CN111987228A - Blue light organic electroluminescent device - Google Patents

Abstract

The present invention relates to an organic electroluminescent device comprising a light-emitting layer B comprising two host materials, namely an n-type (electron transporting) and a p-type (hole transporting) host material, a Thermally Activated Delayed Fluorescence (TADF) material and an emitter material which exhibits a narrow deep blue emission with a small FWHM with an emission maximum of 440 to 475 nm. The invention further relates to a method for producing blue light by means of the organic electroluminescent device according to the invention.

Description

Blue light organic electroluminescent device

The present invention relates to organic electroluminescent devices comprising a light-emitting layer B comprising two host materials, namely an n-type (electron transport) and a p-type (hole transport) host material, a Thermally Activated Delayed Fluorescence (TADF) material, and an emitter material. The emitter material produces a narrow (i.e., small full width at half maximum FWHM) deep blue light emitting at a maximum of 440 to 475 nm. The invention further relates to a method for producing blue light by means of the inventive organic electroluminescent device.

Description of the invention

Organic electroluminescent devices comprising one or more organic based light emitting layers, such as Organic Light Emitting Diodes (OLEDs), light emitting electrochemical cells (LECs) and light emitting transistors, are of increasing importance. In particular, OLEDs are promising devices for electronic products, such as screens, displays and lighting devices. Organic electroluminescent devices based on organic matter are generally quite flexible and can be produced in particularly thin layers, compared to most electroluminescent devices based on substantially inorganic matter. There are screens and display appliances based on OLEDs which present particularly good vivid colors, contrast and also have considerable efficiency in terms of energy consumption.

A core element of an organic electroluminescent device for generating light is a light emitting layer interposed between an anode and a cathode. When a voltage (and a current) is applied to the organic electroluminescent device, holes and electrons are injected from the anode and the cathode, respectively, to the light emitting layer. Typically, a hole transport layer is located between the light-emitting layer and the anode, and an electron transport layer is located between the light-emitting layer and the cathode. The layers are placed in sequence. The recombination of the holes and electrons then generates high-energy excitons. Decay of such excited states (e.g., such as the S1 singlet and/or the T1 triplet) to the ground state (S0) desirably results in light emission.

In order to achieve efficient energy transport and excitation, organic electroluminescent devices comprise one or more host compounds and one or more emitter compounds as dopants. Therefore, challenges in producing organic electroluminescent devices are how to increase the luminance (i.e., luminance per unit current) of the devices, obtain a desired spectrum, and achieve a desired lifetime.

There is still a need for efficient and stable OLEDs emitting in the deep blue region of the visible spectrum, which have small CIEy values. Therefore, there is still an unmet technical need for organic electroluminescent devices with long lifetime and high quantum yield, especially in the deep blue range.

Exciton-polaron interactions (triplet-polaron and singlet-polaron interactions) and exciton-exciton interactions (singlet-singlet, triplet-singlet and triplet-triplet interactions) are the major pathways for device aging. Degradation pathways such as triplet-triplet annihilation (TTA) and triplet-polaron quenching (TPQ) are particularly important for deep blue emitting devices because they produce high energy states. In particular, charged emitter molecules tend to generate energetic excitons and/or polarons. For the separation of polarons and/or excitons so-called hybrid-host systems are used, but this approach is limited because of the lack of a stable n-type host material, which has the lowest triplet state and insufficient energy to quench the excitons at the emitter.

Another interesting parameter is the activation energy emitted by the emitter, represented by the energy of S1. If the Bond Dissociation Energy (BDE) of the weakest bond is exceeded, high energy photons, particularly in combination with other polarons or excited states, may lead to degradation of the organic material. Therefore, the S1 energy of the emitter (the main component contributing to the emission) should be as low as possible, so for deep blue emitting OLEDs it is desirable to employ an emitter with a smaller FWHM. Furthermore, other materials, such as host materials, should not contribute to the emission, as the S1 energy of the host needs to be higher than the energy of the emitter to avoid quenching. Therefore, efficient energy transfer is required from all materials within the light emitting layer to the emitter material.

When the organic electroluminescent device comprises two host materials (TADF material and small FWHM emitter material), an efficient separation of excitons and polarons can be achieved.

Surprisingly, it has been found in the present invention that an emission layer of an organic electroluminescent device comprising two host materials, i.e. an n-type electron transporting and a p-type hole transporting host material, a Thermally Activated Delayed Fluorescence (TADF) material and an emitter material, which exhibits a narrow deep blue emission, i.e. a small full width half maximum FWHM, can provide an organic electroluminescent device having a good lifetime and quantum yield and exhibiting deep blue emission. Here, the main emission of the device originates from small FWHM emitter materials, which are in particular close range charge transfer (NRCT) emitters. Surprisingly, the energy transfer within the device is sufficient to produce a deep blue emission with a small FWHM and therefore a low CIEy color coordinate.

Accordingly, one aspect of the present invention relates to an organic electroluminescent device comprising a light-emitting layer B comprising:

(i) host material H^NHaving the lowest excited singlet energy level S1^NLowest excited triplet energy level T1^NContaining energy of E^HOMO(H^N) Highest occupied molecular orbital HOMO (H)^N) And contains energy of E ^LUMO(H^N) Lowest unoccupied molecular orbital LUMO (H)^N)；

(ii) Host material H^PHaving the lowest excited singlet energy level S1^PAnd a lowest excited triplet energy level T1^PContaining energy of E^HOMO(H^P) Highest occupied molecular orbital HOMO (H)^P) And an energy content of E^LUMO(H^P) Lowest unoccupied fraction ofSub-orbital LUMO (H)^P)；

(iii) Thermally Activated Delayed Fluorescence (TADF) Material E^BHaving the lowest excited singlet energy level S1^EAnd a lowest excited triplet energy level T1^EHaving an energy of E^HOMO(E^E) Highest occupied molecular orbital HOMO (E)^E) And has an energy of E^LUMO(E^E) Lowest unoccupied molecular orbital LUMO (E)^E) (ii) a And

(iv) small FWHM transmitter S^BHaving the lowest excited singlet energy level S1^SAnd a lowest excited triplet energy level T1^SHaving an energy of E^HOMO(E^S) Highest occupied molecular orbital HOMO (E)^S) And has an energy of E^LUMO(E^S) Lowest unoccupied molecular orbital LUMO (E)^S) In which S is^BMaximum lambda max of the emitted light^PMMA(S) has a value of 440nm to 475nm,

wherein a relationship represented by the following formulas (1) to (3) and a relationship represented by at least one of (4a) or (4b) are satisfied:

S1^N>S1^E (1)

S1^P>S1^E (2)

E^LUMO(H^N)-E^HOMO(H^P)>S1^E (3)

E^LUMO(H^P)-E^LUMO(H^N)≥0.2eV (4a)

E^HOMO(H^P)-E^HOMO(H^N)≥0.2eV (4b)，

and satisfies the relationships represented by the following formulas (5) to (8):

S1^N>S1^S (5)

S1^P>S1^S (6)

S1^E>S1^S (7)

S1^S<2.95eV (8)。

according to the invention, the host material H^BIs higher than that of Thermally Activated Delayed Fluorescence (TADF) material E^BThe lowest excited singlet state.Host material H ^NIs higher than the energy of TADF material E^BThe lowest excited singlet state. Host material H^NIs larger than the energy difference between the Lowest Unoccupied Molecular Orbital (LUMO) of the host material HP and the Highest Occupied Molecular Orbital (HOMO) of the host material HP, is larger than that of the Thermally Activated Delayed Fluorescence (TADF) material E^BThe lowest energy to excite the singlet state.

Host material H^PIs at least 0.20eV higher than the HOMO of the host material HN, i.e. E^HOMO(H^P) Ratio E^HOMO(H^N) The negativity is at least 0.20eV lower. H^NLUMO and H of^PMust be greater than H^NHOMO and H of^PIs different between HOMO's (i.e. E)^LUMO(H^N)-E^HOMO(H^P)>E^HOMO(H^P)-E^HOMO(H^N)). In a preferred embodiment, host material H^PHOMO ratio host material H^NIs higher than 0.20eV, preferably higher than 0.25eV or more preferably higher than 0.30 eV. In general, the host material H^PHOMO ratio host material H^NIs less than 4.0eV, more preferably less than 3.0eV, even more preferably less than 2.0eV or even less than 1.0 eV.

Alternatively, the Lowest Unoccupied Molecular Orbital (LUMO) energy of the host material HP is at least 0.20eV higher than the LUMO of the host material HN, i.e., E^LUMO(H^P) Ratio E^LUMO(H^N) The negativity is at least 0.20eV lower. H^NLUMO and H of^PMust be greater than H^NThe difference between the LUMO of (A) and the LUMO of (B) (i.e. E) ^LUMO(H^N)-E^HOMO(H^P)>E^LUMO(H^P)-E^LUMO(H^N)). In a preferred embodiment, the LUMO of the host material HP is higher than the LUMO of the host material HN by a value greater than 0.20eV, more preferably greater than 0.25eV or even more preferably greater than 0.30 eV. Generally, the LUMO of the host material HP is greater than that of the host material H^NBy an energy of less than 4.0eV, more preferably less than 3.0eV, even more preferably less than 2.0eV or even less than 1.0 eV.

Host material H^BIs higher than the lowest excited singlet state of the small FWHM emitter SB. Host material H^NHas an energy higher than S in the lowest excited singlet state^BThe lowest excited singlet state. TADF Material E^BHas an energy higher than S in the lowest excited singlet state^BThe lowest excited singlet state. S^BOf the lowest excited singlet state, i.e. S^BIs less than 2.95eV, preferably less than 2.90eV, more preferably less than 2.85eV, even more preferably less than 2.80eV or even less than 2.75 eV.

It was surprisingly found that the main contribution of the emission band of the optoelectronic device of the invention originates from S^BIndicates emission from E^BTo S^BAnd from the host material H^PAnd H^NTo E^BAnd/or S^BThe energy transfer of (2) is sufficient.

In one embodiment, host material H^PHighest Occupied Molecular Orbital (HOMO) energy ratio host material H ^NIs higher by at least 0.20eV, and the Lowest Unoccupied Molecular Orbital (LUMO) of the host material HP is at a higher energy than the host material H^NIs at least 0.20eV higher. In a preferred embodiment, host material H^PHOMO energy ratio host material H^NIs higher by a value greater than 0.20eV, more preferably greater than 0.25eV or even more preferably greater than 0.30eV, and host material H^PRelative LUMO to host material H^NBy a value greater than 0.20eV, more preferably greater than 0.25eV or even more preferably greater than 0.30 eV.

In one embodiment, H^PAnd H^NAn exciplex (exiplex) is formed. The person skilled in the art knows how to select a pair of H^PAnd H^NTo form exciplex and knowing the selection criteria-in addition to the above-mentioned HOMO-and/or LUMO-level requirements-for example H^PAnd H^NLow spatial shielding (low steric shielding).

In one embodiment, HN is selected from the group or a mixture of two or more selected from the group consisting of:

in one embodiment, H^PSelected from the group consisting of:

in one embodiment, H^PAnd H^NForming an exciplex; h^PAnd S^BNo exciplex formation; h^NAnd S^BDoes not form an exciplex, E^BAnd S ^BNo exciplex is formed.

In one embodiment, H^PAnd H^NForming an exciplex; h^PAnd E^BNo exciplex formation; h^NAnd E^BNo exciplex formation; h^PAnd S^BNo exciplex formation; h^NAnd S^BDoes not form an exciplex, E^BAnd S^BNo exciplex is formed.

H^PAnd E^B；H^NAnd E^B；H^PAnd S^B；H^NAnd S^B(ii) a Or E^BAnd S^BFormation of exciplex

In one embodiment, H^NFree of any phosphine oxide groups, in particular H^NIs not bis [2- (diphenylphosphino) phenyl ]]Ether oxide (bis [2- (diphenylphosphino) phenyl)]ether oxide，DPEPO)。

As used herein, the terms "TADF material" and "TADF emitter" are interchangeable in meaning.

According to the invention, the TADF material is characterised in that it exhibits a Delta E_STValue corresponding to the lowest excited singlet state (S1)) And the lowest excited triplet state (T1), which is less than 0.4eV, preferably less than 0.3eV, more preferably less than 0.2eV, even more preferably less than 0.1eV or even less than 0.05 eV. Preferred methods for determining T1 and S1 are described herein.

As used herein, the terms organic electroluminescent device and optoelectronic light-emitting device may be understood in the broadest sense as any device comprising a light-emitting layer B comprising two host materials H ^PAnd H^NTADF Material E^BAnd small FWHM transmitter S^B。

An organic electroluminescent device may be understood in the broadest sense as any device based on organic materials which is adapted to emit light in the visible or most recently Ultraviolet (UV) range, i.e. in the wavelength range 380-800 nm. More preferably, the organic electroluminescent device may emit light in the visible light range, i.e., 400 to 800 nm.

Selecting a small FWHM transmitter S^BSuch that it exhibits a full width at half maximum (FWHM) emission energy in Polymethylmethacrylate (PMMA) of less than 0.35eV, preferably less than 0.30eV, more preferably less than 0.25eV, even more preferably less than 0.20 or even less than 0.15 eV. The value is λ max^PMMAI.e. the value measured in PMMA with 10% by weight of emitter (here the emitter means the small FWHM emitter S)^BWherein wt.% is relative to the total content of PMMA and emitter).

In a preferred embodiment, the organic electroluminescent device refers to an Organic Light Emitting Diode (OLED), a light emitting electrochemical cell (LEC) or a light emitting transistor.

Particularly preferably, the organic electroluminescent device is an Organic Light Emitting Diode (OLED). Optionally, the organic electroluminescent device as a whole may be opaque, translucent or substantially transparent.

The term "layer" as used in the context of the present invention is preferably a body having a geometrical planar shape.

The thickness of the light-emitting layer B is preferably not more than 1mm, more preferably not more than 0.1mm, even more preferably not more than 10 μm, even more preferably not more than 1 μm, and particularly not more than 0.1 μm.

In a preferred embodiment, the Thermally Activated Delayed Fluorescence (TADF) material EB is an organic TADF material. According to the invention, organic light emitters or organic materials mean that the light emitter or material consists essentially of the elements hydrogen (H), carbon (C), nitrogen (N), boron (B), silicon (Si) and optionally fluorine (F), optionally bromine (Br) and optionally oxygen (O). Particularly preferably, it does not contain any transition metals.

In a preferred embodiment, the TADF material E^BIs an organic TADF material. In a preferred embodiment, the small FWHM transmitter S^BIs an organic emitter. In a more preferred embodiment, the TADF material E^BAnd a small FWHM transmitter S^BAre all organic materials.

In a particularly preferred embodiment, at least one TADF material E^BIs a blue, preferably a deep blue TADF material.

Compound H^PAnd H^NAnd a luminous body E^BAnd S^BMay be included in the organic electroluminescent device in any amount and in any ratio.

In a preferred embodiment, in the organic electroluminescent device of the invention, the compound H in the light-emitting layer B is present on a weight basis^PIs greater than the amount of illuminant E^BThe amount of (c).

In a preferred embodiment, in the organic electroluminescent device of the invention, the compound H in the light-emitting layer B is present on a weight basis^NIs greater than the amount of illuminant E^BThe amount of (c).

In a preferred embodiment, in the organic electroluminescent device of the present invention, TADF material E is contained in the light-emitting layer B on a weight basis^BIs greater than the emitter S^BThe amount of (c).

In a preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B includes:

(i) 10-84% by weight of a host compound H^P；

(ii) 10-84% by weight of a host compound H^N；

(iii) 5-50% by weight of TADF Material E^B(ii) a And

(iv) 1-10% by weight of a luminophore S^B(ii) a And optionally

(v)0-74 wt% of one or more solvents.

In another preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B includes:

(i) 10-30% by weight of a host compound H^P；

(ii) 40-74% by weight of host compound H^N；

(iii) 15-30% by weight of TADF Material E^B(ii) a And

(iv) 1-5% by weight of a luminophore S^B(ii) a And optionally

(v)0-34 wt% of one or more solvents.

In a preferred embodiment, the TADF material EB exhibits an emission maximum (i.e. λ max) measured in polymethyl methacrylate (PMMA)^PMMA(E^B) In the range of 440-470 nm. In a preferred embodiment, TADF Material E^BExhibits an emission maximum value λ max in the range of 445 to 465nm^PMMA(E^B)。

Small FWHM emitter S^BDevices being organic blue fluorescent emitters

In one embodiment of the invention, the small FWHM emitter S^BAre organic blue fluorescent emitters.

In one embodiment, the small FWHM emitter S^BIs an organic blue fluorescent emitter selected from the group consisting of:

in certain embodiments, the small FWHM emitter S^BIs an organic blue fluorescent emitter selected from the group consisting of:

small FWHM emitter S^BDevice for triplet-triplet annihilation (TTA) fluorescence emitters

In one embodiment of the invention, a small FWHM transmitter S^BIs a blue organic triplet-triplet annihilation (TTA) emitter. In one embodiment, the small FWHM transmitter S^BIs a blue organic TTA emitter selected from the group consisting of:

small FWHM transmitter S^BDevice being a short range charge transfer (NRCT) emitter

In one embodiment of the invention, a small FWHM transmitter S^BIs a near field charge transfer (NRCT) emitter. As described in Hatakeyama et al, journal of "advanced materials", NRCT emitters exhibit a delayed component in the time-resolved photoluminescence spectrum and exhibit short-range HOMO-LUMO separation. (Advanced Materials, 2016,28 (14): 2777-. In some embodiments, the NRCT emitter is a TADF material. In one embodiment, the small FWHM emitter SB is a blue boron containing NRCT emitter.

In a preferred embodiment, the small FWHM illuminant S^BComprising or consisting of polycyclic aromatic compounds.

In a preferred embodiment, the small FWHM illuminant S^BComprising (or consisting of) polycyclic aromatic compounds according to formula (1) or (2) or specific examples described in US 2015/236274 a. US 2015/236274a also describes examples of the synthesis of these compounds.

In one embodiment, the small FWHM transmitter S^BComprising (or consisting of) a structure according to formula 1 or:

wherein the content of the first and second substances,

n is 0 or 1.

m＝1-n。

X¹Is N or B.

X²Is N or B.

X³Is N or B.

W is selected from Si (R)³)₂,C(R³)₂And BR³。

R¹，R²And R³Each independently of the others selected from:

C₁-C₅-alkyl, optionally substituted with one or more substituents R⁶Substitution;

C₆-C₆₀-aryl, optionally substituted with one or more substituents R⁶Substitution; and

C₃-C₅₇-heteroaryl, optionally substituted with one or more substituents R⁶Substitution;

R^I，R^II，R^III，R^IV，R^V，R^VI，R^VII，R^VIII，R^IX，R^Xand R^XIEach independently selected from the group consisting of: hydrogen, deuterium, N (R)⁵)₂,OR⁵,Si(R⁵)₃,B(OR⁵)₂,OSO₂R⁵,CF₃CN, halogen, C₁-C₄₀-alkyl (optionally substituted with one or more substituents R)⁵Substituted, and in which one or more non-adjacent CH₂Each of the radicals is optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵O, S or CONR⁵Substituted);

C₁-C₄₀alkoxy (which is optionally substituted by one or more substituents R)⁵Substituted, and wherein one or more non-adjacent CH ₂Each of the radicals is optionally substituted by R⁵C＝CR⁵,C≡C,Si(R5)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵,O,S or CONR⁵Substitution;

C₁-C₄₀thioalkoxy (which is optionally substituted with one or more substituents R5, and wherein one or more non-adjacent CH' s₂Each of the radicals is optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵,O,S or CONR⁵Substitution;

C₂-C₄₀alkenyl (which is optionally substituted with one or more substituents R5, and wherein one or more non-adjacent CH' s₂Each of the radicals is optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵,O,S or CONR⁵And (4) substitution.

C₂-C₄₀-alkynyl (which is optionally substituted with one or more substituents R5, and wherein one or more non-adjacent CH's are₂Each of the radicals is optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵,O,S or CONR⁵Substitution;

C₆-C₆₀aryl (which is optionally substituted by one or more substituents R)⁵Substituted); and C₃-C₅₇Heteroaryl (which is optionally substituted by one or more substituents R)⁵Substitution).

R⁵Independently at each occurrence, selected from the group consisting of: hydrogen, deuterium, OPh, CF₃，CN，F，C₁-C₅-alkyl (in which one or more hydrogen atoms are optionally independently from each other deuterium, CN, CF)₃Or F substituted); c₁-C₅Alkoxy (in which one or more hydrogen atoms are optionally independently from each other deuterium, CN, CF)₃Or F substituted);

C₁-C₅thioalkoxy (in which one or more hydrogen atoms are optionally independently of each other deuterium, CN, CF)₃Or F substituted);

C₂-C₅alkenyl (in which one or more hydrogen atoms are optionally independently from each other deuterium, CN, CF)₃Or F substituted);

C₂-C₅alkynyl (in which one or more hydrogen atoms are optionally independently from each other deuterium, CN, CF) ₃Or F substituted);

C₆-C₁₈aryl (optionally substituted by one or more C)₁-C₅-alkyl substituent substitution);

C₃-C₁₇heteroaryl (optionally substituted by one or more C)₁-C₅-alkyl substituent substitution);

N(C₆-C₁₈an aryl group) 2 selected from the group consisting of,

N(C₃-C₁₇heteroaryl group)₂(ii) a And

N(C₃-C₁₇heteroaryl) (C₆-C₁₈Aryl).

R⁶Independently at each occurrence is selected from hydrogen, deuterium, OPh, CF₃，CN，F，C₁-C₅-alkyl (in which one or more hydrogen atoms are optionally independently from each other deuterium, CN, CF)₃Or F substituted);

C₁-C₅alkoxy (in which one or more hydrogen atoms are optionally independently from each other deuterium, CN, CF)₃Or F substituted);

C₁-C₅thioalkoxy (in which one or more hydrogen atoms are optionally independently of each other deuterium, CN, CF)₃Or F substituted);

C2-C5 alkenyl (in which one or more hydrogen atoms are optionally independently from each other deuterium, CN, CF)₃Or F substituted);

C₂-C₅alkynyl (in which one or more hydrogen atoms are optionally independently from each other deuterium, CN, CF)₃Or F substituted);

C₆-C₁₈-aryl, optionally substituted by one or more C₁-C₅-alkyl substituent substitution;

C₃-C₁₇-heteroaryl, optionally substituted by one or more C₁-C₅-alkyl substituent substitution;

N(C₆-C₁₈an aryl group) 2 selected from the group consisting of,

N(C₃-C₁₇heteroaryl group)₂(ii) a And

N(C₃-C₁₇heteroaryl) (C₆-C₁₈Aryl).

According to a preferred embodiment, two or more are selected from

R^I，R^II，R^III，RIV，R^V，R^VI，R^VII，R^VIII，R^IX，R^XAnd R^XIAdjacent to each other and together form a mono-or polycyclic ring system, which ring system is an aliphatic, aromatic and/or benzo-fused ring system.

According to a preferred embodiment, X¹，X²And X³Is B, and X¹，X²And X³Is N.

According to a preferred embodiment of the invention, at least one is selected from

R^I，R^II，R^III，R^IV，R^V，R^VI，R^VII，R^VIII，R^IX，R^XAnd R^XIOptionally form an aliphatic, aromatic and/or benzo-fused monocyclic or polycyclic ring system with one or more adjacent substituents selected from the same group,

according to a preferred embodiment of the invention, X¹，X²And X³Is B, and X¹，X²And X³Is N.

In one embodiment, the small FWHM transmitter S^BComprising (or consisting of) a structure according to formula 1, and X¹And X³Are all N, and X²Is B:

in one embodiment, the small FWHM transmitter S^BComprising (or consisting of) a knot according to formula 1Structure and X¹And X³Are all B, and X²Is N:

in one embodiment, the small FWHM transmitter S^BA structure comprising (or consisting of) a structure according to formula 1, and n ═ 0.

In one embodiment, R¹And R²Each independently selected from the group consisting of:

C₁-C₅-alkyl, optionally substituted with one or more substituents R⁶Substitution;

C₆-C₃₀-aryl, optionally substituted with one or more substituents R⁶Substitution; and

C₃-C₃₀-heteroaryl, optionally substituted with one or more substituents R⁶And (4) substitution.

In one embodiment, R¹And R²Each independently selected from Me, iPr, tBu, CN, CF₃，

Ph (which is optionally substituted by one or more substituents independently of one another selected from Me, iPr, tBu, CN, CF₃And substituent of Ph);

pyridyl (which is optionally substituted by one or more substituents independently of one another selected from Me, iPr, tBu, CN, CF₃And substituent of Ph);

pyrimidinyl (which is optionally substituted by one or more substituents independently of one another selected from Me, iPr, tBu, CN, CF₃And substituent of Ph); and

triazinyl (which is optionally substituted by one or more substituents independently of one another selected from Me, iPr, tBu, CN, CF₃And substituent of Ph).

In one embodiment, RI, RII, RIII, RIV, RV, RVI, RVII, RVIII, RIX, RX and RXI are independently from each other selected from the group consisting of: hydrogen, deuterium, halogen, Me, iPr, tBu, CN, CF3,

ph (which is optionally substituted with one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

pyridyl (which is optionally substituted with one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

pyrimidinyl (which is optionally substituted by one or more substituents independently from each other selected from Me, iPr, tBu, CN, CF3 and Ph);

Carbazolyl (which is optionally substituted with one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

triazinyl (which is optionally substituted with one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph); and

N(Ph)2。

in one embodiment, R^I，R^II，R^III，R^IV，R^V，R^VI，R^VII，R^VIII，R^IX，R^XAnd R^XIIndependently of each other selected from the group consisting of: hydrogen, deuterium, halogen, Me, iPr, tBu, CN, CF₃，

Ph (which is optionally substituted by one or more substituents independently of one another selected from Me, iPr, tBu, CN, CF₃And substituent of Ph);

pyridyl (which is optionally substituted by one or more substituents independently of one another selected from Me, iPr, tBu, CN, CF₃And substituent of Ph);

pyrimidinyl (which is optionally substituted by one or more substituents independently of one another selected from Me, iPr, tBu, CN, CF₃And substituent of Ph);

carbazolyl (optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF)₃And substituent of Ph);

triazinyl (which is optionally substituted by one or more substituents independently of one another selected from Me, iPr, tBu, CN, CF₃And substituent of Ph); and

N(Ph)₂；

and R¹And R²Each independently selected from the group consisting of:

C₁-C₅-alkyl, any of whichOptionally substituted by one or more substituents R⁶Substitution;

C₆-C₃₀-aryl, optionally substituted with one or more substituents R ⁶Substitution; and

C₃-C₃₀-heteroaryl, optionally substituted with one or more substituents R⁶And (4) substitution.

In one embodiment, the small FWHM transmitter S^BIs a blue boron-containing NRCT emitter selected from the group consisting of:

the person skilled in the art will note that the organic electroluminescent device of the invention generally contains a light-emitting layer B. Preferably, such an organic electroluminescent device comprises at least the following layers: at least one light emitting layer B, at least one anode layer a and at least one cathode layer C.

Preferably, the anode layer a contains a component selected from the group consisting of: indium tin oxide, indium zinc oxide, PbO, SnO, graphite, doped silicon, doped germanium, doped GaAs, doped polyaniline, doped polypyrrole, doped polythiophene, and mixtures of two or more of the foregoing.

Preferably, the cathode layer C contains a component selected from the group consisting of:

al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, In, W, Pd, LiF, Ca, Ba, Mg, and mixtures and/or alloys of two or more of the foregoing.

Preferably, the light emitting layer B is located between the anode layer a and the cathode layer C. Therefore, the general arrangement is preferably A-B-C. This of course does not preclude the presence of one or more optional other layers. Other layers may be present on each side of a, B and/or C.

In a preferred embodiment, the organic electroluminescent device comprises at least the following layers:

A) an anode layer a comprising a component selected from the group consisting of: indium tin oxide, indium zinc oxide, PbO, SnO, graphite, doped silicon, doped germanium, doped GaAs, doped polyaniline, doped polypyrrole, doped polythiophene, and mixtures of two or more of the foregoing;

B) a light-emitting layer B; and

C) a cathode layer C comprising a component selected from the group consisting of:

al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, In, W, Pd, LiF, Ca, Ba, Mg, and mixtures and/or alloys of two or more of the above,

wherein the light emitting layer B is located between the anode layer a and the cathode layer C.

In one embodiment, when the organic electroluminescent device is an OLED, it may optionally comprise the following layer structure:

A) an anode layer a, illustratively comprising Indium Tin Oxide (ITO);

HTL) a hole transport layer HTL;

B) the light emitting layer B of the present invention as described herein;

ETL) electron transport layer ETL; and

C) a cathode layer, illustratively comprising Al, Ca and/or Mg.

Preferably, the order of layers herein is A-HTL-B-ETL-C.

In addition, the organic electroluminescent device may optionally include one or more protective layers to protect the device from harmful substances in the environment, including, for example, moisture, vapor, and/or gases.

Preferably, the anode layer a is located on the surface of the substrate. The substrate may be formed of any material or combination of materials. Most commonly, glass sheets are used as substrates. Alternatively, a thin metal layer (e.g., copper, gold, silver, or aluminum film) or a plastic film or sheet may be used. This allows for greater flexibility. The anode layer a consists essentially of the material of the (substantially) transparent film. One of the anode layer a and the cathode layer C is transparent, since at least one of the two electrodes should be (substantially) transparent to allow light emission of the OLED. Preferably, the anode layer a comprises a large amount or consists entirely of a Transparent Conductive Oxide (TCO).

Such anode layer a may illustratively comprise indium tin oxide, aluminum zinc oxide, fluorinated tin oxide, indium zinc oxide, PbO, SnO, zirconium oxide, molybdenum oxide, vanadium oxide, tungsten oxide, graphite, doped Si, doped Ge, doped GaAs, doped polyaniline, doped polypyrrole and/or doped polythiophene.

Particularly preferably, the anode layer a consists (substantially) of Indium Tin Oxide (ITO) (e.g., (InO3)0.9(SnO2) 0.1). The roughness of the anode layer a caused by the Transparent Conductive Oxide (TCO) can be compensated by using a Hole Injection Layer (HIL). Furthermore, the HIL may facilitate injection of quasi-charge carriers (i.e., holes) (as transport of quasi-charge carriers from the TCO to the Hole Transport Layer (HTL) is facilitated). The Hole Injection Layer (HIL) may comprise poly-3, 4-ethylenedioxythiophene (PEDOT), polystyrene sulfonate (PSS), MoO2, V2O5, CuPC or CuI, in particular a mixture of PEDOT and PSS. The Hole Injection Layer (HIL) may also prevent diffusion of metal from the anode layer a into the Hole Transport Layer (HTL). The HIL may illustratively comprise PEDOT: PSS (poly-3, 4-ethylenedioxythiophene: polystyrenesulfonate), PEDOT (poly-3, 4-ethylenedioxythiophene), mMTDATA (4,4 '-tris [ phenyl (m-tolyl) amino ] triphenylamine), spiro-TAD (2,2', 7,7 '-tetrakis (N, N-diphenylamino) -9,9' -spirobifluorene), DNTPD (N1, N1'- (biphenyl-4, 4' -diyl) bis (N1-phenyl-N4, N4-di-m-tolyl-1, 4-diamine), NPB (N, N '-nis- (1-naphthyl) -N, N' -bis-phenyl- (1,1 '-biphenyl) -4,4' -diamine), NPNPB (N, n '-diphenyl-N, N' -bis- [4- (N, N-diphenyl-amino) phenyl ] benzidine), MeO-TPD (N, N '-tetrakis (4-methoxyphenyl) -benzoic acid), HAT-CN (1,4,5,8,9, 11-hexaazatriphenylhexahydro-nitrile) and/or spiro-NSD (N, N' -diphenyl-N, N '-bis- (1-naphthyl) -9,9' -spirobifluorene-2, 7-diamine).

Adjacent to the anode layer a or the Hole Injection Layer (HIL), a Hole Transport Layer (HTL) is typically provided. Here, any hole transport compound may be used. For example, electron-rich heteroaromatic compounds such as triarylamines and/or carbazoles can be used as hole transport compounds. The HTL may reduce an energy barrier between the anode layer a and the light emitting layer B (serving as an emission layer (EML)). The Hole Transport Layer (HTL) may also be an Electron Blocking Layer (EBL). Preferably, the hole transport compound has a relatively high energy level of its triplet state T1. Illustratively, the Hole Transport Layer (HTL) may comprise a star-shaped heterocycle, such as 3- (4-carbazolyl-9-ylphenyl) amine (TCTA), poly-TPD (poly (4-butylphenyl-diphenylamine)), α -NPD (poly (4-butylphenyl-diphenylamine)), TAPC (4,4' -cyclohexyl-bis [ N, N-bis (4-methylphenyl) aniline ]), 2-TNATA (4,4', 4 ″ -tris [ 2-naphthyl (phenyl) -amino ] triphenylamine), spiro TAD, DNTPD, NPB, npnpnpb, MeO-TPD, HAT-CN and/or tricspz (9,9' -diphenyl-6- (9-phenyl-9H-carbazol-3-yl) -9H, 9'H-3,3' -carbo). In addition, the HTL may include a p-doped layer, which may be composed of inorganic or organic dopants in an organic hole-transporting matrix. Transition metal oxides such as vanadium oxide, molybdenum oxide or tungsten oxide may be exemplarily used as the inorganic dopant. Tetrafluorotetracyanoquinodimethane (F4-TCNQ), copper pentafluorobenzoate (cu (i) pFBz) or transition metal complexes may be exemplarily used as the organic dopant.

EBL may illustratively comprise mCP (1, 3-bis (carbazol-9-yl) benzene), TCTA, 2-TNATA, mCBP (3, 3-bis (9H-carbazol-9-yl) biphenyl), 9- [3- (dibenzofuran-2-yl) phenyl ] -9H-carbazole, 9- [3- (dibenzothiophene-2-yl) phenyl ] -9H-carbazole, 9- [3, 5-bis (2-dibenzofuranyl) phenyl ] -9H-carbazole, 9- [3, 5-bis (2-dibenzothiophenyl) phenyl ] -9H-carbazole, tris-Pcz, CzSi (9- (4-tert-butylphenyl) -3, 6-bis (triphenylsilyl) -9H-carbazole), 3', 5' -bis- (N-carbazolyl) - [1,1 '-biphenyl ] -2-carbonitrile (DCPBN; CAS 1918991-70-4), 3- (N-carbazolyl) -N-phenylcarbazole (NCNPC) and/or DCB (N, N' -dicarbazolyl-1, 4-dimethylbenzene).

The orbital and excited state energies can be determined by experimental methods known to those skilled in the art. Experimentally, the energy of the highest occupied molecular orbital EHOMO can be determined with an accuracy of 0.1eV by cyclic voltammetry measurements known to those skilled in the art. The energy of the lowest unoccupied molecular orbital, ELUMO, was calculated as EHOMO + Egap, where Egap was determined as follows:

for the host compound, unless otherwise stated, the film (10% by weight of the host) was used as an emission start (onset of emission) in Polymethylmethacrylate (PMMA) as Egap, which corresponds to the energy of the first excited singlet state S1. For the emitter compounds, the energy of Egap and first excited singlet S1 was determined in the same manner as described above, unless otherwise noted. For the host compound, the energy of the first excited triplet state T1 was determined from the onset of the time-gated 77K emission spectrum (onset of the time-gated emission spectrum at 77K), which typically has a 1 millisecond delay time and an integration time of 1 millisecond. The above determination was made in a Polymethylmethacrylate (PMMA) film (weight of 10% of the host) if not otherwise specified. For TADF emitter compounds, the energy of the first excited triplet T1 was determined from the onset of the time-gated 77K emission spectrum, which typically has a 1 millisecond delay time and a 1 millisecond integration time.

In the Electron Transport Layer (ETL), any electron transporter may be used. Illustratively, electron-poor compounds such as benzimidazoles, pyridines, triazoles, oxadiazoles (e.g., 1,3, 4-oxadiazoles), phosphine oxides, and sulfones may be used. Illustratively, the electron transporter ETM may also be a star-shaped heterocycle, such as 1,3, 5-tris (1-phenyl-1H-benzo [ d ] imidazol-2-yl) phenyl (TPBi). ETM may be exemplarily NBphen (2, 9-bis (naphthalen-2-yl) -4, 7-diphenyl-1, 10-phenanthroline), Alq3 (al-tris (8-hydroxyquinoline)), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphine oxide), BPyTP2(2, 7-bis (2,2 '-bipyridin-5-yl) triphenyl), Sif87 (dibenzo [ b, d ] thiophen-2-yl triphenylsilane), Sif88 (dibenzo [ b, d ] thiophen-2-yl) diphenylsilane), BmPyPhB (1, 3-bis [3, 5-bis (pyridin-3-yl) phenyl ] benzene) and/or BTB (4,4' -bis- [2- (4, 6-diphenyl-1, 3, 5-triazinyl) ] -1,1' -biphenyl). Optionally, the electron transport layer may contain a doping material, such as Liq (lithium 8-hydroxyquinoline). Optionally, a second electron transport layer may be located between the electron transport layer and the cathode layer C. The Electron Transport Layer (ETL) itself may block holes or a Hole Blocking Layer (HBL) is employed.

HBLs may illustratively comprise BCP (2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline ═ batiochuprine), BAlq (bis (8-hydroxy-2-methylquinoline) - (4-phenylphenoxy) aluminum), NBphen (2, 9-bis (naphthalen-2-yl) -4, 7-diphenyl-1, 10-phenanthroline), Alq3 (aluminum-tris (8-hydroxyquinoline)), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphine oxide), T2T (2,4, 6-tris (biphenyl-3-yl) -1,3, 5-triazine), T3T (2,4, 6-tris (triphenyl-3-yl) -1,3, 5-triazine), TST (2,4, 6-tris (9,9 '-spirobifluoren-2-yl) -1,3, 5-triazine), DTST (2, 4-diphenyl-6- (3' -triphenylsilylphenyl) -1,3, 5-triazine), DTDBF (2, 8-bis (4, 6-diphenyl-1, 3, 5-triazinyl) dibenzofuran) and/or TCB/TCP (1,3, 5-tris (N-carbazolyl) benzene/1, 3, 5-tris (carbazol) -9-yl) benzene).

A cathode layer C may be disposed adjacent to the Electron Transport Layer (ETL). Illustratively, the cathode layer C may include (or consist of) a metal (e.g., Al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, LiF, Ca, Ba, Mg, In, W, or Pd) or a metal alloy. For practical reasons the cathode layer C may also consist of a (substantially) opaque metal such as Mg, Ca or Al. Alternatively or additionally, the cathode layer C may also comprise graphite and/or Carbon Nanotubes (CNTs). Alternatively, the cathode layer C may also consist of nanoscale silver wires.

Optionally, the OLED may further comprise a protective layer between the Electron Transport Layer (ETL) D and the cathode layer C, which may be designated as an Electron Injection Layer (EIL). The layer may include lithium fluoride, cesium fluoride, silver, Liq (lithium 8-hydroxyquinoline), Li2O, BaF2, MgO, and/or NaF.

As used herein, if not more specifically defined in a particular context, the color of emitted and/or absorbed light is specified as follows:

purple: the wavelength range is more than 380-420 nm;

dark blue: a wavelength range >420-475 nm;

sky blue: the wavelength range is more than 475-500 nm;

green: the wavelength range is more than 500-560 nm;

yellow: the wavelength range is more than 560-580 nm;

orange color: the wavelength range is greater than 580-620 nm;

red: the wavelength range is >620-800 nm.

With regard to the luminophore compound, this color refers to the emission maximum λ maxPMMA of a Polymethylmethacrylate (PMMA) film with 10% by weight of luminophore. Thus, illustratively, the emission maximum λ maxPMMA of the deep blue emitter is in the range of 420 to 475nm, the emission maximum λ maxPMMA of the sky blue emitter is in the range of 475 to 500nm, the emission maximum λ maxPMMA of the green emitter is in the range of 500 to 560nm, and the emission maximum λ maxPMMA of the red emitter is in the range of 620 to 800 nm.

The emission maximum λ maxPMMA of the deep blue emitter is preferably no greater than 475nm, more preferably less than 470nm, even more preferably less than 465nm or even less than 460 nm. It is generally above 420nm, preferably above 430nm, more preferably at least 440 nm. In preferred embodiments, the device exhibits an emission maximum λ max (D) of 420 to 475nm, 430 to 470nm, 440 to 465nm or 450 to 460 nm. In a preferred embodiment, the device exhibits an emission maximum λ max (D) of 440 to 475 nm. In a preferred embodiment, the device has an emission maximum λ max (D) of 450-470 nm.

Another embodiment of the invention relates to an OLED which has an external quantum efficiency (external quantum efficiency) at 1000cd/m2 of more than 10%, more preferably more than 13%, more preferably more than 15%, even more preferably more than 18% or even more than 20% and/or shows a maximum emission value between 420nm and 500nm, preferably between 430nm and 490nm, more preferably between 440nm and 480nm, even more preferably between 450nm and 470nm, and/or shows an LT80 value at 500cd/m2 of more than 100 hours, preferably more than 200 hours, more preferably more than 400 hours, even more preferably more than 750 hours or even more than 1000 hours.

Another embodiment of the invention relates to an OLED that emits light at a specific color point. According to the invention, the OLED has a narrow emission band, i.e. a small full width at half maximum (FWHM). In a preferred embodiment, the OLED according to the invention emits light with a main emission peak having a FWHM below 0.30eV, more preferably below 0.25eV, even more preferably below 0.20eV or even below 0.18 eV.

Another aspect of the present invention relates to an OLED that emits light with CIEx and CIEy color coordinates close to CIEx (═ 0.131) and CIEy (═ 0.046), i.e., light with CIEx and CIEy color coordinates of the primary color blue defined by ITU-R bt.2020 recommendation 2020 (recommendation 2020) (CIEx ═ 0.131 and CIEy ═ 0.046), and thus is suitable for Ultra High Definition (UHD) displays, such as UHD televisions. In commercial applications, top-emitting (top electrode is transparent) devices are commonly used, whereas the test devices used in this application are typical bottom-emitting devices (bottom electrode and substrate are transparent). When changing from a bottom emitting device to a top emitting device, the CIEy color coordinates of the blue device can be reduced by a factor of up to two while CIEx remains almost unchanged (Okinaka et al, abstract of technical paper of international seminar of the institute of information display, 2015,46 (1): 312-313, DOI: 10.1002/sdtp.10480). Therefore, another aspect of the invention relates to an OLED emitting a CIEx color coordinate between 0.02 and 0.30, preferably between 0.03 and 0.25, more preferably between 0.05 and 0.20, or even more preferably between 0.08 and 0.18 or even between 0.10 and 0.15, and/or a CIEy color coordinate between 0.00 and 0.45, preferably between 0.01 and 0.30, more preferably between 0.02 and 0.20, or even more preferably between 0.03 and 0.15 or even between 0.04 and 0.10.

In the present application, the terms "aryl" and "aromatic" are to be understood in the broadest sense as any monocyclic, bicyclic or polycyclic aromatic moiety. Aryl groups, if not otherwise specified, may also be optionally substituted with one or more substituents, which are further exemplified herein. Thus, the term "arylene" refers to a divalent residue that has two binding sites to other molecular structures and thus serves as a linking structure. In the present application, the terms "heteroaryl" and "heteroaromatic" are to be understood in the broadest sense as any monocyclic, bicyclic or polycyclic heteroaromatic moiety comprising at least one heteroatom, in particular 1 to 3 heteroatoms per aromatic ring. Exemplary heteroaromatic compounds may be pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyrimidine and the like. Heteroaryl groups, if not otherwise specified, may also be optionally substituted with one or more substituents, which are further exemplified herein. Thus, the term "heteroarylene" refers to a divalent residue that has two binding sites for other molecular structures, thereby serving as a linking structure.

In the present application, the term "alkyl" is to be understood in the broadest sense as a straight-chain or branched alkyl residue. Preferred alkyl residues contain 1 to 15 carbon atoms. Illustratively, the alkyl residue can be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and the like. Alkyl groups may also be optionally substituted, if not otherwise indicated, with one or more substituents, which are further exemplified herein. Thus, the term "alkylene" refers to a divalent residue that has two binding sites with other molecular structures, thereby serving as a linking structure.

The term "substituted" as used herein, particularly in the context of aryl, arylene, heteroaryl, alkyl and the like, is to be understood in the broadest sense, if not stated otherwise. Preferably, such substitution refers to a residue selected from the group consisting of C1-C20-alkyl, C7-C19-alkylaryl and C6-C18-aryl. Thus, preferably, there are no charged moieties, more preferably no functional groups, in such substitutions.

It should be noted that hydrogen may be replaced by deuterium at each occurrence.

Any layers of the various embodiments may be positioned by any suitable method, unless otherwise specified. The layer of the present invention including the light-emitting layer B may optionally be prepared by a liquid treatment means (also referred to as "film treatment", "fluid treatment", "solution treatment", or "solvent treatment"). This means that the components of the layers are applied to the surface of the part of the device that is in the liquid state. Preferably, the layer of the present invention including the light emitting layer B may be prepared by spin-coating (spin-coating). Thin, substantially uniform layers can be obtained using this method, which is well known to those skilled in the art.

Alternatively, the layer of the invention, including the light-emitting layer B, may be prepared by other methods based on liquid processing means, such as casting (e.g. drop casting) and rolling methods, and printing methods (e.g. inkjet printing, gravure printing, blade coating). These processes may optionally be carried out in an inert atmosphere, such as in a nitrogen atmosphere.

In another preferred embodiment, the layer of the invention may be prepared by any other method known in the art, including but not limited to vacuum treatment methods known to those skilled in the art, such as thermal (co) evaporation, organic vapor deposition (OVPD) and Organic Vapor Jet Printing (OVJP).

When the layer is prepared by means of liquid treatment, the solution comprising the layer components (for the light-emitting layer B of the invention, the layer components comprise at least one host compound HB, typically at least one first TADF material EB, at least one second TADF material SB and optionally one or more further host compounds HB2) may further comprise a volatile organic solvent. Such volatile organic solvents may optionally be selected from tetrahydrofuran, dioxane, chlorobenzene, diethylene glycol diethyl ether, 2- (2-ethoxyethoxy) ethanol, γ -butyrolactone, N-methylpyrrolidone, ethoxyethanol, xylene, toluene, anisole, phenethyl alcohol, acetonitrile, tetrahydrothiophene, benzonitrile, pyridine, trihydrofuran, triarylamine, cyclohexanone, acetone, propylene carbonate, ethyl acetate, benzene and PGMEA (propylene glycol monoethyl ether acetate). Combinations of two or more solvents may also be used. After application in the liquid state, the layer may then be dried and/or hardened by any method known in the art (either at ambient conditions, at elevated temperatures (e.g., about 50 ℃ or about 60 ℃) or under reduced pressure).

Optionally, the organic electroluminescent device (e.g., OLED) may illustratively be a substantially white organic electroluminescent device or a blue organic electroluminescent device. Exemplarily, such a white organic electroluminescent device may comprise at least one (deep) blue emitter compound (e.g. TADF material EB) and one or more green and/or red emitting emitter compounds. Then, optionally, there may be energy transmission between the two or more compounds.

As a whole, the organic electroluminescent device may be formed in a thin layer having a thickness of not more than 5mm, but more than 2mm, more than 1mm, more than 0.5mm, more than 0.25mm, more than 100 μm, or more than 10 μm.

Organic electroluminescent devices (e.g., OLEDs) can be small-sized (e.g., having a surface no greater than 5mm2, or even no greater than 1mm 2), medium-sized (e.g., a surface in the range of 0.5 to 20cm2), or large-sized (e.g., a surface greater than 20cm 2). The organic electroluminescent device according to the invention (e.g. OLED) may optionally be used to produce screens as large area lighting devices, light emitting wallpaper, light emitting window frames or panes, light emitting labels, light emitting devices or flexible screens or displays. In addition to common uses, organic electroluminescent devices (e.g., OLEDs) are illustratively used as luminescent films, "smart packaging" labels, or innovative design elements. In addition, they can be used for cell detection and examination (e.g., as biomarkers).

One of the main purposes of organic electroluminescent devices is to generate light. The invention therefore also relates to a method for producing light of a desired wavelength range, comprising the step of producing any of the organic electroluminescent devices of the invention.

Accordingly, another aspect of the invention relates to a method for generating light of a desired wavelength range, comprising the steps of:

(i) producing the organic electroluminescent device of the present invention; and

(ii) applying a current to the organic electroluminescent device.

Another aspect of the present invention relates to a method for producing an organic electroluminescent device by assembling the above elements. The invention also relates to a method for producing blue, green, yellow, orange, red or white light, in particular blue or white light, by using said organic electroluminescent device.

The following examples and claims further illustrate the invention.

Examples of the present invention

Cyclic voltammetry

Measured at a concentration of 10^-3Cyclic voltammograms (Cyclic voltammograms) of a solution of mol/l of an organic molecule in dichloromethane (or a suitable solvent) and a suitable supporting electrolyte (for example 0.1mol/l tetrabutylammonium hexafluorophosphate). The measurement was carried out at room temperature under a nitrogen atmosphere with a three-electrode assembly (working electrode and counter electrode: Pt wire, reference electrode: Pt wire) and FeCp was used ₂/FeCp₂ ⁺As an internal standard. The HOMO data was corrected using ferrocene as an internal standard against SCE.

Theoretical calculation of density functional

Molecular structure was optimized using the BP86 functional method and the identity resolution method (RI). The excitation energy of the BP86 optimized structure was calculated using a time-dependent DFT (TD-DFT) method. The orbitals and excited state energies were calculated using the B3LYP functional method. Numerical integration was performed using the Def2-SVP basis set and using an m4 grid. The Turbomole package is used for all computations.

Photophysical measurement

Sample pretreatment: spin coating (Spin-coating)

The instrument comprises the following steps: spin150, SPS euro.

The sample was dissolved in a suitable solvent at a concentration of 10 mg/ml.

The procedure is as follows: 1)3 seconds, 400U/min; 2)20 seconds, 1000U/min and 1000 Upm/s; 3)10 seconds, 4000U/min, 1000 Upm/s. After coating, the film was dried at 70 ℃ for 1 minute.

Photoluminescence spectroscopy and TCSPC (time dependent Single photon counting)

The steady state emission spectra were recorded using a Horiba Scientific equipped with a 150W xenon arc lamp, excitation and emission monochromator, and a Hamamatsu R928 photomultiplier tube, with time-correlated single-photon counting option, model FluoroMax-4. Emission and excitation spectra were corrected using standard calibration fits.

The excited state lifetime was determined using the TCSPC method using the same test system (equipped with FM-2013 and Horiba Yvon TCSPC concentrator).

Excitation source:

NanoLED 370 (wavelength: 371nm, pulse duration: 1,1ns)

NanoLED 290 (wavelength: 294nm, pulse duration: <1ns)

SpectraLED 310 (wavelength: 314nm)

SpectraLED 355 (wavelength: 355 nm).

Data analysis (exponential fit) was performed using the software suite DataStation and DAS6 analysis software. Fitting was performed using the chi-squared-test.

Photoluminescence quantum yield measurement

For photoluminescence Quantum Yield (PLQY) measurements, the Absolute PL Quantum Yield Measurement C9920-03G system (Absolute PL Quantum Yield Measurement C9920-03G system, Hamamatsu Photonics) was used. The quantum yield and CIE coordinates were determined using software U6039-05 (version 3.6.0). The emission maximum is expressed in nm, the quantum yield Φ is expressed in% and the CIE coordinates are expressed as x, y values.

PLQY is determined using the following scheme:

1) quality assurance: anthracene (known concentration) in ethanol was used as reference

2) Excitation wavelength: determining the maximum absorption wavelength of an organic molecule and using that wavelength to excite the molecule

3) Measurement: the quantum yield of the solution or film sample was measured under nitrogen atmosphere. The yield was calculated using the following equation:

Wherein n is_photonRepresents the photon count and int.

Production and characterization of organic electroluminescent devices

OLED devices comprising the organic molecules of the present invention can be produced by vacuum deposition methods. If more than one compound is contained in a layer, the weight percentage of the one or more compounds is given in%. The percentage values of the total weight are 100%, so that if a certain compound content is not given, the percentage of this compound is equal to the difference between the given percentage of the other compound and 100%.

For incompletely optimized OLEDs, standard methods and the following measurements were used for characterization: measuring the electroluminescence spectrum, measuring the external quantum efficiency (expressed in% which depends on the intensity of light that can be detected with the photodiode, and measuring the current. The lifetime of the OLED device is inferred from the brightness change during operation at constant current density. The LT50 value corresponds to the time for the measured luminance to decrease to 50% of the initial luminance, similarly LT80 corresponds to the time for the measured luminance to decrease to 80% of the initial luminance, LT97 and so on.

Accelerated lifetime measurements (e.g., applying increased current density) were used. Illustratively, the LT80 value of 500cd/m2 is determined using the following equation:

Where L0 represents the initial brightness at the applied current density.

These values correspond to the average of several pixels (typically 2 to 8 pixels) and give the standard deviation between these pixels. The figure shows a data series for one OLED pixel.

Example D1 and comparative examples C1 and C2

TABLE 1 Properties of the materials

Measurement in 2-Me-THF solution

TABLE 2 setup of an exemplary organic electroluminescent device (OLED) (percentages refer to weight percent)

Device D1 produced an External Quantum Efficiency (EQE) of 16.8 + -0.3% at 1000cd/m 2. The LT80 value of 500cd/m2 was determined to be 23 hours from accelerated life measurements. The emission maximum was 469nm and the FWHM at 5W was 31 nm. The corresponding CIEy is 0.160 and CIEx is 0.127.

The comparative devices C1 and C2 included the same layer arrangement as device D1, except that the emissive layer contained only the emitter TADF1(C1) or DABNA2 (C2).

For device C1, the EQE at 1000cd/m2 decreased significantly to 7.7. + -. 0.1% and the lifetime was shorter (LT80 was 8h at 500cd/m 2). The emission maximum is 461nm, but since the FWHM is much greater than 58nm at 5V, the corresponding CIEy is 0.150, which is only slightly lower than that of D1. In addition, the corresponding CIEx was 0.145, which is inferior compared to D1.

For device C2, the EQE for 1000cd/m2 was 12.6. + -. 0.4% below D1 and the lifetime was significantly shorter (6 h for LT80 at 500cd/m 2). The emission maximum was 469nm, but since the FWHM was smaller at 5V to 28nm, the corresponding CIEy was 0.121 and CIEx was 0.124.

Claims (16)

1. An organic electroluminescent device comprising a light-emitting layer B comprising:

(i) host material H^NHaving a lowest excited singlet energy level S1^NA lowest excited triplet energy level T1^NOne energy is E^HOMO(H^N) Highest occupied molecular orbital HOMO (H)^N) And an energy of E^LUMO(H^N) Lowest unoccupied molecular orbital LUMO (H)^N)；

(ii) Host material H^PHaving a lowest excited singlet energy level S1^PA lowest excited triplet level T1P and an energy E^HOMO(H^P) Highest occupied molecular orbital HOMO (H)^P) And an energy of E^LUMO(H^P) Lowest Unoccupied Molecular Orbital (LUMO) (H)^P)；

(iii) Thermally Activated Delayed Fluorescence (TADF) Material E^BHaving a lowest excited singlet energy level S1^EA lowest excited triplet energy level T1^EOne energy is E^HOMO(E^E) Highest occupied molecular orbital HOMO (E)^E) And an energy of ELUMO (E)^E) Lowest unoccupied molecular orbital LUMO (E)^E) (ii) a And

(iv) full Width Half Maximum (FWHM) transmitter S^BHaving a lowest excited singlet energy level S1^SA lowest excited triplet energy level T1^SOne energy is E^HOMOHighest occupied score ofSub-orbital HOMO (E)^S) And an energy of ELUMO (E)^S) Lowest unoccupied molecular orbital LUMO (E)^S) In which S is^BEmission with an emission maximum λ maxP from 440nm to 475nm ^MMA(S) a light source for emitting light,

which satisfies the relationships represented by the following formulas (1) to (3) and the relationship represented by at least one of (4a) and (4 b):

S1^N>S1^E (1)

S1^P>S1^E (2)

E^LUMO(H^N)-E^HOMO(H^P)>S1^E (3)

E^LUMO(H^P)-E^LUMO(H^N)≥0.2eV (4a),

E^HOMO(H^P)-E^HOMO(H^N)≥0.2eV (4b),

and satisfies the relationships represented by the following formulas (5) to (8):

S1^N>S1^S (5)

S1^P>S1^S (6)

S1^E>S1^S (7)

S1^S<2.95eV (8)。

2. the organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is selected from the group consisting of an organic light emitting diode, a light emitting electrochemical cell and a light emitting transistor.

3. The organic electroluminescent device according to claim 1 or 2, wherein the TADF material E^BIs an organic TADF material.

4. The organic electroluminescent device according to claim 1 or 2, which satisfies formulae (4a) and (4 b).

5. The organic electroluminescent device according to claim 1 or 2, which has an emission maximum λ max (D) of 440 to 475 nm.

6. An organic electroluminescent device as claimed in claim 5 having an emission maximum λ max (D) of 450-470 nm.

7. The organic electroluminescent device according to claim 1 or 2, wherein the light-emitting layer B comprises:

(i) 10-84% by weight of a host compound H^P；

(ii) 10-84% by weight of a host compound H^N；

(iii) 5-50% by weight of TADF Material E^B(ii) a And

(iv) 1-10% by weight of a luminophore S^B。

8. The organic electroluminescent device according to claim 1 or 2, wherein the light-emitting layer B comprises:

(i) 10-30% by weight of a host compound H ^P；

(ii) 40-74% by weight of host compound H^N；

(iii) 15-30% by weight of TADF Material E^B(ii) a And

(iv) 1-5% by weight of a luminophore S^B。

9. The organic electroluminescent device according to claim 1 or 2, wherein the TADF material E^BExhibits an emission maximum λ maxPMMA (E) in the range from 440 to 470nm^B)。

10. The organic electroluminescent device according to claim 1 or 2, wherein the small FWHM emitter S^BIs an organic short range charge transfer (NRCT) emitter.

11. The organic electroluminescent device according to claim 1 or 2, wherein the small FWHM emitter S^BComprising or consisting of a structure of formula 1:

wherein the content of the first and second substances,

n is 0 or 1;

m＝1-n；

X¹is N or B;

X²is N or B;

X³is N or B;

w is selected from Si (R)³)₂,C(R³)₂And BR³；

R¹，R²And R³Each independently of the others selected from:

C₁-C₅alkyl which may optionally be substituted by one or more substituents R⁶Substitution;

C₆-C₆₀aryl, which may be optionally substituted by one or more substituents R⁶Substitution; and

C₃-C₅₇heteroaryl, which may optionally be substituted by one or more substituents R⁶Substitution;

R^I，R^II，R^III，R^IV，R^V，R^VI，R^VII，R^VIII，R^IX，R^Xand R^XIEach independently selected from the group consisting of:

hydrogen, deuterium, N (R)⁵)₂,OR₅,Si(R⁵)₃,B(OR⁵)₂,OSO₂R⁵,CF₃CN, halogen,

C₁-C₄₀alkyl which may optionally be substituted by one or more substituents R⁵Substituted and in which one or more non-adjacent CH₂Each of the radicals is optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se, C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵O, S or CONR⁵；

C₁-C₄₀Alkoxy, which may optionally be substituted by one or more substituents R ⁵Substituted and in which one or more non-adjacent CH₂Each of the radicalsFrom optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵O, S or CONR⁵；

C₁-C₄₀Alkylthio, which may optionally be substituted by one or more substituents R⁵Substituted and wherein one or more non-adjacent CH 2-groups are each optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵O, S or CONR⁵；

C₂-C₄₀Alkenyl which may optionally be substituted by one or more substituents R⁵Substituted and in which one or more non-adjacent CH₂Each of the radicals is optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵O, S or CONR⁵；

C₂-C₄₀Alkynyl which may be optionally substituted by one or more substituents R⁵Substituted and in which one or more non-adjacent CH₂Each of the radicals is optionally substituted by R⁵C＝CR⁵,C≡C,Si(R⁵)₂,Ge(R⁵)₂,Sn(R⁵)₂,C＝O,C＝S,C＝Se,C＝NR⁵,P(＝O)(R⁵),SO,SO₂,NR⁵O, S or CONR⁵；

C₆-C₆₀Aryl, which may be optionally substituted by one or more substituents R⁵Substitution; and

C₃-C₅₇heteroaryl, which may optionally be substituted by one or more substituents R⁵Substitution;

R⁵independently at each occurrence, selected from the group consisting of: hydrogen, deuterium, OPh, CF₃，CN，F，

C₁-C₅Alkyl, wherein optionally one or more hydrogen atoms are independently from each other deuterium, CN, CF₃Or F is substituted;

C₁-C₅alkoxy, in which optionally one or more hydrogen atoms are independently from each other deuterated, CN, CF₃Or F is substituted;

C₁-C₅thio group, in which optionally one or more hydrogen atoms are deuterium, CN, CF independently of one another₃Or F is substituted;

C₂-C₅alkenyl, wherein optionally one or more hydrogen atoms are independently from each other deuterium, CN, CF ₃Or F is substituted;

C₂-C₅alkynyl, wherein optionally one or more hydrogen atoms are independently from each other deuterium, CN, CF₃Or F is substituted;

C₆-C₁₈aryl optionally substituted by one or more C₁-C₅Alkyl substituent group substitution;

C₃-C₁₇heteroaryl optionally substituted by one or more C₁-C₅Alkyl substituent group substitution;

N(C₆-C₁₈aryl radical)₂，

N(C₃-C₁₇Heteroaryl group)₂(ii) a And

N(C₃-C₁₇heteroaryl) (C₆-C₁₈Aryl groups);

R⁶independently at each occurrence, selected from the group consisting of: hydrogen, deuterium, OPh, CF₃，CN，F，

C₁-C₅Alkyl, wherein optionally one or more hydrogen atoms are independently from each other deuterium, CN, CF₃Or F is substituted;

C₁-C₅alkoxy, in which optionally one or more hydrogen atoms are independently from each other deuterated, CN, CF₃Or F is substituted;

C₁-C₅thio group, in which optionally one or more hydrogen atoms are deuterium, CN, CF independently of one another₃Or F is substituted;

C₂-C₅alkenyl, wherein optionally one or more hydrogen atoms are independently from each other deuterium, CN, CF₃Or F is substituted;

C₂-C₅alkynyl, wherein optionally one or more hydrogen atoms are independently from each other deuterium, CN, CF₃Or F is substituted;

C₆-C₁₈aryl optionally substituted by one or more C₁-C₅Alkyl substituent group substitution;

C₃-C₁₇heteroaryl optionally substituted by one or more C₁-C₅Alkyl substituent group substitution;

N(C₆-C₁₈aryl radical)₂，

N(C₃-C₁₇Heteroaryl group)₂(ii) a And

N(C₃-C₁₇heteroaryl) (C₆-C₁₈Aryl groups);

wherein two or more are selected from R ^I，R^II，R^III，R^IV，R^V，R^VI，R^VII，R^VIII，R^IX，R^XAnd R^XIAre adjacent to one another and form a monocyclic or polycyclic, aliphatic, aromatic and/or benzo-fused ring system, and

wherein X¹，X²And X³At least one of B, X¹，X²And X³Is N.

12. The organic electroluminescent device according to claim 11, wherein X¹And X³Each is N and X²Is B.

13. The organic electroluminescent device according to claim 11, wherein X¹And X³Each is B and X²Is N.

14. The organic electroluminescent device according to claim 11, wherein n-0.

15. The organic electroluminescent device according to claim 11 or 14, wherein

R^I，R^II，R^III，R^IV，R^V，R^VI，R^VII，R^VIII，R^IX，R^XAnd R^XIEach independently selected from the group consisting of:

hydrogen, deuterium, halogen, Me, iPr, tBu, CN, CF₃，

Ph, optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF₃And a substituent for Ph,

pyridyl optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF₃And a substituent for Ph,

pyrimidinyl, optionally substituted by one or more radicals independently of one another selected from Me, iPr, tBu, CN, CF₃And a substituent for Ph,

carbazolyl, optionally substituted by one or more groups independently selected from Me, iPr, tBu, CN, CF₃And a substituent for Ph,

Triazinyl, optionally substituted by one or more radicals independently selected from Me, iPr, tBu, CN, CF₃And Ph, and

N(Ph)₂(ii) a And

R¹and R²Each independently selected from the group

C¹-C⁵Alkyl optionally substituted by one or more substituents R⁶Substitution;

C⁶-C³⁰aryl, optionally substituted by one or more substituents R⁶Substitution; and

C³-C³⁰heteroaryl, optionally substituted by one or more substituents R⁶And (4) substitution.

16. A method for generating blue light having a wavelength of 440 to 475nm, comprising the steps of:

(i) providing an organic electroluminescent device according to any one of claims 1 or 2; and

(ii) applying a current to the organic electroluminescent device.