Organic light-emitting element

Abstract

Provided is an organic light-emitting element having an organic mixed layer containing a first organic compound, a second organic compound, and a third organic compound satisfying ES1 (A) > ES1 (B) > ES1 (C). ES1 (A) is the lowest excited singlet level of the first organic compound, ES1 (B) is the lowest excited singlet level of the second organic compound, and ES1 (C) is the lowest excited singlet level of the third organic compound. The second organic compound and the third organic compound are delayed fluorescent materials. The present invention can provide an organic light-emitting element having a long lifetime and high luminous efficiency.

Description

[0001] This application is a divisional application. The Chinese national application number of the application to which it is based is 201980076273.5, the international application number is PCT / JP2019 / 046675, the application date is November 28, 2019, the date of entry into China is May 19, 2021, and the name of the invention is “Organic Light-Emitting Element”. Technical Field

[0002] The present invention relates to an organic light emitting element using a delayed fluorescent material. Background Art

[0003] Research is actively being conducted to improve the luminous efficiency of organic light-emitting elements such as organic electroluminescent elements (organic EL elements). In particular, various studies have been conducted to improve the luminous efficiency by newly developing electron transport materials, hole transport materials, host materials, luminescent materials, etc. that constitute organic electroluminescent elements and combining them. Among them, research on organic light-emitting elements using delayed fluorescence materials is also seen.

[0004] Delayed fluorescence materials are compounds that emit fluorescence when returning to the ground state from the excited singlet state after reverse intersystem crossing from the excited triplet state to the excited singlet state in the excited state. Because the fluorescence generated by this pathway is observed later than the fluorescence from the excited singlet state directly generated from the ground state (normal fluorescence), it is called delayed fluorescence. Here, for example, when the luminescent compound is excited by the injection of a carrier, because the probability of the generation of the excited singlet state and the excited triplet state is statistically 25%:75%, if only the fluorescence from the directly generated excited singlet state is used, there is a limit to the improvement of the luminous efficiency. On the other hand, because the delayed fluorescent material can use the excited triplet state for fluorescence luminescence through the pathway via reverse intersystem crossing in addition to the excited singlet state, a high luminous efficiency can be obtained compared to the normal delayed fluorescent material.

[0005] As such delayed fluorescent materials, benzene derivatives having a heteroaryl group such as a carbazolyl group or a diphenylamino group and at least two cyano groups have been proposed, and it has been confirmed that high luminous efficiency is obtained by using the benzene derivatives in the light-emitting layer of an organic EL device (see Patent Document 1).

[0006] Furthermore, Non-Patent Document 1 reports that a carbazole dibenzonitrile derivative (4CzTPN) represented by the following formula is a thermally active delayed fluorescent material, and reports that an organic electroluminescent element using the carbazole dibenzonitrile derivative achieves high internal EL quantum efficiency.

[0007] [Chemical formula 1]

[0008]

[0009] On the other hand, it is also proposed that a delayed fluorescent material is used as an auxiliary dopant in a light-emitting layer instead of a light-emitting material (see Patent Document 2). Here, it is described that the light-emitting efficiency is improved by adding a delayed fluorescent material having a lowest excited singlet energy level between the main material and the fluorescent material to the light-emitting layer in addition to the main material and the fluorescent material.

[0010] Previous technical literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Publication No. 2014-43541

[0013] Patent Document 2: Japanese Patent Application Publication No. 2015-179809

[0014] Non-patent literature

[0015] Non-patent document 1: H. Uoyama, et al., Nature 492, 234 (2012) Summary of the invention

[0016] Technical issues to be solved by the invention

[0017] As mentioned above, in Patent Document 1, Patent Document 2 and Non-Patent Document 1, it is reported that high luminous efficiency is obtained in an organic electroluminescent element using a delayed fluorescent material. However, the present inventors have found that when an organic electroluminescent element is made according to the description of Patent Document 1 or Patent Document 2, it is difficult to ensure sufficient life. Specifically, because the luminescent quantum yield decreases when the concentration of the delayed fluorescent material in the light-emitting layer is increased to improve the life, it is difficult to take into account both the life and the luminous efficiency. In addition, because the driving voltage is also high, it is also necessary to reduce the driving voltage to achieve practical application. In particular, in an organic light-emitting element using a fluorescent material or a delayed fluorescent material as a red light-emitting body, research to solve these problems has not yet been fully carried out.

[0018] Under such circumstances, the present inventors have conducted intensive studies to achieve both long life and high luminous efficiency in an organic light-emitting element using a delayed fluorescent material.

[0019] Means for solving technical problems

[0020] As a result of in-depth research to achieve the above-mentioned purpose, the inventors have found that by adding multiple delayed fluorescent materials that meet specific conditions to the light-emitting layer, good lifespan and luminous efficiency can be achieved. In addition, it has been found that by forming a layer containing multiple delayed fluorescent materials as a layer adjacent to the light-emitting layer, good lifespan and luminous efficiency can also be achieved. The present invention is proposed based on this insight and specifically has the following structure.

[0021] [1] An organic light-emitting element having an organic mixed layer, the organic mixed layer comprising a first organic compound, a second organic compound and a third organic compound satisfying the following condition (a), wherein:

[0022] The second organic compound and the third organic compound are delayed fluorescent materials having structures different from each other.

[0023] Condition(a)E S1 (A)>E S1 (B)>E S1 (C)

[0024] (In the above formula, E S1 (A) represents the lowest excited singlet energy level of the first organic compound, E S1 (B) represents the lowest excited singlet energy level of the second organic compound, E S1 (C) represents the lowest excited singlet energy level of the third organic compound.)

[0025] [2] The organic light-emitting element according to [1], which is an organic electroluminescent element, comprising an anode, a cathode, and at least one organic layer including the organic mixed layer between the anode and the cathode.

[0026] [3] The organic light-emitting element according to [1] or [2], wherein the energy difference ΔE between the lowest excited singlet state of the second organic compound and the lowest excited triplet state at 77K is st It is less than 0.3 eV.

[0027] [4] The organic light-emitting element according to any one of [1] to [3], wherein the energy difference ΔE between the lowest excited singlet state of the third organic compound and the lowest excited triplet state at 77K is st It is less than 0.3 eV.

[0028] [5] The organic light-emitting element according to any one of [1] to [4], wherein the content of the second organic compound in the organic mixed layer is greater than the content of the third organic compound.

[0029] [6] The organic light-emitting element according to any one of [1] to [5], wherein the content of the second organic compound in the organic mixed layer is greater than the content of the first organic compound.

[0030] [7] The organic light-emitting element according to any one of [1] to [6], wherein the content of the second organic compound in the organic mixed layer is 45% by weight or more of the organic mixed layer.

[0031] [8] The organic light-emitting element according to any one of [1] to [7], wherein the content of the third organic compound in the organic mixed layer is 10% by weight or less of the organic mixed layer.

[0032] [9] The organic light-emitting element according to any one of [1] to [8], wherein the organic mixed layer does not contain a metal element.

[0033]

[10] An organic light-emitting element according to any one of [1] to [9], wherein the organic mixed layer is composed only of a compound composed of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms and sulfur atoms.

[0034]

[11] The organic light-emitting element according to any one of [1] to

[10] , wherein the second organic compound and the third organic compound both contain a dibenzonitrile structure.

[0035]

[12] An organic light-emitting element having an organic mixed layer, the organic mixed layer comprising a fifth organic compound, a sixth organic compound, a seventh organic compound and an eighth organic compound satisfying the following conditions (b) and (c),

[0036] The sixth organic compound and the seventh organic compound are delayed fluorescent materials having structures different from each other.

[0037] Condition (b)E S1 (D)>E S1 (E) or E S1 (D)>E S1 (F)

[0038] Condition (c)E S1 (E)>E S1 (F)>E S1 (G)

[0039] (In the above formula, E S1 (D) represents the lowest excited singlet energy level of the fifth organic compound, E S1 (E) represents the lowest excited singlet energy level of the sixth organic compound, and E S1 (F) represents the lowest excited singlet energy level of the seventh organic compound, E S1 (G) represents the lowest excited singlet energy level of the eighth organic compound.)

[0040]

[13] The organic light-emitting element according to

[12] , which is an organic electroluminescent element, comprising an anode, a cathode, and at least one organic layer including the organic mixed layer between the anode and the cathode.

[0041]

[14] The organic light-emitting element according to

[12] or

[13] , wherein the energy difference ΔE between the lowest excited singlet state of the sixth organic compound and the lowest excited triplet state at 77K is st It is less than 0.3 eV.

[0042]

[15] The organic light-emitting element according to any one of

[12] to

[14] , wherein the energy difference ΔE between the lowest excited singlet state of the seventh organic compound and the lowest excited triplet state at 77K is st It is less than 0.3 eV.

[0043]

[16] The organic light-emitting element according to any one of

[12] to

[15] , wherein the content of the sixth organic compound in the organic mixed layer is greater than the content of the seventh organic compound.

[0044]

[17] The organic light-emitting element according to any one of

[12] to

[16] , wherein the content of the sixth organic compound in the organic mixed layer is greater than the content of the fifth organic compound.

[0045]

[18] The organic light-emitting element according to any one of

[12] to

[17] , wherein the content of the fifth organic compound in the organic mixed layer is greater than the content of the seventh organic compound.

[0046]

[19] An organic light-emitting element according to any one of

[12] to

[18] , wherein the content of the fifth organic compound, the content of the sixth organic compound and the content of the seventh organic compound in the organic mixed layer are all greater than the content of the eighth organic compound.

[0047]

[20] The organic light-emitting element according to any one of

[12] to

[19] , wherein the content of the sixth organic compound in the organic mixed layer is 45% by weight or more of the organic mixed layer.

[0048]

[21] The organic light-emitting element according to any one of

[12] to

[20] , wherein the content of the seventh organic compound in the organic mixed layer is less than 25% by weight of the organic mixed layer.

[0049]

[22] The organic light-emitting element according to any one of

[12] to

[21] , wherein the organic mixed layer does not contain a metal element.

[0050]

[23] An organic light-emitting element according to any one of

[12] to

[22] , wherein the organic mixed layer is composed only of a compound composed of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms and sulfur atoms.

[0051]

[24] The organic light-emitting element according to any one of

[12] to

[23] , wherein the sixth organic compound and the seventh organic compound both contain a dibenzonitrile structure.

[0052]

[25] The organic light-emitting element according to any one of [1] to

[24] , wherein the organic mixed layer is a light-emitting layer.

[0053]

[26] The organic light-emitting element according to any one of [1] to

[24] , wherein the organic mixed layer is formed as a layer different from the light-emitting layer.

[0054] Effects of the Invention

[0055] According to the present invention, an organic light emitting element having high light emission efficiency and long life can be provided, and an organic light emitting element having a suppressed driving voltage can also be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic cross-sectional view showing an example of a layer structure of an organic electroluminescent element. DETAILED DESCRIPTION

[0057] The content of the present invention is described in detail below. The description of the constituent elements described below is sometimes based on representative embodiments or specific examples of the present invention, but the present invention is not limited to such embodiments or specific examples. In addition, in this article, the numerical range represented by "to" means a range that includes the numerical values ​​described before and after "to" as the lower limit and upper limit. In addition, the isotope types of hydrogen atoms present in the molecules of the compounds used in the present invention are not particularly limited. For example, all hydrogen atoms in the molecules can be 1 H, or part or all of it 2 H (deuterium D).

[0058] <Organic Light Emitting Element, Aspect 1>

[0059] The organic light emitting device according to the first aspect of the present invention is an organic light emitting device having an organic mixed layer including a first organic compound, a second organic compound and a third organic compound. The first organic compound, the second organic compound and the third organic compound satisfy the following condition (a).

[0060] Condition(a)E S1 (A)>ES1 (B)>E S1 (C)

[0061] In condition (a), E S1 (A) represents the lowest excited singlet energy level of the first organic compound, E S1 (B) represents the lowest excited singlet energy level of the second organic compound, E S1 (C) represents the lowest excited singlet energy level of the third organic compound. In the following description, the organic light-emitting device according to the first aspect may be referred to as a "first organic light-emitting device".

[0062] The second organic compound is a delayed fluorescence material. And, the third organic compound is a delayed fluorescence material having a different structure from the second organic compound. The "delayed fluorescence material" in the present invention is an organic compound that generates reverse intersystem crossing from an excited triplet state to an excited singlet state in an excited state, and emits fluorescence (delayed fluorescence) when returning from the excited singlet state to the ground state. In the present invention, when the luminescence lifetime is measured by a fluorescence lifetime measurement system (such as a streak camera system manufactured by Hamamatsu Photonics KK), a material in which fluorescence having a luminescence lifetime of more than 100 ns (nanoseconds) is observed is called a delayed fluorescence material.

[0063] The difference ΔE between the lowest excited singlet energy level of the second organic compound and the lowest excited triplet energy level at 77K ST It is preferably 0.3 eV or less, more preferably 0.25 eV or less, more preferably 0.2 eV or less, more preferably 0.15 eV or less, further preferably 0.1 eV or less, further preferably 0.07 eV or less, further preferably 0.05 eV or less, further preferably 0.03 eV or less, and particularly preferably 0.01 eV or less.

[0064] The difference between the lowest excited singlet energy level of the third organic compound and the lowest excited triplet energy level at 77K, ΔE ST It is preferably 0.3 eV or less, more preferably 0.25 eV or less, more preferably 0.2 eV or less, more preferably 0.15 eV or less, further preferably 0.1 eV or less, further preferably 0.07 eV or less, further preferably 0.05 eV or less, further preferably 0.03 eV or less, and particularly preferably 0.01 eV or less.

[0065] If ΔE STThe thermally activated delayed fluorescent material absorbs the heat emitted by the device and relatively easily reverses the intersystem crossing from the excited triplet state to the excited singlet state, thereby enabling the excited triplet state to contribute to luminescence with good energy efficiency.

[0066] [The lowest excited singlet energy level (E S1 ) and the lowest excited triplet energy level (E T1 ) ST Measurement of]

[0067] The lowest excited singlet energy level (E S1 ) and the lowest excited triplet energy level (E T1 ) ST The lowest excited singlet energy level (E S1 ) and the lowest excited triplet energy level (E T1 ), and by calculating ΔE ST =E S1 -E T1 To find the value.

[0068] (1) The lowest excited singlet energy level (E S1 )

[0069] Prepare a thin film or toluene solution (concentration 10 -5 mol / L) as a sample. Measure the fluorescence spectrum of the sample at room temperature (300K). In the fluorescence spectrum, the vertical axis is set to luminescence and the horizontal axis is set to wavelength. Draw a tangent to the rise of the short-wave side of the luminescence spectrum, and find the wavelength value λedge[nm] of the intersection of the tangent and the horizontal axis. The wavelength value is converted into an energy value using the conversion formula shown below as E S1 .

[0070] Conversion formula: E S1 [eV] = 1239.85 / λedge

[0071] The measurement of the emission spectrum in the examples described below was performed using an LED light source (M300L4 manufactured by Thorlabs Japan Inc.) as an excitation light source and a detector (PMA-12 multi-channel spectrometer C10027-01 manufactured by Hamamatsu Photonics KK).

[0072] (2) The lowest excited triplet energy level (E T1 )

[0073] will be related to the lowest excited singlet energy level (E S1 ) is cooled to 77[K] by liquid nitrogen, and the sample for phosphorescence measurement is irradiated with excitation light (300nm), and the phosphorescence is measured using a detector. The luminescence from 100 milliseconds after irradiation with the excitation light is made into a phosphorescence spectrum. A tangent is drawn relative to the rise of the short-wavelength side of the phosphorescence spectrum, and the wavelength value λedge[nm] of the intersection of the tangent and the horizontal axis is calculated. The wavelength value is converted into an energy value using the conversion formula shown below as E T1 .

[0074] Conversion formula: E T1 [eV] = 1239.85 / λedge

[0075] The rising tangent line for the short wavelength side of the phosphorescence spectrum is drawn as follows. Consider the tangent line at each point on the curve toward the long wavelength side when moving from the short wavelength side of the phosphorescence spectrum to the maximum value on the shortest wavelength side among the maximum values ​​of the spectrum on the spectrum curve. As the curve rises (i.e., as the vertical axis increases), the slope of the tangent line increases. The tangent line drawn at the point where the value of the slope takes the maximum value is set as the rising tangent line for the short wavelength side of the phosphorescence spectrum.

[0076] In addition, the maximum point with a peak intensity of less than 10% of the maximum peak intensity of the spectrum does not include the maximum value on the above-mentioned shortest wavelength side, and the tangent drawn at the point closest to the maximum value on the shortest wavelength side and where the slope value takes the maximum value is set as the rising tangent to the short wavelength side of the phosphorescence spectrum.

[0077] (First organic compound)

[0078] The first organic compound is an organic compound having a lower excited singlet energy than the second organic compound and the third organic compound, and the first organic compound has a function as a host material responsible for transporting a carrier or a function of confining the energy of the third organic compound in the compound. Thus, the third organic compound can efficiently convert the energy generated by the recombination of holes and electrons within the molecule and the energy received from the first organic compound and the second organic compound into light emission, thereby realizing an organic light-emitting element with high light emission efficiency.

[0079] Furthermore, the first organic compound is preferably an organic compound having hole transport capability, electron transport capability, preventing the emission of light at a long wavelength, and having a high glass transition temperature. Furthermore, in a preferred aspect of the present invention, the first organic compound is selected from compounds that do not emit delayed fluorescence. The following includes preferred compounds that can be used as the first organic compound.

[0080] [Chemical formula 2]

[0081]

[0082] [Chemical formula 3]

[0083]

[0084] [Chemical formula 4]

[0085]

[0086] [Chemical formula 5]

[0087]

[0088] [Chemical formula 6]

[0089]

[0090] [Chemical formula 7]

[0091]

[0092] [Chemical formula 8]

[0093]

[0094] [Chemical formula 9]

[0095]

[0096] (Second organic compound and third organic compound)

[0097] The second organic compound is a delayed fluorescence material whose lowest excited singlet energy is less than that of the first organic compound and whose lowest excited singlet energy is greater than that of the third organic compound. The second organic compound only needs to be a compound that can emit delayed fluorescence under certain conditions. In the first organic light-emitting element of the present invention, it is not necessary to emit delayed fluorescence from the second organic compound. In the first organic light-emitting element of the present invention, the second organic compound receives energy from the first organic compound in an excited singlet state and transitions to an excited singlet state. Furthermore, the second organic compound may receive energy from the first organic compound in an excited triplet state and transition to an excited triplet state. Because ΔE of the second organic compound ST Since the second organic compound in the triplet excited state is small, reverse intersystem crossing to the second organic compound in the singlet excited state is easy. The second organic compound in the singlet excited state generated by these pathways gives energy to the third organic compound, causing the third organic compound to transition to the singlet excited state.

[0098] The third organic compound is a delayed fluorescence material whose lowest excited singlet energy is smaller than that of the first organic compound and the second organic compound. The third organic compound only needs to be a compound capable of emitting delayed fluorescence under certain conditions, and the delayed fluorescence from the third organic compound is emitted in the first organic light-emitting element of the present invention. The light emitted from the third organic compound usually includes delayed fluorescence. The largest component of the light emitted from the first organic light-emitting element of the present invention is the light emitted from the third organic compound. The third organic compound receives energy from the first organic compound and the second organic compound in the excited singlet state and from the second organic compound in the excited singlet state through reverse intersystem crossing from the excited triplet state, and transitions to the excited singlet state. Furthermore, because the ΔE of the third organic compound is ST Small, so the third organic compound in the triplet excited state easily reverses intersystem crossing to the third organic compound in the singlet excited state. The excited singlet state generated by these pathways emits fluorescence when it returns to the ground state later. As a delayed fluorescence material used as the third organic compound, as long as it can receive energy from the first organic compound and the second organic compound and emit light, it is not subject to any particular restrictions. In a preferred aspect of the present invention, each compound is selected and combined so that there is an overlap between the emission wavelength region of the second organic compound and the absorption wavelength region of the third organic compound. In particular, it is preferred to overlap the edge of the long wavelength side of the emission spectrum of the second organic compound with the edge of the short wavelength side of the absorption spectrum of the third organic compound.

[0099] As the second organic compound and the third organic compound, a known delayed fluorescent material may be used, or an unknown delayed fluorescent material may be used.

[0100] Preferred delayed fluorescent materials may include paragraphs 0008 to 0048 and 0095 to 0133 of WO2013 / 154064, paragraphs 0007 to 0047 and 0073 to 0085 of WO2013 / 011954, paragraphs 0007 to 0033 and 0059 to 0066 of WO2013 / 011955, paragraphs 0008 to ... of WO2013 / 081088, paragraphs 0008 to 0096 of WO2013 / 154064, paragraphs 0007 to 0047 and 0073 to 0085 of WO2013 / 011954, paragraphs 0007 to 0033 and 0059 to 0066 of WO2013 071 and 0118 to 0133, 0009 to 0046 and 0093 to 0134 of Japanese Patent Application Publication No. 2013-256490, 0008 to 0020 and 0038 to 0040 of Japanese Patent Application Publication No. 2013-116975, 0007 to 0032 and 0079 to 0084 of WO2013 / 133359, 0 008 to 0054 and 0101 to 0121, 0007 to 0041 and 0060 to 0069 of Japanese Patent Application Publication No. 2014-9352, 0008 to 0048 and 0067 to 0076 of Japanese Patent Application Publication No. 2014-9224, 0013 to 0025 of Japanese Patent Application Publication No. 2017-119663, 0013 to 0025 of Japanese Patent Application Publication No. 2017-119664 The compounds included in the general formula described in paragraph 26, paragraphs 0012 to 0025 of Japanese Patent Application Publication No. 2017-222623, paragraphs 0010 to 0050 of Japanese Patent Application Publication No. 2017-226838, paragraphs 0012 to 0043 of Japanese Patent Application Publication No. 2018-100411, and paragraphs 0016 to 0044 of WO2018 / 047853, and materials that are exemplified compounds and emit delayed fluorescence.Furthermore, Japanese Patent Application Publication No. 2013-253121, WO2013 / 133359, WO2014 / 034535, WO2014 / 115743, WO2014 / 122895, WO2014 / 126200, WO2014 / 136758, WO2014 / 133121 WO2014 / 136860, WO2014 / 196585, WO2014 / 189122, WO2014 / 168101, WO2015 / 008580, WO2014 / 203840, WO2015 / 002213, WO2015 / 016200, WO20 15 / 019725, WO2015 / 072470, WO2015 / 108049, WO2015 / 080182, WO2015 / 072537, WO2015 / 080183, Japanese Patent Application No. 2015-129240, WO2015 / 129714, WO2015 / 129 715, WO2015 / 133501, WO2015 / 136880, WO2015 / 137244, WO2015 / 137202, WO2015 / 137136, WO2015 / 146541, WO2015 / 159541. In addition, the above-mentioned publications described in this paragraph are incorporated herein as part of this document.

[0101] As the delayed fluorescent material of the present invention, a compound represented by the following general formula (1) and emitting delayed fluorescence can be preferably used. In a preferred embodiment of the present invention, the second organic compound and the third organic compound can both be compounds represented by the general formula (1).

[0102] [Chemical formula 10]

[0103] General formula (1)

[0104]

[0105] In the general formula (1), X 1 ~X 5 represents N or CR. R represents a hydrogen atom or a substituent. 1 ~X 5 When two or more of X represent CR, these CRs may be the same as or different from each other. 1 ~X 5At least one of them is CD (D in this case represents a donor group). 1 ~X 5 When all of are CR, Z represents an acceptor group. 1 ~X 5 When at least one of is N, Z represents a hydrogen atom or a substituent.

[0106] Particularly preferred compounds among the compounds represented by the general formula (1) are compounds represented by the following general formula (2).

[0107] [Chemical formula 11]

[0108] General formula (2)

[0109]

[0110] In the general formula (2), X 1 ~X 5 represents N or CR. R represents a hydrogen atom or a substituent. 1 ~X 5 When two or more of X represent CR, these CRs may be the same as or different from each other. 1 ~X 5 At least one of them is CD (D herein represents a donor group).

[0111] For the description and preferred range of the substituent represented by Z of the general formula (1), reference can be made to the description and preferred range of the substituent of the general formula (7) described later. The acceptor group represented by Z of the general formula (1) is a group having the property of donating electrons to the ring bonded to Z, and can be selected from, for example, a group having a positive Hammett's σp value. The donor group represented by D of the general formula (1) and the general formula (2) is a group having the property of attracting electrons to the ring bonded to D, and can be selected from, for example, a group having a negative Hammett's σp value. In the following, the acceptor group is sometimes referred to as A.

[0112] Here, "Hamiett's σp value" is proposed by LP Hammett, and is a value that quantifies the effect of a substituent on the reaction rate or equilibrium of a para-substituted benzene derivative. Specifically, it is the following equation that holds true between the substituent in the para-substituted benzene derivative and the reaction rate constant or equilibrium constant:

[0113] log(k / k 0 )=ρσp

[0114] or

[0115] log(k / k 0 )=ρσp

[0116] In the above formula, k represents the rate constant of the benzene derivative without substituents, k 0 represents the rate constant of the benzene derivative substituted with a substituent, K represents the equilibrium constant of the benzene derivative without a substituent, k 0 represents the equilibrium constant of the benzene derivative substituted by the substituent, and ρ represents the reaction constant determined by the type and conditions of the reaction. For the description of the "Hamiett's σp value" in the present invention and the numerical value of each substituent, reference can be made to the description of the σp value in Hansch, C. et.al., Chem. Rev., 91, 165-195 (1991).

[0117] In the general formula (1) and the general formula (2), X 1 ~X 5 Indicates N or CR, but at least one is CD. X 1 ~X 5 The number of N is 0 to 4, for example, X 1 and X 3 and X 5 , X 1 and X 3 , X 1 and X 4 , X 2 and X 3 , X 1 and X 5 , X 2 and X 4 , X only 1 , X only 2 , X only 3 For N. X 1 ~X 5 The number of CDs in is 1 to 5, preferably 2 to 5. For example, X 1 and X 2 and X 3 and X 4 and X 5 , X 1 and X 2 and X 4 and X 5 , X 1 and X 2 and X 3 and X 4 , X 1 and X 3 and X 4 and X 5 , X 1 and X 3 and X 5 , X 1 and X 2and X 5 , X 1 and X 2 and X 4 , X 1 and X 3 and X 4 , X 1 and X 3 , X 1 and X 4 , X 2 and X 3 , X 1 and X 5 , X 2 and X 4 , X only 1 , X only 2 , X only 3 For CD. X 1 ~X 5 At least one of the above may be CA. A herein represents an acceptor group. 1 ~X 5 The number of CA in is preferably 0 to 2, more preferably 0 or 1. A as CA may preferably include a cyano group. 1 ~X 5 They can be CD or CA respectively and independently.

[0118] When X 1 ~X 5 When two adjacent Rs in represent CR, two Rs can bond to each other to form a cyclic structure. The cyclic structure formed by bonding to each other can be an aromatic ring or an aliphatic ring, or a structure containing heteroatoms, and the cyclic structure can be a condensed ring of more than 2 rings. The heteroatoms described herein are preferably atoms selected from the group consisting of nitrogen atoms, oxygen atoms and sulfur atoms. The example of the cyclic structure formed can include a benzene ring, a naphthalene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, an imidazoline ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a cyclohexadiene ring, a cyclohexene ring, a cyclopentene ring, a cycloheptatriene ring, a cycloheptadiene ring, a cycloheptene ring, a furan ring, a thiophene ring, a naphthyridine ring, a quinoxaline ring, a quinoline ring, etc. For example, a ring formed by the condensation of multiple rings can be formed, such as triphenylene.

[0119] The donor group D in the general formula (1) and the general formula (2) is preferably a group represented by the following general formula (3), for example.

[0120] [Chemical formula 12]

[0121] General formula (3)

[0122]

[0123] In the general formula (3), R 11 and R 12 R each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. 11 and R 12 They can bond to each other to form a cyclic structure. L represents a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group. The substituent of the arylene group or heteroarylene group that can be introduced into L can be a group represented by the general formula (1) or the general formula (2), or a group represented by the general formulas (3) to (6) described later. These groups represented by (1) to (6) can be introduced into L until the maximum number of substituents that can be introduced is reached. Furthermore, if multiple groups represented by the general formulas (1) to (6) are introduced, these substituents can be the same as or different from each other. * represents the bonding position to the carbon atom (C) of the ring skeleton constituting the ring in the general formula (1) or the general formula (2).

[0124] The "alkyl" described herein can be any one of a straight chain, a branched chain, or a cyclic chain. Furthermore, two or more of the straight chain part, the cyclic part, and the branched chain part can be mixed. The number of carbon atoms of the alkyl group can be set to, for example, more than 1, more than 2, or more than 4. Furthermore, the number of carbon atoms can be set to less than 30, less than 20, less than 10, less than 6, or less than 4. Specific examples of alkyl groups can include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, 2-ethylhexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, isononyl, n-decyl, isododecyl, cyclopentyl, cyclohexyl, and cycloheptyl. The alkyl group as a substituent can be further substituted by an aryl group.

[0125] "Alkenyl" can be any one of straight chain, branched chain, and cyclic. Furthermore, two or more of the straight chain part, cyclic part, and branched chain part can be mixed. The number of carbon atoms of the alkenyl group can be set to, for example, more than 2 or more than 4. Furthermore, the number of carbon atoms can be set to less than 30, less than 20, less than 10, less than 6, or less than 4. Specific examples of alkenyl groups can include vinyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, n-pentenyl, isopentenyl, n-hexenyl, isohexenyl, and 2-ethylhexenyl. The alkenyl group as a substituent can be further substituted by a substituent.

[0126] "Aryl" and "heteroaryl" may be a single ring or a condensed ring formed by condensing two or more rings. When it is a condensed ring, the number of condensed rings is preferably 2 to 6, for example, it can be selected from 2 to 4. Specific examples of the ring may include a benzene ring, a pyridine ring, a pyrimidine ring, a triazine ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a triphenylene ring, a quinoline ring, a pyrazine ring, a quinoxaline ring, and a naphthyridine ring. Specific examples of arylene or heteroarylene may include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 2-pyridyl, 3-pyridyl, and 4-pyridyl.

[0127] The substituent refers to a monovalent group that can be substituted with a hydrogen atom, and does not include a condensed group. For the description and preferred range of the substituent, reference can be made to the description and preferred range of the substituent in the general formula (7) described below.

[0128] The compound represented by the general formula (3) is preferably a compound represented by any one of the following general formulas (4) to (6).

[0129] [Chemical formula 13]

[0130] General formula (4)

[0131]

[0132] General formula (5)

[0133]

[0134] General formula (6)

[0135]

[0136] In the general formulas (4) to (6), R 51 ~R 60 , R 61 ~R 68 , R 71 ~R 78 Each independently represents a hydrogen atom or a substituent. For the description and preferred range of the substituents described here, reference can be made to the description and preferred range of the substituents in the general formula (7) described later. 51 ~R 60 , R 61 ~R 68 , R 71 ~R 78It is also preferred that each is independently a group represented by any one of the above-mentioned general formulae (4) to (6). The number of substituents in the general formulae (4) to (6) is not particularly limited. It is also preferred that all are unsubstituted (i.e., hydrogen atoms). Furthermore, when there are two or more substituents in each of the general formulae (4) to (6), these substituents may be the same or different. When there are substituents in the general formulae (4) to (6), if in the general formula (4), the substituent is preferably R 52 ~R 59 If any of the substituents is in the general formula (5), then the substituent is preferably R 62 ~R 67 If any of the substituents is in the general formula (6), then the substituent is preferably R 72 ~R 77 Any one of .

[0137] In the general formulas (4) to (6), R 51 and R 52 , R 52 and R 53 , R 53 and R 54 , R 54 and R 55 , R 55 and R 56 , R 56 and R 57 , R 57 and R 58 , R 58 and R 59 , R 59 and R 60 , R 61 and R 62 , R 62 and R 63 , R 63 and R 64 , R 65 and R 66 , R 66 and R 67 , R 67 and R 68 , R 71 and R 72 , R 72 and R 73 , R 73 and R 74 , R 75 and R 76 , R 76 and R 77 , R 77 and R 78For the description and preferred examples of the ring structure, reference can be made to X in the above general formula (1) and general formula (2). 1 ~X 5 Description and preferred examples of the ring structure in.

[0138] In the general formula (6), X represents a divalent oxygen atom, a sulfur atom, a substituted or unsubstituted nitrogen atom, a substituted or unsubstituted carbon atom, a substituted or unsubstituted silicon atom and a carbonyl group with a bonding chain length of 1 atom, or a divalent substituted or unsubstituted vinyl group, a substituted or unsubstituted vinylene group, a substituted or unsubstituted o-arylene group or a substituted or unsubstituted o-heteroarylene group with a bonding chain length of 2 atoms. For specific examples and preferred ranges of the substituents, reference can be made to the description of the substituents in the general formulas (1) and (2).

[0139] In general formulas (4) to (6), L 12 ~L 14 represents a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group. 12 ~L 14 For the description and preferred range of the arylene group or heteroarylene group represented by L, reference can be made to the description and preferred range of the arylene group or heteroarylene group represented by L. 12 ~L 14 Preferably, it is a single bond, a substituted or unsubstituted arylene group. The substituents of the arylene group and the heteroarylene group described herein may be groups represented by the general formulae (1) to (6). The groups represented by the general formulae (1) to (6) may be introduced into L 11 ~L 14 , until the maximum number of substituents that can be introduced is reached. Furthermore, if multiple groups represented by general formulae (1) to (6) are introduced, these substituents may be the same as or different from each other. * represents the bonding position to the carbon atom (C) of the ring skeleton constituting the ring in general formula (1) or general formula (2).

[0140] In the present invention, it is particularly preferred to use a compound represented by the following general formula (7) and emitting delayed fluorescence as a delayed fluorescence material. In a preferred embodiment of the present invention, the second organic compound and the third organic compound can both be compounds represented by the general formula (7). It is preferred that the second organic compound and the third organic compound are both compounds containing a dibenzonitrile structure.

[0141] [Chemical formula 14]

[0142] General formula (7)

[0143]

[0144] In the general formula (7), R 1 ~R 5 0 to 4 of them represent cyano groups, R 1 ~R 5 At least one of them represents a substituted amino group, and the remaining R 1 ~R 5 represents a hydrogen atom or a substituent other than a cyano group and a substituted amino group.

[0145] The substituted amino group described herein is preferably a substituted or unsubstituted diarylamino group, and the two aryl groups constituting the substituted or unsubstituted diarylamino group may be connected to each other. The connection may be made by a single bond (in this case, a carbazole ring is formed), or by a substituted or unsubstituted diarylamino group such as -O-, -S-, -N(R 6 )-、-C(R 7 )(R 8 )-、-Si(R 9 )(R 10 )- and the like. Here, R 6 ~R 10 represents a hydrogen atom or a substituent, R 7 and R 8 , R 9 and R 10 They can be connected to each other to form a ring structure.

[0146] The substituted amino group may be R 1 ~R 5 Any one of them, for example, can be R 1 and R 2 , R 1 and R 3 , R 1 and R 4 , R 1 and R 5 , R 2 and R 3 , R 2 and R 4 , R 1 and R 2 and R 3 , R 1 and R 2 and R 4 , R 1 and R 2 and R 5 , R 1 and R 3 and R 4 , R 1 and R 3 and R 5 , R 2 and R 3 and R4 , R 1 and R 2 and R 3 and R 4 , R 1 and R 2 and R 3 and R 5 , R 1 and R 2 and R 4 and R 5 , R 1 and R 2 and R 3 and R 4 and R 5 Used as substituted amino, etc. Cyano can also be R 1 ~R 5 Any one of them, for example, can be R 1 , R 2 , R 3 , R 1 and R 2 , R 1 and R 3 , R 1 and R 4 , R 1 and R 5 , R 2 and R 3 , R 2 and R 4 , R 1 and R 2 and R 3 , R 1 and R 2 and R 4 , R 1 and R 2 and R 5 , R 1 and R 3 and R 4 , R 1 and R 3 and R 5 , R 2 and R 3 and R 4 Used as cyano group, etc.

[0147] R is neither cyano nor substituted amino 1 ~R 5represents a hydrogen atom or a substituent. Examples of the substituent described herein may include a hydroxyl group, a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an alkyl group (e.g., having 1 to 40 carbon atoms), an alkoxy group (e.g., having 1 to 40 carbon atoms), an alkylthio group (e.g., having 1 to 40 carbon atoms), an aryl group (e.g., having 6 to 30 carbon atoms), an aryloxy group (e.g., having 6 to 30 carbon atoms), an arylthio group (e.g., having 6 to 30 carbon atoms), a heteroaryl group (e.g., having 5 to 30 atoms in the ring skeleton), a heteroaryloxy group (e.g., having 5 to 30 atoms in the ring skeleton), a heteroarylthio group The substituent group A comprises a group (e.g., a ring skeleton having 5 to 30 atoms), an acyl group (e.g., a carbon number of 1 to 40), an alkenyl group (e.g., a carbon number of 1 to 40), an alkynyl group (e.g., a carbon number of 1 to 40), an alkoxycarbonyl group (e.g., a carbon number of 1 to 40), an aryloxycarbonyl group (e.g., a carbon number of 1 to 40), a heteroaryloxycarbonyl group (e.g., a carbon number of 1 to 40), a silyl group (e.g., a trialkylsilyl group having 1 to 40 carbon atoms), a nitro group, and the groups listed above further substituted by one or more of the groups listed above. Preferred examples of the substituent when the aryl group of the diarylamino group is substituted may include the substituents of the substituent group A, and may also include a cyano group and a substituted amino group.

[0148] For specific examples of the compound group and compounds included in the general formula (7), reference can be made to paragraphs 0008 to 0048 of WO2013 / 154064, paragraphs 0009 to 0030 of WO2015 / 080183, paragraphs 0006 to 0019 of WO2015 / 129715, paragraphs 0013 to 0025 of Japanese Patent Application No. 2017-119663, and paragraphs 0013 to 0026 of Japanese Patent Application No. 2017-119664, which are incorporated herein as a part of this document. Among them, the following compounds can be included as specific examples of preferred compounds. In the following structural formula, Me represents a methyl group, t-Bu represents a tert-butyl group, and Ph represents a phenyl group. Unless otherwise stated, R represents a hydrogen atom or a substituent, and the substituent is a methyl group, a tert-butyl group, a phenyl group, or a carbazole group.

[0149] [Chemical formula 15]

[0150]

[0151] [Chemical formula 16]

[0152]

[0153] [Chemical formula 17]

[0154]

[0155] [Chemical formula 18]

[0156]

[0157] [Chemical formula 19]

[0158]

[0159] [Chemical formula 20]

[0160]

[0161] [Chemical formula 21]

[0162]

[0163] Furthermore, the following compounds are also preferred as the compound.

[0164] [Chemical formula 22]

[0165]

[0166] In addition, a compound represented by the following general formula (8) and emitting delayed fluorescence can be particularly preferably used as the delayed fluorescence material of the present invention. In a preferred embodiment of the present invention, the second organic compound and the third organic compound can both be compounds represented by general formula (8).

[0167] [Chemical formula 23]

[0168] General formula (8)

[0169]

[0170] In the general formula (8), Y 1 , Y 2 and Y 3 Any two of them represent nitrogen atoms and the remaining one represents a methine or Y 1 , Y 2 and Y 3 All of Z represent nitrogen atoms. 1 and Z 2 R each independently represents a hydrogen atom or a substituent. 11 ~R 18 Each independently represents a hydrogen atom or a substituent, R 11 ~R 18 At least one of them is preferably a substituted or unsubstituted arylamino group or a substituted or unsubstituted carbazole group. The benzene ring constituting the arylamino group and the benzene ring constituting the carbazole group may be respectively connected to R 11 ~R 18Together they form a single bond or a linking group. Also, the compound represented by the general formula (8) contains at least two carbazole structures in the molecule. 1 , Z 2 Examples of the substituents that can be employed may include the substituents of the above-mentioned substituent group A. Also, regarding R 11 ~R 18 Specific examples of substituents that can be used for the above-mentioned arylamino group and carbazole group include substituents of the above-mentioned substituent group A, cyano group, substituted arylamino group, and substituted alkylamino group. In addition, R 11 and R 12 , R 12 and R 13 , R 13 and R 14 , R 15 and R 16 , R 16 and R 17 , R 17 and R 18 They may be bonded to each other to form a ring structure.

[0171] Among the compounds represented by the general formula (8), the compounds represented by the general formula (9) are particularly useful.

[0172] [Chemical formula 24]

[0173] General formula (9)

[0174]

[0175] In the general formula (9), Y 1 , Y 2 and Y 3 Any two of them represent nitrogen atoms and the remaining one represents a methine or Y 1 , Y 2 and Y 3 All of Z represent nitrogen atoms. 2 represents a hydrogen atom or a substituent. 11 ~R 18 and R 21 ~R 28 R each independently represents a hydrogen atom or a substituent. 11 ~R 18 At least one and / or R 21 ~R 28 At least one of them preferably represents a substituted or unsubstituted arylamino group or a substituted or unsubstituted carbazolyl group. The benzene ring constituting the arylamino group and the benzene ring constituting the carbazolyl group may be respectively connected to R 11 ~R 18 or R 21 ~R 28Together they form a single bond or a linking group. Z 2 Examples of the substituents that can be employed may include the substituents of the above-mentioned substituent group A. Also, regarding R 11 ~R 18 , R 21 ~R 28 Specific examples of substituents that can be used for the above-mentioned arylamino group and carbazole group include substituents of the above-mentioned substituent group A, cyano group, substituted arylamino group, and substituted alkylamino group. In addition, R 11 and R 12 , R 12 and R 13 , R 13 and R 14 , R 15 and R 16 , R 16 and R 17 , R 17 and R 18 , R 21 and R 22 , R 22 and R 23 , R 23 and R 24 , R 25 and R 26 , R 26 and R 27 , R 27 and R 28 They may be bonded to each other to form a ring structure.

[0176] For specific examples of the compound group and compounds included in general formula (9), reference can be made to the compounds described in paragraphs 0020 to 0062 of WO2013 / 081088 or Appl. Phys. Let, 98, 083302 (2011), which are incorporated herein by reference. Among them, the following compounds can be particularly included as specific examples of preferred compounds.

[0177] [Chemical formula 25]

[0178]

[0179] The following compounds can also be used as the delayed fluorescent material.

[0180] [Chemical formula 26]

[0181]

[0182] [Chemical formula 27]

[0183]

[0184] [Chemical formula 28]

[0185]

[0186] [Chemical formula 29]

[0187]

[0188] The maximum emission wavelength of the compound that can be used as the third organic compound of the present invention is not particularly limited. Therefore, a delayed fluorescent material having a maximum emission wavelength in the visible region (380 to 780 nm) or a delayed fluorescent material having a maximum emission wavelength in the infrared region (780 nm to 1 mm) can be appropriately selected and used. For example, a delayed fluorescent material having a maximum emission wavelength in the range of 500 to 780 nm in the region of 380 to 780 nm can be selected and used. For example, a delayed fluorescent material having a maximum emission wavelength in the green range of 500 to 570 nm or a delayed fluorescent material having a maximum emission wavelength in the red range of 650 to 780 nm can be selected. Specific examples of delayed fluorescent materials having a maximum emission wavelength in the range of 500 to 780 nm may include the following compounds. In addition, the organic mixed layer of the present invention may be configured to not contain a light-emitting material having a maximum emission wavelength at 400 to 490 nm.

[0189] [Chemical formula 30]

[0190]

[0191] A delayed fluorescent material used as the second organic compound of the present invention and a delayed fluorescent material used as the third organic compound are selected and combined to satisfy condition (a). A preferred aspect of the present invention may include an aspect in which the second organic compound and the third organic compound are selected and combined from delayed fluorescent materials having the same basic skeleton. For example, the second organic compound and the third organic compound can be selected and used from the delayed fluorescent materials represented by the above-mentioned general formula (1). Furthermore, the second organic compound and the third organic compound can be selected and used from the delayed fluorescent materials represented by the above-mentioned general formula (2).

[0192] (4th organic compound)

[0193] The first organic light-emitting element may further include organic compounds other than the first to third organic compounds in the organic mixed layer. The organic compound that may be included in the organic mixed layer may include a light-emitting material (hereinafter referred to as the "fourth organic compound") whose lowest excited singlet energy is lower than that of the first, second and third organic compounds. This fourth organic compound can receive energy from the first, second and third organic compounds in the excited singlet state and the second and third organic compounds that undergo reverse intersystem crossing from the excited triplet state to become the excited singlet state, and then emit light when returning to the ground state. As a light emitter used as the fourth organic compound, as long as it can receive energy from the first to third organic compounds and emit light, it is not particularly limited, and the light emission may be fluorescence, delayed fluorescence or phosphorescence. Among them, the light-emitting material used as the fourth organic compound is preferably a light-emitting material that emits fluorescence when returning from the lowest excited singlet energy level to the ground state energy level. Two or more fourth organic compounds may be used as long as they are luminescent materials with a minimum excited singlet energy lower than that of the first organic compound, the second organic compound, and the third organic compound. For example, a desired color can be emitted by using two or more fourth organic compounds with different luminescent colors at the same time.

[0194] The fourth organic compound may include anthracene derivatives, naphthacene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, Derivatives, rubrene derivatives, coumarin derivatives, pyran derivatives, stilbene derivatives, fluorene derivatives, anthracene derivatives, pyrromethene derivatives, terphenyl derivatives, terphenylene derivatives, fluoranthene derivatives, amine derivatives, quinacridone derivatives, oxadiazole derivatives, malononitrile derivatives, pyran derivatives, carbazole derivatives, julolidine derivatives, thiazole derivatives, derivatives with metals (Al, Zn) or these parent compounds (compounds before conversion into derivatives), etc. That is, the ring skeletons of the derivatives exemplified here may or may not have substituents. Furthermore, the fourth organic compound may contain two or more ring skeletons. For specific examples of luminescent materials, reference can also be made to the "preferred compounds that can be used as the eighth organic compound" listed in the following (eighth organic compound) column.

[0195] (Organic mixed layer)

[0196] The organic mixed layer of the organic light-emitting element of the present invention contains a first organic compound, a second organic compound and a third organic compound that satisfy condition (a). The organic mixed layer can be set to a structure that does not contain a compound or a metal element that transports charge or energy other than the first organic compound, the second organic compound and the third organic compound. In addition, the organic mixed layer can also be composed of only three compounds, namely the first organic compound, the second organic compound and the third organic compound. In addition, the organic mixed layer can also be composed only of compounds, which are composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms and sulfur atoms. Alternatively, the organic mixed layer can also be composed only of compounds, which are composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms and nitrogen atoms.

[0197] The content of the first organic compound contained in the organic mixed layer is preferably set to 1% by weight or more of the organic mixed layer, for example, it can be set to 10% by weight or more, 20% by weight or more, 30% by weight or more, 50% by weight or more, or 80% by weight or more. In addition, it is preferably set to 99% by weight or less of the organic mixed layer, for example, it can be set to 90% by weight or less, and it can also be set to 70% by weight or less, 50% by weight or less, 30% by weight or less, or 20% by weight or less depending on the situation.

[0198] The content of the second organic compound contained in the organic mixed layer is preferably set to 1% by weight or more of the organic mixed layer, more preferably set to 10% by weight or more, further preferably set to 15% by weight or more, and further preferably set to 20% by weight or more. In addition, it can be set to 25% by weight or more, 45% by weight or more, or 50% by weight or more. In addition, it is preferably set to 95% by weight or less of the organic mixed layer, for example, it can be set to 80% by weight or less, 60% by weight or less, and can also be set to 50% by weight or less, 30% by weight or less, or 20% by weight or less depending on the situation.

[0199] The content of the third organic compound contained in the organic mixed layer is preferably set to 0.01% by weight or more of the organic mixed layer, for example, it can be set to 0.1% by weight or more, or 1% by weight or more. Furthermore, it is preferably set to 30% by weight or less of the organic mixed layer, for example, it can be set to 20% by weight or less, 10% by weight or less, or 5% by weight or less.

[0200] The organic mixed layer can be defined by using the slope of the concentration quenching rate constant of the third organic compound as a parameter. Also, the organic mixed layer can be defined by using the slope of the concentration quenching rate constant of the second organic compound as a parameter.

[0201] The content of the second organic compound in the organic mixed layer is preferably greater than the content of the third organic compound. Furthermore, the content of the first organic compound in the organic mixed layer is preferably greater than the content of the third organic compound. The content of the second organic compound in the organic mixed layer may be greater than the content of the first organic compound, may be less than the content of the first organic compound, or may be the same.

[0202] For example, the composition of the organic mixed layer may be as follows: the first organic compound is 10 to 70% by weight, the second organic compound is 10 to 80% by weight, and the third organic compound is 0.1 to 30% by weight. Also, the composition of the organic mixed layer may be as follows: the first organic compound is 20 to 45% by weight, the second organic compound is 50 to 75% by weight, and the third organic compound is 5 to 20% by weight.

[0203] The types and contents of the first organic compound, the second organic compound, and the third organic compound of the organic mixed layer preferably satisfy specific conditions. For example, when the total weight of the first organic compound, the second organic compound, and the third organic compound contained in the organic mixed layer is set to 100 weight %, the content of the second organic compound is set to A weight %, and the content of the third organic compound is set to B weight %, in the present invention, A and B are preferably determined to satisfy the following conditions. In addition, the wavelength of the excitation light used for the optical excitation described below is preferably 300 nm or more, for example, 337 nm can be used. In order to reduce the measurement error, it is preferred to measure with a film thickness having sufficient absorbance, for example, the film thickness can be set to 50 nm.

[0204] (1) Luminescence quantum yield φ generated by light excitation of a co-deposited film of the second organic compound and the first organic compound (content of the second organic compound in the co-deposited film = A wt %) PL2 (A) Luminescence quantum yield φ generated by light excitation of a co-deposited film of the third organic compound and the first organic compound (content of the third organic compound in the co-deposited film = A wt %) PL3 (A) satisfies the following relationship.

[0205] φ PL2 (A)>φ PL3 (A)

[0206] (2) Luminescence quantum yield φ generated by light excitation of a co-deposited film of the third organic compound and the first organic compound (content of the third organic compound in the co-deposited film = B wt %) PL3 (B) The light emission quantum yield φ generated by the photoexcitation of the single film of the third organic compound PL3 (100) satisfies the following relationship.

[0207] φ PL3 (B)>X%

[0208] φ PL3 (100)<X%

[0209] In the above (1), A is preferably selected from the range of 15 to 75 weight %, and the lower limit includes 15 weight % or more, 20 weight % or more, 25 weight % or more, and 30 weight % or more. The upper limit includes 75 weight % or less, 60 weight % or less, 50 weight % or less, and 40 weight % or less. B is preferably selected from the range of 0.01 to 30 weight %, and the lower limit includes 0.01 weight % or more, 0.1 weight % or more, 0.5 weight % or more, 1 weight % or more, 5 weight % or more, 10 weight % or more, and 15 weight % or more. And, the upper limit includes 20 weight % or less, 25 weight % or less, and 30 weight % or less. X includes 20 to 100 %, 30 to 100 %, and 40 to 100 %, and preferably includes 50 to 100 %, 60 to 100 %, 70 to 100 %, and 80 to 100 %. φ PL3 (100) includes aspects of less than 30%, less than 25%, less than 20%, less than 15%, and less than 10%.

[0210] By selecting the types and contents of the first organic compound, the second organic compound, and the third organic compound to satisfy the relationship between (1) and (2) above to form an organic mixed layer, the life of the organic light-emitting element can be effectively extended. Such a combination of the first organic compound, the second organic compound, and the third organic compound may include, for example, a combination of mCBP, 4CzIPN-Me, and 4CzTPN. In this case, the light emission quantum yield φ generated by the light excitation of the single film of the third organic compound is PL3 (100) is 8%, and the light emission quantum yield φ generated by light excitation of the co-deposited film of the third organic compound and the first organic compound (content of the third organic compound = 5 wt%) PL3 (5) is 52%. Also, the light emission quantum yield φ generated by light excitation of the co-deposited film of the second organic compound and the first organic compound (content of the second organic compound = 50 wt%) is PL2 (50) greater than the light emission quantum yield φ generated by light excitation of the co-deposited film of the third organic compound and the first organic compound (content of the third organic compound = 50 wt%) PL3 (50) Other combinations that can satisfy the relationship between (1) and (2) above may include, for example, a combination of mCBP, 4CzIPN, and 4CzTPN.

[0211] The organic mixed layer may be formed by co-depositing the first organic compound, the second organic compound, and the third organic compound, or may be formed by using a solution obtained by dissolving the first organic compound, the second organic compound, and the third organic compound and applying the solution. When the organic mixed layer is formed by co-deposition, two or more of the first organic compound, the second organic compound, and the third organic compound may be mixed in advance and placed in a tank or the like as a deposition source, and the organic mixed layer may be formed by co-deposition using the deposition source. For example, a deposition source may be prepared by mixing the second organic compound and the third organic compound in advance, and the deposition source and the deposition source of the first organic compound may be co-deposited to form the organic mixed layer.

[0212] <Second aspect of organic light emitting device>

[0213] The organic light emitting element of the second aspect of the present invention is an organic light emitting element having an organic mixed layer, wherein the organic mixed layer comprises a fifth organic compound, a sixth organic compound, a seventh organic compound and an eighth organic compound. The fifth organic compound, the sixth organic compound, the seventh organic compound and the eighth organic compound satisfy the following conditions (b) and (c).

[0214] Condition (b)E S1 (D)>E S1 (E) or E S1 (D)>E S1 (F)

[0215] Condition (c)E S1 (E)>E S1 (F)>E S1 (G)

[0216] Here, E S1 (D) represents the lowest excited singlet energy level of the fifth organic compound, E S1 (E) represents the lowest excited singlet energy level of the sixth organic compound, E S1 (F) represents the lowest excited singlet energy level of the seventh organic compound, E S1 (G) represents the lowest excited singlet energy level of the eighth organic compound. In the following description, the organic light-emitting device according to the second aspect may be referred to as a "second organic light-emitting device".

[0217] The sixth organic compound is a delayed fluorescent material. Furthermore, the seventh organic compound is a delayed fluorescent material having a structure different from that of the sixth organic compound. For the definition of “delayed fluorescent material”, the description in the above section <First aspect of the organic light emitting device> can be referred to.

[0218] The difference between the lowest excited singlet energy level of the 6th organic compound and the lowest excited triplet energy level at 77K, ΔE ST It is preferably 0.3 eV or less, more preferably 0.25 eV or less, more preferably 0.2 eV or less, more preferably 0.15 eV or less, further preferably 0.1 eV or less, further preferably 0.07 eV or less, further preferably 0.05 eV or less, further preferably 0.03 eV or less, and particularly preferably 0.01 eV or less.

[0219] The difference between the lowest excited singlet energy level of the 7th organic compound and the lowest excited triplet energy level at 77K, ΔE ST It is preferably 0.3 eV or less, more preferably 0.25 eV or less, more preferably 0.2 eV or less, more preferably 0.15 eV or less, further preferably 0.1 eV or less, further preferably 0.07 eV or less, further preferably 0.05 eV or less, further preferably 0.03 eV or less, and particularly preferably 0.01 eV or less.

[0220] If ΔE ST If the ΔE is small, it is easy to reverse intersystem crossing from the excited singlet state to the excited triplet state due to the absorption of thermal energy, and thus it functions as a thermally activated delayed fluorescent material. The thermally activated delayed fluorescent material absorbs the heat emitted by the device and relatively easily reverses intersystem crossing from the excited triplet state to the excited singlet state, thereby enabling the excited triplet state to contribute to luminescence with good energy efficiency. ST The measurement method can refer to the description in the above-mentioned column "First aspect of organic light-emitting element".

[0221] (Fifth organic compound)

[0222] The fifth organic compound is an organic compound having a lower excited singlet energy greater than that of the seventh organic compound. The fifth organic compound is preferably an organic compound having a lower excited singlet energy greater than that of both the sixth organic compound and the seventh organic compound. The fifth organic compound has a function as a host material responsible for transporting a carrier or a function of confining the energy of the eighth organic compound in the compound. Thus, the eighth organic compound can efficiently convert the energy generated by the recombination of holes and electrons within the molecule and the energy received from the fifth organic compound, the sixth organic compound and the seventh organic compound into luminescence, thereby realizing an organic light-emitting element with high luminescence efficiency.

[0223] Furthermore, the fifth organic compound is preferably an organic compound that has hole transport capability, electron transport capability, prevents the emission of light at a long wavelength, and has a high glass transition temperature. Furthermore, in a preferred aspect of the present invention, the fifth organic compound is selected from compounds that do not emit delayed fluorescence. For examples of preferred compounds that can be used as the fifth organic compound, reference can be made to the examples of "preferred compounds that can be used as the first organic compound" listed in the column (first organic compound) above.

[0224] (Sixth organic compound and seventh organic compound)

[0225] The sixth organic compound is a delayed fluorescence material having a lower minimum excited singlet energy than the seventh organic compound. The sixth organic compound may be a compound capable of emitting delayed fluorescence under certain conditions, and the second organic light emitting element of the present invention does not necessarily need to emit delayed fluorescence from the sixth organic compound.

[0226] The lowest excited singlet energy of the sixth organic compound may be greater than, less than, or the same as that of the fifth organic compound, but is preferably less than that of the fifth organic compound. Thus, in the second organic light-emitting element of the present invention, the sixth organic compound can receive energy from the fifth organic compound in an excited singlet state and transition to an excited singlet state. Furthermore, the sixth organic compound can receive energy from the fifth organic compound in an excited triplet state and transition to an excited triplet state. Because the ΔE of the sixth organic compound is ST Since the sixth organic compound in the triplet excited state is small, reverse intersystem crossing to the sixth organic compound in the singlet excited state is easy. The sixth organic compound in the singlet excited state generated by these pathways gives energy to the seventh organic compound, causing the seventh organic compound to transition to the singlet excited state.

[0227] The seventh organic compound is a delayed fluorescence material having a minimum excited singlet energy lower than that of the fifth organic compound and the sixth organic compound. The seventh organic compound only needs to be a compound capable of emitting delayed fluorescence under certain conditions, and the second organic light-emitting element of the present invention does not necessarily need to emit delayed fluorescence from the seventh organic compound. The seventh organic compound receives energy from the fifth organic compound and the sixth organic compound in the excited singlet state and the sixth organic compound in the excited singlet state through reverse intersystem crossing from the excited triplet state to the excited singlet state, and transitions to the excited singlet state. In addition, because the ΔE of the seventh organic compound is ST Since the excited singlet state of the 7th organic compound is small, the reverse intersystem crossing to the excited singlet state of the 7th organic compound is easy. The excited singlet state of the 7th organic compound generated by these pathways imparts energy to the 8th organic compound so that the 8th organic compound transitions to the excited singlet state. The excited singlet state of the 8th organic compound emits fluorescence when it returns to the ground state.

[0228] The delayed fluorescent material used as the seventh organic compound is not particularly limited as long as it can receive energy from the fifth organic compound and the sixth organic compound and emit light. In a preferred aspect of the present invention, the compounds are selected and combined so that there is an overlap between the emission wavelength region of the sixth organic compound and the absorption wavelength region of the seventh organic compound. In particular, it is preferred that the edge of the emission spectrum of the sixth organic compound on the long wavelength side overlaps the edge of the absorption spectrum of the seventh organic compound on the short wavelength side.

[0229] The sixth organic compound and the seventh organic compound may use a known delayed fluorescent material. In addition, an unknown delayed fluorescent material may be used. For examples of compounds that can be used as delayed fluorescent materials for the sixth organic compound and the seventh organic compound, reference may be made to the examples of compounds of delayed fluorescent materials listed in the above column (the second organic compound and the third organic compound).

[0230] The delayed fluorescent material used as the sixth organic compound of the present invention and the delayed fluorescent material used as the seventh organic compound are selected and combined to satisfy the condition (c). A preferred aspect of the present invention may include an aspect in which the sixth organic compound and the seventh organic compound are selected and combined from delayed fluorescent materials having the same basic skeleton. For example, the sixth organic compound and the seventh organic compound may be selected and used from delayed fluorescent materials having a benzonitrile structure represented by the above general formula (1). Furthermore, the sixth organic compound and the seventh organic compound may be selected and used from delayed fluorescent materials represented by the above general formula (2).

[0231] (8th organic compound)

[0232] The eighth organic compound is an organic compound having a lowest excited singlet energy lower than that of the fifth organic compound, the sixth organic compound, and the seventh organic compound, and is preferably an organic compound having luminescence (luminescent material). When the eighth organic compound is a luminescent material, the organic light-emitting element emits light from the eighth organic compound. The luminescence may include any one of fluorescence, delayed fluorescence, and phosphorescence, but the largest component of the light emitted from the organic light-emitting element is preferably the light emitted from the eighth organic compound.

[0233] The luminescent material used as the 8th organic compound is not particularly limited as long as it can receive energy from the 5th organic compound, the 6th organic compound, and the 7th organic compound and emit light, and can be any one of a fluorescent material, a delayed fluorescent material, and a phosphorescent material. When the 8th organic compound is a fluorescent material, it receives energy from the 5th organic compound, the 6th organic compound, the 7th organic compound in the excited singlet state, and the 6th organic compound and the 7th organic compound that have undergone reverse intersystem crossing from the excited triplet state to become an excited singlet state, and transitions to the excited singlet state. The generated excited singlet state emits fluorescence when it returns to the ground state later. Moreover, even when the 8th organic compound is a delayed fluorescent material or a phosphorescent material, it can emit light using the energy received from the 5th organic compound, the 6th organic compound, and the 7th organic compound. As long as the 8th organic compound satisfies condition (c), two or more types can be used. For example, it is possible to emit light of a desired color by using two or more 8th organic compounds with different luminescent colors at the same time. When two or more eighth organic compounds are used simultaneously, the lowest excited singlet energy levels of the eighth organic compounds may be the same or different, but are preferably different.

[0234] Examples of the eighth organic compound may include anthracene derivatives, naphthacene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, Derivatives, rubrene derivatives, coumarin derivatives, pyran derivatives, stilbene derivatives, fluorene derivatives, anthracene derivatives, pyrromethene derivatives, terphenyl derivatives, sub-terphenyl derivatives, fluoranthene derivatives, amine derivatives, quinacridone derivatives, oxadiazole derivatives, malononitrile derivatives, pyran derivatives, carbazole derivatives, julolidine derivatives, thiazole derivatives, derivatives with metals (Al, Zn) or these parent compounds (compounds before conversion into derivatives), etc. That is, the ring skeleton of the derivatives exemplified here may have a substituent or may not have a substituent. In addition, the eighth organic compound may contain two or more ring skeletons.

[0235] In the present invention, the maximum emission wavelength of the compound that can be used as the eighth organic compound is not particularly limited. Therefore, a luminescent material having a maximum emission wavelength in the visible region (380 to 780 nm) or a luminescent material having a maximum emission wavelength in the infrared region (780 nm to 1 mm) can be appropriately selected and used. For example, a luminescent material having a maximum emission wavelength in the range of 500 to 780 nm in the region of 380 to 780 nm can be selected and used. For example, a luminescent material having a maximum emission wavelength in the green range of 500 to 570 nm or a luminescent material having a maximum emission wavelength in the red range of 650 to 780 nm can be selected and used.

[0236] Preferred compounds that can be used as the eighth organic compound are listed below for each luminescent color. In the structural formulas of the following exemplary compounds, Et represents an ethyl group, and i-Pr represents an isopropyl group.

[0237] (1) Green luminescent compounds

[0238] [Chemical formula 31]

[0239]

[0240] [Chemical formula 32]

[0241]

[0242] [Chemical formula 33-1]

[0243]

[0244] [Chemical formula 33-2]

[0245]

[0246] [Chemical formula 34]

[0247]

[0248] (2) Red luminescent compound [Chemical formula 35]

[0249]

[0250] [Chemical formula 36]

[0251]

[0252] [Chemical formula 37]

[0253]

[0254] [Chemical formula 38]

[0255]

[0256] [Chemical formula 39]

[0257]

[0258] (3) Blue light-emitting compound [Chemical formula 40]

[0259]

[0260] [Chemical formula 41]

[0261]

[0262] [Chemical formula 42]

[0263]

[0264] [Chemical formula 43]

[0265]

[0266] [Chemical formula 44]

[0267]

[0268] [Chemical formula 45]

[0269]

[0270] [Chemical formula 46]

[0271]

[0272] [Chemical formula 47-1]

[0273]

[0274] [Chemical formula 47-2]

[0275]

[0276] [Chemical formula 48-1]

[0277]

[0278] [Chemical formula 48-2]

[0279]

[0280] (4) Yellow luminescent compounds

[0281] [Chemical formula 49]

[0282]

[0283] In addition to the above-mentioned compounds of each luminescent color, the following compounds can also be used as the eighth organic compound.

[0284] [Chemical formula 50]

[0285]

[0286] (Organic mixed layer)

[0287] The organic mixed layer of the second organic light-emitting element of the present invention contains the fifth organic compound, the sixth organic compound, the seventh organic compound and the eighth organic compound that satisfy conditions (b) and (c). The organic mixed layer can be set to a structure that does not contain compounds or metal elements that transport charge or energy other than the fifth organic compound, the sixth organic compound, the seventh organic compound and the eighth organic compound. In addition, the organic mixed layer can also be composed of only four compounds, namely the fifth organic compound, the sixth organic compound, the seventh organic compound and the eighth organic compound. In addition, the organic mixed layer can also be composed only of compounds, which are composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms and sulfur atoms. Alternatively, the organic mixed layer can also be composed only of compounds, which are composed only of atoms selected from the group consisting of carbon atoms, hydrogen atoms and nitrogen atoms.

[0288] The content of the fifth organic compound contained in the organic mixed layer is preferably set to 1% by weight or more of the organic mixed layer, for example, it can be set to 10% by weight or more, 20% by weight or more, 30% by weight or more, 50% by weight or more, or 80% by weight or more. In addition, it is preferably set to 99% by weight or less of the organic mixed layer, for example, it can be set to 90% by weight or less, and it can also be set to 70% by weight or less, 50% by weight or less, 30% by weight or less, or 20% by weight or less depending on the situation.

[0289] The content of the sixth organic compound contained in the organic mixed layer is preferably set to 1% by weight or more of the organic mixed layer, for example, it can be set to 10% by weight or more, 25% by weight or more, 45% by weight or more, or 50% by weight or more. In addition, it is preferably set to 95% by weight or less of the organic mixed layer, for example, it can be set to 80% by weight or less, 60% by weight or less, and it can also be set to 50% by weight or less, 30% by weight or less, or 20% by weight or less depending on the situation.

[0290] The content of the seventh organic compound contained in the organic mixed layer is preferably set to 0.1% by weight or more of the organic mixed layer, for example, it can be set to 1% by weight or more, or 3% by weight or more. Also, it is preferably set to 30% by weight or less of the organic mixed layer, for example, it can be set to 20% by weight or less, 10% by weight or less, or 5% by weight or less.

[0291] The content of the eighth organic compound contained in the organic mixed layer is preferably set to 0.01% by weight or more of the organic mixed layer, for example, it can be set to 0.1% by weight or more, or 1% by weight or more. Also, it is preferably set to 20% by weight or less of the organic mixed layer, for example, it can be set to 10% by weight or less, 5% by weight or less, or 1% by weight or less.

[0292] The organic mixed layer can be defined using the slope of the concentration quenching rate constant of the seventh organic compound as a parameter. Furthermore, the organic mixed layer can also be defined using the slope of the concentration quenching rate constant of the sixth organic compound as a parameter.

[0293] The content of the sixth organic compound in the organic mixed layer is preferably greater than the content of the seventh organic compound. Furthermore, the content of the fifth organic compound in the organic mixed layer is preferably greater than the content of the seventh organic compound. The content of the sixth organic compound in the organic mixed layer may be greater than the content of the fifth organic compound, may be less than the content of the fifth organic compound, or may be the same as the content of the fifth organic compound. The content of the eighth organic compound in the organic mixed layer is preferably less than the content of the fifth organic compound, the content of the sixth organic compound, and the content of the seventh organic compound.

[0294] For example, the composition of the organic mixed layer may be as follows: the fifth organic compound is 10 to 70% by weight, the sixth organic compound is 10 to 80% by weight, the seventh organic compound is 0.1 to 30% by weight, and the eighth organic compound is 0.01 to 10% by weight. Furthermore, the composition of the organic mixed layer may be as follows: the fifth organic compound is 20 to 40% by weight, the sixth organic compound is 40 to 60% by weight, the seventh organic compound is 1 to 10% by weight, and the eighth organic compound is 0.01 to 3% by weight.

[0295] The types and contents of the fifth organic compound, the sixth organic compound, and the seventh organic compound in the compounds constituting the organic mixed layer preferably satisfy specific conditions. For example, when the total weight of the fifth organic compound, the sixth organic compound, and the seventh organic compound contained in the organic mixed layer is set to 100 weight %, the content of the sixth organic compound is set to A weight %, and the content of the seventh organic compound is set to B weight %, in the present invention, A and B are preferably determined to satisfy the following conditions. In addition, the wavelength of the excitation light used for the optical excitation described below is preferably 300 nm or more, for example, 337 nm can be used. In order to reduce the measurement error, it is preferred to measure with a film thickness having sufficient absorbance, for example, the film thickness can be set to 50 nm.

[0296] (1) Luminescence quantum yield φ generated by light excitation of a co-deposited film of the sixth organic compound and the fifth organic compound (content of the sixth organic compound in the co-deposited film = A wt %) PL2 (A) Luminescence quantum yield φ generated by light excitation of a co-deposited film of the seventh organic compound and the fifth organic compound (content of the seventh organic compound in the co-deposited film = A wt %) PL3 (A) satisfies the following relationship.

[0297] φPL2 (A)>φ PL3 (A)

[0298] (2) Luminescence quantum yield φ generated by light excitation of a co-deposited film of the seventh organic compound and the fifth organic compound (content of the seventh organic compound in the co-deposited film = B wt %) PL3 (B) Light emission quantum yield φ generated by photoexcitation of a single film of the seventh organic compound PL3 (100) satisfies the following relationship.

[0299] φ PL3 (B)>X%

[0300] φ PL3 (100)<X%

[0301] In the above (1), A is preferably selected from the range of 15 to 75 weight %, and the lower limit includes 15 weight % or more, 20 weight % or more, 25 weight % or more, and 30 weight % or more. The upper limit includes 75 weight % or less, 60 weight % or less, 50 weight % or less, and 40 weight % or less. B is preferably selected from the range of 0.01 to 30 weight %, and the lower limit includes 0.01 weight % or more, 0.1 weight % or more, 0.5 weight % or more, 1 weight % or more, 5 weight % or more, 10 weight % or more, and 15 weight % or more. And, the upper limit includes 20 weight % or less, 25 weight % or less, and 30 weight % or less. X includes 20 to 100 %, 30 to 100 %, and 40 to 100 %, and preferably includes 50 to 100 %, 60 to 100 %, 70 to 100 %, and 80 to 100 %. φ PL3 (100) includes aspects of less than 30%, less than 25%, less than 20%, less than 15%, and less than 10%.

[0302] By selecting the types and contents of the fifth organic compound, the sixth organic compound, and the seventh organic compound to satisfy the relationship between (1) and (2) above to form an organic mixed layer, the life of the organic light-emitting element can be effectively extended. The combination of the fifth organic compound, the sixth organic compound, and the seventh organic compound may include, for example, a combination of mCBP, 4CzIPN-Me, and 4CzTPN. At this time, the light emission quantum yield φ generated by the light excitation of the single film of the seventh organic compound is PL3 (100) is 8%, and the light emission quantum yield φ generated by light excitation of the co-deposited film of the seventh organic compound and the fifth organic compound (the content of the seventh organic compound = 5 wt%) PL3(5) is 52%. Also, the light emission quantum yield φ generated by light excitation of the co-deposited film of the sixth organic compound and the fifth organic compound (the content of the sixth organic compound = 50 wt %) is PL2 (50) is greater than the light emission quantum yield φ generated by light excitation of the co-deposited film of the seventh organic compound and the fifth organic compound (content of the seventh organic compound = 50 wt%) PL3 (50) Other combinations that can satisfy the relationship between (1) and (2) above may include, for example, a combination of mCBP, 4CzIPN, and 4CzTPN.

[0303] The organic mixed layer can be formed by co-depositing the fifth organic compound, the sixth organic compound, the seventh organic compound, and the eighth organic compound, or by using a solution obtained by dissolving the fifth organic compound, the sixth organic compound, the seventh organic compound, and the eighth organic compound and forming the organic mixed layer by a coating method. When the organic mixed layer is formed by co-deposition, two or more of the fifth organic compound, the sixth organic compound, the seventh organic compound, and the eighth organic compound can be mixed in advance and placed in a tank or the like as a deposition source, and the organic mixed layer is formed by co-deposition using the deposition source. For example, a deposition source can be prepared by mixing with the sixth organic compound and the seventh organic compound in advance, and the deposition source of the fifth organic compound and the deposition source of the eighth organic compound are co-deposited to form the organic mixed layer. Furthermore, a deposition source can be prepared by mixing with the seventh organic compound and the eighth organic compound in advance, and the deposition source of the fifth organic compound and the deposition source of the sixth organic compound are co-deposited to form the organic mixed layer. Alternatively, the sixth organic compound, the seventh organic compound, and the eighth organic compound may be mixed in advance to produce a deposition source, and the deposition source and a deposition source of the fifth organic compound may be used to perform co-deposition, thereby forming the organic mixed layer.

[0304] <Layer Structure of First Organic Light-Emitting Element and Second Organic Light-Emitting Element>

[0305] By forming an organic mixed layer containing the first organic compound, the second organic compound and the third organic compound satisfying condition (a), an excellent organic light-emitting element such as an organic photoluminescent element (organic PL element) or an organic electroluminescent element (organic EL element) can be provided. Furthermore, by forming an organic mixed layer containing the fifth organic compound, the sixth organic compound, the seventh organic compound and the eighth organic compound satisfying conditions (b) and (c), an excellent organic light-emitting element such as an organic photoluminescent element (organic PL element) or an organic electroluminescent element (organic EL element) can be provided.

[0306] The organic mixed layer can be formed as the light-emitting layer of the organic light-emitting element, or can be formed as a layer in contact with the light-emitting layer, such as an exciton generation layer or an exciplex layer, or can be formed on the light-emitting layer via a layer. In the present invention, in particular, by forming the organic mixed layer as a layer in contact with the light-emitting layer, a long life and high light-emitting efficiency can also be achieved. In addition, the light-emitting layer described herein is a layer having a light-emitting intensity greater than that of the organic mixed layer in contact with the light-emitting layer, and the organic mixed layer can be a non-light-emitting layer or a light-emitting layer. When the organic mixed layer is an exciton generation layer, the light-emitting material of the light-emitting layer in contact with the organic mixed layer preferably has a lower lowest excited singlet energy level than the first organic compound and the second organic compound in the first organic light-emitting element, and more preferably has a lower lowest excited singlet energy level than the third organic compound. In addition, the light-emitting material of the light-emitting layer in contact with the organic mixed layer preferably has a lower lowest excited singlet energy level than the fifth organic compound and the sixth organic compound in the second organic light-emitting element, and more preferably has a lower lowest excited singlet energy level than the seventh organic compound. As a result, the excitons generated in the organic mixed layer can be efficiently transferred to the light-emitting layer. When the organic mixed layer is formed as a light-emitting layer, its thickness can be set to 1 to 15 nm, 2 to 10 nm, or 3 to 7 nm, and when the organic mixed layer is formed as a layer different from the light-emitting layer, its thickness can be set to 1 to 60 nm, 5 to 50 nm, or 10 to 40 nm. The light-emitting layer may also be composed of only the organic mixed layer.

[0307] The organic photoluminescent element has a structure in which at least a light-emitting layer is formed on a substrate. Furthermore, the organic electroluminescent element has a structure in which at least an anode, a cathode, and an organic layer is formed between the anode and the cathode. The organic layer includes at least a light-emitting layer, which may be formed only by the light-emitting layer, or may have more than one organic layer in addition to the light-emitting layer. Such other organic layers may include a hole transport layer, a hole injection layer, an electron blocking layer, a hole blocking layer, an electron injection layer, an electron transport layer, an exciton blocking layer, and the like. The hole transport layer may be a hole injection and transport layer having a hole injection function, and the electron transport layer may be an electron injection and transport layer having an electron injection function. The structure of the specific organic electroluminescent element is shown in Figure 1 In. Figure 1 , 1 represents a substrate, 2 represents an anode, 3 represents a hole injection layer, 4 represents a hole transport layer, 5 represents a light emitting layer, 6 represents an electron transport layer, and 7 represents a cathode.

[0308] When the organic light-emitting element of the present invention is a multi-wavelength light-emitting organic light-emitting element, the light emission of the shortest wavelength can be set to not include delayed fluorescence. In particular, as the first organic compound or the fifth organic compound, a material that is not a delayed fluorescence material can be selected, or a light-emitting material whose lowest excited singlet energy of the light-emitting material of the light-emitting layer in contact with the organic mixed layer is lower than that of the second organic compound, the sixth organic compound, or the seventh organic compound can be selected.

[0309] Hereinafter, each member of the organic electroluminescent element and each layer other than the light-emitting layer will be described. In the following description, the organic mixed layer is referred to as the light-emitting layer.

[0310] Substrate:

[0311] In some embodiments, the organic electroluminescent element of the present invention is supported by a substrate, wherein the substrate is not particularly limited and may be any of those substrates that have been commonly used in organic electroluminescent elements, such as those formed of glass, transparent plastic, quartz, and silicon.

[0312] anode:

[0313] In some embodiments, the anode of the organic electroluminescent device is made of a metal, an alloy, a conductive compound, or a combination thereof. In some embodiments, the metal, alloy, or conductive compound has a large work function (above 4 eV). In some embodiments, the metal is Au. In some embodiments, the conductive transparent material is selected from CuI, indium tin oxide (ITO), SnO 2 In some embodiments, an amorphous material such as IDIXO (In 2 O 3 -ZnO) and the like. In some embodiments, the anode is a thin film. In some embodiments, the thin film is made by vapor deposition or sputtering. In some embodiments, the film is patterned by photolithography. In some embodiments, when the pattern may not require high precision (for example, about 100 μm or more), the pattern can be formed by vapor deposition or sputtering of the electrode material using a mask of the desired shape. In some embodiments, when a coating material (such as an organic conductive compound) can be applied, a wet film formation method such as a printing method and a coating method is used. In some embodiments, when the emitted light passes through the anode, the transmittance of the anode is greater than 10%, and the sheet resistance of the anode is less than hundreds of ohms per square. In some embodiments, the thickness of the anode is 10 to 1,000 nm. In some embodiments, the thickness of the anode is 10 to 200 nm. In some embodiments, the thickness of the anode varies depending on the material used.

[0314] cathode:

[0315] In some embodiments, the cathode is made of a metal (less than 4 eV) (called an electron injection metal) having a small work function, an alloy, a conductive compound, or a combination thereof. In some embodiments, the electrode material is selected from sodium, sodium-potassium alloy, magnesium, lithium, a magnesium-copper mixture, a magnesium-silver mixture, a magnesium-aluminum mixture, a magnesium-indium mixture, an aluminum-aluminum oxide (Al 2 O 3 ) mixture, indium, lithium-aluminum mixture and rare earth metal. In some embodiments, a mixture of an electron injecting metal and a second metal is used, and the second metal is a stable metal with a larger work function than the electron injecting metal. In some embodiments, the mixture is selected from magnesium-silver mixture, magnesium-aluminum mixture, magnesium-indium mixture, aluminum-aluminum oxide (Al 2 O 3 ) mixture, lithium-aluminum mixture and aluminum. In some embodiments, the mixture increases electron injection characteristics and durability against oxidation. In some embodiments, the cathode is manufactured by forming the electrode material into a thin film by vapor deposition or sputtering. In some embodiments, the sheet resistance of the cathode is less than hundreds of ohms per square. In some embodiments, the thickness of the cathode is in the range of 10nm to 5μm. In some embodiments, the thickness of the cathode is in the range of 50 to 200nm. In some embodiments, in order to transmit the emitted light, any one of the anode and cathode of the organic electroluminescent element is transparent or translucent. In some embodiments, the transparent or translucent electroluminescent element enhances the luminous brightness.

[0316] In some embodiments, the cathode is formed with a conductive transparent material as described for the anode to form a transparent or translucent cathode. In some embodiments, the element comprises an anode and a cathode that are both transparent or translucent.

[0317] Injection layer:

[0318] The injection layer is a layer between the electrode and the organic layer. In some embodiments, the injection layer reduces the driving voltage and enhances the luminous brightness. In some embodiments, the injection layer includes a hole injection layer and an electron injection layer. The injection layer can be configured between the anode and the light-emitting layer or the hole transport layer, and between the cathode and the light-emitting layer or the electron transport layer. In some embodiments, there is an injection layer. In some embodiments, there is no injection layer.

[0319] Preferred examples of compounds that can be used as hole injection materials are included below.

[0320] [Chemical formula 51]

[0321]

[0322] Next, preferred examples of compounds that can be used as electron injecting materials are included.

[0323] [Chemical formula 52]

[0324]

[0325] Barrier layer:

[0326] The blocking layer is a layer that can inhibit the diffusion of charges (electrons or holes) and / or excitons in the light-emitting layer to the outside of the light-emitting layer. In some embodiments, the electron blocking layer is between the light-emitting layer and the hole transport layer, and inhibits electrons from passing through the light-emitting layer toward the hole transport layer. In some embodiments, the hole blocking layer is between the light-emitting layer and the electron transport layer, and inhibits holes from passing through the light-emitting layer toward the electron transport layer. In some embodiments, the blocking layer inhibits the diffusion of excitons to the outside of the light-emitting layer. In some embodiments, the electron blocking layer and the hole blocking layer constitute an exciton blocking layer. The term "electron blocking layer" or "exciton blocking layer" used in this article includes a layer having the functions of both an electron blocking layer and an exciton blocking layer.

[0327] Hole blocking layer:

[0328] The hole blocking layer functions as an electron transport layer. In some embodiments, the hole blocking layer inhibits holes from reaching the electron transport layer while transporting electrons. In some embodiments, the hole blocking layer enhances the probability of re-bonding of electrons and holes in the light-emitting layer. The material used for the hole blocking layer can be the same material as described for the electron transport layer.

[0329] The following are examples of preferred compounds that can be used in the hole blocking layer.

[0330] [Chemical formula 53]

[0331]

[0332] [Chemical formula 54]

[0333]

[0334] Electron blocking layer:

[0335] The holes are transported by the electron blocking layer. In some embodiments, the electron blocking layer inhibits electrons from reaching the hole transport layer while transporting holes. In some embodiments, the electron blocking layer enhances the probability of re-bonding of electrons and holes in the light-emitting layer. The material used for the electron blocking layer can be the same material as described for the hole transport layer.

[0336] Specific examples of preferred compounds that can be used as electron blocking materials are included below.

[0337] [Chemical formula 55]

[0338]

[0339] Exciton blocking layer:

[0340] The exciton blocking layer inhibits the diffusion of excitons generated by the rebonding of holes and electrons in the light-emitting layer to the charge transport layer. In some embodiments, the exciton blocking layer enables the excitons to be effectively confined in the light-emitting layer. In some embodiments, the luminescence efficiency of the device is enhanced. In some embodiments, the exciton blocking layer is adjacent to the light-emitting layer on either the anode side and the cathode side and on both sides. In some embodiments, when the exciton blocking layer is on the anode side, the layer may be between the hole transport layer and the light-emitting layer and adjacent to the light-emitting layer. In some embodiments, when the exciton blocking layer is on the cathode side, the layer may be between the light-emitting layer and the cathode and adjacent to the light-emitting layer. In some embodiments, the hole injection layer, the electron blocking layer, or the same layer is between the anode and the exciton blocking layer, and the exciton blocking layer is adjacent to the light-emitting layer on the anode side. In some embodiments, the hole injection layer, the electron blocking layer, the hole blocking layer, or the same layer is between the cathode and the exciton blocking layer, and the exciton blocking layer is adjacent to the light-emitting layer on the cathode side. In some embodiments, the exciton blocking layer comprises an excited singlet energy and an excited triplet energy, at least one of which is higher than the excited singlet energy and the excited triplet energy of the light-emitting material, respectively.

[0341] Hole transport layer:

[0342] The hole transport layer comprises a hole transport material. In some embodiments, the hole transport layer is a single layer. In some embodiments, the hole transport layer has multiple layers.

[0343] In some embodiments, the hole transport material has one of the injection or transport characteristics of holes and the blocking characteristics of electrons. In some embodiments, the hole transport material is an organic material. In some embodiments, the hole transport material is an inorganic material. Examples of known hole transport materials that can be used in the present invention include, but are not limited to, triazole derivatives, oxadiazole derivatives, imidazole derivatives, carbazole derivatives, indole and carbazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, dihydropyrazolone derivatives, phenylenediamine derivatives, aromatic amine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styryl anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers and conductive polymer oligomers (especially thiophene oligomers) or combinations thereof. In some embodiments, the hole transport material is selected from porphyrin compounds, aromatic tertiary amines and styrylamine compounds. In some embodiments, the hole transport material is an aromatic tertiary amine compound. The following includes specific examples of preferred compounds that can be used as hole transport materials.

[0344] [Chemical formula 56]

[0345]

[0346] [Chemical formula 57]

[0347]

[0348] [Chemical formula 58]

[0349]

[0350] Electron transport layer:

[0351] The electron transport layer comprises an electron transport material. In some embodiments, the electron transport layer is a single layer. In some embodiments, the electron transport layer has multiple layers.

[0352] In some embodiments, the electron transport material only needs to have the function of transporting electrons, which are injected from the cathode into the light-emitting layer. In some embodiments, the electron transport material also functions as a hole blocking material. Examples of electron transport layers that can be used in the present invention include (but are not limited to) fluorene derivatives substituted by nitro, dibenzoquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenyl methane derivatives, anthraquinone dimethane, anthrone derivatives, oxadiazole derivatives, azole derivatives, oxazine derivatives or combinations thereof or polymers thereof. In some embodiments, the electron transport material is a thiadiazole derivative or a quinoxaline derivative. In some embodiments, the electron transport material is a polymer material. The following includes specific examples of preferred compounds that can be used as electron transport materials.

[0353] [Chemical formula 59]

[0354]

[0355] [Chemical formula 60]

[0356]

[0357] [Chemical formula 61]

[0358]

[0359] [Chemical formula 62]

[0360]

[0361] Furthermore, examples of compounds that are preferable as materials that can be added to each organic layer are included. For example, it is conceivable that the compound can be added as a stabilizing material.

[0362] [Chemical formula 63]

[0363]

[0364] Preferred materials that can be used for organic electroluminescent elements are specifically exemplified, but the materials that can be used in the present invention are not limited to the following exemplified compounds. Furthermore, even compounds exemplified as materials having specific functions can be used as materials having other functions.

[0365] Device:

[0366] In some embodiments, the light emitting layer is incorporated into a device. For example, devices include, but are not limited to, OLED bulbs, OLED lamps, television screens, computer monitors, mobile phones, and tablet computers.

[0367] In some embodiments, an electronic device includes an OLED having an anode, a cathode, and at least one organic layer including a light-emitting layer between the anode and the cathode.

[0368] In some embodiments, the compositions described herein can be incorporated into various light-sensitive or light-activated devices, such as OLEDs or photovoltaic devices. In some embodiments, the compositions can be suitable for promoting charge transfer or energy transfer within the device and / or for use as hole transport materials. The devices include, for example, organic light-emitting diodes (OLEDs), organic integrated circuits (O-ICs), organic field effect transistors (O-FETs), organic thin film transistors (O-TFTs), organic light-emitting transistors (O-LETs), organic solar cells (O-SCs), organic photodetectors, organic photoreceptors, organic field-quenching devices (organic field-quench devices; O-FQDs), light-emitting electrochemical cells (LECs), or organic laser diodes (O-lasers).

[0369] Bulb or Lamp:

[0370] In some embodiments, an electronic device includes an OLED including an anode, a cathode, and at least one organic layer including a light-emitting layer between the anode and the cathode.

[0371] In some embodiments, the device comprises OLEDs of different colors. In some embodiments, the device comprises an array comprising a combination of OLEDs. In some embodiments, the combination of OLEDs is a combination of three colors (e.g., RGB). In some embodiments, the combination of OLEDs is a combination of colors other than red, green, or blue (e.g., orange and yellow-green). In some embodiments, the combination of OLEDs is a combination of two, four, or more colors.

[0372] In some embodiments, the device is an OLED lamp having:

[0373] A circuit substrate having a first surface having a mounting surface and a second surface opposite thereto and defining at least one opening;

[0374] At least one OLED is disposed on the mounting surface and has a structure in which the at least one OLED includes an anode, a cathode, and at least one organic layer including a light-emitting layer between the anode and the cathode and emits light;

[0375] A housing for a circuit substrate; and

[0376] At least one connector is disposed at an end of the housing, and the housing and the connector define a package suitable for mounting on a lighting device.

[0377] In some embodiments, the OLED lamp includes a plurality of OLEDs mounted on a circuit board so that light is emitted in a plurality of directions. In some embodiments, a portion of the light emitted in a first direction is deflected to be emitted in a second direction. In some embodiments, a reflector is used to deflect the light emitted in the first direction.

[0378] Monitor or Screen:

[0379] In some embodiments, the light-emitting layer of the present invention can be used in a screen or display. In some embodiments, the compounds involved in the present invention are deposited onto a substrate using methods including (but not limited to) vacuum evaporation, deposition, vapor deposition or chemical vapor deposition (CVD). In some embodiments, the substrate is a photoplate structure suitable for double-sided etching, providing unique aspect ratio pixels. The screen (which may also be referred to as a mask) is used in a method for manufacturing an OLED display. The corresponding artwork pattern design promotes extremely steep and narrow tie-bars between pixels in the vertical direction, and promotes larger sweeping angle openings in the horizontal direction. Thus, the pixels required for high-definition displays are allowed to be tightly patterned while optimizing chemical vapor deposition onto the TFT backplane.

[0380] Internal patterning of the pixel allows the construction of 3-dimensional pixel openings with varying aspect ratios in the horizontal and vertical directions. In addition, etching in specific areas is suppressed using imaged "strips" or halftone circles within the pixel area until these specific patterns are undercut and leave the substrate. At this point, all pixel areas are processed at the same etching rate, but the depth varies depending on the halftone pattern. Changing the size and spacing of the halftone pattern allows etching to be suppressed at different rates within the pixel, allowing for localized deeper etching required to form steep vertical bevels.

[0381] The preferred material for the deposition mask is invar. Invar is a metal alloy that is cold rolled into long thin sheets in a steel mill. Invar cannot be electrodeposited onto a spin mandrel as a nickel mask. An appropriate and low-cost method for forming the opening area in the mask for vapor deposition is a method based on wet chemical etching.

[0382] In some embodiments, the screen or display pattern is a matrix of pixels on a substrate. In some embodiments, the screen or display pattern is manufactured using lithography (e.g., photolithography and e-beam lithography). In some embodiments, the screen or display pattern is manufactured using wet chemical etching. In other embodiments, the screen or display pattern is manufactured using plasma etching.

[0383] Device manufacturing method:

[0384] OLED displays are generally manufactured by forming a large motherboard and then cutting the motherboard into unit board units. Generally speaking, each unit board on the motherboard is formed by forming a thin film transistor including an active layer and a source electrode / drain electrode on a base substrate, applying a planarization film to the TFT, and sequentially forming a pixel electrode, a light emitting layer, a counter electrode and an encapsulation layer, and cutting from the motherboard.

[0385] OLED displays are generally manufactured by forming a large motherboard and then cutting the motherboard into unit board units. Generally speaking, each unit board on the motherboard is formed by forming a thin film transistor including an active layer and a source electrode / drain electrode on a base substrate, applying a planarization film to the TFT, and sequentially forming a pixel electrode, a light emitting layer, a counter electrode and an encapsulation layer, and cutting from the motherboard.

[0386] In another aspect of the present invention, there is provided a method for manufacturing an organic light emitting diode (OLED) display, the method comprising:

[0387] The process of forming a barrier layer on the base substrate of the mother board;

[0388] A process of forming a plurality of display units from a unit panel unit on the barrier layer;

[0389] forming an encapsulation layer on each of the display units of the unit panel; and

[0390] A process of coating an organic film on the interface portion between the unit plates.

[0391] In some embodiments, the barrier layer is an inorganic film formed of, for example, SiNx, and an edge portion of the barrier layer is covered with an organic film formed of polyimide or acryl. In some embodiments, the organic film helps to gently cut the mother board into unit board units.

[0392] In some embodiments, the thin film transistor (TFT) layer has a light emitting layer, a gate electrode, and a source electrode / drain electrode. Each of the plurality of display units may include a thin film transistor (TFT), a planarization film formed on the TFT layer, and a light emitting unit formed on the planarization film, wherein the organic film applied to the interface portion is formed of the same material as the material of the planarization film and is formed at the same time as the planarization film is formed. In some embodiments, the light emitting unit is connected to the TFT layer with a passivation layer, a planarization film, and an encapsulation layer therebetween, and the encapsulation layer covers and protects the light emitting unit. In some embodiments of the manufacturing method, the organic film contacts neither the display unit nor the encapsulation layer.

[0393] Each of the organic film and the planarization film may include any one of polyimide and acryl. In some embodiments, the barrier layer may be an inorganic film. In some embodiments, the base substrate may be formed of polyimide. The method may further include, before forming a barrier layer on one surface of the base substrate formed of polyimide, mounting a carrier substrate formed of a glass material on another surface of the base substrate, and before cutting along the interface portion, separating the carrier substrate from the base substrate. In some embodiments, the OLED display is a flexible display.

[0394] In some embodiments, the passivation layer is an organic film disposed on the TFT layer to cover the TFT layer. In some embodiments, the planarization film is an organic film formed on the passivation layer. In some embodiments, the planarization film is formed of polyimide or acryl, as is the organic film formed on the edge portion of the barrier layer. In some embodiments, when manufacturing an OLED display, the planarization film and the organic film are formed simultaneously. In some embodiments, the organic film may be formed on the edge portion of the barrier layer so that a portion of the organic film directly contacts the base substrate, and the remaining portion of the organic film contacts the barrier layer while surrounding the edge portion of the barrier layer.

[0395] In some embodiments, the light emitting layer comprises a pixel electrode, an opposite electrode and an organic light emitting layer disposed between the pixel electrode and the opposite electrode. In some embodiments, the pixel electrode is connected to a source electrode / drain electrode of a TFT layer.

[0396] In some embodiments, when a voltage is applied to the pixel electrode via the TFT layer, an appropriate voltage is formed between the pixel electrode and the opposite electrode, whereby the organic light-emitting layer emits light, thereby forming an image. Hereinafter, an image forming unit having a TFT layer and a light-emitting unit is referred to as a display unit.

[0397] In some embodiments, the encapsulation layer that covers the display unit and prevents external moisture from penetrating can be formed to have a thin film encapsulation structure in which an organic film and an inorganic film are alternately stacked. In some embodiments, the encapsulation layer has a thin film encapsulation structure in which a plurality of thin films are stacked. In some embodiments, the organic film applied to the interface portion is spaced apart from each of the plurality of display units. In some embodiments, the organic film is formed so that a portion of the organic film directly contacts the base substrate, and the remaining portion of the organic film contacts the barrier layer while surrounding an edge portion of the barrier layer.

[0398] In one embodiment, the OLED display is flexible and uses a soft base substrate formed of polyimide.In some embodiments, the base substrate is formed on a carrier substrate formed of a glass material, and then the carrier substrate is separated.

[0399] In some embodiments, a barrier layer is formed on a surface of the base substrate on the side opposite to the carrier substrate. In one embodiment, the barrier layer is patterned according to the size of each unit board. For example, while the base substrate is formed over the entire surface of the mother board, the barrier layer is formed according to the size of each unit board, thereby forming a groove at the interface portion between the unit board barrier layers. Each unit board can be cut along the groove.

[0400] In some embodiments, the manufacturing method further includes a process of cutting along the interface portion, wherein a groove is formed in the barrier layer, wherein at least a portion of the organic film is formed in the groove, and the groove does not penetrate into the base substrate. In some embodiments, the TFT layer of each unit board is formed, and a passivation layer (i.e., an inorganic film) and a planarization film (i.e., an organic film) are arranged on the TFT layer to cover the TFT layer. While forming a planarization film formed of, for example, polyimide or acryl, the groove at the interface portion is covered with an organic film formed of, for example, polyimide or acryl. This is when cracking is prevented from occurring by allowing the organic film to absorb impact, which is generated when each unit board is cut along the groove at the interface portion. That is, if the entire barrier layer is completely exposed without an organic film, the impact generated when each unit board is cut along the groove at the interface portion is transferred to the barrier layer, thereby increasing the risk of cracking. However, in one embodiment, because the groove at the interface portion between the barrier layers is covered with an organic film, and the organic film absorbs the impact that would otherwise be transferred to the barrier layer, each unit board can be cut gently, and cracks can be prevented from occurring in the barrier layer. In one embodiment, the organic film covering the groove at the interface portion and the planarization film are spaced apart from each other. For example, if the organic film and the planarization film are connected to each other as a single layer, then because external moisture may penetrate into the display unit via the planarization film and a portion where the organic film remains, the organic film and the planarization film are spaced apart from each other so that the organic film is spaced apart from the display unit.

[0401] In some embodiments, the display unit is formed by forming a light-emitting unit, and an encapsulation layer is disposed on the display unit to cover the display unit. Thus, after the motherboard is completely manufactured, the carrier substrate supporting the base substrate is separated from the base substrate. In some embodiments, when a laser beam is emitted toward the carrier substrate, the carrier substrate is separated from the base substrate due to the difference in thermal expansion coefficient between the carrier substrate and the base substrate.

[0402] In some embodiments, the motherboard is cut into unit board units. In some embodiments, the motherboard is cut along the interface portion between the unit boards by using a cutting machine. In some embodiments, because the groove at the interface portion along which the motherboard is cut is covered with an organic film, the organic film absorbs impact during cutting. In some embodiments, cracking can be prevented from occurring in the barrier layer during cutting.

[0403] In some embodiments, the method reduces the defect rate of the product and stabilizes its quality.

[0404] Another aspect is an OLED display having: a barrier layer formed on a base substrate; a display unit formed on the barrier layer; an encapsulation layer formed on the display unit; and an organic film coated on an edge portion of the barrier layer.

[0405] Example

[0406] The following examples are given to further specifically describe the features of the present invention. The materials, processing contents, processing steps, etc. shown below can be appropriately changed as long as they do not depart from the main purpose of the present invention. Therefore, the scope of the present invention should not be interpreted restrictively by the specific examples shown below. In addition, about the evaluation of luminous properties, source meter (Keithley company system: 2400 series), semiconductor parameter analyzer (Agilent Technologies Japan, Ltd. system: E5273A), optical power meter measuring device (Newport Corporation system: 1930C), spectrometer (Ocean Optics company system: USB2000), spectroradiometer (TOPCON CORPORATION system: SR-3) and streak camera (Hamamatsu Photonics KK system C4334 type) are used for evaluation.

[0407] In the following embodiments, the compounds used as the first organic compound, the second organic compound, and the third organic compound satisfy condition (a), and the compounds used as the fifth organic compound, the sixth organic compound, the seventh organic compound, and the eighth organic compound satisfy conditions (b) and (c).

[0408] [A] Fabrication and evaluation of the first organic light-emitting device

[0409] (Comparative Example 1, Comparative Example 2 and Example 1, Example 2)

[0410] By vacuum deposition method, the vacuum degree is 1×10 -6 Pa laminated the thin films on a glass substrate with an anode composed of indium / tin oxide (ITO) with a film thickness of 100 nm. First, HATCN was formed on ITO with a thickness of 10 nm, Tris-PCz was formed on it with a thickness of 25 nm, and mCBP was formed on it with a thickness of 5 nm. Next, mCBP and 4CzIPN (ΔE measured in toluene solution) were ST =0.05 eV) and 4CzTPN (ΔE measured in toluene solution ST=0.03eV) are co-deposited from different deposition sources at concentrations shown in Table 1 below to form a layer with a thickness of 30nm as a light-emitting layer. Next, SF3TRZ is formed into a hole blocking layer with a thickness of 10nm. Next, SF3TRZ and Liq are co-deposited from different deposition sources to form an electron transport layer with a thickness of 40nm. At this time, SF3TRZ:Liq (weight ratio) is set to 7:3. Moreover, Liq is formed to a thickness of 2nm, and then aluminum (Al) is vapor deposited to a thickness of 100nm to form a cathode. Through the above steps, four organic electroluminescent elements, namely Comparative Example 1, Comparative Example 2, Example 1, and Example 2, were prepared. In addition, mCBP as the first organic compound, 4CzIPN as the second organic compound, and 4CzTPN as the third organic compound satisfy condition (a).

[0411] When power was supplied to each of the manufactured organic electroluminescent elements, delayed fluorescence emission from the third organic compound was observed. 2 The initial driving voltage and the time until the luminous intensity reaches 95% (LT95) are shown in the following Table 1. Compared with Comparative Examples 1 and 2, the driving voltage of Examples 1 and 2 is significantly lower. In addition, from the measurement results of LT95, the life of Comparative Example 1, which does not use the second organic compound, is extremely short, and Comparative Example 2, which increases the concentration of the third organic compound to compensate for this, cannot sufficiently improve the life. On the other hand, in Examples 1 and 2, which use the second organic compound, a significant life improvement effect is observed compared with these comparative examples.

[0412] Except for Comparative Example 1, which has an extremely short life and lacks practical application, the organic electroluminescent elements of Comparative Example 2, Example 1, and Example 2 were measured at 1000 cd / m 2 The external quantum yield of Example 1 is 1.3447 W / m. Compared with Comparative Example 2, the external quantum efficiency of Example 1 in which the concentration of the third organic compound is reduced and the second organic compound is added is greatly improved. On the other hand, Example 2 in which the concentration of the first organic compound is reduced by adding the second organic compound while the concentration of the third organic compound is unchanged from that of Comparative Example 2 has the same external quantum yield as that of Comparative Example 2.

[0413] [Table 1]

[0414]

[0415] (Comparative Example 3)

[0416] For comparison, an organic electroluminescent element of Comparative Example 3 was prepared in the same manner as in Example 1, except that a light-emitting layer composed of a second organic compound (4CzIPN: 95 wt %) and a third organic compound (4CzTPN: 5 wt %) was formed without using the first organic compound. When the performance of the element was evaluated, although the driving voltage was the same as that of Example 1, the life span and external quantum efficiency were significantly inferior to those of Examples 1 and 2.

[0417] (Examples 3 to 5 and Comparative Example 2)

[0418] As shown in Table 2, the organic electroluminescent element of Comparative Example 2 which does not use the second organic compound and the organic electroluminescent elements of Examples 3 to 5 which contain 20 wt % of 4CzIPN as the second organic compound and change the concentration of 4CzTPN as the third organic compound were prepared and the performance was evaluated in the same manner. As shown in the results in Table 2, it was confirmed that the life was extended by 4 to 8 times by using the second organic compound.

[0419] [Table 2]

[0420]

[0421] (Example 1, Example 5, Example 6, Example 7 and Comparative Example 1)

[0422] As shown in Table 3, the organic electroluminescent element of Comparative Example 1 without using the second organic compound and the organic electroluminescent elements of Examples 1, 5, 6, and 7 containing 5 wt% of 4CzTPN as the third organic compound and changing the concentration of 4CzIPN as the second organic compound were prepared, and the performance was evaluated in the same manner. As shown in the results in Table 3, it was confirmed that the life was extended by 16 to 22 times by using the second organic compound. In addition, an organic electroluminescent element containing 5 wt% of 4CzTPN as the third organic compound and 30 wt% of 4CzIPN as the second organic compound was prepared, and the performance was evaluated in the same manner. As a result, LT95 was longer than that of Comparative Example 1 and the driving voltage was smaller. In addition, an organic electroluminescent element containing 5 wt% of 4CzTPN as the third organic compound and 10 wt% of 4CzIPN as the second organic compound was prepared, and the performance was evaluated in the same manner. As a result, LT95 was longer than that of Comparative Example 1, but shorter than that of Example 5.

[0423] [Table 3]

[0424]

[0425] (Example 8, Example 9 and Comparative Example 1)

[0426] As shown in Table 4, the organic electroluminescent element of Comparative Example 1 without using the second organic compound and the organic electroluminescent element containing 5 wt % of 4CzTPN as the third organic compound and using Compound A (ΔE measured by a single layer film) were prepared. ST =0.13 eV) and compound B (ΔE measured with a single layer film ST =0.13 eV) as the second organic compound of Example 8 and Example 9, and the performance evaluation was performed in the same manner. As shown in the results in Table 4, the life can be extended by using the second organic compound, and a significant life improvement effect is confirmed when Compound A is used.

[0427] [Table 4]

[0428]

[0429] (Examples 10 to 12 and Comparative Example 4)

[0430] As shown in Table 5, the organic electroluminescent element of Comparative Example 4 which did not use the second organic compound and the organic electroluminescent elements of Examples 10 to 12 which used Compound C as the third organic compound and varied the concentration of 4CzIPN in the second organic compound were prepared and the performance was evaluated in the same manner. As shown in the results in Table 5, it was confirmed that the lifespan could be extended by using the second organic compound.

[0431] [Table 5]

[0432]

[0433] (Example 13, Example 14 and Comparative Example 5)

[0434] As shown in Table 6, the organic electroluminescent element of Comparative Example 5 without using the second organic compound and the organic electroluminescent element of Comparative Example 5 using the green emitting compound 4CzIPN as the third organic compound and using Compound B and Compound D (ΔE measured by single layer film) were prepared. ST =0.13 eV) as the second organic compound, and the performance evaluation was performed in the same manner. As shown in the results in Table 6, it was confirmed that the lifespan could be extended by using the second organic compound.

[0435] [Table 6]

[0436]

[0437] (Example 5, Example 15 and Comparative Example 1)

[0438] As shown in Table 7, an organic electroluminescent element of Comparative Example 1 not using a second organic compound, an organic electroluminescent element of Example 5 containing 20 wt% of 4CzIPN as a second organic compound and 5 wt% of 4CzTPN as a third organic compound, and an organic electroluminescent element of Example 15 containing 50 wt% of 4CzIPN as a second organic compound and 5 wt% of 4CzTPN-Ph as a third organic compound were prepared and performance evaluation was performed in the same manner. As shown in the results in Table 7, even when the third organic compound was changed to 4CzTPN-Ph, the life improvement effect based on the second organic compound was observed.

[0439] [Table 7]

[0440]

[0441] In addition, an organic electroluminescent element containing 6 weight % of PXZ-TRZ as the second organic compound and 2 weight % of 4CzTPN-Ph as the third organic compound, an organic electroluminescent element containing 0.1 weight % of 4CzIPN as the second organic compound and 0.1 weight % of 4CzTPN-Ph as the third organic compound, and an organic electroluminescent element containing 6 weight % of 4CzIPN as the second organic compound and 5 weight % of 4CzTPN-Ph as the third organic compound were prepared respectively, and their performance was evaluated in the same manner. As a result, LT95 was shorter than that of Example 15.

[0442] (Example 16 and Comparative Example 6)

[0443] By vacuum deposition method, the vacuum degree is 1×10 -6Pa stacked each thin film on a glass substrate formed with an anode composed of indium / tin oxide (ITO) with a film thickness of 100nm. First, HAT CN was formed on ITO with a thickness of 10nm, Tris-PCz was formed thereon with a thickness of 25nm, and mCBP was formed thereon with a thickness of 5nm. Then, mCBP, 4CzIPN and 4CzTPN were co-deposited from different deposition sources at concentrations shown in Table 8 below, respectively, to form an exciton generation layer with a thickness of 30nm. Then, SF3TRZ and DBP were co-deposited from different deposition sources at concentrations shown in Table 8 below, to form a light-emitting layer with a thickness of 5nm. Then, SF3TRZ was formed into a hole blocking layer with a thickness of 5nm. Then, SF3TRZ and Liq were co-deposited from different deposition sources to form an electron transport layer with a thickness of 40nm. At this time, SF3TRZ:Liq (weight ratio) was set to 7:3. Furthermore, Liq was formed to a thickness of 2 nm, and then aluminum (Al) was vapor-deposited to a thickness of 100 nm to form a cathode. Through the above steps, organic electroluminescent elements of Comparative Example 6 and Example 16 were prepared. As shown in the results in Table 8, it was confirmed that the lifetime can be extended by forming an organic mixed layer comprising a first organic compound, a second organic compound, and a third organic compound as an exciton generating layer adjacent to the light-emitting layer.

[0444] [Table 8]

[0445]

[0446] [B] Fabrication and evaluation of the second organic light-emitting device

[0447] (Comparative Example 7, Examples 17 to 20 and Comparative Example 8, Example 21)

[0448] mCBP, 4CzIPN (ΔE measured in toluene solution) ST =0.05 eV), 4CzTPN (ΔE measured in toluene solution ST =0.03eV) and DBP as a red light-emitting material were co-deposited from different deposition sources at concentrations shown in Table 9 below to form a layer with a thickness of 30nm as a light-emitting layer. In addition, seven organic electroluminescent elements, namely Comparative Example 7, Examples 17 to 20, Comparative Example 8, and Example 21, were prepared in the same manner as Example 1. In addition, mCBP as the fifth organic compound, 4CzIPN as the sixth organic compound, 4CzTPN as the seventh organic compound, and DBP as the eighth organic compound satisfied conditions (b) and (c).

[0449] When power was supplied to each of the manufactured organic electroluminescent elements, red fluorescence emission from the eighth organic compound was observed. 2 The initial driving voltage and the time until the luminous intensity reaches 95% (LT95). The results are shown in the following Table 9. From the measurement results of LT95, the life of Comparative Example 7, which does not use the sixth organic compound, is extremely short, and Comparative Example 8, which increases the concentration of the seventh organic compound to compensate for this, cannot sufficiently improve the life. On the other hand, in Examples 17 to 21 using the sixth organic compound, a significant life improvement effect is observed compared to these comparative examples. Moreover, compared with Comparative Examples 7 and 8, the driving voltage of Examples 20 and 21 is significantly lower. In addition, an organic electroluminescent element was prepared by changing the content of 4CzIPN as the sixth organic compound to 10 weight %, and the performance was evaluated in the same manner. As a result, the driving voltage was higher than that of Example 17 and the LT95 was shorter.

[0450] Except for Comparative Example 7, which has an extremely short life and lacks practical application, the remaining organic electroluminescent elements of Examples 17 to 20, Comparative Example 8, and Example 21 were measured at 5000 cd / m 2 As a result of the external quantum yield of , all elements have the same external quantum yield. Therefore, it is confirmed that the life span can be greatly improved while maintaining a high external quantum yield according to the present invention.

[0451] [Table 9]

[0452]

[0453] (Example 22, Example 23 and Comparative Example 7)

[0454] As shown in Table 10, the organic electroluminescent element of Comparative Example 7 without using the sixth organic compound and the organic electroluminescent element of Comparative Example 7 using Compound A (ΔE measured by a single layer film) were prepared. ST =0.13 eV) and compound B (ΔE measured with a single layer film ST =0.13 eV) as the sixth organic compound and the concentration of 4CzTPN as the seventh organic compound was set to 5 wt %, and the performance evaluation was performed in the same manner. As shown in the results in Table 10, it was confirmed that the lifetime was extended by 13 to 41 times by using the sixth organic compound.

[0455] [Table 10]

[0456]

[0457] (Example 24, Example 25 and Comparative Example 9)

[0458] As shown in Table 11, the organic electroluminescent element of Comparative Example 9 without using the sixth organic compound and the organic electroluminescent element of Comparative Example 9 using Compound B and Compound C (ΔE measured by single layer film) were prepared. ST =0.13 eV) as the sixth organic compound, 4CzIPN as the seventh organic compound, and TBRb as the eighth organic compound, which is a yellow luminescent material, were used in Example 24 and Example 25, and the performance was evaluated in the same manner. As shown in the results in Table 11, it was confirmed that the lifetime could be extended by using the sixth organic compound.

[0459] [Table 11] [Chemical formula 64-1]

[0460]

[0461] [Chemical formula 64-2]

[0462]

[0463] Industrial Applicability

[0464] According to the present invention, an organic light-emitting element having high light-emitting efficiency and long life can be provided, and the driving voltage can also be suppressed. Therefore, the present invention has high industrial applicability.

[0465] Explanation of symbols

[0466] 1-substrate, 2-anode, 3-hole injection layer, 4-hole transport layer, 5-light-emitting layer, 6-electron transport layer, 7-cathode.

Claims

1. An organic light-emitting element having an organic mixed layer, wherein the organic mixed layer comprises a first organic compound, a second organic compound and a third organic compound satisfying the following condition (a), wherein: The first organic compound is a compound that does not emit delayed fluorescence, and the second organic compound and the third organic compound are delayed fluorescent materials having different structures from each other. The largest component of the light emitted by the organic light emitting element is the light emitted by the third organic compound. Condition (a) E S1 (A) > E S1 (B) > E S1 (C) In the above formula, E S1 (A) represents the lowest excited singlet energy level of the first organic compound, E S1 (B) represents the lowest excited singlet energy level of the second organic compound, E S1 (C) represents the lowest excited singlet energy level of the third organic compound. 2 . The organic light-emitting element according to claim 1 , which is an organic electroluminescent element, comprising an anode, a cathode, and at least one organic layer including the organic mixed layer between the anode and the cathode.

3. The organic light-emitting element according to claim 1 or 2, wherein: The energy difference ΔE between the lowest excited singlet state of the second organic compound and the lowest excited triplet state at 77K st It is less than 0.3 eV.

4. The organic light emitting element according to any one of claims 1 to 3, wherein The energy difference ΔE between the lowest excited singlet state of the third organic compound and the lowest excited triplet state at 77K st It is less than 0.3 eV.

5. The organic light emitting element according to any one of claims 1 to 4, wherein The content of the second organic compound in the organic mixed layer is greater than the content of the third organic compound.

6. The organic light emitting element according to any one of claims 1 to 5, wherein: The content of the second organic compound in the organic mixed layer is greater than the content of the first organic compound.

7. The organic light emitting element according to any one of claims 1 to 6, wherein: The content of the second organic compound in the organic mixed layer is 15% by weight or more of the organic mixed layer.

8. The organic light emitting element according to any one of claims 1 to 7, wherein: A content of the third organic compound in the organic mixed layer is 10% by weight or less of the organic mixed layer.

9. The organic light emitting element according to any one of claims 1 to 8, wherein: The organic mixed layer does not contain a metal element.

10. The organic light emitting element according to any one of claims 1 to 9, wherein: The organic mixed layer is composed only of a compound composed of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, and sulfur atoms.

11. The organic light emitting element according to any one of claims 1 to 10, wherein: The second organic compound and the third organic compound both contain a dibenzonitrile structure.

12. An organic light emitting element comprising an organic mixed layer, wherein the organic mixed layer comprises a fifth organic compound, a sixth organic compound, a seventh organic compound and an eighth organic compound satisfying the following conditions (b) and (c), The sixth organic compound and the seventh organic compound are delayed fluorescent materials having different structures from each other, The largest component of the light emitted by the organic light emitting element is the light emitted by the eighth organic compound. Condition (b)E S1 (D)>E S1 (E)orE S1 (D)>E S1 (F) Condition (c) E S1 (E) > E S1 (F) > E S1 (G) In the above formula, E S1 (D) represents the lowest excited singlet energy level of the fifth organic compound, E S1 (E) represents the lowest excited singlet energy level of the sixth organic compound, and E S1 (F) represents the lowest excited singlet energy level of the seventh organic compound, E S1 (G) represents the lowest excited singlet energy level of the eighth organic compound. 13 . The organic light-emitting element according to claim 12 , which is an organic electroluminescent element, comprising an anode, a cathode, and at least one organic layer including the organic mixed layer between the anode and the cathode.

14. The organic light emitting element according to claim 12 or 13, wherein: The energy difference ΔE between the lowest excited singlet state and the lowest excited triplet state at 77K of the sixth organic compound st It is less than 0.3 eV.

15. The organic light emitting element according to any one of claims 12 to 14, wherein: The energy difference ΔE between the lowest excited singlet state of the seventh organic compound and the lowest excited triplet state at 77K st It is less than 0.3 eV.

16. The organic light emitting element according to any one of claims 12 to 15, wherein: A content of the sixth organic compound in the organic mixed layer is greater than a content of the seventh organic compound.

17. The organic light emitting element according to any one of claims 12 to 16, wherein: A content of the sixth organic compound in the organic mixed layer is greater than a content of the fifth organic compound.

18. The organic light emitting element according to any one of claims 12 to 17, wherein: A content of the fifth organic compound in the organic mixed layer is greater than a content of the seventh organic compound.

19. The organic light emitting element according to any one of claims 12 to 18, wherein: The content of the fifth organic compound, the content of the sixth organic compound, and the content of the seventh organic compound in the organic mixed layer are all greater than the content of the eighth organic compound.

20. The organic light emitting element according to any one of claims 12 to 19, wherein: The content of the sixth organic compound in the organic mixed layer is 25% by weight or more of the organic mixed layer.

21. The organic light emitting element according to any one of claims 12 to 20, wherein: The content of the seventh organic compound in the organic mixed layer is 25% by weight or less of the organic mixed layer.

22. The organic light emitting element according to any one of claims 12 to 21, wherein: The organic mixed layer does not contain a metal element.

23. The organic light emitting element according to any one of claims 12 to 22, wherein: The organic mixed layer is composed only of a compound composed of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, and sulfur atoms.

24. The organic light emitting element according to any one of claims 12 to 23, wherein: The sixth organic compound and the seventh organic compound both contain a dibenzonitrile structure.

25. The organic light emitting element according to any one of claims 1 to 24, wherein The organic mixed layer is a light-emitting layer.

26. The organic light emitting element according to any one of claims 1 to 24, wherein: The organic mixed layer is formed as a layer different from the light emitting layer.

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