Organic light-emitting element

Abstract

This organic light-emitting element comprises two electrodes and a light-emitting layer disposed between the two electrodes. The light-emitting layer includes a first host material, a second host material, and a guest material. The guest material is a compound having an orientation degree Pz value of 0.1 or less. The first host material is a compound having two or more units AR. The unit AR is a fused polycyclic aromatic group having three or more rings and having no sp3 carbon as a carbon atom constituting a ring. The second host material is a compound represented by formula [1] or [2]. (Ar1 and Ar2 are different groups, Ar1 is selected from aryl groups and the like, and Ar2 is selected from a hydrogen atom, aryl groups, and the like. R1 to R8 are each independently selected from a hydrogen atom, alkyl groups, and the like.)

Description

Organic light-emitting device

[0001] The present invention relates to an organic light-emitting device.

[0002] An organic light-emitting device (sometimes referred to as an "organic electroluminescence device" or an "organic EL device") is an electronic device having a pair of electrodes and a light-emitting layer disposed between these electrodes. By injecting electrons and holes from these pair of electrodes, excitons of a light-emitting organic compound in the light-emitting layer are generated, and when the excitons return to the ground state, the organic light-emitting device emits light. The recent progress of organic light-emitting devices has been remarkable. Since they have low driving voltage, various emission wavelengths, high-speed responsiveness, and can be made thinner and lighter, their applications to various devices have been advancing, and research and development for further improving the device characteristics have also been actively conducted.

[0003] One of the methods is to improve the structure of the light-emitting layer. Patent Document 1 describes an organic light-emitting device having a light-emitting layer composed of three types of compounds.

[0004] Japanese Unexamined Patent Application Publication No. 2024-46619

[0005] The organic EL device disclosed in Patent Document has room for further improvement in luminous efficiency and durability characteristics.

[0006] The present invention has been made to solve the above problems, and provides an organic light-emitting device excellent in luminous efficiency and durability characteristics.

[0007] The organic light-emitting device of the present invention is an organic light-emitting device having two electrodes and a light-emitting layer disposed between the two electrodes, wherein the light-emitting layer includes a first host material, a second host material, and a guest material, the guest material is a compound having an orientation degree Pz value of 0.1 or less, the first host material is a compound having two or more unit ARs, and the unit AR is a condensed polycyclic aromatic group having three or more rings without carbon as a carbon atom constituting the ring ３ and having no carbon, and the second host material is a compound represented by the following general formula [1] or general formula [2].

[0008]

[0009] (In general formula [1] or general formula [2], Ar １ and Ar ２ These are different groups, Ar １ Ar is selected from substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups. ２ R is selected from a hydrogen atom, a deuterium atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ ~R ８ Each of these is independently selected from hydrogen atoms, deuterium atoms, halogen atoms, cyano groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted silyl groups, substituted or unsubstituted aryl groups consisting of two or fewer rings, and substituted or unsubstituted heteroaryl groups consisting of two or fewer rings.

[0010] According to the present invention, it is possible to provide an organic light-emitting element with excellent luminous efficiency and durability.

[0011] This is a schematic cross-sectional view showing an example of pixels in a display device according to this embodiment. This is a schematic cross-sectional view of an example of a display device according to this embodiment. This is a schematic diagram showing an example of a display device according to this embodiment. This is a schematic diagram showing an example of an imaging device according to this embodiment. This is a schematic diagram showing an example of an electronic device according to this embodiment. This is a schematic diagram showing an example of a display device according to this embodiment. This is a schematic diagram showing an example of a foldable display device according to this embodiment. This is a schematic diagram showing an example of a lighting device according to this embodiment. This is a schematic diagram showing an example of an automobile having vehicle lighting equipment according to this embodiment. This is a schematic diagram showing an example of an automobile having vehicle lighting equipment according to this embodiment. This is a schematic diagram showing an example of a wearable device according to this embodiment. This is a schematic diagram showing an example of a wearable device according to this embodiment, with an imaging device. This is a schematic diagram of an HMD (head-mounted display) as a display device according to this embodiment. This is a schematic diagram of an HMD (head-mounted display) as a display device according to this embodiment. This is a schematic diagram showing an example of an image forming apparatus according to this embodiment. This is a schematic diagram showing an example of an exposure light source for an image forming apparatus according to this embodiment. This is a schematic diagram showing an example of an exposure light source for an image forming apparatus according to this embodiment.

[0012] This embodiment is a technology for providing an organic light-emitting element with excellent luminous efficiency and durability. Generally, improving the light-emitting layer configuration is one way to provide excellent device characteristics. One example is a ternary light-emitting layer configuration consisting of two types of host material and a guest material. In this configuration, excellent device characteristics can be achieved by selecting materials to produce a synergistic effect, taking into account the characteristics of each material.

[0013] The characteristics of the light-emitting layer configuration in this embodiment are described below. In this specification, unless otherwise specified, specific examples of substituents are as follows.

[0014] The alkyl group may be an alkyl group having 1 to 20 carbon atoms. Examples include, but are not limited to, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a tert-butyl group, a sec-butyl group, an octyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, etc.

[0015] The aryl group may be any aryl group having 6 to 20 carbon atoms. Examples include, but are not limited to, phenyl, naphthyl, indenyl, biphenyl, terphenyl, fluorenyl, phenanthryl, fluoranthenyl, and triphenylenyl groups.

[0016] The heteroaryl group may be any heteroaryl group having 3 to 20 carbon atoms. Examples include, but are not limited to, pyridyl, pyrimidyl, pyrazyl, triazolyl, oxazolyl, oxadiazolyl, thiazolyl, thiadiazolyl, carbazolyl, acridinyl, phenanthrolyl, dibenzofuranyl, and dibenzothiophenyl groups.

[0017] The alkoxy group may be an alkoxy group having 1 to 20 carbon atoms. Examples include, but are not limited to, a methoxy group, an ethoxy group, a propoxy group, etc.

[0018] A silyl group is a group in which a silicon atom has a substituent. The substituent may be a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. The substituted or unsubstituted alkyl group on the silicon atom may be a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms. The substituted or unsubstituted aryl group on the silicon atom may be a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. The silyl group may be a trialkylsilyl group or a triarylsilyl group. Specifically, examples include, but are not limited to, trimethylsilyl and triphenylsilyl groups.

[0019] Examples of substituents that alkyl groups, alkoxy groups, silyl groups, aryl groups, and heteroaryl groups may further include, but are not limited to, deuterium atoms; halogen atoms such as fluorine, chlorine, bromine, and iodine; alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl groups; alkoxy groups such as methoxy, ethoxy, and propoxy groups; amino groups such as dimethylamino, diethylamino, dibenzylamino, diphenylamino, and ditolylamino groups; aryloxy groups such as phenoxy; aromatic hydrocarbon groups such as phenyl and biphenyl; heteroaryl groups such as pyridyl and pyrrolyl groups; cyano, hydroxyl, and thiol groups.

[0020] ≪Features≫ The organic light-emitting element of the present invention has the following features: (1) The guest material is a compound with an orientation degree Pz value of 0.1 or less. (2) The first host material is a compound having two or more units AR. (3) The second host material is a compound represented by the following general formula [1] or general formula [2].

[0021] The details are explained below.

[0022] (1) The guest material is a compound with an orientation Pz value of 0.1 or less.

[0023] One of the features of the organic light-emitting element of this embodiment is that a compound with an orientation degree Pz value of 0.1 or less is used as the guest material for the light-emitting layer. Preferably, the guest material is a hydrocarbon compound. Here, the Pz value represents the magnitude of the component of the dipole moment related to the light emission of a molecule in the direction perpendicular to the substrate, when x and y are horizontal to the substrate in a Cartesian coordinate system of x, y, and z. That is, a small Pz value indicates that the transition dipole moment is oriented horizontally with respect to the substrate, i.e., a high degree of horizontal orientation. Preferably, the guest material is a compound with an orientation degree Pz value of 0.06 or less, and more preferably a compound with an orientation degree Pz value of 0.04 or less.

[0024] In addition to modes emitted outside the device, the light generated within the light-emitting layer of an organic light-emitting device includes modes that guide the substrate or organic thin film and modes that couple with surface plasmons of the electrodes. In these modes, the light cannot be extracted outside the device. However, light emitted from a transition dipole moment horizontally oriented on the substrate has a smaller proportion of these modes compared to random orientation or perpendicular orientation, making it easier to emit light outside the device. Therefore, by using a guest material with a small Pz value, it is possible to improve the luminescence efficiency.

[0025] Furthermore, as luminous efficiency improves, the amount of current required to achieve the same brightness decreases. Organic light-emitting elements degrade faster when the amount of current flowing through them increases. Therefore, improving luminous efficiency reduces the current flowing through the element, leading to improved durability.

[0026] (2) The first host material is a compound having two or more units AR.

[0027] Unit AR is defined as having sp carbon atoms as the constituent carbon atoms of the ring. ３It is a condensed polycyclic aromatic group with three or more rings that does not contain carbon. Unit AR is preferably a condensed polycyclic aromatic group with three to six rings, more preferably a condensed polycyclic aromatic group with three to five rings, and even more preferably a condensed polycyclic aromatic group with three to four rings. Therefore, the first host material having two or more units AR has a wide π-conjugated plane throughout the molecule. In an organic light-emitting device, charges are transported through the overlap of intermolecular orbits. Therefore, a material with a wide π-conjugated plane has the characteristic that orbits are likely to overlap between molecules and charge transport properties are excellent.

[0028] As described in (1), by using a guest material with a horizontally oriented transition dipole moment, the proportion of light extracted outside the device is improved. On the other hand, such a guest material has strong intermolecular interactions and is likely to aggregate, so there is a problem of inhibiting the charge transport of the host material and forming a charge accumulation in the light-emitting layer. A charge accumulation is a location where charges are locally present. When a charge accumulation is formed, quenching with excitons etc. occurs, causing the compound to be in a high-energy state, which may promote deterioration such as bond cleavage and lead to a decrease in the durability characteristics of the device.

[0029] It has been found that it is effective to use a host material having a wide π-conjugated plane and excellent charge transport properties. This is because a host material with a wide π-conjugated plane has higher compatibility with a highly oriented guest material and excellent charge transport properties compared to a host material with a small π-conjugated plane.

[0030] In addition, since the molecular weight is small and the sublimation property is high, the number of units AR is preferably two or more and five or less, more preferably two or more and three or less, and even more preferably two.

[0031] Unit AR may be a condensed polycyclic aromatic hydrocarbon group composed only of hydrocarbons, or may be a condensed polycyclic heteroaromatic group containing elements other than carbon in the ring structure. Unit AR is preferably a condensed polycyclic aromatic hydrocarbon group composed only of hydrocarbons. Also, unit AR may have a substituent, and the substituent may be an sp such as an alkyl group ３ It may also have a group containing carbon.

[0032] (3) The second host material is a compound represented by the following general formula [1] or general formula [2].

[0033]

[0034] [Ar １ Ar ２ In general formula [1] or general formula [2], Ar １ and Ar ２ These are different groups. Ar １ Ar is selected from substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups. １ It is preferable that the group be selected from substituted or unsubstituted aryl groups. ２ Ar is selected from a hydrogen atom, a deuterium atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. ２ Ar is preferably selected from a hydrogen atom, a substituted or unsubstituted aryl group, and more preferably from a substituted or unsubstituted aryl group. １ Ar ２ It is more preferably a substituted or unsubstituted aryl group having 6 to 25 carbon atoms. Specifically, Ar １ Ar ２ It is preferable that the group is selected from a phenyl group, a naphthyl group, a fluorenyl group, an anthracenyl group, and a 9,9'-spirobifluorenyl group. １ Ar ２ One of them is more preferably a fluorenyl group or a 9,9'-spirobifluorenyl group. Also, Ar １ Ar ２ The substituents that may be present may be substituted or unsubstituted alkyl groups, or substituted or unsubstituted aryl groups. Specifically, Ar １ Ar ２ The substituents that may be present are alkyl groups having 1 to 4 carbon atoms, and aryl groups having 6 to 14 carbon atoms.

[0035] [R １ ~R ８ In general formula [1] or general formula [2], R １ ~R８ R is independently selected from hydrogen atoms, deuterium atoms, halogen atoms, cyano groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted silyl groups, substituted or unsubstituted aryl groups consisting of two or fewer rings, and substituted or unsubstituted heteroaryl groups consisting of two or fewer rings. １ ~R ８ It is preferable that each of these be independently selected from a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, an aryl group consisting of two or fewer substituted or unsubstituted rings, and a heteroaryl group consisting of two or fewer substituted or unsubstituted rings; more preferably, each be independently selected from a hydrogen atom and a substituted or unsubstituted alkyl group; and even more preferably, it be a hydrogen atom.

[0036] The organic compounds represented by the above general formula [1] or general formula [2] have a pyrene skeleton or anthracene skeleton that can efficiently generate singlet excitons from a triplet excited state. Furthermore, Ar １ and Ar ２ Because they are different groups, Ar １ and Ar ２ Because it has an asymmetric molecular structure with respect to the pyrene or anthracene skeleton to which it is bonded, it is characterized by low crystallinity. The second host material is Ar １ and Ar ２ It is preferable that the molecular structure is asymmetrical with respect to the pyrene skeleton or anthracene skeleton to which it is bound.

[0037] The highly oriented guest material used in this embodiment has strong intermolecular interactions and is prone to aggregation. Aggregation makes the excitons on the guest material more susceptible to deactivation, leading to a decrease in the luminescence efficiency of the device. Therefore, a key feature of this invention is the use of a host material with low crystallinity that allows for uniform dispersion of the guest material.

[0038] <Comparison of Examples and Comparative Examples> Table 1 compares the light-emitting layer configuration and device characteristics of Inventions 1 to 2 and Comparative Examples 1 to 4. "Invention 1," "Invention 2," and "Comparative Example 1" to "Comparative Example 4" in Table 1 correspond to Example 1, Example 46, and Comparative Examples 1 to 4 in the Examples described later.

[0039] Furthermore, in Tables 1 to 9, 11, and 12, the method for fabricating the organic light-emitting element, the layer configuration, and the method for measuring the Pz value are as described in the examples below. The luminous efficiency ratio is 1000 cd / m². ２ The external quantum efficiency during display is measured and shown as a ratio when the efficiency of the element in Comparative Example 1 is set to 1.0. The element durability ratio is given by an initial brightness of 5000 cd / m². ２ A continuous operation test was conducted, and the brightness was measured after 100 hours. The results are shown as a ratio when the brightness of the element in Comparative Example 1 is set to 1.0.

[0040]

[0041] [Convention 1 to 2 and Comparative Example 1] These differ in the Pz value of the guest material. In Invention 1 to 2, as described in (1), the Pz value is 0.09, which makes it easier for light to be extracted outside the element, thereby improving the luminous efficiency and durability characteristics of the element.

[0042] [Invention 1 and Comparative Example 2] Even when using the same highly oriented guest material, the device characteristics differ depending on the molecular structure of the first host material. In Invention 1, as described in (2), having two AR units widens the π-conjugated plane and suppresses charge accumulation in the light-emitting layer, thereby improving the light-emitting efficiency and durability characteristics of the device.

[0043] [Invention 1 and Comparative Example 3] Even when using the same highly oriented guest material, the device characteristics differ depending on the molecular structure of the second host material. In Invention 1, as described in (3), the second host material has an asymmetric molecular structure, resulting in excellent dispersibility of the guest material, thus improving the luminescence efficiency and durability of the device.

[0044] [Invention 1 and Comparative Example 4] Even when using the same highly oriented guest material, the device characteristics differ depending on the molecular structure of the second host material. In Invention 1, as described in (3), the second host material has a pyrene structure, which allows for the efficient generation of singlet excitons from the triplet excited state, improving the luminescence efficiency and durability of the device.

[0045] As described above, the light-emitting layer configuration in this embodiment is characterized by comprising a guest material with a Pz value of 0.1 or less, a first host material having two or more units AR, and a second host material represented by the above general formula [1] or general formula [2]. By using a mixture of the first host material responsible for charge transport and the second host material which has excellent dispersibility with the guest material, it is possible to provide an organic light-emitting element with excellent luminous efficiency and durability when using a guest material with high orientation.

[0046] ≪Preferred Features≫ In the present invention, it is even more preferable to have the following features.

[0047] (4) The unit AR of the first host material is independently selected from pyrene residues, anthracene residues, triphenylene residues, phenanthrene residues, perylene residues, chrysene residues, tetracene residues, and fluorantene residues.

[0048] Pyrene residues, anthracene residues, triphenylene residues, phenanthrene residues, perylene residues, chrysene residues, tetracene residues, and fluorantene residues are preferred because they have a broad π-conjugated plane and excellent charge transport properties. They are also preferred because they consist of highly stable bonds, which reduces degradation during device operation. Here, "residue" refers to a group formed by removing a hydrogen atom at a predetermined position to create a bond.

[0049] Taking the compound Cz-Ph shown below as an example, the bond with low bond stability is the bond connecting the carbazole ring and the phenylene group (nitrogen-carbon bond). Bonds connecting carbon to carbon, such as in the compound Py-Ph, have higher bond stability. The calculation method used was b3-lyp / def2-SV(P).

[0050]

[0051] Table 2 compares the light-emitting layer configuration and device characteristics of Invention 3 and Invention 4. "Invention 3" and "Invention 4" in Table 2 refer to Examples 7 and 25 in the Examples described later.

[0052]

[0053] As shown in Table 2, Invention 3, which includes a triphenylene residue and an anthracene residue in the first host material, has a higher durability ratio than Invention 4, which includes a carbazole residue and anthracene residue in the first host material. Therefore, it is preferable that the first host material's unit AR is a condensed polycyclic aromatic hydrocarbon group such as a pyrene residue, anthracene residue, triphenylene residue, phenanthrene residue, perylene residue, chrysene residue, tetracene residue, or fluorantene residue.

[0054] (5) Of the two or more units AR of the first host material, at least two are the same group.

[0055] When the first host material has two or more identical AR units, molecular orbitals are more likely to overlap between molecules via these identical AR units, improving charge transport. As a result, charge accumulation is less likely to form in the light-emitting layer, improving the durability of the device. Therefore, it is preferable that at least two of the two or more AR units in the first host material are identical.

[0056] Table 3 compares the light-emitting layer configuration and device characteristics of Invention 3 and Invention 5. "Invention 5" in Table 3 is Example 8 in the Examples described later.

[0057]

[0058] As shown in Table 3, when comparing Invention 3 and Invention 5, Invention 5, which has two anthracene residues, has a higher durability ratio. Therefore, it is preferable that at least two of the two or more units AR of the first host material are the same group.

[0059] (6) When the same guest material is mixed with the host material at the same concentration, the photoluminescence quantum yield (PLQY) is higher with the second host material than with the first host material.

[0060] PLQY represents the photoexcitation quantum yield of the thin film on the substrate, and a high PLQY value suggests high dispersibility of the guest material. In this embodiment, it is preferable that the first host material is responsible for charge transport and the second host material is responsible for the dispersion of the guest material. Therefore, it is preferable that the second host material has a higher PLQY than the first host material.

[0061] Table 4 compares the light-emitting layer configuration and device characteristics of Invention 5 and Invention 6. "Invention 6" in Table 4 is Example 15 in the Examples described later.

[0062]

[0063] As shown in Table 4, when comparing Invention 5 and Invention 6, Invention 5, in which the PLQY of the second host material is higher than that of the first host material, has a higher durability ratio. This is because, in Invention 5, the charge transportability of the first host material is high, and the formation of charge accumulation is suppressed. Therefore, it is preferable that the PLQY of the second host material is higher than that of the first host material. The ratio of the PLQY of the first host material to that of the second host material (PLQY of the second host material / PLQY of the first host material) is preferably 1.01 or more and 1.21 or less, and more preferably 1.14 or more and 1.21 or less.

[0064] (7) The following formula (I) is satisfied: PAS-Ratio(first host material) > PAS-Ratio(second host material) (I) (In formula (I), PAS-Ratio is the molecular weight of the compound, with sp as the carbon atoms constituting the ring) ３ (This represents the ratio of molecular weights of three or more condensed polycyclic aromatic groups that do not contain carbon.)

[0065] PAS-Ratio represents the proportion of groups with broad π-conjugation relative to the entire molecule and is related to charge transport. In this embodiment, as described above, it is preferable that the first host material is responsible for charge transport and the second host material is responsible for the dispersion of the guest material. Therefore, it is preferable that the first host material has a higher PAS-Ratio than the second host material. Below is an example of calculating the PAS-Ratio for compound H1-1.

[0066]

[0067] Table 5 compares the light-emitting layer configuration and element characteristics of Invention 7 and Invention 8. "Invention 7" and "Invention 8" in Table 5 refer to Examples 9 and 10 in the Examples described later.

[0068]

[0069] As shown in Table 5, when comparing Invention 7 and Invention 8, Invention 7, in which the PAS-Ratio of the first host material is higher than that of the second host material, has higher luminous efficiency and durability ratio. Therefore, it is preferable that the PAS-Ratio of the first host material is higher than that of the second host material. The PAS-Ratio (first host material) is more preferably 0.53 or more and 0.79 or less, and more preferably 0.64 or more and 0.76 or less. Furthermore, the PAS-Ratio (second host material) is more preferably 0.27 or more and 0.74 or less, and more preferably 0.27 or more and 0.68 or less.

[0070] (8) The first host material and the second host material are hydrocarbon compounds.

[0071] As described in (4) above, in this embodiment, it is preferable that the compounds used do not have bonds with low bonding stability. Since the bonding stability around heteroatoms is low when heteroatoms are present, it is preferable that the first host material and the second host material are hydrocarbon compounds. Here, a hydrocarbon compound is a compound consisting only of carbon atoms and hydrogen atoms.

[0072] Table 6 compares the light-emitting layer configuration and device characteristics of Invention 5, Invention 9, and Invention 10. "Invention 9" and "Invention 10" in Table 6 are Examples 12 and 13 described later in the Examples section.

[0073]

[0074] As shown in Table 6, when comparing Invention 5 and Invention 9, Invention 5, in which the first host material is a hydrocarbon compound, has a higher durability ratio. Furthermore, when comparing Invention 5 and Invention 10, Invention 5, in which the second host material is a hydrocarbon compound, has a higher durability ratio. Therefore, it is preferable that the first host material and the second host material are hydrocarbon compounds.

[0075] (9) The first host material is a compound represented by the following general formula [3].

[0076]

[0077] [Ar] In general formula [3], Ar is a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group. Ar is preferably a substituted or unsubstituted arylene group, more preferably a substituted or unsubstituted arylene group having 6 to 25 carbon atoms, and even more preferably a substituted or unsubstituted arylene group having 6 to 18 carbon atoms. Specifically, divalent residues of benzene, biphenyl, terphenyl, naphthalene, fluorene, or 9,9'-spirobifluorene are preferred, and divalent residues of benzene, biphenyl, terphenyl, or naphthalene are even more preferred. Substituents that the arylene group may have may be substituted or unsubstituted aryl groups, or phenyl groups.

[0078] [R] In general formula [3], R is independently selected from a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. R is preferably independently selected from a substituted or unsubstituted alkyl group, more preferably independently selected from a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and may be a t-butyl group.

[0079] [l, m] In general formula [3], l and m each represent integers between 0 and 9, inclusive. It is preferable that l and m are 0 or 1, and more preferably 0.

[0080] Table 7 compares the light-emitting layer configuration and device characteristics of Invention 5 and Invention 7.

[0081]

[0082] As shown in Table 7, Invention 7 exhibits a higher durability ratio. This is because the first host material is a compound having two or more pyrene residues, which have strong intermolecular interactions and excellent charge transport properties. It is thought that the formation of charge accumulation is suppressed because the orbitals overlap easily between molecules and exhibit excellent charge transport properties. Therefore, the first host material is preferably a compound represented by general formula [3].

[0083] (10) The second host material is sp ３ It is a compound containing carbon.

[0084] As described above, the second host material is preferably excellent in dispersibility of the guest material. ３ Since carbon forms a tetrahedral structure, its presence reduces crystallinity. In other words, the second host material is sp ３ The inclusion of carbon is preferable because it improves the dispersibility of the guest material.

[0085] Table 8 compares the light-emitting layer configuration and device characteristics of Invention 5 and Invention 11. "Invention 11" in Table 8 is Example 26 in the Examples described later.

[0086]

[0087] As shown in Table 8, sp ３ The present invention 11, which contains carbon, has a high luminous efficiency ratio and durability ratio. Therefore, the first host material is sp ３ It is preferable that it contains carbon.

[0088] (11) The second host material is a compound represented by the following general formula [4].

[0089]

[0090] [R １１ ~R ２６ , R ３１ ~R ３９ In the general formula [4], R１１ ~R ２６ , R ３１ ~R ３９ Each of the following is independently selected: hydrogen atom, deuterium atom, halogen atom, cyano group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted silyl group, substituted or unsubstituted aryl group consisting of two or fewer rings, and substituted or unsubstituted heteroaryl group consisting of two or fewer rings. However, R １１ ~R １４ One of them bonds to the pyrene ring. １１ ~R ２６ , R ３１ ~R ３９ It is preferable that each is independently selected from a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, an aryl group consisting of two or fewer substituted or unsubstituted rings, and a heteroaryl group consisting of two or fewer substituted or unsubstituted rings; more preferably, it is independently selected from a hydrogen atom and a substituted or unsubstituted alkyl group; more preferably, it is independently selected from a hydrogen atom and a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms; and even more preferably, it is a hydrogen atom.

[0091] [n] In general formula [4], n represents an integer between 0 and 3, inclusive. It is preferable that n is an integer between 0 and 2, inclusive. When n is 2 or greater, R ３１ ~R ３４ This may differ for each repeating unit.

[0092] The compound represented by this general formula [4] has a bulky spiro structure and is characterized by low crystallinity. Therefore, it is preferable as a second host material because it has excellent dispersibility for guest materials.

[0093] Table 9 compares the light-emitting layer configuration and device characteristics of Invention 7 and Invention 12. "Invention 12" in Table 9 is Example 19 in the Examples described later.

[0094]

[0095] As shown in Table 9, the present invention 12, which uses a compound having a spiro structure as the second host material, exhibits a high luminescence efficiency ratio and durability ratio. Therefore, a compound having a spiro structure represented by general formula [4] is preferred as the second host material.

[0096] (12) The carbon atoms contained in the first host material are sp ２ It consists only of carbon.

[0097] As mentioned in (4) above, it is preferable that the compound used has high bonding stability. In Table 10, the carbon-carbon bond is shown as sp ２ Carbon and sp ３ The bond energies were compared for carbon. The calculation method used was b3-lyp / def2-SV(P).

[0098]

[0099] From the results in Table 10, sp ２ carbon-sp ２ It can be seen that carbon bonds have the highest bond energy.

[0100] Table 11 compares the light-emitting layer configuration and device characteristics of Invention 7 and Invention 13. "Invention 13" in Table 11 is Example 11 of the Examples described later.

[0101]

[0102] As shown in Table 11, the carbon atoms contained in the first host material are sp ２ The present invention 7, which consists only of carbon, has a high durability ratio. Therefore, the carbon atoms contained in the first host material are sp ２ It is preferable that it consists only of carbon.

[0103] (13) The following equation (II) is satisfied: Mass ratio of the first host material in the light-emitting layer [mass%] / Mass ratio of the second host material in the light-emitting layer [mass%] ≥ 1 (II)

[0104] Table 12 shows the relationship between the composition ratio of the first host material and the second host material and the element characteristics for the light-emitting layer configuration of this embodiment. For the light-emitting layer configuration, the guest material (OG-7) was fixed at 1 mass%, and the composition ratio of the first host material (H1-1) and the second host material (H2-1) was varied. "Invention 14" to "Invention 17" in Table 12 are Examples 16 to 19 in the embodiments described later.

[0105]

[0106] The results in Table 12 show that as the proportion of the first host material increases, the luminous efficiency remains unchanged, but the durability of the device improves. This is because even a small amount of the second host material can effectively disperse the guest material. Therefore, it is preferable that the mass ratio of the first host in the light-emitting layer is greater than the mass ratio of the second host material, that is, it is preferable that it satisfies the following equation (III), more preferably the following equation (IV), even more preferably the following equation (V), and even more preferably the following equation (VI).

[0107] Mass ratio of first host material in the light-emitting layer [mass%] / Mass ratio of second host material in the light-emitting layer [mass%] > 1 (III) Mass ratio of first host material in the light-emitting layer [mass%] / Mass ratio of second host material in the light-emitting layer [mass%] ≥ 1.02 (IV) Mass ratio of first host material in the light-emitting layer [mass%] / Mass ratio of second host material in the light-emitting layer [mass%] ≥ 5.60 (V) Mass ratio of first host material in the light-emitting layer [mass%] / Mass ratio of second host material in the light-emitting layer [mass%] ≥ 8.90 (VI)

[0108] ≪Specific Examples of Guest Materials, First Host Materials, and Second Host Materials≫ Below are specific examples of guest materials, first host materials, and second host materials.

[0109] <Guest Material> In this embodiment, the guest material is a compound with a horizontal orientation degree Pz value of 0.1 or less, preferably a hydrocarbon compound. Specific examples of guest materials are listed below, but are not limited to these.

[0110]

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117] <First host material> In this embodiment, the first host material is a unit AR (with sp carbon atoms constituting the ring). ３ The compound has two or more condensed polycyclic aromatic groups (with three or more rings but no carbon atoms). The unit AR is preferably independently selected from pyrene residues, anthracene residues, triphenylene residues, phenanthrene residues, perylene residues, chrysene residues, and tetracene residues. Furthermore, it is preferable that at least two of the unit ARs are the same group. The first host material is preferably a hydrocarbon compound, and more preferably a compound represented by general formula [3]. Also, the carbon atoms contained in the first host material are sp ２ It is preferable that the material consists solely of carbon. Specific examples of preferred first host materials are shown below, but the material is not limited to these.

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125] <Second Host Material> In this embodiment, the second host material is a compound represented by general formula [1] or general formula [2], and is preferably a hydrocarbon compound. Also, the second host material is sp ３ The compound is preferably a carbon-containing compound, and more preferably a compound represented by general formula [4]. Specific examples of preferred second host materials are shown below, but are not limited to these.

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132] ≪Configuration of Organic Light-Emitting Device≫ The organic light-emitting device of this embodiment has a pair of electrodes and an organic compound layer disposed between the pair of electrodes. Here, the organic compound layer has at least a light-emitting layer, and if the organic compound layer is a laminate consisting of multiple layers, in addition to the light-emitting layer, it may also have a hole injection layer, a hole transport layer, an electron blocking layer, a hole / exciton blocking layer, an electron transport layer, an electron injection layer, etc. Furthermore, the light-emitting layer may be a single layer or a laminate consisting of multiple layers.

[0133] In the organic light-emitting device of this embodiment, at least one layer of the organic compound layer contains the guest material, the first host material, and the second host material. The layer containing these guest material, first host material, and second host material is preferably a light-emitting layer. If it is a light-emitting layer, the first host material is preferably the host and the second host material is preferably the assist.

[0134] The host is the compound with the largest mass ratio among the compounds that make up the luminescent layer. The guest is the compound with a smaller mass ratio than the host among the compounds that make up the luminescent layer, and is responsible for the primary luminescence. The assist is the compound with a smaller mass ratio than the host among the compounds that make up the luminescent layer, and is greater than or equal to the guest. In other words, the mass ratio is host > assist ≥ guest.

[0135] The light-emitting layer according to this embodiment consists of at least three compounds. The concentration of the host is preferably 50% by mass or more and 99% by mass or less, and more preferably 50% by mass or more and 98% by mass or less, relative to the entire light-emitting layer. The concentration of the guest is preferably 0.1% by mass or more and 20% by mass or less, relative to the entire light-emitting layer, and more preferably 1% by mass or more and 10% by mass or less, from the viewpoint of preventing concentration quenching. Furthermore, the concentration of the assist is preferably greater than 0.5% by mass and 49.09% by mass or less, more preferably 2% by mass or more and 49.09% by mass or less, and more preferably 5% by mass or more and 49.09% by mass or less, relative to the entire light-emitting layer.

[0136] The guest material may be uniformly distributed throughout the entire layer where the host matrix is ​​located, or it may be distributed in a concentration gradient. Alternatively, the guest material may be partially distributed in specific regions within the layer, so that the luminescent layer has regions containing only the host and no guest material.

[0137] The light-emitting layer may be a single layer or a multi-layer, and it is also possible to mix colors by including light-emitting materials having other emission colors. A multi-layer means a state in which two or more light-emitting layers are stacked. In this case, the emission color of the organic light-emitting element is not particularly limited. More specifically, it may be white or an intermediate color. In the case of white, for example, if the emission color of one light-emitting layer is blue, another light-emitting layer will emit a different color from blue, namely green or red. Furthermore, a third light-emitting layer that emits blue light and a charge generation layer may be provided between the light-emitting layer or stacked light-emitting layer in this embodiment and the first or second electrode. The charge generation layer exhibits the function of a tandem element, where electrons generated from the charge generation layer and holes injected from the first electrode recombine to generate excitons, and holes generated from the charge generation layer and electrons injected from the second electrode recombine to form excitons. As a result, the internal quantum efficiency is doubled. In this case, the organic light-emitting element of this embodiment can be applied to one side of the tandem element as a blue light-emitting layer as the complementary color to yellow emission. Therefore, by using the blue light-emitting layer made up of the light-emitting layer in this embodiment and arranging it in a tandem element configuration with a yellow light-emitting layer, a white light-emitting element can be provided. Furthermore, film formation can be performed by vapor deposition or coating.

[0138] ) (1) Anode / Emitting layer / Cathode (2) Anode / Hole transport layer / Emitting layer / Electron transport layer / Cathode (3) Anode / Hole transport layer / Emitting layer / Electron transport layer / Electron injection layer / Cathode (4) Anode / Hole injection layer / Hole transport layer / Emitting layer / Electron transport layer / Cathode (5) Anode / Hole injection layer / Hole transport layer / Emitting layer / Electron transport layer / Electron injection layer / Cathode (6) Anode / Hole transport layer / Electron blocking layer / Emitting layer / Hole blocking layer / Electron transport layer / Cathode

[0139] However, these examples of element configurations are merely very basic configurations and are not limited to them. For example, a variety of layer configurations can be adopted, such as providing an insulating layer, adhesive layer, or interference layer at the interface between the electrode and the organic compound layer, having an electron transport layer or hole transport layer composed of two layers with different ionization potentials, or having a light-emitting layer composed of two layers of different light-emitting materials.

[0140] In the device configurations shown in (1) to (6) above, configuration (6) is preferred because it has both an electron blocking layer and a hole blocking layer. In other words, in configuration (6) which has both an electron blocking layer and a hole blocking layer, both hole and electron carriers can be reliably confined within the light-emitting layer, resulting in an organic light-emitting element with no carrier leakage and high light-emitting efficiency.

[0141] The method of extracting light from the light-emitting layer (device configuration) can be either a so-called bottom emission method, where light is extracted from the electrode on the substrate side, or a so-called top emission method, where light is extracted from the opposite side of the substrate. A double-sided extraction method, where light is extracted from both the substrate side and the opposite side of the substrate, can also be employed.

[0142] <Other Compounds> The organic compounds of the guest material, first host material, and second host material according to this embodiment can be used as constituent materials for organic compound layers other than the light-emitting layer constituting the organic light-emitting element of this embodiment. Specifically, they may be used as constituent materials for electron transport layers, electron injection layers, hole transport layers, hole injection layers, hole blocking layers, etc. In this case, the light-emitting color of the organic light-emitting element is not particularly limited. More specifically, it may be white or an intermediate color.

[0143] In addition to the organic compounds according to this embodiment, conventionally known low-molecular-weight and high-molecular-weight hole-injecting or hole-transporting compounds, host compounds, luminescent compounds, electron-injecting or electron-transporting compounds, etc., can be used together as needed. Examples of these compounds are listed below.

[0144] As hole-implantation transport materials, materials with high hole mobility are preferred to facilitate hole injection from the anode and to transport the injected holes to the light-emitting layer. Furthermore, materials with a high glass transition temperature are preferred to reduce film quality degradation such as crystallization in organic light-emitting devices. Examples of low-molecular-weight and high-molecular-weight materials with hole-implantation transport properties include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinylcarbazole), poly(thiophene), and other conductive polymers. Moreover, the above-mentioned hole-implantation transport materials are also suitably used in electron-blocking layers. Specific examples of compounds used as hole-implantation transport materials are shown below, but are not limited to these.

[0145]

[0146] Among the hole transport materials listed, HT16 to HT18 can reduce the driving voltage when used in the layer in contact with the anode. HT16 is widely used in organic light-emitting devices. HT2, HT3, HT4, HT5, HT6, HT10, and HT12 may be used in the organic compound layer adjacent to HT16. Furthermore, multiple materials may be used in a single organic compound layer.

[0147] Luminescent materials primarily involved in light emission include fused ring compounds (e.g., fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, rubrene, etc.), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organoaluminum complexes such as tris(8-quinolinolate)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives such as poly(phenylenevinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives. Specific examples of compounds used as luminescent materials are shown below, but are not limited to these.

[0148]

[0149]

[0150] When the luminescent material is a hydrocarbon compound, it is preferable because it can reduce the decrease in luminescence efficiency due to excyplex formation and the decrease in color purity due to changes in the emission spectrum of the luminescent material caused by excyplex formation. A hydrocarbon compound is a compound composed only of carbon and hydrogen, and among the example compounds above, these are BD7, BD8, GD5 to GD9, and RD1.

[0151] When the light-emitting material is a condensed polycyclic material containing a five-membered ring, it is preferable because its ionization potential is high, making it less susceptible to oxidation and resulting in a highly durable device with a long lifespan. Among the example compounds listed above, BD7, BD8, GD5 to GD9, and RD1 are preferred.

[0152] Examples of luminescent layer hosts or luminescence assist materials included in the luminescent layer include aromatic hydrocarbon compounds or their derivatives, as well as carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes such as tris(8-quinolinolate)aluminum, and organoberylium complexes. Specific examples of compounds used as luminescent layer hosts or luminescence assist materials are shown below, but are not limited to these.

[0153]

[0154] When the host material is a hydrocarbon compound, the compound of this embodiment is preferable because it can easily trap electrons and holes, thus greatly improving efficiency. A hydrocarbon compound is a compound composed only of carbon and hydrogen, and among the example compounds above, these are EM1 to EM26. As for the host material, it is more preferable from the viewpoint of stability if the single bond connecting the aryl group unit in its structure does not have a carbon-heteroatom bond.

[0155] As electron-transporting materials, any material capable of transporting electrons injected from the cathode to the light-emitting layer can be arbitrarily selected, taking into consideration the balance with the hole mobility of the hole-transporting material. Examples of materials with electron-transporting properties include oxadiazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organoaluminum complexes, and fused ring compounds (e.g., fluorene derivatives, naphthalene derivatives, chrysene derivatives, anthracene derivatives, etc.). Furthermore, the above electron-transporting materials are also suitably used in the hole-blocking layer. Specific examples of compounds used as electron-transporting materials are shown below, but are of course not limited to these.

[0156]

[0157] Electron injection materials can be arbitrarily selected from those that allow for easy electron injection from the cathode, taking into consideration the balance with hole injection properties. Organic compounds include n-type dopants and reducing dopants. Examples include alkali metal compounds such as lithium fluoride, lithium complexes such as lithium quinolinol, benzimidazolidene derivatives, imidazolidene derivatives, fluvalene derivatives, and acridine derivatives. They can also be used in combination with the above-mentioned electron transport materials.

[0158] <Other configurations of organic light-emitting elements> An organic light-emitting element is provided by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, a color filter, a microlens, etc., may be provided on the cathode. If a color filter is provided, a planarization layer may be provided between it and the protective layer. The planarization layer can be made of acrylic resin or the like. The same applies when a planarization layer is provided between the color filter and the microlens.

[0159] [Substrate] Examples of substrates include quartz, glass, silicon wafers, resins, and metals. Switching elements such as transistors and wiring may be provided on the substrate, and an insulating layer may be provided on top of them. The insulating layer can be made of any material that allows for the formation of contact holes so that wiring can be formed between it and the first electrode, and that ensures insulation from wiring that is not connected. For example, resins such as polyimide, silicon oxide, and silicon nitride can be used.

[0160] [Electrodes] A pair of electrodes can be used. The pair of electrodes may be an anode and a cathode. When an electric field is applied in the direction in which the organic light-emitting element emits light, the electrode with the higher potential is the anode, and the other is the cathode. Alternatively, the electrode that supplies holes to the light-emitting layer can be the anode, and the electrode that supplies electrons can be the cathode.

[0161] For the anode, materials with the largest possible work function are preferable. For example, elemental metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten, or mixtures containing these, or alloys combining them, as well as metal oxides such as tin oxide, zinc oxide, indium oxide, tin-indium oxide (ITO), and zinc-indium oxide can be used. Conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used.

[0162] These electrode materials may be used individually or in combination of two or more. Furthermore, the anode may consist of a single layer or multiple layers.

[0163] When used as a reflective electrode, materials such as chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or laminates thereof can be used. It is also possible to use the above materials as a reflective film without serving as an electrode. Furthermore, when used as a transparent electrode, oxide transparent conductive layers such as indium tin oxide (ITO) or indium zinc oxide can be used, but are not limited to these. Photolithography can be used to form the electrodes.

[0164] On the other hand, materials with a small work function are preferred for the cathode. Examples include alkali metals such as lithium, alkaline earth metals such as calcium, and elemental metals or mixtures containing these, such as aluminum, titanium, manganese, silver, lead, and chromium. Alternatively, alloys combining these elemental metals can also be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver can be used. Metal oxides such as indium tin oxide (ITO) can also be used. These electrode materials may be used individually or in combination of two or more. The cathode may also be a single-layer or multi-layer structure. Among these, silver is preferred, and a silver alloy is even more preferred to reduce silver aggregation. The alloy ratio is not important as long as silver aggregation is reduced. For example, the ratio of silver to other metals may be 1:1, 3:1, etc.

[0165] The cathode may be a top-emission element using an oxide conductive layer such as ITO, or a bottom-emission element using a reflective electrode such as aluminum (Al), and is not particularly limited. The method for forming the cathode is not particularly limited, but using DC and AC sputtering methods is more preferable because it provides good film coverage and makes it easier to reduce resistance.

[0166] [Pixel Separation Tank] The pixel separation layer is formed from a silicon nitride (SiN), silicon oxynitride (SiON), or silicon oxide (SiO) film, which is formed using chemical vapor deposition (CVD). To increase the in-plane resistance of the organic compound layer, it is preferable that the thickness of the organic compound layer, especially the hole transport layer, be thinly deposited on the sidewalls of the pixel separation layer. Specifically, by increasing the taper angle of the sidewalls of the pixel separation layer and the thickness of the pixel separation layer, the thickness of the sidewalls can be thinned by increasing vignetting during deposition.

[0167] On the other hand, it is preferable to adjust the taper angle of the sidewalls of the pixel isolation layer and the thickness of the pixel isolation layer to such an extent that no voids are formed in the protective layer formed on top of it. Since no voids are formed in the protective layer, the occurrence of defects in the protective layer can be reduced. Since the occurrence of defects in the protective layer is reduced, reliability degradation such as the occurrence of dark spots and poor conductivity of the second electrode can be reduced.

[0168] According to this embodiment, charge leakage to adjacent pixels can be effectively suppressed even if the taper angle of the sidewall of the pixel isolation layer is not steep. As a result of this study, it was found that sufficient reduction is possible when the taper angle is in the range of 60 degrees to 90 degrees. The thickness of the pixel isolation layer is preferably between 10 nm and 150 nm. Furthermore, a similar effect can be obtained even if the device is composed only of pixel electrodes without a pixel isolation layer. However, in this case, it is preferable that the thickness of the pixel electrode be less than half that of the organic layer, or that the ends of the pixel electrodes have a forward taper of less than 60°, as this can reduce short circuits in the organic light-emitting element.

[0169] [Organic Compound Layer] The organic compound layer may be formed as a single layer or as multiple layers. If there are multiple layers, they may be called a hole injection layer, a hole transport layer, an electron blocking layer, an emissive layer, a hole blocking layer, an electron transport layer, or an electron injection layer, depending on their function. The organic compound layer is mainly composed of organic compounds, but may also contain inorganic atoms and inorganic compounds. For example, it may contain copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, zinc, etc. The organic compound layer may be placed between the first electrode and the second electrode, or it may be placed in contact with the first electrode and the second electrode.

[0170] When there are multiple light-emitting layers, a charge generation section may be provided between the first and second light-emitting layers. The charge generation section may contain an organic compound with a minimum unoccupied molecular orbital energy (LUMO) of -5.0 eV or less. The same applies when the charge generation section is provided between the second and third light-emitting layers.

[0171] The organic compound layer (hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) constituting the organic light-emitting element according to one embodiment of the present invention is formed by the method shown below.

[0172] The organic compound layer constituting the organic light-emitting element according to one embodiment of the present invention can be formed using a dry process such as vacuum deposition, ionization deposition, sputtering, or plasma deposition. Alternatively, instead of a dry process, a wet process can be used in which the layer is formed by dissolving the compound in a suitable solvent and applying a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method, etc.).

[0173] When layers are formed using methods such as vacuum deposition or solution coating, crystallization is less likely to occur, resulting in excellent stability over time. Furthermore, when forming films using coating methods, it is possible to combine the film with an appropriate binder resin.

[0174] Examples of the binder resins mentioned above include, but are not limited to, polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

[0175] Furthermore, these binder resins may be used individually as homopolymers or copolymers, or as a mixture of two or more types. Additionally, known additives such as plasticizers, antioxidants, and UV absorbers may be used in combination as needed.

[0176] [Protective Layer] A protective layer may be provided on the second electrode. For example, by bonding glass with a desiccant to the second electrode, the intrusion of water and other substances into the organic compound layer can be reduced, thereby reducing the occurrence of display defects. In another embodiment, a passivation film such as silicon nitride may be provided on the cathode to reduce the intrusion of water and other substances into the organic compound layer. For example, after forming the cathode, the material may be transported to another chamber without breaking the vacuum, and a silicon nitride film with a thickness of 2 μm may be formed by CVD to serve as a protective layer. A protective layer may also be provided using atomic deposition (ALD) after the film formation by CVD. The material of the film formed by ALD is not limited, but may be silicon nitride, silicon oxide, aluminum oxide, etc. Silicon nitride may be further formed by CVD on the film formed by ALD. The film formed by ALD may have a thinner film thickness than the film formed by CVD. Specifically, it may be 50% or less, or even 10% or less.

[0177] [Color Filter] A color filter may be provided on top of the protective layer. For example, a color filter that takes into account the size of the organic light-emitting element may be provided on a separate substrate and bonded to the substrate on which the organic light-emitting element is provided, or a color filter may be patterned on the protective layer as described above using photolithography technology. The color filter may be made of polymer.

[0178] [Planarizing Layer] A planarizing layer may be provided between the color filter and the protective layer. The planarizing layer is provided for the purpose of reducing the unevenness of the layer below. It may also be called a material resin layer without limiting its purpose. The planarizing layer may be composed of an organic compound, and may be low molecular weight or high molecular weight, but high molecular weight is preferred.

[0179] The planarization layer may be provided above or below the color filter, and its constituent materials may be the same or different. Specifically, examples include polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, urea resin, etc.

[0180] [Microlenses] Organic light-emitting elements may have optical components such as microlenses on their light-emitting side. Microlenses may be made of acrylic resin, epoxy resin, etc. Microlenses may be used to increase the amount of light extracted from the organic light-emitting element or to control the direction of the extracted light. Microlenses may have a hemispherical shape. If they have a hemispherical shape, among the tangents tangent to the hemisphere, there is a tangent parallel to the insulating layer, and the point of contact between that tangent and the hemisphere is the vertex of the microlens. The vertex of the microlens can be similarly determined in any cross-sectional view. That is, among the tangents tangent to the semicircle of the microlens in the cross-sectional view, there is a tangent parallel to the insulating layer, and the point of contact between that tangent and the semicircle is the vertex of the microlens.

[0181] Furthermore, the midpoint of a microlens can also be defined. In the cross-section of a microlens, a line segment can be imagined from the point where one arc ends to the point where another arc ends, and the midpoint of this line segment can be called the midpoint of the microlens. The cross-section used to determine the vertices and midpoints may be a cross-section perpendicular to the insulating layer.

[0182] A microlens has a first surface with a convex portion and a second surface opposite to the first surface. It is preferable that the second surface is positioned closer to the functional layer than the first surface. To adopt such a configuration, it is necessary to form a microlens on a light-emitting element. If the functional layer is an organic layer, it is preferable to avoid processes that involve high temperatures during the manufacturing process. Furthermore, when adopting a configuration in which the second surface is positioned closer to the functional layer than the first surface, it is preferable that the glass transition temperatures of all organic compounds constituting the organic layer are 100°C or higher, and more preferably 130°C or higher.

[0183] [Opposite Substrate] An opposite substrate may be provided on the planarization layer. The opposite substrate is called an opposite substrate because it is provided in a position corresponding to the aforementioned substrate. The constituent material of the opposite substrate may be the same as that of the aforementioned substrate. The opposite substrate may be the second substrate if the aforementioned substrate is the first substrate.

[0184] [Pixel Circuit] The light-emitting device may have a pixel circuit connected to a light-emitting element. The pixel circuit may be an active-matrix type that independently controls the light emission of a first light-emitting element and a second light-emitting element. The active-matrix type circuit may be voltage-programmed or current-programmed. The drive circuit has a pixel circuit for each pixel. The pixel circuit may include a light-emitting element, a transistor that controls the light emission brightness of the light-emitting element, a transistor that controls the light emission timing, a capacitor that holds the gate voltage of the transistor that controls the light emission brightness, and a transistor for connecting to GND without going through the light-emitting element.

[0185] The light-emitting device has a display area and a peripheral area arranged around the display area. The display area has a pixel circuit, and the peripheral area has a display control circuit. The mobility of the transistors constituting the pixel circuit may be smaller than the mobility of the transistors constituting the display control circuit.

[0186] The slope of the current-voltage characteristics of the transistors constituting the pixel circuit may be smaller than the slope of the current-voltage characteristics of the transistors constituting the display control circuit. The slope of the current-voltage characteristics can be measured using the so-called Vg-Ig characteristic.

[0187] The transistors that make up the pixel circuit are transistors connected to light-emitting elements, such as the first light-emitting element.

[0188] [Pixels] The organic light-emitting device has a plurality of pixels. Each pixel has sub-pixels that emit different colors from the others. The sub-pixels may each have, for example, RGB emission colors.

[0189] A pixel emits light in a region also called the pixel aperture. This region is the same as the first region. The pixel aperture may be 15 μm or less, or 5 μm or more. More specifically, it may be 11 μm, 9.5 μm, 7.4 μm, 6.4 μm, etc.

[0190] The distance between subpixels may be 10 μm or less, specifically 8 μm, 7.4 μm, or 6.4 μm.

[0191] Pixels can take on known arrangements in a plan view. For example, they may be in a stripe arrangement, delta arrangement, pentile arrangement, or Bayer arrangement. The shape of subpixels in a plan view may be any known shape. For example, rectangles, rhombuses, hexagons, etc. Of course, even if it is not a precise shape, if it is close to a rectangle, it is included in the category of rectangles. The shape of subpixels and the pixel arrangement can be used in combination.

[0192] <<Applications of the Organic Light-Emitting Device According to One Embodiment of a Certain Invention>> The organic light-emitting device according to one embodiment of a certain invention can be used as a component of a display device or lighting device. Other applications include exposure light sources for electrophotographic image forming apparatuses, backlights for liquid crystal display devices, and light-emitting devices with a color filter in a white light source.

[0193] The display device may also be an image information processing device that has an image input unit for receiving image information from an area CCD, linear CCD, memory card, etc., an information processing unit for processing the input information, and displays the input image on the display unit.

[0194] Furthermore, the display unit of the imaging device or inkjet printer may have a touch panel function. The driving method for this touch panel function may be infrared, capacitive, resistive, or electromagnetic induction, and is not particularly limited. The display device may also be used as the display unit of a multifunction printer.

[0195] Next, a display device according to this embodiment will be described with reference to the drawings. Figures 1A and 1B are schematic cross-sectional views showing an example of a display device having an organic light-emitting element and a transistor connected to the organic light-emitting element. The transistor is an example of an active element. The transistor may also be a thin-film transistor (TFT).

[0196] Figure 1A is a schematic cross-sectional view of an example of a pixel, which is a component of the display device according to this embodiment. The pixel has sub-pixels 10. The sub-pixels are divided into 10R, 10G, and 10B based on their light emission. The emitted colors may be distinguished by the wavelength emitted from the light-emitting layer, or the light emitted from the sub-pixel may be selectively transmitted or color-converted by a color filter or the like. Each sub-pixel 10 has a reflective electrode which is a first electrode 2 on an interlayer insulating layer 1, an insulating layer 3 covering the end of the first electrode 2, an organic compound layer 4 covering the first electrode 2 and the insulating layer 3, a transparent electrode which is a second electrode 5, a protective layer 6, and a color filter 7.

[0197] The interlayer insulating layer 1 may have transistors and capacitive elements placed in the layer below or inside it. The transistor and the first electrode 2 may be electrically connected via a contact hole or the like (not shown).

[0198] The insulating layer 3 is also called a bank or pixel isolation layer. It covers the end of the first electrode 2 and is arranged to surround the first electrode 2. The portion not covered by the insulating layer 3 is in contact with the organic compound layer 4 and becomes the light-emitting region.

[0199] The organic compound layer 4 includes a hole injection layer 41, a hole transport layer 42, a light-emitting layer 43, a hole blocking layer 44, and an electron transport layer 45.

[0200] The second electrode 5 may be a transparent electrode, a reflective electrode, or a semi-transparent electrode.

[0201] The protective layer 6 reduces the penetration of moisture into the organic compound layer 4. Although the protective layer 6 is shown as a single layer, it may consist of multiple layers. Each layer may contain an inorganic compound layer and an organic compound layer.

[0202] The color filter 7 is classified into 7R, 7G, and 7B according to its color. The color filter 7 may be formed on a planarization film (not shown). The color filter 7 may also have a resin protective layer (not shown). Alternatively, the color filter 7 may be formed on a protective layer 6, or it may be bonded to an opposing substrate such as a glass substrate after being placed on it.

[0203] The display device 100 in Figure 1B includes an organic light-emitting element 26 and a TFT 18, which is an example of a transistor. A substrate 11 made of glass, silicon, or the like is provided, with an insulating layer 12 on top of it. An active element such as the TFT 18 is placed on the insulating layer 12, and the active element has a gate electrode 13, a gate insulating film 14, and a semiconductor layer 15. The TFT 18 has a drain electrode 16 and a source electrode 17. An insulating film 19 is provided on top of the TFT 18. The anode 21 and the source electrode 17 constituting the organic light-emitting element 26 are connected via a contact hole 20 provided in the insulating film 19.

[0204] Furthermore, the method of electrical connection between the electrodes (anode 21, cathode 23) included in the organic light-emitting element 26 and the electrodes (source electrode 17, drain electrode 16) included in the TFT 18 is not limited to the configuration shown in Figure 1B. In other words, it is sufficient that either the anode 21 or the cathode 23 is electrically connected to either the source electrode 17 or the drain electrode 16 of the TFT 18.

[0205] In the display device 100 shown in Figure 1B, the organic compound layer 22 is depicted as a single layer, but the organic compound layer 22 may consist of multiple layers. A first protective layer 24 and a second protective layer 25 are provided on the cathode 23 to reduce the degradation of the organic light-emitting element 26.

[0206] In the display device 100 shown in Figure 1B, a transistor is used as the switching element, but other switching elements such as MIM elements may be used instead.

[0207] Furthermore, the transistor used in the display device 100 in Figure 1B is not limited to a thin-film transistor having an active layer on the insulating surface of the substrate, but may also be a transistor using a single-crystal silicon wafer. Examples of the active layer include non-single-crystal silicon such as single-crystal silicon, amorphous silicon, and microcrystalline silicon, and non-single-crystal oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide. Thin-film transistors are also called TFT elements.

[0208] The transistors included in the display device 100 in Figure 1B may be formed within a substrate such as a Si substrate. Here, "formed within a substrate" means that the transistors are manufactured by processing the substrate itself, such as a Si substrate. In other words, having transistors within a substrate can be seen as the substrate and transistors being formed as a single unit.

[0209] The organic light-emitting element according to this embodiment has its luminescence controlled by a TFT, which is an example of a switching element, and by providing multiple organic light-emitting elements on the surface, an image can be displayed according to the luminescence of each element. The switching element according to this embodiment is not limited to a TFT, but may also be a transistor made of low-temperature polysilicon, or an active matrix driver formed on a substrate such as a Si substrate. "On the substrate" can also mean "within the substrate." Whether to provide a transistor within the substrate or to use a TFT is selected depending on the size of the display area; for example, if the size is about 0.5 inches, it is preferable to provide the organic light-emitting element on a Si substrate.

[0210] Figure 2 is a schematic diagram showing an example of a display device according to this embodiment. The display device 1000 may have a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. Flexible printed circuits FPCs 1002 and 1004 are connected to the touch panel 1003 and the display panel 1005. Transistors are printed on the circuit board 1007. The battery 1008 does not need to be provided if the display device is not a portable device, or it may be provided in a different location even if it is a portable device.

[0211] The display device according to this embodiment may have a color filter having red, green, and blue colors. The color filter may have the red, green, and blue colors arranged in a delta array.

[0212] The display device according to this embodiment may be used in the display unit of a mobile terminal. In that case, it may have both display and operation functions. Examples of mobile terminals include smartphones and other mobile phones, tablets, and head-mounted displays.

[0213] The display device according to this embodiment may be used in the display unit of an imaging device having an optical unit with multiple lenses and an image sensor that receives light that has passed through the optical unit. The imaging device may have a display unit that displays information acquired by the image sensor. Furthermore, the display unit may be a display unit exposed to the outside of the imaging device or a display unit located inside the viewfinder. The imaging device may be a digital camera or a digital video camera.

[0214] Figure 3A is a schematic diagram showing an example of an imaging device according to this embodiment. The imaging device 1100 may include a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 may have a display device according to this embodiment. In that case, the display device may display not only the image to be captured, but also environmental information, imaging instructions, etc. Environmental information may include the intensity of ambient light, the direction of ambient light, the speed at which the subject is moving, the possibility of the subject being obscured by an obstacle, etc.

[0215] Since the optimal timing for imaging is very short, it is best to display the information as quickly as possible. Therefore, it is preferable to use a display device using the organic light-emitting element of the present invention, because organic light-emitting elements have a fast response speed. Display devices using organic light-emitting elements can be used more suitably than liquid crystal display devices, which require a fast display speed.

[0216] The imaging device 1100 has an optical section (not shown). The optical section has multiple lenses that form an image on the image sensor housed in the housing 1104. The focus can be adjusted by adjusting the relative positions of the multiple lenses. This operation can also be performed automatically. The imaging device may also be called a photoelectric converter. The photoelectric converter does not capture images sequentially, but may include imaging methods such as detecting the difference from the previous image or extracting from an image that is always being recorded.

[0217] Figure 3B is a schematic diagram showing an example of an electronic device according to this embodiment. The electronic device 1200 has a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may have a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch panel type response unit. The operation unit may also be a biometric recognition unit that recognizes fingerprints to unlock or otherwise perform actions. An electronic device having a communication unit can also be called a communication device. The electronic device may further have a camera function by including a lens and an image sensor. Images captured by the camera function are displayed on the display unit. Examples of electronic devices include smartphones and laptop computers.

[0218] Figures 4A and 4B are schematic diagrams showing an example of a display device according to this embodiment. Figure 4A is a display device such as a television monitor or a PC monitor. The display device 1300 has a frame 1301 and a display unit 1302. The display unit 1302 may use the light-emitting device according to this embodiment.

[0219] It has a frame 1301 and a base 1303 that supports the display unit 1302. The base 1303 is not limited to the form shown in Figure 4A. The bottom edge of the frame 1301 may also serve as the base. In addition, the frame 1301 and the display unit 1302 may be curved. The radius of curvature may be between 5000 mm and 6000 mm.

[0220] Figure 4B is a schematic diagram showing another example of a display device according to this embodiment. The display device 1310 in Figure 4B is configured to be foldable and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 may have light-emitting devices according to this embodiment. The first display unit 1311 and the second display unit 1312 may be a single display device without seams. The first display unit 1311 and the second display unit 1312 can be separated at a bending point. The first display unit 1311 and the second display unit 1312 may each display different images, or the first and second display units may together display a single image.

[0221] Figure 5 is a schematic diagram showing an example of a lighting device according to this embodiment. The lighting device 1400 may include a housing 1401, a light source 1402, a circuit board 1403, an optical film 1404, and a light diffusion section 1405. The light source 1402 may have an organic light-emitting element according to this embodiment. The optical film 1404 may be a film that improves the color rendering of the light source. The light diffusion section 1405 can effectively diffuse the light from the light source 1402, such as for lighting up, and deliver light over a wide area. The optical film 1404 and the light diffusion section 1405 may be provided on the light-emitting side of the lighting. A cover may be provided on the outermost part as needed.

[0222] The lighting device is, for example, a device for illuminating a room. The lighting device may emit white light, daylight white light, or any other color from blue to red. It may have a dimming circuit to adjust the brightness of these lights. The lighting device may have the organic light-emitting element of the present invention and a power supply circuit connected thereto. The power supply circuit is a circuit that converts AC voltage to DC voltage. White light has a color temperature of 4200K, and daylight white light has a color temperature of 5000K. The lighting device may have a color filter.

[0223] Furthermore, the lighting device according to this embodiment may have a heat dissipation section. The heat dissipation section releases heat from inside the device to the outside, and examples include metals with high specific heat, liquid silicon, etc.

[0224] Figures 6A and 6B are schematic diagrams of an automobile, which is an example of a mobile body according to this embodiment. The automobile has a taillight, which is an example of a lighting device. The automobile 1500 has a taillight 1501, and may be configured to illuminate when the brakes are applied or the like.

[0225] The tail lamp 1501 may have an organic light-emitting element according to this embodiment. The tail lamp may have a protective member to protect the organic EL element. The protective member has a reasonably high strength and can be made of any transparent material, but it is preferably made of polycarbonate or the like. A frangic acid derivative, an acrylonitrile derivative, or the like may be mixed with the polycarbonate.

[0226] The automobile 1500 may have a body 1503 and windows 1502 attached thereto. The windows may be transparent displays, unless they are windows for checking the front and rear of the automobile. The transparent displays may have organic light-emitting elements according to this embodiment. In this case, the constituent materials such as electrodes of the organic light-emitting element are made of transparent materials.

[0227] Furthermore, as shown in Figure 6B, the automobile 1500 includes a steering wheel 1504 for controlling the direction of movement of the moving body, a display unit 1505 mounted on the vehicle body 1503 for displaying a map, the position of the moving body, the direction of turns, etc. The display unit 1505 may also have an organic light-emitting device according to this embodiment.

[0228] The mobile body according to this embodiment includes a drive force generating unit that generates a driving force mainly used for the movement of the mobile body, and one or both of a rotating body mainly used for the movement of the mobile body. The drive force generating unit may be an engine, a motor, etc. The rotating body may be a tire, a wheel, a ship's propeller, an aircraft's propeller, etc. Specifically, the mobile body may be a bicycle, an automobile, a train, a ship, an aircraft, a drone, etc. The mobile body may have a body and a light fixture or a display unit provided on the body. The light fixture may emit light to indicate the position of the body. The light fixture may have an organic light-emitting element according to this embodiment. The display unit may also have an organic light-emitting element according to the above embodiment.

[0229] Referencing Figures 7A and 7B, examples of applications of the display devices of each embodiment described above will be explained. The display device can be applied to systems that can be worn as wearable devices such as smart glasses, HMDs, and smart contact lenses. The imaging display device used in such applications comprises an imaging device capable of photoelectric conversion of visible light and a display device capable of emitting visible light.

[0230] Figure 7A illustrates a pair of eyeglasses 1600 (smart glasses) according to one application example. An imaging device 1602, such as a CMOS sensor or SPAD, is provided on the front surface of the lens 1601 of the eyeglasses 1600. In addition, the display devices of each embodiment described above are provided on the back surface of the lens 1601.

[0231] The eyeglasses 1600 further include a control device 1603. The control device 1603 functions as a power supply that provides power to the imaging device 1602 and the display device according to each embodiment. The control device 1603 also controls the operation of the imaging device 1602 and the display device. The lens 1601 has an optical system formed therein for focusing light onto the imaging device 1602.

[0232] Figure 7B illustrates a pair of glasses 1610 (smart glasses) according to one application example. The glasses 1610 have a control device 1612. The control device 1612 is equipped with an imaging device corresponding to an imaging device 1602 and a display device. An optical system is formed in the lens 1611 for projecting light emitted from the display device in the control device 1612, and an image is projected onto the lens 1611. The control device 1612 functions as a power supply that provides power to the imaging device and the display device, and also controls the operation of the imaging device and the display device. The control device may have a gaze detection unit that detects the wearer's gaze. Gaze detection may use infrared light. The infrared light emitter emits infrared light towards the eyeball of the user who is fixating on the displayed image. An image of the eyeball is obtained by detecting the reflected light from the eyeball of the emitted infrared light with an imaging unit having a photodetector. By having a reduction means that reduces the light from the infrared light emitter to the display unit in planar view, the deterioration of image quality is reduced.

[0233] The user's gaze towards the displayed image is detected from an image of the eyeball obtained by imaging with infrared light. Any known method can be applied to gaze detection using an image of the eyeball. For example, a gaze detection method based on the Purkinje image obtained by the reflection of the irradiated light from the cornea can be used.

[0234] More specifically, gaze detection processing is performed based on the pupil-corneal reflection method. Using the pupil-corneal reflection method, a gaze vector representing the orientation (rotation angle) of the eyeball is calculated based on the pupil image and Purkinje image contained in the captured image of the eyeball, thereby detecting the user's gaze.

[0235] A display device according to one embodiment of the present invention includes an imaging device having a light-receiving element, and may control the display image of the display device based on the user's gaze information from the imaging device.

[0236] Specifically, the display device determines a first display area that the user is fixated on, and a second display area other than the first display area, based on gaze information. The first and second display areas may be determined by the control device of the display device, or they may be determined by an external control device and received. Within the display areas of the display device, the display resolution of the first display area may be controlled to be higher than the display resolution of the second display area. In other words, the resolution of the second display area may be lower than that of the first field of view area.

[0237] Furthermore, the display area has a first display area and a second display area different from the first display area, and based on gaze information, the area with higher priority is determined from the first display area and the second display area. The first and second view areas may be determined by the control device of the display device, or they may be determined by an external control device and received. The resolution of the high-priority area may be controlled to be higher than the resolution of the areas other than the high-priority area. In other words, the resolution of areas with relatively lower priority may be lowered.

[0238] AI may be used to determine the first display area and areas with high priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to the target object from the eye image, using the eye image and the direction the eye was actually looking in the image as training data. The AI ​​program may be installed in the display device, the imaging device, or an external device. If installed in an external device, it is transmitted to the display device via communication.

[0239] When display control is based on visual detection, this method is preferably applicable to smart glasses that further include an imaging device for capturing images of the surrounding environment. The smart glasses can display the captured external information in real time.

[0240] Figures 8A and 8B are schematic diagrams of an HMD (head-mounted display) 2301 as a display device according to one embodiment of the present invention. Figure 8A is a schematic diagram showing the head-mounted display and the observer wearing it. The HMD 2301 is worn on the observer's head. Reference numeral 2302 indicates the observer's right eye, and reference numeral 2303 indicates the observer's left eye. Display lenses 2304 and 2305 constitute the right eye eyepiece optical system OR1, and display lenses 2306 and 2307 constitute the left eye eyepiece optical system OL1. Each eyepiece optical system is a coaxial optical system composed of a plurality (two) of display lenses. The observer's right eye 2302 is positioned in the exit pupil ER1 of the right eye eyepiece optical system OR1, and the observer's left eye 2303 is positioned in the exit pupil EL1 of the left eye eyepiece optical system OL1. The exit pupil ER1 is located at a distance E1 from the right eye eyepiece optical system OR1. Similarly, the exit pupil EL1 is located at a distance E1 from the left eyepiece optical system OL1. Optical films 2314 are provided on the surface of the right eyepiece optical system OR1 (the surface on the right eye 2302 side) and the surface of the left eyepiece optical system OL1 (the surface on the left eye 2303 side) for lens protection and light focusing.

[0241] Reference numeral 2308 and 2309 indicate display devices for the right eye and left eye, respectively. These display devices may be the display devices according to Embodiment 1. Figure 8B is a schematic diagram showing an example in which a display device according to one embodiment of the present invention is connected to an external device, and shows the appearance of the HMD 2301 and the personal computer 2350 connected thereto. Each display device displays a display image (original image) corresponding to the image signal output from the personal computer 2350. In this configuration, the connection is wired, but it may also be wireless. Furthermore, the HMD 2301 may be a standalone device with an image processing device built inside.

[0242] The eyepiece optical systems OR1 and OL1 guide light from the display devices 2308 and 2309 to the exit pupils ER1 and EL1, respectively, projecting an enlarged virtual image of the displayed image onto the observer's right eye 2302 and left eye 2303. This allows the observer to view the displayed image (or virtual image) shown on the display devices 2308 and 2309 through the eyepiece optical systems OR1 and OL1.

[0243] Although not shown in the diagram, the HMD2301 may have a control device. The control device functions as a power supply that provides power to the display devices 2308 and 2309, and also controls the operation of the display devices 2308 and 2309.

[0244] Figures 9A to 9C represent an image forming apparatus. Figure 9A is a schematic diagram of the image forming apparatus 1700 according to this embodiment. The image forming apparatus includes a photoreceptor, an exposure light source, a developing unit, a charging unit, a transfer unit, a transport roller, and a fuser.

[0245] Light 1709 is irradiated from the exposure light source 1708, and an electrostatic latent image is formed on the surface of the photoreceptor 1707. The exposure light source 1708 has an organic light-emitting element. The developing unit 1711 has toner or the like. The charging unit 1710 charges the photoreceptor 1707. The transfer unit 1712 transfers the developed image to the recording medium 1714. The transport unit 1713 transports the recording medium 1714. The recording medium 1714 is, for example, paper. The fixing unit 1715 fixes the image formed on the recording medium 1714.

[0246] Figures 9B and 9C are schematic diagrams showing how multiple light-emitting units 1726 are arranged on a long substrate in an exposure light source 1708. 1727 is parallel to the axis of the photoreceptor 1707 and represents the column direction in which the light-emitting units 1726, each having an organic light-emitting element, are arranged. This column direction is the same as the direction of the axis of rotation of the photoreceptor 1727. This direction can also be called the long axis direction of the photoreceptor 1727.

[0247] Figure 9B shows a configuration in which the light-emitting units 1726 are arranged along the long axis of the photoreceptor. Figure 9C shows a different configuration from Figure 9B, in which the light-emitting units 1726 are arranged alternately in the column direction in the first and second columns, respectively. The first and second columns are positioned at different locations in the row direction.

[0248] The first row has multiple light-emitting units 1726 arranged at intervals. The second row has light-emitting units 1726 at positions corresponding to the intervals between the light-emitting units 1726 in the first row. That is, multiple light-emitting units 1726 are also arranged at intervals in the row direction.

[0249] The arrangement in Figure 9C can also be described as a grid pattern, a houndstooth pattern, or a checkerboard pattern.

[0250] As described above, by using the device employing the organic light-emitting element according to this embodiment, stable display with good image quality is possible even during long-term display.

[0251] The present invention will be described below with reference to examples. However, the present invention is not limited to these examples. In the table in the examples, "%" refers to "mass%". The organic compounds used in these examples are as follows.

[0252]

[0253]

[0254]

[0255]

[0256]

[0257] <Example 1> <Fabrication of Organic Light-Emitting Device> In this example, a blue organic light-emitting device with a bottom emission structure was fabricated, in which an anode, hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, and cathode were sequentially formed on a substrate.

[0258] A 40 nm thick Ti film was deposited on a glass substrate using sputtering, and the pattern was created using photolithography to form the anode. The electrode area of ​​the anode was 3 mm². ２ I made it so that it would look like that. Then I washed it.

[0259] Next, the electrode-equipped substrate prepared above is attached to the vacuum deposition apparatus (manufactured by ULVAC), and after preparing for the deposition of the deposition material, 1.33 × 10 －４ Pa(1 × 10) －６ The chamber was evacuated to Torr. Afterward, the chamber was UV / ozone cleaned. Then, each layer was fabricated according to the layer configuration shown in Table 13. Finally, the substrate was transferred to a glove box and sealed with a glass cap containing a desiccant in a nitrogen atmosphere to obtain an organic light-emitting element.

[0260]

[0261] <Evaluation> A voltage application device was connected to the obtained organic light-emitting element, and its characteristics were evaluated. Current-voltage characteristics were measured using a Hewlett-Packard 4140B microcurrent meter, and chromaticity was evaluated using a Topcon SR-3. Luminous intensity was measured using a Topcon BM7.

[0262] [Luminous Efficacy Ratio] The luminous efficiency ratio is 1000 cd / m². ２ The external quantum efficiency during display was measured and expressed as a ratio when the efficiency of the element in Comparative Example 1 was set to 1.0. The results are shown in Table 16.

[0263] [Element Durability Ratio] The element durability ratio is based on an initial brightness of 5000 cd / m². ２ A continuous operation test was conducted, and the brightness was measured after 100 hours. The results are shown as a ratio with the brightness of the element in Comparative Example 1 set to 1.0. The results are shown in Table 16.

[0264] [Pz Value] The Pz value was measured using a Hamamatsu Photonics "Molecular Orientation Characterization Measuring Instrument C13472-01" after fabricating a thin film on a quartz glass substrate by vacuum deposition. The thin film used for the measurement was vacuum deposited to a thickness of 30 nm with the same composition ratio as the light-emitting layer, without heating the substrate, while adjusting the total deposition rate of each constituent material to 1 Å / s. Subsequently, this substrate was glass-sealed and measured using the above instrument. The Pz value was determined by inputting the refractive index of the substrate and the thin film, and the thickness of the thin film, into the instrument's software and performing an optical simulation. The operation was performed at room temperature from vacuum deposition to the end of the measurement. The results are shown in Table 16.

[0265] [PLQY] PLQY was fabricated on quartz glass using a vacuum deposition method to create a 30 nm film with a ratio of 99% by mass of one type of host material and 1% by mass of a guest material. The thin film was then measured using Hamamatsu Photonics' "Absolute PL Quantum Yield Analyzer". The results are shown in Table 16.

[0266] <Examples 2 to 46, Comparative Examples 1 to 5> Organic light-emitting devices were fabricated in the same manner as in Example 1, except that the composition of the organic compound layer was changed as shown in Tables 14 and 15, and their characteristics were evaluated. The results are shown in Tables 16 and 17.

[0267]

[0268]

[0269]

[0270]

[0271] <<Effects of having a guest material orientation degree Pz value of 0.1 or less>> Comparing Examples 1 and 46 with Comparative Examples 1 and 5, Example 1 and 46, which has a Pz value of 0.1 or less, shows higher luminous efficiency ratio and durability ratio in its device characteristics. This is because a smaller Pz value makes it easier for light generated inside the device to be emitted outside the substrate.

[0272] <<Effects of the first host material having two or more Unit ARs>> Unit AR has sp carbon atoms as the carbon atoms constituting the ring. ３ Although it is a condensed polycyclic aromatic group with three or more rings that does not contain carbon, the first host material having two or more of these groups has a broad π-conjugated plane. Comparing Example 1 and Comparative Example 2, Example 1, which has two unit ARs, has a higher durability ratio of device characteristics. This is because the first host material of Example 1 has a broad π-conjugated plane, which suppresses the formation of charge accumulation.

[0273] <<Effects of the second host material being a compound represented by general formula [1] or general formula [2]>> Comparing Example 1 with Comparative Example 3, Example 1, in which the second host material is represented by general formula [1], shows higher luminous efficiency ratio and durability ratio of the device characteristics. This is because the second host material of Example 1 has a pyrene structure that can efficiently generate singlet excitons from a triplet excited state, while also having an asymmetric molecular structure, thereby increasing the number of singlet excitons and exhibiting excellent dispersibility of the guest material.

[0274] <<Example 47>> A green organic light-emitting element was fabricated in the same manner as in Example 1, except that the organic compound layer and electrode layer shown in Table 18 were continuously deposited on an ITO substrate. The characteristics of the obtained element were evaluated in the same manner as in Example 1. The luminous efficiency ratio and element durability ratio are shown as ratios with Comparative Example 6 set to 1.0. The results are shown in Table 19.

[0275]

[0276] Examples 48 to 50, Comparative Example 6: Organic light-emitting devices were fabricated in the same manner as in Example 47, except that the guest material and host material were changed as shown in Table 19, and their characteristics were evaluated. The results are shown in Table 19.

[0277]

[0278] As shown in Examples 47 to 50, excellent device characteristics were confirmed in the green organic light-emitting device of this embodiment.

[0279] <<Example 51>> A red organic light-emitting element was fabricated in the same manner as in Example 1, except that the organic compound layer and electrode layer shown in Table 20 were continuously deposited on an ITO substrate. The characteristics of the obtained element were evaluated in the same manner as in Example 1. The luminous efficiency ratio and element durability ratio are shown as ratios with Comparative Example 7 set to 1.0. The results are shown in Table 21.

[0280]

[0281] <<Example 52, Comparative Example 7>> Organic light-emitting devices were fabricated in the same manner as in Example 51, except that the guest material and host material were changed as shown in Table 21, and their characteristics were evaluated. The results are shown in Table 21.

[0282]

[0283] As shown in Examples 51 to 52, excellent device characteristics were confirmed in the red organic light-emitting element of this embodiment.

[0284] In the above-described examples, the materials used to constitute the light-emitting layer included a guest material which is a compound with a horizontal orientation degree Pz value of 0.1 or less, a first host material which is a compound having two or more units AR, and a second host material which is a compound represented by general formula [1] or general formula [2]. As a result, a synergistic effect was achieved between the first host material responsible for charge transport, the second host material which has excellent dispersibility with the guest material, and the guest material with high orientation, making it possible to provide an organic light-emitting element with excellent luminescence efficiency and durability.

[0285] <Included Configurations> The disclosure of this embodiment includes the following configurations.

[0286] (Configuration 1) An organic light-emitting element having two electrodes and a light-emitting layer disposed between the two electrodes, wherein the light-emitting layer comprises a first host material, a second host material and a guest material, the guest material is a compound with an orientation degree Pz value of 0.1 or less, the first host material is a compound having two or more units AR, and the units AR have sp carbon atoms constituting a ring ３ An organic light-emitting element characterized in that the second host material is a compound represented by general formula [1] or general formula [2], wherein the second host material is a condensed polycyclic aromatic group of three or more rings that does not contain carbon.

[0287] (Configuration 2) The Ar １ is selected from substituted or unsubstituted aryl groups, and the Ar ２ The organic light-emitting element according to configuration 1, characterized in that it is selected from a hydrogen atom, a substituted or unsubstituted aryl group.

[0288] (Configuration 3) The R １ ~R ８ The organic light-emitting element according to configuration 1 or 2, characterized in that each is independently selected from a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, an aryl group consisting of two or fewer substituted rings, and a heteroaryl group consisting of two or fewer substituted rings.

[0289] (Configuration 4) The organic light-emitting element according to any one of Configurations 1 to 3, characterized in that the unit AR is independently selected from pyrene residues, anthracene residues, triphenylene residues, phenanthrene residues, perylene residues, chrysene residues, tetracene residues, and fluorantene residues.

[0290] (Configuration 5) The organic light-emitting element according to any one of Configurations 1 to 4, characterized in that at least two of the units AR are the same group.

[0291] (Configuration 6) An organic light-emitting element according to any one of Configurations 1 to 5, characterized in that the photoluminescence quantum yield (PLQY) when the same guest material is mixed with the host material at the same concentration is higher for the second host material than for the first host material.

[0292] (Configuration 7) An organic light-emitting element according to any one of Configurations 1 to 6, characterized in that it satisfies the following formula (I): PAS-Ratio (first host material) > PAS-Ratio (second host material) (I) (In formula (I), PAS-Ratio is the molecular weight of the compound, with sp as the carbon atoms constituting the ring. ３ (This represents the ratio of molecular weights of three or more condensed polycyclic aromatic groups that do not contain carbon.)

[0293] (Configuration 8) The organic light-emitting element according to any one of Configurations 1 to 7, characterized in that the guest material is a hydrocarbon compound.

[0294] (Configuration 9) The organic light-emitting element according to any one of Configurations 1 to 8, characterized in that the first host material and the second host material are hydrocarbon compounds.

[0295] (Configuration 10) The organic light-emitting element according to any one of Configurations 1 to 9, characterized in that the first host material is a compound represented by general formula [3].

[0296] (Configuration 11) The second host material is sp ３ An organic light-emitting element according to any one of configurations 1 to 10, characterized by containing carbon.

[0297] (Configuration 12) The organic light-emitting element according to any one of Configurations 1 to 11, characterized in that the second host material is a compound represented by general formula [4].

[0298] (Configuration 13) The carbon atoms contained in the first host material are sp ２ An organic light-emitting element according to any one of configurations 1 to 12, characterized in that it consists only of carbon.

[0299] (Configuration 14) An organic light-emitting element according to any one of Configurations 1 to 13, characterized in that it satisfies the following formula (II): Mass ratio of the first host material in the light-emitting layer [mass%] / Mass ratio of the second host material in the light-emitting layer [mass%] ≥ 1 (II)

[0300] (Configuration 15) The organic light-emitting element according to any one of Configurations 1 to 14, characterized in that the guest material is a compound with an orientation degree Pz value of 0.06 or less.

[0301] (Configuration 16) A display device having a plurality of pixels, wherein at least one of the plurality of pixels has an organic light-emitting element according to any one of Configurations 1 to 14 and a transistor connected to the organic light-emitting element.

[0302] (Configuration 17) A photoelectric conversion device comprising an optical unit having a plurality of lenses, an image sensor that receives light that has passed through the optical unit, and a display unit that displays an image captured by the image sensor, wherein the display unit has an organic light-emitting element as described in any of Configurations 1 to 14.

[0303] (Configuration 18) An electronic device comprising: a display unit having an organic light-emitting element as described in any of Configurations 1 to 14; a housing on which the display unit is provided; and a communication unit provided in the housing for communicating with the outside.

[0304] (Configuration 19) A lighting device characterized by comprising a light source having an organic light-emitting element as described in any of Configurations 1 to 14, and a light-diffusing part or optical film that transmits the light emitted by the light source.

[0305] (Configuration 20) A mobile body characterized by having a light fixture having an organic light-emitting element as described in any of Configurations 1 to 14, and a body on which the light fixture is provided.

[0306] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public.

[0307] This application claims priority based on Japanese Patent Application No. 2025-013112, filed on 29 January 2025, and all of its contents are incorporated herein by reference.

[0308] 1. Interlayer insulating layer 2. First electrode 3. Insulating layer 4. Organic compound layer 5. Second electrode 6. Protective layer 7. Color filter 10. Sub-pixel 11. Substrate 12. Insulating layer 13. Gate electrode 14. Gate insulating film 15. Semiconductor layer 16. Drain electrode 17. Source electrode 18. TFT 19. Insulating film 20. Contact hole 21. Anode 22. Organic compound layer 23. Cathode 24. First protective layer 25. Second protective layer 26. Organic light-emitting element 100. Display device

Claims

1. An organic light-emitting element having two electrodes and a light-emitting layer disposed between the two electrodes, wherein the light-emitting layer comprises a first host material, a second host material, and a guest material, the guest material being a compound with an orientation degree Pz value of 0.1 or less, the first host material being a compound having two or more units AR, and the units AR being composed of carbon atoms constituting a ring, sp ３ An organic light-emitting element characterized in that the second host material is a compound represented by the following general formula [1] or general formula [2], wherein the second host material is a condensed polycyclic aromatic group of three or more rings that does not contain carbon. (In general formula [1] or general formula [2], Ar １ and Ar ２ These are different groups, Ar １ Ar is selected from substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups. ２ R is selected from a hydrogen atom, a deuterium atom, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. １ ~R ８ Each of these is independently selected from hydrogen atoms, deuterium atoms, halogen atoms, cyano groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted silyl groups, substituted or unsubstituted aryl groups consisting of two or fewer rings, and substituted or unsubstituted heteroaryl groups consisting of two or fewer rings.

2. The Ar １ is selected from a substituted or unsubstituted aryl group, and the Ar ２ is selected from a hydrogen atom, a substituted or unsubstituted aryl group. The organic light-emitting device according to claim 1, characterized in that.

3. The aforementioned R １ ~R ８ The organic light-emitting element according to claim 1 is characterized in that each of the following is independently selected from a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, an aryl group consisting of two or fewer substituted rings, and a heteroaryl group consisting of two or fewer substituted rings.

4. The organic light-emitting element according to claim 1, characterized in that the unit AR is independently selected from pyrene residues, anthracene residues, triphenylene residues, phenanthrene residues, perylene residues, chrysene residues, tetracene residues, and fluorantene residues.

5. The organic light-emitting element according to claim 1, characterized in that at least two of the units AR are the same group.

6. The organic light-emitting element according to claim 1, characterized in that the photoluminescence quantum yield (PLQY) when the same guest material is mixed with the host material at the same concentration is higher for the second host material than for the first host material.

7. The organic light-emitting element according to claim 1, characterized in that it satisfies the following formula (I): PAS-Ratio (first host material) > PAS-Ratio (second host material) (I) (In formula (I), PAS-Ratio is the molecular weight of the compound, with sp as the carbon atoms constituting the ring) ３ (This represents the ratio of molecular weights of three or more condensed polycyclic aromatic groups that do not contain carbon.) 8. The organic light-emitting element according to claim 1, characterized in that the guest material is a hydrocarbon compound.

9. The organic light-emitting element according to claim 1, characterized in that the first host material and the second host material are hydrocarbon compounds.

10. The organic light-emitting element according to claim 1, characterized in that the first host material is a compound represented by the following general formula [3]. (In general formula [3], Ar is a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group. R is independently selected from a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. l and m each represent an integer between 0 and 9.) 11. The second host material is sp ３ The organic light-emitting element according to claim 1, characterized by containing carbon.

12. The organic light-emitting element according to claim 1, characterized in that the second host material is a compound represented by the following general formula [4]. (In general formula [4], R １１ ~R ２６ , R ３１ ~R ３９ Each of the following is independently selected: hydrogen atom, deuterium atom, halogen atom, cyano group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted silyl group, substituted or unsubstituted aryl group consisting of two or fewer rings, and substituted or unsubstituted heteroaryl group consisting of two or fewer rings. However, R １１ ~R １４ One of these is bonded to a pyrene ring. n represents an integer between 0 and 3. When n is 2 or greater, R ３１ ~R ３４ (This may differ for each repeating unit.) 13. The carbon atoms contained in the first host material are sp ２ The organic light-emitting element according to claim 1, characterized in that it consists only of carbon.

14. The organic light-emitting element according to claim 1, characterized in that it satisfies the following formula (II): Mass ratio of the first host material in the light-emitting layer [mass%] / Mass ratio of the second host material in the light-emitting layer [mass%] ≥ 1 (II) 15. The organic light-emitting element according to claim 1, characterized in that the guest material is a compound with an orientation degree Pz value of 0.06 or less.

16. A display device having a plurality of pixels, wherein at least one of the plurality of pixels comprises an organic light-emitting element according to any one of claims 1 to 15 and a transistor connected to the organic light-emitting element.

17. A photoelectric conversion device comprising an optical unit having a plurality of lenses, an image sensor that receives light that has passed through the optical unit, and a display unit that displays an image captured by the image sensor, wherein the display unit has an organic light-emitting element as described in any one of claims 1 to 15.

18. An electronic device comprising: a display unit having an organic light-emitting element as described in any one of claims 1 to 15; a housing on which the display unit is provided; and a communication unit provided in the housing for communicating with the outside.

19. A lighting device comprising a light source having an organic light-emitting element as described in any one of claims 1 to 15, and a light-diffusing portion or optical film that transmits light emitted by the light source.

20. A mobile body characterized by comprising a lamp having an organic light-emitting element as described in any one of claims 1 to 15, and a body on which the lamp is provided.

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