The disclosure of Japanese Patent Application No. 2021-131972 filed Aug. 13, 2021 is expressly incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to an organic electroluminescence device, an electronic device, and a compound.

BACKGROUND ART

An organic electroluminescence device (hereinafter, occasionally referred to as “organic EL device”) has found its application in a full-color display for mobile phones, televisions and the like. When a voltage is applied to an organic EL device, holes and electrons are injected from an anode and a cathode, respectively, into an emitting layer. The injected holes and electrons are recombined in the emitting layer to form excitons. Specifically, according to the electron spin statistics theory, singlet excitons and triplet excitons are generated at a ratio of 25%:75%.

In order to improve performance of an organic EL device, studies on laminating a plurality of emitting layers have been made, for instance, in Literature 1 (JP 2019-161218 A) and Literature 2 (International Publication No. WO2021/049662). In addition, Literature 3 (International Publication No. WO2010/134350) describes a phenomenon where singlet excitons are generated by collision and fusion of two triplet excitons (hereinafter, occasionally referred to as a Triplet-Triplet Fusion (TTF) phenomenon) in order to improve performance of an organic EL device.

The performance of the organic EL device is evaluatable in terms of, for instance, luminance, emission wavelength, chromaticity, emission efficiency, drive voltage, and lifetime.

SUMMARY OF THE INVENTION

An object of the invention is to provide an organic electroluminescence device having a low drive voltage and high luminous efficiency, a compound capable of decreasing a drive voltage to improve luminous efficiency of an organic electroluminescence device, and an electronic device including the organic electroluminescence device.

According to an aspect of the invention, there is provided an organic electroluminescence device including: an anode; a cathode; and an emitting region provided between the anode and the cathode, in which the emitting region includes a first emitting layer and a second emitting layer, a ratio DEM1/DEM2of a film thickness of the first emitting layer DEM1to a film thickness of the second emitting layer DEM2is in a range from 2/3 to 3/2, the first emitting layer contains a first host material and a first emitting compound, the second emitting layer contains a second host material and a second emitting compound, the first host material is a compound represented by a formula (1) below, the first host material is different from the second host material, and the first emitting compound and the second emitting compound are mutually the same or different.



In the formula (1):

R1Aand R1Bare each independently a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms;

at least one of R1Aor R1Bis a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms;

one combination of a combination of adjacent two or more of R11to R14and a combination of adjacent two or more of R15to R18are mutually bonded to form a substituted or unsubstituted monocyclic ring, or mutually bonded to form a substituted or unsubstituted fused ring;

when the substituted or unsubstituted monocyclic ring or the substituted or unsubstituted fused ring is formed with a ring A, a group represented by a formula (10) is bonded to a carbon atom bonded to R12or a carbon atom, among carbon atoms forming the substituted or unsubstituted monocyclic ring or the substituted or unsubstituted fused ring, at a position farthest from a carbon atom C1of the ring A bonded by a single bond to a carbon atom C2of a ring B;

when the substituted or unsubstituted monocyclic ring or the substituted or unsubstituted fused ring is formed not with the ring A but with the ring B, the group represented by the formula (10) is bonded to the carbon atom bonded to R12; and

R12not bonded with the group represented by the formula (10), and R11, R13, R14and R15to R18not forming the substituted or unsubstituted monocyclic ring and not forming the substituted or unsubstituted fused ring are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted haloalkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a group represented by —Si(R901)(R902)(R903), a group represented by —O—(R904), a group represented by —S—(R905), a group represented by —N(R906)(R907), a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, a group represented by —C(═O)R801, a group represented by —COOR802, a halogen atom, a cyano group, a nitro group, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms.

In the formula (10):

Ar1is a substituted or unsubstituted aryl group having four or more fused rings, or a substituted or unsubstituted heterocyclic group having four or more fused rings;

L1is a single bond, a substituted or unsubstituted arylene group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted divalent heterocyclic group having 5 to 17 ring atoms;

mx is 0, 1, or 2;

* represents a bonding position to an atom forming a ring of the formula (1); and

the first host material does not contain, in a molecule of the first host material, three or more of: a substituted or unsubstituted aryl group having four or more fused rings; and a substituted or unsubstituted heterocyclic group having four or more fused rings.

In the first host material:

R901, R902, R903, R904, R905, R906, R907, R801and R802are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms;

when a plurality of R901are present, the plurality of R901are mutually the same or different;

when a plurality of R902are present, the plurality of R902are mutually the same or different;

when a plurality of R903are present, the plurality of R903are mutually the same or different;

when a plurality of R904are present, the plurality of R904are mutually the same or different;

when a plurality of R905are present, the plurality of R905are mutually the same or different;

when a plurality of R906are present, the plurality of R906are mutually the same or different;

when a plurality of R907are present, the plurality of R907are mutually the same or different;

when a plurality of R801are present, the plurality of R801are mutually the same or different; and

when a plurality of R802are present, the plurality of R802are mutually the same or different.

According to another aspect of the invention, there is provided a compound represented by a formula (1A) below.



In the formula (1A):

R1Aand R1Bare each independently a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms;

at least one of R1Aor R1Bis a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms;

at least one combination of a combination of R11and R12, a combination of R12and R13, a combination of R16and R17, and a combination of R17and R18, are mutually bonded to form a substituted or unsubstituted monocyclic ring, or mutually bonded to form a substituted or unsubstituted fused ring;

when the combination of R11and R12or the combination of R12and R13are mutually bonded to form a substituted or unsubstituted monocyclic ring or a substituted or unsubstituted fused ring with a ring A, a group represented by the formula (10A) is bonded to a carbon atom, among carbon atoms forming the substituted or unsubstituted monocyclic ring or the substituted or unsubstituted fused ring, at a position farthest from a carbon atom C1of the ring A bonded by a single bond to a carbon atom C2of a ring B;

R12not forming the substituted or unsubstituted monocyclic ring and not forming the substituted or unsubstituted fused ring is the group represented by the formula (10A); and

R11, R13, R14and R15to R1, not forming the substituted or unsubstituted monocyclic ring and not forming the substituted or unsubstituted fused ring are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted haloalkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a group represented by —Si(R901)(R902)(R903), a group represented by —O—(R904), a group represented by —S—(R905), a group represented by —N(R906)(R907), a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, a group represented by —C(═O)R801, a group represented by —COOR802, a halogen atom, a cyano group, a nitro group, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms.

In the formula (10A):

Ar1is a substituted or unsubstituted aryl group having four or more fused rings, or a substituted or unsubstituted heterocyclic group having four or more fused rings;

L1is a single bond, a substituted or unsubstituted arylene group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted divalent heterocyclic group having 5 to 17 ring atoms;

mx is 0, 1, or 2;

* represents a bonding position to an atom forming a ring of the formula (1A); and

the compound represented by the formula (1A) does not contain, in a molecule of the compound, three or more of: a substituted or unsubstituted aryl group having four or more fused rings; and a substituted or unsubstituted heterocyclic group having four or more fused rings.

In the compound represented by the formula (1A):

R901, R902, R903, R904, R905, R906, R907, R801and R802are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms;

when a plurality of R901are present, the plurality of R901are mutually the same or different;

when a plurality of R902are present, the plurality of R902are mutually the same or different;

when a plurality of R903are present, the plurality of R903are mutually the same or different;

when a plurality of R904are present, the plurality of R904are mutually the same or different;

when a plurality of R905are present, the plurality of R905are mutually the same or different;

when a plurality of R906are present, the plurality of R906are mutually the same or different;

when a plurality of R907are present, the plurality of R907are mutually the same or different;

when a plurality of R801are present, the plurality of R801are mutually the same or different; and

when a plurality of R802are present, the plurality of R802are mutually the same or different.

According to still another aspect of the invention, there is provided a compound represented by a formula (1B) below.



In the formula (1B):

R1Aand R1Bare each independently a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms;

at least one of R1Aor R1Bis a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms;

one combination of a combination of adjacent two or more of R11to R14and a combination of adjacent two or more of R15to R18are mutually bonded to form a substituted or unsubstituted monocyclic ring, or mutually bonded to form a substituted or unsubstituted fused ring;

when the substituted or unsubstituted monocyclic ring or the substituted or unsubstituted fused ring is formed with a ring A, a group represented by a formula (10B) is bonded to a carbon atom bonded to R12or a carbon atom, among carbon atoms forming the substituted or unsubstituted monocyclic ring or the substituted or unsubstituted fused ring, at a position farthest from a carbon atom C1of the ring A bonded by a single bond to a carbon atom C2of a ring B;

when the substituted or unsubstituted monocyclic ring or the substituted or unsubstituted fused ring is formed not with the ring A but with the ring B, the group represented by the formula (10B) is bonded to the carbon atom bonded to R12; and

R12not bonded with the group represented by the formula (10B), and R11, R13, R14and R15to R18not forming the substituted or unsubstituted monocyclic ring and not forming the substituted or unsubstituted fused ring are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted haloalkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a group represented by —Si(R901)(R902)(R903), a group represented by —O—(R904), a group represented by —S—(R905), a group represented by —N(R906)(R907), a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, a group represented by —C(═O)R801, a group represented by —COOR802, a halogen atom, a cyano group, a nitro group, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms.

In the formula (10B):

Ar1is a substituted or unsubstituted aryl group having four or more fused rings, or a substituted or unsubstituted heterocyclic group having four or more fused rings;

Ar1is not a substituted or unsubstituted pyrenyl group;

L1is a single bond, a substituted or unsubstituted arylene group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted divalent heterocyclic group having 5 to 17 ring atoms;

mx is 0, 1, or 2;

* represents a bonding position to an atom forming a ring of the formula (1B); and

the compound represented by the formula (1B) does not contain, in a molecule of the compound, three or more of: a substituted or unsubstituted aryl group having four or more fused rings; and a substituted or unsubstituted heterocyclic group having four or more fused rings.

In the compound represented by the formula (1B):

R901, R902, R903, R904, R905, R906, R907, R801and R802are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 17 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 17 ring atoms;

when a plurality of R901are present, the plurality of R901are mutually the same or different;

when a plurality of R902are present, the plurality of R902are mutually the same or different;

when a plurality of R903are present, the plurality of R903are mutually the same or different;

when a plurality of R904are present, the plurality of R904are mutually the same or different;

when a plurality of R905are present, the plurality of R905are mutually the same or different;

when a plurality of R906are present, the plurality of R906are mutually the same or different;

when a plurality of R907are present, the plurality of R907are mutually the same or different;

when a plurality of R801are present, the plurality of R801are mutually the same or different; and

when a plurality of R802are present, the plurality of R802are mutually the same or different.

According to a further aspect of the invention, there is provided an electronic device including the organic electroluminescence device according to the above aspect of the invention.

According to a still further aspect of the invention, there are provided an organic electroluminescence device having a low drive voltage and high luminous efficiency, a compound capable of decreasing a drive voltage to improve luminous efficiency of an organic electroluminescence device, and an electronic device including the organic electroluminescence device.

