JP7427262B2 - organic electroluminescent device - Google Patents

Description

The present invention relates to an organic electroluminescent device (hereinafter sometimes referred to as an organic EL device).

Organic EL devices are known that include a host compound that is a charge transporting material and a phosphorescent material in a light emitting layer (for example, see Patent Document 1).

International Publication No. 2005/112520

In an organic EL element containing a host compound and a phosphorescent material in the emitting layer (hereinafter sometimes referred to as a host compound-containing element), when the concentration of the phosphorescent material in the emitting layer is increased, the organic EL element The luminous efficiency (hereinafter sometimes simply referred to as "luminous efficiency") may decrease. On the other hand, in a host compound-containing device, the lower the concentration of the phosphorescent material in the light emitting layer, the lower the efficiency of energy transfer between the host compound and the phosphorescent material tends to be.

Therefore, in a host compound-containing device, the optimal concentration of the phosphorescent material in the light emitting layer is approximately 6% by mass or more and 8% by mass or less. Therefore, in host compound-containing devices, when forming a light-emitting layer, the permissible range (process margin) of the concentration of the phosphorescent material tends to become narrow, so it may be difficult to improve productivity.

The present invention has been made in view of the above problems, and its purpose is to provide an organic EL element with high productivity.

The organic EL device according to the present invention includes an anode, a cathode, and a light emitting layer provided between the anode and the cathode. The light-emitting layer contains a platinum complex represented by the following general formula (I), the following general formula (II), the following general formula (III), or the following general formula (IV).

In the general formula (I), the general formula (II), the general formula (III), and the general formula (IV), n1 and n2 are each independently an integer of 2 or more and 20 or less. R ¹ and R ² each independently represent a halogen atom, an alkyl group having 1 to 32 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkynyl group having 2 to 16 carbon atoms, and a carbon atom. Cycloalkyl group having 5 to 8 carbon atoms, alkoxy group having 1 to 16 carbon atoms, amino group, alkylamino group having 1 to 16 carbon atoms, hydroxy group, carboxy group, having 2 to 17 carbon atoms They are an alkoxycarbonyl group, a phenyl group, a phenoxy group, a nitrile group, a nitro group, or a thiol group. R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a halogen atom, an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, and 2 to 16 carbon atoms. Alkynyl group, cycloalkyl group having 5 to 8 carbon atoms, alkoxy group having 1 to 16 carbon atoms, amino group, alkylamino group having 1 to 16 carbon atoms, hydroxy group, carboxy group, carbon atom It is an alkoxycarbonyl group, a phenyl group, a phenoxy group, a nitrile group, a nitro group, or a thiol group having a number of 2 or more and 17 or less. a and c are each independently an integer of 0 or more and 2 or less. b and d are each independently an integer of 0 or more and 4 or less.

In one embodiment, a, b, c, and d in the general formula (I), the general formula (II), the general formula (III), and the general formula (IV) are 0.

In one embodiment, the light-emitting layer contains a platinum complex represented by the general formula (I) or the general formula (II).

In one embodiment, the light-emitting layer includes a platinum complex represented by the general formula (III) or the general formula (IV), and in the general formula (III) and the general formula (IV), R ¹ and Each R ² is independently an alkyl group having 1 or more and 32 or less carbon atoms.

In one embodiment, the light-emitting layer includes a platinum complex represented by the following chemical formula (1).

In one embodiment, the light emitting layer further includes a host compound.

According to the present invention, it is possible to provide an organic EL element with high productivity.

1 is a cross-sectional view showing an example of the structure of an organic EL element according to an embodiment of the present invention. It is a graph showing the relationship between voltage and current density in an organic EL element of an example. It is a graph showing the emission spectrum of the organic EL element of the example. It is a graph showing the relationship between voltage and brightness in an organic EL element of an example. It is a graph showing the relationship between current density and external quantum efficiency in an organic EL element of an example.

Hereinafter, preferred embodiments of the present invention will be described. Note that the description may be omitted as appropriate for parts where the description overlaps, but this does not limit the gist of the invention.

First, terms used in this specification will be explained. "Halogen atom" means a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. As the halogen atom, a fluorine atom is preferred.

"Alkyl group having 1 to 16 carbon atoms" is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 16 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, and dodecyl group. , tridecyl group, tetradecyl group, pentadecyl group and hexadecyl group. The alkyl group having 1 to 16 carbon atoms is preferably an alkyl group having 1 to 13 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and an alkyl group having 1 to 5 carbon atoms. is even more preferable.

The "alkyl group having 1 to 32 carbon atoms" is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 32 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, and dodecyl group. , tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacyl group, octacosyl group, nonacosyl group group, triacontyl group, hentriacontyl group, and dotriacontyl group. The alkyl group having 1 to 32 carbon atoms is preferably an alkyl group having 4 to 24 carbon atoms, more preferably an alkyl group having 4 to 20 carbon atoms, and an alkyl group having 5 to 16 carbon atoms. is even more preferable.

The "alkenyl group having 2 to 16 carbon atoms" is linear or branched and unsubstituted. Examples of the alkenyl group having 2 to 16 carbon atoms include vinyl group, allyl group, isopropenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decynyl group, undecynyl group, Examples include dodecynyl group, tridodecynyl group, tetradecynyl group, pentadecynyl group and hexadecynyl group. The alkenyl group having 2 to 16 carbon atoms is preferably an alkenyl group having 2 to 12 carbon atoms, more preferably an alkenyl group having 2 to 10 carbon atoms, and an alkenyl group having 2 to 8 carbon atoms. is even more preferable. In addition, in the alkenyl group having 2 or more and 16 or less carbon atoms, the position of the double bond is not limited.

The "alkynyl group having 2 to 16 carbon atoms" is linear or branched and unsubstituted. Examples of the alkynyl group having 2 or more and 16 or less carbon atoms include an acetylenyl group, a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, a heptynyl group, and an octynyl group. The alkynyl group having 2 to 16 carbon atoms is preferably an alkynyl group having 2 to 12 carbon atoms, more preferably an alkynyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 8 carbon atoms. is even more preferable. In addition, in the alkynyl group having 2 or more and 16 or less carbon atoms, the position of the triple bond is not limited.

A "cycloalkyl group having 5 to 8 carbon atoms" is an unsubstituted cyclic alkyl group having 5 to 8 carbon atoms. Examples of the cycloalkyl group having 5 to 8 carbon atoms include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. The cycloalkyl group having 5 to 8 carbon atoms is preferably a cycloalkyl group having 5 to 7 carbon atoms, and more preferably a cyclopentyl group or a cyclohexyl group.

"Alkoxy group having 1 to 16 carbon atoms" is linear or branched and unsubstituted. Examples of the alkoxy group having 1 to 16 carbon atoms include methoxy group, ethoxy group, propyloxy group, butyloxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy group, Examples include undecyloxy group, dodecyloxy group, tridecyloxy group, tetradecyloxy group, pentadecyloxy group and hexadecyloxy group. The "alkoxy group having 1 to 16 carbon atoms" is preferably an alkoxy group having 1 to 13 carbon atoms, more preferably an alkoxy group having 1 to 8 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. More preferred is an alkoxy group.

The "alkylamino group having 1 to 16 carbon atoms" is linear or branched and unsubstituted. Examples of the alkylamino group having 1 to 16 carbon atoms include methylamino group, ethylamino group, propylamino group, butylamino group, pentylamino group, hexylamino group, heptylamino group, octylamino group, and nonylamino group. , decylamino group, undecylamino group, dodecylamino group, tridecylamino group, tetradecylamino group, pentadecylamino group and hexadecylamino group. The alkylamino group having 1 to 16 carbon atoms is preferably an alkylamino group having 1 to 13 carbon atoms, more preferably an alkylamino group having 1 to 8 carbon atoms.

"Alkoxycarbonyl group having 2 to 17 carbon atoms" means a group in which an alkoxy group and a carbonyl group are bonded, and the total number of carbon atoms is 2 to 17. The alkoxycarbonyl group having 2 or more and 17 or less carbon atoms is unsubstituted, and the alkoxy group moiety is linear or branched. Examples of the alkoxycarbonyl group having 2 to 17 carbon atoms include methoxycarbonyl group, ethoxycarbonyl group, propyloxycarbonyl group, butyloxycarbonyl group, pentyloxycarbonyl group, hexyloxycarbonyl group, heptyloxycarbonyl group, and octyl group. Examples include oxycarbonyl group, nonyloxycarbonyl group, decyloxycarbonyl group, undecyloxycarbonyl group, dodecyloxycarbonyl group, tridecyloxycarbonyl group, tetradecyloxycarbonyl group, pentadecyloxycarbonyl group and hexadecyloxycarbonyl group. It will be done. The alkoxycarbonyl group having 2 to 17 carbon atoms is preferably an alkoxycarbonyl group having 2 to 14 carbon atoms, more preferably an alkoxycarbonyl group having 2 to 9 carbon atoms, and 2 to 6 carbon atoms. More preferred is an alkoxycarbonyl group.

The "host compound" is a material that has charge transport performance, and is a compound that plays the role of, for example, donating energy to the phosphorescent material (platinum complex) in the light emitting layer.

<Organic EL element>
The organic EL device according to this embodiment includes an anode, a cathode, and a light emitting layer provided between the anode and the cathode. The light-emitting layer contains a platinum complex represented by the following general formula (I), the following general formula (II), the following general formula (III), or the following general formula (IV).

In general formula (I), general formula (II), general formula (III) and general formula (IV), n1 and n2 are each independently an integer of 2 or more and 20 or less. R ¹ and R ² each independently represent a halogen atom, an alkyl group having 1 to 32 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkynyl group having 2 to 16 carbon atoms, and a carbon atom. Cycloalkyl group having 5 to 8 carbon atoms, alkoxy group having 1 to 16 carbon atoms, amino group, alkylamino group having 1 to 16 carbon atoms, hydroxy group, carboxy group, having 2 to 17 carbon atoms They are an alkoxycarbonyl group, a phenyl group, a phenoxy group, a nitrile group, a nitro group, or a thiol group. R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a halogen atom, an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, and 2 to 16 carbon atoms. Alkynyl group, cycloalkyl group having 5 to 8 carbon atoms, alkoxy group having 1 to 16 carbon atoms, amino group, alkylamino group having 1 to 16 carbon atoms, hydroxy group, carboxy group, carbon atom It is an alkoxycarbonyl group, a phenyl group, a phenoxy group, a nitrile group, a nitro group, or a thiol group having a number of 2 or more and 17 or less. a and c are each independently an integer of 0 or more and 2 or less. b and d are each independently an integer of 0 or more and 4 or less.

Hereinafter, platinum complexes represented by general formula (I), general formula (II), general formula (III), and general formula (IV) will be referred to as platinum complex (I), platinum complex (II), and platinum complex (III), respectively. ) and platinum complex (IV). Further, at least one platinum complex selected from the group consisting of platinum complex (I), platinum complex (II), platinum complex (III), and platinum complex (IV) may be described as a specific platinum complex. The organic EL device of this embodiment includes one or more specific platinum complexes as a phosphorescent material in the light emitting layer.

According to this embodiment, an organic EL element with high productivity can be provided. The reason is assumed to be as follows.

In the organic EL device according to this embodiment, the light emitting layer contains a specific platinum complex. The specific platinum complex has a chelate ligand having an iminopyrazole skeleton. More specifically, the ligand possessed by the specific platinum complex has a structure (or partial structure) represented by the following general formula (V). Hereinafter, a ligand having the structure (or partial structure) represented by general formula (V) may be referred to as an IP ligand. In general formula (V), R ^A is a part of -(CH ₂ ) _n1 - in general formula (I), a part of -(CH ₂ ) _n2 - in general formula (II), or a general R ¹ in formula (III) or R ² in general formula (IV).

Since the specific platinum complex has two IP ligands, it tends to be difficult to deactivate (quench) even if it is contained in the light emitting layer at a high concentration. Therefore, the organic EL device of this embodiment exhibits high luminous efficiency regardless of the concentration of the specific platinum complex in the luminescent layer. Therefore, in the organic EL device of this embodiment, there is no need to strictly adjust the concentration of the specific platinum complex when forming the light emitting layer, so a wide process margin can be ensured. Therefore, according to this embodiment, an organic EL element with high productivity can be provided.

[Specific platinum complex]
The specific platinum complex will be explained in detail below.

In order to further increase the luminous efficiency, R ^A in the general formula (V) is a group containing a hydrogen atom (more specifically, an alkyl group having 1 to 32 carbon atoms, -(CH ₂ ) _n1 -). (a part of --(CH ₂ ) _n2 --, etc.) is preferable. The reason why the specific platinum complex in which R ^A is a group containing a hydrogen atom can further increase the luminous efficiency is presumed as follows. When R ^A is a group containing a hydrogen atom, in the specific platinum complex, between the hydrogen atom of R ^A in one IP ligand and the nitrogen atom constituting the pyrazole ring of the other IP ligand. It is thought that the planarity of the specific platinum complex increases due to the formation of intramolecular hydrogen bonds. Since phosphorescent materials with high planarity tend to be difficult to deactivate (quench), it is thought that a specific platinum complex in which R ^A is a group containing a hydrogen atom can further improve luminous efficiency.

In order to further increase luminous efficiency, as specific platinum complexes, platinum complexes (I) in which a in the general formula (I) is 0, and platinum complexes (II) in which b in the general formula (II) is 0. , a platinum complex (III) in which c in the general formula (III) is 0, or a platinum complex (IV) in which d in the general formula (IV) is 0.

In order to further increase luminous efficiency, the specific platinum complex is preferably platinum complex (I) or platinum complex (II), and platinum complex (I) in which n1 in the general formula (I) is an integer of 8 or more and 15 or less. ), or a platinum complex (II) in which n2 in the general formula (II) is an integer of 8 or more and 15 or less is more preferable. The reason why the luminous efficiency becomes higher when platinum complex (I) or platinum complex (II) is used as the specific platinum complex is presumed as follows. The platinum complex (I) is a cross-ring complex in which the nitrogen atoms of two IP ligands are bridged by an alkylene group represented by -(CH ₂ ) _n1 - in the general formula (I). . In addition, platinum complex (II) is a cross-ring type complex in which nitrogen atoms of two IP ligands are bridged by an alkylene group represented by -(CH ₂ ) _n2 - in general formula (II). It is. In the platinum complex (I) and platinum complex (II), in the crystal state, the positions of each complex molecule are fixed by the crosslinked structure part, resulting in higher planarity, and thermal deactivation due to molecular vibration. It is thought that this can be suppressed. Therefore, it is considered that the luminous efficiency is further increased when platinum complex (I) or platinum complex (II) is used as the specific platinum complex. The specific platinum complexes include platinum complexes (I) in which n1 in the general formula (I) is an integer of 8 to 15, and platinum complexes in which n2 in the general formula (II) is an integer of 8 to 15. When (II) is used together, n1 and n2 may be the same or different.

In addition, when the light-emitting layer contains a platinum complex (III) or a platinum complex (IV), in order to further increase the light-emitting efficiency, in the light-emitting layer, R ¹ in the general formula (III) has a carbon atom number of 1 or more and 32 or less. It is preferable to include a platinum complex (III) which is an alkyl group of the general formula (IV), or a platinum complex (IV) where R ² in the general formula (IV) is an alkyl group having 1 or more and 32 or less carbon atoms. It is more preferable to include a platinum complex (III) in which R ¹ is an alkyl group having 1 or more and 32 or less carbon atoms. Specific platinum complexes include platinum complexes (III) in which R ¹ in the general formula (III) is an alkyl group having 1 to 32 carbon atoms, and platinum complexes (III) in which R ² in the general formula (IV) is an alkyl group having 1 to 32 carbon atoms; When using platinum complex (IV) which is an alkyl group of 32 or less, R ¹ and R ² may be the same or different.

When the light-emitting layer contains a platinum complex (I), in order to further increase the light-emitting efficiency, the platinum complex (I) contained in the light-emitting layer should be such that n1 in the general formula (I) is an integer of 8 or more and 15 or less. A platinum complex (I) in which n1 in the general formula (I) is an integer of 9 or more and 13 or less is more preferable, and a platinum complex (I) in which n1 in the general formula (I) is an integer of 9 or more and 12 or less is preferable. More preferred are platinum complexes (I) that are integers.

In addition, when the light-emitting layer contains a platinum complex (I), in order to further increase the light-emitting efficiency, the platinum complex (I) contained in the light-emitting layer should be such that n1 in the general formula (I) is 8 or more and 15 or less. is an integer, and a in general formula (I) is preferably 0, and n1 in general formula (I) is an integer of 9 or more and 13 or less, and general formula (I) A platinum complex (I) in which a is 0 is more preferable, and a platinum complex (I) in which n1 in the general formula (I) is an integer of 9 or more and 12 or less, and a in the general formula (I) is 0. I) is more preferred, and a platinum complex represented by the following chemical formula (1) (hereinafter sometimes referred to as compound (1)) is particularly preferred.

When the light-emitting layer contains a platinum complex (II), in order to further increase the light-emitting efficiency, the platinum complex (II) contained in the light-emitting layer should be such that n2 in the general formula (II) is an integer of 8 or more and 15 or less. A platinum complex (II) in which n2 in the general formula (II) is an integer of 9 or more and 13 or less is more preferable, and a platinum complex (II) in which n2 in the general formula (II) is an integer of 9 or more and 12 or less is preferable. More preferred is platinum complex (II) which is an integer.

In addition, when the light-emitting layer contains a platinum complex (II), in order to further increase the light-emitting efficiency, the platinum complex (II) contained in the light-emitting layer should be such that n2 in the general formula (II) is 8 or more and 15 or less. is an integer, and b in the general formula (II) is preferably 0, and n2 in the general formula (II) is an integer of 9 or more and 13 or less, and the general formula (II) A platinum complex (II) in which b is 0 is more preferable, and a platinum complex (II) in which n2 in the general formula (II) is an integer of 9 or more and 12 or less, and b in the general formula (II) is 0. II) is more preferred, and a platinum complex represented by the following chemical formula (2) is particularly preferred.

When the light-emitting layer contains a platinum complex (III), in order to further increase the light-emitting efficiency, the platinum complex (III) contained in the light-emitting layer should be such that R ¹ in the general formula (III) has one or more carbon atoms. A platinum complex (III) which is an alkyl group of 32 or less is preferable, a platinum complex (III) where R ¹ in the general formula (III) is an alkyl group having 4 or more and 24 or less carbon atoms is more preferable; Platinum complex (III) in which R ¹ in ) is an alkyl group having 4 or more and 20 or less carbon atoms is more preferred.

In addition, when the light-emitting layer contains a platinum complex (III), in order to further increase the light-emitting efficiency, the platinum complex (III) contained in the light-emitting layer should be such that R ¹ in the general formula (III) has a carbon atom number. Platinum complex (III) is preferably an alkyl group having 1 or more and 32 or less, and c in the general formula (III) is 0, and R ¹ in the general formula (III) is an alkyl group having 4 or more and 24 or less carbon atoms. A platinum complex (III) in which c in the general formula (III) is 0 is more preferable, and R ¹ in the general formula (III) is an alkyl group having 4 or more and 20 or less carbon atoms, and A platinum complex (III) in which c in the general formula (III) is 0 is more preferable, and a platinum complex (III) represented by the following chemical formula (3) (hereinafter sometimes referred to as compound (3)) or the following chemical formula ( The platinum complex represented by 4) (hereinafter sometimes referred to as compound (4)) is particularly preferred.

When the light-emitting layer contains a platinum complex (IV), in order to further increase the light-emitting efficiency, the platinum complex (IV) contained in the light-emitting layer should be such that R ² in the general formula (IV) has one or more carbon atoms. A platinum complex (IV) in which R 2 is an alkyl group having 32 or less carbon atoms is preferred, and a platinum complex (IV) in which R ² in the general formula (IV) is an alkyl group having 4 or more and 24 or less carbon atoms is more preferred. Platinum complex (IV) in which R ² in ) is an alkyl group having 4 or more and 20 or less carbon atoms is more preferred.

In addition, when the light-emitting layer contains a platinum complex (IV), in order to further increase the light-emitting efficiency, the platinum complex (IV) contained in the light-emitting layer should be such that R ² in the general formula (IV) has a carbon atom number. Platinum complex (IV) is preferably an alkyl group of 1 or more and 32 or less, and d in the general formula (IV) is 0, and R ² in the general formula (IV) is an alkyl group having 4 or more and 24 or less carbon atoms. A platinum complex (IV) in which d is 0 in the general formula (IV) is more preferable, and R ² in the general formula (IV) is an alkyl group having 4 to 20 carbon atoms, and A platinum complex (IV) in which d in the general formula (IV) is 0 is more preferred.

In order to particularly increase the luminous efficiency, the specific platinum complex is preferably platinum complex (I), more preferably a platinum complex (I) in which n1 in the general formula (I) is an integer of 8 or more and 15 or less; A platinum complex (I) in which n1 in formula (I) is an integer of 8 or more and 15 or less and a in general formula (I) is 0 is more preferred, and compound (1) is particularly preferred.

Platinum complex (I) is synthesized, for example, according to reaction formulas (RA-1) and (RA-2) below, or by a method analogous thereto. Hereinafter, the reactions represented by reaction formulas (RA-1) and (RA-2) may be referred to as reactions (RA-1) and (RA-2), respectively. In addition, R 11 , a and n1 in general formulas (XA), (XIA) and (XII) shown in reaction formula (RA-1) are R ¹¹ , a and ⁿ¹ in general formula (I), respectively. is synonymous with Furthermore, Pt-Com shown in reaction formula (RA-2) means a platinum compound.

In reaction (RA-1), an aldehyde derivative represented by general formula (XA) (hereinafter referred to as aldehyde derivative (XA)) and a diamine (from 0.5 molar equivalent to aldehyde derivative (XA)) Specifically, by heating the compound represented by the general formula (XIA) in a solvent, the compound represented by the general formula (XII) (hereinafter referred to as compound (XII)) is obtained. The reaction temperature of reaction (RA-1) is, for example, 20°C or more and 100°C or less. The reaction time of reaction (RA-1) is, for example, 1 hour or more and 48 hours or less. The solvent used in the reaction (RA-1) is not particularly limited, but includes, for example, methanol, ethanol, a mixture of dimethylformamide (hereinafter sometimes referred to as DMF) and methanol, and dimethyl sulfoxide (hereinafter referred to as (sometimes written as DMSO).

In reaction (RA-2), compound (XII) and a platinum compound are reacted in a solvent in the presence of a base to obtain platinum complex (I). Examples of platinum compounds include PtCl ₂ (CH ₃ CN) ₂ and K ₂ PtCl ₄ . Bases include, for example, K ₂ CO ₃ , NaH and triethylamine. The reaction temperature of reaction (RA-2) is, for example, 20°C or more and 130°C or less. The reaction time of reaction (RA-2) is, for example, 1 hour or more and 48 hours or less. The solvent used in reaction (RA-2) is not particularly limited, but includes, for example, a mixture of DMF and methanol, DMSO, and a mixture of toluene and DMSO.

Platinum complex (II) is synthesized, for example, according to reaction formulas (RB-1) and (RB-2) below, or by a method analogous thereto. Hereinafter, the reactions represented by reaction formulas (RB-1) and (RB-2) may be referred to as reactions (RB-1) and (RB-2), respectively. In addition, ^R 12 , b and n2 in general formulas (XVIA), (XIB) and (XIII) shown in reaction formula (RB-1) are R ¹² , b and n2 in general formula (II), respectively. is synonymous with Furthermore, Pt-Com shown in reaction formula (RB-2) means a platinum compound.

In the reaction (RB-1), an aldehyde derivative represented by the general formula (XVIA) (hereinafter referred to as an aldehyde derivative (XVIA)) and a diamine (from 0.5 molar equivalent to the aldehyde derivative (XVIA)) Specifically, a compound represented by general formula (XIII) (hereinafter referred to as compound (XIII)) is obtained by heating the compound represented by general formula (XIB) in a solvent. The reaction temperature of reaction (RB-1) is, for example, 20°C or more and 100°C or less. The reaction time of reaction (RB-1) is, for example, 1 hour or more and 48 hours or less. The solvent used in reaction (RB-1) is not particularly limited, but includes, for example, methanol, ethanol, a mixture of DMF and methanol, and DMSO.

In reaction (RB-2), compound (XIII) and a platinum compound are reacted in a solvent in the presence of a base to obtain platinum complex (II). Examples of platinum compounds include PtCl ₂ (CH ₃ CN) ₂ and K ₂ PtCl ₄ . Bases include, for example, K ₂ CO ₃ , NaH and triethylamine. The reaction temperature of reaction (RB-2) is, for example, 20°C or higher and 130°C or lower. The reaction time of reaction (RB-2) is, for example, 1 hour or more and 48 hours or less. The solvent used in reaction (RB-2) is not particularly limited, but includes, for example, a mixture of DMF and methanol, DMSO, and a mixture of toluene and DMSO.

Platinum complex (III) is synthesized, for example, according to reaction formulas (RC-1) and (RC-2) below, or by a method analogous thereto. Hereinafter, the reactions represented by reaction formulas (RC-1) and (RC-2) may be referred to as reactions (RC-1) and (RC-2), respectively. Note that R 13 ^{and c in general formulas (XB), (XIVA), and (XV) shown in reaction formula (RC-1) have the same meanings as R 13 and} c in general formula (III), respectively. . Furthermore, Pt-Com shown in reaction formula (RC-2) means a platinum compound.

In reaction (RC-1), an aldehyde derivative represented by the general formula (XB) (hereinafter referred to as aldehyde derivative (XB)) and an amine (more specifically, 1 molar equivalent of the aldehyde derivative (XB)) , a compound represented by general formula (XIVA)) in a solvent to obtain a compound represented by general formula (XV) (hereinafter referred to as compound (XV)). The reaction temperature of reaction (RC-1) is, for example, 20°C or more and 100°C or less. The reaction time of reaction (RC-1) is, for example, 1 hour or more and 48 hours or less. The solvent used in reaction (RC-1) is not particularly limited, and examples thereof include methanol, ethanol, a mixture of DMF and methanol, and DMSO.

In reaction (RC-2), compound (XV) and a platinum compound are reacted in a solvent in the presence of a base to obtain platinum complex (III). Examples of platinum compounds include PtCl ₂ (CH ₃ CN) ₂ and K ₂ PtCl ₄ . Bases include, for example, K ₂ CO ₃ , NaH and triethylamine. The reaction temperature of reaction (RC-2) is, for example, 20°C or more and 130°C or less. The reaction time of reaction (RC-2) is, for example, 1 hour or more and 48 hours or less. The solvent used in reaction (RC-2) is not particularly limited, but includes, for example, a mixture of DMF and methanol, DMSO, and a mixture of toluene and DMSO.

Platinum complex (IV) is synthesized, for example, according to reaction formulas (RD-1) and (RD-2) below, or by a method analogous thereto. Hereinafter, the reactions represented by reaction formulas (RD-1) and (RD-2) may be referred to as reactions (RD-1) and (RD-2), respectively. In addition, R ^{14 and d in general formulas (XVIB), (XIVB) and (XVI) shown in reaction formula (RD-1) have the same meaning as R 14 and} d in general formula (IV), respectively. . Furthermore, Pt-Com shown in reaction formula (RD-2) means a platinum compound.

In reaction (RD-1), an aldehyde derivative represented by the general formula (XVIB) (hereinafter referred to as an aldehyde derivative (XVIB)) and an amine (more specifically, 1 molar equivalent of the aldehyde derivative (XVIB)) , a compound represented by general formula (XIVB)) in a solvent to obtain a compound represented by general formula (XVI) (hereinafter referred to as compound (XVI)). The reaction temperature of reaction (RD-1) is, for example, 20°C or more and 100°C or less. The reaction time of reaction (RD-1) is, for example, 1 hour or more and 48 hours or less. The solvent used in reaction (RD-1) is not particularly limited, but includes, for example, methanol, ethanol, a mixture of DMF and methanol, and DMSO.

In reaction (RD-2), compound (XVI) and a platinum compound are reacted in a solvent in the presence of a base to obtain platinum complex (IV). Examples of platinum compounds include PtCl ₂ (CH ₃ CN) ₂ and K ₂ PtCl ₄ . Bases include, for example, K ₂ CO ₃ , NaH and triethylamine. The reaction temperature of reaction (RD-2) is, for example, 20°C or more and 130°C or less. The reaction time of reaction (RD-2) is, for example, 1 hour or more and 48 hours or less. The solvent used in reaction (RD-2) is not particularly limited, but includes, for example, a mixture of DMF and methanol, DMSO, and a mixture of toluene and DMSO.

[Configuration of organic EL element]
Next, the configuration of the organic EL element according to this embodiment will be explained.

(Layer structure)
The layer structure of the organic EL element according to this embodiment is not particularly limited as long as it has a layer structure including an anode, a cathode, and a light emitting layer provided between the anode and the cathode. Examples of the layer structure of the organic EL element according to this embodiment include layer structures C1 to C7 shown below.

C1: Anode/Emissive layer/Cathode C2: Anode/Emissive layer/Electron transport layer/Cathode C3: Anode/Hole transport layer/Emissive layer/Cathode C4: Anode/Hole transport layer/Emissive layer/Electron transport layer/Cathode C5: Anode/Hole transport layer/Emissive layer/Electron transport layer/Electron injection layer (Cathode buffer layer)/Cathode C6: Anode/Hole injection layer (Anode buffer layer)/Hole transport layer/Emissive layer/Electron transport Layer/Cathode C7: Anode/Hole injection layer (Anode buffer layer)/Hole transport layer/Light emitting layer/Electron transport layer/Electron injection layer (Cathode buffer layer)/Cathode

Furthermore, the organic EL element according to this embodiment may have a substrate that supports an anode or a cathode. When the organic EL element according to this embodiment has a substrate, the organic EL element according to this embodiment may be a top emission type that takes out light to the side opposite to the substrate, or a bottom emission type that takes out light to the side of the substrate. It may be a type.

Hereinafter, as an example of the organic EL element according to the present embodiment, a bottom emission type organic EL element having a C7 layer structure and a substrate supporting an anode will be described with reference to the drawings. FIG. 1 to be referred to is a cross-sectional view showing an example of the structure of an organic EL element according to this embodiment. In addition, in order to make it easier to understand, the reference FIG. 1 mainly shows each component schematically, and the size, number, shape, etc. of each component shown in the diagram are changed for convenience of drawing. It may differ from the actual situation.

The organic EL element 10 shown in FIG. 1 includes a substrate 11, an anode 12, a hole injection layer 13, a hole transport layer 14, a light emitting layer 15, an electron transport layer 16, an electron injection layer 17, and a cathode 18. The anode 12, hole injection layer 13, hole transport layer 14, light emitting layer 15, electron transport layer 16, electron injection layer 17, and cathode 18 are stacked on the substrate 11 in this order.

The thickness of the substrate 11 is, for example, 0.1 mm or more and 30 mm or less, preferably 0.5 mm or more and 5 mm or less. The thickness of the anode 12 is, for example, 10 nm or more and 1000 nm or less, preferably 30 nm or more and 200 nm or less. The thickness of the hole injection layer 13 is, for example, 1 nm or more and 1000 nm or less, preferably 5 nm or more and 50 nm or less. The thickness of the hole transport layer 14 is, for example, 10 nm or more and 150 nm or less, preferably 20 nm or more and 100 nm or less. The thickness of the light emitting layer 15 is, for example, 3 nm or more and 100 nm or less, preferably 5 nm or more and 50 nm or less. The thickness of the electron transport layer 16 is, for example, 10 nm or more and 150 nm or less, preferably 20 nm or more and 100 nm or less. The thickness of the electron injection layer 17 is, for example, 0.1 nm or more and 10 nm or less, preferably 0.5 nm or more and 5 nm or less. The thickness of the cathode 18 is, for example, 10 nm or more and 500 nm or less, preferably 50 nm or more and 200 nm or less.

The organic EL element 10 has, for example, an anode 12, a hole injection layer 13, a hole transport layer 14, a light emitting layer 15, an electron transport layer 16, an electron injection layer 17, and a cathode 18 stacked in this order on a substrate 11. It can be obtained by The lamination method for laminating each layer on the substrate 11 is not particularly limited, and may be, for example, a known lamination method (more specifically, a sputtering method, a spin coating method, a vacuum evaporation method, etc.) depending on the material constituting each layer. , printing method, etc.) can be adopted.

Next, suitable materials constituting each layer of the organic EL element 10 will be explained.

(Substrate 11)
Since the organic EL element 10 is a bottom emission type organic EL element, the material of the substrate 11 is preferably a highly transparent material (transparent material). Transparent materials suitable for the substrate 11 include, for example, glass materials and resin materials. Examples of the glass material include quartz glass and soda glass. Examples of the resin material include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and polyarylate. Only one type of material may be used for the substrate 11, or two or more types may be used in combination.

(Anode 12)
The anode 12 injects holes into the hole injection layer 13 . Therefore, as the material for the anode 12, a material with a relatively large work function is used. Further, since the organic EL element 10 is a bottom emission type organic EL element, the material of the anode 12 is preferably a highly transparent material. Examples of suitable materials for the anode 12 (materials with a relatively large work function and high transparency) include tin-doped indium oxide (hereinafter sometimes referred to as ITO) and fluorine-doped indium oxide (hereinafter sometimes referred to as ITO). Examples include tin oxide. Only one type of material for the anode 12 may be used, or two or more types may be used in combination. In order to further increase luminous efficiency, ITO is preferable as the material for the anode 12.

(Hole injection layer 13)
As a material for the hole injection layer 13, for example, a composite consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) (hereinafter sometimes referred to as PEDOT-PSS) is used. ), copper phthalocyanine, and poly(3,4-ethylenedioxythiophene). Only one type of material for the hole injection layer 13 may be used, or two or more types may be used in combination. In order to further increase the luminous efficiency, PEDOT-PSS is preferable as the material for the hole injection layer 13.

(Hole transport layer 14)
Examples of materials for the hole transport layer 14 include aromatic amine derivatives, polyvinylcarbazole, polyvinylcarbazole derivatives, polysilane, polysilane derivatives, polysiloxane derivatives, pyrazoline derivatives, stilbene derivatives, polyaniline, polyaniline derivatives, polythiophene, polythiophene derivatives, and polypyrrole. , and polypyrrole derivatives. Only one type of material for the hole transport layer 14 may be used, or two or more types may be used in combination. In order to further increase luminous efficiency, the material for the hole transport layer 14 is preferably an aromatic amine derivative, such as N,N'-di-1-naphthyl-N,N'-diphenylbenzidine (hereinafter referred to as NPB). ) is more preferable.

(Light emitting layer 15)
The light emitting layer 15 contains the above-mentioned specific platinum complex. Furthermore, the light emitting layer 15 may contain a host compound in addition to the specific platinum complex. In order to further increase the luminous efficiency, it is preferable that the luminescent layer 15 contains a specific platinum complex and a host compound, and the luminescent layer 15 is composed of a specific platinum complex and a host compound (composed only of a specific platinum complex and a host compound). It is more preferable that Note that when the light-emitting layer 15 contains a host compound, the light-emitting layer 15 may contain only one type of host compound, or may contain two or more types of host compounds.

Further, the light emitting layer 15 may be made of a specific platinum complex. When the light-emitting layer 15 is composed of a specific platinum complex (composed only of a specific platinum complex), co-evaporation is not required when forming the light-emitting layer 15, for example. Therefore, in order to further improve the productivity of the organic EL element 10, it is preferable that the light emitting layer 15 is made of a specific platinum complex.

When the light-emitting layer 15 contains a host compound, in order to further increase the light-emitting efficiency, the concentration of the specific platinum complex in the light-emitting layer 15 should be 1% by mass or more and 80% by mass or less based on the total mass of the light-emitting layer 15. It is preferably at least 5% by mass and at most 50% by mass, and even more preferably at least 5% by mass and at most 35% by mass.

When the light-emitting layer 15 contains a host compound, in order to further increase the light-emitting efficiency, the host compound contained in the light-emitting layer 15 may be 4,4'-bis(9H-carbazol-9-yl)biphenyl (hereinafter referred to as CBP), 1,3-bis(9-carbazolyl)benzene, 4,4'-bis(carbazol-9-yl)-2,2'-dimethylbiphenyl, polyvinylcarbazole, polyphenylene and polyfluorene One or more types selected from the group consisting of are preferred, and CBP is more preferred.

(Electron transport layer 16)
The material for the electron transport layer 16 is, for example, 2,2',2''-(1,3,5-benzentriyl)tris(1-phenyl-1H-benzimidazole) (hereinafter referred to as TPBi). 2-phenyl-4,6-bis(3,5-dipyridylphenyl)pyrimidine, pyrazine derivatives, and phenanthroline derivatives. Only one type of material for the electron transport layer 16 may be used, or two or more types may be used in combination. In order to further increase luminous efficiency, TPBi is preferable as the material for the electron transport layer 16.

(Electron injection layer 17)
Examples of materials for the electron injection layer 17 include lithium fluoride, magnesium fluoride, and aluminum oxide. Only one type of material may be used for the electron injection layer 17, or two or more types may be used in combination. In order to further increase luminous efficiency, lithium fluoride is preferable as the material for the electron injection layer 17.

(Cathode 18)
Cathode 18 injects electrons into electron injection layer 17 . Therefore, as the material for the cathode 18, a material with a relatively small work function is used. Examples of the material for the cathode 18 include aluminum, silver, magnesium, calcium, and gold. Only one type of material for the cathode 18 may be used, or two or more types may be used in combination. In order to further increase luminous efficiency, aluminum is preferable as the material for the cathode 18.

Although the organic EL device 10 (organic EL device having a C7 layer structure) according to the present embodiment has been described above with reference to FIG. 1, the present invention is limited to the organic EL device 10 shown in FIG. It's not a thing.

For example, the organic EL device of the present invention may have any of the layer configurations of C1 to C6 described above. When any of the layer configurations C1 to C6 is adopted as the layer configuration of the organic EL element of the present invention, the material of each layer constituting the organic EL element is, for example, the material of the layer with the same name in the organic EL element 10. Materials exemplified as can be used.

Further, the organic EL element of the present invention may have a layer structure different from the layer structure of C1 to C7 described above, as long as it has a layer structure including an anode, a cathode, and a light emitting layer provided between the anode and the cathode. may have.

Further, in the organic EL device of the present invention, the material other than the specific platinum complex used as the material for the light emitting layer is not particularly limited. Therefore, the materials other than the specific platinum complex in the organic EL element of the present invention may be different from the materials exemplified as the materials constituting the organic EL element 10.

Examples of the present invention will be described below, but the present invention is not limited to the scope of the examples in any way. The nuclear magnetic resonance spectrum ( ¹ H-NMR spectrum) of the platinum complex was measured using a nuclear magnetic resonance apparatus (“UNITY-INOVA” manufactured by Varian, resonance frequency: 500 MHz). In measuring the ¹ H-NMR spectrum of the platinum complex, the residual signal of the measurement solvent (CDCl ₃ ) was used as an internal standard. In addition, the solid-state luminescence quantum yield φ of the platinum complex was measured using a spectrofluorometer (“FP-6500N” manufactured by JASCO Corporation) and an integrating sphere unit (“INK-533” manufactured by JASCO Corporation). did.

In addition, the molecular structures of Compound (1), Compound (3), Compound (4), Compound (5), and Compound (6) obtained by the synthesis method described below are all obtained by imaging plate single crystal automatic X-ray This was confirmed by single crystal X-ray structural analysis using a Mo-Kα ray (λ=0.71075 Å) using a structure analyzer (“PAPID-AUTO” manufactured by Rigaku Co., Ltd.).

<Synthesis of platinum complex>
[Synthesis of compound (1)]
Compound (1) was synthesized according to reaction formulas (R1-1) and (R1-2) below. Hereinafter, the reactions represented by reaction formulas (R1-1) and (R1-2) may be referred to as reactions (R1-1) and (R1-2), respectively.

In reaction (R1-1), pyrazole-3-carbaldehyde (0.480 g, 5.0 mmol) and 1,12-dodecanediamine (0.501 g, 2.5 mmol) were added to ethanol (50 mL), The resulting mixture was heated to reflux (reflux time: 20 hours). Thereafter, the solvent (ethanol) was removed from the reaction solution under reduced pressure, and the ligand N,N'-(dodecane-1,12-diyl)bis[1-(1H-pyrazol-5-yl)methanimine] (hereinafter sometimes referred to as ligand 1-1) was obtained as a yellow liquid. The obtained ligand 1-1 was used in the next reaction (R1-2) without purification.

In reaction (R1-2), under argon atmosphere, ligand 1-1 (0.891 g, 2.5 mmol), PtCl ₂ (CH ₃ CN) ₂ (0.870 g, 2.5 mmol) and K ₂ CO ₃ (4.146 g, 30.0 mmol) was heated in a mixed solvent of toluene (300 mL) and DMSO (75 mL) at a temperature of 120° C. for 24 hours. Thereafter, toluene was removed from the reaction solution under reduced pressure, and the precipitated solid was separated by filtration (solid-liquid separation). The separated solid was then dissolved in ethyl acetate (400 mL). Next, the obtained solution was washed three times with saturated saline (200 mL), and then the organic layer was separated from the washed solution. Then, the separated organic layer was dried with Na ₂ SO ₄ and then the dried organic layer was filtered. Then, the obtained filtrate was concentrated under reduced pressure to obtain a crude product. Next, the obtained crude product was subjected to silica gel column chromatography (filling material: amino-modified silica gel) using CH ₂ Cl ₂ /hexane (volume ratio: CH ₂ Cl ₂ /hexane = 3/7) as a developing solvent. Compound (1) was obtained as a yellow solid (yield: 0.345 g, yield: 25%). The chemical shift value δ (unit: ppm) of the ¹ H-NMR spectrum of the obtained compound (1) is shown below.

Compound (1): ¹ H-NMR (500 MHz, CDCl ₃ ) δ=0.93-1.05 (m, 2H), 1.12-1.41 (m, 14H), 1.55-1.65 (m, 2H), 2.20-2.31 (m, 2H), 3.39 (ddd, J=11.1, 11.1, 3.0Hz, 2H), 5.34 (dddd, J= 11.1, 4.7, 3.9, 1.1Hz, 2H), 6.62 (d, J = 2.1Hz, 2H), 7.68 (d, J = 2.1Hz, 2H), 7 .84 (s, 2H).

[Synthesis of compound (3)]
Compound (3) was synthesized according to reaction formulas (R3-1) and (R3-2) below. Hereinafter, the reactions represented by reaction formulas (R3-1) and (R3-2) may be referred to as reactions (R3-1) and (R3-2), respectively.

In reaction (R3-1), pyrazole-3-carbaldehyde (0.480 g, 5.0 mmol) and pentylamine (0.436 g, 5.0 mmol) were added to ethanol (30 mL), and the resulting mixture was heated to reflux (reflux time: 24 hours). Thereafter, the solvent (ethanol) was removed from the reaction solution under reduced pressure, and the ligand N-pentyl-1-(1H-pyrazol-5-yl)methanimine (hereinafter referred to as ligand 3-1) was removed. ) was obtained as a yellow liquid. The obtained ligand 3-1 was used in the next reaction (R3-2) without purification.

In reaction (R3-2), under argon atmosphere, ligand 3-1 (0.360 g, 2.0 mmol), PtCl ₂ (CH ₃ CN) ₂ (0.348 g, 1.0 mmol) and K ₂ CO ₃ (1.658 g, 12.0 mmol) was heated in a mixed solvent of toluene (120 mL) and DMSO (30 mL) at a temperature of 120° C. for 24 hours. Thereafter, toluene was removed from the reaction solution under reduced pressure, and the precipitated solid was separated by filtration (solid-liquid separation). The separated solid was then dissolved in ethyl acetate (200 mL). Next, the obtained solution was washed three times with saturated saline (200 mL), and then the organic layer was separated from the washed solution. Then, the separated organic layer was dried with Na ₂ SO ₄ and then the dried organic layer was filtered. Then, the obtained filtrate was concentrated under reduced pressure to obtain a crude product. Next, the obtained crude product was subjected to silica gel column chromatography (filling material: amino-modified silica gel) using CH ₂ Cl ₂ /hexane (volume ratio: CH ₂ Cl ₂ /hexane = 2/3) as a developing solvent. Compound (3) was obtained as an orange solid (yield: 0.330 g, yield: 63%). The chemical shift value δ (unit: ppm) of the ¹ H-NMR spectrum of the obtained compound (3) is shown below.

Compound (3): ¹ H-NMR (500 MHz, CDCl ₃ ) δ=0.90 (t, J=7.0 Hz, 6H), 1.32-1.43 (m, 8H), 1.78-1 .86 (m, 4H), 4.26 (t, J=7.0Hz, 4H), 6.57 (d, J=2.1Hz, 2H), 7.65 (d, J=2.1Hz, 2H), 7.70(s, 2H).

[Synthesis of compound (4)]
Compound (4) was synthesized according to reaction formulas (R4-1) and (R4-2) below. Hereinafter, the reactions represented by reaction formulas (R4-1) and (R4-2) may be referred to as reactions (R4-1) and (R4-2), respectively.

In reaction (R4-1), pyrazole-3-carbaldehyde (0.380 g, 4.0 mmol) and hexadecaneamine (0.970 g, 4.0 mmol) were added to ethanol (50 mL), and the resulting mixture was heated to reflux (reflux time: 24 hours). Thereafter, the solvent (ethanol) was removed from the reaction solution under reduced pressure, and the ligand N-hexadecane-1-(1H-pyrazol-5-yl)methanimine (hereinafter referred to as ligand 4-1) was removed. ) was obtained as a yellow liquid. The obtained ligand 4-1 was used in the next reaction (R4-2) without purification.

In reaction (R4-2), under argon atmosphere, ligand 4-1 (1.280 g, 4.0 mmol), PtCl ₂ (CH ₃ CN) ₂ (0.700 g, 2.0 mmol) and K ₂ CO ₃ (3.320 g, 24.0 mmol) was heated in a mixed solvent of toluene (400 mL) and DMSO (100 mL) at a temperature of 120° C. for 24 hours. Thereafter, toluene was removed from the reaction solution under reduced pressure, and the precipitated solid was separated by filtration (solid-liquid separation). The separated solid was then dissolved in ethyl acetate (150 mL). Next, the obtained solution was washed three times with saturated saline (200 mL), and then the organic layer was separated from the washed solution. Then, the separated organic layer was dried with Na ₂ SO ₄ and then the dried organic layer was filtered. Then, the obtained filtrate was concentrated under reduced pressure to obtain a crude product. Next, the obtained crude product was subjected to silica gel column chromatography (filling material: amino-modified silica gel) using CH ₂ Cl ₂ /hexane (volume ratio: CH ₂ Cl ₂ /hexane = 2/8) as a developing solvent. By purification, compound (4) was obtained as an orange solid (yield: 0.270 g, yield: 21%). The chemical shift value δ (unit: ppm) of the ¹ H-NMR spectrum of the obtained compound (4) is shown below.

Compound (4): ¹ H-NMR (500 MHz, CDCl ₃ ) δ = 0.89 (t, 6H), 1.20-1.36 (m, 48H), 1.36-1.44 (m, 4H) ), 1.81-1.90 (m, 4H), 4.37 (t, 4H), 6.62 (d, 2H), 7.66 (d, 2H), 7.87 (s, 2H) ．．

[Synthesis of comparative compounds]
As comparison compounds, a compound represented by the following chemical formula (5) (hereinafter sometimes referred to as compound (5)) and a compound represented by the following chemical formula (6) (hereinafter referred to as compound (6)) ) were synthesized.

Compound (5) was prepared using the following formula (5.0 mmol) instead of pyrazole-3-carbaldehyde (5.0 mmol) when synthesizing the ligand. It was synthesized in the same manner as compound (1). In addition, compound (6) was obtained by using a compound represented by the following chemical formula (6A) (5.0 mmol) instead of pyrazole-3-carbaldehyde (5.0 mmol) when synthesizing the ligand. was synthesized in the same manner as compound (1).

<Measurement of solid-state luminescence quantum yield φ>
After recrystallizing the obtained Compound (1), Compound (3), Compound (4), Compound (5) and Compound (6), each of the obtained crystals was treated at a temperature of 298K and a temperature of 77K. The solid-state luminescence quantum yield φ (unit: %) was measured. As the recrystallization solvent during recrystallization, chloroform was used for compound (3), and toluene was used for compound (1), compound (4), compound (5), and compound (6).

The solid-state luminescence quantum yield φ was measured by the absolute method using light with a wavelength of 420 nm as excitation light. In addition, in order to eliminate the influence of oxygen during measurement, the samples (crystals of compound (1), crystals of compound (3), crystals of compound (4), crystals of compound (5), and crystals of compound (6)) Either) was placed in a quartz cell, argon gas was passed through the quartz cell for 1 minute, and then measurements were taken under an argon gas atmosphere. Further, in the measurement at a temperature of 77 K, the quartz cell containing the crystal was cooled with liquid nitrogen using a quartz Dewar cooler. The emission spectrum obtained in the measurement was corrected by using a standard light source. A solid-state quantum efficiency calculation program (manufactured by JASCO Corporation) was used to calculate the solid-state luminescence quantum yield φ. In addition, the maximum wavelength of light emitted by the sample (any of the crystals of compound (1), crystals of compound (3), crystals of compound (4), crystals of compound (5), and crystals of compound (6)) The emission maximum wavelength) was also measured. Table 1 shows the results of solid-state luminescence quantum yield φ and solid-state luminescence maximum wavelength.

As shown in Table 1, Compound (1), Compound (3), and Compound (4) have a higher solid-state luminescence quantum yield at a temperature of 298 K (room temperature) than Compound (5) and Compound (6), which are comparative compounds. φ was high. These results showed that Compound (1), Compound (3), and Compound (4) are suitable for organic EL devices that are solid-state light emitting devices.

<Production of organic EL element>
As organic EL devices of Examples, organic EL devices D-1 to D-3 were produced using compound (1) obtained by the above-mentioned synthesis method. The method for manufacturing organic EL elements D-1 to D-3 will be described below. In addition, in the following description, "vapor deposition rate" is the thickness of a film formed per unit time (film formation rate).

[Production of organic EL element D-1]
First, the following materials were prepared.

Transparent base material D-1a: A transparent base material in which a film (anode) made of ITO is formed with a thickness of 150 nm by sputtering on a glass substrate (thickness: 0.7 mm) Coating liquid D for hole injection layer -1b: PEDOT-PSS (“Baytron P Al4083” manufactured by Bayer)
Material for hole transport layer D-1c: NPB
Phosphorescent material D-1d: Compound (1)
Host compound D-1e: CBP
Material for electron transport layer D-1f: TPBi
Material for electron injection layer D-1g: Lithium fluoride Material for cathode D-1h: Aluminum

The prepared transparent substrate D-1a was ultrasonically cleaned in acetone for 10 minutes and then in 2-propanol for 10 minutes. Next, the ultrasonically cleaned transparent substrate D-1a was boiled in 2-propanol for 5 minutes, dried with nitrogen gas, and then UV ozone cleaned.

Next, the hole injection layer coating liquid D-1b was applied by spin coating onto the anode of the transparent substrate D-1a that had been cleaned with UV ozone. The coating conditions for the spin coating method were a rotation speed of 5000 rpm and a rotation time of 40 seconds. Next, the applied hole injection layer coating liquid D-1b was heated at a temperature of 120° C. for 20 minutes to form a hole injection layer (thickness: 20 nm) on the anode.

Next, material D-1c for hole transport layer was deposited on the hole injection layer by vacuum evaporation method (degree of vacuum: 1 × 10 ^-4 Pa) to obtain a hole transport layer (thickness: 30 nm). Ta. The deposition rate when depositing the hole transport layer material D-1c was 1.5 Å/sec.

Next, the phosphorescent material D-1d and the host compound D-1e are co-evaporated onto the hole transport layer by a vacuum evaporation method (degree of vacuum: 1×10 ^-4 Pa) to form the phosphorescent material D. A light-emitting layer (thickness: 15 nm, concentration of phosphorescent material D-1d in the light-emitting layer: 20% by mass based on the total mass of the light-emitting layer) was obtained. The deposition rate of the phosphorescent material D-1d when co-evaporating the phosphorescent material D-1d and the host compound D-1e was 0.4 Å/sec. Further, the vapor deposition rate of the host compound D-1e when co-evaporating the phosphorescent material D-1d and the host compound D-1e was 1.6 Å/sec. Note that the above-mentioned vapor deposition rates of the phosphorescent material D-1d and the host compound D-1e are values converted to the vapor deposition rates when both are vapor-deposited alone.

Next, electron transport layer material D-1f was deposited on the light emitting layer by a vacuum deposition method (degree of vacuum: 1×10 ^-4 Pa) to obtain an electron transport layer (thickness: 50 nm). The deposition rate when depositing the electron transport layer material D-1f was 2.0 Å/sec.

Next, electron injection layer material D-1g was deposited on the electron transport layer by a vacuum evaporation method (degree of vacuum: 1 × 10 ^-4 Pa) to obtain an electron injection layer (thickness: 0.8 nm). . The deposition rate for depositing electron injection layer material D-1g was 0.1 Å/sec.

Next, cathode material D-1h was deposited on the electron injection layer by vacuum evaporation (degree of vacuum: 1×10 ^-4 Pa) to obtain a cathode (thickness: 100 nm). The deposition rate when depositing the cathode material D-1h was 8.0 Å/sec. Through the above steps, organic EL element D-1 was obtained.

[Production of organic EL element D-2]
Organic EL element D-2 was obtained by the same method as for producing organic EL element D-1, except that the method for forming the light emitting layer was changed to the method shown below.

(Method for forming light emitting layer of organic EL element D-2)
A phosphorescent material D-1d is deposited on the hole transport layer by a vacuum evaporation method (degree of vacuum: 1×10 ^-4 Pa) to form a layer composed of the phosphorescent material D-1d (phosphorescent material D). A light-emitting layer (thickness: 10 nm) consisting only of -1d was obtained. The deposition rate when depositing the phosphorescent material D-1d was 2.0 Å/sec.

[Production of organic EL element D-3]
Organic EL element D-3 was obtained by the same method as for producing organic EL element D-1, except that the method for forming the light emitting layer was changed to the method shown below.

(Method for forming light emitting layer of organic EL element D-3)
A phosphorescent material D-1d is deposited on the hole transport layer by a vacuum evaporation method (degree of vacuum: 1×10 ^-4 Pa) to form a layer composed of the phosphorescent material D-1d (phosphorescent material D). A light-emitting layer (thickness: 30 nm) consisting only of -1d was obtained. The deposition rate when depositing the phosphorescent material D-1d was 2.0 Å/sec.

<Evaluation method>
The evaluation method for organic EL elements D-1 to D-3 will be explained below. Note that all the evaluations described below were performed at room temperature (298K).

[Current density]
Using a DC voltage/current source (“Model 2400” manufactured by Keithley Instruments), the current density was measured when a DC voltage was applied to each of the organic EL elements D-1 to D-3. The results are shown in Figure 2. As shown in FIG. 2, in the voltage range of 6 V or more and 8 V or less, organic EL elements D-2 and D-3 that do not contain a host compound in their light emitting layer are different from organic EL elements D that contains a host compound in their light emitting layer. The current density was higher than -1.

[Emission spectrum]
The emission spectra when a voltage of 7 V was applied to each of organic EL elements D-1 to D-3 using a DC voltage/current source (Model 2400 manufactured by Keithley Instruments) were measured using a spectroradiometer (Model 2400 manufactured by Keithley Instruments). It was measured using "SR-3" manufactured by Topcon. The results are shown in Figure 3. Note that the normalized luminescence intensity on the vertical axis in FIG. 3 is normalized by dividing the luminescence intensity for each wavelength measured in the wavelength range of 450 nm or more and 750 nm or less by the maximum luminescence intensity in the wavelength range of 450 nm or more and 750 nm or less. Means luminescence intensity. As shown in FIG. 3, the peak positions of the emission spectra of the organic EL elements D-1 to D-3 were the same. In addition, a sample (hereinafter referred to as sample TF) in which a thin film (thickness: 60 nm) made of compound (1) was provided on a glass substrate was prepared separately, and when the thin film was irradiated with excitation light with a wavelength of 400 nm. The emission spectrum of was measured using an ultraviolet/visible spectrophotometer ("MCPD-3700" manufactured by Otsuka Electronics Co., Ltd.). The peak position of the measured emission spectrum (not shown) of sample TF coincided with the peak position of the emission spectrum of organic EL elements D-1 to D-3.

[Luminance and external quantum efficiency]
The brightness when voltage was applied to each of organic EL elements D-1 to D-3 using a DC voltage/current source (Model 2400 manufactured by Keithley Instruments) was measured using a luminance meter (Model 2400 manufactured by Keithley Instruments Inc.). The current density-voltage-luminance characteristics were evaluated by measuring using the LS-110''. In addition, the emission spectra when a voltage was applied to each of organic EL elements D-1 to D-3 using a DC voltage/current source (Model 2400 manufactured by Keithley Instruments) were measured using a luminance meter (Konica Minolta, Inc.). Measurement was carried out using the company's "LS-110"). Based on the obtained current density-voltage-luminance characteristics and emission spectra, the external quantum efficiencies of organic EL elements D-1 to D-3 were calculated by a luminance conversion method. The results are shown in FIGS. 4 and 5. FIG. 4 is a graph showing the relationship between voltage and brightness in organic EL elements D-1 to D-3. Further, FIG. 5 is a graph showing the relationship between current density and external quantum efficiency in organic EL elements D-1 to D-3.

As shown in FIG. 4, in the voltage range of 6 V or more and 8 V or less, organic EL elements D-2 and D-3 that do not contain a host compound in their light emitting layer are different from organic EL elements D that contains a host compound in their light emitting layer. The brightness was higher than -1.

As shown in FIG. 5, in organic EL elements D-2 and D-3, an external quantum efficiency of about 0.4% was obtained even if the host compound was not contained in the light emitting layer. Further, in organic EL element D-1 containing a host compound in the light emitting layer, an external quantum efficiency of about 2.0% was obtained.

The above results indicate that the present invention can provide an organic EL device with high luminous efficiency (that is, an organic EL device with high productivity) regardless of the concentration of the specific platinum complex in the light emitting layer.

The organic EL device according to the present invention is useful as an organic EL device with high productivity.

10: Organic EL element (organic electroluminescent element)
12: Anode 15: Luminescent layer 18: Cathode

Claims (5)

An organic electroluminescent device comprising an anode, a cathode, and a light emitting layer provided between the anode and the cathode,
The light-emitting layer is an organic electroluminescent device in which the light-emitting layer contains only a platinum complex represented by the following general formula (I), the following general formula (II), the following general formula (III), or the following general formula (IV).

(In the general formula (I), the general formula (II), the general formula (III) and the general formula (IV),
n1 and n2 are each independently an integer of 2 or more and 20 or less,
R ¹ and R ² each independently represent a halogen atom, an alkyl group having 1 to 32 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkynyl group having 2 to 16 carbon atoms, and a carbon atom. Cycloalkyl group having 5 to 8 carbon atoms, alkoxy group having 1 to 16 carbon atoms, amino group, alkylamino group having 1 to 16 carbon atoms, hydroxy group, carboxy group, having 2 to 17 carbon atoms an alkoxycarbonyl group, phenyl group, phenoxy group, nitrile group, nitro group or thiol group,
R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a halogen atom, an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, and 2 to 16 carbon atoms. Alkynyl group, cycloalkyl group having 5 to 8 carbon atoms, alkoxy group having 1 to 16 carbon atoms, amino group, alkylamino group having 1 to 16 carbon atoms, hydroxy group, carboxy group, carbon atom an alkoxycarbonyl group, phenyl group, phenoxy group, nitrile group, nitro group or thiol group having a number of 2 or more and 17 or less,
a and c are each independently an integer of 0 or more and 2 or less,
b and d are each independently an integer of 0 or more and 4 or less. ) The organic electrolyte according to claim 1, wherein a, b, c and d are 0 in the general formula (I), the general formula (II), the general formula (III) and the general formula (IV). Luminescence element. The organic electroluminescent device according to claim 1 or 2, wherein the light emitting layer contains a platinum complex represented by the general formula (I) or the general formula (II). The light-emitting layer includes a platinum complex represented by the general formula (III) or the general formula (IV),
The organic electrolyte according to claim 1 or 2, wherein in the general formula (III) and the general formula (IV), R ¹ and R ² are each independently an alkyl group having 1 to 32 carbon atoms. Luminescence element. The organic electroluminescent device according to claim 1, wherein the light emitting layer contains a platinum complex represented by the following chemical formula (1).

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