) of the absorption band on the longest wave side of the solution absorption spectrum and the maximum emission wavelength ⁇ em (nm) of the shortest wave side of the solution emission spectrum are represented by energy ( eV) and obtained from the difference.
  • the maximum absorption wavelength ⁇ abs and the maximum emission wavelength ⁇ em of the fluorescent compound can be measured using an ultraviolet-visible-infrared spectrophotometer (for example, U-570 manufactured by JASCO Corporation).
  • the temperature of each solution in the measurement of the maximum absorption wavelength ⁇ abs and the maximum emission wavelength ⁇ em is 23 ° C.
  • a practical phosphorescent compound has a high absolute quantum yield close to 100% (that is, an absolute quantum yield ⁇ 0 of a single film of the phosphorescent compound), and a fluorescent compound is added. Even It is desired to suppress a decrease in absolute quantum yield due to the above Dexter type energy transfer and maintain a high absolute quantum yield. From the above viewpoint, practical light-emitting element performance can be maintained if ⁇ / ⁇ 0 is in the range of 0.6 to 1.0. It should be noted that the maximum value of ⁇ / ⁇ 0 is 1.0 in the sense that ⁇ 0 of phosphorescence alone is maintained (does not decrease).
  • the probability that the charge injected into the light emitting layer is recombined on the phosphorescent compound is higher, and recombination is performed on the fluorescent compound. Can be suppressed. As a result, a decrease in external extraction efficiency (EQE) can be further suppressed.
  • the light emission decay lifetime of the single light emission layer may be measured by manufacturing a single film having the same structure as the light emission layer, such as a light emitting film for evaluation described later, and measuring the light emission decay lifetime of the single film.
  • the emission decay lifetime ⁇ can be measured by using a streak camera C4334 (manufactured by Hamamatsu Photonics).
  • the emission decay lifetime ⁇ 0 of the phosphorescent compound single film is the same as that of the evaluation light emitting film obtained by measuring the emission decay lifetime ⁇ except that the fluorescent emission compound is not contained. What is necessary is just to measure similarly to the light emission decay lifetime ⁇ of the light emitting layer.
  • the absolute quantum yield PLQE ( ⁇ ) of the light emitting layer is a single film having the same structure as that of the light emitting layer, such as a light-emitting film for evaluation. Can be measured. Note that PLQE can be measured by using an absolute quantum yield measuring apparatus C9920-02 (manufactured by Hamamatsu Photonics).
  • the absolute quantum yield PLQE ( ⁇ 0 ) of the phosphorescent compound single film is the absolute quantum yield P
  • a single film manufactured in the same manner except that no fluorescent light emitting compound is contained may be measured in the same manner as the light emission decay lifetime ⁇ of the light emitting layer single layer.
  • LUMO is the lowest unoccupied molecular orbital of a compound.
  • the LUMO energy level is energy in which electrons in the vacuum level fall to the LUMO of the compound and stabilize, and are defined as energy when the vacuum level is zero.
  • HOMO is the highest occupied molecular orbital of a compound.
  • the HOMO energy level is defined as a value obtained by multiplying the energy required to move electrons in the HOMO to the vacuum level by -1.
  • the light emitting layer contains a phosphorescent compound and a fluorescent compound.
  • the emission decay lifetime ⁇ of the single light emitting layer satisfies the above formula (1), and the absolute quantum yield PLQE ( ⁇ ) of the single light emitting layer satisfies the above formula (2).
  • the light emitting layer according to the present invention provides a field in which electrons and holes injected from an electrode or an adjacent layer (hereinafter also referred to as “adjacent layer”) are recombined to emit light via excitons.
  • the layer that emits light may be within the light emitting layer or at the interface between the light emitting layer and the adjacent layer.
  • the light emitting layer single layer concerning this invention means the light emitting film for evaluation produced as a spectrum measurement sample containing a host compound, a phosphorescent light emitting compound, and a fluorescent light emitting compound.
  • the specific manufacturing method of this light emitting film for evaluation will be described in detail in Examples.
  • the phosphorescent compound single film is a host compound, a phosphorescent compound, and a fluorescent compound, and includes the host compound, the phosphorescent compound, and the evaluation light emitting film.
  • the phosphorescent compound single film is a luminescent single film for evaluation for obtaining ⁇ / ⁇ 0 and ⁇ / ⁇ 0 according to the present invention, which does not contain a fluorescent compound. .
  • the light emitting layer can be a thin layer having a thickness of 30 nm or less. This is because the light emitting layer according to the present invention can achieve the effects of high efficiency and long life even when the thin layer and exciton density are high. In addition, it is preferable that the thickness of a light emitting layer is 2 nm or more.
  • phosphorescent compound can be used. Specific examples of known phosphorescent compounds that can be used in the present invention include, but are not limited to, compounds described in the following literature. Below, a blue phosphorescent compound is demonstrated as a specific example of the phosphorescent compound which can be used conveniently by this invention.
  • a blue phosphorescent compound as a specific example of the phosphorescent compound according to the present invention is a compound containing a heavy atom and capable of emitting light from a triplet excited state. As long as luminescence is observed, there is no particular limitation.
  • a blue phosphorescent compound represented by the following general formula (1) is preferable. Thereby, a blue phosphorescent compound having more exciton stability can be produced.
  • M represents Ir or Pt.
  • a 1 , A 2 , B 1 and B 2 each independently represent a carbon atom or a nitrogen atom.
  • Ring Z 1 is a 6-membered aromatic hydrocarbon ring or 5-membered or 6-membered aromatic heterocycle formed together with A 1 and A 2 , or an aromatic condensed ring containing at least one of these rings Represents.
  • Ring Z 2 represents a 5-membered or 6-membered aromatic heterocycle formed together with B 1 and B 2 , or an aromatic condensed ring containing at least one of these rings.
  • the carbon atom contained in the ring Z 1 and the ring Z 2 may be a carbene carbon atom.
  • Ring Z 1 and ring Z 2 may each independently have a substituent. By substituents of the ring Z 1 and the ring Z 2 are attached, may form a condensed ring structure, ligands each other represented by the ring Z 1 and the ring Z 2 may be linked .
  • L represents a monoanionic bidentate ligand coordinated to M and may have a substituent.
  • m represents an integer of 0-2.
  • n represents an integer of 1 to 3.
  • M + n is 3 when M is Ir, and m + n is 2 when M is Pt.
  • the ligands or Ls represented by ring Z 1 and ring Z 2 may be the same or different, and the coordination represented by ring Z 1 and ring Z 2 The child and L may be connected.
  • Ring Z 2 is preferably a 5-membered aromatic heterocycle, and at least one of B 1 and B 2 is preferably a nitrogen atom.
  • the general formula (1) is preferably represented by the following general formula (DP-1).
  • M, A 1 , A 2 , B 1 , B 2 , rings Z 1 , L, m and n are M, A 1 , A 2 , B in the general formula (1). 1 , B 2 , synonymous with rings Z 1 , L, m and n.
  • B 3 to B 5 are an atomic group forming an aromatic heterocyclic ring, and each independently represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom which may have a substituent.
  • substituents that B 3 to B 5 have include the same groups as the substituents that the ring Z 1 and the ring Z 2 have in General Formula (1).
  • the aromatic heterocycle formed by B 1 to B 5 in the general formula (DP-1) is represented by any of the following general formulas (DP-1a), (DP-1b) and (DP-1c) It is preferable.
  • * 1 represents a binding site with A 2 in the general formula (DP-1), and * 2 represents a binding site with M.
  • Rb 3 to Rb 5 represent a hydrogen atom or a substituent, and the substituent represented by Rb 3 to Rb 5 has the same meaning as the substituents of the ring Z 1 and the ring Z 2 in the general formula (1).
  • Groups. B 4 and B 5 in the general formula (DP-1a) are a carbon atom or a nitrogen atom, and more preferably at least one is a carbon atom.
  • B 3 to B 5 in the general formula (DP-1b) are carbon atoms or nitrogen atoms, and more preferably at least one is a carbon atom.
  • B 3 and B 4 in the general formula (DP-1c) are a carbon atom or a nitrogen atom, more preferably at least one is a carbon atom, and the substituents represented by Rb 3 and Rb 4 are further bonded to each other. It is more preferable that a condensed ring structure is formed, and the newly formed condensed ring structure is preferably an aromatic ring, and includes a benzimidazole ring, an imidazopyridine ring, an imidazopyrazine ring, or a purine ring. Either is preferable.
  • Rb 5 is preferably an alkyl group or an aryl group, and more preferably a phenyl group.
  • the carbon atoms of the ring Z 1 and the ring Z 2 are carbene carbon atoms (specifically, when they are carbene complexes), for example, WO 2005 / No. 0193373, International Publication No. 2006/056418, International Publication No. 2005/113704, International Publication No. 2007/115970, International Publication No. 2007/1155981, and International Publication No. 2008/000727.
  • the carbene complex is preferably used.
  • blue phosphorescent compounds and other color phosphorescent compounds that can be used in the present invention can be appropriately selected from known compounds used in the light emitting layer of an organic EL device.
  • Specific examples of known blue phosphorescent compounds and other color phosphorescent compounds that can be used in the present invention include compounds described in the following documents, but are not limited thereto. Absent. Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chem. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Publication No.
  • Patent Publication No. 2003/0152802 U.S. Patent No. 7090928, Angew. Chem. lnt. Ed. 47, 1 (2008), Chem. Mater. 18, 5119 (2006), Inorg. Chem. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 2006/082742, US Patent Publication No.
  • the fluorescent compound according to the present invention is a compound that can emit light from a singlet excited state, satisfies the formulas (1) and (2) as long as light emission from the singlet excited state is observed, and There is no particular limitation as long as the Stokes shift is 0.1 eV or less.
  • Examples of the fluorescent compound include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarin derivatives, pyran. Derivatives, cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, rare earth complex compounds, and the like.
  • luminescent compound using delayed fluorescence include, for example, the compounds described in International Publication No. 2011/156793, Japanese Patent Application Laid-Open No. 2011-213643, Japanese Patent Application Laid-Open No. 2010-93181, and the like. Is not limited to these.
  • the content of the fluorescent compound When the content of the fluorescent compound is large, the light emission decay lifetime of the light emitting layer single layer becomes small, but the decrease in absolute quantum yield becomes remarkable. Therefore, it is preferable that the content is small. This is considered as follows. When the content of the fluorescent compound increases, the intermolecular distance between the phosphorescent compound and the fluorescent compound decreases, and the triplet of the fluorescent compound is lower than the triplet excited state of the phosphorescent compound. Since the Dexter-type energy transfer to the excited state increases, the absolute quantum yield decreases significantly (see FIG. 2). For this reason, the addition amount of the fluorescent compound is preferably small.
  • the content (% by mass) of the fluorescent compound is the phosphorous. Less than the content (% by mass) of the photoluminescent compound is preferable because the external extraction quantum efficiency and the half-life can be improved.
  • the content of the fluorescent compound is 5% by mass. The following is preferable.
  • the content is preferably 5% by mass or less, more preferably 0.9% by mass or less, and the lower limit is the absolute quantum yield of the single light emitting layer. From the viewpoint of maintaining a high rate, the smaller the content, the better. Thereby, an absolute quantum yield can be made favorable and by extension, external extraction quantum efficiency and a half life can be made more favorable.
  • the light emitting layer according to the present invention preferably contains a host compound in addition to the fluorescent compound and the phosphorescent compound.
  • the host compound according to the present invention is a compound mainly responsible for charge injection and transport in the light-emitting layer, and light emission itself is not substantially observed in the organic EL element.
  • the host compound is preferably a compound having a phosphorescence quantum yield of phosphorescence of less than 0.1 at room temperature (25 ° C.), and more preferably a compound having a phosphorescence quantum yield of less than 0.01.
  • the excited state energy of the host compound is preferably higher than the excited state energy of the phosphorescent compound contained in the same layer.
  • known host compounds may be used alone or in combination. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient.
  • the compound conventionally used with an organic EL element can be used. It may be a low molecular compound or a high molecular compound having a repeating unit, or a compound having a reactive group such as a vinyl group or an epoxy group.
  • known host compounds while having a hole transporting ability or an electron transporting ability, the emission of light is prevented from being increased in wavelength, and further, the organic EL element is stable against heat generation during high temperature driving or driving of the element.
  • Tg glass transition temperature
  • Tg is preferably 90 ° C. or higher, more preferably 120 ° C. or higher.
  • the glass transition point (Tg) is a value determined by a method based on JIS-K-7121 using DSC (Differential Scanning Calorimetry).
  • the host compound according to the present invention is preferably a compound having a structure represented by the following general formula (HA) or (HB).
  • Xa represents O or S.
  • Xb, Xc, Xd and Xe each independently represent a hydrogen atom, a substituent or a group having a structure represented by the following general formula (HC), and at least one of Xb, Xc, Xd and Xe is A group having a structure represented by the following general formula (HC) is represented, and at least one of the groups having a structure represented by the following general formula (HC) is a carbazolyl group.
  • L ′ represents a divalent linking group derived from an aromatic hydrocarbon ring or an aromatic heterocyclic ring.
  • n represents an integer of 0 to 3, and when n is 2 or more, a plurality of L ′ may be the same or different.
  • * Represents a binding site with the general formula (HA) or (HB).
  • Ar represents a group having a structure represented by the following general formula (HD).
  • Xf represents N (R ′), O or S.
  • E 1 to E 8 each represent C (R ′′) or N, and R ′ and R ′′ each represent a hydrogen atom, a substituent, or a bonding site with L ′ in the general formula (HC).
  • * Represents a binding site with L ′ in the general formula (HC).
  • Xb, Xc, Xd and Xe are represented by the general formula (HC), and more preferably Xc is represented by the general formula (HC).
  • Ar in the general formula (HC) represents a carbazolyl group which may have a substituent.
  • Examples of the substituents represented by Xb, Xc, Xd and Xe in the general formulas (HA) and (HB) and the substituents represented by R ′ and R ′′ in the general formula (HD) include the above general formula (DP ) And the same substituents that the ring Z1 and ring Z2 may have.
  • Examples of the aromatic hydrocarbon ring represented by L ′ in the general formula (HC) include a benzene ring, a p-chlorobenzene ring, a mesitylene ring, a toluene ring, a xylene ring, a naphthalene ring, an anthracene ring, an azulene ring, and an acenaphthene ring.
  • Examples of the aromatic heterocycle represented by L ′ in the general formula (HC) include a furan ring, a thiophene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazole ring, an imidazole ring, a pyrazole ring, and a thiazole ring.
  • host compound according to the present invention include compounds applicable to the present invention in addition to the compound having the structure represented by the general formula (HA) or (HB). It is not specifically limited to.
  • JP-A-2015-38941 can also be suitably used.
  • the host compound used in the present invention may be used in an adjacent layer adjacent to the light emitting layer.
  • the light emitting layer according to the present invention is composed of a single layer or a plurality of layers, and when there are a plurality of light emitting layers, a non-light emitting intermediate layer may be provided between the light emitting layers.
  • a hole blocking layer also referred to as a hole blocking layer
  • an electron injection layer also referred to as a cathode buffer layer
  • An electron blocking layer also referred to as an electron barrier layer
  • a hole injection layer also referred to as an anode buffer layer
  • the electron transport layer according to the present invention is a layer having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. Moreover, you may be comprised by multiple layers.
  • the hole transport layer according to the present invention is a layer having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. Moreover, you may be comprised by multiple layers.
  • the layer excluding the anode and the cathode is also referred to as “organic layer”.
  • the organic EL element according to the present invention may be an element having a so-called tandem structure in which a plurality of light emitting units including at least one light emitting layer are stacked.
  • first light emitting unit / second light emitting unit / third light emitting unit / cathode Anode / first light emitting unit / intermediate layer / second light emitting unit / intermediate layer / third light emitting unit / cathode
  • first light emitting unit The second light emitting unit and the third light emitting unit may all be the same or different. Two light emitting units may be the same, and the remaining one may be different.
  • the third light emitting unit may not be provided, and on the other hand, a light emitting unit or an intermediate layer may be further provided between the third light emitting unit and the electrode.
  • a plurality of light emitting units may be laminated directly or via an intermediate layer, and the intermediate layer is generally an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, an intermediate layer.
  • a known material structure can be used as long as it is also called an insulating layer and has a function of supplying electrons to the anode-side adjacent layer and holes to the cathode-side adjacent layer.
  • Examples of the material used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO 2 , TiN, ZrN, HfN, TiO x , VO x , Conductive inorganic compound layers such as CuI, InN, GaN, CuAlO 2 , CuGaO 2 , SrCu 2 O 2 , LaB 6 , RuO 2 and Al, two-layer films such as Au / Bi 2 O 3 , SnO 2 / Ag / Sn O 2 , ZnO / Ag / ZnO, Bi 2 O 3 / Au / Bi 2 O 3 , TiO 2 / TiN / TiO 2 , TiO 2 / ZrN / TiO 2 and other multilayer films, C 60 and other fullerenes, conductive organic layers such as oligothiophene, metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, metal-free porphyrins
  • Preferred examples of the configuration within the light emitting unit include, for example, those obtained by removing the anode and the cathode from the configurations (1) to (7) mentioned in the above representative device configurations, but the present invention is not limited to these. Not.
  • tandem organic EL element examples include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, US Pat. No. 6,872,472, US Pat. No. 6,107,734. Specification, U.S. Pat. No. 6,337,492, International Publication No.
  • JP-A-2006-228712 JP-A-2006-24791, JP-A-2006-49393, JP-A-2006-49394 JP-A-2006-49396, JP-A-2011-96679, JP-A-2005-340187, JP-A-4711424, JP-A-34968681, JP-A-3884564, JP-A-42131169, JP-A-2010-192719.
  • Examples include constituent materials, but the present invention is not limited to these.
  • the electron transport layer is made of a material having a function of transporting electrons, and may have a function of transmitting electrons injected from the cathode to the light emitting layer.
  • the total thickness of the electron transport layer according to the present invention is not particularly limited, but is usually in the range of 2 nm to 5 ⁇ m, more preferably 2 to 500 nm, and further preferably 5 to 200 nm.
  • the organic EL element when the light generated in the light emitting layer is extracted from the electrode, the light extracted directly from the light emitting layer interferes with the light extracted after being reflected by the electrode from which the light is extracted and the electrode located at the counter electrode. It is known to wake up. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total thickness of the electron transport layer between 5 nm and 1 ⁇ m.
  • the electron mobility of the electron transport layer is preferably 10 ⁇ 5 cm 2 / Vs or more.
  • the material used for the electron transport layer may be any of electron injecting or transporting properties and hole blocking properties, and can be selected from conventionally known compounds. Can be selected and used.
  • nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring are substituted with nitrogen atoms), pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, pyridazine derivatives, Triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, azatriphenylene derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, etc.), dibenzofuran derivatives, And dibenzothiophene derivatives, silole derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene, etc.)
  • a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand such as tris (8-quinolinol) aluminum (Alq), 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) aluminum, bis (8-quinolinol) zinc (Znq), etc.
  • a metal complex in which the central metal is replaced with In, Mg, Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material.
  • metal-free or metal phthalocyanine or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material.
  • known distyrylpyrazine derivatives used for the light emitting layer can also be used as an electron transporting material, and inorganic materials such as n-type-Si and n-type-SiC can be used as well as the hole injection layer and the hole transport layer.
  • a semiconductor can also be used as an electron transport material.
  • a polymer material in which these materials are introduced into a polymer chain or these materials as a polymer main chain can be used.
  • the electron transport layer may be doped with a doping material as a guest material to form an electron transport layer having a high n property (electron rich).
  • the doping material include n-type dopants such as metal complexes and metal compounds such as metal halides.
  • Specific examples of the electron transport layer having such a structure include, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004) and the like.
  • More preferable electron transport materials in the present invention include pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, and benzimidazole derivatives.
  • the electron transport material may be used alone or in combination of two or more.
  • the hole blocking layer is a layer having a function of an electron transport layer in a broad sense, and is preferably made of a material having a function of transporting electrons and a small ability to transport holes, and transporting electrons while transporting holes. The probability of recombination of electrons and holes can be improved by blocking.
  • the structure of the electron transport layer described above can be used as a hole blocking layer according to the present invention, if necessary.
  • the hole blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the cathode side of the light emitting layer.
  • the thickness of the hole blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
  • the material used for the hole blocking layer As the material used for the hole blocking layer, the material used for the above-described electron transport layer is preferably used, and the above-described host compound according to the present invention and other materials used as the host compound are also used for the hole blocking layer. Preferably used.
  • the electron injection layer (also referred to as “cathode buffer layer”) according to the present invention is a layer provided between the cathode and the light emitting layer in order to lower the driving voltage and improve the light emission luminance. It is described in detail in Chapter 2 “Electrode Materials” (pages 123 to 166) of the second edition of “The Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
  • the electron injection layer may be provided as necessary, and may be present between the cathode and the light emitting layer or between the cathode and the electron transport layer as described above.
  • the electron injection layer is preferably a very thin film, and the thickness is preferably in the range of 0.1 to 5 nm, depending on the material. Moreover, the nonuniform film
  • JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like Specific examples of materials preferably used for the electron injection layer are as follows. , Metals typified by strontium and aluminum, alkali metal compounds typified by lithium fluoride, sodium fluoride, potassium fluoride, etc., alkaline earth metal compounds typified by magnesium fluoride, calcium fluoride, etc., oxidation Examples thereof include metal oxides typified by aluminum, metal complexes typified by lithium 8-hydroxyquinolate (Liq), and the like. Further, the above-described electron transport material can also be used.
  • the materials used for the electron injection layer may be used alone or in combination of two or more.
  • the hole transport layer is made of a material having a function of transporting holes and may have a function of transmitting holes injected from the anode to the light emitting layer.
  • the total thickness of the hole transport layer according to the present invention is not particularly limited, but is usually in the range of 5 nm to 5 ⁇ m, more preferably 2 to 500 nm, and further preferably 5 nm to 200 nm.
  • a material used for the hole transport layer (hereinafter referred to as a hole transport material), any material that has either a hole injection property or a transport property or an electron barrier property may be used. Any one can be selected and used.
  • porphyrin derivatives for example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stilbene derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinyl carbazole, polymer materials or oligomers with aromatic amines introduced into the main chain or side chain, polysilane, conductive And polymer (for example, PEDOT: PSS, aniline copolymer, polyaniline, polythiophene, etc.).
  • PEDOT PSS, aniline copolymer, polyaniline
  • triarylamine derivatives examples include benzidine type typified by ⁇ -NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl), starburst type typified by MTDATA, Examples include compounds having fluorene or anthracene in the triarylamine-linked core.
  • hexaazatriphenylene derivatives such as those described in JP-T-2003-519432 and JP-A-2006-135145 can also be used as a hole transport material.
  • a hole transport layer having a high p property doped with impurities can also be used.
  • examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.
  • the above-mentioned materials can be used as the hole transport material, but a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, or an aromatic amine is introduced into the main chain or side chain.
  • the polymer materials or oligomers used are preferably used.
  • preferable hole transport materials used in the organic EL device of the present invention include, but are not limited to, the compounds described in the following documents in addition to the documents listed above.
  • the hole transport material may be used alone or in combination of two or more.
  • the electron blocking layer is a layer having a function of a hole transport layer in a broad sense, and is preferably made of a material having a function of transporting holes and a small ability to transport electrons, and transporting electrons while transporting holes. The probability of recombination of electrons and holes can be improved by blocking.
  • the above-described configuration of the hole transport layer can be used as an electron blocking layer according to the present invention, if necessary.
  • the electron blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the anode side of the light emitting layer.
  • the thickness of the electron blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
  • the material used for the electron blocking layer As the material used for the electron blocking layer, the material used for the above-described hole transport layer is preferably used, and the above-described host compound according to the present invention and other materials used as the host compound are also preferable for the electron blocking layer. Used.
  • the hole injection layer (also referred to as “anode buffer layer”) according to the present invention is a layer provided between the anode and the light emitting layer for the purpose of lowering the driving voltage and improving the light emission luminance. It is described in detail in Volume 2, Chapter 2, “Electrode Materials” (pages 123 to 166) of “The Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
  • the hole injection layer may be provided as necessary, and may be present between the anode and the light emitting layer or between the anode and the hole transport layer as described above.
  • the details of the hole injection layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, etc.
  • Examples of materials used for the hole injection layer include: Examples thereof include materials used for the above-described hole transport layer.
  • phthalocyanine derivatives typified by copper phthalocyanine, hexaazatriphenylene derivatives, metal oxides typified by vanadium oxide, amorphous carbon as described in JP-T-2003-519432, JP-A-2006-135145, etc.
  • the materials used for the hole injection layer described above may be used alone or in combination of two or more.
  • the organic layer in the present invention described above may further contain other additives.
  • halogen elements and halogenated compounds such as bromine, iodine and chlorine, alkali metals and alkaline earth metals such as Pd, Ca and Na, transition metal compounds, complexes and salts.
  • the content of other additives can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, and still more preferably 50 ppm or less, based on the total mass% of the contained layer. It is.
  • ⁇ Method of forming organic layer ⁇ As a method for producing the organic electroluminescence device according to the present invention, a known method can be suitably employed.
  • the light-emitting layer may be formed using a wet process or a dry process. preferable.
  • a method for forming an organic layer (hole injection layer, hole transport layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) will be described below.
  • the method for forming the organic layer is not particularly limited, and conventionally known methods such as a vacuum deposition method such as a dry process, a wet process, and the like can be used.
  • the organic layer may be formed by using a wet process or a dry process.
  • the organic layer is preferably a layer formed by a wet process. That is, it is preferable to produce an organic EL element by a wet process.
  • a uniform film (coating film) can be easily obtained, and effects such as the difficulty of generating pinholes can be achieved.
  • membrane (coating film) here is a thing of the state dried after application
  • Examples of the wet process include spin coating, casting, ink jet, printing, die coating, blade coating, roll coating, spray coating, curtain coating, and LB (Langmuir-Blodgett). From the viewpoint of obtaining a homogeneous thin film easily and high productivity, a method with high roll-to-roll method suitability such as a die coating method, a roll coating method, an ink jet method, and a spray coating method is preferable.
  • dry process examples include vapor deposition methods (resistance heating, EB method, etc.), sputtering methods, CVD methods, and the like.
  • liquid medium for dissolving or dispersing the material of the organic EL device examples include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene and xylene.
  • Aromatic hydrocarbons such as mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO can be used.
  • a dispersion method it can be dispersed by a dispersion method such as ultrasonic wave, high shearing force dispersion or media dispersion.
  • vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a degree of vacuum of 10 ⁇ 6 to 10 ⁇ 2 Pa, and a vapor deposition rate of 0.01 to It is desirable to select appropriately within a range of 50 nm / second, a substrate temperature of ⁇ 50 to 300 ° C., and a thickness of 0.1 nm to 5 ⁇ m, preferably 5 to 200 nm.
  • the organic layer according to the present invention it is preferable to consistently produce from the hole injection layer to the cathode by a single evacuation, but it may be taken out halfway and subjected to different film forming methods. In that case, it is preferable to perform the work in a dry inert gas atmosphere.
  • anode in the organic EL element those having a work function (4 eV or more, preferably 4.5 V or more) of a metal, an alloy, an electrically conductive compound and a mixture thereof as an electrode material are preferably used.
  • electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO 2 , and ZnO.
  • conductive transparent materials such as CuI, indium tin oxide (ITO), SnO 2 , and ZnO.
  • an amorphous material such as IDIXO (In 2 O 3 —ZnO) that can form a transparent conductive film may be used.
  • these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern of a desired shape may be formed by a photolithography method, or when pattern accuracy is not so required (about 100 ⁇ m or more) A pattern may be formed through a mask having a desired shape during the vapor deposition or sputtering of the electrode material.
  • a wet film forming method such as a printing method or a coating method can also be used.
  • the transmittance be greater than 10%, and the sheet resistance as the anode is several hundred ⁇ / sq. The following is preferred.
  • the thickness of the anode depends on the material, but is usually selected in the range of 10 nm to 1 ⁇ m, preferably 10 to 200 nm.
  • Electrode a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used.
  • electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3 ) Mixtures, indium, lithium / aluminum mixtures, aluminum, rare earth metals and the like.
  • a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this for example, a magnesium / silver mixture
  • a magnesium / aluminum mixture a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al 2 O 3 ) mixture, a lithium / aluminum mixture, aluminum and the like.
  • the cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
  • the sheet resistance as a cathode is several hundred ⁇ / sq. The following is preferable, and the thickness is usually selected in the range of 10 nm to 5 ⁇ m, preferably 50 to 200 nm.
  • the emission luminance is improved, which is convenient.
  • a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a thickness of 1 to 20 nm.
  • the support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.
  • polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic, or polyarylate, Arton (trade name, manufactured by JSR) or Appel (
  • the surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ⁇ 0.5 ° C.) measured by a method according to JIS K 7129-1992. And a relative humidity (90 ⁇ 2)% RH) of 0.01 g / (m 2 ⁇ 24 h) or less is preferable, and oxygen measured by a method in accordance with JIS K 7126-1987
  • a high barrier film having a permeability of 10 ⁇ 3 mL / (m 2 ⁇ 24 h ⁇ atm) or less and a water vapor permeability of 10 ⁇ 5 g / (m 2 ⁇ 24 h) or less is preferable.
  • the material for forming the barrier film may be any material that has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen.
  • silicon oxide, silicon dioxide, silicon nitride, or the like can be used.
  • the method for forming the barrier film is not particularly limited.
  • vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
  • the opaque support substrate examples include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.
  • the external extraction quantum efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, and more preferably 5% or more.
  • the external extraction quantum efficiency (%) the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element ⁇ 100.
  • a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination.
  • sealing means used for sealing the organic EL element of the present invention include a method of bonding a sealing member, an electrode, and a support substrate with an adhesive.
  • a sealing member it should just be arrange
  • transparency and electrical insulation are not particularly limited.
  • Specific examples include a glass plate, a polymer plate / film, and a metal plate / film.
  • the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
  • the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.
  • the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.
  • a polymer film and a metal film can be preferably used because the organic EL element can be thinned.
  • the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 ⁇ 10 ⁇ 3 mL / (m 2 ⁇ 24 h ⁇ atm) or less, and a method according to JIS K 7129-1992.
  • the measured water vapor permeability (25 ⁇ 0.5 ° C., relative humidity (90 ⁇ 2)%) is preferably 1 ⁇ 10 ⁇ 3 g / (m 2 ⁇ 24 h) or less.
  • sealing member For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.
  • the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to.
  • hot-melt type polyamide, polyester, and polyolefin can be mentioned.
  • a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
  • an organic EL element may deteriorate by heat processing, what can be adhesively cured from room temperature to 80 ° C. is preferable.
  • a desiccant may be dispersed in the adhesive.
  • coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
  • the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film.
  • the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen.
  • silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.
  • a laminated structure of these inorganic layers and layers made of organic materials it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials.
  • the method of forming these films There are no particular limitations on the method of forming these films. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.
  • an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase.
  • a vacuum can also be used.
  • a hygroscopic compound can also be enclosed inside.
  • hygroscopic compound examples include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate).
  • metal oxides for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide
  • sulfates for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate.
  • metal halides eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.
  • perchloric acids eg perchloric acid Barium, magnesium perchlorate, and the like
  • anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.
  • a protective film or a protective plate may be provided outside the sealing film or the sealing film on the side facing the support substrate with the organic layer interposed therebetween.
  • the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate.
  • the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, but the polymer film is light and thin. Is preferably used.
  • An organic electroluminescent element emits light inside a layer having a refractive index higher than that of air (with a refractive index of about 1.6 to 2.1), and about 15% to 20% of light generated in the light emitting layer. It is generally said that only light can be extracted. This is because light incident on the interface (interface between the transparent substrate and air) at an angle ⁇ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the side surface of the device.
  • a technique for improving the light extraction efficiency for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the transparent substrate and the air interface (for example, US Pat. No. 4,774,435), A method for improving efficiency by providing light condensing property (for example, Japanese Patent Laid-Open No. 63-134795), a method for forming a reflective surface on the side surface of an element (for example, Japanese Patent Laid-Open No. 1-220394), a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (for example, Japanese Patent Laid-Open No.
  • the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.
  • the low refractive index layer examples include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally in the range of about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.
  • the thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low-refractive index layer is reduced when the thickness of the low-refractive index medium is about the wavelength of light and the electromagnetic wave exuded by evanescent enters the substrate.
  • the method of introducing a diffraction grating into an interface that causes total reflection or in any medium has a feature that the effect of improving the light extraction efficiency is high.
  • This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction, such as first-order diffraction or second-order diffraction.
  • the light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating into any layer or medium (in the transparent substrate or transparent electrode). , Trying to extract light out.
  • the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. The light extraction efficiency does not increase so much.
  • the refractive index distribution a two-dimensional distribution
  • the light traveling in all directions is diffracted, and the light extraction efficiency is increased.
  • the position where the diffraction grating is introduced may be in any layer or in the medium (in the transparent substrate or the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.
  • the period of the diffraction grating is preferably in the range of about 1/2 to 3 times the wavelength of light in the medium.
  • the arrangement of the diffraction grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.
  • the organic EL element of the present invention is processed to provide a structure on a microlens array, for example, on the light extraction side of the support substrate (substrate), or combined with a so-called condensing sheet, so that a specific direction, For example, the luminance in a specific direction can be increased by condensing light in the front direction with respect to the element light emitting surface.
  • a quadrangular pyramid having a side of 30 ⁇ m and an apex angle of 90 degrees is arranged two-dimensionally on the light extraction side of the substrate.
  • One side is preferably within a range of 10 to 100 ⁇ m. If it is smaller than this, the effect of diffraction is generated and colored, and if it is too large, the thickness becomes thick, which is not preferable.
  • the condensing sheet it is possible to use, for example, an LED backlight of a liquid crystal display device that has been put into practical use.
  • a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used.
  • BEF brightness enhancement film
  • a substrate may be formed with a ⁇ -shaped stripe having an apex angle of 90 degrees and a pitch of 50 ⁇ m, or the apex angle is rounded and the pitch is changed randomly. Other shapes may also be used.
  • a light diffusion plate / film may be used in combination with the light collecting sheet.
  • a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.
  • the organic EL element of the present invention can be used as a display device, a display, and various light emission sources.
  • lighting devices home lighting, interior lighting
  • clock and liquid crystal backlights billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light
  • the light source of a sensor etc. are mentioned, It is not limited to this, Especially, it can use effectively for the use as a backlight of a liquid crystal display device, and a light source for illumination.
  • patterning may be performed by a metal mask, an ink jet printing method, or the like when forming a film, if necessary.
  • patterning only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned.
  • a conventionally known method is used. Can do.
  • FIG. 3 is a schematic perspective view showing an example of a configuration of a display device including the organic EL element of the present invention, and displays image information by light emission of the organic EL element, for example, a display such as a mobile phone FIG.
  • the display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.
  • Control unit B is electrically connected to display unit A.
  • the control unit B sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside.
  • each pixel sequentially emits light according to the image data signal for each scanning line by the scanning signal, and the image information is displayed on the display unit A.
  • FIG. 4 is a schematic diagram of the display unit A shown in FIG.
  • the display unit A has a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate.
  • the main components of the display unit A will be described below.
  • FIG. 4 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).
  • Each of the scanning lines 5 and the plurality of data lines 6 in the wiring portion is made of a conductive material.
  • the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at the orthogonal positions (details are not shown).
  • the pixel 3 When the scanning signal is transmitted from the scanning line 5, the pixel 3 receives the image data signal from the data line 6 and emits light according to the received image data.
  • a full-color display is possible by arranging pixels in the red region, the green region, and the blue region as appropriate in parallel on the same substrate.
  • the non-light emitting surface of the organic EL device of the present invention is covered with a glass case, a 300 ⁇ m thick glass substrate is used as a sealing substrate, and an epoxy photocurable adhesive (LUX The track LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured, sealed, and illuminated as shown in FIGS.
  • a device can be formed.
  • FIG. 5 shows a schematic diagram of a lighting device, and the organic EL element 101 of the present invention is covered with a glass cover 102 (in addition, the sealing operation with the glass cover is to bring the organic EL element 101 into contact with the atmosphere.
  • a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or higher).
  • FIG. 6 shows a cross-sectional view of the lighting device.
  • 105 denotes a cathode
  • 106 denotes an organic EL layer (light emitting unit)
  • 107 denotes a glass substrate with a transparent electrode.
  • the glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.
  • Example 1 [Production of Organic EL Elements 1-1 to 1-12] (Preparation of base material) A transparent substrate with an ITO (Indium Tin Oxide) film having a thickness of 150 nm formed on a glass substrate of 50 mm ⁇ 50 mm and a thickness of 0.7 mm, patterned, and this ITO transparent electrode was attached was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.
  • ITO Indium Tin Oxide
  • This transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
  • Each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication.
  • As the evaporation crucible a crucible made of a resistance heating material made of molybdenum or tungsten was used.
  • the compound of the light emitting layer was changed to 84.5% by volume, 15% by volume, and 0.5% by volume of the host compound H-1, the phosphorescent compound PD-1, and the fluorescent compound described in Table I, respectively.
  • it was co-deposited on the hole transport layer at a deposition rate of 0.06 nm / second to form a light emitting layer having a thickness of 30 nm.
  • the compound ALq3 was deposited thereon at a deposition rate of 0.1 nm / second to form an electron transport layer having a thickness of 30 nm.
  • the non-light-emitting surface side of the element on which the cathode is formed is covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more, and an electrode lead-out wiring is installed. 1 to 1-12 were produced.
  • a quartz substrate having a size of 50 mm ⁇ 50 mm and a thickness of 0.7 mm is ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.
  • the transparent substrate is then used as a substrate holder for a commercially available vacuum deposition apparatus. Fixed to.
  • the host compound H-1, the phosphorescent compound PD-1, and the respective fluorescent compounds used in the organic EL elements 1-1 to 1-12 were prepared. It filled so that it might become the amount similar to the case of this time.
  • the evaporation crucible used was made of a resistance heating material made of molybdenum. After depressurizing the inside of the vacuum evaporation system to a vacuum degree of 1 ⁇ 10 ⁇ 4 Pa, the host compound, phosphorescent compound, and fluorescent compound were 84.5% by volume, 15% by volume, and 0.5% by volume, respectively. In this way, vapor deposition was performed at a vapor deposition rate of 0.06 nm / second to prepare evaluation light-emitting films 1-1 to 1-12 having a film thickness of 30 nm.
  • the types of “host compounds”, “phosphorescent compounds” and “fluorescent compounds” contained in the evaluation light-emitting films 1-1 to 1-12, and the concentrations of the respective compounds are as follows. This corresponds to the elements 1-1 to 1-12.
  • a single film composed of the phosphorescent compound PD-1 and the host compound H-1 in the same manner except that no fluorescent compound is contained (
  • the phosphorescent compound single film PD-1 was produced by changing the content of the phosphorescent compound and increasing the host compound by the amount not containing the fluorescent compound.
  • the measurement of the solution absorption spectrum (maximum absorption wavelength ⁇ abs ) of the fluorescent compound was performed as follows. First, the fluorescent compound was dissolved in 2-methyltetrahydrofuran (2m-THF) (without stabilizer) to obtain a solution having a concentration of 1.0 ⁇ 10 ⁇ 5 mol / L. The obtained solution was put into a quartz cell (10 mm long square cell), and the absorbance in the wavelength region of 250 to 700 nm of the solution was measured using a spectrophotometer (HITACHI U-3300 spectrophotometer) (liquid). The temperature was 23 ° C.).
  • 2m-THF 2-methyltetrahydrofuran
  • the emission decay lifetime ⁇ and the emission decay lifetime ⁇ 0 were measured as follows, and ⁇ / ⁇ 0 was obtained.
  • the light emission decay lifetime ⁇ of the evaluation light emitting films 1-1 to 1-12 was measured. Specifically, the emission decay lifetimes ⁇ of the evaluation light-emitting films 1-1 to 1-12 were obtained by measuring transient PL characteristics.
  • a small fluorescent lifetime measuring device C11367-03 manufactured by Hamamatsu Photonics was used for measurement of transient PL characteristics. The attenuation component was measured in TCC900 mode using an 280 nm LED as an excitation light source.
  • Luminescence decay lifetime ⁇ 0 A light emission decay lifetime ⁇ 0 is obtained in the same manner as the measurement of the light emission decay lifetime ⁇ , except that the phosphorescent compound single film PD-1 is used instead of the evaluation light emission membrane 1-1 to 1-12. It was measured.
  • the absolute quantum yield PLQE ( ⁇ ) of the light-emitting films for evaluation 1-1 to 1-12 corresponding to the organic EL elements 1-1 to 1-12 was measured using an absolute quantum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics). ).
  • the measurement of the maximum emission wavelength ⁇ em of the fluorescent compound was performed as follows. First, the fluorescent compound was dissolved in 2-methyltetrahydrofuran (2m-THF) to prepare 1 ⁇ 10 ⁇ 5 mol / L 2m-THF solution. The obtained solution was bubbled with nitrogen gas (N 2 ) for 10 minutes and then measured using a fluorometer (HITACHI F-7000) (liquid temperature was 23 ° C.). In the measurement, an emission spectrum was measured using the maximum absorption wavelength as excitation light, and the maximum maximum emission wavelength in the emission spectrum was defined as the maximum emission wavelength ⁇ em . When there are a plurality of emission peaks in the above wavelength range, the peak at the shortest wavelength side is defined as the emission peak.
  • the criteria for determining the half-life acceleration factor are as follows. ⁇ : Less than 1.4 (pass) ⁇ : 1.4 or more and less than 1.6 (failed) X: 1.6 or more (failed)
  • Example 2 [Production of Organic EL Elements 2-1 to 2-11] (Preparation of base material) A transparent substrate with an ITO (Indium Tin Oxide) film having a thickness of 150 nm formed on a glass substrate of 50 mm ⁇ 50 mm and a thickness of 0.7 mm, patterned, and this ITO transparent electrode was attached was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.
  • ITO Indium Tin Oxide
  • this transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
  • Each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication.
  • the crucible for vapor deposition used what was produced with the resistance heating material made from molybdenum.
  • the pressure was reduced to 1 ⁇ 10 ⁇ 4 Pa, heated by energizing a deposition crucible containing ⁇ -NPD, and deposited on the hole injection layer at a deposition rate of 0.1 nm / sec.
  • the hole transport layer was formed.
  • HB-1 was deposited on the light emitting layer at a deposition rate of 0.1 nm / second to form a 10 nm thick hole blocking layer.
  • Compound ET-1 was deposited on the hole blocking layer at a deposition rate of 0.1 nm / second to form an electron transport layer having a thickness of 30 nm.
  • the organic EL elements 2-2 and 2-6 had a Stokes shift of the fluorescent compound having a value larger than 0.1 eV.
  • the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound overlap, and the Stokes shift of the fluorescent compound is 0.1 eV. It was the following.
  • Example 3 [Production of Organic EL Elements 3-1 to 3-16] (Preparation of base material) First, an atmospheric pressure plasma discharge treatment having a configuration described in Japanese Patent Application Laid-Open No. 2004-68143 is formed on the entire surface of a polyethylene naphthalate film (hereinafter abbreviated as PEN) (manufactured by Teijin DuPont Films Ltd.) on the anode forming side. Using an apparatus, an inorganic gas barrier layer made of SiOx was formed to a thickness of 500 nm.
  • PEN polyethylene naphthalate film
  • a flexible base material having a gas barrier property with an oxygen permeability of 0.001 mL / (m 2 ⁇ 24 h) or less and a water vapor permeability of 0.001 g / (m 2 ⁇ 24 h) or less was produced.
  • ITO indium tin oxide
  • the base material on which the hole injection layer was formed was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and a coating liquid for forming a hole transport layer having the following composition was used to form a 5 m / After being applied for min and air-dried, it was kept at 130 ° C. for 30 minutes to form a 30 nm-thick hole transport layer.
  • nitrogen gas grade G1
  • the base material on which the hole transport layer was formed was applied at a coating speed of 5 m / min by a die coating method using a coating solution for forming a light emitting layer having the following composition, and naturally dried, and then 30 ° C. at 30 ° C. Holding for 5 minutes, a light emitting layer having a thickness of 50 nm was formed.
  • x is the concentration of the fluorescent compound shown in Table IV.
  • Host compound H-2 8.5-part by mass Phosphorescent compound PD-1 1.5 parts by mass Fluorescent compound shown in Table IV x parts by mass Isopropyl acetate 2000 parts by mass
  • the base material on which the light-emitting layer is formed is applied at a coating speed of 5 m / min by a die coating method using a coating solution for forming a hole blocking layer having the following composition, and is naturally dried, and then at 80 ° C. for 30 minutes.
  • the hole blocking layer having a thickness of 10 nm was formed.
  • the base material on which the hole blocking layer was formed was applied at a coating speed of 5 m / min by a die coating method using a coating liquid for forming an electron transport layer having the following composition, naturally dried, and then 30 ° C. at 30 ° C. Holding for 30 minutes, an electron transport layer having a thickness of 30 nm was formed.
  • ⁇ Coating liquid for electron transport layer formation > ET-1 6 parts by mass 1H, 1H, 3H-tetrafluoropropanol (TFPO) 2000 parts by mass
  • the substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. Further, a molybdenum resistance heating boat containing sodium fluoride and potassium fluoride was attached to a vacuum vapor deposition apparatus, and the vacuum chamber was depressurized to 4 ⁇ 10 ⁇ 5 Pa. Thereafter, the boat was energized and heated, and sodium fluoride was deposited on the electron transport layer at 0.02 nm / second to form a thin film having a thickness of 1 nm. Similarly, potassium fluoride was deposited on the sodium fluoride thin film at 0.02 nm / second to form an electron injection layer having a thickness of 1.5 nm.
  • An agent layer was provided, and a laminate of a polyethylene terephthalate (PET) film having a thickness of 12 ⁇ m was prepared.
  • PET polyethylene terephthalate
  • thermosetting adhesive as a sealing adhesive was uniformly applied at a thickness of 20 ⁇ m along the adhesive surface (shiny surface) of the aluminum foil of the sealing substrate using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Further, the sealing substrate is moved to a nitrogen atmosphere having a dew point temperature of ⁇ 80 ° C. or less and an oxygen concentration of 0.8 ppm, and is dried for 12 hours or more so that the moisture content of the sealing adhesive is 100 ppm or less. It was adjusted.
  • thermosetting adhesive an epoxy adhesive mixed with the following (A) to (C) was used.
  • the sealing substrate was closely attached to the laminate, and was tightly sealed using a pressure-bonding roll under pressure-bonding conditions of a pressure-rolling roll temperature of 100 ° C., a pressure of 0.5 MPa, and an apparatus speed of 0.3 m / min. .
  • the emission decay lifetimes ⁇ and ⁇ 0 , the absolute quantum yield PLQE ( ⁇ ), and the absolute quantum yield PLQE ( ⁇ 0 ) were measured.
  • the organic EL elements 3-2 to 3-16 satisfied the expressions (1) and (2) and also satisfied the expression (3) or (4).
  • the light emitting film for evaluation used for the measurement is the type of “host compound”, “phosphorescent light emitting compound” and “fluorescent light emitting compound” in Example 1, and the content (volume%) of each compound.
  • the phosphorescent compound single film is formed from the phosphorescent compound PD-1 and the host compound H-2 in the same manner except that the fluorescent compound is not included in the production of the evaluation light emitting film.
  • a single membrane was produced. In the production of a single film of the phosphorescent compound, the content of the phosphorescent compound was not changed, and the host compound was increased by the amount not containing the fluorescent compound.
  • Example 1 the presence or absence of overlap between the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound and the Stokes shift of the fluorescent compound were examined. As for 3-16, it is confirmed that the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound overlap each other, and the Stokes shift of the fluorescent compound is 0.1 eV or less. It was done.
  • the present invention can be used for an organic electroluminescence element and a method for producing an organic electroluminescence element.

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  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

L'objectif de la présente invention est de fournir un élément électroluminescent organique dans lequel une demi-vie de luminance appropriée peut être obtenue même lorsqu'il fonctionne à une luminance élevée (densité de courant élevée), et une efficacité lumineuse favorable est présentée. L'élément électroluminescent organique selon la présente invention est un élément électroluminescent organique ayant une couche électroluminescente, la couche électroluminescente contenant un composé lumineux phosphorescent et un composé lumineux fluorescent; le spectre d'émission du composé lumineux phosphorescent et le spectre d'absorption du composé lumineux fluorescent ont une région de chevauchement; la durée de vie de déclin de luminescence τ d'une couche unique de la couche électroluminescente et le rendement quantique absolu PLQE Φ d'une couche unique de la couche électroluminescente satisfont des conditions spécifiques; et le décalage de Stokes du composé lumineux fluorescent est inférieur ou égal à 0,1 eV.
PCT/JP2018/008977 2017-04-07 2018-03-08 Élément électroluminescent organique et procédé de fabrication d'élément électroluminescent organique WO2018186101A1 (fr)

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JP2002050483A (ja) * 2000-05-22 2002-02-15 Showa Denko Kk 有機エレクトロルミネッセンス素子および発光材料
JP2003077674A (ja) * 2000-10-04 2003-03-14 Mitsubishi Chemicals Corp 有機電界発光素子
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JP2005310766A (ja) * 2004-03-26 2005-11-04 Fuji Photo Film Co Ltd 有機電界発光素子
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